Dartmouth Institute for Health Policy and Clinical Practice
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CUSTOMIZABLE VR DRIVING EXPERIENCES: BALANCING USER COMFORT AND INTERACTIVITY
Full text linkDriving games and vehicle simulations have been a prominent genre in the gaming world, thriving on traditional platforms like consoles and PCs. Despite the advances in virtual reality (VR) technology, the genre has seen limited success in VR, largely due to challenges in balancing user comfort, immersion, and the physical constraints of VR hardware. The primary issue arises from the conflicting goals of interactivity and comfort. While VR offers an immersive, high-speed experience with dynamic steering and rapid movements, these same elements often cause discomfort and cybersickness, undermining the very immersion that VR promises.
This research aims to address these challenges by investigating how customizable features within VR driving simulations can mitigate discomfort associated with fast movements and rapid steering while maintaining engagement. The study focuses on the impact of adjustable parameters, such as vehicle dynamics, visual adjustments, and environmental elements on user comfort and immersion. A key aspect of the study is understanding the trade-offs between user customization and maintaining the fast-paced, interactive nature of driving simulations.
User testing was conducted with a sample of participants, collecting both qualitative and quantitative data to explore how preferences for these features influence comfort and engagement. The results highlight the importance of providing customizable options that allow users to tailor their experience to their comfort levels, while also keeping the immersive, fast-paced qualities of the genre intact. Ultimately, this research offers insights into the design of VR driving simulations, suggesting that thoughtful customization can enhance comfort without sacrificing engagement, thus advancing the development of more accessible and enjoyable VR driving games
A WAVE-OPTICS BSDF FOR CORRELATED SCATTERERS
Full text linkIn this project, we present a wave optics bidirectional scattering distribution function(BSDF) for the material with a collection of scatterers, such as certain fabrics with pores or foggy glass, where the corona effect can be observed under strong light sources. This effect arises from the diffraction of individual scatterers and the interference between them. To describe this effect, we treat each scatterer as an aperture to calculate diffraction, while using a pair correlation function to represent their spatial relationships and calculate the interference. This two-level decomposition allows us to derive a BSDF that can control both the individual diffraction function and the interference function. Additionally, we extend this method to handle mixtures of different types of scatterers within a single system. Furthermore, we propose a practical strategy for importance sampling this BSDF and demonstrate the ability of our method to qualitatively reproduce the corona effect for several common materials
Deep Learning for Fine-Grained Digital Histopathology Image Analysis
Full text linkAs digital pathology becomes increasingly popular, it is critical to develop machine learning solutions to utilize this data. While other image modalities have seen exponential increases in methodology availability, the same has not been true for histopathology images. This is likely in part because histopathology whole slide images possess unique characteristics that prevent simply applying existing methods as-is.
In this thesis, we identify and propose solutions to 3 open problems with histopathology images: 1. large raw image size (up to 150,000×150,000 pixels in size), 2. low class-positivity (low ratio of positive to negative patches), and 3. limited image availability with existing images having weak or no labels. We address the large raw image size problem by designing a knowledge distillation-based approach to reduce computational cost significantly with a modest decrease in classification performance. The computational cost reductions are substantial enough to enable real time use in clinical scenarios. For the low class-positivity issue, we develop a custom view generation approach for self-supervised representation learning. This view generation approach takes advantage of the low class-positivity to increase possible view pairings and produce better classification outcomes. Lastly, we present an image generation approach using existing image-spatial transcriptomics pairs to generate synthetic histopathology patches. We demonstrate these generated patches are clinically useful through evaluations including nuclei distribution quantification and downstream tasks
Out of the Suitcase and Into the Bag: Rethinking Metaphors of Refugeehood in Yugoslav War Memoirs
No full textThe suitcase has become a staple trope in a variety of migration narratives since the early twentieth century. Travel, immigration, and forced displacement have all been packed into this same metaphor, which risks collapsing these distinct experiences. Moreover, while some refugees do bring suitcases with them, others pack their belongings in a variety of containers, and some are unable to bring along any possessions whatsoever. Looking beyond the suitcase, the goal of this thesis is to examine alternative representations of luggage in refugees’ stories. In doing so, I focus on two recent diaspora memoirs recounting experiences of the breakup of Yugoslavia, Sofija Stefanović’s Miss Ex Yugoslavia (2018) and Snežana Žabić’s Broken Records (2016). The former is a story of immigration and the latter of refugeehood, both memoirs concentrate on material objects, as well as the containers in which those objects are transported. Instead of defaulting to the suitcase metaphor, Stefanović and Žabić depict refugees as carrying a different kind of bag, one that is truly representative of the experience of refugeehood. Throughout this thesis, I will explore the differences between the suitcase and the “refugee bag,” examining the history of the two containers, their materiality, and the belongings carried within them
The Epistemological Violence of the Nahḍah: Hadīth ʿĪsā bin Hishām (1907) and the Specter of Inḥiṭāṭ
No full textThis thesis locates the reemergence of inḥiṭāṭ (decline) as an internal symptom and enduring residue of modernity, rather than its antithesis—a recursive structure within the epistemological grammar of the Nahḍah that exposes the limits, contradictions, and disavowed failures of reformist discourse. In doing so, I turn to Muḥammad al-Muwayliḥī’s Hadīth ʿĪsā bin Hishām (1907) and read how inḥiṭāṭ is positioned as a phenomenon that reflects what I call the paradox of reform, instead of a static historical condition; I read moments where the text captures the contradictions, breakdowns, and unintended consequences of the Nahḍah. Al-Muwayliḥī problematizes the linear narrative of decay and progress that structured much of Nahḍah thought, but rather than simply lamenting the failures of Ottoman institutions, the text suggests that inḥiṭāṭ and disruption are not antithetical to modernity but are constitutive of it. Ultimately, Hadīth ʿĪsā bin Hishām does not offer a singular resolution but instead exposes the Nahḍah as an ongoing and contested process, one that is marked by laḥẓāt (moments) in which the ideal of renewal is revealed to be unstable, incomplete, and perhaps even doomed
Mitochondrial Network Expansion and Loss During Oligodendrocyte Life and Death
No full textOligodendrocytes are the myelinating cells of the central nervous system, known for modulating signal transmission, refining neural circuits, and providing metabolic support to axons. Oligodendrocytes are generated throughout life from oligodendrocyte precursor cells (OPCs) and are damaged or lost in demyelinating and neurodegenerative diseases and age-related pathologies. Thus, understanding the cellular checkpoints that occur during the generation and degeneration of oligodendrocytes is crucial for maintaining their population in health and recovering it in disease and aging.
Using high-resolution optical imaging, I have discovered a dynamic redistribution and subcellular partitioning of mitochondria during oligodendrogenesis. Mitochondria transiently expanded towards the differentiating OPC processes upon myelin formation, before drastically declining in the periphery and recovering in the soma upon myelin sheath compaction and oligodendrocyte maturation. This was accompanied by a transition in mitochondrial morphology, from elongated to short and punctate, and a shift in mitochondrial movement, from dynamically repositioning within the cell to becoming largely stationary. External factors, such as anesthesia and sedation, but not glutamatergic and GABAergic neuronal activity, modulated OPC mitochondrial motility.
Next, using a DNA damage model to induce death in the oligodendrocyte lineage, I discovered that dying mature oligodendrocytes largely lose their mitochondria early after the damage, but persist for several weeks in their absence. In contrast, the other cells in the lineage die and get cleared up within hours to days. In addition, I determined that mitochondrial fission protein 1 (FIS1) levels are high in mature oligodendrocytes and may play a role in maintaining their health, as conditionally knocking out Fis1 in the oligodendrocyte lineage led to increased DNA double-strand breaks in oligodendrocytes. Lastly, aging was associated with mitochondrial changes in oligodendrocytes and their precursors, potentially contributing to oligodendrocyte degeneration and inefficient regeneration.
Overall, this work determines mitochondrial alterations linked to oligodendrocyte generation, degeneration, and aging for the first time in the intact brain. In addition, it discovers new spatiotemporal windows and suggests molecular targets that could influence how oligodendrocyte lineage cells behave in both physiological and pathological conditions
A Virus of the Mind: The Neurological Impact of Neonatal Herpes Simplex Virus Infection
No full textThe ability of herpes simplex virus (HSV) to establish lifelong latency in sensory neurons makes it one of the most pervasive viruses worldwide. Although most HSV infections are asymptomatic or cause limited cutaneous symptoms, some give rise to serious central nervous system (CNS) manifestations. Both primary HSV infection and subsequent reactivation events can cause viral replication and spread within the brain, ultimately leading to pathologic inflammation and direct CNS damage. In addition to fulminant presentations of HSV encephalitis, subclinical HSV CNS infections have been implicated in neurodevelopmental, cognitive, and neurodegenerative impairment. To model the lifelong effects of subclinical HSV infection, we infected neonatal mice with low doses of HSV and studied lasting CNS impairment associated with infection. We found that low-dose HSV infection of neonatal mice resulted in persistent CNS infection and lasting behavioral and cognitive deficits. In an ex vivo model of infection, HSV infection of mouse embryonic hippocampal neurons led to intraneuronal accumulation of beta-amyloid, suggesting that HSV may contribute to cellular neurodegeneration pathways as well as behavioral pathology. Using mutant strains of HSV-1 and transgenic mice, we found that HSV-driven neurologic impairment is dependent on autophagy inhibition by the HSV infected cell protein (ICP)34.5 Beclin-1-binding domain (BBD) and exacerbated by expression of human apolipoprotein E e4 (ApoE4). Finally, we demonstrated how HSV viral genetics can contribute to adverse infection outcomes through an accidental discovery of a novel laboratory HSV-1 strain, strain R. Together, the data described in this thesis establishes a model for studying HSV-driven neuroimpairment, addresses a mechanism of viral damage following neonatal HSV infection, and explores both host and viral genetic factors that may confer increased susceptibility to HSV-induced neurodegeneration. Identifying the mechanisms of HSV-associated CNS damage, and the populations at highest risk for neurological morbidity, is essential for understanding the role viruses play in neurological diseases, such as Alzheimer’s Disease (AD). Through these studies, we hope to inform the development of novel treatments for HSV infection and AD and motivate continued research on the relationship between early-life viral exposures and neurodegeneration
When Reading for the Plot Goes Wrong: “Death and the Compass” (“La muerte y la brújula”) by Jorge Luis Borges (1899-1986) and “The Sunglasses Society” (《眼镜会》) by Sun Liaohong (1897-1958)
Full text linkDetective fiction was once considered the pulpy, mass-consumed genre of a newly literate class with unrefined taste and an unquenchable desire for temporary withdrawal from the chaotically modernizing urban centers of the early 20th century. It has since transcended national boundaries to become a fully potentiated sect of world literature. As it traveled the world, local additions that imitated a recognizable form were imbued with distinct locality– detective fiction became both global and local, undertaking the universal questions of morality, law, order, and modernity in juxtaposition with the domestic circumstances that complicated them. This presentation places two detective stories in comparison, “The Death and the Compass” (“La muerte y la brújula”) by J.L. Borges (1942) and “The Sunglasses Society” (“眼镜会”) By Sun Liaohong 孙了红 (1921), analyzing where they conform to and transgress generic conventions. Drawing similarities between both the short stories themselves and the sociopolitcal climates of Argentina and China in which they were written, each story is understood as a commentary on how the teleologically oriented epistemological order of detective fiction unfolds in a local context. This presentation argues that by showing a fundamental failure of the inductive reasoning traditionally championed in detective fiction, these works present the dangers of applying an a priori reasoning detached from reality to the multifaceted cultural anxieties of countries with burgeoning senses of national identity
Belowground Biomass Shifts Along a Temperate Forest Edge
No full textAnthropogenic land use change and development has caused widespread global forest fragmentation, resulting in a greater proportion of forests at or near a forest edge. Temperate forests are the most fragmented forest biome, and forests in the Northeastern U.S. are particularly fragmented due to a history of intense land use and development pressure. Nearly a quarter of these forests are now within 30 meters of a forest edge. These edge ecosystems have distinct abiotic and biotic gradients that differentiate them from forest interiors, including increased light, temperature, and exposure to wind and other disturbances, as well as decreases in humidity and soil moisture. Unlike in tropical forests, edge conditions in temperate regions have led to increased aboveground growth and biomass. Effects of edges on belowground biomass are much less understood, and current estimates of net primary productivity and carbon storage at temperate edges are largely based on aboveground observations. However, belowground systems can greatly affect ecosystem-wide biogeochemical cycling of nutrients and carbon. In order to gain a more comprehensive understanding of biomass shifts along forest edges, soil, root, and microbial samples were collected in the summer of 2024 at a recent forest clearcut site at Harvard Forest in Petersham, MA. I investigated shifts in root biomass pools across an anthropogenic forest edge, including live fine tree roots, root necromass, and herbaceous and shrub roots, as well as shifts in microbial biomass and functional group composition using PLFA analysis. I observed an increase in live fine root biomass below a soil depth of 20 cm at the forest edge, with increases specifically associated with Quercus rubra (red oak). These root biomass differences may be related to the observed drier soils that could cause root proliferation at depths with relatively more water availability. There were also more Gram-negative bacteria-associated PLFAs at the edge below a soil depth 20 cm, although no other differences in microbial biomass or functional group composition were observed. Contrary to my hypotheses, root and microbial biomass were not significantly different between the forest interior and forest clearing. These results suggest that there are species-specific shifts in fine tree root biomass along temperate forest edges, highlighting the plasticity of root systems to abiotic conditions and indicating increased potential for carbon sequestration and storage along temperate edges, particularly in oak-dominated temperate forests. Belowground biomass pools must be incorporated into future studies in order to get a comprehensive understanding of forest response to edge conditions, especially as climate change and other disturbances exacerbate conditions along the edge