Spontaneous Parametric Down Conversion Of Photons Through Β-Barium Borate, 2016 California Polytechnic State University, San Luis Obispo
Spontaneous Parametric Down Conversion Of Photons Through Β-Barium Borate, Luke Horowitz
An apparatus for detecting pairs of entangled 405nm photons that have undergone Spontaneous Parametric Down Conversion through β-Barium Borate is described. By using avalanche photo-diodes to detect the low-intensity converted beam and a coincidence module to register coincident photons, it is possible to create an apparatus than can be used to perform quantum information experiments under a budget appropriate for an undergraduate physics lab.
Memory As Bayesian Inference: On The Connection Between Memory And The Second Law Of Thermodynamics, 2016 College of William and Mary
Memory As Bayesian Inference: On The Connection Between Memory And The Second Law Of Thermodynamics, Wade Daniel Hodson
Undergraduate Honors Theses
A recent theoretical paper by Leonard Mlodinow and Todd Brun suggests that the functioning of physical records or "memories" is never accompanied by a decrease in entropy, meaning that all memories "align" with the thermodynamic arrow of time. In this thesis, we characterize a class of physical systems as memories in terms of inferences that can be made about the state of the world, given certain information about these systems. Tools from Bayesian probability theory are used to quantify the informativeness and reliability associated with such inferences. Based on consideration of two model systems, one classical and one quantum, we ...
Simulation Of Heterogeneous Colloidal Particles Immersed In Liquid Crystals, 2016 The University of Western Ontario
Simulation Of Heterogeneous Colloidal Particles Immersed In Liquid Crystals, Setarehalsadat Changizrezaei
Electronic Thesis and Dissertation Repository
This thesis describes an investigation of interactions between colloidal particles immersed in a liquid crystal. The presence of colloidal particles in the liquid crystal distorts the director field distorted from its uniform orientation. These elastic distortions produce topological defects around the particles, which induce anisotropic interactions between them, and these anisotropic interactions can be used to manufacture non-closed packed colloidal crystals, such as diamond lattices, which are interesting in photonic applications. First, different types of liquid crystals, the mathematical tools to describe the anisotropic nature of liquid crystals, the Landau-de Gennes free-energy model to investigate the particle’s interaction, and ...
Statistical Biophysics Blog: So You Want To Do Some Path Sampling …, 2016 Oregon Health & Science University
Statistical Biophysics Blog: So You Want To Do Some Path Sampling …, Daniel M. Zuckerman
Basic concepts and limitations of path sampling are described.
Turbulent Transport With Intermittency: Expectation Of A Scalar Concentration, 2016 Ecole Normale Superieure de Lyon
Turbulent Transport With Intermittency: Expectation Of A Scalar Concentration, Mark P. Rast, Jean-Francois Pinton, P. D. Mininni
Astrophysical & Planetary Sciences Faculty Contributions
Scalar transport by turbulent flows is best described in terms of Lagrangian parcel motions. Here we measure the Eulerian distance travel along Lagrangian trajectories in a simple point vortex flow to determine the probabilistic impulse response function for scalar transport in the absence of molecular diffusion. As expected, the mean squared Eulerian displacement scales ballistically at very short times and diffusively for very long times, with the displacement distribution at any given time approximating that of a random walk. However, significant deviations in the displacement distributions from Rayleigh are found. The probability of long distance transport is reduced over inertial ...
High-Temperature Asymptotics Of Orthogonal Mean-Field Spin Glasses, 2016 University of Pennsylvania
High-Temperature Asymptotics Of Orthogonal Mean-Field Spin Glasses, Bhaswar B. Bhattacharya, Subhabrata Sen
We evaluate the high temperature limit of the free energy of spin glasses on the hypercube with Hamiltonian HN(σ) = σTJσ, where the coupling matrix J is drawn from certain symmetric orthogonally invariant ensembles. Our derivation relates the annealed free energy of these models to a spherical integral, and expresses the limit of the free energy in terms of the limiting spectral measure of the coupling matrix J. As an application, we derive the limiting free energy of the random orthogonal model at high temperatures, which confirms non-rigorous calculations of Marinari et al. (J Phys A ...
The Global Stability Of The Solution To The Morse Potential In A Catastrophic Regime, 2016 Harvey Mudd College
The Global Stability Of The Solution To The Morse Potential In A Catastrophic Regime, Weerapat Pittayakanchit
HMC Senior Theses
Swarms of animals exhibit aggregations whose behavior is a challenge for mathematicians to understand. We analyze this behavior numerically and analytically by using the pairwise interaction model known as the Morse potential. Our goal is to prove the global stability of the candidate local minimizer in 1D found in A Primer of Swarm Equilibria. Using the calculus of variations and eigenvalues analysis, we conclude that the candidate local minimizer is a global minimum with respect to all solution smaller than its support. In addition, we manage to extend the global stability condition to any solutions whose support has a single ...
Structure Of Sheared And Rotating Turbulence: Multiscale Statistics Of Lagrangian And Eulerian Accelerations And Passive Scalar Dynamics, Frank G. Jacobitz, Kai Schneider, Wouter J. T. Bos, Marie Farge
School of Engineering: Faculty Scholarship
The acceleration statistics of sheared and rotating homogeneous turbulence are studied using direct numerical simulation results. The statistical properties of Lagrangian and Eulerian accelerations are considered together with the influence of the rotation to shear ratio, as well as the scale dependence of their statistics. The probability density functions (pdfs) of both Lagrangian and Eulerian accelerations show a strong and similar dependence on the rotation to shear ratio. The variance and flatness of both accelerations are analyzed and the extreme values of the Eulerian acceleration are observed to be above those of the Lagrangian acceleration. For strong rotation it is ...
Monte Carlo Studies Of Underconstrained Magnetism In Ultracold Fermionic Alkaline Earth Atomic Gases, 2016 University of Colorado, Boulder
Monte Carlo Studies Of Underconstrained Magnetism In Ultracold Fermionic Alkaline Earth Atomic Gases, Pavao Santak
Undergraduate Honors Theses
Physicists have been trying to create artificial magnetic systems using ultra-cold atomic gases as their simulators. However, behavior of many ultra-cold atomic systems is not very well understood yet. Ultra-cold fermionic alkaline earth atomic (AEA) gases are one of those systems. In this thesis, we study the effects of thermal fluctuations on the overall macroscopic behavior of ultra-cold fermionic AEA gases using a particular semiclassical model. We study the AEA systems on a square lattice with periodic boundary conditions. To investigate the behavior of AEA systems under the effects of thermal fluctuations, we analyze several different types of correlation functions ...
Hydrodynamic Interactions And Collective Dynamics Of Multiple Inclusions In Two-Dimensional Membranes, 2016 University of Colorado Boulder
Hydrodynamic Interactions And Collective Dynamics Of Multiple Inclusions In Two-Dimensional Membranes, Kaitlyn A. Parsons
Undergraduate Honors Theses
The hydrodynamics of multiple inclusions in two-dimensional, thin films of smectic liquid crystal material are studied. The self-mobilities of these inclusions are experimentally studied in highly crowded conditions by analyzing their Brownian motion. Saffman and Delbruck found the characteristic length, known as the Saffman length, beyond which momentum in a two-dimensional film has a negligible effect on an inclusion which is proportional to the thickness of the film. The effects of crowding are studied by varying the number of the nearest neighboring inclusions within one Saffman length. The self-mobilities of these inclusions are also experimentally studied for two islands of ...
Characterizing The Dynamic Properties Of Toron-Umbilic Pairs, 2016 University of Colorado Boulder
Characterizing The Dynamic Properties Of Toron-Umbilic Pairs, Timothy J. Boyle
Undergraduate Honors Theses
Topological defects are studied in many different fields of physics and have recently attracted the attention of researchers due to the interesting applications they provide. Liquid crystals, classified as a mesophase, provide a model experimental system for discovering the physics governing these defects. The research presented in this thesis characterizes the dynamic properties of defect ensembles dubbed “toron-umbilic pairs” and unveils the mechanisms behind their motion. Two different manifestations of motion were observed and are described by their relationships to the systems’ parameters and by the interactions exhibited by the defects themselves.
Active 2d Microrheological Studies In Freely-Suspended Smectic Liquid Crystal Films, 2016 University of Colorado Boulder
Active 2d Microrheological Studies In Freely-Suspended Smectic Liquid Crystal Films, Kyle R. Ferguson
Undergraduate Honors Theses
Thin, freely-suspended smectic liquid crystal films, due to their layered structure, provide an ideal system with which to study two dimensional (2D) hydrodynamics. We have performed some of the first experimental visualizations of actively-driven 2D flow fields, and compared these flow fields to predictions made by theoretical models. First, an experiment testing the flow field generated by a disk-shaped inclusion moving laterally in a film is described. Then an experiment testing the flow field generated by a thin nozzle injecting fluid at a quick rate into a large reservoir is detailed. Results are consistent with the idea that 2D fluids ...
Morphological And Material Effects In Van Der Waals Interactions, 2016 University of Massachusetts Amherst
Morphological And Material Effects In Van Der Waals Interactions, Jaime C. Hopkins
Van der Waals (vdW) interactions influence a variety of mesoscale phenomena, such as surface adhesion, friction, and colloid stability, and play increasingly important roles as science seeks to design systems on increasingly smaller length scales. Using the full Lifshitz continuum formulation, this thesis investigates the effects of system materials, shapes, and configurations and presents open-source software to accurately calculate vdW interactions.
In the Lifshitz formulation, the microscopic composition of a material is represented by its bulk dielectric response. Small changes in a dielectric response can result in substantial variations in the strength of vdW interactions. However, the relationship between these ...
Designing Active Granular Squares, 2016 University of Massachusetts Amherst
Designing Active Granular Squares, Christopher C. Olson
The goal of this thesis has been to find a means of i) designing an active square particle, and ii) continuously varying its degree of activity with the objective of understanding the effects of activity on the various phases of granular matter. The motivations, results and limitations of our methods of creating active particles are discussed in this thesis. The applicability of a stochastic model based on the Langevin equation in 2D as well as implications for future experiments are also discussed.
X-Ray Characterization Of Mesophases And Phase Transitions Of Dna Analogues In Solutions, 2016 University of Massachusetts Amherst
X-Ray Characterization Of Mesophases And Phase Transitions Of Dna Analogues In Solutions, Mustafa Selcuk Yasar
We think of DNA as double-stranded helices (duplex), but the polymer exists in many conformations. Several triplex and quadruplex DNA structures can be formed in laboratory settings and exist in nature. This thesis first provides a brief description of the nature of the order in arrays of duplex DNA under biologically relevant molecular crowding conditions. Then we compare the duplex DNA mesophases with the corresponding liquid crystalline phase behavior of the triplex and quadruplex DNA analogues. In particular, we focus on G-quadruplexes.
Observed in the folds of guanine-rich oligonucleotides, G-quadruplex structures are based on G-quartets formed by hydrogen bonding and ...
Event Generator Tunes Obtained From Underlying Event And Multiparton Scattering Measurements, Cms Collaboration, Ekaterina Cms Avdeeva, Kenneth A. Bloom, S. Bose, Daniel Claes, Aaron Dominguez, Caleb Fangmeier, Rebeca Gonzalez Suarez, Rami Kamalieddin, J. Keller, D. Knowlton, Ilya Kravchenko, F. Meier, Jose Monroy, F. Ratnikov, J. E. Siado, Gregory Snow
Kenneth Bloom Publications
New sets of parameters (“tunes”) for the underlying-event (UE) modelling of the PYTHIA8, PYTHIA6 and HERWIG++ MonteCarlo event generators are constructed using different parton distribution functions. Combined fits to CMS UE proton–proton (pp) data at √s = 7 TeV and to UE proton–antiproton (pp) data from the CDF experiment at lower √s, are used to study the UE models and constrain their parameters, providing thereby improved predictions for proton–proton collisions at 13 TeV. In addition, it is investigated whether the values of the parameters obtained from fits to UE observables are consistent with the values determined from fitting ...
Postural Responses To Perturbations Of The Vestibular System During Walking In Healthy Young And Older Adults, 2015 University of Nebraska Medical Center
Postural Responses To Perturbations Of The Vestibular System During Walking In Healthy Young And Older Adults, Jung Hung Chien
Theses & Dissertations
It has been shown that approximate one-third of US adults aged 40 years and older (69 million US citizens) have some type of vestibular problems. These declining abilities of the vestibular system affect quality of life. Difficulties in performing daily activities (dressing, bathing, getting in and out of the bed and etc.) have been highly correlated to loss of balance due to vestibular disorders. The exact number of people affected by vestibular disorders is still difficult to quantify. This might be because symptoms are difficult to describe and differences exist in the qualifying criteria within and across studies. Thus, it ...
The Effect Of Composition And Architecture On Polymer Behavior In Homopolymer Blends And Inter-Filament Bonding In 3d Printed Models, 2015 University of Tennessee - Knoxville
The Effect Of Composition And Architecture On Polymer Behavior In Homopolymer Blends And Inter-Filament Bonding In 3d Printed Models, Edward Roy Duranty
This dissertation presents work that increases our understanding of the effects of composition and architecture on copolymer structure and dynamics and how they affect material diffusion between filaments in a 3D printed model. Copolymers are polymer chains made up of at least two different monomers. The ordering and arrangement of the two monomer species within a copolymer can have drastic effects on the behavior and properties of the copolymer.
The first chapter of this dissertation examines how the copolymer composition affects the structure and dynamics of the chain in a homopolymer blend. This study used a modified Monte Carlo BFM ...
Statistical Biophysics Blog: Faq On Trajectory Ensembles, 2015 Oregon Health & Science University
Statistical Biophysics Blog: Faq On Trajectory Ensembles, Daniel M. Zuckerman
The basics of trajectories and the different types of trajectory ensembles are explained.
Distributions Of Long-Lived Radioactive Nuclei Provided By Star-Forming Environments, 2015 Xavier University - Cincinnati
Distributions Of Long-Lived Radioactive Nuclei Provided By Star-Forming Environments, Marco Fatuzzo, Fred Adams
Radioactive nuclei play an important role in planetary evolution by providing an internal heat source, which affects planetary structure and helps facilitate plate tectonics. A minimum level of nuclear activity is thought to be necessary—but not sufficient—for planets to be habitable. Extending previous work that focused on short-lived nuclei, this paper considers the delivery of long-lived radioactive nuclei to circumstellar disks in star forming regions. Although the long-lived nuclear species are always present, their abundances can be enhanced through multiple mechanisms. Most stars form in embedded cluster environments, so that disks can be enriched directly by intercepting ejecta ...