1983 research outputs found
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Reimagining Rights and Responsibilities in the United States: Freedom of Speech and Media
No full textThis paper is part of the Reimagining Rights & Responsibilities in the United States Project from the Carr Center for Human Rights Policy.The First Amendment guarantees some of the most fundamental rights provided to Americans under the Constitution. The right to free expression is a foundational tenet of American values. In fact, it was the First Amendment rights to freedom of speech and the press that provided much of the basis for the revolution that led to America’s founding. The First Amendment provides broad protection from government censure of speech, although limitations on some forms of published or broadcast speech, such as obscenity and hate speech, have been allowed.
As the traditional public square governed and protected by federal regulation moves online to spaces governed by private corporations, the rules for how speech is both expressed and censored are also changing. How should legal protections for speech adapt to these new tech-powered, private forums? This chapter will explore the current landscape of free speech and the associated information landscape as well as the threats that they face.Version of Recor
Foundational Competencies in Educational Measurement: A Rejoinder
No full textWhat are foundational competencies in educational measurement? We published a framework for these foundational competencies in this journal (Ackerman et al.) and were grateful to receive eight commentaries raising a number of important questions about the framework and its implications. We identified five cross‐cutting recommendations among the eight commentaries relating to (1) our process and purpose, (2) Artificial Intelligence, (3) ethical competencies, (4) qualitative, critical, and culturally responsive commentaries, and (5) intersecting professions in, for example, classroom assessment and content development. In this rejoinder, we respond to these five recommendations and to each of the eight commentaries in turn. We hope that discussion and consensus about foundational competencies in educational measurement continue to advance in our journals and our field.Accepted Manuscrip
Study of the Extracellular Self-DNA Inhibitory Effect in Model Fish Danio rerio (Zebrafish)
No full textThis study investigates the effects of extracellular self-DNA (esDNA) on the survival and reproductive activity of Danio rerio (zebrafish), a model organism extensively used due to its genetic similarity to humans and quick life cycle. Specifically, the impact of an esDNA infused spirulina diet on zebrafish lifespan, egg deposition, larval development and reproductive cell count is assessed. Zebrafish were divided into two treatment groups with varying concentrations of esDNA infused spirulina (5% and 25%) and compared against several control groups. Survival rates were monitored over a 12-month period, and reproductive metrics were assessed during a period of 6-7 months through microscopic counting of eggs and larvae, and histological analysis of tissue to count reproductive cells. The primary outcomes reveal that although esDNA exposure did not have a statistically significant effect on egg deposition and larvae development, differences in mean reproduction and especially in mean larvae development are observed. This study utilizes Kaplan-Meier survival analysis and one-factor ANOVA to evaluate differences across groups. Findings from this research contribute to understanding the role of esDNA in aquatic environments, which previous studies have not addressed, In addition, this study helps understand whether administering esDNA via a diet may have the expected inhibitory effect as observed in other model organisms. Several avenues for further research are suggested, centered around understanding the potential of species-specific growth control; the key use case of esDNA in a wide variety of biological settings
Entrepreneurship, Social Networks, and Economic Opportunity
No full textThis collection of essays explores the importance of interpersonal relationships for economic phenomena. Chapter 1 analyzes the role of social networks measured on Facebook in promoting the formation of new businesses in the United States. I find that connections to existing entrepreneurs encourages individuals to start firms. The importance of connections to entrepreneurs differs dramatically by demographic group and location, suggesting that existing policies could be targeted in ways that increase their effectiveness. Chapter 2 demonstrates theoretically how relationships among entrepreneurs might contribute to long-run city population growth. The model predicts that city population growth increases after a negative shock to physical capital, consistent with the existing literature, but growth decreases after a negative shock to human capital. I test for the effects of a negative shock to human capital using differences in mortality from the 1918 Influenza across U.S. cities, and find that the long-run growth effects from the pandemic match the predictions of the model. Chapter 3 returns to social network data from Facebook in order to construct new measures of social capital based on literatures across the social sciences. I demonstrate the importance of distinguishing these forms of social capital by analyzing their associations with economic mobility across areas in the U.S. I find that differences in connections between high-SES and low-SES individuals is among the strongest predictors of upward economic mobility found to date
Maya Vase Rollout Photography’s Past, Present, and Potential in a Cross-Discipline Digital Future: A Proof-of-Concept Study
No full textVase rollout photography has emerged as an invaluable tool for artifact study and documentation, offering scholars a comprehensive, 360-degree perspective of an object’s painted imagery and hieroglyphic texts. Over the past five decades, the creation of vase rollout images has predominantly relied on film and a specialized workstation pioneered by photographer and Mayanist Justin Kerr. The transition to modern digital methods has been gradual, characterized by limited and predominantly manual efforts. This thesis investigates the historical trajectory, current status, and potential future of digital vase rollout photography within the realm of archaeological documentation and study.
This thesis hypothesizes that recent advancements in digital photography coupled with image-processing and image understanding techniques from the field of computer vision can be integrated to automate the process of creating rollouts. The research and results presented here demonstrate that automated digital rollout images can be created with high quality and fidelity, suitable for use as a new standard form of artifact archival documentation. Through a novel combination of commercial off-the-shelf hardware and purpose built software, this thesis introduces a proof-of-concept experiment showcasing the attainability of excellent quality software-generated digital rollouts in a platform that requires minimal investment. The digital rollout archive made possible by this method is envisioned as a potentially valuable resource, supplying the necessary digital inputs for the creation of yet-to-be-developed artifact analysis tools in the future
A Cyanobacterial Carbon Removal System in North Africa
No full textThis dissertation examines the construction of a carbon dioxide removal system using the growth, lysis, harvest, drying, salting, and burial of cyanobacteria. It employs methodology from biology, environmental science, engineering, economics and social sciences in order to demonstrate the ability of such an algal carbon dioxide removal project to be operated at a cost of less than $100 per ton CO2 and the gigaton scale, while respecting ethical, political, and environmental concerns
Slaves without Masters: The Feudal Imagination and the Critique of Impersonal Domination
No full textA signal ambition of the liberal political project is the abolition of the arbitrary, capricious rule of man, and the establishment in its place of the impartial, rational rule of law. This dissertation is a study of a complaint that emerges in response to the triumph of this liberal vision of politics. Constitutional government and the market economy do away with the juridical inequality and personal hierarchy associated with medieval feudalism. Instead of delivering emancipation, however, this triumph of liberalism is accused of establishing new forms of depersonalized domination. No longer at the mercy of arbitrary lords or tyrants, modern subjects are said to be oppressed or constrained by systems and structures beyond the will of any recognizable rulers or elites. Liberal subjects, the argument goes, have become slaves without masters.
To better understand the origins and nature of this critique, my dissertation turns to a surprising historical tradition: the reinterpretation of medieval feudalism in the hands of nineteenth-century critics of liberal political economy. Feudalism constituted a perfect foil for the new constitutional state and market system. Where liberal societies separate the private from the public, feudalism entailed a unity of political and economic authority. The Middle Ages—long taken by republican and liberal thinkers to be synonymous with the tyrannical rule of man—came to serve as a means of diagnosing the anarchic and impersonal nature of liberal societies. I document how widespread this reinterpretation of feudalism was in the nineteenth century among conservative reactionaries, liberal romantics, and radical socialists. For those attempting to diagnose the new servitude, appeals to feudalism served as a common vessel for wildly divergent moral, economic, and political programs.
Chapter one of this dissertation provides an overview of the many uses to which feudal nostalgia was put in the decades following the French Revolution. I trace how English and continental romantics, conservatives, and radicals invoked idealized accounts of feudalism to critique the cold, atomistic, and spiritless nature of modern politics. Chapter two takes up Thomas Carlyle’s critique of the anarchic “age of mechanism” and his turn to the “most perfect feudal ages” as an inspiration for a new form of mastery. Chapter three turns to the young Marx and his enigmatic description of medieval feudalism as the “democracy of unfreedom.” Attending to Marx’s account of the integrated spirit of the Middle Ages helps to clarify what he terms “human emancipation” and “true democracy.” Chapter four takes up Alexis de Tocqueville’s contrast between the personal, master-servant relations characteristic of aristocratic feudalism and the impersonal, tutelary servitude he fears will arise in democracies. Chapter five offers a critical, conceptual study of the three divergent programs that flow from Carlyle, Marx, and Tocqueville’s superficially similar interpretations of medieval feudalism. Chapter six connects this intellectual history with a debate in contemporary political theory concerning the nature of “depoliticization.” By critically evaluating rival understandings of that term, I argue that the most philosophically potent meaning of depoliticization is an extension of the slaves-without-masters critique. A liberal demand to minimize the role of arbitrary will and rule and to elevate institutionalized forms of impartial reason leads to an objectionable offloading of responsibility to the market economy and to non-political sites of governance like the bureaucracy and judiciary
Urban Climate Health Risks and Resilience
No full textThe effects of climate change health impacts on urban health care systems and vulnerable populations are a researched topic with foundations on urban risk management, urban health methodologies, and sustainable urbanization. As climate change is a dynamic and transformative global issue the gap between adaptation and mitigation efforts and urban planning relies, among other things, in the limitations of previous studies of risk management structures tailored to the existing strategy to calculate the uncertainties and predict their influence on urban systems and subsystems. Moreover, Although, there is vast documentation on health and urbanization challenges facing climate change impacts, little is known about climate health risks affecting the megacities’ urban poor and the available methodologies to cope with climate health risks in urban environments. Climate and health is a well-researched issue, it is also complex as the methodologies and strategic approach to minimize health risks of climate change is intrinsically contingent to risk methodologies and policy-making processes that are efficient with support of knowledge-based information. This paper emphasis the need for strategic applications and frameworks on urban health risk management methods that serves to identify potential opportunities, and then manage and take action to prevent adverse health effects. It also emphasizes the probability of events and their consequences, which are measurable both qualitatively and quantitatively.Author's Origina
Spin Waves as New Probes for Graphene Quantum Hall Systems
No full textThis thesis introduces two pioneering experimental techniques—magnon scanning gate microscopy (MSGM) and magnon transmission spectroscopy (MTS)—which utilize magnons in monolayer graphene quantum Hall ferromagnets (MLG QHFM) as probes to study spin orders in graphene-based systems. These methods leverage the principles of electrical generation and detection of spin waves (magnons) in graphene quantum Hall systems using two edge states with opposite spins.
The first experiment, MSGM, provides spatially resolved insights into magnon transport within MLG QHFM. By employing a metallic scanning tip, we create a movable, localized scattering target that influences magnon transport in the system. Observations of tip-induced changes in two-terminal conductance and nonlocal voltage enable us to visualize the localized nature of magnon generation and absorption processes, as well as magnon propagation within the quantum Hall ferromagnet. Furthermore, this experiment uniquely highlights the importance of localized states in inducing spin flips across two chiral edge states, a process previously invisible to transport measurements alone.
The second experiment, magnon transmission spectroscopy, leverages magnons from MLG QHFM to study spin order in a non-MLG system. Specifically, we launch magnons from MLG QHFM towards bilayer graphene (BLG) QHFM to probe the spin order of symmetry-broken states in BLG Landau levels. The sharp onset of nonlocal signals at Zeeman energy in BLG contacts indicates effective magnon transmission between the two systems, demonstrating the utility of magnons in revealing spin order within graphene multilayer devices. This method opens new avenues for assessing spin order in various exotic emergent phases in graphene heterostructures and other flat-band systems.
Together, MSGM and MTS enhance our capability to probe and understand spin orders and collective excitations in graphene quantum Hall systems. The principles underlying these techniques are not limited to graphene systems but can be generalized to other Chern band systems, providing an exciting pathway for future exploration of quantum phases of matter
A Machine Learning-Driven Methodology for the Design of Exchange-Correlation Functionals
No full textComputational chemistry and materials science aim to explain and predict the behavior of chemical systems using computational models. To achieve this goal, we require a method that accurately describes the ground state electronic structure of chemical systems. Due to its combination of computational efficiency and accuracy, density functional theory (DFT) is the most popular tool for these calculations. However, while DFT is exact in principle, the formalism contains a term called the exchange-correlation (XC) functional, which provides the energy difference between the exact interacting-electron system and a model non-interacting system. This XC functional is unknown and therefore must be approximated in practice, and this approximation is the key limiting factor in the accuracy of DFT.
Recently, machine learning (ML) has gained attention as a means to develop more accurate XC functionals. While significant progress has been made in this direction, it has proven difficult to overcome the persistent trade-offs between accuracy, computational efficiency, numerical stability, and chemical transferability. To address this problem, we developed a framework called CIDER for learning XC functionals that are accurate, transferable, and efficient. CIDER consists of two key components. First, we use a Bayesian machine learning model called Gaussian process regression to learn functional forms that can be carefully tuned to balance accuracy and smoothness, an important trade-off in functional design. Second, we design nonlocal features of the density that enable the model to obey exact physical constraints on the exchange functional, and we implement computationally efficient algorithms to evaluate these features within different types of DFT software. The combination of fast, nonlocal input features with a flexible and tunable ML model enables the accurate description of molecular and solid-state systems within a single model. We also extend the CIDER framework to explicitly fit band gaps and other electronic properties, thereby addressing the infamous band gap problem of DFT within a machine learning framework.
In this dissertation, I will first provide introductions to DFT and Gaussian process regression, and then I will provide an overview of existing research on ML XC functionals and outstanding challenges in the field. After that, I will describe the CIDER framework in detail, including the theoretical justification for the structure of the XC functional, the computationally efficient implementation of the models, and the application of CIDER functionals to physically complex problems requiring large-scale materials simulations, such as point defects in semiconductors and polarons in ionic crystals