50107 research outputs found
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Anisotropic hydrogel microelectrodes for intraspinal neural recordings in vivo
No full textCreating durable, motion-compliant neural interfaces is crucial for accessing dynamic tissues under in vivo conditions and linking neural activity with behaviors. Utilizing the self-alignment of nano-fillers in a polymeric matrix under repetitive tension, here, we introduce conductive carbon nanotubes with high aspect ratios into semi-crystalline polyvinyl alcohol hydrogels, and create electrically anisotropic percolation pathways through cyclic stretching. The resulting anisotropic hydrogel fibers (diameter of 187 ± 13 µm) exhibit fatigue resistance (up to 20,000 cycles at 20% strain) with a stretchability of 64.5 ± 7.9% and low electrochemical impedance (33.20 ± 9.27 kΩ @ 1 kHz in 1 cm length). We observe the reconstructed nanofillers’ axial alignment and a corresponding anisotropic impedance decrease along the direction of cyclic stretching. We fabricate fiber-shaped hydrogels into bioelectronic devices and implant them into wild-type and transgenic Thy1::ChR2-EYFP mice to record electromyographic signals from muscles in anesthetized and freely moving conditions. These hydrogel fibers effectively enable the simultaneous recording of electrical signals from ventral spinal cord neurons and the tibialis anterior muscles during optogenetic stimulation. Importantly, the devices maintain functionality in intraspinal electrophysiology recordings over eight months after implantation, demonstrating their durability and potential for long-term monitoring in neurophysiological studies
Using balancing weights to compare performance across facilities providing family planning services in Kenya
No full textAssessing the extent to which the quality of family planning (FP) delivery in facilities makes a difference for key outcomes such as service satisfaction or contraceptive discontinuation is of key interest to the family planning field. However, assessment of this relationship is methodologically challenging due to differences in populations served across facilities. Furthermore, data that connect facilities to the populations served are limited. We use novel data from the Performance Monitoring for Action (PMA) project and a new methodological approach to examine the relationship between facility level characteristics and FP outcomes. The PMA data consist of facility surveys and client exit interviews, and capture women’s FP outcomes and include information on characteristics of the individual woman, the facility where the woman obtained her family planning services, and follow-up information on contraceptive use. We use a design-based direct standardization method to balance the distribution of populations served across facilities while controlling for the additional variability induced by the balancing weights. We find significant evidence of variation in FP outcomes across facilities that cannot be accounted for by differences in women characteristics. The type of facility (e.g., dispensary), their size, the proportion of staff present, and whether the facility was public were associated with more positive service satisfaction. A higher ratio of staff to FP visits was predictive of lower contraceptive discontinuation
The Quiet Encroachment: Stories of Everyday Resistance
No full textThe Quiet Encroachment: Stories of Everyday Resistance is an interdisciplinary exhibition combining sculptural masks, video installations, and narratives to explore the intersection of gender, resistance, and identity in the context of authoritarian control. Utilizing the entirety of LEG Gallery, the exhibition examines how Iranian women confront societal and state-imposed restrictions through everyday acts of defiance.
Inspired by Suzankari (سوزن دوزی), a traditional needlework practice from southern Iran, the exhibition reinterprets its elements—thread, and mirrors—by using fragmented mirrors to symbolize the fragility and disjointed realities of life under surveillance. These mirrors, stitched together with thread, represent the collective strength formed through small, individual acts of resistance.
The gallery space features sculptural masks displayed on metal stands shaped like human figures, paired with video installations showing the process of sewing masks. The videos are accompanied by women’s voices narrating their personal stories of navigating and resisting restrictive systems. The juxtaposition of fragmented mirrors and narrated stories emphasizes the tension between private and public identities and the labor required to reclaim agency.
This exhibition highlights the strategies women use to challenge oppressive systems while creating a dialogue about the significance of everyday resistance. By blending traditional crafts with contemporary storytelling, The Quiet Encroachment encourages viewers to engage with the resilience and creativity of these women’s lives.Master of Fine Arts (M.F.A.)2026-02-0
Nature-Based Educational Settings for Promoting Prosocial Behaviors for Children with Autism Spectrum Disorder in Preschool: A Mixed Methods Case Study
No full textThe interaction between a preschool Nature Based Educational (NBE) setting and children with Autism Spectrum Disorder (ASD) prosocial skill building has yet to be studied in-depth, and the potential of NBE settings for this specific diagnosis in early childhood settings has yet to be explored (Wilson, 1994). Understanding the ideal environment for someone with ASD is a critical issue for providing impactful services and schooling, as the core deficit of prosocial skills varies across different environments. Prosocial skills are vital because they affect access to the social and physical environment. This is especially important for kids with ASD who struggle with social skills. By offering an environment that is both sensory friendly and increases low-stakes social interactions, NBE has the potential to be an accessible environment for learning prosocial skills. This research explores the relationship between children with ASD prosocial skill development and NBE using a Descriptive Case Study using Mixed Methods Grounded Theory (MM-GT) with concurrent Triangulation design (Laws, 2023). Qualitative methods are based on constructivist epistemology, and quantitative methods are based on post-positivist epistemology, leading to the triangulation of equal
mixing of methods and increased reliability and validity of findings. This study addresses the research question, “Does NBE help support the prosocial skill development for
children with ASD in preschool, and if so, in what ways?” Through qualitative analysis outdoors (Appendix H), I found children outdoors's flexible access to people, places, objects and self- establishing an Emotional Tenor of Contentment (Appendix I). Through quantitative analysis, I found that while the social climate of the class was stable indoors and outdoors, children engaged in more prosocial behaviors outdoors. Thus, the emotional tenor of contentment that children felt when outdoors set the stage for prosocial use and growth by creating opportunities for prosocial interactions. In summary, the Grounded Theory was ‘flexible access that children in NBE with ASD have to people, places, and objects, and self offers children an Emotional Tenor of Contentment, which in turn allows for opportunities for prosocial growth.’ An Autistic Researcher completed this study.Doctor of Philosophy (Ph.D.
Teachers' Perceptions of Supporting Friendships for Children with Disabilities in Early Childhood Classrooms
No full textChildren’s social relationships during early childhood (EC) years are vital to developing their social lives. However, there is no accepted distinction between peer relationships and
friendship for young children, especially Children with Disabilities (CWD), who often experience difficulties developing relationships. Research has shown that teachers can support
social relationships, such as friendship, between children with and without disabilities in inclusive classrooms. Many of those intervention programs and strategies focused on social-
emotional support involve teachers; However, there is limited information about what teachers think about friendship for Children with Disabilities and how they perceive their efficacy in supporting friendships in inclusive EC classrooms. Thus, using semi-structured interviews and thematic analysis, the current study will address the following research questions: (a) What are EC teachers’ perceptions of friendship development for Children with Disabilities? (b) What are EC teachers’ perceptions regarding their efficacy in supporting friendship development for Children with Disabilities? and (c) What strategies do EC teachers use to support friendships for Children with Disabilities? Four themes emerged from thematic analysis, including 1) the classroom is a social community; 2) Children with Disabilities have social barriers that affect social relationships with peers; 3) the teacher is a vital part of the student's whole social experience and provides a safe social environment, and 4) friendship is a distinct relationship from peer relationships. The researcher found that consistent with previous research, teachers’ perception about working with Children with Disabilities, friendship, and friendship for Children with Disabilities influenced their confidence in implementing friendship teaching practices in the classroom, especially in supporting Children with Disabilities.Doctor of Philosophy (Ph.D.
The Discovery and Classification of Novel Viruses from the Giant Virus Phylum Nucleocytoviricota (NCV)
No full textThe phylum Nucleocytoviricota (NCV), encompassing a diverse array of large and giant viruses, primarily comprises double-stranded DNA viruses that infect a wide range of eukaryotic organisms. Emerging evidence suggests a significant role of Horizontal Gene Transfer (HGT) within members of the NCV phylum, potentially enhancing their adaptability through the acquisition of novel genes and functions. However, the functional implications of these transferred genes remain poorly understood, necessitating further research.
My project used recent metagenome-assembled genomes (MAGs) from the Barre Woods site at Harvard Forest. MAGs were formed using two different methods involving assembly of individual metagenomes and the combined assembly of all 6 metagenomes. The comparison between individual and co-assembled data revealed that the integration of both datasets provides a more comprehensive depiction of the genomic landscape.
I developed a pipeline to help predict potential HGT events to better understand genetic exchange mechanisms within the NCV phylum. I identified horizontal gene transfer candidates related to the new viral MAGs from Barre Woods. Matches of the viral MAGs to bacterial genomes in NCBI involved many instances of misclassification of viral genomes as bacteria or viral - bacterial horizontal gene transfer candidates were not further analyzed. The Perivirus MAG has large contiguous matches to genome projects of the snail, Elysia margianta and fungus, Rhizophagus. The Perivirus genes matching the snail genome were on small contigs with a different read depth than the main chromosomal regions of the snail suggesting that a Perivirus relative may have been infecting the snail at the time DNA was isolated. This provides evidence that one possible host for the Perivirus are snails commonly found in forests. The Perivus genes matched genome regions from several Rhizophagus species, suggesting large-scale virus gene integration in an ancestor of these species. The pipeline identified a significant number of ANK genes in a Pimascovirales NCV MAGs that have homology matches to two genes from aphids. I proposed that the ANK gene in the NCV is a result of a HGT from the aphids to the NCV, followed by a gene duplication event that leads to the repeats of the ANK gene.Master of Science (M.S.
Shifting Perspectives about Housing Issues in Rural Communities: Scenario Planning for Housing Development
No full textHousing shortages in the United States affect all persons but are especially impactful to low-income families who desire to move to high-opportunity neighborhoods. Housing is often seen as an intractable dilemma because of the emotional component involved with people wanting to preserve their neighborhoods as the same style to when they moved in. Scenario planning is an excellent tool for the modern planner at solving such intractable dilemmas. However, there is a gap in the literature regarding using scenario planning in smaller rural communities as opposed to regional scales or large cities. This does smaller areas a disservice as they could benefit from having tools to apply scenario planning methodology to the issues they face. The case study and proposed case study as part of this thesis work is to propose ideas for how scenario planning can be applied on a small scale to be replicated by other small communities. Both case studies were chosen to be relatively comparable in housing dilemma, one a very rural town in the Pioneer Valley, and the other being larger but facing similar conditions. The resulting methodology for housing enthusiasts to apply the methods in this paper to their own communities to replicate and have a productive conversation about housing.The research was done in partnership with the Lincoln Institute of Land Policy.Master of Arts (M.A.
THE INFLUENCE OF CHAIN ARCHITECTURE ON THE ASSEMBLY OF BLOCK COPOLYMERS AT THE INTERFACE AND IN THIN FILM
No full textBlock copolymers (BCPs) can self-assemble at the interface between two immiscible phases, with each block segregating into its compatible phase. The interfacial assemblies of BCP can effectively screen the unfavorable interaction between the phases, significantly reducing interfacial tension. The phase can vary from small molecule (e.g., water and oil) to macromolecules (e.g., homopolymer). In Chapter 1 and Appendix A, we first presented the in-situ conversion strategy, where the hydrophobic-hydrophobic BCPs are converted to hydrophobic-hydrophilic BCP directly at the water-oil interface, leading to significant reduction in interfacial tension. In Chapter 2 and Appendix B, by employing in situ conversion with star BCP architecture, we achieved self-wrinkles at fluids interface. The wrinkle patterns were programmed by controlling the interfacial assembly of star BCP. In Chapter 3 and Appendix C, the phase behaviors of star BCP at fluids interface was studied by transferring the interfacial assemblies with silicon wafers. The morphology of transferred film was found to be highly dependent on the in situ conversion degree, molecular weight, volume fraction of each block and the BCP architecture. At homopolymer-homopolymer interface, BCP act as efficient compatibilizers. In Chapter 4 and Appendix D, we systemically investigated the interfacial conformation and compatibilization of star BCP at homopolymer interface. We revealed that increasing the arm numbers can enhance the binding energy per molecule, leading to higher compatibilization efficiency. In Chapter 5 and Appendix E, we developed Janus bottlebrush compatibilizers, consisting of two homopolymer chains randomly distributed along the linear backbone. At equilibrium, these side chains orient in opposite directions, maximizing binding energy while minimizing steric hindrance. In Chapter 6 and Appendix F, we also investigated the self-assemblies of bottlebrush BCP in thin films, showing the thin film morphology was highly dependent on the architecture (including degree of polymerization of backbone and grafting density) and the depth of the thin film.Army Research Office under Contract No. W911NF-17-1-0003.Air Force Office of Scientific Research under award number FA9550-21-1-0388.Doctor of Philosophy (Ph.D.
The Effects Of Collective Curation Of Digital Learning Materials On Students' Social-Emotional Needs, Motivation, And Learning
No full textThe digital age has brought about a new era in which free, high-quality learning materials are available online, and students can access them anytime and from anywhere with an Internet connection. The textbook is no longer the sole resource available to students. Searching, selecting, organizing, and deriving meaning from online resources (digital curation) has become an important 21st-century skill, one that has the potential to motivate and engage learners.
This mixed methods study, conducted in secondary school environmental science classes, used Self-Determination Theory to explore the impact of collective digital curation on student autonomous motivation. The study also analyzed student notes and unit tests to assess the effects of collective digital curation on student cognition and learning. Additionally, students were surveyed to explore their perceptions of the properties and features of textbook assignments compared with curation assignments.
This study found that students did not strongly prefer either textbook assignments or curation projects, recognizing that each had its advantages and disadvantages. While the textbook provided a well-organized resource aligned with course objectives, curation offered a collaborative process that allowed students to customize their learning experiences to explore relevant topics to learn more comprehensively about them. Although curation better satisfied students’ need for autonomy and relatedness, it did not better meet their needs for competence, as they equated competence with success on the unit exam, which they believed primarily assessed rote knowledge covered in the textbook.
The findings indicated that external controlling factors primarily motivated students to complete the textbook and curation assignments. However, curation offered more opportunities for students to engage autonomously with enjoyable, engaging content that allowed them to explore topics more deeply and comprehensively. Lastly, curation positively impacted learning outcomes, as evidenced by students’ improved performance on multiple-choice questions assessing basic understanding and open-response questions evaluating deeper comprehension. The results also indicate that curation could decrease the class performance gap by primarily benefiting lower-performing students.
This study underscores the need for further research on the role of collective curation projects in education. It demonstrates that such projects offer unique learning opportunities for students to collectively and autonomously learn more deeply and comprehensively about topics in modern digital environments. However, integrating curation into traditional classrooms, which tend to be test-focused and prioritize unified, homogeneous rote learning, is challenging. Future research should focus on how best to use curation to autonomously motivate students to learn more deeply and comprehensively about topics. Educators need to restructure classes and curricula to integrate collective curation projects that can foster autonomous online learning while teaching valuable digital literacy and research skills that will benefit students in future education and careers. This study provides a solid foundation on the effects of curation on student motivation and learning, which researchers can build upon and educators can use to positively affect student learning and motivation.Doctor of Philosophy (Ph.D.
HIGH-SPEED VISION PROCESSING AND COMPUTATION USING MEMRISTOR- BASED CELLULAR NEURAL NETWORKS
No full textNeuromorphic computing algorithms and brain-inspired architectures hold promise to move beyond the current limitations of contemporary von Neumann architectures that are
hindering current Artificial Intelligence (AI) implementations in terms of processing speeds and power consumption. The Cellular Neural Network (CeNN) is one such bio-inspired architecture that allows for massively parallel, analog computing schemes for high-speed image processing.
The network is composed of simple, repeating processing elements referred to as cells and takes advantage of reprogrammable local connectivity for direct neighborhood interactions as well as propagating global dynamics to achieve a wide variety of applications. The first section will introduce the network fundamentals and underlying principles of
network dynamics. Based off these fundamentals, a CeNN GUI software package with a digital twin simulator is written in python. The simulator is designed and tested for a wide variety of applications based off suggested hardware parameters. Simulated image and video processing approaching 100,000 frames per second are shown. Noisy image and video processing is also discussed, simulating the consequences of mismatch and variance in a fabricated network. Computational simulations for solving partial differential equations further demonstrate network robustness and capabilities. These digital twin simulations inform us on network performance and provide insight into the potential behavior of fabricated hardware networks. The second section focuses on the design and measurement of a prototype 5×5 hardware network based on pure CMOS using the TSMC 65nm process node. Edge detection and vertical/horizontal line detection algorithms are run demonstrating processing speeds greater than 20,000 frames per second. Performance merits are presented and compared to prior state of the art implementations.
Finally, emerging Ta/HfOx drift memristor devices are introduced and the benefits of using such devices for neural networks (NN) are discussed. These two terminal devices are
implemented into a “bridge synapse” architecture for efficient weight storage and intrinsic weight multiplication. A board-level CeNN prototype is built around these memristive devices and used to demonstrate horizontal line detection.
This dissertation discusses and contributes to the development of massively parallel, low-power, analog NN hardware with a focus on CeNNs. The CeNN digital twin provides a means
for easy network modelling in software and proof of concept. The fabrication of hardware and testing of a pure CMOS IC as well as the board-level memristor-based implementation further explore and demonstrate the feasibility of parallel, reprogrammable network architectures for high-speed, analog processing.Doctor of Philosophy (Ph.D.