Physics Commons^™

Remotely Sensed Assessment Of The Preferred Habitat Of Alexandrium Catenella In The Gulf Of Maine And The Bay Of Fundy, Andre F. Bucci

Electronic Theses and Dissertations

Harmful Algal Blooms (HABs) of the toxic dinoflagellate Alexandrium catenella are an annually recurring problem in the Gulf of Maine (GoM), resulting in risks to human health and substantial economic losses due to shellfish harvesting closures. The monitoring approaches in the region are restricted to real-time identification of the HABs events, when they are clearly underway and already causing deleterious effects to the environment. To fully function as an early warning system rather than an immediate response, monitoring strategies need to be focused on environmental conditions preceding A. catenella HABs. However, the current understanding of the preferred habitat for A. …

Measurement Of Airborne Radionuclides And Their Relation To Weather Patterns At Orono, Me, James W. Deaton

Electronic Theses and Dissertations

7Be and 210Pb activities were measured in air sampling filters collected at The University of Maine campus from 2014 to 2019. The activities of 7Be were in the range of 1.178-98.8 Bq, with an average value of 32.13 Bq. The activities of 210Pb were in the range of 0.091 to 13.64 Bq, and an average value of 3.029 Bq. The distributions of activity for both radionuclides are lognormal. Both 7Be and 210Pb show seasonal variation with maximum values in the summer and minimum values in the fall, and the 7Be/210Pb ratio shows a clear seasonal variation with maxima in the …

A Computational Model Of The Line-1 Retrotransposon Life Cycle And Visualization Of Metabolic Networks In 3-Dimensions., Michael D. Martin

Electronic Theses and Dissertations

Computational modeling of metabolic reactions and cellular systems is evolving as a tool for quantitative prediction of metabolic parameters and reaction pathway analysis. In this work, the basics of computational cell biology are presented as well as a summary of physical processes within the cell, and the algorithmic methods used to find time dependent solutions. Protein-protein and enzyme-substrate interactions are mathematically represented via mass action kinetics to construct sets of linear differential equations that describe reaction rates and formation of protein complexes. Using mass action methods, examples of reaction networks and their solutions are presented within the Virtual Cell simulation …

Search For A Dark Leptophilic Scalar Produced In Association With Taupair In Electron-Positron Annihilation At Center-Of-Mass Energies Near 10.58 Gev., Diptaparna Biswas

Electronic Theses and Dissertations

Dark matter is believed to be a form of matter which seemingly accounts for approximately 85% of the matter in the universe and about 27% of its total mass–energy density. It doesn't participate in electromagnetic interaction, i.e. doesn't interact with light. Consequently, we cannot see it using optical or radio telescope and hence the name dark matter. However, it participates in gravitational interaction, and we hypothesize its existence based on a variety of astrophysical observations, including gravitational effects, that cannot be explained by the accepted theories of gravity unless we account for more matter than can be perceived through electromagnetic …

Turbulent Transport Of Dissolved Oxygen In Natural Channels, Alanna Bachtlin

Electronic Theses and Dissertations

The transport and mixing of dissolved oxygen (DO) is important to replenish the oxygen depleted by natural processes; gas transfer in general has implications for ecosystem metabolism and greenhouse gas transfer. Currently, reaeration coefficients can be found through gas tracer methods, which estimates one-way gas transfer. For this project, a net oxygen consumption rate, , was developed using the similarity equations, which provides a value from DO and velocity profiles specific to a stream site. Additionally, three models to calculate friction velocity, which is required for oxygen consumption rate, were compared. Reynolds stresses, mathematically developed in the Reynolds-Averaged Navier-Stokes Equations, …

The Impact Of Sea-Level Rise In Numerically Modeled Landfalling Hurricanes: Katrina And The Gulf Coast., Serenity Nadirah Mercuri

Electronic Theses and Dissertations

With climate change, landfalling hurricanes become an increasing threat to coastal regions. However, the interactions between the coastal landscape and landfalling hurricanes are often overlooked when addressing sea-level rise outside of inundation and independent of sea surface temperature. This study analyzed the potential impacts regarding structure and intensity as a result of sea-level rise in the Gulf of Mexico using the WRF-ARW numerical model coupled with a 1D ocean model. Analysis showed that 10 m windspeed from landfall forward was higher in modified coastlines, and minimum sea-level pressure post-landfall was consistently lower for modified runs where storms maintain a higher …

Calculated Charge State Distributions And Anisotropies Following The Β-Decay Of 6he, Eva E. Sculhoff

Electronic Theses and Dissertations

According to the standard model the beta-decay of 6He is a pure Gamow-Teller transition. The aim of this thesis is to provide theoretical support in the search for new physics beyond the standard model by examining the angular distribution of beta particles following decay. The simple structure of 6He, along with its ability to under go beta-decay into 6Li+ makes it an ideal candidate for studying the weak force. Due to the sudden increase in nuclear charge from Z = 2 to Z = 3, and the recoil momentum of the daughter nucleus resulting from the emitted leptons, this decay …

Quantitative Magnetic Resonance Imaging Methodology Development, Layale Bazzi

Electronic Theses and Dissertations

Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging modality that provides excellent soft tissue contrast and resolution. Objects with high magnetic susceptibility distort the magnetic field, leading to severe artifacts in conventional MRI. It is very challenging to image around metal implants. Novel strategies may exploit the field distortion for spatial encoding. The magnetic field map is required in the development of these methods. A robust field map can also be employed to quantify high susceptibility particles that play a major role in cell tracking studies and hyperthermic treatment of cancers.

Pure phase encoding (PPE) techniques with short encoding …

Inhibitors Of Alpha-Synuclein Aggregation, Jemil Ahmed

Electronic Theses and Dissertations

Alpha-Synuclein (αS) – a neuronal, disordered, presynaptic protein – aggregates into amyloid fibrils and accumulates in the substantia nigra pars compacta of Parkinson's Disease (PD) patients. The aggregation and accumulation of αS amyloid fibrils leads to death of dopaminergic neurons; a hallmark of PD. Although it’s not clear why αS aggregates, prior studies have found that intrastriatal injection of fibril alone is sufficient to cause PD pathology in mouse and non-human primates models. These observations implicate αS as a therapeutic target against PD.

Unfortunately, there are three caveats when attempting to target αS. First, αS is a neuronal protein expressed …

Femtosecond Pulse Compression Via Self-Phase Modulation In 1-Decanol, Jacob A. Stephen

Electronic Theses and Dissertations

Ultrafast science is a branch of photonics with far reaching applications in and outside the realm of physics. Ultrashort laser pulses on the order of femtoseconds (1 fs = 1 × 10−15 s) are widely used for ultrafast science. Many lasers can produce pulses on the order of 100 fs, with state of the art, high end lasers being capable of producing pulses around 30 fs. However, many experiments require pulses around 10 fs or shorter. Femtosecond pulses are typically generated using spectral broadening via self-phase modulation, followed by dispersion compensation. The most common spectral broadening technique exploits the nonlinear …

Simple Measurement For Ultrafast Field Reconstruction, Chathurangani Jayalath Arachchige

Electronic Theses and Dissertations

Ultrashort pulses are important for resolving electron motion in semiconductors to measure electronic transport properties. Electron wave packet motion is on the order of attoseconds, requiring temporal resolution on this time scale. However, a major constraint on femtosecond (1 fs = 10−15 s) and attosecond (1 as = 10−18 s) science is how well we can control and compress the excitation and measurement pulses in pump-probe experiments. Such ultrashort pulses require a broad spectrum with careful phase control across its bandwidth to minimize the duration. We discuss a new optical measurement technique that can directly measure the electric field that …

Optimization Of An Ultrasonic Non-Destructive Evaluation Technique For Laser Brazing, Dimitri Shinas

Electronic Theses and Dissertations

Brazing joins two sheets along a seam using a filler metal. In the brazing process, the filler metal is heated, along with the parts to be joined, to a temperature above the melting temperature of the filler material. This allows the filler metal to wet the surfaces of the parts to be joined through capillary action, resulting in the formation of metallic bonds, ultimately forming the joint.

Brazing, like all joining methods, is also susceptible to process variations. These process variations can include wear of the laser, plate misalignment, and external temperature changes. If left unchecked, such variations can eventually …

Ring Bose–Einstein Condensate Atomtronic Rotation Sensor, Oluwatobi I. Adeniji

Electronic Theses and Dissertations

We propose a design for an atomtronic rotation sensor consisting of an array of Bose– Einstein condensates (BECs) confined in a double–target–array potential. The purpose of the sensor is to measure the rotation speed, Ω_R, of the sensor’s rest frame with respect to the “fixed stars.” The atomtronic system consists of an ultracold gas of sodium atoms compressed, using laser light, into a thin horizontal sheet and subjected to a double–target– array potential within the horizontal plane. A “target” BEC consists of a disk–shaped condensate surrounded by a concentric ring–shaped condensate. A “double–target” BEC is two adjacent target …

Toward Novel Optical Functionalities Through Intelligent Photonic Structure Design, Robert J. Williamson

Electronic Theses and Dissertations

Photonic Metamaterials is a branch of electromagnetism that has been of great interest in recent years. This is further enhanced by the introduction of micro- and nanofabrication methods capable of producing metamaterial structures with which it is possible to create specific optical phenomena. The study of iso-frequency k-surfaces is of importance when discussing optical interactions with media. Previous research found evidence of materials exhibiting k-surfaces of bi-hyperbolic nature, though they failed to find any further hyperboloid dispersions. In this thesis we describe the k-surface topologies and including tri- and tetra-hyperbolic as well as analyze the polariton-interactions that cause these hyperbolic …