University at Albany, State University of New York
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Epitaxial Quantum Dot Scintillators with Monolithic Photodetector Integration: Physics, Fabrication and Characterization of Materials and Devices
Get PDFThis dissertation discloses the physics, fabrication, and characterization of high-performance scintillator detectors based on epitaxial InAs quantum dots (QDs) in GaAs. The detector crystals grown include monolithically integrated In0.35GaAs photodetectors with Al0.92-0.6In0.03-0.35Ga0.05As metamorphic buffer layers (MBL). A device fabrication process was developed for the lithographic patterning, chemical etching, contact metallization and readout integration of materials grown by means of molecular beam epitaxy (MBE) on 3-inch GaAs (001) wafers. Low capacitance integration with readout electronics was achieved through wire bonds to custom printed circuit boards (PCBs) with commercial components.
The relationship between device geometry and response was explored through exposure to alpha particles from Americium-241, 510 nm laser scans and Monte Carlo (MC) simulations. The detector response was found to be described within a ray-optics framework which includes material characteristics and device dimensions. An accurate analytical device model was obtained through incorporation of solid and plane angle-based approaches to estimating light detection, absorption and escape.
To investigate the ability of the scintillation material to support picosecond scale timing resolution through high and fast light yield, the photodetector response to the scintillation emission was read out with low noise operational amplifier-based circuits. A simulation program with integrated circuit emphasis (SPICE) was used to evaluate readout circuit designs which were ultimately validated experimentally. The effects of modulation doping on scintillation photon yield corroborate previous measurements made with photoluminescence. Light yields exceeding 40,000 photons/MeV were observed at an overall efficiency of ~17%. Devices with ~1 GHz of bandwidth were used to achieve estimated timing resolutions as low as 30 ps. Linearity was studied via 5 calorimetry of air-attenuated alpha particles. The device model was validated and used in experimental design to minimize the contribution of internal collection efficiency gradients and discern a σ/μ upper limit of 2.6% for the intrinsic energy resolution of the scintillator
Divided by Fear: The Influence of Political Beliefs on the Perception of Extremist Groups
Get PDFActs of violent extremism and support for political violence have increased in the United States over the past decade. Previous studies have primarily focused on the differences in risk perception between White Supremacists and Islamic Extremists/Jihadists, neglecting other ideological movements. This study utilizes data from the fifth wave of the Chapman Survey of American Fears and employs ordinal logistic regression to compare the fear of seven different extremist groups and movements: Islamic Extremists/Jihadists, the Militia/Patriot Movement, White Supremacists, Extreme Environmentalists, Extreme Animal Rightists, Anti-Immigration Groups, and ANTIFA. The findings reveal notable differences across political parties (Democrats, Republicans, and Independents) and ideologies (conservatives, liberals, and moderates). The findings suggest that political ideology plays a more significant role in shaping the fear of various extremist groups than party membership. These results support social identity theory and the ideological conflict hypothesis, highlighting the essential role that political ideology and party affiliation play in identity formation. This study reveals the nuanced relationship between political ideology, party affiliation, and the perception of extremism
Adaptive Evolution Shapes the Transmissibility of West Nile Virus in New York State
No full textArthropod-borne viruses (arboviruses), which are maintained in nature in complex transmission cycles involving hematophagic invertebrates and their vertebrate hosts, are the cause of a significant and expanding global health burden. Defining arbovirus-host interactions is necessary if we are to understand the adaptive and epidemiological potential of arboviruses. The results presented with West Nile virus (WNV Flaviviridae: Orthoflavivirus), are a compilation of such studies. WNV is the most prevalent arboviral pathogen in the U.S. and the most geographically distributed arbovirus in the world. Despite the evolutionary potential of these RNA viruses, WNV and other arboviruses have experienced only limited consensus level change. This relative evolutionary stasis has been identified utilizing primarily large, national datasets, or data collected over short periods of time, that may obscure the genetic signal of adaptation, and of a prospective advantage in mosquito vectors or avian hosts that may be restricted to a small geographic range. These studies utilize molecular epidemiology in conjunction with experimental studies to characterize and evaluate the directionally selected set of mutations comprising a unique and dominant WNV genotype and its phenotypic consequences. Taken together, these studies demonstrate the adaptive potential of WNV, and the importance of the emergence of adaptive mutations to sustained endemicity of an arbovirus species
Influence of Cloud-Radiative Forcing on Tropical Cyclone Development in Moderate Vertical Wind Shear
Get PDFThis research seeks to better understand how cloud–radiative forcing (CRF) influences the structural evolution and intensity change of tropical cyclones (TCs) during the organizaional stage, with a particular focus on environments characterized by moderate vertical wind shear. While CRF has been shown to impact TC development during genesis and mature stages, its role during the transitional post-genesis phase—when TCs exhibit disorganized convection and are highly sensitive to environmental influences—remains poorly understood. Moreover, forecasting TC intensity in moderate shear environments continues to present substantial challenges, underscoring the need for focused investigation of TC development in the moderate-shear regime.
The Weather Research and Forecasting (WRF) model is used to examine how CRF influences TC development in moderate shear environments using idealized ensemble experiments with and without CRF.
For weak TCs in the organizational stage, the response to moderate vertical wind shear is indirectly modulated by CRF, particularly at the higher end of the moderate shear spectrum. Key findings reveal a bifurcation in TC structural and intensity evolution: CRF-on TCs exhibit greater resilience to shear-induced vortex tilt and undergo sustained intensification, while CRF-off TCs experience prolonged stagnation in development and ultimately reach lower peak intensities.
CRF-on TCs are marked by reduced vortex tilt, broader outer-core wind fields, and stronger secondary circulations, resulting in a more vertically aligned and dynamically robust vortex. In contrast, CRF-off TCs undergo a brief period of rapid spin-up and radius of maximum wind contraction, but this is followed by a breakdown in structural coherence due to enhanced vulnerability to shear-induced radial and downdraft ventilation. These effects delay intensification by up to 72 hours and limit TC intensity. The initial intensification in CRF-off TCs thus represents a short-lived phase, whereas CRF-on TCs achieve a more persistent spin-up, leading to broader and stronger wind fields.
Nighttime longwave radiative processes play a key role in driving these differences. In CRF-off TCs, enhanced longwave cooling promotes downdraft development via evaporative cooling and boundary-layer destabilization, resulting in stronger low-entropy air intrusion into the core that suppresses convection. Conversely, the greenhouse effect associated with CRF increases ascent, enhances core moistening in typically subsident upshear regions, and accelerates the spin-up of the tangential wind field. These findings underscore the indirect but relevant role of CRF in shaping TC structure, thermodynamic resilience, and intensity evolution under moderate vertical shear
Understanding How County Governments Strategically Plan and Strategize Technology: A Multiple Case Study in New York State
Get PDFEmbedded in the communities they serve, local governments increasingly leverage technology to modernize processes and operations to digitally transform public services and interactions with stakeholders to create and add value. Concomitantly, they must ensure that the use of technology does not threaten the rights and safety of individuals and organizations. Digital transformation requires alignment of technology with institutional, organizational, and environmental factors in addition to persistent innovations in technology, policy, and management. This balancing act hinges on governments’ capacity for strategic technology decision-making. As technology’s value propositions expand and local governments become more reliant on it, there is a growing need to strategically manage technology as a resource and investment. Such a need necessitates strategic planning and strategizing so that local governments can better plan and respond to change, navigate the complexities of digital transformation, and maximize technology’s value while minimizing its negative impacts. Previous research on local governments mostly examines technology-related strategic decision-making processes in cities and pays less attention to such decision processes in counties, which play a significant role as providers of a range of (inter)local and regional government services and programs. Given this role and the fact that counties are pervasive as there are about 3,143 of them across the country, there is a need for more insights into the internal and external factors shaping strategic decision-making processes in county governments. This dissertation addresses these gaps through multiple case studies in the unique context of New York State, where counties exercise substantial autonomy and have experienced considerable progress and challenges in digital transformation.
Through semi-structured interviews with stakeholders and a review of relevant documents and artifacts, the study identifies institutional, organizational, and environmental factors that influence technology strategic planning in New York State counties. The results of this dissertation also contribute to a better understanding of the continuous practice of strategy or strategizing as related to technology. In terms of implications, this research offers a grounded framework for policymakers, administrators, and technology professionals within the public sector tasked with navigating priorities and challenges of digital transformation in local governments
Investigation of the Binding Mechanism between the Supplemental and Tail Regions of miRNA and mRNA within Argonaute 2
Get PDFMicroRNAs (miRNA) are a class of small non-coding RNAs that play a key role in gene silencing. miRNAs form an RNA-induced silencing complex (RISC) with the argonaute 2 (AGO2) protein in order to control gene expression through silencing messenger RNAs (mRNA). The ability for a miRNA-mRNA complex to fit into AGO2 and form the RISC is based on the location and characteristics of a central bulge, but the mechanism and interactions that lead to a functional RISC remain unknown. Using available experimental data, we modeled the miR-34 and NOTCH1 duplex inside of AGO2 with only the seed region base paired. The resulting structure was then simulated in a series of all atom molecular dynamics (MD) simulations with distance restraints being applied to the base pairs after the central bulge to investigate how the supplemental and tail region of the miRNA moves from the P channel to the N channel to bind with the mRNA
Ribosome Hibernation in Mycobacterium abscessus and Its Effect on Antibiotic Resistance
Get PDFNon-tuberculosis mycobacteria (NTM) represent a diverse repertoire of species, most of which are ubiquitous in the environment. Some NTM species, such as Mycobacterium abscessus, can cause life-threatening infections in people with underlying medical conditions. The clinical incidence of such infections is on the rise, posing an emerging threat to public health. M. abscessus is characterized by intrinsic and acquired antibiotic resistance, complicating treatment strategies. Most chemotherapeutic approaches for M. abscessus infection target the bacterial ribosome, necessitating a better understanding of the physiological processes which confer this resistance. Multiple mycobacterial species respond to zinc-limiting conditions by inducing remodeling and hibernation of 70S ribosomes. Ribosome remodeling in this context refers to the replacement of zinc-binding proteins on the ribosomal surface with their paralogues. Ribosome hibernation involves binding of mycobacterial protein Y (Mpy) to the 30S subunit near the inter-subunit interface of the 70S ribosome encompassing the decoding center, thereby inactivating the ribosome in a stable state. We hypothesize that Mpy-dependent ribosome hibernation drives resistance to a clinically relevant aminoglycoside in M. abscessus, amikacin. We perform a systematic analysis of ribosome remodeling and hibernation in M. abscessus and determine the effect of ribosome hibernation on the susceptibility of M. abscessus to amikacin. Lastly, we offer new insights into the mycobacterial stringent response in a model in which Rsh surveils the amino acylation status of the tRNA during the first cycle of elongation to activate the stringent response. We note that this mechanism of Rsh activation is programmed to slow down upon induction of ribosome hibernation
Mobile Air Quality Assessment Using Public Transportation: A Community-Focused Study in the Capital Region
Get PDFThe monitoring of air quality plays a crucial role in establishment of concentrations of air pollutants over space and time in relation to human health, urban planning, and environmental conservation. This research offers a new strategy of monitoring the air quality in the Capital Region of New York State utilizing public transit buses as air quality moving sampling platforms. To assess the level of pollutants, a Capital District Transportation Authority (CDTA) bus network was used across the urban, suburban, and rural areas thus filling a research gap where public transit has most of the time been disregarded as a mobile monitoring platform.
The study was conducted in seven county’s of New York’s capital region: Schenectady, urban Troy, suburban Slingerlands and Glenmont, industrial Cohoes, rural Schodack and Cross gates Mall. Cities including Schenectady and Troy present information on pollution in congested, developed regions appreciated more for their industrial value as compared to less-urban areas such as Slingerlands and Glenmont. Cohoes, with its blend of industrial, commercial, and natural landscapes, and Schodack, a predominantly rural area, together demonstrate that both densely and sparsely populated regions can exhibit unexpected pollution trends, challenging the assumption that urban density alone drives high exposure levels. Moreover, Cross gates Mall, an area of commercial traffic density that attracted dense vehicular and pedestrian traffic, provided insights into emissions from densely travelled zones.
In order to assess the ambient air quality and pollution hotspots the study uses relatively low- cost sensors and monitors such as Observ Air, Duet Sensors, P-Trak, and Q-Trak technologies. To measure black carbon (BC), particulate matter (PM₂.₅), ultra-fine particles (UFP), carbon dioxide (CO₂) and carbon monoxide (CO) respectively. The study was conducted in the Fall 2024 and Spring 2025 to understand the seasonal variation in air quality across different routes.
In addition to the time variation, other key factors like heating emissions and increased vegetation in spring were also assessed. This temporal approach offers a better perspective of pollutant behavior and exposure within various kinds of weather and community structures.
The results of this study are comparable with other existing literature and seeks to contribute to the trends in air quality by identifying spatial and seasonal variability in the Capital Region. Therefore, by using public transportation as the mobile monitoring unit, the project argues the prospect of a real-time, cost-efficient, eco-friendly, and easily expandable air quality monitoring initiative. Therefore, the findings have important implications for public health, environmental justice, and urban and transportation planning and policies, and provide important information that could be used by various policymakers, authorities, and citizens to design specific and effective pollution reduction interventions and to enhance the environmental conditions in various urban areas
Can We See How It Works? The Interactions among Teacher, Student, and Content at a Living History Museum
Get PDFToday’s students need to be critical consumers of information. To that end, a thoughtful social studies curriculum provides students an opportunity to gain content knowledge and to practice thinking skills. However, elementary teachers, especially primary grade (K-2) teachers, often do not possess the skills and content knowledge to teach rich historical content and thinking skills. Teachers can partner with museum professionals and access museum content in this endeavor. Living history museums, immersive museums that interpret multiple buildings, trades, and heritage breed animals, hold the potential to be a strong partner for primary grade students, who are only 5-, 6- and, 7- years old.
Focusing on primary grade teachers, museum educators, and students, this qualitative, design-based, case study research sought to answer the following research questions: When a living history museum is used in primary grade social studies instruction how do the classroom teachers interact with the museum educators and students? How do the museum educators interact with the primary grade teachers and students? And, how is the Visual Thinking Strategies (VTS) protocol used during field trips to a living history museum and to what effect?
Using Hawkins (1967/1975/2003) I, Thou, It (Teacher-Student-Content) framework, I studied the interactions, questions, and responses of the museum educators, primary grade teachers, and students while visiting a living history museum in rural upstate New York that interprets a working 19th century sawmill. Findings indicate that the relationships and interactions among the primary grade teacher, museum educator, and students are complex—with the adults independently and collaboratively serving as the I, or teacher. Teachers also became learners, learners of both the museum artifacts and of primary grade students. In addition, one museum educator deployed the Visual Thinking Strategies thinking protocol. The VTS protocol allowed the interactions among the students and the content to be the primary focus of the experience, promoted student exploration, and honored the knowledge that students brought to the museum
Large Scale Machine Learning over Knowledge Graphs
No full textKnowledge graphs (KGs) have become popular across various fields, providing convenient access to web-based knowledge while storing and formalizing domain-specific information. By analyzing KGs, patterns, connections, and dependencies can be identified across different data sources, enabling the inference of new knowledge from given facts. As the use of KGs expands, the size of modern KGs has grown significantly, making them impossible to process within the main memory of a single computer. Distributed computing offers a viable solution to this challenge by leveraging the combined capabilities of multiple servers within a cluster. This thesis explores how distributed computing can be effectively utilized to perform machine learning over large knowledge graphs, with a focus on facilitating scalable analytics and accelerating downstream tasks. Specifically, this thesis addresses three core challenges: (i) how to facilitate analytics over Knowledge Graphs in Apache Spark, (ii) how to compute KG embeddings at scale, and (iii) how to accelerate and enhance a representative downstream task