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EXAMINATION OF THE ROLE OF THE MICROBIOME DURING MICROBIAL INVASION OF THE FRUIT FLY DROSOPHILA MELANOGASTER
Get PDFAnimal life is closely associated with microorganisms. Microbial invasion, the entry and colonization of foreign microbes in new niches, is dependent on the combined actions of the host and the microbe. Invasion by probiotic microorganisms is notable for the beneficial effects imparted on the host. However, other invasive microbes may have no effect or deleterious effects on the host, resulting in disease. Direct studies of microbial invasion in the context of the human microbiome are often complicated by the immense species diversity and varying oxygen requirements of the gut-associated community. Therefore, model hosts are essential to building upon our understanding of how microbiomes impact animal physiology. In this dissertation, I use the common fruit fly Drosophila melanogaster and its associated gut microbiome to elucidate host and microbial factors that govern microbial invasion. In Chapter 2, I examine microbe-microbe interactions between the D. melanogaster gut microbiome and invasive microbes, and I find that the microbiome protects the host against invasion in a pH-dependent manner. In Chapter 3, I explore the microbial fitness determinants that underlie the ability of invasive microbes to colonize the D. melanogaster intestine and report that invasion is tightly linked to how the invading organism responds to host-induced stress. Chapter 4 provides insight into how the D. melanogaster diet affects the microbial composition and biochemical environment to which flies are exposed. In total, my dissertation builds upon our understanding of the host, microbial, and biochemical levers that control the process of microbial invasion. The findings I present herein answer important questions of clinical and industrial significance
THREE ESSAYS IN LABOR AND EDUCATION ECONOMICS
Get PDFThis dissertation investigates various topics in labor and education economics. The first chapter conducts a cost-benefit analysis of a state's tuition subsidy policy to understand whether an increase in tuition subsidy is beneficial for state governments. I estimate a structural model of a college choice and student’s migration after graduation using the restricted version of the Education Longitudinal Study of 2002 data. Then, I perform a counterfactual analysis of different tuition subsidy policies to predict the change in state income tax revenue net of different tuition subsidy costs, taking into account changes in students’ college choices and migration decisions after graduation. My estimation results show that the expansion of a tuition subsidy policy is effective in maintaining a sizable working population and subsidizing community college students is the least costly option. But, the additional tax revenue cannot cover the total costs in the long run if the state income tax rate is fixed at the current level. However, the long-run effect of the expansion of a tuition subsidy policy results in a positive economic benefit as it boosts the total earnings more than the total costs. The results show that a state with a high amenity value and high expected wages should subsidize in-state students of elite public colleges while a state with a lower amenity value and low expected wages is better off when it subsidizes in-state students of non-elite public colleges. The second chapter tests how much the results in the previous study, Winters (2020), are robust to the violation of the exclusion restriction using the proposed method by Conley et al. (2012). Using the method of Conley et al. (2012), I show how the results in Winters (2020) would change when the exclusion restriction is violated to a different degree. I find that the main empirical result of the previous research still holds for most cases, that is, the in-state college enrollment rate has a positive effect on later life in-state residence even if the exclusion restriction is not satisfied. However, the magnitude of the causal effect may be substantially different when the exclusion restriction is violated to a higher degree for some prior beliefs on the violation. I also find that some of the other instruments used in Winters (2020) are actually stronger instruments than the in-state tuition rate in the context of Conley et al. (2012) for certain cases. I also explore potential alternative instruments that are not used by Winters (2020). Specifically, personal income per capita at age 18 can be used as an alternative instrument when the exclusion restriction is relaxed under certain conditions. The third chapter examines the effect of the military service experience of South Korean men on the gender role perception in the labor market and home production by utilizing the data collected from new relevant survey questions of the Korea Labor and Income Panel Study (KLIPS) in 2021. The regression results show that military service experience has a small but statistically significant effect on forming conservative gender role perceptions for men even when other key variables such as birth cohort effects and years of schooling are controlled. I used enlistment demands for each birth cohort and an indicator of the high level of parental positions at work as instruments. The IV estimates that modify for omitted variables bias of military service experience show an even larger negative effect of military service experience on the gender role perception in the labor market and home production for men. When the gender role perception is decomposed into family and workplace perceptions, military experience has a significant effect on forming conservative gender role perceptions in family affairs for men while it does not have a significant effect on the gender role perception in workplace affairs
Declarative Programming via Term Rewriting
No full textI present a new approach to implementing weighted logic programming languages. I first present a bag-relational algebra that is expressive enough to capture the desired denotational semantics, directly representing the recursive conjunctions, disjunctions, and aggregations that are specified by a source program. For the operational semantics, I develop a term-rewriting system that executes a program by simplifying its corresponding algebraic expression.
I have used this approach to create the first complete implementation of the Dyna programming language. A Dyna program consists of rules that define a potentially infinite and cyclic computation graph, which is queried to answer data-dependent questions. Dyna is a unified declarative framework for machine learning and artificial intelligence researchers that supports dynamic programming, constraint logic programming, reactive programming, and object-oriented programming. I have further modernized Dyna to support functional programming with lambda closures and embedded domain-specific languages.
The implementation includes a front-end that translates Dyna programs to bag-relational expressions, a Python API, hundreds of term rewriting rules, and a procedural engine for determining which rewrite rules to apply. The rewrite rules generalize techniques used in constraint logic programming. In practice, our system is usually able to provide simple answers to queries.
Mixing disparate programming paradigms is not without challenges. We had to rethink the classical techniques used to implement logic programming languages. This includes the development of a novel approach for memoization (dynamic programming) that supports partial memoization of fully or partially simplified algebraic expressions, which may contain delayed, unevaluated constraints. Furthermore, real-world Dyna programs require fast and efficient execution. For this reason, I present a novel approach to just-in-time (JIT) compile sequences of term rewrites using a custom tracing JIT
“GO” A LOOK AT OUR WORLD GOING THROUGH, UNDER, AND ABOVE IT
No full textTo “go” seems so simple. Up we get, and off we go. Yet this simple act can be profound. By going, we learn about our world. We go to new places and peer into corners in new ways, looking for understanding and meaning. We go to extreme ends of the earth and study animals capable of going further or faster than we can ever dream of with our limited human bodies. And yet, those bodies can go when pushed or driven. “Go” is a collection of essays and articles in which going plays a key role in the way we understand life on Earth
The Plasmodium circumsporozoite protein
Get PDFThe circumsporozoite protein (CSP) is one of the most studied proteins of the malaria parasite. It is the target of the only licensed malaria vaccines and is essential for sporozoite formation and infectivity. Yet, the mechanisms by which CSP functions and its interactions with other proteins are only beginning to be understood. Here we review the current state of knowledge of CSP structure and function, as sporozoites develop in the mosquito and establish infection in the mammalian host, and outline outstanding questions that need to be addressed
Oral History Interview with Miles, Steven H.
No full textThis interview with Dr. Steven Miles, MD is part of Moral Histories: Voices and Stories from the Founding Figures of Bioethics, an oral history project of the Johns Hopkins Berman Institute of Bioethics. Steven Miles is Professor Emeritus of Medicine and Bioethics at the University of Minnesota. Dr. Miles discusses his upbringing in Minnesota and his time at St. Olaf College, where he developed a passion for social justice, feminism, and student activism. Miles describes his medical school experiences at the University of Minnesota and residency at Hennepin County Medical Center where he began his early work on DNR orders, palliative care, and a geriatric medicine specialization.
He discusses his active participation as an expert witness in various court cases and public policy issues that highlighted the importance of applying bioethical principles. He highlighted the Wanglie case, where he testified against providing non-beneficial therapy to a terminally ill patient, leading to a court ruling that there was no obligation to do so. Other cases discussed include the excessive use of restraints in nursing homes, execution methods as capital punishment, force-feeding prisoners in the War on Terror, and the prescription of cyanide to Special Forces. Miles criticizes the medical ethics community for focusing on expensive, highly specialized medical developments while neglecting more common problems, such as unsafe conditions in nursing homes, “dumping” patients (EMTALA statute), and medical inequality.
Dr. Miles shares his research on the Abu Ghraib scandal during the Iraq War, which involved analyzing nearly 100,000 government documents to trace how medical staff participated in torture and interrogations. Miles' work led to the publication of Oath Betrayed, detailing the U.S. torture program, and The Torture Doctors, highlighting international medical complicity in torture. He emphasized the need for accountability and the failure of the World Medical Association to address these issues. Miles also shared his experiences in Sudan and Cuba advocating for ethical practices in war and healthcare
China Studies Review, Issue no. 10 (2024)
No full textSince the previous edition of the SAIS China Studies Review was published, the world has witnessed China’s difficult recovery from the Covid-19 pandemic. Youth unemployment remains a thorn in China’s economy, and international concerns around China’s industrial overcapacity are pressing, rais ing questions about the country's 5% GDP growth target stipulated in its 2024 “Two Sessions.” China has also been carefully navigating itself through the increasingly unstable international environment. Despite its continuous behind-the-scenes support for Russia in the Ukraine War, China has taken a neutral stance in the “Palestinian-Israel conflict,” a phrase that its Ministry of Foreign Affairs uses. China’s reaction to Taiwan's election also has been characteristically strong, adding more tensions to the cross-Strait relations. Fortunately, U.S-China relations have moved beyond its lowest point since the Biden-Xi summit in San Francisco last November. The two countries have resumed collaborations on issues including fentanyl, climate change, and people-to-people exchange, yet the upcoming U.S. election has cast uncertainty over whether this nascent progress in the bilateral relationship can be sustained. With the urgent need to understand China’s policies and its evolving role in the world, the Review begins with Aaron Dane’s insightful analysis of China's transition in energy security. The Review then presents Jacob Wright’s careful investigation into the ideological origin of and the economic rationale behind the country’s “Outlook on Scientific Development,” with a novel case study of China’s national park system. Next, Myong-jun Kim delves into Taiwan’s presence in Washington, D.C. In assessing China’s rising influence as an
international actor, Qingyu Tao examines the consequences of China's cross-border engagements on local security. The tenth volume concludes with Anqing Zhao’s analysis of China’s rising role in the global lithium mining industry and its growing involvement in South America
PASS_E2E_TEST_SUBMISSION_JOURNAL:Tue May 07 2024 21:34:56 GMT+0000 (Coordinated Universal Time)
No full textCHARACTERIZING THE DOLLAR STORE FOOD ENVIRONMENT TO INFORM POLICIES TO IMPROVE HEALTHY FOOD ACCESS IN BALTIMORE
Get PDFBackground
There over 35,000 dollar stores nationwide. They tend to be prevalent in some of the most vulnerable communities, and have recently garnered attention from the press, community members, and policy makers across the country. Common concerns raised about dollar stores include their density in certain areas, lack of healthy food options, lack of cleanliness, and poor working conditions and treatment of staff.
Objective
Despite recent policy action against dollar stores, the dollar store evidence base is extremely limited. The objectives of this dissertation were to: 1) characterize the Baltimore City dollar store retail environment; 2) understand how community members view and utilize them; and 3) explore community member and policy maker support for dollar store policies.
Methods
A sequential mixed-methods approach was used and included three phases: 1) in-depth interviews with community members, local retailers, dollar store staff, and policy makers; 2) structured dollar store observations and an online survey of Baltimore City residents; and 3) two workshops: one with community members and one with policy makers.
Results
Participants acknowledged that dollar stores meet certain needs in their community by offering necessities at affordable prices, in convenient locations. However, they do not otherwise contribute positively to the community, and participants want dollar stores to invest in the neighborhoods they serve. Only four dollar stores offered fresh produce, while many stocked canned and frozen produce, milk, and eggs. Ultra-processed foods were highly prevalent across all stores. There was strong support across data sources for policies that would improve existing dollar stores, as opposed to shutting them down or banning them entirely.
Conclusions
Baltimore City community members want better, cleaner dollar stores that contribute to the community and offer healthy options. Future policies should consider strategies for improving existing stores to meet community needs
Automatic enrollment in advanced courses: A bipartisan approach to excellence and equity in K-12 schools
Get PDFAutomatic enrollment is a straightforward education reform that facilitates both educational excellence and equity in K-12 schools. By automatically placing highly qualified students in advanced coursework, this low-cost, bi-partisan strategy creates opportunities for high achievement for all students, with low-income, rural and small town, and underrepresented minority students especially appearing to benefit