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Articles 1 - 30 of 36
Full-Text Articles in Physical Sciences and Mathematics
Quantitative Analysis Of Ekg And Blood Pressure Waveforms, Denise Erin Mckaig
Quantitative Analysis Of Ekg And Blood Pressure Waveforms, Denise Erin Mckaig
Dissertations, Theses, and Masters Projects
In the intensive care unit (ICU) of a hospital, patients are monitored continuously and the data on those patients provide powerful diagnostic tools for the medical community. However, the patient data creates incredibly large data sets with instruments measuring multiple signals simultaneously. This work seeks to improve monitoring techniques through analysis of large data sets from former ICU patients. By knowing the outcomes of patients in the past, can we detect patterns to diagnose future patients while also reducing the amount of recorded information? This thesis first seeks to improve methods of storing infant electrocardiograms (EKGs) by reducing the full …
Competing And Cooperating Orders In The Three-Band Hubbard Model: A Comprehensive Quantum Monte Carlo And Generalized Hartree-Fock Study, Adam Chiciak
Dissertations, Theses, and Masters Projects
Significant progress has been made in studying strongly correlated electronic systems with major focus on understanding high-temperature superconductivity. At the center of these studies are the so-called cuprates, which are characterized by a quasi-2D Copper-Oxide plane in which superconductivity is believed to arise. From the theoretical point of view, the complex electronic structure of these materials makes a fully ab initio many-body computation a formidable task, so we are forced to focus on minimal models that can reproduce the physics, the most well known of which is known as the Hubbard Model, which relies on the Zhang-Rice singet notion to …
Temporal Variability In Cohesive Sediment Dynamics In A Partially Mixed Estuary, The York River Estuary, Virginia, Usa: A Numerical Study Developed From Observations, Danielle Tarpley
Dissertations, Theses, and Masters Projects
Fine-grained material such as silts and clays are the predominant sediment type in low energy systems such as micro-tidal embayments and estuaries. Due to its cohesive nature, fine sediment typically moves through marine systems as aggregated particles, or flocs, rather than as individual mineral grains. The particle's components, local hydrodynamics, and concentration influence floc size, density, and fall velocity. These, in turn, impact suspended sediment transport, which complicates predictions of the fate of sediment for water quality, contaminant distribution, and dredging purposes in these systems. This dissertation used a state-of-the-art modeling system and observations to examine the variability in sediment …
Composition And Bioavailability Of Effluent Dissolved Organic Nitrogen, Quinn Nicole Roberts
Composition And Bioavailability Of Effluent Dissolved Organic Nitrogen, Quinn Nicole Roberts
Dissertations, Theses, and Masters Projects
Cultural eutrophication, the overproduction of phytoplankton biomass in response to increased nutrient inputs directly associated with human activities, is a major threat to the health of Chesapeake Bay. Strict regulations, which require a reduction in nutrient loading from all sources, have been a key component to restoration efforts. Water reclamation facilities (WRFs), which discharge effluent containing nitrogen (N) and other nutrients into receiving waters, have implemented upgrades in an effort to comply with regulations. These improvements have decreased the concentration of highly labile dissolved inorganic N (DIN), leaving behind significant concentrations of dissolved organic N (DON) whose bioavailability, and therefore …
Cross-Scale Simulations: An Innovative Approach To Evaluate The Impacts Of Sea-Level Rise On Tidal Marsh Habitats, Mirtha Karinna Nunez
Cross-Scale Simulations: An Innovative Approach To Evaluate The Impacts Of Sea-Level Rise On Tidal Marsh Habitats, Mirtha Karinna Nunez
Dissertations, Theses, and Masters Projects
There is a universal consensus that global sea levels will rise at an increased rate from those in the recent past. Rising seas will dramatically increase the vulnerability of coastal communities and ecosystems. Tidal marshes are considered to be among the most valuable and vulnerable ecosystems in the world. The effects of sea-level rise (SLR) on tidal marshes are diverse, comprising changes in tidal amplitude and flow patterns, changes in sediment transport, shoreline erosion, changes in salinity gradients, landward migration of tidal habitats, variations in species composition, and habitat loss. There is an increasing concern over how accelerated rates of …
Recruitment Characteristics Of Juvenile Striped Bass (Morone Saxatilis) Across Recovery Periods, Year Classes, And Subestuaries Of The Chesapeake Bay, Olivia M. Phillips
Recruitment Characteristics Of Juvenile Striped Bass (Morone Saxatilis) Across Recovery Periods, Year Classes, And Subestuaries Of The Chesapeake Bay, Olivia M. Phillips
Dissertations, Theses, and Masters Projects
The Atlantic coast striped bass fisheries collapsed in the late 1970's due to recruitment overfishing and poor habitat quality. Recovery of the fisheries in 1995 resulted from protection of mature females, favorable environmental conditions, and several years of strong recruitment. Today, the striped bass stock is overfished. The purpose of this study was to examine recruitment characteristics of juvenile striped bass during the pre- and post-recovery periods through (1) a comparison of mortality and hatch-date distribution between periods, and (2) to examine growth metrics of individuals from the post-recovery year classes. Lengths and otolith-derived daily ages from juvenile striped bass …
Wearable Technology For Healthcare And Athletic Performance, Amanda Annette Watson
Wearable Technology For Healthcare And Athletic Performance, Amanda Annette Watson
Dissertations, Theses, and Masters Projects
Wearable technology research has led to advancements in healthcare and athletic performance. Devices range from one size fits all fitness trackers to custom fitted devices with tailored algorithms. Because these devices are comfortable, discrete, and pervasive in everyday life, custom solutions can be created to fit an individual's specific needs. In this dissertation, we design wearable sensors, develop features and algorithms, and create intelligent feedback systems that promote the advancement of healthcare and athletic performance. First, we present Magneto: a body mounted electromagnet-based sensing system for joint motion analysis. Joint motion analysis facilitates research into injury prevention, rehabilitation, and activity …
The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability, Daniel J. Coleman
The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability, Daniel J. Coleman
Dissertations, Theses, and Masters Projects
Coastal wetlands sequester carbon, attenuate waves and storm surge, filter out nutrients and pollutants, and act as nursery habitat for important fisheries. The value of these ecosystems is underscored by their vulnerability to climate change, especially sea level rise. To persist under the threat of rising sea level, coastal wetlands must build elevation vertically. Delivery of sediment to the marsh during tidal flooding is a key component in the ecogeomorphic feedbacks that lead to elevation gain. Despite the importance of suspended sediment to assessing coastal wetland vulnerability, many questions remain unanswered. This dissertation addresses the impact of suspended sediment concentration …
Filling In The Gaps: Applications Of Deep Learning, Satellite Imagery, And High Performance Computing For The Estimation And Distribution Of Geospatial Data, Seth Goodman
Dissertations, Theses, and Masters Projects
Many regions around the world suffer from a lack of authoritatively-collected data on factors critical to understanding human well-being. This challenges our ability to understand the progress society is making towards reducing poverty, improving lifespans, or otherwise improving livelihoods. A growing body of research is exploring how deep learning algorithms can be used to produce novel estimates of sparse development data, and how access to such data can impact development efforts. This dissertation contributes to this literature in three parts. First, using Landsat 8 satellite imagery and data from the Armed Conflict Location & Event Data Project, convolutional neural networks …
Copper(I) Iodide-Based Chemical Sensor Materials In Gaseous And Aqueous Media, Matthew D. Kessler
Copper(I) Iodide-Based Chemical Sensor Materials In Gaseous And Aqueous Media, Matthew D. Kessler
Dissertations, Theses, and Masters Projects
Chemical detection is an area of great importance in the shift to more green approaches to industry. Some of the chemical species produced by assorted industries can be harmful, long lived, and challenging to differentiate. Copper(I) iodide (CuI) is a material that readily forms complexes of multiple colors, both under visible and ultraviolet (UV) light. The process of CuI reacting with dimethyl sulfide vapor to produce a color change (vapochromism) has been analyzed to propose mechanistic information about the process. Using the information obtained, a series of potential sensor materials were developed with CuI as the base. The complexes were …
Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina
Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina
Dissertations, Theses, and Masters Projects
In this thesis we investigate the phenomenology of beyond the Standard Model scenarios with extra scalar fields. A review and motivation of extended electroweak symmetry breaking is presented. Then we address observational evidence of new physics such as possible lepton flavor violating processes and the relic abundance of dark matter by implementing models with three Higgs doublets. The complementarity between theoretical restrictions and experimental bounds on some of the predicted signals is leveraged to sharpen the allowed parameter space. After that we study embeddings of two-Higgs doublets into the Randall-Sundrum model with emphasis on the scalar fluctuations of the metric …
Reducing Avian Collisions With Human-Made Structures: A Sensory Ecology Approach To Open-Air Settings, Timothy James Boycott
Reducing Avian Collisions With Human-Made Structures: A Sensory Ecology Approach To Open-Air Settings, Timothy James Boycott
Dissertations, Theses, and Masters Projects
Billions of birds fatally collide with human-made structures each year. These mortalities have impacts on species of conservation concern and potentially on avian populations as a whole. This source of human-wildlife conflict also places economic and operational constraints on various human industries. Furthermore, with continued increases in urbanization, the rate and extent of collisions continues to increase. Efforts to reduce collisions have largely centered on making structures more visible to birds but have been met with limited success. Currently, there is a call for solutions to be tailored to both the environmental context of hazardous structures and to the sensory …
Impacts Of Fertilization On Salt Marsh Resilience: Altered By Location-Specific Drivers, Kenneth Michael Czapla
Impacts Of Fertilization On Salt Marsh Resilience: Altered By Location-Specific Drivers, Kenneth Michael Czapla
Dissertations, Theses, and Masters Projects
Salt marshes provide valuable ecosystem services to human society, but are currently under threat from accelerating sea level rise and nutrient enrichment. Carbon (C) and mineral accumulation allow salt marshes to maintain elevation above sea level and survive. Anthropogenic nitrogen (N) loading is increasing in many salt marshes, causing negative impacts on marsh resilience such as increased decomposition and decreased below-ground production. However, increasing N may also have simultaneous positive effects such as increased primary production and above-ground biomass, surface sediment accretion, and denitrification rates, which remove excess N from coastal waters. Many studies have been conducted to determine the …
Investigating Economic Costs Of Derelict Blue Crab Callinectes Sapidus Pots And Preferred Mitigation Solutions In The Chesapeake Bay, James Delbene
Investigating Economic Costs Of Derelict Blue Crab Callinectes Sapidus Pots And Preferred Mitigation Solutions In The Chesapeake Bay, James Delbene
Dissertations, Theses, and Masters Projects
Derelict fishing gear, particularly pots or traps, occupy waters worldwide and cause negative ecological and economic impacts. Derelict pots persist throughout Chesapeake Bay, the largest estuary in the U.S., that supports a valuable commercial fishery for the blue crab Callinectes sapidus. Chesapeake Bay is responsible for 30-40% of U.S. commercial blue crab harvests. Yet, few studies have quantified the impacts of derelict pots on harvest or the perceptions of commercial fishers on derelict pot mitigation activities in this predominantly pot fishery. This thesis examined the impacts of derelict pots on harvest in a field experiment and worked with commercial fishers …
Influence Of Suspended Particle Size And Composition On Particle Image Processing, Estuarine Floc Fractal Properties, And Resulting Estuarine Light Attenuation, Kelsey Fall
Dissertations, Theses, and Masters Projects
Understanding the nature of suspended particles is crucial to explaining water clarity issues in many estuaries, including the Chesapeake Bay and its tidal tributaries. Typical near surface estuarine particles are not individual sediment grains, but rather are clusters of inorganic and organic components known as flocs. Because of their fragile nature, flocs are challenging to observe in-situ, so their influence on the optical properties of the system are not well-known. This dissertation used a combination of state-of-the-art optical instrumentation, including laser scattering and transmissometry, a high-definition particle imaging camera system (PICS), and irradiance meters, along with supporting laboratory analysis techniques …
Efficacy And Unintended Outcomes Of Spatial Property Rights For Fisheries And Aquaculture Management In Chile And In Virginia, U.S.A., Jennifer Beckensteiner
Efficacy And Unintended Outcomes Of Spatial Property Rights For Fisheries And Aquaculture Management In Chile And In Virginia, U.S.A., Jennifer Beckensteiner
Dissertations, Theses, and Masters Projects
Marine spatial property rights reduce many common pool externalities that plague wild capture fisheries and incentivize productive use for aquaculture. Specifically, Territorial Use Rights for Fisheries (TURFs) are a management tool whereby individuals or groups are granted exclusive access to harvest resources within an area, and are the prevailing management of coastal fisheries in Chile. Additionally, secured spatial property rights appear inherently obligatory for aquaculture development; i.e., private leases in Virginia, where submerged grounds granted to an individual or a company for oyster production are considered a form of TURF. Although the number and extent of spatially managed areas are …
Pinpointing Software Inefficiencies With Profiling, Shasha Wen
Pinpointing Software Inefficiencies With Profiling, Shasha Wen
Dissertations, Theses, and Masters Projects
Complex codebases with several layers of abstractions have abundant inefficiencies that affect the performance. These inefficiencies arise due to various causes such as developers' inattention to performance, inappropriate choice of algorithms and inefficient code generation among others. To eliminate the redundancies, lots of work has been done during the compiling phase. However, not all redundancies can be easily detected or eliminated with compiler optimization passes due to aliasing, limited optimization scopes, and insensitivity to input and execution contexts act as severe deterrents to static program analysis. There are also profiling tools which can reveal how resources are used. However, they …
Inorganic Carbon Chemistry In East Antarctic Coastal Polynyas, Mar C. Arroyo
Inorganic Carbon Chemistry In East Antarctic Coastal Polynyas, Mar C. Arroyo
Dissertations, Theses, and Masters Projects
Polynyas are large areas of open water or reduced sea ice coverage that persistently form in polar environments and often experience enhanced rates of physical, chemical, and biological processes that impact ocean dynamics on local to global scales. Polynyas that form adjacent to the coast, known as coastal polynyas, play an important role in the global carbon cycle by regulating the exchange of CO2 between the ocean and atmosphere in the high latitudes. Because of their importance to the global carbon cycle, there is a particular interest to better characterize CO2 system processes in Antarctic coastal polynyas. In this study, …
Spatial And Temporal Distribution Of Phycotoxins In Lower Chesapeake Bay: Method Development And Application, Michelle D. Onofrio
Spatial And Temporal Distribution Of Phycotoxins In Lower Chesapeake Bay: Method Development And Application, Michelle D. Onofrio
Dissertations, Theses, and Masters Projects
Harmful algae can illicit adverse effects on aquatic and human health through various mechanisms, including through the production of bioactive compounds called phycotoxins. In the Chesapeake Bay, the largest estuary in the United States, little information was known about the distribution of phycotoxins, even though this region is known to harbor 37+ different species of harmful algae. Due to the presence of multiple species that can produce distinct groups of phycotoxins, a multi-toxin approach was taken to study this region. Two methods for the quantification of 13 phycotoxins (microcystin-RR, -LR, YR, azaspiracid-1, -2, karlotoxin 3, goniodomin A, yessotoxin, brevetoxin-2, pectenotoxin-2, …
Motion Sensors-Based Human Behavior Recognition And Analysis, Hongyang Zhao
Motion Sensors-Based Human Behavior Recognition And Analysis, Hongyang Zhao
Dissertations, Theses, and Masters Projects
Human behavior recognition and analysis have been considered as a core technology that can facilitate a variety of applications. However, accurate detection and recognition of human behavior is still a big challenge that attracts a lot of research efforts. Among all the research works, motion sensors-based human behavior recognition is promising as it is low cost, low power, and easy to carry. In this dissertation, we use motion sensors to study human behaviors. First, we present Ultigesture (UG) wristband, a hardware platform for detecting and analyzing human behavior. The hardware platform integrates an accelerometer, gyroscope, and compass sensor, providing a …
Environmental Controls On Pteropod Ecology And Physiology Along The Western Antarctic Peninsula, Patricia Susan Thibodeau
Environmental Controls On Pteropod Ecology And Physiology Along The Western Antarctic Peninsula, Patricia Susan Thibodeau
Dissertations, Theses, and Masters Projects
Pteropods (pelagic snails) are ubiquitous zooplankton in the Southern Ocean and abundant along the Western Antarctic Peninsula (WAP), one of the most rapidly warming regions on the planet. They are important prey for higher trophic levels, grazers of phytoplankton, and contribute to particulate organic and inorganic carbon export. Pteropods are heralded as bioindicators of ecosystem health due to the vulnerability of their aragonitic shells under ocean acidification conditions, which could greatly affect their abundances in the future. Despite their importance within Antarctic food webs, few studies have analyzed the effects of climate change on pteropod physiology and biogeography in the …
Design And Analysis Of Memory Management Techniques For Next-Generation Gpus, Haonan Wang
Design And Analysis Of Memory Management Techniques For Next-Generation Gpus, Haonan Wang
Dissertations, Theses, and Masters Projects
Graphics Processing Unit (GPU)-based architectures have become the default accelerator choice for a large number of data-parallel applications because they are able to provide high compute throughput at a competitive power budget. Unlike CPUs which typically have limited multi-threading capability, GPUs execute large numbers of threads concurrently to achieve high thread-level parallelism (TLP). While the computation of each thread requires its corresponding data to be loaded from or stored to the memory, the key to supporting the high TLP of GPUs lies in the high bandwidth provided by the GPU memory system. However, with the continuous scaling of GPUs, the …
Experiments And Theory On Dynamical Hamiltononian Monodromy, Matthew Perry Nerem
Experiments And Theory On Dynamical Hamiltononian Monodromy, Matthew Perry Nerem
Dissertations, Theses, and Masters Projects
In classical mechanics, one of the advanced topics is the study of action and angle variables. These variables are quite abstract, but very powerful tools for describing classical motion. If a system has a full set of conservation laws, and if the motion of the system is bounded, then the motion can be described as flow on a torus. Action variables are functions of the conservation laws that identify the torus on which the motion lies, while angle variables tell the location of the system on that torus. In certain cases, the functional relationship between the conservation laws and the …
Hardware-Assisted Security Mechanisms On Arm-Based Multi-Core Processors, Shengye Wan
Hardware-Assisted Security Mechanisms On Arm-Based Multi-Core Processors, Shengye Wan
Dissertations, Theses, and Masters Projects
During the last decade, Trusted Execution Environment (TEE) provided by ARM TrustZone had become one of the most popular techniques to build security on mobile devices. On a TrustZone-enabled system, the software can execute in either Secure World (trusted) and Normal World (untrusted). Meanwhile, along with the expeditious development of TrustZone technology, the security of TEE is also challenged by dealing with more and more on-board hardware and in-TEE applications. In this dissertation, we explicitly study the security of ARM TrustZone technology with the latest ARM architecture in three aspects. First, we study the security of the TrustZone-assisted asynchronous introspection. …
Structural And Dosage Dependence Of Electron Transfer From Conjugated Polymer Nanoparticles, Jaclyn Rebstock
Structural And Dosage Dependence Of Electron Transfer From Conjugated Polymer Nanoparticles, Jaclyn Rebstock
Dissertations, Theses, and Masters Projects
Conjugated polymer nanoparticles (CPNs or Pdots) have become popular fluorophores for a variety of fluorescence imaging applications due to their brightness, photostability, and aqueous compatibility. Recently, their ability to generate charged species has begun to be exploited in applications ranging from photocatalysis to photovoltaic cells. Upon excitation, CPNs can eject an electron via photoinduced electron transfer (PET) to oxygen or other acceptors. The competition between fluorescence and PET is undesirable in redox-based applications. However, CPNs are capable of the simultaneous generation and detection of reactive oxygen species, expanding their use in photodynamic therapy (PDT). We seek to determine the dependence …
Exploring Heterogeneous Architectures With Tools And Applications, Du Shen
Exploring Heterogeneous Architectures With Tools And Applications, Du Shen
Dissertations, Theses, and Masters Projects
Heterogeneous architectures have become popular due to programming flexibility and energy efficiency. Heterogeneous architectures include GPU accelerators, and memory subsystems consisting fast and slow components. Achieving high performance for programs running on heterogeneous architectures requires sophisticated tools and applications. They either lack hardware support for fast memory component, or provide complex programming model, which puts extra burdens on compilers and programmers. However, existing tools either rely on simulators or lack support across different GPU architectures, runtime or driver versions. Thus, they only provide insufficient insights. In the first project, we develop DataPlacer, a profiling tool to provide guidance for data …
Dietary Monitoring Through Sensing Mastication Dynamics, Shuangquan Wang
Dietary Monitoring Through Sensing Mastication Dynamics, Shuangquan Wang
Dissertations, Theses, and Masters Projects
Unhealthy dietary habits (such as eating disorders, eating too fast, excessive energy intake, and chewing side preference) are major causes of some chronic diseases, including obesity, heart disease, digestive system disease, and diabetes. Dietary monitoring is necessary and important for patients to change their unhealthy diet and eating habits. However, the existing monitoring methods are either intrusive or not accurate enough. In this dissertation, we present our efforts to use wearable motion sensors to sense mastication dynamics for continuous dietary monitoring. First, we study how to detect a subject's eating activity and count the number of chews. We observe that …
Unravelling The Aggregation Of Eosin Y Photosensitisers For Solar Energy Conversion, Huw Richards
Unravelling The Aggregation Of Eosin Y Photosensitisers For Solar Energy Conversion, Huw Richards
Dissertations, Theses, and Masters Projects
The impact of molecular aggregation on the photophysics of eosin y adsorbed to TiO2 was investigated using diffuse reflectance spectroscopy, steady-state fluorescence and time correlated single photon counting (TCSPC) measurements. Deconvolution of the diffuse reflectance spectra of eosin y on TiO2 revealed the formation of H-aggregates, with the extent of H-aggregation increasing with increasing dye-loading concentration. The resultant bathochromic shift from the monomer diffuse reflectance maximum is due to Charge-transfermediated H-aggregates The fluorescent maximum also shifts with increasing dye loading concentration starting at 537.5 nm at a dye loading concentration of 7.5x10-7 M and shifting to 585 …
A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks
A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks
Dissertations, Theses, and Masters Projects
Upon cooling past a critical temperature Tc = 340 K Vanadium dioxide (VO2) exhibits a metal-insulator transition (MIT) from a metallic rutile R to an insulating monoclinic M1 phase. Other insulating phases, a monoclinic M2 and triclinic T, have been identifed and are accessible via strain or doping. Despite decades of research, the nature of the VO2 MIT is still not fully understood. In this work we present ab-initio hybrid density functional theory (DFT) calculations on the insulating phases, compare the results to experimental measurements and discuss their implications on our understanding of the VO2 MIT. Recent measurements on M1 …
On Cross-Series Machine Learning Models, Xiaodan Zhu
On Cross-Series Machine Learning Models, Xiaodan Zhu
Dissertations, Theses, and Masters Projects
Sparse high dimensional time series are common in industry, such as in supply chain demand and retail sales. Accurate and reliable forecasting of high dimensional time series is essential for supply chain planning and business management. In practical applications, sparse high dimensional time series prediction faces three challenges: (1) simple models cannot capture complex patterns, (2) insufficient data prevents us from pursuing more advanced models, and (3) time series in the same dataset may have widely different properties. These challenges prevent the currently prevalent models and theoretically successful advanced models (e.g., neural networks) from working in actual use. We focus …