Physical Sciences and Mathematics Commons^™

Gravitational Wave Production Through Decay Of The Inflaton Into Intermediary Fields During Slow Roll Inflation, Jessica Lauren Cook

Open Access Dissertations

This dissertation looks for possible observable signals of tensor metric perturbations sourced during slow roll inflation from decay of the inflaton field into other intermediary fields. We focus on two main scenarios, one of explosive production of intermediary fields for a short period during inflation and another of prolonged production of vectors due to a derivative coupling of the vectors with the inflaton field. We only find a possible observable signal of tensor perturbations in the second case.

Query-Time Optimization Techniques For Structured Queries In Information Retrieval, Marc-Allen Cartright

Open Access Dissertations

The use of information retrieval (IR) systems is evolving towards larger, more complicated queries. Both the IR industrial and research communities have generated significant evidence indicating that in order to continue improving retrieval effectiveness, increases in retrieval model complexity may be unavoidable. From an operational perspective, this translates into an increasing computational cost to generate the final ranked list in response to a query. Therefore we encounter an increasing tension in the trade-off between retrieval effectiveness (quality of result list) and efficiency (the speed at which the list is generated). This tension creates a strong need for optimization techniques to …

The Security And Privacy Implications Of Energy-Proportional Computing, Shane S. Clark

Open Access Dissertations

The parallel trends of greater energy-efficiency and more aggressive power management are yielding computers that inch closer to energy-proportional computing with every generation. Energy-proportional computing, in which power consumption scales closely with workload, has unintended side effects for security and privacy. Saving energy is an unqualified boon for computer operators, but it is becoming easier to identify computing activities by observing power consumption because an energy-proportional computer reveals more about its workload.

This thesis demonstrates the potential for system-level power analysis---the inference of a computers internal states based on power observation at the "plug." It also examines which hardware components …

Understanding The Links Between Human Health And Climate Change: Agricultural Productivity And Allergenic Pollen Production Of Timothy Grass(Phleum Pratense L.) Under Future Predicted Levels Of Carbon Dioxide And Ozone, Jennifer M. Albertine

Open Access Dissertations

The prevalence of allergic disease is expected to increase with climate change. Grasses, which have highly allergenic pollen, are widely distributed across the globe. Changes in production and allergen content of grass pollen have not been specifically investigated. We tested the effects of elevated carbon dioxide and ozone on growth, pollen and allergen production of Timothy grass (Phleum pratense L.). Timothy is also used as an agricultural forage crop so changes in plant productivity can also affect humans indirectly. Plants were fumigated in eight chambers at two concentrations of ozone (O₃; 30 and 80 ppb) and carbon dioxide …

Exploring Privacy And Personalization In Information Retrieval Applications, Henry A. Feild

Open Access Dissertations

A growing number of information retrieval applications rely on search behavior aggregated over many users. If aggregated data such as search query reformulations is not handled properly, it can allow users to be identified and their privacy compromised. Besides leveraging aggregate data, it is also common for applications to make use of user-specific behavior in order to provide a personalized experience for users. Unlike aggregate data, privacy is not an issue in individual personalization since users are the only consumers of their own data.

The goal of this work is to explore the effects of personalization and privacy preservation methods …

Open Books On Contact Three Orbifolds, Daniel Herr

Open Access Dissertations

In 2002, Giroux showed that every contact structure had a corresponding open book decomposition. This was the converse to a previous construction of Thurston and Winkelnkemper, and made open books a vital tool in the study of contact three-manifolds. We extend these results to contact orbifolds, i.e. spaces that are locally diffeomorphic to the quotient of a contact manifold and a compatible finite group action. This involves adapting some of the main concepts and constructions of three dimensional contact geometry to the orbifold setting.

Clustering, Reorientation Dynamics, And Proton Transfer In Glassy Oligomeric Solids, Jacob Allen Harvey

Open Access Dissertations

We have modelled structures and dynamics of hydrogen bond networks that form from imidazoles tethered to oligomeric aliphatic backbones in crystalline and glassy phases. We have studied the behavior of oligomers containing 5 or 10 imidazole groups. These systems have been simulated over the range 100-900 K with constantpressure molecular dynamics using the AMBER 94 force field, which was found to show good agreement with ab initio calculations on hydrogen bond strengths and imidazole rotational barriers. Hypothetical crystalline solids formed from packed 5-mers and 10-mers melt above 600 K, then form glassy solids upon cooling. Viewing hydrogen bond networks as …

Ecohydrologic Impacts Of Climate And Land Use Changes On Watershed Systems: A Multi-Scale Assessment For Policy, Paul A. Ekness

Open Access Dissertations

Maintaining flows and quality of water resources is critical to support ecosystem services and consumptive needs. Understanding impacts of changes in climate and land use on ecohydrologic processes in a watershed is vital to sustaining water resources for multiple uses. This study completes a continental and regional scale assessment using statistical and simulation modeling to investigate ecohydrologic impacts within watershed systems.

Watersheds across the continental United States have diverse hydrogeomorphic characters, mean temperatures, soil moistures, precipitation and evaporation patterns that influence runoff processes. Changes in climate affect runoff by impacting available soil moisture, evaporation, precipitation and vegetative patterns. A one …

Conditional Gaussian Fluctuations And Refined Asymptotics Of The Spin In The Phase-Coexistence Region, Jingran Li

Open Access Dissertations

In this dissertation four results are presented on the fluctuations of the spin per site around the thermodynamic magnetization in the mean-field Blume-Capel model, a basic model in statistical mechanics. The first two results refine the main theorem in a 2010 paper by R. S. Ellis, J. Machta, and P. T. Otto published in Annals of Applied Probability 20 (2010) 2118-2161. This paper provides the first rigorous confirmation of the statistical mechanical theory of finite-size scaling for a mean-field model. The first main result studies the asymptotics of the centered, finite-size magnetization, giving its precise rate of convergence to 0 …

Geochemistry And Inorganic Carbon Transport Of A Glacial Till Drumlin At A Road Salt Facility, Houbao Li

Open Access Dissertations

Investigations were conducted at a salt/premix storage facility lying on top of a glacial drumlin near the coastline in eastern Massachusetts, to characterize salt contaminated groundwater. Groundwater hydrogeochemical variations at different depths were determined based on ten years of monthly or quarterly water quality data from 54 monitoring wells. Groundwater was grouped in three water categories – shallow, middle and deep. Hydrogeochemical characterization indicates that the dominant water types are Na-Cl, Na-Ca-Cl and Ca-HCO3 from the shallow to deep water group. Rock weathering is the dominant hydrogeochemical process for deep water group, whereas salt water percolation and cation exchange control …

Semantically Grounded Learning From Unstructured Demonstrations, Scott D. Niekum

Open Access Dissertations

Robots exhibit flexible behavior largely in proportion to their degree of semantic knowledge about the world. Such knowledge is often meticulously hand-coded for a narrow class of tasks, limiting the scope of possible robot competencies. Thus, the primary limiting factor of robot capabilities is often not the physical attributes of the robot, but the limited time and skill of expert programmers. One way to deal with the vast number of situations and environments that robots face outside the laboratory is to provide users with simple methods for programming robots that do not require the skill of an expert.

For this …

Characterizing Distant Galaxies: Spectral Energy Distribution Analysis Of X-Ray Selected Star Forming Galaxies, Seth Pohatan Johnson

Open Access Dissertations

Comprehensive and robust analysis of galaxies found throughout cosmic time provides the means to probe the underlying characteristics of our Universe. Coupling observations and theory, spectral energy distribution (SED) fitting provides a method to derive the intrinsic properties of distant galaxies which then aid in defining galaxy populations and constraining current galaxy formation and evolution scenarios. One such population are the sub-millimeter galaxies (SMGs) whose high infrared luminosities -- typically associated with dust-obscured star formation -- and redshift distribution places them as likely key components in galaxy evolution. To fully analyze these systems, however, requires a near complete sampling of …

Martingale Central Limit Theorem And Nonuniformly Hyperbolic Systems, Luke Mohr

Open Access Dissertations

In this thesis we study the central limit theorem (CLT) for nonuniformly hyperbolic dynamical systems. We examine cases in which polynomial decay of correlations leads to a CLT with a non-standard scaling factor of √ n ln n. We also formulate an explicit expression for the the diffusion constant σ in situations where a return time function on the system is a certain class of supermartingale. We then demonstrate applications by exhibiting the CLT for the return time function in four classes of dynamical billiards, including one previously unproven case, the skewed stadium, as well as for the linked twist …

Reactive Heterocycles For Examining Polyketide Biosynthesis, Gitanjeli Prasad

Open Access Dissertations

Polyketides are a class of natural products that exhibit remarkable structural and functionally diversity and are highly sought after due to their medicinally important activities. For many decades now, polyketide synthases (PKSs), the mega-enzymes responsible for biosynthesis of polyketides have been the focus of extensive investigation to make new polyketides by polyketide engineering strategies. While there are many established methods to investigate polyketide enzymes and biosynthesis mechanisms, they have substantial shortcomings that have limited the extent of success with polyketide engineering efforts.

This thesis focuses on developing simple, flexible yet powerful tools for examining polyketide biosynthesis by overcoming some deficiencies …

O2 Activation And Allosteric Zn(Ii) Binding On Hif-Prolyl Hydroxylase-2 (Phd2), Serap Pektas

Open Access Dissertations

Oxygen homeostasis is essential to the life of aerobes, which is regulated in humans by Hypoxia Inducible Factor-1α (HIF-1α). Under hypoxic conditions, HIF-1α transactivates over a hundred genes related angiogenesis, erythropoiesis, etc. HIF-1α level and function is regulated by four HIF hydroxylase enzymes: three isoforms of prolyl hydroxylase domain (PHD1, PHD2 and PHD3) and factor inhibiting HIF-1α (FIH). PHD2 is the focus of this research. PHD2 is a non-heme Fe(II) 2-oxoglutarate dependent dioxygenase, which controls HIF-1α levels by hydroxylating two proline residues within the ODD domain of HIF-1α, then the hydroxylated prolines are recognized by pVHL, which targets HIF-1α for …

Optimizing Linear Queries Under Differential Privacy, Chao Li

Open Access Dissertations

Private data analysis on statistical data has been addressed by many recent literatures. The goal of such analysis is to measure statistical properties of a database without revealing information of individuals who participate in the database. Differential privacy is a rigorous privacy definition that protects individual information using output perturbation: a differentially private algorithm produces statistically indistinguishable outputs no matter whether the database contains a tuple corresponding to an individual or not.

It is straightforward to construct differentially private algorithms for many common tasks and there are published algorithms to support various tasks under differential privacy. However methods to design …

Transition Network: Exploring Intersections Between Culture, The Climate Crisis, And A Digital Network In A Community - Driven Global Social Movement, Emily Polk

Open Access Dissertations

The core aim of this research is to explore the communication processes of the Transition movement, a community-led global social movement as it adapted in a local context. The Transition movement facilitates community-led responses to the current global financial and climate crisis via the Transition Network, an online network that began in 2006, and is comprised of more than 2000 initiatives in 35 countries that have used the Transition model to start projects that use small-scale solutions to achieve greater sustainability. This research uses qualitative ethnographic methods and a theoretical framework based on actor network theory to better understand how …

Reconfigurable Technologies For Next Generation Internet And Cluster Computing, Deepak C. Unnikrishnan

Open Access Dissertations

Modern web applications are marked by distinct networking and computing characteristics. As applications evolve, they continue to operate over a large monolithic framework of networking and computing equipment built from general-purpose microprocessors and Application Specific Integrated Circuits (ASICs) that offers few architectural choices. This dissertation presents techniques to diversify the next-generation Internet infrastructure by integrating Field-programmable Gate Arrays (FPGAs), a class of reconfigurable integrated circuits, with general-purpose microprocessor-based techniques. Specifically, our solutions are demonstrated in the context of two applications - network virtualization and distributed cluster computing.

Network virtualization enables the physical network infrastructure to be shared among several …

Twisted Weyl Group Multiple Dirichlet Series Over The Rational Function Field, Holley Ann Friedlander

Open Access Dissertations

Let K be a global field. For each prime p of K, the p-part of a multiple Dirichlet series defined over K is a generating function in several variables for the p-power coefficients. Let _ be an irreducible, reduced root system, and let n be an integer greater than 1. Fix a prime power q 2 Z congruent to 1 modulo 2n, and let Fq(T) be the field of rational functions in T over the finite field Fq of order q. In this thesis, we examine the relationship between Weyl …

Replica Exchange Monte Carlo Simulations Of The Ising Spin Glass: Static And Dynamic Properties, Burcu Yucesoy

Open Access Dissertations

Spin glasses have been the subject of intense study and considerable controversy for decades, and the low-temperature phase of short-range spin glasses is still poorly understood. Our main goal is to improve our understanding in this area and find an answer to the following question: Are there only a single pair or a countable infinity of pure states in the low temperature phase of the EA spin glass? To that aim we first start by introducing spin glasses and provide a brief history of their research, then proceed to describe our method of simulation, the parallel tempering Monte Carlo algorithm. …

Properties Of Singular Schubert Varieties, Jennifer Koonz

Open Access Dissertations

This thesis deals with the study of Schubert varieties, which are subsets of flag varieties indexed by elements of Weyl groups. We start by defining Lascoux elements in the Hecke algebra, and showing that they coincide with the Kazhdan-Lusztig basis elements in certain cases. We then construct a resolution (Z_w, π) of the Schubert variety X_w for which Rπ_*(C[l(w)]) is a sheaf on X_w whose expression in the Hecke algebra is closely related to the Lascoux element. We also define two new polynomials which coincide with the intersection cohomology Poincar\'e polynomial in …

Resilient Environmental Governance: Protecting Changing Ecosystems Through Multilevel Governance, Casey Stevens

Open Access Dissertations

International governance is increasingly defined by multilevel governance; with short-term projects, transnational cooperation between different groups, and unclear institutional space. In this situation, a key issue is the resilience of governance arrangements or the ability of governance arrangements to respond to political and ecological shocks to the system. Using international biodiversity governance, this study explores the question: What social and political processes produce resilient governance?

This study argues that the key to understanding resilient governance is the network structure within and outside of the governance arrangement. Modular network structures are able to generate ideas from multiple sources, able to solve …

Uncertainty In Climatic Change Impacts On Multiscale Watershed Systems, Olga V. Tsvetkova

Open Access Dissertations

Uncertainty in climate change plays a major role in watershed systems. The increase in variability and intensity in temperature and precipitation affects hydrologic cycle in spatial and temporal dimensions. Predicting uncertainty in climate change impacts on watershed systems can help to understand future climate-induced risk on watershed systems and is essential for designing policies for mitigation and adaptation. Modeling the temporal patterns of uncertainties is assessed in the New England region for temperature and precipitation patterns over a long term. The regional uncertainty is modeled using Python scripting and GIS to analyze spatial patterns of climate change uncertainties over space …

Development Of Mass Spectrometry-Based Methods For Quantitation And Characterization Of Protein Drugs: Transferrin As A Model Drug Delivery Vehicle, Shunhai Wang

Open Access Dissertations

In the last two decades, protein drugs have enjoyed a rapid growth and achieved a tremendous success in treating human diseases. However, the presence of physiological barriers greatly impedes the efficient delivery of such unconventional large molecule drugs, and therefore limits their clinical utility. An elegant way to address this challenge takes advantage of certain endogenous transporter proteins, such as human transferrin (Tf), whose ability to traverse physiological barriers has been extensively exploited. However, methods to investigate Tf-based drug delivery remained insufficient and unsatisfactory until recent development of quantitative mass spectrometry (MS). Hereby, MS-based methods have been developed and validated …

Transiently Powered Computers, Benjamin Ransford

Open Access Dissertations

Demand for compact, easily deployable, energy-efficient computers has driven the development of general-purpose transiently powered computers (TPCs) that lack both batteries and wired power, operating exclusively on energy harvested from their surroundings.

TPCs' dependence solely on transient, harvested power offers several important design-time benefits. For example, omitting batteries saves board space and weight while obviating the need to make devices physically accessible for maintenance. However, transient power may provide an unpredictable supply of energy that makes operation difficult. A predictable energy supply is a key abstraction underlying most electronic designs. TPCs discard this abstraction in favor of opportunistic computation that …

Elastic Resource Management In Cloud Computing Platforms, Upendra Sharma

Open Access Dissertations

Large scale enterprise applications are known to observe dynamic workload; provisioning correct capacity for these applications remains an important and challenging problem. Predicting high variability fluctuations in workload or the peak workload is difficult; erroneous predictions often lead to under-utilized systems or in some situations cause temporarily outage of an otherwise well provisioned web-site. Consequently, rather than provisioning server capacity to handle infrequent peak workloads, an alternate approach of dynamically provisioning capacity on-the-fly in response to workload fluctuations has become popular.

Cloud platforms are particularly suited for such applications due to their ability to provision capacity when needed and charge …

Charge Transport Studies Of Proton And Ion Conducting Materials, Craig William Versek

Open Access Dissertations

The development of a high-throughput impedance spectroscopy instrumentation platform for conductivity characterization of ion transport materials is outlined. Collaborative studies using this system are summarized. Charge conduction mechanisms and conductivity data for small molecule proton conducting liquids, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, and select mixtures of these compounds are documented. Furthermore, proton diffusivity measurements using a Pulse Field Gradient Nuclear Magnetic Resonance (PFG NMR) technique for imidazole and 1,2,3-triazole binary mixtures are compared. Studies of azole functionalized discotic and linear mesogens with conductivity, structural, and thermal characterizations are detailed.

High-Performance Processing Of Continuous Uncertain Data, Thanh Thi Lac Tran

Open Access Dissertations

Uncertain data has arisen in a growing number of applications such as sensor networks, RFID systems, weather radar networks, and digital sky surveys. The fact that the raw data in these applications is often incomplete, imprecise and even misleading has two implications: (i) the raw data is not suitable for direct querying, (ii) feeding the uncertain data into existing systems produces results of unknown quality.

This thesis presents a system for uncertain data processing that has two key functionalities, (i) capturing and transforming raw noisy data to rich queriable tuples that carry attributes needed for query processing with quantified uncertainty, …

Exploiting Domain Structure In Multiagent Decision-Theoretic Planning And Reasoning, Akshat Kumar

Open Access Dissertations

This thesis focuses on decision-theoretic reasoning and planning problems that arise when a group of collaborative agents are tasked to achieve a goal that requires collective effort. The main contribution of this thesis is the development of effective, scalable and quality-bounded computational approaches for multiagent planning and coordination under uncertainty. This is achieved by a synthesis of techniques from multiple areas of artificial intelligence, machine learning and operations research. Empirically, each algorithmic contribution has been tested rigorously on common benchmark problems and, in many cases, real-world applications from machine learning and operations research literature.

The first part of the thesis …

A Non-Asymptotic Approach To The Analysis Of Communication Networks: From Error Correcting Codes To Network Properties, Ali Eslami

Open Access Dissertations

This dissertation has its focus on two different topics: 1. non-asymptotic analysis of polar codes as a new paradigm in error correcting codes with very promising features, and 2. network properties for wireless networks of practical size. In its first part, we investigate properties of polar codes that can be potentially useful in real-world applications. We start with analyzing the performance of finite-length polar codes over the binary erasure channel (BEC), while assuming belief propagation (BP) as the decoding method. We provide a stopping set analysis for the factor graph of polar codes, where we find the size of the …