Physical Sciences and Mathematics Commons^™

Single-Shot Detection Of Wavepacket Evolution, M. B. Campbell, Thomas J. Bensky, Robert R. Jones

Physics

We have developed a new instrument for monitoring electronic wavepacket dynamics using a single electromagnetic pulse pair. The operation of the device is analogous to that of single-shot cross-correlators commonly used to monitor the temporal evolution of short laser pulses. We have used the instrument to probe wavepacket evolution over time scales ranging from 100 psec to less than 1 fsec. The device reduces the amount of time required to collect pump-probe time delay data by orders of magnitude, greatly reducing the deleterious effects of experimental drifts. In addition, the single-shot feature provides real-time feedback as to the affect of …

Effects Of Self-Avoidance On The Tubular Phase Of Anisotropic Membranes, Mark Bowick, Emmanuel Guitter

Physics - All Scholarship

We study the tubular phase of self-avoiding anisotropic membranes. We discuss the renormalizability of the model Hamiltonian describing this phase and derive from a renormalization group equation some general scaling relations for the exponents of the model. We show how particular choices of renormalization factors reproduce the Gaussian result, the Flory theory and the Gaussian Variational treatment of the problem. We then study the perturbative renormalization to one loop in the self-avoiding parameter using dimensional regularization and an epsilon-expansion about the upper critical dimension, and determine the critical exponents to first order in epsilon.

Harbor Plan For The Town Of Provincetown, Urban Harbors Institute, University Of Massachusetts Boston

Urban Harbors Institute Publications

Provincetown Harbor is an attractive focus of activity for the entire community which surrounds it. The Harbor area is a complex place that requires public attention to ensure appropriate use and a clean environment. The Provincetown Harbor Plan establishes practical steps to meet these goals. This Plan values the present character and activities within the Harbor area. Rather than seeking dramatic changes, the objective of the Plan is to enhance the Harbor through better management and by accomplishing a list of coordinated improvements.

The Plan envisions a future Provincetown Harbor with substantially greater access and a more pleasant character along …

Langmuir Monolayers As Disordered Solids: Strain-State Calculations Applied To Stearic Acid, David R. Swanson, Tadeusz Luty, Craig J. Eckhardt

Craig J. Eckhardt Publications

This paper presents a calculational procedure to determine the equilibrium phase for a given surface pressure π. The monolayer is treated as orientationally free tails grafted to a two-dimensional net formed by the head groups of the amphiphilic molecules. The head groups form a subsystem with translational degrees of freedom characterized by strain variables in the plane of the surface, and the tail groups compose a subsystem characterized by rotational degrees of freedom. The order in the monolayer derives indirectly from the crystalline head groups through translational–rotational coupling. A stress–strain relation is derived which shows the energetically most favorable path …

Crossover Dynamics For Polymer Simulation In Porous Media, V. Yamakov, D. Stauffer, A. Milchev, G.M. Foo, R.B. Pandey

Faculty Publications

Off-lattice Monte Carlo simulations show anomalous diffusion at intermediate times without a clear Rouse regime, for the motion of chains through a random porous medium.

Scanning Probe Nanolithography Of Conducting Metal Oxides, Chen-Jen Hung, Jianian Gui, Jay A. Switzer

Chemistry Faculty Research & Creative Works

The scanning tunneling microscope (STM) was used to form nanometer-size holes in thin conducting films of thallium (III) oxide. Hole formation was only observed when the process was performed in humid ambient conditions. The hole formation was attributed to localized electrochemical etching reactions beneath the STM tip. etching reactions consistent with the observed hole formation are a direct electrochemical reduction of thallium (III) oxide to soluble T1 (I) at negative sample bias, and local reduction of pH at positive sample bias. The fastest etching was observed at negative sample bias. Holes as small as 10 nm or as large as …

Locally Optimally Emitting Clouds And The Narrow Emission Lines In Seyfert Galaxies, Jason W. Ferguson, Kirk T. Korista, Jack A. Baldwin, Gary J. Ferland

Physics and Astronomy Faculty Publications

The narrow emission line spectra of active galactic nuclei are not accurately described by simple photoionization models of single clouds. Recent Hubble Space Telescope images of Seyfert 2 galaxies show that these objects are rich with ionization cones, knots, filaments, and strands of ionized gas. Here we extend to the narrow-line region the ``locally optimally emitting cloud'' (LOC) model, in which the observed spectra are predominantly determined by powerful selection effects. We present a large grid of photoionization models covering a wide range of physical conditions and show the optimal conditions for producing many of the strongest emission lines. We …

Field Trip Guide (For The Nebraska Well Drillers Association) Northeastern Nebraska Geology, Sue Olafsen Lackey, Robert F. Diffendal Jr., Raymond R. Burchett, Duane A. Eversoll, Rodney J. Tremblay

Conservation and Survey Division

Field trip guide, for the Nebraska Well Drillers Association, covering northeastern Nebraska geology from September 1997.

Singular Structure In 4d Simplicial Gravity, Simon Catterall, R. Renken, John B. Kogut

Physics - All Scholarship

We show that the phase transition previously observed in dynamical triangulation models of quantum gravity can be understood as being due to the creation of a singular link. The transition between singular and non-singular geometries as the gravitational coupling is varied appears to be first order.

Ionization Of Na Rydberg Atoms By Subpicosecond Quarter-Cycle Circularly Polarized Pulses, Thomas J. Bensky, G. Haeffler, Robert R. Jones

Physics

We report the first observation of ionization of Rydberg atoms by subpicosecond, circularly polarized THz radiation. The field amplitude in these pulses is non-negligible for only one-quarter of an optical cycle. The experiment is performed in the short-pulse regime, where the duration of the ionizing pulse is shorter than the classical Kepler period of the Rydberg electron. We find that the ionization probability for these atoms is remarkably insensitive to the time-varying polarization of the THz field.

Survey Of Mollusks Of The Niobrara River: Final Report, Patricia W. Freeman, Keith Perkins

School of Natural Resources: Faculty Publications

We surveyed the mollusks of the Niobrara River in Nebraska from 1992–1996. We found two species of unionid clams and ten species of snails that either must live in water or near water. Both clams and snails are poorly sampled in the state, however we attribute the low number of species of unionid clams in the Niobrara to its cold, fast flow and rocky bottom. In contrast, the Platte River is slower moving with a muddy bottom and has at least 11 species of unionid clams. Each species has been mapped with latitude/longitude coordinates. Specimens have been curated and are …

The Convergence Of The Solutions Of The Navier-Stokes Equations To That Of The Euler Equations, R. Temam, X. Wang

Mathematics and Statistics Faculty Research & Creative Works

In this article, we establish partial results concerning the convergence of the solutions of the Navier-Stokes equations to that of the Euler equations. Convergence is proved in space dimension two under a physically reasonable assumption, namely that the gradient of the pressure remains bounded at the boundary as the Reynolds number converges to infinity.

Inclination Effects In Spiral Galaxy Gravitational Lensing, Ariyeh Maller, Ricardo Flores, Joel Primack

Physics Faculty Works

Spheroidal components of spiral galaxies have been considered to be the only dynamically important component in gravitational lensing studies to date. Here we point out that including the disk component can have a significant effect, which depends on the disk inclination, on a variety of lensing properties that are relevant to present studies and future surveys. As an example, we look at the multiple image system B1600+434, which was recently identified as being lensed by a spiral galaxy. We find that by including the disk component, one can understand the fairly large image separation as being caused by the inclination …

Serotonin 5-Ht4 Agonist Activity Of A Series Of Meso-Azanoradamantane Benzamides, Daniel Becker, Roger Nosal, Clara I. Villamil, Gary Gullikson

Chemistry: Faculty Publications and Other Works

A series of meso-amino(methyl)azanoradamantane benzamides has been prepared and evaluated for 5-HT4agonism activity in the rat tunica muscularis mucosae (TMM) assay. Compound 8i is the most potent 5-HT4agonist in the series, with an EC50 of 217 nM.

Optically Transparent Composite Material And Process For Preparing Same, D. E. Day, James O. Stoffer, John M. Barr

Materials Science and Engineering Faculty Research & Creative Works

Glass ribbon-reinforced transparent polymer composites which provide excellent optical transparency and a low distortion level over a wide temperature range while exhibiting superior mechanical properties as compared to non- reinforced polymer counterparts, and equivalent properties as compared to glass fiber-reinforced counterparts.

Statistical Topography Of Glassy Interfaces, Alan Middleton, Chen Zeng, Jane Kondev, David Mcnamara

Physics - All Scholarship

Statistical topography of two-dimensional interfaces in the presence of quenched disorder is studied utilizing combinatorial optimization algorithms. Finite-size scaling is used to measure geometrical exponents associated with contour loops and fully packed loops. We find that contour-loop exponents depend on the type of disorder (periodic ``vs'' non-periodic) and they satisfy scaling relations characteristic of self-affine rough surfaces. Fully packed loops on the other hand are unaffected by disorder with geometrical exponents that take on their pure values.

Electron-Collision-Induced Alignment Of Rare Gases Near Threshold, V. Zeman, K. Bartschat, Timothy J. Gay, K. W. Trantham

Timothy J. Gay Publications

Results of a semirelativistic R-matrix calculation are compared with experimental values for light polarizations and alignment parameters of the second excited-state manifolds of neon and krypton following electron impact excitation. The calculations focus on the near-threshold regime, where negative-ion resonances have a significant effect on the atomic alignment. A grouping of the alignment values according to the electronic angular momentum J of the excited state is observed and qualitatively explained by angular momentum coupling considerations.

Voltammetry And Spectroelectrochemistry Of Metallofullerenes, Mark Anderson, Harry Dorn, Paul Burbank, James Gibson

Mark R. Anderson

No abstract is currently available.

D* Production In Deep Inelastic Scattering At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, R. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

This paper presents measurements of D*f± production in deep inelastic scattering from collisions between 27.5GeV positrons and 820GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel D*+ → (D0 → K-π+)π+ (+c.c.) has been used in the study. The e+p cross section for inclusive D*± production with 5 < Q2 < 100GeV2 and y < 0.7 is 5.3±1.0±0.8nb in the kinematic region 1.3 < pT(D*±) < 9.0GeV and |η(D*±) | < 1.5. Differential cross sections as functions of pT(D*±), η(D*±), W and Q2 are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in pT(D*±) and η(D*±), the charm contribution Fcc̄2(x,Q2) to the proton structure function is determined for Bjorken x between 2 · 10-4 and 5 · 10-3. © 1997 Elsevier Science B.V.

Measurement Of The Proton Structure Function F2 And ΣΓ*ΡTot At Low Q2 And Very Low X At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, E. Anselmo, R. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

A small electromagnetic sampling calorimeter, installed in the ZEUS experiment in 1995, significantly enhanced the acceptance for very low x and low Q2 inelastic neutral current scattering, e+p → e+X, at HERA. A measurement of the proton structure function F2 and the total virtual photon-proton (γ*p) cross-section is presented for 0.11 ≤ Q2 ≤ 0.65 GeV2 and 2 × 10-6 ≤ x ≤ 6 × 10-5, corresponding to a range in the γ*p c.m. energy of 100 ≤ W ≤ 230 GeV. Comparisons with various models are also presented. © 1997 Published by Elsevier Science B.V.

Ocena Oddziaływania Na Środowisko Na Przykładzie Zabudowy Pieca Indukcyjnego W "Krakodlew" S.A., Marian Mazur, Marek Bogacki, Robert Oleniacz

Robert Oleniacz

The paper presents the procedure and the results of the environmental impact assessment for the induction furnace installed in the company "Krakodlew" S.A. in Krakow (Poland). This furnace will allow heating and keeping the liquid feed (pig iron) and adjust the chemical composition, which will allow for the production of high-quality heavy castings. The need to perform an environmental impact assessment for objects of this type results from the binding legal regulations in Poland. The analysis included all the main components of the environment: air, soil, vegetation, soil and water environment, land surface and acoustic climate. It was found that …

Fluctuation Properties Of Precipitation. Part I: On Deviations Of Single-Size Drop Counts From The Poisson Distribution, Alexander Kostinski, A. R. Jameson

Department of Physics Publications

The traditional statistical description of the spatial and temporal distributions of cloud droplets and raindrops is the Poisson process, which tends to place the drops as uniformly as randomness allows. Yet, the “clumpy” nature of clouds and precipitation is apparent to most casual observers and well known to cloud physicists. Is such clumpiness consistent with the Poisson statistics? The authors explore the possibility of deviations from the Poisson distribution using temporal raindrop counting experiments. Disdrometer measurements during the passage of a squall line strongly indicate that a mixture of Poisson distributions (Poisson mixture) provides a better description of the frequency …

Effect Of Bmp Implementation On Storm Flow Quality Of Two Northwestern Arkansas Streams, Dwayne R. Edwards, Tommy C. Daniel, H. Don Scott, Phillip A. Moore Jr., John F. Murdoch, Paul F. Vendrell

Biosystems and Agricultural Engineering Faculty Publications

The effectiveness of management practices in improving quality of runoff from agricultural land areas has been reported based primarily on results from plot- and field-scale studies. There is limited information available on watershed scales, particularly when the dominant agricultural land use is pasture. The objective of this study was to determine whether a program of Best Management Practice (BMP) implementation in the Lincoln Lake watershed of northwestern Arkansas was effective in reducing storm stream flow concentrations and mass transport of nitrate nitrogen (NO₃-N), ammonia nitrogen (NH₃-N), total Kjeldahl nitrogen (TKN), ortho-phosphorus (PO₄-P), total phosphorus …

Attractors For Nonautonomous Nonhomogeneous Navier-Stokes Equations, A. Miranville, X. Wang

Mathematics and Statistics Faculty Research & Creative Works

In this paper our aim is to derive an upper bound on the dimension of the attractor of the family of processes associated to the Navier-Stokes equations with nonhomogeneous boundary conditions depending on time. We consider two-dimensional flows with prescribed quasiperiodic (in time) tangential velocity at the boundary, and obtain an upper bound which is polynomial with respect to the viscosity.

The Probe, Issue 180 - September 1997

The Probe: Newsletter of the National Animal Damage Control Association

CONTENTS:
Vertebrate Repellents: Mechanisms, Practical Applications, Possibilities
CALENDAR OF UPCOMING EVENTS
NADCA Officers' Nominations Needed
Person-to-Person Hantavirus Reported
The Uneasy Conscience of the Animal Rights Movement: Part 2
Children Attacked, One Killed by Colorado Lions
Coyotes as Safety Threat Debated

High Coercivity Smfealc Thin Films Fabricated By Multilayer Sputtering, M.L. Yan, Z.S. Shan, Yi Liu, David J. Sellmyer

David Sellmyer Publications

Multilayer sputtering of SmFe/C(Al) plus appropriate thermal processing has been used to fabricate SmFeC thin films with A1 substitution for Fe. It was found that the SmFeAlC thin films exhibited exceptionally high Coercivities. A coercivity of 28 kOe was realized for the thin film with structure of Ta(l000 Å)/|SmFe(40Å)/ C(Al)(5Å)]x50/Ta(200Å) with subsequent annealing at 650°C.

Magnetic And Structural Properties Of Sm2Fe10Co7/MXCY Thin Films, I.A. Al-Omari, N. J. Cunningham, David J. Sellmyer

David Sellmyer Publications

The structural and magnetic properties of Sm₂Fe₁₀Co₇/M_xC_y (M=A1 and Si; x≥0 and y≥0) multilayer films with Ta underlayers and overlayers before and after annealing at 700 °C for 5-12 min have been fabricated and studied. Structural studies show evidence of layer diffusion upon annealing. X-ray diffraction shows that the samples after annealing consist of a soft phase, α -Fe, and a hard phase with the 2-17-type structure. The samples studied have in-plane anisotropy with single hysteresis loops indicating that the two phases are strongly exchange coupled. After annealing, the coercivity of …

“Atomic Processes In High Energy Density Plasmas," Summaries Of Fy 1997 Research In The Chemical Sciences, Donald P. Umstadter

Donald Umstadter Publications

Several important plasma atomic processes are studied in a controlled manner. These studies are enabled by the recent invention of ultrashortpulse- duration lasers, which produce plasmas with independently controllable parameters.

Segregation Of Bismuth To Triple Junctions In Copper, K.-M. Yin, Alexander H. King, T.E. Hsieh, F.-R. Chen, J.J. Kai, L. Chang

Alexander H. King

Bismuth segregation in copper has been studied using energy-dispersive X-ray spectrometry (EDX) in a JEOL 2010F transmission electron microscope. In addition to the expected solute enrichment at grain boundaries, we have observed extremely high concentrations of bismuth at certain triple junctions, with significantly greater enrichment factors than in the adjacent grain boundaries. It is shown here that the triple junction segregation is a function of the parameters of the grain boundaries at the triple line, and existence of this type of segregation implies that the affected triple junctions embody excess free energy. At least one of the observed triple junctions …

Vibrational Spectra In Ordered And Disordered Ni3al, Jeffrey D. Althoff, Dane Morgan, Didier De Fontaine, Mark Asta, S. M. Foiles, Duane D. Johnson

Duane D. Johnson

We calculate the vibrational density of states (DOS) and corresponding thermodynamic properties of L12 ordered and disordered Ni3Al in the quasiharmonic approximation using the embedded-atom method. Vibrational and thermodynamic properties, including vibrational entropy differences between ordered and disordered states, are found to be in good agreement with experiment. The DOS of the configurationally disordered alloy resembles a broadened version of the DOS of the L12 phase, not a one-atom per cell fcc DOS, and is shifted downward in frequency because the disordered state has a larger volume than the ordered phase. Calculations of the projected DOS indicate that high-frequency modes …