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A spatiotemporal analysis of collective human mobility patterns and crime variations in Baltimore City
No full textResearchers have examined the patterns of peoples’ spatiotemporal movements to understand various aspects of our society, including urban crime risks. While prior research has extensively explored individual mobility, collective mobility patterns have received relatively little attention. The growing availability of mobile device location data offers new opportunities to analyze those collective patterns, which used to be challenging to capture. Traditionally, residential mobility and inward flow have been used to study collective mobility, but other measures—such as outward flow—have often been overlooked. Beyond the primary relationship, the spatial distribution of local security measures, such as the intensity of police patrols, may further influence this connection. Temporal variations in the mobility-crime relationship may also arise due to factors like seasonal temperature changes, shifting activity preferences, uneven distribution of holidays, and differences in traveler composition across days of the week.
This study explores the relationship between collective human mobility patterns and crime victimization in Baltimore City. It also examines how mobility-crime connections vary across different neighborhoods with intense police activities and during different periods. Using a comprehensive dataset that integrates mobile device location data, official crime reports, and community-level information, the study examines three crime types: homicide, robbery, and burglary. The primary mobility indicators include residential mobility, inward population flow, and outward population flow. Poisson regression with Moran Eigenvector Spatial Filtering (MESF), controlling for ambient population as an exposure variable, is used for the analysis.
Key findings include: (1) higher volumes of inward and outward population flows are consistently associated with lower robbery and burglary rates, while residential mobility is positively associated with burglary rates; (2) neighborhoods with more intense police activity exhibit a stronger positive link between mobility and crime; and (3) both seasonal and intra-week (weekday vs. weekend) variations exist in the mobility-crime relationship, though clear seasonal patterns are lacking. Weekday-weekend differences are particularly notable for inward population flow. Those results highlight the importance of collective mobility in shaping local crime risks and call for deeper investigation into the nuanced dynamics between collective mobility and urban safety
HYBRID QUANTUM NEURAL NETWORK AND SHAPELY ADDITIVE EXPLANATIONS IN RAIL TRACK GEOMETRY DEFECT PREDICTION
No full textThis study applies quantum machine learning, which brings together quantum computing and machine learning, for predictive maintenance in the railroad industry. Rail companies invest substantially in their networks to achieve their objective of a safe and efficient railroad. However, derailments caused by track geometry defects pose significant risks to this objective. Issues such as profile deviations and alignment irregularities often lead to train derailments, which can disrupt operations and increase repair costs. Therefore, there is a need for predictive strategies. To address this challenge, this research develops a quantum neural network (QNN) to predict track profile and alignment defects based on subsurface conditions, utilizing data obtained from Ground-penetrating Radar (GPR), which includes the ballast fouling index, ballast thickness index, layer roughness index, and moisture likelihood index. The developed QNN consists of a ZZ feature map layer and an EfficientSU2 ansatz layer, trained using the COBYLA and LBFGS optimizers. Additionally, a classical neural network (CNN) was developed to establish a baseline for comparison. Furthermore, Shapley Additive Explanations (SHAP) were employed to analyze the QNN’s decision-making process, ensuring interpretability for practical applications. The study’s findings indicate that the QNN, trained with the COBYLA optimizer, outperformed the CNN in predicting alignment defects, while the CNN performed better for the left profile. Both models exhibited similar results for the right profile. SHAP analysis revealed that the layer roughness index and ballast fouling index were the most influential factors in predicting defects in track geometry, followed by the ballast thickness index, with the moisture likelihood index being less significant. These results align with engineering principles, confirming the model’s suitable performance. This work demonstrates that QNNs can improve predictive maintenance, with SHAP providing a clear understanding of the model’s predictions for industry use
EFFECT OF MULTIAXIAL VIBRATION ON FATIGUE DURABILITY OF ELECTRONIC ASSEMBLIES POPULATED WITH SHORT AND LIGHT COMPONENTS
No full textMultiaxial vibration can lead to nonlinear cross-axis interactions, which can significantly affect the fatigue durability of electronic printed circuit assemblies. Depending on the frequency and phase relationship between the in-plane and out-of-plane excitations, there can be significant reduction or increase in fatigue durability. Previous studies used experiments and nonlinear dynamic finite element simulations to highlight this nonlinear impact in tall, heavy electronic components such as insertion-mount inductors, wherein the most severe multiaxial interactions resulted in damage that was twice the linear summation of damage caused by corresponding levels of sequential uniaxial vibrations. The root-cause of the multiaxial effects was determined to be kinematic nonlinear interactions between large deformations in orthogonal axes. This dissertation builds on this work by conducting two related studies described below.The first study in this dissertation builds on a prior parametric study, to confirm the findings stated above for tall, heavy components. Simple beam specimens are designed to represent the kinematic features of tall heavy components with flexible leads mounted on flexible printed circuit boards (PCBs). Single and double beam tests were conducted with varying height and mass to parametrically examine the influence of geometry on nonlinear behavior. The purpose of the single beam configuration is to identify the nonlinear role of the flexible leads and the purpose of the double-beam is to investigate the nonlinear interactions between the flexible leads and the flexible PCBs. The tip response is recorded for various uniaxial and multiaxial excitation profiles to establish the nonlinear interactions. Dynamic, nonlinear finite element analysis (FEA) is also performed, to validate the experimental results, confirming that kinematic nonlinearity plays a crucial role in the observed multiaxial nonlinear effects.
The second part of this study extends the multiaxial vibration durability investigation to examine the feasibility of nonlinear multiaxial interactions in short, light components, such as surface-mount gull-wing quad-flat packages (QFPs), since the deformation magnitudes (and hence the kinematic nonlinear interactions) are expected to be significantly smaller in such cases. Two different types of QFP components are used in printed circuit assemblies (PCAs): QFP100 and a low-profile component LQFP100. Multiaxial random vibration experiments conducted in this study demonstrate that even these light, low-profile components exhibit strong multiaxial nonlinear effects. In fact, the lower-profile LQFP100 demonstrates even higher multiaxial interaction than the regular profile QFP100. These unexpected findings suggest the presence of an additional source of nonlinearity for cross-axis interaction: possibly cross-axis interaction due to material nonlinearity. The failure mode is revealed to be predominantly lead fatigue in both QFP100 and LQFP100 assemblies.
To further explore these nonlinear effects, multi-scale nonlinear dynamic finite element models of QFP100 and LQFP100 assemblies are developed and vibration response is simulated for both uniaxial and multiaxial vibration. In the interest of model simplification, the finite element simulations are limited to harmonic analysis, since the underlying physics of the nonlinearity is expected to be the same for both random and harmonic vibration. These models are used to analyze strain distributions in the leads and to conduct fatigue analysis, providing deeper insights into the material and geometric interactions that lead to multiaxial nonlinear effects. The simulations confirm the trends of the experimental results, illustrating that multiaxial vibration can generate complex nonlinear interactions even in short, light electronic components under multiaxial vibration.
This dissertation highlights the importance of considering multiaxial nonlinear effects when designing and qualifying electronic components for dynamic environments, regardless of height or mass. The findings emphasize the need for comprehensive testing and modeling approaches to accurately assess the reliability and durability of electronic assemblies that are subjected to multiaxial vibrations, for both heavy, tall components as well as light, short components
MECHANO-METABOLIC SIGNATURES OF METASTATIC DISEASE
No full textTraditionally biological or genetic mutations have been used to distinguish cancer from normal tissues and to stratify cancers into molecular subtypes, resulting in successful targeted therapies. In a similar way, the cancer mechanical phenotype holds significant promise as a potential biomarker as cancers show altered biophysical phenotypes at the cellular and tissue length scales. However, translating these biophysical traits into cellular function or physiological traits as druggable targets remains challenging. Recent work has demonstrated that modulation of the microenvironment stiffness can promote metabolic rewiring which in turn is linked to cancer invasion. Metabolic plasticity is known to be a “hallmark of cancer,” as cancer cells must undergo metabolic evolution to survive or adapt to new organ microenvironments. Additionally, the tumor metabolic microenvironment regulates the efficacy of immunotherapies. Therefore, a promising nascent research direction is the investigation of the balance between tissue mechanics and metabolism, its potential dysregulation during metastatic progression, and its role in response to cancer treatments. The overall goal of this research is to decipher the interplay of cancer mechanobiology and metabolism in metastatic disease
“POSSESSING A NATION”: CAPITALISM, LABOR, AND THE BUILDING OF THE U.S. GATEKEEPING STATE, 1865-1924
No full textScholars have long sought to explain how and why the United States transformed from a nation with virtually “open doors'' for global immigration into a nation with a closed “gate.” While scholars of immigration differ on just how open the United States was prior to the Civil War, they generally agree that between the late nineteenth century and the early 1920s the federal government, which had traditionally encouraged immigration as an essential ingredient in the expansion of the nation’s economy, became a massive “gatekeeping” state, excluding most of the world’s population. Historians have analyzed why the building and guarding of a national gate became one of the federal government’s essential roles in the late nineteenth and early twentieth century. They have mostly focused on the important role played by racial and demographic arguments against immigration and immigrants. This interpretation alone does not fully explain why the United States, whose capitalist engine relied on the labor of tens of millions of immigrants, would close its doors during the nation’s rapid period of economic growth and expansion at the turn of the century.“Possessing a Nation” explains why the United States closed its borders to most of the world’s population, by reconstructing a five-decade long debate (1864 to 1924) among workers, capitalists, politicians, and immigrants over the boundaries of America’s volatile and expansive capitalist social order. It analyzes how the building of a gatekeeping state, and the transformation of the U.S. into an exclusionary nation, entailed the creation of a gatekeeping economy. I argue that the closing of the nation’s borders went hand in hand with the invention, by labor leaders, rank and file workers, and their allies, of a protected national economic order which privileged the position of white workers within a global labor and racial hierarchy and necessitated permanent federal protection. As I demonstrate, the carving out of a national political economy and working class from an international order took shape through the highly contested formation and implementation of federal immigration laws that established the legal, political and ideological framework of the U.S. gatekeeping state. These include the Alien Contract Labor Laws (1885 and 1890); Chinese Exclusion Acts (1882, 1888, 1894, 1902); Immigration Act (1891); Immigration Restriction Act (1917); Emergency Quota Act (1921); and the Johnson Reed Act (1924). The construction of a federal gate, and gatekeeping economy, was the outcome of a protracted class conflict over the racial and political boundaries of a domestic labor market and capitalist social order which was profoundly shaped by global immigration. Each of this project’s five archive-based chapters reconstructs how this conflict pitted shifting political formations of protectionist labor leaders, workers, and their elite partners against dynamic coalitions of business interests, immigrants, diplomats and pro-immigration politicians and intellectuals who advocated for a more open domestic economy
Dancing In and Out of Place: Black Concert Dance Histories and New York City's Clark Center, 1959-1989
No full textThis dissertation is the first scholarly study of Clark Center for the Performing Arts, an important New York City dance studio and school. Founded in 1959 as a place for black gay choreographer Alvin Ailey to formalize his modern dance company, Clark Center began in a YWCA in midtown Manhattan. Over the next thirty years, it grew to offer a robust slate of intentionally low-priced dance classes to dancers of many walks of life. Specifically, Clark Center aimed to resource African American dancers and emerging choreographers who sought to establish themselves professionally and start companies. Affiliated teachers and choreographers of note included Thelma Hill, Dianne McIntyre, Pepsi Bethel, Charles Moore, and Jawole Willa Jo Zollar.
Using primary-source archival records and oral-history interviews, this project chronicles the history of Clark Center and analyzes its social, political, and cultural significance. Theorizing that Clark Center’s history has been obscured in the discourse of “uptown dance” and “downtown dance,” I coin “midtown dance.” This new paradigm highlights a network of dance studios in midtown Manhattan that offered a pluralistic array of dance forms to a diverse group of people. Clark Center also birthed Playwrights Horizons in the early 1970s, a theater organization that split off soon after its founding. As the Times Square area was subjected to “clean up” efforts, the arts became a tool of redevelopment. Playwrights Horizons inaugurated one such redevelopment project when it moved to Theatre Row, a new block of off-/off-Broadway theaters. After a years-long attempt to establish a dance venue there, Clark Center shuttered in 1989, its mixedness rendered incommensurate with the increasingly homogenized region.
This project is especially attuned to the politics of black concert dance extended through Clark Center and that live on today. It argues that Clark Center modeled an alternative, “black-centric” version of racial integration, one that did not undercut black identities. Moreover, it posits that engagement with African-diasporic dance forms at Clark Center engendered in black students expanded conceptions of themselves as diasporically African and historically American. Deploying and contributing to Black Performance Theory, dancing at Clark Center is shown to be black self-making and black world-making
Electronic Supporting Data: Aromatic Wall Extension of Glycoluril-Derived Molecular Clips Enhances Binding of Planar Aromatic Dyes
No full textSee the Supporting Information document.We report the synthesis and characterization of a new methylene bridged glycoluril dimer featuring anthracene walls (H2). H2 displays good solubility in water (≥7 mM) but undergoes self-association at concentrations above 2 mM. 1H NMR experiments establish that H2 binds cationic dyes inside its cavity with a -stacked geometry that places the cationic residues at the ureidyl carbonyl portals of H2. The binding constants of both naphthalene-walled clip H1 and anthracene-walled clip H2 toward a panel of dyes were measured by direct or competitive UV/Vis or fluorescence titrations in phosphate buffered saline (PBS). Binding constants cover the range from 103 – 108 M-1. Dyes that feature cationic NMe2 groups bind more strongly than analogous dyes with cationic NH2 groups. We find that pi-extension of the aromatic walls from H1 to H2 generally results in an ≈ 10-fold increase in binding affinity. Host•guest complexes of H1 and H2 with planar cationic dyes benefit from substantial cation-pi interactions.We thank the National Science Foundation (CHE-1807486) for past financial support. We thank the National Institute of General Medical Sciences of the National Institutes of Health (R35GM153362) for current financial support of this project.https://doi.org/10.1002/chem.20250217
Autistic Joy on Tumblr
No full textTumblr is a unique social media site with a very distinct culture and design. Many of its users are autistic or otherwise neurodivergent, queer or disabled. The site offers its users more control over the content see and other forms of personalization than other sites, and many users are there to pursue niche interests. Although the site and its culture are different from other social media platforms, it has brought and continues to bring joy to many people. Tumblr has largely been overlooked in the academic literature. This study uses semi-structured interviews and thematic analysis to examine autistic adult Tumblr users’ positive and negative experiences on the site, as well as what strategies they employ to seek out the former and avoid the latter, focusing on positive experiences overall. The themes that emerged included the presence of communities with shared interests and identities, the ability to find useful information and resources, an overall lack of pressure to pursue fame and engagement, and aspects of the web design like the tagging system
Examining the Role of Speech Rhythm in Newborn Language Discrimination Through Machine Learning and Biologically Informed Models of Speech Processing
No full textNewborns are sensitive to the difference between the speech of some languages but not others, a phenomenon referred to as early language discrimination. While this is commonly attributed to their sensitivity to the temporal rhythm in speech, it has never been systematically tested. In this thesis, I explored the behavioral phenomenon of language discrimination through a series of simulations using machine learning models. In addition to typical models directly drawn from machine learning, I also introduced a model that is grounded in auditory neuroscience through differentiable programming.
Results from the traditional machine learning models suggest that rhythm was not necessary for any model to perform language discrimination in a humanlike manner, which implied that other mechanisms relying on global statistics alone could be possible for language discrimination and potentially used by humans during behavioral tests. Additionally, with the differentiable model with auditory neuroscience constraints, while the model uses rhythm to perform language discrimination, the range of rhythm was much faster than what is associated with syllable rhythm. These results have implications about newborn language perception and language acquisition that follows, and may be used to drive the design of future infant studies. Additionally, the application of differentiable programming to introduce intuitions and constraints from neuroscience and cognition offers a new path of manipulating deep neural networks in the study of neural and cognitive modeling
POISSON LIMIT THEOREMS IN DYNAMICAL SYSTEMS AND ERGODIC SUMS OF NON-INTEGRABLE OBSERVABLES
No full textThis thesis investigates statistical properties of rare events in dynamical systems, with a partic-ular focus on recurrence statistics and limit laws for ergodic sums of heavy-tailed observables.
A central theme is the Poisson Limit Theorem (PLT), which describes the limiting distribu-
tion of return times to small sets, and its role in establishing asymptotics for extreme events.
Concretely, this thesis addresses the following topics:
First, we construct examples of non-mixing dynamical systems that still satisfy the PLT, demon-
strating that strong statistical properties can persist even in the absence of mixing. This is
significant because, until now, all known systems satisfying the PLT have been mixing, with
existing proofs relying on mixing assumptions.
Second, we establish strong limit laws for ergodic sums of non-integrable observables. In such
cases, large fluctuations due to close visits to the singularity typically obstruct strong limit laws.
To address this, we employ trimming, a well-known probabilistic technique, by systematically
removing the closest visits to the singularity. We prove trimmed strong laws for irrational
rotations, emphasizing once more that our results seem to be the first of their kind that do not
rely on mixing.
We also present in the conclusion some natural questions and directions a future research,
including hitting time statistics, similar to the PLT setting, and distributional limit theorems
for ergodic sums of non-integrable observables