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Dissertations, Theses, and Masters Projects

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Articles 121 - 150 of 1876

Full-Text Articles in Physical Sciences and Mathematics

Calculation Of Gluon Pdf In The Nucleon Using Pseudo-Pdf Formalism With Wilson Flow Technique In Lqcd, Md Tanjib Atique Khan Jan 2021

Calculation Of Gluon Pdf In The Nucleon Using Pseudo-Pdf Formalism With Wilson Flow Technique In Lqcd, Md Tanjib Atique Khan

Dissertations, Theses, and Masters Projects

A comprehensive study of the gluonic content in the nucleon from a first principles lattice quantum chromodynamics calculation is presented. The unpolarized gluonic distribution in the nucleon is calculated using the pseudo-PDF framework on the lattice. First, the spectral analyses of the low-lying states in the nucleon, as well as in the delta are performed on the lattice, identifying baryons states with hybrid characteristics, in which the gluons play a manifestly structural role, and determining a set of operators which have significant overlaps onto the ground state of the nucleon. Techniques such as distillation for smearing the quark fields, momentum …


Investigating Economic Costs Of Derelict Blue Crab Callinectes Sapidus Pots And Preferred Mitigation Solutions In The Chesapeake Bay, James Delbene Jan 2020

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 …


Composition And Bioavailability Of Effluent Dissolved Organic Nitrogen, Quinn Nicole Roberts Jan 2020

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 …


Hardware-Assisted Security Mechanisms On Arm-Based Multi-Core Processors, Shengye Wan Jan 2020

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. …


Design And Analysis Of Memory Management Techniques For Next-Generation Gpus, Haonan Wang Jan 2020

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 …


Efficacy And Unintended Outcomes Of Spatial Property Rights For Fisheries And Aquaculture Management In Chile And In Virginia, U.S.A., Jennifer Beckensteiner Jan 2020

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 …


Inorganic Carbon Chemistry In East Antarctic Coastal Polynyas, Mar C. Arroyo Jan 2020

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, …


Dietary Monitoring Through Sensing Mastication Dynamics, Shuangquan Wang Jan 2020

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 …


Competing And Cooperating Orders In The Three-Band Hubbard Model: A Comprehensive Quantum Monte Carlo And Generalized Hartree-Fock Study, Adam Chiciak Jan 2020

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 …


On Cross-Series Machine Learning Models, Xiaodan Zhu Jan 2020

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 …


Cross-Scale Simulations: An Innovative Approach To Evaluate The Impacts Of Sea-Level Rise On Tidal Marsh Habitats, Mirtha Karinna Nunez Jan 2020

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 …


Experiments And Theory On Dynamical Hamiltononian Monodromy, Matthew Perry Nerem Jan 2020

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 …


Influence Of Suspended Particle Size And Composition On Particle Image Processing, Estuarine Floc Fractal Properties, And Resulting Estuarine Light Attenuation, Kelsey Fall Jan 2020

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 …


The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability, Daniel J. Coleman Jan 2020

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 …


Recruitment Characteristics Of Juvenile Striped Bass (Morone Saxatilis) Across Recovery Periods, Year Classes, And Subestuaries Of The Chesapeake Bay, Olivia M. Phillips Jan 2020

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 …


Pinpointing Software Inefficiencies With Profiling, Shasha Wen Jan 2020

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 …


Spatial And Temporal Distribution Of Phycotoxins In Lower Chesapeake Bay: Method Development And Application, Michelle D. Onofrio Jan 2020

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 Jan 2020

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 …


Quantitative Analysis Of Ekg And Blood Pressure Waveforms, Denise Erin Mckaig Jan 2020

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 …


Understanding Performance Inefficiencies In Native And Managed Languages, Pengfei Su Jan 2020

Understanding Performance Inefficiencies In Native And Managed Languages, Pengfei Su

Dissertations, Theses, and Masters Projects

Production software packages have become increasingly complex with millions of lines of code, sophisticated control and data flow, and references to a hierarchy of external libraries. This complexity often introduces performance inefficiencies across software stacks, making it practically impossible for users to pinpoint them manually. Performance profiling tools (a.k.a. profilers) abound in the tools community to aid software developers in understanding program behavior. Classical profiling techniques focus on identifying hotspots. The hotspot analysis is indispensable; however, it can hardly diagnose whether a resource is being used in a productive manner that contributes to the overall efficiency of a program. Consequently, …


A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks Jan 2020

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 …


Deep Learning In Software Engineering, Cody Watson Jan 2020

Deep Learning In Software Engineering, Cody Watson

Dissertations, Theses, and Masters Projects

Software evolves and therefore requires an evolving field of Software Engineering. The evolution of software can be seen on an individual project level through the software life cycle, as well as on a collective level, as we study the trends and uses of software in the real world. As the needs and requirements of users change, so must software evolve to reflect those changes. This cycle is never ending and has led to continuous and rapid development of software projects. More importantly, it has put a great responsibility on software engineers, causing them to adopt practices and tools that allow …


Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina Jan 2020

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 …


Structural And Dosage Dependence Of Electron Transfer From Conjugated Polymer Nanoparticles, Jaclyn Rebstock Jan 2020

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 …


Growth Engineering And Characterization Of Vanadium Dioxide Films For Ultraviolet Detection, Jason Andrew Creeden Jan 2020

Growth Engineering And Characterization Of Vanadium Dioxide Films For Ultraviolet Detection, Jason Andrew Creeden

Dissertations, Theses, and Masters Projects

There is a need for efficient ultraviolet (UV) detectors in many fields, such as aerospace, automotive manufacturing, biology, environmental science, and defense, due to photomultiplier tubes (the currently available technology) often not meeting application constraints in weight, robustness, and power consumption. In my thesis, I demonstrate that high quality vanadium dioxide (VO2) thin films, epitaxially grown on niobium doped titanium dioxide substrates (TiO2:Nb), display a strong photoconductive response in the UV spectral range, making them promising candidates for photomultiplier-free UV photodetection. By adjusting the characteristics of the substrate and VO2 film, the samples achieve external quantum efficiency exceeding 100% (reaching …


Wearable Technology For Healthcare And Athletic Performance, Amanda Annette Watson Jan 2020

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 …


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 Jan 2020

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 …


Environmental Controls On Pteropod Ecology And Physiology Along The Western Antarctic Peninsula, Patricia Susan Thibodeau Jan 2020

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 …


Copper(I) Iodide-Based Chemical Sensor Materials In Gaseous And Aqueous Media, Matthew D. Kessler Jan 2020

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 …


Insulator To Metal Transition Dynamics Of Vanadium Dioxide Thin Films, Scott Madaras Jan 2020

Insulator To Metal Transition Dynamics Of Vanadium Dioxide Thin Films, Scott Madaras

Dissertations, Theses, and Masters Projects

Vanadium Dioxide (VO2) is a strongly correlated material which has been studied for many decades. VO2 has been proposed for uses in technologies such as optical modulators, IR modulators, optical switches and Mott memory devices. These technologies are taking advantage of VO2’s insulator to metal transition (IMT) and the corresponding changes to the optical and material properties. The insulator to metal transition in VO2 can be accessed by thermal heating, applied electric field, or ultra-fast photo induced processes. Recently, thin films of VO2 grown on Titanium Dioxide doped with Niobium (TiO2:Nb), have shown promise as a possible UV photo detector …