Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Doctoral Dissertations

Discipline
Institution
Keyword
Publication Year

Articles 1 - 30 of 1436

Full-Text Articles in Physical Sciences and Mathematics

Polymeric Peptide Mimics For Protein Delivery, Coralie Backlund Jan 2018

Polymeric Peptide Mimics For Protein Delivery, Coralie Backlund

Doctoral Dissertations

The plasma membrane is a major obstacle in the development and use of biomacromolecules for intracellular applications. Consequently, proteins with intracellular targets represent an enormous, yet under studied avenue for therapeutics. Extended research has aimed at facilitating intracellular delivery of exogenous proteins using protein transduction domains (PTDs), which allow transport of bioactive molecules into cells. Synthetic polymers, inspired by PTDs, provide a well-controlled platform to vary molecular architecture for structure activity relationship studies. Specifically, this thesis focuses on the use of ring-opening metathesis, a facile and efficient polymerization technique, through which we can vary structural parameters to optimize delivery of ...


Gas-Surface Interactions: Reactive And Non-Reactive Scattering, Azar Farjamnia Jan 2018

Gas-Surface Interactions: Reactive And Non-Reactive Scattering, Azar Farjamnia

Doctoral Dissertations

The adsorption and dissociation of small molecules on metal surfaces are key steps in many industrial reactions. A detailed understanding of the dynamics of these reactions provides us with the ability to control the outcome and efficacy of the reactions. The molecule-metal interactions will lead to reorientation, energy redistribution, or bond dissociation in the molecule. The process is strongly depending upon the initial conditions, i. e. the incident energy and vibrational state of the molecule, and the surface temperature. We use a fully quantum approach to compute the dissociative sticking probability of the molecules at zero overage, on the surface ...


Fully Differential Study Of Dissociative Capture In P + H₂ Collisions, Basu Ram Lamichhane Jan 2018

Fully Differential Study Of Dissociative Capture In P + H₂ Collisions, Basu Ram Lamichhane

Doctoral Dissertations

"In recent years, the key role of the projectile coherence properties has been studied in several ion-atom scattering processes. These studies strongly suggested that cross sections could be significantly affected by the projectile coherence properties, especially for fast, heavy ions. In the present study, we used such coherence effects as a tool to sensitively analyze the few- body dynamics of the scattering process. To this end, we performed three kinematically complete experiments on fragmentation of H2 by 75 keV proton impacts. A novel approach was used to analyze coherence and interference effects in the observed cross-sections. The idea was ...


Synthesis Of Novel Zwitterionic Polymers: From Functional Surfactants To Therapeutics, Matthew Skinner Jan 2018

Synthesis Of Novel Zwitterionic Polymers: From Functional Surfactants To Therapeutics, Matthew Skinner

Doctoral Dissertations

This dissertation describes the synthesis, characterization, and investigation of novel zwitterionic polymers containing phosphorylcholine (PC), sulfobetaine (SB), and functional choline phosphate (CP) zwitterions for use as surfactants, self-assembled nanomaterials, and therapeutics. Facile, reproducible, and modular chemistries were utilized for incorporating zwitterions into a range of polymer backbones, and strategies were developed for overcoming difficult challenges encountered in zwitterionic polymer synthesis, especially related to the varying solubility of zwitterions, hydrophobic polymers, and functional comonomers. Synthetic strategies utilized in this work give access to well-defined materials with narrow molecular weight distributions, tunable compositions and architectures, and versatile chemical functionality.

Chapter 2 describes ...


Equidimensional Adic Eigenvarieties For Groups With Discrete Series, Daniel Robert Gulotta '03 Jan 2018

Equidimensional Adic Eigenvarieties For Groups With Discrete Series, Daniel Robert Gulotta '03

Doctoral Dissertations

We extend Urban's construction of eigenvarieties for reductive groups G such that G(R) has discrete series to include characteristic p points at the boundary of weight space. In order to perform this construction, we define a notion of "locally analytic" functions and distributions on a locally Qp-analytic manifold taking values in a complete Tate Zp-algebra in which p is not necessarily invertible. Our definition agrees with the definition of locally analytic distributions on p-adic Lie groups given by Johansson and Newton.


3d Seismic Attribute Analysis And Machine Learning For Reservoir Characterization In Taranaki Basin, New Zealand, Aamer Alhakeem Jan 2018

3d Seismic Attribute Analysis And Machine Learning For Reservoir Characterization In Taranaki Basin, New Zealand, Aamer Alhakeem

Doctoral Dissertations

"The Kapuni group within the Taranaki Basin in New Zealand is a potential petroleum reservoir. The objective of the study includes building a sequential approach to identify different geological features and facies sequences within the strata, through visualizing the targeted formations by interpreting and correlating the regional geological data, 3D seismic, and well data by following a sequential workflow. First, seismic interpretation is performed targeting the Kapuni group formations, mainly, the Mangahewa C-sand and Kaimiro D-sand. Synthetic seismograms and well ties are conducted for structural maps, horizon slices, isopach, and velocity maps. Well log and morphological analyses are performed for ...


Using Latent Variable Models To Improve Causal Estimation, Huseyin Oktay Jan 2018

Using Latent Variable Models To Improve Causal Estimation, Huseyin Oktay

Doctoral Dissertations

Estimating the causal effect of a treatment from data has been a key goal for a large number of studies in many domains. Traditionally, researchers use carefully designed randomized experiments for causal inference. However, such experiments can not only be costly in terms of time and money but also infeasible for some causal questions. To overcome these challenges, causal estimation methods from observational data have been developed by researchers from diverse disciplines and increasingly studies using such methods account for a large share in empirical work. Such growing interest has also brought together two arguably separate fields: machine learning and ...


Supporting Scientific Analytics Under Data Uncertainty And Query Uncertainty, Liping Peng Jan 2018

Supporting Scientific Analytics Under Data Uncertainty And Query Uncertainty, Liping Peng

Doctoral Dissertations

Data management is becoming increasingly important in many applications, in particular, in large scientific databases where (1) data can be naturally modeled by continuous random variables, and (2) queries can involve complex predicates and/or be difficult for users to express explicitly. My thesis work aims to provide efficient support to both the "data uncertainty" and the "query uncertainty".

When data is uncertain, an important class of queries requires query answers to be returned if their existence probabilities pass a threshold. I start with optimizing such threshold query processing for continuous uncertain data in the relational model by (i) expediting ...


Emergent Phenomena In Quantum Critical Systems, Kun Chen Jan 2018

Emergent Phenomena In Quantum Critical Systems, Kun Chen

Doctoral Dissertations

A quantum critical point (QCP) is a point in the phase diagram of quantum matter where a continuous phase transition takes place at zero temperature. Low-dimensional quantum critical systems are strongly correlated, therefore hosting nontrivial emergent phenomena. In this thesis, we first address two decades-old problems on quantum critical dynamics. We then reveal two novel emergent phenomena of quantum critical impurity problems. In the first part of the thesis, we address the linear response dynamics of the $(2+1)$-dimensional $O(2)$ quantum critical universality class, which can be realized in the ultracold bosonic system near the superfluid (SF) to ...


On The Performance Of Adaptive Bitrate Streaming And Parallel Cloud Applications, Cong Wang Jan 2018

On The Performance Of Adaptive Bitrate Streaming And Parallel Cloud Applications, Cong Wang

Doctoral Dissertations

As shown in recent studies, video streaming is by far the biggest category of backbone Internet traffic in the US. As a measure to reduce the cost of highly over-provisioned physical infrastructures while remaining the quality of video services, many streaming service providers started to use cloud services, where physical resources can be dynamically allocated based on current demand.

In this dissertation, we seek to evaluate and improve the performance for both Adaptive Bitrate (ABR) video streaming and cloud applications. First, we present a set of measurement studies for ABR streaming applications. Using the data from the application, network, and ...


Eccentricity Modulation Of Precessional Variation In The Earth’S Climate Response To Astronomical Forcing: A Solution To The 41-Kyr Mystery, Rajarshi Roychowdhury Jan 2018

Eccentricity Modulation Of Precessional Variation In The Earth’S Climate Response To Astronomical Forcing: A Solution To The 41-Kyr Mystery, Rajarshi Roychowdhury

Doctoral Dissertations

The 41,000-year variability of Earth’s glacial cycles during the late Pliocene-early Pleistocene is usually attributed to variations in Earth’s obliquity (axial tilt). However, a satisfactory explanation for the lack of precessional variation in marine d18O records, a proxy for ocean temperature and ice-volume, remains contested. Here, a physically based climate model is used to show that the climatic effect of precession is muted in global isotope records due to two different mechanisms, with each dominating as a function of eccentricity. At low eccentricities (e0.019), the time-integrated summer insolation and number of positive degree-days impacting ...


The Molecular Basis Of Caspase-9 Inactivation By Pka And C-Abl Kinases, Banyuhay Paningbatan Serrano Jan 2018

The Molecular Basis Of Caspase-9 Inactivation By Pka And C-Abl Kinases, Banyuhay Paningbatan Serrano

Doctoral Dissertations

Caspases are the cysteine proteases that facilitate the fundamental pathway of programmed cell death or apoptosis. The activation and function of these powerful enzymes are tightly regulated to ensure the faithful execution of apoptosis and prevent untimely cell death. Many deadly human diseases such as cancer, neurodegeneration and autoimmune disorders have been associated with defective activation and faulty regulation of caspases. As such, caspases are considered as attractive drug targets, which when properly controlled, can lead to effective therapeutics for apoptosis-related diseases. Thus, comprehensive investigations of the structure, function and regulation of caspases are necessary to understand the complex mechanisms ...


Vibrated Squares As Equilibrium And Active Matter, Lee Askew Walsh Jan 2018

Vibrated Squares As Equilibrium And Active Matter, Lee Askew Walsh

Doctoral Dissertations

We study the effects of particle shape and self-propulsion on the collective behaviors of a two-dimensional granular fluid, using an experimental system of hard square grains. We energize the system by vibration, which, depending on particle shape, induces either isotropic diffusion or persistent self-propulsion in the particles. We use specially designed grains as a model system to study (i) the equilibrium packing of hard squares in two dimensions, (ii) the dynamics of athermal self-propelled particles, and (iii) the melting kinetics of an unconfined granular crystallite.

The first study concerns the phase diagram of a two-dimensional fluid of hard squares, which ...


Mitigation Of Environmental Hazards Of Sulfide Mineral Flotation With An Insight Into Froth Stability And Flotation Performance, Muhammad Badar Hayat Jan 2018

Mitigation Of Environmental Hazards Of Sulfide Mineral Flotation With An Insight Into Froth Stability And Flotation Performance, Muhammad Badar Hayat

Doctoral Dissertations

"Today's major challenges facing the flotation of sulfide minerals involve constant variability in the ore composition; environmental concerns; water scarcity and inefficient plant performance. The present work addresses these challenges faced by the flotation process of complex sulfide ore of Mississippi Valley type with an insight into the froth stability and the flotation performance. The first project in this study was aimed at finding the optimum conditions for the bulk flotation of galena (PbS) and chalcopyrite (CuFeS₂) through Response Surface Methodology (RSM). In the second project, an attempt was made to replace toxic sodium cyanide (NaCN) with the biodegradable ...


Aerogels For Energy Storage Applications: From Shape Memory Materials To Thermites And Explosives, Suraj Donthula Jan 2018

Aerogels For Energy Storage Applications: From Shape Memory Materials To Thermites And Explosives, Suraj Donthula

Doctoral Dissertations

"Aerogels are three dimensional highly porous solid objects that provide density reduction compared to dense objects. Those materials can have applications in different classes of energy storage and the two types that are focused in this dissertation are mechanical energy and thermal energy storage. Shape memory materials can store and recover elastic deformation energy when triggered by an external stimulus such as temperature. To incorporate those properties, shape memory polymeric aerogels (SMPA) were synthesized from a rigid isocyanurate containing triisocyanate (N3300 A) and four short oligomeric derivatives of ethylene glycol: H(OCH2CH2)nOH (1 ≤ n ≤ 4 ...


Cox-Type Model Validation With Recurrent Event Data, Muna Mohamed Hammuda Jan 2018

Cox-Type Model Validation With Recurrent Event Data, Muna Mohamed Hammuda

Doctoral Dissertations

"Recurrent event data occurs in many disciplines such as actuarial science, biomedical studies, sociology, and environment to name a few. It is therefore important to develop models that describe the dynamic evolution of the event occurrences. One major problem of interest to researchers with these types of data is models for the distribution function of the time between events occurrences, especially in the presence of covariates that play a major role in having a better understanding of time to events.

This work pertains to statistical inference of the regression parameter and the baseline hazard function in a Cox-type model for ...


Disorder At First-Order Classical And Quantum Phase Transitions, Ahmed Khalil Ibrahim Jan 2018

Disorder At First-Order Classical And Quantum Phase Transitions, Ahmed Khalil Ibrahim

Doctoral Dissertations

"This dissertation studies the effects of quenched disorder on classical, quantum and nonequilibrium phase transitions. After a short introduction which covers the basic concepts of phase transitions, finite-size scaling and random disorder, the dissertation focuses on four separate but related projects. First, we investigate the influence of quenched disorder with long-range spatial correlations on the nonequilibrium phase transitions in the contact process. We show that the long-range correlations increase the probability to find rare atypical regions in the sample. This leads to enhanced Griffiths singularities and changes the universality class of the transition.

Project 2 and 3 focus on disorder ...


Evaluation Of The Redesign Of A Stem Gatekeeper Course, General Chemistry I, Incorporating Active-Learning Strategies And Implementation Of A Student-Choice Model, Travis Rae Mcdowell Jan 2018

Evaluation Of The Redesign Of A Stem Gatekeeper Course, General Chemistry I, Incorporating Active-Learning Strategies And Implementation Of A Student-Choice Model, Travis Rae Mcdowell

Doctoral Dissertations

"The first courses freshman university students typically enroll in are the introductory science and math, courses that bridge from and build upon their prior educational experiences. These introductory courses often have large enrollment lectures coupled with supplemental sessions to teach using traditional educational practices, which may operate counter to the attitudes and culture of the students who take them. To address this, the general chemistry faculty through collaboration with a team of educational specialists initiated a redesign of the general chemistry course, which primarily serves first-year undergraduates. The redesign efforts included changes such as reducing lecture time and placing emphasis ...


Evolving Specialization In An Agent-Based Model Without Task-Switching Costs, Shane Robert Meyer Jan 2018

Evolving Specialization In An Agent-Based Model Without Task-Switching Costs, Shane Robert Meyer

Doctoral Dissertations

"This work examines the possibility of evolving the phenotypic specialization associated with division of labor in an agent-based model without task-switching costs. The model examines two groups competing for vital resources, where members of one group are capable of sharing resources with other agents in their group. Agents attempt to collect resources which allow them to reproduce, with more resources leading to a greater number of offspring by asexual reproduction. Four variants of the model are examined, with combinations of one or two resources and the presence of a foraging risk. The presence of the foraging risk can lead to ...


Hdg Methods For Dirichlet Boundary Control Of Pdes, Yangwen Zhang Jan 2018

Hdg Methods For Dirichlet Boundary Control Of Pdes, Yangwen Zhang

Doctoral Dissertations

"We begin an investigation of hybridizable discontinuous Galerkin (HDG) methods for approximating the solution of Dirichlet boundary control problems for PDEs. These problems can involve atypical variational formulations, and often have solutions with low regularity on polyhedral domains. These issues can provide challenges for numerical methods and the associated numerical analysis. In this thesis, we use an existing HDG method for a Dirichlet boundary control problem for the Poisson equation, and obtain optimal a priori error estimates for the control in the high regularity case. We also propose a new HDG method to approximate the solution of a Dirichlet boundary ...


Machine Learning Techniques Implementation In Power Optimization, Data Processing, And Bio-Medical Applications, Khalid Khairullah Mezied Al-Jabery Jan 2018

Machine Learning Techniques Implementation In Power Optimization, Data Processing, And Bio-Medical Applications, Khalid Khairullah Mezied Al-Jabery

Doctoral Dissertations

"The rapid progress and development in machine-learning algorithms becomes a key factor in determining the future of humanity. These algorithms and techniques were utilized to solve a wide spectrum of problems extended from data mining and knowledge discovery to unsupervised learning and optimization. This dissertation consists of two study areas. The first area investigates the use of reinforcement learning and adaptive critic design algorithms in the field of power grid control. The second area in this dissertation, consisting of three papers, focuses on developing and applying clustering algorithms on biomedical data. The first paper presents a novel modelling approach for ...


Integrated Study On The Applicability Of Co₂-Eor In Unconventional Liquids Rich Reservoirs, Dheiaa Khafief Khashan Alfarge Jan 2018

Integrated Study On The Applicability Of Co₂-Eor In Unconventional Liquids Rich Reservoirs, Dheiaa Khafief Khashan Alfarge

Doctoral Dissertations

"Unconventional Liquids Rich Reservoirs (ULR) such as Bakken, Niobrara, and Eagle Ford have become the main target for oil and gas investors as conventional formations started to deplete and diminish in number. These unconventional plays have a huge oil reserve; however, the predicted primary oil recovery is still low as an average of 7.5 %. Unconventional Improved Oil Recovery (UIOR) techniques are still a new concept in the oil industry because there is no commercial project for any IOR technique so far. Injecting carbon dioxide (CO₂) might be the most potential strategy to improve oil recovery in such complex plays ...


Lithospheric Layering And Thickness Beneath The Contiguous United States, Lin Liu Jan 2018

Lithospheric Layering And Thickness Beneath The Contiguous United States, Lin Liu

Doctoral Dissertations

"The Upper Mississippi Embayment (UME), where the seismically active New Madrid Seismic Zone resides, experienced two phases of subsidence commencing in the Late Precambrian and Cretaceous, respectively. To provide new constraints on models proposed for the mechanisms responsible for the subsidence, we computed and stacked P-to-S receiver functions recorded by 49 USArray and other seismic stations located in the UME and the adjacent Ozark Uplift and modeled Bouguer gravity anomaly data. The inferred thickness, density, and Vp/Vs of the upper and lower crustal layers suggest that the UME is characterized by a mafic and high-density upper crustal layer of ...


Electrodeposited Semiconductor Nanostructures & Epitaxial Thin Films For Flexible Electronics, Naveen Kumar Mahenderkar Jan 2018

Electrodeposited Semiconductor Nanostructures & Epitaxial Thin Films For Flexible Electronics, Naveen Kumar Mahenderkar

Doctoral Dissertations

"Single-crystal Si is the bedrock of semiconductor devices due to the high crystalline perfection which minimizes electron-hole recombination, and the dense native silicon oxide which minimizes surface states. To expand the palette of electronic materials beyond planar Si, an inexpensive source of highly ordered material is needed that can serve as an inert substrate for the epitaxial growth of grain boundary-free semiconductors, photonic materials, and superconductors. There is also a need for a simple, inexpensive, and scalable fabrication technique for the growth of semiconductor nanostructures and thin films. This dissertation focuses on the fabrication of semiconducting nanowires (polycrystalline Ge & epitaxial ...


Data Stream Algorithms For Large Graphs And High Dimensional Data, Hoa Vu Jan 2018

Data Stream Algorithms For Large Graphs And High Dimensional Data, Hoa Vu

Doctoral Dissertations

In contrast to the traditional random access memory computational model where the entire input is available in the working memory, the data stream model only provides sequential access to the input. The data stream model is a natural framework to handle large and dynamic data. In this model, we focus on designing algorithms that use sublinear memory and a small number of passes over the stream. Other desirable properties include fast update time, query time, and post processing time.

In this dissertation, we consider different problems in graph theory, combinatorial optimization, and high dimensional data processing.

The first part of ...


Surface Functionalization Of Fabrics And Threads For Smart Textiles, Morgan Baima Jan 2018

Surface Functionalization Of Fabrics And Threads For Smart Textiles, Morgan Baima

Doctoral Dissertations

The future of electronics is moving toward wearable devices and therefore requires a shift away from hard, inflexible materials towards fibers, threads, and fabrics that conform to the shape of the body. Therefore new methods for incorporating textiles as electronic components are needed to replace conventional processing techniques used with smooth, flat substrates like glass, silicon, and many polymers. Toward this end, this work investigates different methods that can be used to tune textile surfaces for electronic functionality, including weaving, solution grafting, and initiated chemical vapor deposition (iCVD). While all of these methods were used to make triboelectrically-active textiles, iCVD ...


Model-Based Predictive Analytics For Additive And Smart Manufacturing, Zhuo Yang Jan 2018

Model-Based Predictive Analytics For Additive And Smart Manufacturing, Zhuo Yang

Doctoral Dissertations

Qualification and certification for additive and smart manufacturing systems can be uncertain and very costly. Using available historical data can mitigate some costs of producing and testing sample parts. However, use of such data lacks the flexibility to represent specific new problems which decreases predictive accuracy and efficiency. To address these compelling needs, in this dissertation modeling techniques are introduced that can proactively estimate results expected from additive and smart manufacturing processes swiftly and with practical levels of accuracy and reliability. More specifically, this research addresses the current challenges and limitations posed by use of available data and the high ...


Essays In Financial Economics: Announcement Effects In Fixed Income Markets, James J. Forest Jan 2018

Essays In Financial Economics: Announcement Effects In Fixed Income Markets, James J. Forest

Doctoral Dissertations

ABSTRACT

ESSAYS IN FINANCIAL ECONOMICS: ANNOUNCEMENT EFFECTS IN FIXED INCOME MARKETS

PHD IN FINANCE MAY 2018

JAMES J FOREST

B.A., FRAMINGHAM STATE UNIVERSITY

M.S., NORTHEASTERN UNIVERSITY

Ph.D., UNIVERSITY OF MASSACHUSETTS – AMHERST

Directed by: Professor Hossein B. Kazemi

This dissertation demonstrates the use of empirical techniques for dealing with modeling issues that arise when analyzing announcement effects in fixed income markets. It describes empirical challenges in achieving unbiased and efficient parameter estimates and shows the importance of modelling a wide range of macroeconomic announcement effects to avoid omitted variable bias. Employing techniques common in Macroeconomics, financial market researchers ...


Quantum Phase Transitions In Disordered Boson Systems, Zhiyuan Yao Jan 2018

Quantum Phase Transitions In Disordered Boson Systems, Zhiyuan Yao

Doctoral Dissertations

In this dissertation, we study the superfluid-insulator quantum phase transition in disordered boson systems. Recently, there has been considerable controversy over the validity of the scaling relations of the superfluid--Bose-glass quantum phase transition in three dimensions. Results from experimental and numerical studies on disordered quantum magnets contradict the scaling relations and the associated conventional scaling hypothesis for the singular part of the free energy. We determine various critical exponents of the superfluid--Bose-glass quantum phase transition in three-dimensional disordered Bose-Hubbard model through extensive Monte Carlo simulations. Our numerical study shows the previous studies on disordered quantum magnets were performed outside the ...


The Dissociative Chemisorption Of Methane And Its Isotopologues On Metal Surfaces, Han Guo Jan 2018

The Dissociative Chemisorption Of Methane And Its Isotopologues On Metal Surfaces, Han Guo

Doctoral Dissertations

The dissociative chemisorption of small molecules on metal surfaces is an important step in many heterogeneous catalytic processes, and has received considerable scientific attention. In this thesis, a quantum approach based on the reaction path Hamiltonian is used to explore the dissociative chemisorption of methane and its deuterated isotopologues on several metal surfaces.

The theoretical approach is described in Chapter 2. This approach treats all 15 degrees of freedom of the methane molecule, and includes the effects of lattice motion, allowing us to examine the translational and vibrational enhancements, mode- and bond-selectivity and the surface temperature dependence observed in experiments ...