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Cortical Functional Organization in Early Childhood
Full text linkThe advent of connectivity-based methods, particularly those utilizing spontaneous BOLD signals, has significantly advanced brain mapping and deepened our understanding of the human brain\u27s functional architecture. While prior research has explored functional organization in early childhood, most studies have focused on coarse, group-level distinctions aligned with adult literature, often within narrow age ranges. This dissertation extends these investigations by examining cortical functional organization in greater detail among healthy infants and toddlers aged 1 to 5 years. Chapter 1 employs spontaneous BOLD signals in sleeping infants and toddlers to derive a group-level functional organization at the resolution of areas and networks. It compares infant/toddler area parcellations with existing adult and infant atlases to assess alignment and potential biases in analytical approaches. Additionally, it presents both coarse and fine-grained functional network divisions for a group-average connectome at approximately 2 years of age. Chapter 2 investigates the applicability of adult-derived functional network divisions to infant/toddler functional connectivity (FC), identifying regions with early adult-like organization and linking them to interindividual variability in adults. Chapter 3 introduces a vertex-level, individualized approach to delineate functional networks using a template-matching method, addressing limitations of group-average analyses. This chapter also proposes an alternative method for generating group-level network templates without explicit data alignment, enabling more precise fine-scale network mapping and age-related comparisons
Sown in Soil: Black Mississippi Landowners, Heirs Property, and New South Neoliberalism
Full text linkThis thesis examines the history of how Black Mississippians in the greater Madison County area have conceptualized land ownership since circa 1970 in order to understand how acquiring land has historically been seen as a significant source of financial, social, and mental security for Black folks in rural Madison County. By looking at oral history interviews from mostly the Garrett family and other Black Madison County citizens and archival materials, one will see how connection to land and place—despite the land being listed under heirs’ property— is the underpinning of familial affinity and association. To understand how heirs’ property is understood amongst scholars, one must delve into the most relevant literature surrounding the theme
Soft, Adhesive Dry Electrodes for Improved Electrophysiological Signal Acquisition with Motion Tolerance and Long-Term-Recoverability
Full text linkSoft electronic devices and sensors have seen substantial interest devoted to them for the purpose of recording and analyzing various electrophysiological signals including for the use of electrocardiography (ECG), electromyography (EMG), and electroencephalography (EEG). Dry electrodes specifically have enormous potential compared to traditional commercial electrodes for long-term, real-time monitoring of biopotential activity. Gel-based commercial electrodes have notable drawbacks such as limited flexibility, skin irritation that decreases comfort, inconsistent signal quality due to poor conformal contact, and degraded signal quality over long-term monitoring due to drying out.
Herein, we report a soft, adhesive dry electrode that utilizes chemical additives to promote its electrical, adhesive, and mechanical properties to collect stable, low-noise electrophysiological signals through a low-cost fabrication process. Dry electrodes fabricated with poly(3,4-ethylenediox-ythiophene) polystyrenesulfonate (PEDOT:PSS) as a conductive polymer offer such advantages as the ability to conform to skin deformations, a lighter weight than traditional electrodes, reduction of motion artifacts, and improved comfort all without the use of gel; the absence of gel negates issues previously mentioned such as skin irritation or having the electrode dry out. Furthermore, PEDOT:PSS-based electrodes have tunable stretchability, conductivity, and adhesion properties that are optimal for flexible bioelectronics and wearable devices.
These electrodes, referred to as 3PT, can record reliable, clean biopotential signals with an increased signal-to-noise (SNR) ratio than traditional electrodes. Experimentation shows that the fabricated electrodes offer motion-tolerant-recording and can undergo moisture-induced recovery to regain its optimal properties and restore its performance for reliable use. Our flexible and adhesive novel dry electrode is a promising alternative to commercial electrodes due to its low-cost manufacturing, adhesive properties, comfortability, and improved signal strength of biopotential activities
Predicting Which Genes Will Respond to Transcription Factor Perturbation
No full textA fundamental issue in mapping regulatory networks between transcription factors and their target genes is the poor overlap between the set of genes bound by a given transcription factor (TF), and the set of genes that are differentially expressed after knocking out or overexpressing the same TF. We began with the hypothesis that to predict whether a gene will respond to perturbation of a TF, it is important to not only consider whether that TF is bound at the gene’s promoter, but also whether other TFs bind at the same promoter.
In this work, we propose a novel modeling procedure to better predict gene expression changes in Saccharomyces cerevisiae following TF overexpression by considering the binding data of the perturbed TF and additional pairwise TF-TF interactions.
Using binding data from Calling Cards experiments and perturbation response data from the McIsaac ZEV overexpression dataset, we created 101 models for predicting which genes will respond to perturbations of 101 different TFs. The input features for these models, which are linear in their parameters, include the binding profile of the perturbed TF and 119 interaction terms between the perturbed TF and each other TF. A three-step pipeline employing bootstrapping and nested cross-validated LASSO modeling was used to identify high-confidence predictors that affect the perturbation response in a consistent direction.
Our findings suggest that these TF interactions often contribute better explanatory power than individual binding signals alone. Additionally, several recovered interaction terms align with known biological interactions such as GCR2:TYE7 and FKH1:FKH2, supporting the validity of our approach in identifying both known and novel regulatory relationships. These results provide additional support for proposed regulatory mechanisms and offer directions for future exploration. Thus, our work introduces a robust procedure for identifying biologically meaningful TF–TF interactions and improving the predictability of gene expression from TF binding data
On the H-property for Step-graphons: Residual Case
Full text linkWe investigate the H-property for step-graphons. Specifically, we sample graphs Gn on n nodes from a step-graphon and evaluate the probability that Gn has a Hamiltonian decomposition in the asymptotic regime as n → ∞. It has been shown in Belabbas and Chen (2023); Belabbas et al. (2021) that for almost all step-graphons, this probability converges to either zero or one. We focus in this paper on the residual case where the zero-one law does not apply. We show that the limit of the probability still exists and provide an explicit expression of it. We present a complete proof of the result and validate it through numerical studies
Reducing Measurement Error in Three-Point Bend Test Using Linear Gradient Correction Model
Full text linkEndovascular devices like catheters feature non-uniform flexural rigidity (EI) profiles (flexi- ble tip, stiff shaft) crucial for navigation and pushability. Standard three-point bend analysis (assuming uniform stiffness) yields inaccurate apparent rigidity (B0) for these graded devices, especially in transition zones. This inaccuracy hinders device comparison, clinical selection, and predictive modeling. This thesis develops and validates a correction model for three-point bend tests aimed at improving local flexural rigidity accuracy for devices with varying stiffness, particularly those exhibiting transition zones similar to logistic profiles. The model assumes a linear gradient in rigidity (B(x) = Bm(1 + 2mx/L)) across the test span L. Solving the governing equation yields a correction factor W (m) relating true midpoint rigidity (Bm) to apparent rigidity via Bm = B0W (m). The gradient parameter m is estimated numerically via finite differences on sequential B0 measurements. The model’s performance was evaluated through numerical simulations using known true stiffness profiles. For ideal linear profiles, the correction accurately recovered the true stiffness (Bm ≈ Btrue), confirming the model’s theoretical validity. For non-linear logistic profiles, chosen as representative examples of catheter transitions, the correction significantly reduced viii percentage error compared to uncorrected B0, especially in high-gradient regions. Sensitivity analyses showed accuracy improves with smaller test spacing (better m estimation) but decreases for steeper profiles or profiles deviating significantly from the underlying linear assumption. Application to experimental catheter data demonstrated feasibility, yielding quantifiable corrections and a more representative local stiffness profile. In conclusion, the linear gradient model offers a computationally inexpensive method to potentially improve flexural rigidity characterization for devices whose stiffness profiles are reasonably approximated by the model’s assumptions (e.g., smooth, logistic-like transitions). While it can provide more reliable mechanical data under these conditions, aiding clinical decisions, device design, and modeling, its necessity and effectiveness may be limited for devices with more complex or abrupt stiffness changes
Transmutation
Full text linkMy artistic practice is about change itself. I am inspired by the doubling and layering effects that came out of Surrealist Photography. Scale, fracture, and doubling are intentional components of my process. I combine those methods to create complex works of art, focusing on the untamable light that I hope to capture when making my images, which often are self portraits. Poetry is an integral element of this thesis text as well as my art making process. Through my poetic work I hope to offer my audience a glimpse into how I see and experience the world. This thesis text takes readers on a journey through several key elements of my practice: from the importance of chance in how I make photographs, to my use of scalar confusion, to the role of fracture and fragment, and finally, to my focus on doubling effects
Imaginary Friends: Engaging the Unconscious Mind through Picture Books
Full text link“Imaginary Friends” investigates the potential of the ‘imaginary friend’ as a narrative device in picture book storytelling. By combining the research of Marjorie Taylor on ‘imaginary companions’ and Lois Rostow Kuznets on ‘toy animals’ in literature, I seek to give form to the concept of the imaginary friend, to then explore the phenomenon further by delving into the intellectual heritage of the imaginary and the unconscious mind. To explain how the imaginary friend works as a visual metaphor in illustrated narratives, I borrow principles of image-making and their effect on children, as discussed by Martin Salisbury, Morag Styles, and Molly Bang. Through examples by picture book makers Maurice Sendak, who uses the device in the form of the ‘wild thing’ in Where the Wild Things Are (1963), and Shaun Tan, in the form of the ’creature’ in Eric (2010), I illuminate the imaginary friend at work. Following a thread of scientific theory into artistic practice, while analyzing the benefits of imaginative play and fantasy in readers by Gianni Rodari and J.R.R. Tolkien, I find the value of the liminal nature of the imaginary friend in children’s literature. Ultimately, I argue for its function as a doorway for young readers to engage with the world of picture books in unique and insightful ways
On Drawings of Dragons
No full textFantasy functions in a strange ebb and flow—constantly negotiating with truth, reality, history, and culture. This essay interrogates visual material which largely accompanies literature within the fantasy genre, a subgenre of speculative fiction typically set in magical worlds apart from our own. It situates the historical and potential roles of fantasy illustration and imagery in the cultural landscape by setting the ideas of visual culture scholars, fantasy historians and theorists, and essential fantasy and science fiction authors J.R.R. Tolkien and Ursula K. LeGuin in conversation with visual and contextual examination of examples of popular fantasy imagery including the work Howard Pyle (1853-1911) and the 2022 debut work of author-illustrator duo Nadia Shammas and Sara Alfageeh. Ultimately, it argues that fantasy imagery—a basic and essential mode of human cultural expression—is capable of providing both escape from and conversation with historical and modern issues. This essay argues for the necessity of critically examination not only of the historical sources of fantasy tropes and imagery, but the understanding of its unique staying power and very tangible influence on our world, our culture, and ourselves
Digital and Physical Spaces: All at Once
Full text linkIn this thesis, I explore our experience of digital and physical spaces in the ever-increasing presence of technology. By investigating the intersections of these spaces, I focus on how our experiences in the physical world are processed through the digital space, to re-merge in lived spaces. Through digital collage paintings, I explore how assisted chance and machine destruction can be productive in the formation of space that is not possible on the screen. By using the drop shadow as primary content, my work takes on the arrangements of surface and space—rather than the requirements of the physical world. In addition, I use the physicality of paint to concretize the digital image into physical space and insert myself between both the digital and the physical world. Through my work, I hope to call attention to the way we process the digital space and physical space, all at once