Physical Sciences and Mathematics Commons^™

Discrete Breathers At The Interface Between A Diatomic And A Monoatomic Granular Chain, C. Hoogeboom, G. Theocharis, Panos Kevrekidis

Panos Kevrekidis

In the present work, we develop a systematic examination of the existence, stability, and dynamical properties of a discrete breather at the interface between a diatomic and a monoatomic granular chain. We remarkably find that such an “interface breather” is more robust than its bulk diatomic counterpart throughout the gap of the linear spectrum. The latter linear spectral gap needs to exist for the breather state to arise and the relevant spectral conditions are discussed. We illustrate the minimal excitation conditions under which such an interface breather can be “nucleated” and analyze its apparently weak interaction with regular highly nonlinear …

Discovering Issue-Based Voting Groups Within The Us Senate, Rachel Shorey, Andrew Mccallum, Hanna Wallach

Andrew McCallum

Members of the US Senate cast votes on a wide array of issues. Understanding a senator's position on an issue is important to constituents, sources of campaign funding, and groups seeking to persuade senators or build consensus. Classifying senators' positions often falls into the hands of interest groups. Many lobbyists and issue-based organizations give senators scores based on the number of times senators vote in accordance with the organization's ideals. Organization staff must choose which bills to consider and then investigate their content manually. To produce more objective and replicable rankings, political scientists have developed statistical models to group and …

Symbiogenesis. A New Principle Of Evolution Rediscovery Of Boris Mikhaylovich Kozo-Polyansky (1890–1957), Lynn Margulis

Lynn Margulis (1938 - 2011)

The following is a heavily edited transcript of my illustrated lecture, that included our 14 minute video (with a 2 minute animation model) that shows each step in live organisms hypothesized in the origin of nucleated cells from bacteria (“eukaryosis”). New observations presented with modern examples of live phenomena make us virtually certain that B.M. Kozo-Polyansky’s “new principle” (1924) of the importance of symbiogenesis in the evolutionary process of at least 2000 million years of life on Earth is correct. The widely touted but undocumented explanation of the origin of evolutionary novelty by “gradual accumulation of random mutations” will be …

Comment On “Direct Mapping Of The Finite Tem- Perature Phase Diagram Of Strongly Correlated Quantum Models”, L Pollet, N Prokof’Ev, B Svistunov

Nikolai Prokof'ev

In their Letter, Zhou, Kato, Kawashima, and Trivedi claim that finite-temperature critical points of strongly correlated quantum models emulated by optical lattice experiments can generically be deduced from kinks in the derivative of the density profile of atoms in the trap with respect to the external potential, $\kappa = -dn(r)/dV(r)$. In this comment we demonstrate that the authors failed to achieve their goal: to show that under realistic experimental conditions critical densities $n_c(T,U)$ can be extracted from density profiles with controllable accuracy.

Exploring The Use Of Numerical Relativity Waveforms In Burst Analysis Of Precessing Black Hole Mergers, Sebastian Fischetti, James Healy, Laura Cadonati, Lionel London, Satyanarayan R.P. Mohapatra, Deirdre Shoemaker

Laura Cadonati

Recent years have witnessed tremendous progress in numerical relativity and an ever improving performance of ground-based interferometric gravitational wave detectors. In preparation for Advanced LIGO and a new era in gravitational wave astronomy, the numerical relativity and gravitational wave data analysis communities are collaborating to ascertain the most useful role for numerical relativity waveforms in the detection and characterization of binary black hole coalescences. In this paper, we explore the detectability of equal mass, merging black hole binaries with precessing spins and total mass M_T in [80,350]Msol, using numerical relativity waveforms and template-less search algorithms designed for gravitational wave bursts. …

Gloucester Marine Station: Future Development Feasibility Study, Jack F. Ahern, Ben Eli Webb

Landscape Architecture & Regional Planning Studio and Student Research and Creative Activity

The study commenced in July 2009 with historical research about the site and its context, site analysis, including the existing conditions and development regulations. This analysis included: topography, soils, vegetation, structures, utilities, easements, property deed, and city, state, and federal regulations. From this analysis an assessment of future development potentials was made based on the existing data/documents from UMass files, public records, Mass GIS data, site visits, and interviews with Gloucester, Commonwealth of Massachusetts, and other officials and stakeholders. From the assessment we identified potential future uses, building locations, and feasible alternative layouts of the site. These alternatives were summarily …

Compactons In Nonlinear Schrödinger Lattices With Strong Nonlinearity Management, F. Kh. Abdullaev, Panos Kevrekidis, M. Salerno

Panos Kevrekidis

The existence of compactons in the discrete nonlinear Schr\"odinger equation in the presence of fast periodic time modulations of the nonlinearity is demonstrated. In the averaged DNLS equation the resulting effective inter-well tunneling depends on modulation parameters {\it and} on the field amplitude. This introduces nonlinear dispersion in the system and can lead to a prototypical realization of single- or multi-site stable discrete compactons in nonlinear optical waveguide and BEC arrays. These structures can dynamically arise out of Gaussian or compactly supported initial data.

Vibrational Spectroscopy Of Intermediates Of C-H Bond Activation By Transition Metal Oxide Cations, Gokhan Altinay

Open Access Dissertations

Direct, efficient oxidation of alkanes is a long-standing goal of catalysis. Gas phase FeO+ can convert methane to methanol and benzene to phenol under thermal conditions. Two key intermediates of these reactions are the [HO-Fe-R]+ insertion intermediate and Fe+(ROH) (R=CH3 or C6H5) exit channel complex. This work describes measurements of the vibrational spectra of these intermediates and electronic structure theory calculations of the potential energy surfaces for the reactions. They help to characterize the mechanism for these reactions. Chapter 1 describes previous studies of methane-to-methanol and benzene-to-phenol conversion by gas-phase transition metal oxide cations. Spectra of gas-phase reaction intermediates are …

Geometry Of Satake And Toroidal Compactifications, Patrick Michael Boland

Open Access Dissertations

In [JM02, section 14], Ji and MacPherson give new constructions of the Borel--Serre and reductive Borel--Serre compactifications [BS73, Zuc82] of a locally symmetric space. They use equivalence classes of eventually distance minimizing (EDM) rays to describe the boundaries of these compactications. The primary goal of this thesis is to construct the Satake compactifications of a locally symmetric space [Sat60a] using finer equivalence relations on EDM rays. To do this, we first construct the Satake compactifications of the global symmetric space [Sat60b] with equivalence classes of geodesics in the symmetric space. We then define equivalence relations on EDM rays using geometric …

Increasing Scalability In Algorithms For Centralized And Decentralized Partially Observable Markov Decision Processes: Efficient Decision-Making And Coordination In Uncertain Environments, Christopher Amato

Open Access Dissertations

As agents are built for ever more complex environments, methods that consider the uncertainty in the system have strong advantages. This uncertainty is common in domains such as robot navigation, medical diagnosis and treatment, inventory management, sensor networks and e-commerce. When a single decision maker is present, the partially observable Markov decision process (POMDP) model is a popular and powerful choice. When choices are made in a decentralized manner by a set of decision makers, the problem can be modeled as a decentralized partially observable Markov decision process (DEC-POMDP). While POMDPs and DEC-POMDPs offer rich frameworks for sequential decision making …

A Geometric Framework For Transfer Learning Using Manifold Alignment, Chang Wang

Open Access Dissertations

Many machine learning problems involve dealing with a large amount of high-dimensional data across diverse domains. In addition, annotating or labeling the data is expensive as it involves significant human effort. This dissertation explores a joint solution to both these problems by exploiting the property that high-dimensional data in real-world application domains often lies on a lower-dimensional structure, whose geometry can be modeled as a graph or manifold. In particular, we propose a set of novel manifold-alignment based approaches for transfer learning. The proposed approaches transfer knowledge across different domains by finding low-dimensional embeddings of the datasets to a common …

Frontiers In Theoretical High Energy Physics: From Physics Beyond The Standard Model To Cosmology, Mohamed M. Anber

Open Access Dissertations

This dissertation is focused on three lines of work. In the first part, we consider aspects of holography and gauge/gravity duality in lower and higher dimensions. In particular, we study the duality for exact solutions localized on the Randal-Sundrum 2-branes. We also test if some holographic principles in general relativity can be generalized to include higher derivative theories of gravity; namely Lovelock gravity. In the second part we consider the role of pseudo Nambu-Goldstone bosons (pNGBs) in inflationary cosmology. Specifically, we construct an inflationary model using string theory axions, and use these pNGBs to produce the observed coherent magnetic field …

Bounds On Service Quality For Networks Subject To Augmentation And Attack, George Dean Bissias

Open Access Dissertations

Assessing a network's vulnerability to attack and random failure is a difficult and important problem that changes with network application and representation. We furnish algorithms that bound the robustness of a network under attack. We utilize both static graph-based and dynamic trace-driven representations to construct solutions appropriate for different scenarios. For static graphs we first introduce a spectral technique for developing a lower bound on the number of connected pairs of vertices in a graph after edge removal, which we apply to random graphs and the power grid of the Philippines. To address the problem of resource availability in networks …

Charge And Energy Transport In Single Quantum Dot/Organic Hybrid Nanostructures, Kevin Thomas Early

Open Access Dissertations

Hybrid quantum dot /organic semiconductor systems are of great interest in optoelectronic and photovoltaic applications, because they combine the robust and tunable optical properties of inorganic semiconductors with the processability of organic thin films. In particular, cadmium selenide (CdSe) quantum dots coordinated with oligo-(phenylene vinylene) ligands have displayed a number of hybrid optical properties that make them particularly well-suited to these applications. When probed on an individual particle level, these so-called CdSe-OPV nanostructures display a number of surprising photophysical characteristics, including strong quenching of fluorescence from coordinating ligands, enhanced emission from the CdSe quantum dot core, suppression of fluorescence intermittency, …

Self-Assembly Of Nanoparticles At Liquid-Liquid Interfaces, Kan Du

Open Access Dissertations

In this thesis, we studied the self-assembly of nanoparticles at liquid metal-water interfaces and oil-water interfaces. We demonstrated a simple approach to form nanostructured electronic devices by self-assembly of nanoparticles at liquid metal surfaces. In this approach, two liquid-metal droplets, which were coated with a monolayer of ligand-stabilized nanoparticles, were brought into contact. They did not coalesce but instead remained separated by the nanoparticles assembled at the interface. Devices formed by this method showed electron transport between droplets that was characteristic of the Coulomb blockade, where current was suppressed below a tunable threshold voltage because of the energy of charging …

A Hierarchical Spherical Radial Quadrature Algorithm For Multilevel Glmms, Gsmms, And Gene Pathway Analysis, Jacob A. Gagnon

Open Access Dissertations

The first part of my thesis is concerned with estimation for longitudinal data using generalized semi-parametric mixed models and multilevel generalized linear mixed models for a binary response. Likelihood based inferences are hindered by the lack of a closed form representation. Consequently, various integration approaches have been proposed. We propose a spherical radial integration based approach that takes advantage of the hierarchical structure of the data, which we call the 2 SR method. Compared to Pinheiro and Chao's multilevel Adaptive Gaussian quadrature, our proposed method has an improved time complexity with the number of functional evaluations scaling linearly in the …

Using Context To Enhance The Understanding Of Face Images, Vidit Jain

Open Access Dissertations

Faces are special objects of interest. Developing automated systems for detecting and recognizing faces is useful in a variety of application domains including providing aid to visually-impaired people and managing large-scale collections of images. Humans have a remarkable ability to detect and identify faces in an image, but related automated systems perform poorly in real-world scenarios, particularly on faces that are difficult to detect and recognize. Why are humans so good? There is general agreement in the cognitive science community that the human brain uses the context of the scene shown in an image to solve the difficult cases of …

Data Management And Wireless Transport For Large Scale Sensor Networks, Ming Li

Open Access Dissertations

Today many large scale sensor networks have emerged, which span many different sensing applications. Each of these sensor networks often consists of millions of sensors collecting data and supports thousands of users with diverse data needs. Between users and wireless sensors there are often a group of powerful servers that collect and process data from sensors and answer users' requests. To build such a large scale sensor network, we have to answer two fundamental research problems: i) what data to transmit from sensors to servers? ii) how to transmit the data over wireless links? Wireless sensors often can not transmit …

Analysis Of The Gouldsboro Pluton And The Fehr Granite: Understanding The Scales Of Magmatic Processes And Partial Melt Generation From The Deep To Shallow Crust, George Christopher Koteas

Open Access Dissertations

The heterogeneity of the continental crust has a first order control on the dynamics of plate tectonic processes and the compositions of the Earth in both time and space. Heterogeneity can be characterized at a variety of scales and in a multitude of tectonic environments, but it is the links between seemingly disparate tectonic settings and crustal levels that are critical in understanding construction of the continents. The focus of this dissertation work is to apply microtextural, microgeochemical, whole rock geochemical and traditional petrographic techniques to study features in both deep and shallow crustal igneous rocks. The goal of these …

Optimization-Based Approximate Dynamic Programming, Marek Petrik

Open Access Dissertations

Reinforcement learning algorithms hold promise in many complex domains, such as resource management and planning under uncertainty. Most reinforcement learning algorithms are iterative - they successively approximate the solution based on a set of samples and features. Although these iterative algorithms can achieve impressive results in some domains, they are not sufficiently reliable for wide applicability; they often require extensive parameter tweaking to work well and provide only weak guarantees of solution quality. Some of the most interesting reinforcement learning algorithms are based on approximate dynamic programming (ADP). ADP, also known as value function approximation, approximates the value of being …

Field Portable Methods For The Determination Of Arsenic In Environmental Samples, James Kalman Kearns

Open Access Dissertations

Arsenic contamination of the environment is a worldwide health hazard. This research project focused on four areas: development and testing of low cost, field portable devices capable of measuring levels of arsenic at 10 μg L-1 or less; specific chemical techniques for such testing; creation of educational tools and techniques to allow operators who lack advanced chemistry training to perform accurate testing; and the determination and use of a biomarker in DNA as a cancer predictor in individuals exposed to environmental arsenic. The analytical techniques explored include: (1) the Gutzeit method of arsenic determination though arsine gas production, which was …

Time Resolved Single Molecule Spectroscopy Of Semiconductor Quantum Dot/Conjugated Organic Hybrid Nanostructures, Michael Yemoh Odoi

Open Access Dissertations

Single molecule studies on CdSe quantum dots functionalized with oligo-phenylene vinylene ligands (CdSe-OPV) provide evidence of strong electronic communication that facilitate charge and energy transport between the OPV ligands and the CdSe quantum dot core. This electronic interaction greatly modify, the photoluminescence properties of both bulk and single CdSe-OPV nanostructure thin film samples. Size-correlated wide-field fluorescence imaging show that blinking suppression in single CdSe-OPV is linked to the degree of OPV coverage (inferred from AFM height scans) on the quantum dot surface. The effect of the complex electronic environment presented by photoexcited OPV ligands on the excited state property of …

System Support For Perpetual Mobile Tracking, Jacob Sorber

Open Access Dissertations

Recent advances in low-power electronics, energy harvesting, and sensor technologies are poised to revolutionize mobile and embedded computing, by enabling networks of mobile sensor devices that are long-lived and self-managing. When realized, this new generation of perpetual systems will have a far-reaching and transformative impact, improving scientists’ ability to observe natural phenomena, and enabling many ubiquitous computing applications for which regular maintenance is not feasible. In spite of these benefits, perpetual systems face many programming and deployment challenges. Conditions at runtime are unknown and highly variable. Variations in harvested energy and energy consumption, as well as mobility-induced changes in network …

Structural Characterization Of The Pre-Amyloid Oligomers Of Β-2-Microglobulin Using Covalent Labeling And Mass Spectrometry, Vanessa Leah Castillo Mendoza

Open Access Dissertations

The initial steps involved in the assembly of normally soluble proteins into amyloid fibrils remain unclear, yet over 20 human diseases are associated with proteins that aggregate in this manner. Protein surface modification is a potential means of mapping the interaction sites in early oligomers that precede amyloid formation. This dissertation focuses on the use of covalent labeling combined with mass spectrometry to elucidate the structural features of Cu(II)-induced β-2-microglobulin (β2m) amyloid formation. An improved covalent modification and MS-based approach for protein surface mapping has been developed to address the need for a reliable approach that ensures protein structural integrity …

Problems In Generic Combinatorial Rigidity: Sparsity, Sliders, And Emergence Of Components, Louis Simon Theran

Open Access Dissertations

Rigidity theory deals in problems of the following form: given a structure defined by geometric constraints on a set of objects, what information about its geometric behavior is implied by the underlying combinatorial structure. The most well-studied class of structures is the bar-joint framework, which is made of fixed-length bars connected by universal joints with full rotational degrees of freedom; the allowed motions preserve the lengths and connectivity of the bars, and a framework is rigid if the only allowed motions are trivial motions of Euclidean space. A remarkable theorem of Maxwell-Laman says that rigidity of generic bar-joint frameworks depends …

Enabling Accurate Analysis Of Private Network Data, Michael Hay

Open Access Dissertations

This dissertation addresses the challenge of enabling accurate analysis of network data while ensuring the protection of network participants' privacy. This is an important problem: massive amounts of data are being collected (facebook activity, email correspondence, cell phone records), there is huge interest in analyzing the data, but the data is not being shared due to concerns about privacy. Despite much research in privacy-preserving data analysis, existing technologies fail to provide a solution because they were designed for tables, not networks, and cannot be easily adapted to handle the complexities of network data. We develop several technologies that advance us …

Characterization And Interactions Of Ultrafast Surface Plasmon Pulses, Sibel Ebru Yalcin

Open Access Dissertations

Surface Plasmon Polaritons (SPPs) are considered to be attractive components for plasmonics and nanophotonic devices due to their sensitivity to interface changes, and their ability to guide and confine light beyond the diffraction limit. They have been utilized in SPP resonance sensors and near field imaging techniques and, more recently, SPP experiments to monitor and control ultrafast charge carrier and energy relaxation dynamics in thin films. In this thesis, we discuss excitation and propagation properties of ultrafast SPPs on thin extended metal films and SPP waveguide structures. In addition, localized and propagating surface plasmon interactions in functional plasmonic nanostructures will …

Wrinkling Of Floating Thin Polymer Films, Jiangshui Huang

Doctoral Dissertations 1896 - February 2014

This thesis presents an extensive study of wrinkling of thin polystyrene films, tens of nanometers in thickness, floating on the surface of water or water modified with surfactant.

First, we study the wrinkling of floating thin polystyrene films under a capillary force exerted by a drop of water placed on its surface. The wrinkling pattern is characterized by the number and length of wrinkles. A metrology for measuring the elasticity and thickness of ultrathin films is constructed by combining the scaling relations that are developed for the length of the wrinkles with those for the number of wrinkles. This metrology …

Torsion In The Cohomology Of Congruence Subgroups Of Sl (4. Z) And Galois Representations, Avner Ash, Paul E. Gunnells, Mark Mcconnell

Paul Gunnells

We report on the computation of torsion in certain homology theories of congruence subgroups of SL(4,Z). Among these are the usual group cohomology, the Tate–Farrell cohomology, and the homology of the sharbly complex. All of these theories yield Hecke modules. We conjecture that the Hecke eigenclasses in these theories have attached Galois representations. The interpretation of our computations at the torsion primes 2, 3, 5 is explained. We provide evidence for our conjecture in the 15 cases of odd torsion that we found in levels ⩽31.

Type-1.5 Superconducting State From An Intrinsic Proximity Effect In Two-Band Superconductors, Egor Babaev, Johan Carlstrom, Martin Speight

Egor Babaev

We show that in multiband superconductors, even an extremely small interband proximity effect can lead to a qualitative change in the interaction potential between superconducting vortices by producing long-range intervortex attraction. This type of vortex interaction results in an unusual response to low magnetic fields leading to phase separation into domains of two-component Meissner states and vortex droplets.