Physical Sciences and Mathematics Commons^™

Superconductivity At 155 K, David D. Allred, S. R. Ovshinsky, R. T. Young, G. Demaggio, G. A. Van Der Leeden

Faculty Publications

Transition to a superconducting zero-resistance state at 155 K is observed for the first time in bulk material. A new five-element compound has been synthesized with nominal composition Y1Ba2Cu3F2Oy. Fluorine plays a critical role in achieving this effect. X-ray diffraction and electron microprobe analysis indicate that the samples are multiphasic. Evidence is presented that the samples contain superconducting phases with onset temperatures considerably above 155 K. Magnetic measurements suggest a flux-trapping effect below 260 K, and diamagnetic deviations from Curie-Weiss behavior in the range from 250 K≤T≤100 K indicate that Meissner effect in a small superconducting volume fraction.

Some Aspects Of The Isogroup Of The Self-Dual Yang-Mills System, C. J. Papachristou, B. Kent Harrison

Faculty Publications

A generalized isovector formalism is used to derive the isovectors and isogroup of the self-dual Yang-Mills (SDYM) equation in the so-called J formulation. In particular, the infinitesimal "hidden symmetry'' transformation, a linear system, and a well-known Backlund transformation of the SDYM equation are derived in the process. Thus symmetry and integrability aspects of the SDYM system appear in natural relationship to each other within the framework of the isovector approach.

Rise To Power Of Senator Joseph R. Mccarthy: Reflections Of The Cold War Mccarthy Era In American Film, Scott Lainer

Honors Theses

The common bond between much of the film industry and Joseph McCarthy was insecurity and the drive for national approval. If one grasps the specific characteristics of McCarthy the man, and the methods of these politically "inspired" movies, we can to better place the period into context and acknowledge the fact that, if the citizenry is not aware, and is again caught by an ever-building wave of trickle down sentiment, the 1950s might not prove to be an isolated period in American history. Insecurity was not a fifties novelty. It still exists, and could potentially escalate anti-Communist policy and sentiment …

Upwind And Symmetric Shock- Capturing Schemes, H.C. Yee

United States National Aeronautics and Space Administration: Publications

The development of numerical methods for hyperbolic conservation laws has been a rapidly growing area for the last ten years. Many of the fundamental concepts and state-of-the-art developments can only be found in meeting proceedings or internal reports. This review paper attempts to give an overview and a unified formulation of a class of shock-capturing methods. Special emphasis will be on the construction of the basic nonlinear scalar second-order schemes and the methods of extending these nonlinear scalar schemes to nonlinear systems via the exact Riemann solver, approximate Riemann solvers, and flux-vector splitting approaches. Generalization of these methods to efficiently …

Molecular Clouds And Cloud Cores In The Inner Galaxy, N Z. Scoville, Min S. Yun, D B. Sanders, D P. Clemens, W H. Waller

Min S. Yun

A compilation of CO emission regions and their measured parameters is presented which represents a nearly complete accounting of the molecular clouds in the first quadrant of the Galaxy. Emission regions associated with radio H II regions have systematically brighter CO peaks that are a factor of two to three times larger and have twice the mean velocity dispersion as the general cloud population. Both the H II region clouds and the hot core regions have a Galactic distribution characteristic of a spiral arm population, whereas the colder clouds are much less confined in Galactic azimuthal angle. Virial masses are …

Implicit Tvd Schemes For Hyperbolic Conservation Laws In Curvilinear Coordinates, Helen Yee, A. Harten

United States National Aeronautics and Space Administration: Publications

A one-parameter family of explicit and implicit upwind second-order-accurate, total variation diminishing (TVD) schemes has been developed by Harten. These TVD schemes have the property of not generating spurious oscillations when applied to one-dimensional nonlinear scalar hyperbolic conservation laws and constant coefficient hyperbolic systems. The goal of this work is to extend these methods to the multidimensional hyperbolic conservation laws in curvilinear coordinates. Various ways of linearizing the implicit operator and solution strategies to improve the computation efficiency of the implicit algorithm are discussed. Numerical experiments with some AGARD test cases for steady-state airfoil calculations show that the proposed linearized …

Explorations, Vol. 3, No. 2, Maryann Jerkofsky, David H. Clark, David Ebitz, Alan Davenport, David C. Smith, Erodgan Kiran

Explorations — A Journal of Research

Cover: Edmund G. Schildknecht, Seated Figure, 1929, oil on canvas, 30” x 25”, acc. no. 85.6.31, bequest of Edmund G. Schildknecht

Articles include:
"Reyes Syndrome Under Attack at UMaine," by MaryAnn Jerkofsky

"Maine Service Abroad: Using Labor Market Results for Planning Education and Training in Developing Countries," by David H. Clark

"Feeling and Form: Four American Paintings in the University of Maine Art Collection," by David Ebitz

"We Stand Corrected," Volume 3, Number 1, of EXPLORATIONS

"Confessions of a Comet Huckster," by Alan Davenport

"H.G. Wells: Socialist, Feminist, Polymath, Educator and Hero," by David C. Smith

"Supercritical Fluids and …

Fluctuating Hydrodynamics In A Dilute Gas, Alejandro Garcia, G. Lie, E. Clementi

Faculty Publications

Hydrodynamic fluctuations in a dilute gas subjected to a constant heat flux are studied by both a computer simulation and the Landau-Lifshitz formalism. The latter explicitly incorporates the boundary conditions of the finite system, thus permitting quantitative comparison with the former. Good agreement is demonstrated.

Hydrodynamic Fluctuations In A Fluid Under Constant Shear, Alejandro Garcia, M. Malek Mansour, G. Lie, E. Clementi, M. Mareschal

Faculty Publications

No abstract provided.

Fluctuating Hydrodynamics In A Dilute Gas, Alejandro Garcia, G. Lie, E. Clementi

Alejandro Garcia

Hydrodynamic fluctuations in a dilute gas subjected to a constant heat flux are studied by both a computer simulation and the Landau-Lifshitz formalism. The latter explicitly incorporates the boundary conditions of the finite system, thus permitting quantitative comparison with the former. Good agreement is demonstrated.

Hydrodynamic Fluctuations In A Fluid Under Constant Shear, Alejandro Garcia, M. Malek Mansour, G. Lie, E. Clementi, M. Mareschal

Alejandro Garcia

No abstract provided.

Supershells And Propagating Star Formation, R. Mccray, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

Stellar winds and repeated supernovae from an OB association will create a cavity of coronal gas in the interstellar medium, with radius greater than 100 pc, surrounded by a dense, expanding shell of cool interstellar gas. If the association has a typical initial mass function, its supernovae explosions will inject energy into the supershell at a nearly constant rate for about 5 x 10^7 yr. The supershell loses its interior pressure and enters the snowplow phase when radiative cooling becomes important or when the shell bursts through the gas disk of a galaxy, typically after a few times 10^7 yr …

The Large Scale Radio Structure Of R Aquarii, J. M. Hollis, Menas Kafatos, A. G. Michalitsianos, R. J. Oliverson, F. Yusef-Zadeh

Mathematics, Physics, and Computer Science Faculty Articles and Research

Radio continuum observations of the R Aquarii symbiotic star system, using the compact D configuration of the VLA at 6 em wavelength, reveal a large-scale ~2' structure engulfing the binary which has long been known to have a similar optical nebula. This optical/radio nebula possesses - 4 X 10^42 ergs of kinetic energy which is typical of a recurrent nova outburst. Moreover, a cluster of a dozen additional 6 em radio sources were observed in proximity to R Aquarii; most of these discrete sources lie ~3' south and/ or west of R Aquarii and, coupled with previous 20 cm data, …

Anneal Induced Changes In Amorphous Semiconductor Multilayers, David D. Allred, Jesus González-Hernández, O. V. Nguyen

Faculty Publications

We have prepared, heat treated and characterized various amorphous semiconductor periodic multilayers and ultrathin films. These were prepared by several vapor deposition techniques at substrate temperatures ranging from 25°C to 300°C and possessed periodicities from 22 to 400Å. Films were subjected to isochronal thermal treatments at progressively higher temperatures. Two effects were observed: enhanced diffusion and retarded crystallization. Interdiffusion, at rates which are many orders of magnitude higher than those anticipated from crystalline data, was observed in a-Si/a-Ge multilayers. Crystallization of germanium, the more readily crystallized member of the couple, is retarded; the extent depends on the thickness of the …

Chromospherically Active Stars. Ii. Hd 82558, A Young Single By Draconis Variable., Francis C. Fekel, Bernard W. Bopp, John L. Africano, Bret D. Goodrich, Leigh Hunter Palmer, Robert Quingley, Theodore Simon

Information Systems and Engineering Management Research Publications

It is presently noted that the HD 82558 chromospherically active star is a young and rapidly rotating K2 V single BY Draconis variable with very strong far-UV emission features and an H-alpha line filled to the continuum level by emission. HD 82558 has constant velocity and is not a member of the Hyades Supercluster. Its light curve behavior, which appears to have been stable for several hundred rotation cycles, is reminiscent of that of the young, rapidly rotating, single K V variable H II 1883 in the Pleiades; this stability may be characteristic of young, single, chromospherically active stars.

Equilibrium Properties Of Short Field-Reversed Configurations, Ross L. Spencer, M. Tuszewski

Faculty Publications

Some features of short field-reversed configuration (FRC) equilibria relevant to transport and stability are studied numerically and analytically. It is shown that magnetic field curvature effects significantly increase the FRC magnetization for plasma elongations epsilon is less than or equal to 4.

The Orbital Period Of The Optical/X-Ray Burster X1735-444 (V926 Sco), R. H. D. Corbet, J. R. Thorstensen, P. A. Charles, J. W. Menzies

Dartmouth Scholarship

We present extensive CCD photometry of the optical counterpart of X1735–444 which reveals the orbital period of the system. It is periodically variable with a period of 4.654 hr and a full amplitude of 0.15 mag. The mean modulation is quasi-sinusoidal; there are, however, also significant intrinsic deviations from the mean light curve.

Considerations Of Temperature Stability In A Cylindrical Plasma, S. Neil Rasband, Yao-Hui Xu

Faculty Publications

A variational formulation is used to consider thermal equilibrium and stability for a cylindrical plasma modeled by dissipative magnetohydrodynamics. The parameter dependence of equilibrium solutions and their stability is followed using homotopy techniques. Solution branches and their connections are studied in relation to the applied fields.

Radiation Pressure And Emission Clouds Around Active Galactic Nuclei, Moshe Elitzur, Gary J. Ferland

Physics and Astronomy Faculty Publications

Detailed calculations of the contribution of the trapped line photons to the overall pressure in line-emitting regions around active galactic nuclei are presented. They lead to the conclusion that radiation pressure is a significant factor in determining the stability of these clouds.

Nonequilibrium Fluctuations Studied By A Rarefied Gas Simulation, Alejandro Garcia

Faculty Publications

A dilute gas under a constant heat flux is studied with use of a Monte Carlo simulation based on the Boltzmann equation. Results for several spatial correlation functions of equal-time fluctuations are reported and compared qualitatively with previous fluctuating hydrodynamics calculations for liquids.

Nonequilibrium Fluctuations Studied By A Rarefied Gas Simulation, Alejandro Garcia

Alejandro Garcia

A dilute gas under a constant heat flux is studied with use of a Monte Carlo simulation based on the Boltzmann equation. Results for several spatial correlation functions of equal-time fluctuations are reported and compared qualitatively with previous fluctuating hydrodynamics calculations for liquids.

Evidence For Extended Radio Emission Surrounding Rx Puppis, J. M. Hollis, R. J. Oliverson, Menas Kafatos, A. G. Michalitsianos

Mathematics, Physics, and Computer Science Faculty Articles and Research

We report evidence for ~1" extended structure in 6 cm continuum emission emanating from the symbiotic star system RX Puppis. We did not detect hourly continuum flux changes as suggested in previous radio experiments by others. Our observations indicate that the predominant nature of the radio emission is thermal and consistent with an optically thick stellar wind emanating from the symbiotic star system. Our results are discussed with regard to other similar stellar binary systems.

Periods Of Eo And Fv Comae Berenices And The Functional Forms Of Their O-C Diagrams, Mark Anthony Reynolds

Publications

New elements are given for the RRab Lyrae variables EO Comae Berenices and FV Comae Berenices. The statistical significance of higher order terms in a polynomial least squares fit is discussed.

Sub-Arc Second 2 Centimeter Continuum And Sio Spectral Line Observations Of R Aquarii, J. M. Hollis, A. G. Michalitsianos, Menas Kafatos, M. C. H. Wright, W. J. Welch

Mathematics, Physics, and Computer Science Faculty Articles and Research

ub-arc second (- 0'.'15) VLA observations at 2 em have resolved the previously reported 6 em H II region, which engulfs the R Aquarii binary system, into two components. The stronger 2 em component is itself partially resolved (distorted in shape), which may be a consequence of the long-period variable (LPV) wind being subjected to the intense ionizing radiation field of the hot companion's accretion disk, which we suspect is precessing. The distorted radio contours of the central H II region may also suggest that one hemisphere of the extended LPV envelope is directly illuminated by the intense radiation field …

The Unusual Ultraviolet Variability Of The Qso 3c 232, C. Bruhweilier, Menas Kafatos, U. J. Sofia

Mathematics, Physics, and Computer Science Faculty Articles and Research

After examining ultraviolet IUE spectra of 18 QSOs with z > 0.35, we find that one object, 3C 232 (z = 0.533), stands out as exhibiting highly unusual spectral and continuum variability. The H 1-Lya shows at least 50% variability on a time scale of roughly a month, while the ultraviolet continuum exhibited approximately a factor of 2 decrease in a day. The magnitude of the UV continuum variability is reminiscent of that seen in the optically violent variables at visual wavelengths. Several spectral features at wavelengths shortward of H I-Lya in the rest frame are identified. A brief discussion COJ?lparing …

Bowen Fluoresence And He Ii Lines In Active Galaxies And Gaseous Nebulae, Hagai Netzer, Moshe Elitzur, Gary J. Ferland

Physics and Astronomy Faculty Publications

We have calculated the intensity of He II and the O III and N III Bowen lines under a variety of astrophysical conditions. Our line-transfer method is based on the escape probability formalism and is especially suitable for combining line fluorescence and photoionization calculations in a simple, straightforward way. It reproduces the results of the more sophisticated line-transfer calculations quite accurately and is much better for producing realistic ionization and thermal structures. An extensive grid of models is presented and discussed, with special emphasis on the case of active galactic nuclei (AGNs). Many O III and N III Bowen lines …

Chromospherically Active Stars. I. Hd 136905., Francis C. Fekel, Douglas S. Hall, John L. Africano, Kim Gillies, Robert Quigley, Robert E. Fried

Information Systems and Engineering Management Research Publications

The variable star HD 136905, recently designated GX Librae, is a chromospherically active K1 III single-lined spectroscopic binary with a period of 11.1345 days. It has moderate strength Ca II H and K and ultraviolet emission features, while Hα is strongly in absorption. The inclination of the systems is 58°±17° and the unseen secondary is most likely a G or K dwarf. The v sin i of the primary, 32±2 km s-1, results in a minimum radius of 7.0±0.4 R_sun;. Since the star fills a substantial fraction of its Roche lobe, the double-peaked light curve seen by photometric observers is …

A Generalized Molien Function For Field Theoretical Hamiltonians, Jeffrey W. Felix, Dorian M. Hatch

Faculty Publications

A generating function, or Molien function, the coefficients of which give the number of independent polynomial invariants in G, has been useful in the Landau and renormalization group theories of phase transitions. Here a generalized Molien function for a field theoretical Hamiltonian (with short-range interactions) of the most general form invariant in a group G is derived. This form is useful for more general renormalization group calculations. Its Taylor series is calculated to low order for the FGamma-2 representation of the space group R[3 bar]c and also for the l=1 (faithful) representation of SO(3).

Geodesic Orbits About An Axisymmetric Mass Distribution, David J. Dean

Honors Theses

The General Theory of Relativity (GRT) gives rise to many interesting questions, one of which is a question about how test particles orbit various relativistic mass configurations. A test particle is defined as an electrically neutral particle small enough that its self gravitating energy, as calculated using standard Newtonian theory, can be neglected when compared with the particle's rest mass, ie. M/R << 1. (Here M is the mass of the particle in meters, and R is the radius of the particle again in meters. The mass of the sun in these units is 1.47 km.) For example, the earth, which can be considered a test particle for the sun, travels about the sun in an elliptic orbit. What would happen if the sun suddenly became a black-hole? How would the earth's orbit be affected? It is the purpose of this paper to answer these questions not only for the case of the spherical black-hole (which has been extensively studied), but also for the case of an axisymmetric mass distribution idealized by a long thin rod-like mass (which will henceforth be referred to as a line mass). The classical case and relativistic case concerning orbits about the line mass will be discussed, along with some interesting features of the relativistic line mass orbits. Some background information concerning GRT will be needed before the problem of line mass is approached.

A 73.8 Mhz Radio Interferometer Telescope For Intense Celestial Sources, William Charles Millar

Masters Theses

A 73.8 MHz radio interferometer telescope was built, based on a published design. Although the design was proven, the telescope has thus far given no results on celestial sources. The electronics has been proven to be operational by testing them with hand-held dipole radio sources. Here, the electronics is evaluated with a discussion of possible reasons for the failure of the telescope in overall operation.