Physical Sciences and Mathematics Commons^™

Gamma-Ray Observations Of The Crab Region Using A Coded-Aperture Telescope, Mark L. Mcconnell, P. P. Dunphy, D J. Forrest, E. L. Chupp, A Owens

Physics & Astronomy

The region of the Galactic anticenter, including the Crab Nebula, was observed during a balloon flight of the University of New Hampshire Directional Gamma-Ray Telescope employing the coded-aperture imaging technique to image celestial gamma-radiation between 160 keV and 9.3 MeV. The background systematics are treated with a simple and relatively straightforward correction procedure. The results demonstrate that the coded-aperture procedure is a viable approach for imaging not only point sources of radiation, but also extended sources of emission. The results for the Crab's photon spectrum are consistent with a power-law spectrum. Upper limits on the flux levels of line emission …

Chromospherically Active Stars. Iii. Hd 26337 = Ei Eri: An Rs Cvn Candidate For The Doppler-Imaging Technique, Francis C. Fekel, Robert Quigley, Kim Gillies, John L. Africano

Information Systems and Engineering Management Research Publications

The variable star HD 26337 = EI Eri is a chromospherically active G5 IV single-lined spectroscopic binary with a period of 1.94722 days. It has moderate strength Ca II H and K emission and strong ultraviolet emission features, while Hα is a weak absorption feature that is variable in strength. The inclination of the system is 46°±12°, and the unseen secondary is most likely a late K or early M dwarf. The v sin i of the primary is 50±3 km s-1, resulting in a minimum radius of 1.9±0.1 R_sun;. A mass ratio of M1/M2 ≥ 2.6 and a mass …

Optical Variability Of The Black Hole Candidate Gx339-4 (X1659-487, V821 Ara) - Limits On Periodic Modulation, R. H. D. Corbet, J. R. Thorstensen, P. A. Charles, W. B. Honey

Dartmouth Scholarship

We present results of extensive CCD optical photometry (over 1000 frames representing ~150 hr of integration time) of the optical counterpart of the X-ray source GX339–4 obtained during the high (soft) state. The source was seen to be significantly variable. We do not, however, detect any periodic modulation with semi-amplitude greater than ~0.03 mag for periods less than ~0.5 day or semi-amplitude greater than ~0.07 mag for longer periods. An optical spectrum obtained shortly after GX339–4 made a transition from a ‘low’ to a ‘high’ state is also presented and compared with previous results. The width of the He II …

Membership In The Young Cluster Trumpler 37, Laurence A. Marschall, William F. Van Altena

Physics and Astronomy Faculty Publications

Astrometric positions for 1387 stars and proper motions for a subset of 1135 stars brighter than V=15 in a 1.5 degree surrounding the young open cluster Trumpler 37 are presented. Membership probabilities are presented for those stars with measured proper motions, and 486 stars with probabilities of >80% are identified.

Surface Conductance Of A Copper Wire In A Fluid At High Pressure, Daniel L. Decker

Faculty Publications

The three-dimensional flow of heat in a wire carrying a current and immersed in a liquid is solved in detail. Using this exact result the surface conductance of copper in petroleum ether has been measured as a function of pressure to 40 kbars. The measured surface conductance for copper in a fluid is very small, justifying approximations which yield results that are in agreement with a simplified one-dimensional heat-flow problem. Surprisingly, even at 40 kbars pressure a very large fraction of the joule heating within a wire with a length-to-diameter ratio of ~100 is dissipated through the ends of the …

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.

1300 Micron Continuum And C18o Line Mapping Of The Giant Molecular Cloud Cores In Orion, W49, And W51, F. Peter Schloerb, Ronald L. Snell, P. R. Schwartz

Astronomy Department Faculty Publication Series

Observations of the 1300-micron continuum emission and the C(O-18) spectral-line emission from three well-studied giant molecular cloud cores: Orion, W49, and W51 are presented. The observations were obtained at the Five College Radio Astronomy Observatory, and they provide a means to examine the consistency of these two methods to trace the column density structure of molecular clouds. A good general correlation is found between the 1300-micron continuum, which traces the column density of dust, and the C(O-18) J = 2-1 line emission, which traces the column density of molecular gas, when the effects of source temperature are taken into consideration. …

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 …

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, …