Dartmouth Institute for Health Policy and Clinical Practice
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Uncovering of the Hills
No full textI think stories and myths are always created from kernels of truth. In this story I create a (very fictional) mythology and setting by loosely drawing from my experiences growing up in southern India. This mythology and setting form the backdrop for my middle grade, fantasy story, Uncovering of the Hills.
My story follows Ralen, a twelve year old boy on his summer vacation as he discovers that the magical people from his childhood bedtime story are real when he accidentally meets one of them, Zaya. Soon, things start going wrong in Zaya’s world in ways that are suspiciously similar to Ralen’s storybook – a storybook that just so happens to be missing a few pages. Without the whole story to help separate fact from fiction, Ralen is faced with the challenge of figuring out how to help Zaya bring normalcy back to her world.
My intention with this story was to capture the sense of discovery that comes with growing up and learning that the world encompasses much more than initially imagined. While doing so, my aim was also to create an entertaining, well told middle grade story
Horizontal Infiltration of Water through Porous Snow as a Gravity Current
Full text linkOn the surface of the Greenland ice sheet or around the margins of the Antarctic ice shelf, water infiltrates porous ice. It is important to understand this infiltration process since water populating the pore space of ice directly impacts the density, porosity, and wetness of ice. These properties influence the mechanics and tensile strength of ice, as greater amounts of infiltration result in faster or more widespread deformation events, which may lead to adverse climatic effects such as sea level rise and ocean current disruption. While studies have considered the thermodynamics and fluid mechanics of water vertically percolating through snow under gravity, here we consider the horizontal spreading of water with freezing under gravity. In this study, we devise a one-dimensional depth-integrated model for water horizontally infiltrating porous ice via gravity current as a Darcy flow from a source of constant depth. We first analyze the infiltration process in the absence of phase change and find that the source-driven infiltration behaves self-similarly. We then capture the infiltration process subject to freezing with an analytical relationship between the source porosity and the time over which the pores at the source are frozen shut. Once the source is frozen shut, residual infiltration in the snowpack as a wetting front becomes weaker and a freezing front develops from the source. Under these freezing dynamics, we bound the region of liquid water by using the similarity solution to locate the wetting front and approximate the freezing front evolution. We then discuss methods to validate and apply the model through experiments and field observations. We construct a regime diagram to predict breakthrough potential given snowpack dimensions, ice temperature scale, and initial source porosity. We also discuss methods to extend the model theoretically to icy satellites and warm water sources
Burning Solitudes: Mountain Storytelling in the Age of Social Media Reproduction
Full text linkA deep exploration into the contradictions of recording mountain experiences while having them
The Wild Winds of Fortune: Encounters After Falling on a Gentle Acadia Path
Full text linkOn a familiar and well traveled path, a hiker learns how easily one can fall and what happens when people stop to help
PROTEOMIC APPROACHES TO INVESTIGATE PP2A-B55 SUBSTRATES AND CELLULAR FUNCTION
Full text linkCell division is controlled in large part by reversible protein phosphorylation. The phosphorylation state of proteins during mitosis and other phases of the cell cycle represents a careful balance of activity between kinases and opposing phosphatases. The phosphoprotein phosphatase (PPP) family is responsible for the majority of serine and threonine dephosphorylation. Members of the PPP family are composed of a catalytic subunit paired with a regulatory subunit that targets them towards specific substrates.
The most abundant PPP, PPP2A, paired with its regulatory B55 subunit, is thought to be the phosphatase responsible for the dephosphorylation of substrates during mitotic exit. Despite this important role, few tools exist to specifically examine its function in live cells. To address this need, we developed an auxin-inducible degron system to selectively deplete B55 from live cells. We demonstrated that this resulted in an acceleration of mitotic entry and a delay in mitotic exit. We used phosphoproteomics to identify substrates targeted by PP2A-B55 during mitotic exit. We also showed evidence that the abundance of the competitive inhibitor-substrate ARPP19 that blocks PP2A-B55 activity during mitotic entry is regulated in a PP2A-B55-dependent manner. Our results suggest that degradation of unbound, phosphorylated ARPP19 limits the pool of functional PP2A-B55 inhibitors, ensuring rapid PP2A-B55 reactivation at anaphase onset.
The mechanism by which PP2A-B55 identifies its substrates is another active topic of investigation in phosphatase biology. Several PPPs have been shown to bind their substrates through short linear motifs (SLiMs). A SLiM was proposed for PP2A-B55 but was only validated for a limited number of substrates. To further refine the SLiM definition and to identify more examples of functional SLiMs, we designed a peptide array containing PP2A-B55 SLiMs mined from the human proteome and measured purified PP2A-B55 binding to them. We identified a preference for motifs that include an aromatic residue, as well as a preference for motifs with a basic charge. Our results also support findings that PP2A-B55 prefers to bind folded short helical motifs (SHelMs). Finally, we discovered a novel B55-binding motif on c-Jun and showed that it is both sufficient and necessary to recruit PP2A-B55 in cells
The Threadbare Saint
No full textThere are roughly 280,000 migrant domestic workers living in Singapore. Many of them come from the Philippines, Myanmar, and Indonesia to work as live-in maids. About 20% of households in Singapore employ domestic workers to assist in household chores and to help care for children and the elderly. Their work is multi-faceted: they are the cooks, the dishwashers, the car-washers, the baby-sitters, the pet groomers, and the laundrymen of many Singaporean households. They play a central role in the domestic lives of thousands of families in Singapore and are undoubtedly a part of the country’s social fabric; nevertheless, they have largely been overlooked by the international community. This was the central impetus behind the “The Threadbare Saint,” a story which casts a light on an unrepresented demographic in Singapore. This novella is centered around a Filipino maid named Judith who works for a German expatriate family in Singapore. Set in 2005, this piece of fiction attempts to detail the sacrifice that domestic workers make, leaving their homes and loved ones behind to make a better living for themselves. Along the way, readers will meet a cast of characters who represent the diverse and multi-ethnic population of Singapore
Enhanced Particle Interactions in Highly Curved Spacetime
Full text linkCompact objects, such as black holes and neutron stars, are known to be surrounded by dense clouds of particles, including but not limited to photons, various plasmas, and potentially dark matter and gravitons. These environments are of immense research interest, not only for the purpose of understanding the compact objects they surround, but also in the search to identify new particles, especially dark matter. However, certain particle physics calculations are well developed in flat spacetime but intractable in curved spacetime. In this thesis, I present a formalism by which some of these calculations may be made tractable within a perturbative series. The formalism works by constructing small patches of locally flat spacetime, through which a particle travels; as a particle goes from one patch to another, the effective Lagrangian receives corrections for each patch. In this way we are able to construct comparators, analogous to a Wilson line, that transport the physics from one patch to another. These corrections can result in the enhancement of higher-dimensional, Planck-suppressed operators, enabling us to probe new physics.
This thesis also explores another topic in the area of particle behavior around a compact object, namely that of axion lasers produced by superradiance. Superradiance, a phenomenon through which energy and angular momentum may be extracted from a rotating black hole, can generate dense clouds of axions, which can then decay into photons; the number of photons produced by this decay can potentially stimulate further decay, creating a laser. This laser is powerful enough that the Schwinger effect may become significant, producing an electron-positron plasma, which has the effect of slowing axion decay by imparting photons with an effective mass. In a simplified model consisting of a rotating primordial black hole devoid of any preexisting plasma, we find, depending on the system’s parameters, that the equilibrium state of this laser may be mildly enhanced, or it may become unable to reach equilibrium, with the axion cloud continuing to grow superradiantly
SubZero Systems Hyperlocal Weather Monitoring and Alert System
No full textAccurate, hyperlocal weather data is critical for effective winter weather management. However, the Dartmouth campus’s current solutions often lack the precision for optimal ice treatment. This results in excessive and uneven salting practices, leading to increased worker and student injuries, financial and laborious burdens, and environmental damage caused by runoff. To tackle these challenges, our team has developed a comprehensive system. The system integrates hyperlocal weather station data, a peer-reviewed ice prevention optimization formula, and a machine learning model to generate intuitive salt usage recommendations and precise ice formation forecasts. The deliverables include an integrated system featuring functional weather data collection and storage, an ice formation prediction model pipeline, an algorithm for ice treatment recommendations, and a framework for future weather management applications. We aim to improve ice treatment outcomes, reduce financial and environmental impacts, and provide a foundation for future weather-related innovations at Dartmouth. Throughout the project, we have followed an iterative process of planning, developing, gathering user feedback, and problem-solving, improving our product’s scientific reliability and ease of use. The future scope for this project may include using the hyperlocal weather data pipeline to monitor heat stroke risks in collaboration with the Environmental Health and Safety Department, validating the ice formation prediction model through field testing, and improving user interaction through partnership with Dartmouth Facilities Operations and Management
Osteophone to Detect Fracture in the Field
No full textWhen assessing long bone fractures, X-ray is the state-of-the-art solution. However, its inaccessibility due to cost and distance poses a barrier to nearly half of the global population, and this lack of access inhibits prehospital triage and assessment. Currently, there are no affordable, portable options that can not only rule out— but also detect the presence of— fracture. We are developing a device that implements the principles of sound wave attenuation that underlie other state-of-the-art alternatives to X-ray, such as the clinician administered tuning fork and stethoscope method, but with improved accuracy and objectivity. This approach uses a microcontroller to process sound signals generated at one end of the long bone’s prominences by a transducer and received on the other end by a receiver. The signal is filtered and amplified for collection and processing; the magnitude and frequency data are then displayed to the user for interpretation of signal attenuation. Our device is intended to provide a vital sign-like output that can be interpreted by the user, rather than a trained technician, to help determine a treatment plan. As the device is intended for prehospital scenarios, ease of use, stable operation, and consistent readings are important, even in adverse conditions. To simultaneously address one of the most common types of fractures and prove the concept, the current device is designed for the tibia, the larger bone of the lower leg