Physical Sciences and Mathematics Commons^™

Physicochemical And Toxicological Assessment Of Antimicrobial Ε-Polylysine-Pectin Complexes, Cynthia L. Lopez Pena

Doctoral Dissertations

ε-Polylysine is an appealing FDA-approved, all natural antimicrobial biopolymer effective against a wide range of microorganisms. Its implementation is greatly limited by its strong cationic charge, which has been linked to instability in food systems, perceived astringency and bitterness, and the ability to inhibit lipid digestion. Previous studies have shown that controlled complexation of ε-polylysine with anionic pectin is able to prevent instability and astringency in simplified model food systems, while maintaining the antimicrobial character of polylysine. Isothermal titration calorimetry, micro-electrophoresis, microscopy, and turbidity analyses of the stability of electrostatic pectin-polylysine complexes in the presence of strongly anionic κ-carrageenan, and …

A Platform For Scalable Low-Latency Analytics Using Mapreduce, Boduo Li

Doctoral Dissertations

Today, the ability to process "big data" has become crucial to the information needs of many enterprise businesses, scientific applications, and governments. Recently, there have been increasing needs of processing data that is not only "big" but also "fast". Here "fast data" refers to high-speed real-time and near real-time data streams, such as Twitter feeds, search query streams, click streams, impressions, and system logs. To handle both historical data and real-time data, many companies have to maintain multiple systems. However, recent real-world case studies show that maintaining multiple systems cause not only code duplication, but also intensive manual work to …

Time-And Polarization-Resolved Photoluminescence Studies Of Directional Coupling In Isolated Semiconductor Nanostructures, Joelle A. Labastide

Doctoral Dissertations

TIME-AND POLARIZATION-RESOLVED STUDIES OF DIRECTIONAL COUPLING IN ISOLATED SEMICONDUTOR NANOSTRUCTURES MAY 2015 JOELLE A. LABASTIDE, B.S. UNIVERSITY OF MASSACHUSESSTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMERST Directed by Professor Michael D. Barnes Development of new materials and assembly strategies for organic semiconductor-based optoelectronic materials is a problem of great interest worldwide, as researchers seek to resolve the questions pertinent to the creation of inexpensive, reliable, efficient, and stable active layer components. Organic semiconductors as the basis for photovoltaic active layers show significant promise for these applications. However, there is still much that needs to be understood about the molecular scale structural …

Obstruction Criteria For Modular Deformation Problems, Jeffrey Hatley Jr

Doctoral Dissertations

For a cuspidal newform f of weight k at least 3 and a prime p of the associated number field K_f, the deformation problem for its associated mod p Galois representation is unobstructed for all primes outside some finite set. Previous results gave an explicit bound on this finite set for f of squarefree level; we modify this bound and remove the squarefree hypothesis. We also show that if the p-adic deformation problem for f is unobstructed, then f is not congruent mod p to a newform of lower level.

Design And Synthesis Of Polybetaines For Nonfouling Applications, Katherine A. Gibney

Doctoral Dissertations

Polybetaines represent a unique class of charged polymers. These polymers contain both a positive and negative charge on each repeat unit so that the polymer itself is charge-neutral. The highly polar nature of the betaine group gives rise to biocompatibility and strong hydration, making polybetaines attractive biomaterials. Ring-opening metathesis polymerization’s utility in polymerizing charged monomers opened up a new avenue to obtain polybetaines. Dual-functional polybetaines obtained by ring-opening the imide group of cationic oxanorbornene-based polymers were previously described. Here, that chemistry is expanded upon to create a broad library of new betaines. First, the ring-opening reaction in oxanorbornene imides is …

Tunable Photonic Multilayers From Stimulus-Responsive, Photo-Crosslinkable Polymers, Maria C. Chiappelli

Doctoral Dissertations

This dissertation describes the synthesis of photo-crosslinkable copolymers and their utilization for the fabrication and testing of tunable and responsive one-dimensional (1D) photonic multilayers. Photonic multilayers exhibit structural color due to the interference of incident light at layer interfaces, providing a convenient route towards optically responsive materials that do not rely on potentially light- or oxygen-sensitive chromophore-containing pigments and dyes. A fabrication technique based on sequential spin-coating and crosslinking of photo-crosslinkable polymers is used to assemble tunable and responsive photonic multilayers. Chapter One introduces the fundamental underlying principles of 1D photonic structures and explores their importance in a variety of …

Robust Mobile Data Transport: Modeling, Measurements, And Implementation, Yung-Chih Chen

Doctoral Dissertations

Advances in wireless technologies and the pervasive influence of multi-homed devices have significantly changed the way people use the Internet. These changes of user behavior and the evolution of multi-homing technologies have brought a huge impact to today's network study and provided new opportunities to improve mobile data transport. In this thesis, we investigate challenges related to human mobility, with emphases on network performance at both system level and user level. More specifically, we seek to answer the following two questions: 1) How to model user mobility in the networks and use the model for network provisioning? 2) Is it …

Sediment Records From Coastal Ponds: Temporal Archives Of Storm Inundation And Environmental Change, Christine M. Brandon

Doctoral Dissertations

Hurricanes are powerful storms that can cause billions of dollars in damage and kill many people when they strike populated coastal areas. Understanding how frequently coastal cities can expect storms of a certain magnitude would help inform more effective mitigation and adaptation strategies. Unfortunately, current estimates of hurricane frequency rely on numerical models based on weather observations that, on the east coast of the United States, only extend ~150 years into the past. While this is sufficient for estimating the characteristics (i.e. wind speed and storm surge height) of annual or decadal storms, the properties of larger, rarer, and more …

Experimental Test Of Genetic Rescue In Isolated Populations Of Brook Trout, Zachary L. Robinson

Masters Theses

Translocations are an important aspect of the management of natural populations in an increasingly fragmented landscape. Maintaining connectivity and gene flow is beneficial for both contemporary fitness and adaptive potential in the face of environmental change. Genetic rescue (GR) can alleviate inbreeding depression, genetic load, and increase adaptive potential of populations. Here, I have translocated 10 (5 of each sex) brook trout (Salvelinus fontinalis) to four geographically proximate and environmentally similar fragmented stream-dwelling populations of brook trout in Virginia to test for genetic rescue. The translocated brook trout contributed to more families than would be expected under neutral …

Arctic Environmental Change Across The Pliocene-Pleistocene Transition, Benjamin Andrew Keisling

Masters Theses

Environmental change in the Arctic proceeds at an unprecedented rate. The Pliocene epoch (5-2.65 million years ago) represents an analog for future climate conditions, with pCO₂ and continental configurations similar to present. Yet conditions in the Pliocene Arctic are poorly characterized because of sparse sampling. The records that do exist indicate periods of extreme warmth, as well as the first expansion of large ice-sheets in the Northern Hemisphere, took place from the end of the Pliocene into the early Pleistocene. Understanding these deposits and their implications for our future requires developing a sense of climatic evolution across the …

Design And Implementation Of Digital Information Security For Physical Documents, Pengcheng Wang

Masters Theses

The objective of this thesis is to improve the security for physical paper documents. Providing information security has been difficult in environments that rely on physical paper documents to implement business processes. Our work presents the design of a digital information security system for paper documents, called "CryptoPaper", that uses 2-dimensional codes to represent data and its security properties on paper. A special scanner system is designed for "CryptoPaper" which uses image recognition techniques and cloud-based access control to display plaintext of encrypted and encoded data to authorized users.

Assessing Mammal And Bird Biodiversity And Habitat Occupancy Of Tiger Prey In The Hukaung Valley Of Northern Myanmar, Hla Naing

Masters Theses

I used results from camera traps set for tigers (Panthera tigris) during 2001-2011 in the Hukaung Valley Wildlife Sanctuary of northern Myanmar to assess overall biodiversity of large mammal and bird species, and to identify differences in photo rates inside and outside of the most protected core area of the Sanctuary. A total of 403 camera stations were deployed during October-July in the dry seasons of 2001-2011, 260 inside the Core area and 143 Outside. From 10,750 trap-nights I obtained 2,077 independent photos of wildlife species and 699 of domestic animals and humans, including 35 species of wild …

Dissolution, Ocean Acidification And Biotic Extinctions Prior To The Cretaceous/Paleogene (K/Pg) Boundary In The Tropical Pacific, Serena Dameron

Masters Theses

The several million years preceding the Cretaceous/Paleogene (K/Pg) boundary has been the focus of many studies. Changes in ocean circulation and sea level, extinctions, and major volcanic events have all been documented for this interval. Important research questions these changes raise include the climate dynamics during the warm, but not hot, time after the decay of the Late Cretaceous greenhouse interval and the stability of ecosystems prior to the mass extinctions at the end-Cretaceous.

I document several biotic perturbations as well as changes in ocean circulation during the Maastrichtian stage of the latest Cretaceous that question whether the biosphere was …

When Does Linear Stability Not Exclude Nonlinear Instability?, Panos Kevrekidis, D. E. Pelinovsky, A. Saxena

Panos Kevrekidis

We describe a mechanism that results in the nonlinear instability of stationary states even in the case where the stationary states are linearly stable. This instability is due to the nonlinearity-induced coupling of the linearization’s internal modes of negative energy with the continuous spectrum. In a broad class of nonlinear Schrödinger equations considered, the presence of such internal modes guarantees the nonlinear instability of the stationary states in the evolution dynamics. To corroborate this idea, we explore three prototypical case examples: (a) an antisymmetric soliton in a double-well potential, (b) a twisted localized mode in a one-dimensional lattice with cubic …

The Expected Total Curvature Of Random Polygons, Jason Cantarella, Alexander Y. Grosberg, Robert Kusner, Clayton Shonkwiler

Robert Kusner

We consider the expected value for the total curvature of a random closed polygon. Numerical experiments have suggested that as the number of edges becomes large, the difference between the expected total curvature of a random closed polygon and a random open polygon with the same number of turning angles approaches a positive constant. We show that this is true for a natural class of probability measures on polygons, and give a formula for the constant in terms of the moments of the edgelength distribution.

We then consider the symmetric measure on closed polygons of fixed total length constructed by …

Stability And Tunneling Dynamics Of A Dark-Bright Soliton Pair In A Harmonic Trap, E. T. Karamatskos, J. Stockhofe, Panos Kevrekidis, P. Schmelcher

Panos Kevrekidis

http://journals.aps.org/pra/abstract/10.1103/PhysRevA.91.043637

Thermo-Responsive Poly(N-Isopropylacrylamide) And Its Critical Solution Temperature Type Behavior In Presence Of Hydrophilic Ionic Liquids, Purnendu K. Nayak

Masters Theses

Thermo-responsive homopolymer poly(N-isopropylacrylamide), is a widely studied and used polymer. Our recent observations on thermal behavior of aqueous solutions of this polymer requires a short overview of existing results in order to understand the formation of different phases, both stable and unstable with the addition of hydrophilic Ionic liquids (ILs) 1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]), 1-Butyl-3-methylimidazolium acetate ([BMIM][OAc]) and 1-Butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) to the system. PNIPAM is soluble in cold water due to its inter- and intramolecular hydrogen bonding but phase separates upon heating at T > 32 , which is its lower critical solution temperature (LCST). PNIPAM exists in an …

Hydrogeological Control On Spatial Patterns Of Groundwater Seepage In Peatlands, Danielle K. Hare

Masters Theses

Groundwater seepage to surface water is an important process to peatland ecosystems; however, the processes controlling seepage zone distribution and magnitude are not well understood. This lack of process-based understanding makes degraded peatland ecosystems difficult to restore and problematic for resource managers developing a sustainable design. Degraded peatlands, particularly abandoned cranberry farms, often have drainage ditches, applied surface sand, and decreased stream sinuosity to artificially lower the water table and support agriculture. These modifications disconnect the surface and groundwater continuum, which decreases thermal buffering of surface water significantly. The combination of a decreased influx of thermally buffered groundwater, a naturally …

Catalytic Methane Dissociative Chemisorption Over Pt(111): Surface Coverage Effects And Reaction Path Description, Inara Colon-Diaz

Masters Theses

Density functional theory calculations were performed to study the dissociative chemisorption of methane over Pt(111) with the idea of finding the minimum energy path for the reaction and its dependence on surface coverage. Two approaches were used to evaluate this problem; first, we used different sizes of supercells (2x2, 3x3, 4x4) in order to decrease surface coverage in the absence of pre-adsorbed H and CH₃ fragments to calculate the energy barriers of dissociation. The second approach uses a 4x4 unit cell and surface coverage is simulated by adding pre-absorbed H and CH₃ fragments. Results for both approaches show …

The Effect Of A New Hospital-Based Congestive Heart Failure Care Protocol On Rate Of 30-Day Readmission Among Chf Patients, Eric A. Cohen

Masters Theses

Approximately 20% of congestive heart failure (CHF) patients are readmitted within 30 days of hospital discharge, a rate which may be affected by in-hospital and post-discharge care. Reducing this rate is important to hospitals, both to improve outcomes and to avoid reductions in Medicare reimbursement. Assessing outcomes within a short post-discharge window best measures the impact of the care, planning, and followup of that admission; but most research on the effects of changes in CHF care has measured outcomes over periods longer than 30 days, adding the unpredictable long-term course of CHF to the factors affecting the outcome. As well, …

Epistemological Databases For Probabilistic Knowledge Base Construction, Michael Louis Wick

Doctoral Dissertations

Knowledge bases (KB) facilitate real world decision making by providing access to structured relational information that enables pattern discovery and semantic queries. Although there is a large amount of data available for populating a KB; the data must first be gathered and assembled. Traditionally, this integration is performed automatically by storing the output of an information extraction pipeline directly into a database as if this prediction were the ``truth.'' However, the resulting KB is often not reliable because (a) errors accumulate in the integration pipeline, and (b) they persist in the KB even after new information arrives that could rectify …

Search For Contact Interactions And Large Extra Dimensions In Dimuon Events From Pp Collisions At √S = 8 Tev With The Atlas Detector, Tüli̇n Varol

Doctoral Dissertations

A search is conducted for non-resonant new phenomena in the dimuon final states, originating from either contact interactions or large extra spatial dimensions. The proton-proton collision data recorded by the ATLAS detector at the LHC in 2012 at √s = 8 TeV, corresponding to an integrated luminosity of 20.5 fb^-1, is used. The dimuon invariant mass spectrum is a discriminating variable in both searches, with the contact interaction search additionally utilizing the dimuon forward-backward asymmetry. No significant deviations from the Standard Model expectation are observed. Lower limits are set on the new physics parameters of interest at 95% …

Long Range Motion Estimation And Applications, Laura Sevilla-Lara

Doctoral Dissertations

Finding correspondences between images underlies many computer vision problems, such as op- tical flow, tracking, stereovision and alignment. Finding these correspondences involves formulating a matching function and optimizing it. This optimization process is often gradient descent, which avoids exhaustive search, but relies on the assumption of being in the basin of attraction of the right local minimum. This is often the case when the displacement is small, and current methods obtain very accurate results for small motions. However, when the motion is large and the matching function is abrupt this assumption is less likely to be true. One traditional way …

Design, Synthesis, And Bio Relevant Applications Of Zwitterionic Amphiphilic Macromolecular Assemblies, Rajasekhar Reddy Rami Reddy

Doctoral Dissertations

Supramolecular nanoassemblies capable of reducing non-specific interactions with biological macromolecules, such as proteins, are of great importance for various biological applications especially for targeted drug delivery therapeutics. Recently, zwitterionic materials have been shown to reduce non-specific interactions with biomolecules, owing both to their charge neutrality and their ability to form strong hydration layer around zwitterions via electrostatic interactions. This dissertation focuses on design, synthesis, thorough characterization, and applications of zwitterionic amphiphilic dendrimers and polymeric materials. Firstly, A new triazole-based zwitterionic moiety was conceived and incorporated as the hydrophilic functionality in facially amphiphilic dendrons. Self-assembly characteristics and the structural and functional …

Design, Syntheses And Study Of Bodipy-Based Materials For Use As Electron Transporters In Organic Electronics, Ambata Poe

Doctoral Dissertations

Organic photovoltaics (OPVs) are desirable for the harvesting of solar energy. They provide distinct advantages over their inorganic counterparts, especially the high absorption coefficients of organic materials and their ability to be processed using inexpensive solution methods. This allows for potential development of lightweight and flexible devices for portable electronics. One of the drawbacks of organic photovoltaics is the low power conversion efficiency of the devices. Efforts to improve the efficiency often take place through molecular design of the electron rich donor material to improve light absorption of the active layer. However, significantly less effort has been put into modifying …

X-Band Dual Polarization Phased-Array Radar For Meteorological Applications, Krzysztof Orzel

Doctoral Dissertations

This dissertation details the development and operation of a novel dual-polarized Phase-Tilt Weather Radar (PTWR) designed for meteorological applications. The use of radar has a well-documented history in detection and classification of weather phenomena, but due to the limited mechanical scanning speed, its usage for severe weather observations remains far from ideal. The PTWR utilizes phased-array technology and provides unique capabilities such as smart scanning, fast scan update, and tracking. This technology is considered a candidate for a replacement and consolidation of the current US weather and surveillance radar networks. The dissertation can be divided into three parts. First, the …

Learning With Joint Inference And Latent Linguistic Structure In Graphical Models, Jason Narad

Doctoral Dissertations

Constructing end-to-end NLP systems requires the processing of many types of linguistic information prior to solving the desired end task. A common approach to this problem is to construct a pipeline, one component for each task, with each system's output becoming input for the next. This approach poses two problems. First, errors propagate, and, much like the childhood game of "telephone", combining systems in this manner can lead to unintelligible outcomes. Second, each component task requires annotated training data to act as supervision for training the model. These annotations are often expensive and time-consuming to produce, may differ from each …

Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence

Doctoral Dissertations

Advances in the synthetic strategies of engineered nanomaterials, multifunctional molecules and polymers have opened pathways for the development of functional nanomaterials having unique optoelectronic, mechanical, and biological properties. By designing the chemistry of surface ligands, the organic interface of nanoparticles, one can further the versatility and utilization of engineered nanomaterials, opening pathways for breakthroughs in sensing, catalysis, and delivery using nanomaterials. This thesis describes the synthesis and characterization of small molecule and polymer ligand functionalized inorganic nanoparticles (e.g., metal, semiconducting). Embedding specific chemical functionality into the ligand periphery of nanoparticles enables the resulting functional nanoparticles to react selectively …

Effectiveness Of Cloud Services For Scientific And Vod Applications, Dilip Kumar Krishnappa

Doctoral Dissertations

Cloud platforms have emerged as the primary data warehouse for a variety of applications, such as DropBox, iCloud, Google Music, etc. These applications allow users to store data in the cloud and access it from anywhere in the world. Commercial clouds are also well suited for providing high-end servers for rent to execute applications that require computation resources sporadically. Cloud users only pay for the time they actually use the hardware and the amount of data that is transmitted to and from the cloud, which has the potential to be more cost effective than purchasing, hosting, and maintaining dedicated hardware. …

Stimuli-Responsive Supramolecular Assembly, Disassembly And Implications, Jing Guo

Doctoral Dissertations

Stimuli-responsive systems have attracted wide interest due to their applications in a variety of areas such as drug delivery and sensing. Stimuli-responsive systems that are triggered by secondary biological changes have been studied extensively. Primary biological changes, such as protein imbalances and enzymatic activity, are intrinsic to certain types of diseases, and thus have drawn increasing attention in triggering stimuli-responsive systems in areas such as drug delivery. This thesis first provides a concept of increasing stimuli-responsive selectivity by designing a system that only responds in the concurrent presence of two complementary primary biological stimuli, protein and enzyme. A dendritic assembly …