Physical Sciences and Mathematics Commons^™

Projectile Interactions In Granular Impact Cratering, E. L. Nelson, Hiroaki Katsuragi, Patrick Mayor, Douglas J. Durian

Douglas J. Durian

We present evidence for the interactions between a ball and the container boundaries, as well as between two balls, that are mediated by the granular medium during impact cratering. The presence of the bottom boundary affects the final penetration depth only for low drop heights with shallow filling, in which case, surprisingly, the penetration becomes deeper. By contrast the presence of the sidewall causes less penetration and also an effective repulsion. Repulsion is also found for two balls dropped side by side.

Avalanche Statistics And Time-Resolved Grain Dynamics For A Driven Heap, Adam Ross Abate, Hiroaki Katsuragi, Douglas J. Durian

Douglas J. Durian

We probe the dynamics of intermittent avalanches caused by steady addition of grains to a quasi-twodimensional heap. To characterize the time-dependent average avalanche flow speed v(t), we image the top free surface. To characterize the grain fluctuation speed δv(t), we use speckle-visibility spectroscopy. During an avalanche, we find that the fluctuation speed is approximately one-tenth the average flow speed, δv ≈ 0.1v, and that these speeds are largest near the beginning of an event. We also find that the distribution of event durations is peaked, and that event sizes are correlated with the time interval since the end of the …

Constructing Explicit Magnetic Analogies For The Dynamics Of Glass Forming Liquids, Jacob D. Stevenson, Aleksandra M. Walczak, Randall W. Hall, Peter G. Wolynes

Randall W. Hall

By defining a spatially varying replica overlap parameter for a supercooled liquid referenced to an ensemble of fiducial liquid state configurations, we explicitly construct a constrained replica free energy functional that maps directly onto an Ising Hamiltonian with both random fields and random interactions whose statistics depend on the liquid structure. Renormalization group results for random magnets when combined with these statistics for the Lennard-Jones glass suggest that discontinuous replica symmetry breaking would occur if a liquid with short range interactions could be equilibrated at a sufficiently low temperature where its mean field configurational entropy would vanish, even though the …

Microscopic Theory Of Network Glasses, Randall W. Hall, Peter G. Wolynes

Randall W. Hall

A theory of the glass transition of network liquids is developed using self-consistent phonon and liquid state approaches. The dynamical transition and entropy crisis characteristic of random first-order transitions are mapped as a function of the degree of bonding and density. Using a scaling relation for a soft-core model to crudely translate the densities into temperatures, theory predicts that the ratio of the dynamical transition temperature to the laboratory transition temperature rises as the degree of bonding increases, while the Kauzmann temperature falls explaining why highly coordinated liquids are “strong” while van der Waals liquids without coordination are “fragile.”

Constructing Explicit Magnetic Analogies For The Dynamics Of Glass Forming Liquids, Jacob D. Stevenson, Aleksandra M. Walczak, Randall W. Hall, Peter G. Wolynes

Randall W. Hall

By defining a spatially varying replica overlap parameter for a supercooled liquid referenced to an ensemble of fiducial liquid state configurations, we explicitly construct a constrained replica free energy functional that maps directly onto an Ising Hamiltonian with both random fields and random interactions whose statistics depend on the liquid structure. Renormalization group results for random magnets when combined with these statistics for the Lennard-Jones glass suggest that discontinuous replica symmetry breaking would occur if a liquid with short range interactions could be equilibrated at a sufficiently low temperature where its mean field configurational entropy would vanish, even though the …

New Measurements Of Mcmurdo Gravity Wave Parameters, Jonathan R. Pugmire, Michael J. Taylor, P Dominique Pautet

Jonathan Pugmire

The ANtarctic Gravity Wave Instrument Network (ANGWIN) is an NSF sponsored international program designed to develop and utilize a network of gravity wave observatories using existing and new instrumentation operated at several established research stations around the continent. The primary goal is to better understand and quantify large-scale gravity wave climatology and their effects on the upper atmosphere over Antarctica. ANGWIN currently comprises research measurements from five nations (U.S., U.K., Australia, Japan, and Brazil) at seven international stations. Utah State University’s Atmospheric Imaging Lab operates all-sky infrared and CCD imagers and an Advanced Mesospheric Temperature Mapper (AMTM) imager at several …

Quantitative Mid-Infrared Spectra Of Allene And Propyne From Room To High Temperatures, Et. Es-Sebbar, A. Jolly, Y. Benilan, A. Farooq

Dr. Et-touhami Es-sebbar

Allene (a-C3H4; CH2CCH2) and propyne (p-C3H4; CH3C2H) have attracted much interest because of their relevance to the photochemistry in astrophysical environments as well as in combustion processes. Both allene and propyne have strong absorption in the infrared region. In the present work, infrared spectra of a-C3H4 and p-C3H4 are measured in the gas phase at temperatures ranging from 296 to 510 K. The spectra are measured over the 580–3400 cm−1 spectral region at resolutions of 0.08 and 0.25 cm−1 using Fourier Transform Infrared spectroscopy. Absolute integrated intensities of the main infrared bands are determined at room temperature and compared with …

Rhodizonic Acid On Noble Metals: Surface Reactivity And Coordination Chemistry, Donna A. Kunkel, James Hooper, Scott Simpson, Sumit Beniwal, Katie L. Morrow, Douglas C. Smith, Kimberly Cousins, Stephen Ducharme, Eva Zurek, Axel Enders

Axel Enders

A study of the two-dimensional crystallization of rhodizonic acid on the crystalline surfaces of gold and copper is presented. Rhodizonic acid, a cyclic oxocarbon related to the ferroelectric croconic acid and the antiferroelectric squaric acid, has not been synthesized in bulk crystalline form yet. Capitalizing on surface-assisted molecular self-assembly, a two-dimensional analogue to the well-known solution-based coordination chemistry, two-dimensional structures of rhodizonic acid were stabilized under ultrahigh vacuum on Au(111) and Cu(111) surfaces. Scanning tunneling microscopy, coupled with first-principles calculations, reveals that on the less reactive Au surface, extended two-dimensional islands of rhodizonic acid are formed, in which the molecules …

Computational Study Of The Hydration Of Sulfuric Acid Dimers: Implications For Acid Dissociation And Aerosol Formation, Berhane Temelso, Thuong Ngoc Phan, George C. Shields

Berhane Temelso

We have investigated the thermodynamics of sulfuric acid dimer hydration using ab initio quantum mechanical methods. For (H2SO4)2(H2O)n where n = 0−6, we employed high-level ab initio calculations to locate the most stable minima for each cluster size. The results presented herein yield a detailed understanding of the first deprotonation of sulfuric acid as a function of temperature for a system consisting of two sulfuric acid molecules and up to six waters. At 0 K, a cluster of two sulfuric acid molecules and one water remains undissociated. Addition of a second water begins the deprotonation of the first sulfuric acid …

Ferromagnetic Granular Exchange Interactions Of Nickel And Iron, Ken Podolak

Dr. Ken Podolak

Micromagnetic grains of nickel and iron were blended to investigate whether the magnetic exchange interaction was significant to produce a bulk result in a measured deflection by a fixed applied magnetic field. The results follow the same trend as Slater-Pauling's magnetization density calculations for nickel iron films, most notably a stronger following with a finer grain. Furthermore, by adding chromium into nickel and iron blends, the Invar minimum shifts toward less iron in nickel. Hysteresis was determined for the same samples through a homemade vibrating sample magnetometer (VSM). Areas of each loop are determined that show a minimum around the …

Heterogeneous Rotational Diffusion Of A Fluorescent Probe In Lipid Monolayers, Christina M. Othon

Christina M Othon

The rotational correlation time of the lipid probe 1-palmitoyl-2-{6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl}-sn-glycero-3-phosphocholine (NBD-PC) is measured using fluorescence anisotropy for two lipid species. We measure the rotational diffusion in a monolayer of 1,2-Didecanoyl-sn-glycero-3-phosphocholine (DPPC) which displays a phase transition at room temperature from the liquid expanded to the liquid-condensed phase. The constant rotational diffusion of the probe throughout the phase transition reflects the measurement of dynamics in only the liquid-expanded phase. We contrast the dynamic changes during this phase coexistence to the continuous density increase observed in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) at room temperature. We observe a non-exponential decay of the probe diffusion consistent with heterogeneity …

Intensities, Broadening And Narrowing Parameters In The Ν3 Band Of Methane, Et-Touhami Es-Sebbar, Aamir Farooq

Dr. Et-touhami Es-sebbar

The P-branch of methane׳s ν3 band is probed to carry out an extensive study of the 2905–2908 cm−1 infrared spectral region. Absolute line intensities as well as N2-, O2-, H2-, He-, Ar- and CO2-broadening coefficients are determined for nine transitions at room temperature. Narrowing parameters due to the Dicke effect have also been investigated. A narrow emission line-width (~0.0001 cm−1) difference-frequency-generation (DFG) laser system is used as the tunable light source. To retrieve the CH4 spectroscopic parameters, Voigt and Galatry profiles were used to simulate the measured line shape of the individual transitions.

A Coordinated Investigation Of The Gravity Wavebreaking And The Associated Dynamicalinstability By A Na Lidar And An Advancedmesosphere Temperature Mapper Overlogan, Ut, Xuguang Cai

Xuguang Cai

No abstract provided.

Structure And Interactions Of Lipid Bilayers: Role Of Fluctuations, John F. Nagle, Stephanie Tristram-Nagle

Prof. Stephanie Tristram-Nagle Ph.D.

The cell is the fundamental unit in biology. Each cell is spatially defined by its cytoplasmic membrane. The structural basis for each membrane is lipid in bilayer form. Following this reductionist point of view, it is therefore not surprising that lipid bilayers have been much studied using a great variety of techniques.

C/2013 R1 (Lovejoy) At Ir Wavelengths And The Variability Of Co Abundances Among Oort Cloud Comets, L. Paganini, M. J. Mumma, G. L. Villanueva, J. V. Keane, G. A. Blake, B. P. Bonev, M. A. Disanti, E. L. Gibb, K. J. Meech

Erika Gibb

Investigation Of Carrier Transit Motion In Pcdtbt By Optical Shg Technique, Shahino Mah Abdullah

Shahino Mah Abdullah

We analyze the carrier transit behavior in poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT), which has been reported as a donor material for efficient bulk hetero junction photovolatic devices. The transfer and transient carrier mobilities in the PCDTBT thin films have been measured and analyzed. The transfer mobility has been measured by the transfer curve of the OFET, whereas, the transient mobility is recorded using a time-resolved electric-field-induced optical second-harmonic-generation (TRM-SHG) technique. Using TRM-SHG technique, the dynamic motion of the charge carriers in the PCDTBT thin films has been directly visualized. We anticipate that the analysis of the carrier motion by TRM-SHG, will be effective …

Detector Prototype Evaluation At Spallation Neutron Sources, Robert W. Pattie Jr.

Robert W. Pattie Jr.

No abstract provided.

Atomistic Simulations Of The Fusion-Plasma Material Interface, Mostafa Jon Dadras

Jonny Dadras

A key issue for the successful performance of current and future fusion reactors is understanding chemical and physical processes at the Plasma Material Interface (PMI). The material surfaces may be bombarded by plasma particles in a range of impact energies (1 eV - a few keV) and kept at a range of temperatures (300 - 1000 K). The dominant processes at the PMI are reflection and retention of impacting particles and sputtering (chemical and physical). Sputtering leads to surface erosion and pollution of the plasma, both of which degrade reactor performance. Retention influences the recycling of the plasma, and in …

Basic Astronomy Labs, Terry L. Smith, Michael D. Reynolds, Jay S. Huebner

Jay S Huebner

Providing the tools and know-how to apply the principles of astronomy first-hand, these 43 laboratory exercises each contain an introduction that clearly shows budding astronomers why the particular topic of that lab is of interest and relevant to astronomy. About one-third of the exercises are devoted solely to observation, and no mathematics is required beyond simple high school algebra and trigonometry.Organizes exercises into six major topics—sky, optics and spectroscopy, celestial mechanics, solar system, stellar properties, and exploration and other topics—providing clear outlines of what is involved in the exercise, its purpose, and what procedures and apparatus are to be used. …

Absorption Cross-Section Measurements Of Methane, Ethane, Ethylene And Methanol At High Temperatures, Majed Alrefae, Et-Touhami Es-Sebbar, Aamir Farooq

Dr. Et-touhami Es-sebbar

Mid-IR absorption cross-sections are measured for methane, ethane, ethylene and methanol over 2800–3400 cm−1 (2.9–3.6 μm) spectral region. Measurements are carried out using a Fourier-Transform-Infrared (FTIR) spectrometer with temperatures ranging 296–1100 K and pressures near atmospheric. As temperature increases, the peak cross-sections decrease but the wings of the bands increase as higher rotational lines appear. Integrated band intensity is also calculated over the measured spectral region and is found to be a very weak function of temperature. The absorption cross-sections of the relatively small fuels studied here show dependence on the bath gas. This effect is investigated by studying the …

Investigating Access To And Attitudes Toward Programming In A Physics Camp, Gina M. Quan, Ayush Gupta

Gina Quan

Measurements Of Linestrengths, N2-, Ar-, He- And Self-Broadening Coefficients Of Acetylene In The Ν4+Ν5 Combination Band Using A Cw Quantum Cascade Laser, Muhammad Bilal Sajid, Et-Touhami Es-Sebbar, Aamir Farooq

Dr. Et-touhami Es-sebbar

Linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene have been measured at 296 K in the P branch of the ν4+ν5 combination band for 25 rotational transitions. The effect of gas temperature is studied over 296–683 K for five transitions to allow the determination of the temperature dependent exponent n for N2- and Ar-broadening coefficients. These measurements were performed using a continuous-wave quantum cascade laser (cw-QCL) operating over 1253–1310 cm−1. Spectroscopic parameters were obtained by fitting absorption spectra using Voigt, Galatry and Rautian profiles. Linestrength and broadening results are compared with previous studies available in literature for the ν4+ν5 …

Testing The Well-Posedness Of Characteristic Evolution Of Scalar Waves, Maria Babiuc-Hamilton, Heinz Otto Kreiss, Jeffrey Winicour

Maria C. Babiuc-Hamilton

Recent results have revealed a critical way in which lower order terms affect the well-posedness of the characteristic initial value problem for the scalar wave equation. The proper choice of such terms can make the Cauchy problem for scalar waves well posed even on a background spacetime with closed lightlike curves. These results provide new guidance for developing stable characteristic evolution algorithms. In this regard, we present here the finite difference version of these recent results and implement them in a stable evolution code. We describe test results which validate the code and exhibit some of the interesting features due …

Apparatus For Studying Wave Motion And Sound At The University Of Nebraska– Lincoln's “Historical Scientific Instrument Gallery”, Lily M. Wang, M. Eugene Rudd

Lily M Wang

The University of Nebraska–Lincoln's “Historical Scientific Instrument Gallery,'' compiled by the second author in 1998, contains approximately 700 inventoried items and may be visited on-line at http://physics.unl.edu/outreach/histinstr/. Amidst the collection are several acoustical instruments that were used in the early 1900s. These include equipment that demonstrate wave motion (traveling wave machine, mercury ripple dish, vibration microscope), wave interference (interference machine), resonance conditions (Helmholtz resonators, vibrating rods, singing flames, sonometer), and sound generation (Galton's whistles, high-frequency tuning forks, large tuning forks, organ pipes, siren saw). A review of the equipment and the history of their use at the University of Nebraska …

Kinematical Conformal Cosmology: Fundamental Parameters From Astrophysical Observations, Gabriele U. Varieschi

Gabriele Varieschi

No abstract provided.

Eight Minutes And A Half, Gabriele U. Varieschi

Gabriele Varieschi

No abstract provided.

Measuring The Prompt Atmospheric Neutrino Flux With Down-Going Muons In Neutrino Telescopes, Gabriele U. Varieschi

Gabriele Varieschi

No abstract provided.

Measurement Of The Gluon Parton Distribution Function At Small X With Neutrino Telescopes, Gabriele U. Varieschi

Gabriele Varieschi

We analyze the possibility that neutrino telescopes may provide an experimental determination of the slope λ of the gluon distribution in the proton at momentum fractions x smaller than the accelerator reach. The method is based on a linear relation between λ and the spectral index ~slope! of the down-going atmospheric muon flux above 100 TeV, for which there is no background. Considering the uncertainties in the charm production cross section and in the cosmic ray composition, we estimate the error on the measurement of l through this method, excluding the experimental error of the telescopes, to be ±0.2.

The Projectile Inside The Loop, Gabriele U. Varieschi

Gabriele Varieschi

No abstract provided.

Prompt Atmospheric Neutrinos And Muons: Dependence On The Gluon Distribution Function, Gabriele U. Varieschi

Gabriele Varieschi

No abstract provided.