1983 research outputs found
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Sustainability Assessment of Large-Scale Green Hydrogen Production Systems for the Energy Transition
No full textThis research provides a framework for a broader assessment of the sustainability
of investment in large-scale hydrogen generation facilities, encompassing ultrapure water
units, electrolyzers of type PEM, AEL, or SOEC, and gas purifiers. The results should
improve the business case by understanding the level of risk and proposing mitigation
options for the most critical impacts on the sustainable development goals. The study
included mapping and quantifying the environmental and social impact of these green
hydrogen value chain components and a techno-economic review of 29 global technology
suppliers. It evaluated the sustainability of a typical corporate financial business model
with and without the effects of carbon pricing due to CO2 emissions reductions, the
impact of hydrogen leakages, depletion of fresh water, the liabilities for mining metals
for catalyzers, and fabrication of water splitting systems, among others. The individual
performance of equipment was assessed using the leverage cost of energy and LCA
methods.
The key questions of this research focused on the environmental externalities of
the ultrapure water unit and PEM electrolyzer and their role in the sustainability of large
infrastructure until 2050. Other key questions were related to the potential social and
environmental impacts on the facility's economy and their impact on the business case.
Finally, I tested a hypothesis about the main variables of the levelized cost of hydrogen to
understand the effect of direct subsidies on capex versus the cost of renewable electricity
and other value chain elements.
I performed a financial analysis of the cost of equity that is sensitive for later
analysis of levelized costs and a business model built on a spreadsheet. The factors used
for liabilities were extracted from the LCA literature review and engineering proxies for
estimating H2 leakages into the atmosphere. The forecast for 2030 and 2050 used time
series analysis and official projections from the IEA.
The research confirmed a levelized cost of hydrogen of 5.11 USD/Kg and a cost
of ultrapure water of 0.045 USD/Kg of H2, with a pivotal price of 2.3 USD/Kg to be
competitive versus fossil fuel options. The cost of electricity was the most sensitive value
in the business case, and the sensitivity analysis confirmed a potential perverse incentive
if subsidies continue in an electricity market below 20 USD/MWH. The water cost was
irrelevant for H2 production, making reverse osmosis for seawater the option with fewer
social and environmental risks. The cost of equity used in the research was 12%, which is
adequate for the level of risk from a corporate perspective. The forecast of the potential
transformation of fossil fuel consumption in OECD and non-OECD countries, the
upgrade of current blue and gray hydrogen, and the coming PtX energy products
confirmed an important role of green H2 in the following decades, replacing fossil fuel
based global energy systems.
Finally, to allow a more transparent comparison of projects and components under
an ESG approach, a spreadsheet tool was constructed to incorporate the previous findings
to understand the effect of profitability versus the impacts on sustainability. The main
output was a comprehensive framework for this category of energy system (>1MW),
which is critical for the energy transition until 2050.Extension Studie
Policy and Violence in Mexico
No full textIn 2018, drug-related homicides in Mexico increased 15% year over year, at the same that the the Movimiento Regeneracion Nacional (hereafter MORENA) party came to national power and implemented policies intended to disempower cartels. This study implements a close election regression discontinuity design (RDD) to examine the effects of a MORENA win in a close election on a number of violence-related outcomes, including homicide rates and cartel presence. In order to examine this effect, I created a novel panel data set at the municipality-year level from 2015-2020, combining the panel data set from Sobrino (2020) that contains cartel indicators, with political data and homicides rate data publicly available through the Mexican government and its various agencies. The two most important findings from this paper are first, that a MORENA win leads to a general decrease in cartel presence and cartel number, and second, that this effect is reversed if MORENA was the incumbent party, where MORENA with incumbency status leads to increased cartel presence and number of cartels. To my
knowledge, this paper is among the first that documents the effect of MORENA party policies in combatting cartelsApplied Mathematic
The Role of Vision in Single-Leg Balance
No full textIt is something that we all take for granted, but humans’ ability to balance is a complex task. Upright stance is not a stable equilibrium, and without any control from our muscles, even the smallest disturbances would cause us to fall over. In this study, I looked into how the integration of different sensory feedback mechanisms allows us to properly balance when performing tasks such as walking, jumping, or standing on one foot. Specifically, I wanted to examine the role of vision in balance, and strategies we deploy to balance without it. When we close our eyes, how does our body make up for this loss of information, if at all? In order to better understand this question, we had participants stand on one leg with their eyes open and closed, and their preferred balancing strategies for each trial were tracked. It was observed that when subjects had their eyes open, they preferred to use the ankle strategy, in which one actuates their ankle in order change their center of pressure. Without vision, the subjects incorporated the hip strategy in concert with the ankle strategy, oscillating their torso side to side in order to stabilize their center of mass. I then compared this experimental data to an inverted pendulum model in order to see if I could isolate the role of vision from other feedback, and saw that a strategy analogous to our subjects’ hip strategy was employed once the model was unable to determine its absolute height. These findings are a first step to help us understand exactly how the sensory information we receive is reflected in our behavior, and points us towards interesting questions in human sensory integration which can help better inform sensory processing disorders.Applied Mathematic
Observation of the Yamaji effect in a cuprate and FL* theory of the pseudogap
No full textPhysicsAuthor's Origina
Crypt density and recruited enhancers underlie intestinal tumour initiation
No full textOncogenic mutations that drive colorectal cancer can be present in healthy intestines for long periods without overt consequence. Mutation of Adenomatous polyposis coli (Apc), the most common initiating event in conventional adenomas, activates Wnt signalling, hence conferring fitness on mutant intestinal stem cells (ISCs). Apc mutations may occur in ISCs that arose by routine self-renewal or by dedifferentiation of their progeny. Although ISCs of these different origins are fundamentally similar, it is unclear if both generate tumours equally well in uninjured intestines. Also unknown is whether cis-regulatory elements are substantively modulated upon Wnt hyperactivation or as a feature of subsequent tumours. Here, we show in two mouse models that adenomas are not an obligatory outcome of Apc deletion in either ISC source but require proximity of mutant intestinal crypts. Reduced crypt density abrogates, and aggregation of mutant colonic crypts augments, adenoma formation. Moreover, adenoma-resident ISCs open chromatin at thousands of enhancers that are inaccessible in Apc-null ISCs not associated with adenomas. These cis-elements explain adenoma-selective gene activity and persist, with little further expansion of the repertoire, as other oncogenic mutations accumulate. Thus, cooperativity between neighbouring mutant crypts and new accessibility at specific enhancers are key steps early in intestinal tumourigenesis.Accepted Manuscrip
Teeth and Dental Development as a Peripheral Marker of Early Life Stress Exposure in Mice
No full textIntroduction: Early life stress (ELS) has been shown to have long-lasting effects on human and murine development. In humans, ELS has been shown to increase the risk of anxiety, depression, and substance abuse later on in life. In mice, ELS in the form of limited nesting and bedding material has been shown to have persistent effects on adult murine behavior, with more persistent effects observed in males. Compared to females, males show an accelerated development of fear conditioning and significant depression and anxiety-like behavior. Conversely, females show delayed sexual maturation and cognitive function; these manifestations seemingly resolve with age.
Objectives: We asked whether dental development tracks the deviations in development and allows for the use of teeth as a potential biomarker of early life adversity. We tested whether the expression of receptors that link neural development with dental development can be used as mechanistic markers of altered tooth mineralization.
Material and Methods: Eighty-seven C57BL/6J mice from ELS and control groups were sacrificed at postnatal days 12 (n=49) and 78-83 (n=38). Whole heads were fixed in 10% zinc-formalin and, after rinsing, stored in 50% ethanol. To analyze craniofacial and dental development, whole heads and mandibles were scanned at 6 μm voxel size (Scanco μCT-40). Image stacks were analyzed using ImageJ, Imaris, and Amira software. For immunohistochemistry (IHC) and immunofluorescence (IF) procedures, soft tissue was removed, and fixed mandibles were dehydrated, embedded in paraffin, and sectioned. Kallikrein-related peptidase 4 (KLK4), androgen receptor (AR), and gamma-aminobutyric acid alpha one (GABA-α1) receptor expression were evaluated. Primary antibodies used were: rabbit polyclonal anti-GABA A receptor alpha 1 antibody, rabbit monoclonal recombinant anti-androgen receptor antibody, and rabbit polyclonal anti-KLK4 receptor antibody. Secondary antibodies used for IHC and IF, respectively, were biotinylated goat anti-rabbit IgG and goat anti-rabbit Alexa Fluor 594.
For elemental maps of mature, erupted enamel and dentin, fixed mandibles were embedded in Epo-Tek 301-1 epoxy resin and polished to the sagittal midplane of the incisor. Laser ablation-inductively coupled mass spectrometry (LA-ICP-MS) analysis was performed. Semi-quantitative analyses of sodium, potassium, magnesium, phosphorous, sulfur, chloride, iron, nitrogen, and carbon normalized to calcium were performed using Iolite 4 software (Elemental Scientific, Inc.).
Results: Our μCT findings show 6.9% (p=0.01) thinner incisor enamel in adult males exposed to ELS. No significant differences in molar or incisor enamel thickness are seen in adult females. On day 12, ELS males show 59% thinner molar enamel (p.0001), and females show 49.9% (p.0001) thinner molar enamel than controls. Moreover, differences in mandibular first molar mineral density are observed between male and female ELS groups compared to controls (n=49)(p.05). To our knowledge, this is the first study to show the presence of GABA- α1 receptors on mature ameloblasts of the continuously developing adult mouse incisor. We find differences in the timing of GABA- α1 expression between ELS and controls, with a slightly accelerated expression in ELS males. We also find a more robust expression of AR in the dental epithelium of ELS and control males compared to females. Our LA-ICP-MS analyses show differences in the hardness of enamel and dentin between ELS groups and controls. However, no differences in elemental composition were observed between groups.
Conclusion: The results of this study are consistent with the overall findings of sex-dependent responses to stress and an altered pace of development. To our knowledge, this is the first study to demonstrate the connection between ELS and GABA- α1 expression in dental tissues. Ultimately, our findings support the role of dental tissues as a possible biomarker of early life adversity.Oral Biolog
Eminent demesnes – A proposal to co-habit 6,000 gardens
No full textThis thesis tackles Ireland’s national housing crisis through the redesign of the lakeside demesne of Glenade House in the Northwest of Ireland. The project subverts the inherited picturesque landscape, while blurring the boundaries of landscape and architecture through inhabiting a communal garden. Demesnes were untenanted pleasure grounds retained by the aristocratic landowning class during the English plantation of Ireland from the 17th to the 20th century. Responding to the demesnes’ legacy of land confiscation and propriety, a compulsory purchase order will be served on the 6,000 demesne parklands. These demesnes will function as a network at a local and national scale, promoting local food production, sustainable building practices, and rural recreation. By concentrating dwelling on designated ‘sub-rural’ sites, the proliferation of urban sprawl into green belts can be halted, while meeting the cultural desire to live in the countryside. In short, this project institutes a housing cooperative rooted in communal landscape practices.Department of Landscape Architectur
Frame to Foreground: Translating Documentary Landscapes in Braddock, PA
No full textThe project posits that critical photography should be adopted as a design methodology – starting from the representation of a diagnostic relationship between a subject and their setting to grasp at the ineffable affect that artists capture beautifully, and often revealing social issues, left in tension within the frame through photographic techniques. This thesis project argues the translation of critical photography into spatial elements is crucial for our understanding of place. Furthermore, this new methodology reveals the concept of defining landscape as a set of relationships between living beings.
The project is about preserving what every local in Braddock, Pennsylvania holds—a strong relationship to place. Using Frazier’s framing techniques, this thesis injects photography directly into the method of design. The project imagines a system of public landscapes that are centered in belonging, gathering, and reclaiming space. A riverfront park, a gathering pavilion, a public plaza, and a garden work as one to knit together a post-industrial steel mill town that has been disinvested for forty years.
This thesis is advised by Sara Zewde.Department of Landscape Architectur
Quantization, Sparsity, Reliability, and Their Interactions
No full textIn this thesis, we will explore and contribute to three seemingly disjoint areas of machine learning: quantization, sparsity, and reliability. While each of these areas are well-understood individually, there is very little existing literature on the interaction of these research areas. They are typically viewed as orthogonal to each other and solved independently. In this thesis, we would like to shed light on the fact that many practical systems employ elements from all three fields. Therefore, it is important to understand how they can influence and interact with each other.
This thesis makes the following three key contributions to the existing literature. First, it presents GoldenEye, a functional simulator for modeling fault injections into machine learning models. In particular, it targets models that use novel number formats to quantize or emulate to different data types. The flexible API design makes it easy to add new number formats as the area evolves. Furthermore, we propose a mathematical framework for using reliability analysis to inform quantization. Second, we present our work on EdgeBERT, an accelerator for accelerating transformer inference. EdgeBERT features both quantization and sparsity optimizations that together achieve strong speedups when profiled on true silicon. We also write compiler code that allows other transformer workloads to be compiled to EdgeBERT. Finally, we attempt to understand the problem of sequential applications of quantization and sparsity. We prove a theoretical result that shows that at the tensor-level sparsity before quantization is preferred over quantization before sparsity. However, we show that at the model level, the order is not too important, so long as the algorithms are "synergetic". Then, we propose a novel quantization-aware sparsity algorithm that consider the problem of sparsity when the weights are already quantized. Together, we believe that these contributions provide valuable insights to understanding the interactions between these distinct problems.Computer Scienc
Good, Bad, or Indifferent: Effects of Brain Stimulation for Those Affected by Autism Spectrum Disorder
No full textAutism spectrum disorder (ASD) is a neurological disorder that affects the social and behavioral abilities of those who are impacted by it. Because the disorder is not specific in who it affects (due to genetic and environmental factors), it is not easy to pinpoint the cause to apply a solution across the board. Which symptoms are displayed, and the severity in which they are experienced is a roll of the dice. From the time the term autism was first documented to have been spoken, consistent change is all we have known. Today, individuals who are on the spectrum have access to a more inclusive and accommodating experience when compared to historical accounts of those with ASD-like impairments.
Person-specific treatment plans and targeted therapies are available to increase quality of life while also managing the symptoms of ASD. While traditional methods such as treatment programs, medication, and the like have given this population relief, I think it is time for us to push the boundaries for our impaired brethren and sistren. Various forms of brain stimulation, as well as electroconvulsive therapy, currently provide alternative treatment measures that may be able to offer more than momentary relief for the individual as well as the caretaker. While the methodology was misused as a weapon in the past, I say we reclaim this restorative tool and look to give this population some life back to their years. By introducing case studies and other works, we will see how this tool can be utilized for the good of the ASD community.Extension Studie