Physical Sciences and Mathematics Commons^™

Average Vertical And Zonal F-Region Plasma Drifts Over Jicamarca, Bela G. Fejer, E. R. De Paula, S. Gonzalez, R. F. Woodman

Bela G. Fejer

The seasonal averages of the equatorial F region vertical and zonal plasma drifts are determined using extensive incoherent scatter radar observations from Jicamarca during 1968–1988. The late afternoon and nighttime vertical and zonal drifts are strongly dependent on the 10.7-cm solar flux. We show that the evening prereversal enhancement of vertical drifts increases linearly with solar flux during equinox but tends to saturate for large fluxes during southern hemisphere winter. We examine in detail, for the first time, the seasonal variation of the zonal plasma drifts and their dependence on solar flux and magnetic activity. The seasonal effects on the …

Boundary C1, Α Regularity For Variational Inequalities, Fang-Hua Lin, Yi Li

Yi Li

No abstract provided.

Chelation Of 2-Substituted 1-Lithoxides: Structural And Energetic Factors Of Relevance To Synthetic Organic Chemistry., Michael Nichols, Andrew Mcphail, Edward Arnett

Michael A Nichols

No abstract provided.

Three-Point Correlations In Driven Diffusive Systems With Ising Symmetry, Beate Schmittmann, R. K. P. Zia

Beate Schmittmann

For equilibrium systems with Ising symmetry, the three-point correlation function is always zero above criticality. When a lattice-gas version of this system is driven to a nonequilibrium steady state, this correlation becomes nontrivial. Its dominant large-scale behavior is found to be a consequence of both the manifest breaking of Ising symmetry by the driving force and the more subtle violation of the fluctuation-dissipation theorem.

Handling Constraints In Genetic Algorithms, Cezary Janikow, Zbigniew Michalewicz

Cezary Janikow

Characterization Of Adsorption By Electrochemical And Spectroscopic Methods, Mark Anderson

Mark R. Anderson

No abstract is available at this time.

Parallel Algorithms For Graph Problems, Panagiotis T. Metaxas

Panagiotis T Metaxas

PhD Thesis about computing connected components in parallel.

Systematic Survey Of Cyclic Silicon-Oxygen Compounds, Michael W. Schmidt, Kiet A. Nguyen, Mark S. Gordon, John A. Montgomery Jr.

Mark S. Gordon

Compounds with 0, 1, 2, or 3 oxygen atoms bridging 2 silicon atoms are investigated by ab initio calculations. Two such series of compounds, with and without a formal central Si-Si bond, are considered. The triplet states of the former set are also examined. For some of these compounds, the present calculations represent the first time they have been examined at a sufficiently rigorous level of theory. For the compounds that are formally bonded, this level is two configuration SCF (TCSCF) for singlets and ROHF for triplet states, using split valence polarized basis sets. The main result is that no …

A Theoretical Study Of Some Reactions Of Hcsi-, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

The ions HCSi- and H2CSiH- produced in recent flowing afterglow experiments are characterized structurally. Reactivity of the former ion with four molecules (C02, OCS, CS2, S02) is examined. Three of these species react in a sequence of intermediates of cyclic followed by acyclic structures, before reaching the final products.

Principal Resonance Contributors To High-Valent, Transition-Metal Alkylidene Complexes, Thomas R. Cundiari, Mark S. Gordon

Mark S. Gordon

The results of ab initio calculations are reported for prototypical high-valent, alkylidene complexes. Stationary points on each potential energy surface are characterized and compared to experimental information where available; as long as a suitably flexible valence basis set is used, good agreement between theoretically calculated and experimentally determined geometries is obtained. The complexes of interest include group IVB (Ti, Zr and Hf) and group VB (Nb and Ta) alkylidenes with hydride ligands as well as models for the four-coordinate, olefin metathesis catalysts (Mo-, W-, and Re-alkylidenes) which have been recently synthesized and characterized. In light of the fact that much …

Interpretation Issues In Force Microscopy, Nancy Burnham, Richard Colton, Hubert Pollock

Nancy A. Burnham

In this paper, we will discuss force microscopy (FM) and its potential for determining mechanical properties of thin films. We will introduce the basic principles of FM, and demonstrate how FM can be used to determine materials properties as well as image surface topography, both with nanonewton or sub‐nanonewton force resolution and sub‐nanometer position resolution. As FM is still a new field, not all of the questions concerning interpretation have been fully answered. We will elucidate four current issues that must be resolved before the full potential of FM can be realized. They are: (1) the role of water vapor …

Setting Time Effects On Bentonite Water-Well Annulus Seals, Fred L. Ogden

Fred L. Ogden

Shear strength tests are conducted in a model of a water well on four, commercially available, granular bentonite well sealing products. The time dependency of annulus seal shear strength and resistance to piping is examined. Dry bentonite samples are placed through water in the annular space between the casing and borehole and allowed to set for a specified time. Pressure is applied at a constant rate to one end of the clay seal until shear or piping failure occurs. Pressure and seal displacement data are recorded on a digital data acquisition system. Annulus seal strength and resistance to piping increase …

The Influence Of Cation Size Upon The Infrared Spectrum Of Carbon Monoxide Adsorbed On Platinum Electrodes, Mark Anderson, Jimin Huang

Mark R. Anderson

No abstract is currently available.

Finger Formation In A Driven Diffusive System, D. H. Boal, Beate Schmittmann, R. K. P. Zia

Beate Schmittmann

A driven diffusive lattice gas is studied in a rectangular geometry: particles are fed in at one side and extracted at the other, after being swept through the system by a uniform driving field. Being periodic in the transverse direction, the lattice lies on the surface of a cylinder. The resulting nonequilibrium steady state depends strongly on this choice of boundary conditions. Both Monte Carlo and analytic techniques are employed to investigate the structure of typical configurations, the density profile, the steady-state current, and the nearest-neighbor correlations. As the temperature is lowered in a finite system, the simulations indicate a …

The Influence Of Cation Size Upon The Infrared Spectrum Of Carbon Monoxide Adsorbed On Platinum Electrodes, Mark Anderson, Jimin Huang

Mark R. Anderson

No abstract is currently available.

A New Twist On Pseudorotation, Theresa L. Windus, Mark S. Gordon, Larry W. Burggraf, Larry P. Davis

Mark S. Gordon

For pentacoordinated structures in a trigonal bipyramidal ar· rangement, Berry1 proposed a "pseudorotation" mechanism whereby two such isomers can interconvert through a tetragonal transition state (TS). This Berry pseudorotation mechanism was demonstrated explicitly for SiH5- by following the MP22/6· 31G(d)3 minimum energy path4 (MEP).

Observability Of The Anapole Moment And Neutrino Charge Radius, Mj Musolf, Br Holstein

Barry R Holstein

The properties of the neutrino charge radius (NCR) and anapole moments (AM's) of elementary fermions, nucleons, and nuclei are discussed. The dependence of these off-shell electromagnetic couplings on the weak gauge parameter is explicitly demonstrated by a calculation performed in the Rξ gauge. The gauge dependence of the AM's and NCR implies that they cannot be observed in isolation from other second-order, electroweak effects. It is shown, however, that the AM's of various hadronic systems having an SU(2)L quantum number TL3=0 can be considered ``observables'' in certain formal, though unphysical, limits. It is argued that, apart from these special limits, …

Thermochronology And Thermobarometry In Lithotectonic Zones In Eastern New England, Andrea Koziol, Robert Wintsch

Andrea M. Koziol

Sniftirs Study Of The Behavior Of The Spectrum Of Carbon Monoxide Adsorbed On A Platinum Electrode In Alcoholic Solvents, Andrea Russell, Daniel Blackwood, Mark Anderson, Stanley Pons

Mark R. Anderson

The vibrational spectrum of carbon monoxide as a function of coverage in various alcoholic solvents was investigated using the SNIFTIRS technique. At low coverage the potential dependence of the band position was found to be linearly dependent on the inverse of the bulk dielectric constant of the solvent. An electrostatic model was developed to represent the interaction between adjacent adsorbate molecules. This model provides evidence in support of an island formation mechanism.

Transport Processes And Traveling Waves In Systems With Local Nonequilibrium, Sergey Sobolev

Sergey Sobolev

No abstract provided.

Gas-Phase Chemistry Of The Dimethylaluminum Oxide Ion And Related Aluminum Oxide Ions: Comparison Of Reactivity With Siloxide Ions, Robert Damrauer, Michèle Krempp, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

The anion [(CH3hAIOt (1) has been prepared in a flowing afterglow selected ion flow tube (FA-SIFT) by ion selection from the reaction mixture of trimethylaluminum dimer and hydroxide. This unusual ion is quite reactive and has been extensively studied. It reacts with halogen-containing compounds of several types, including fluorobenzene, chlorobenzene, bromofluorobenzene, acetyl chloride, and HF, to give [(CH3hAI(OH)Xt, where X = F, Cl, and Br. Its chemistry with hexafluorobenzene and silicon tetrafluoride has also been detailed as have a number of reactions with carboxylic acids, esters, anhydrides, sulfur-containing neutrals, alcohols, water, and ammonia. The dominant reaction pattern of 1 involves …

Origins Of Compositional Order In Nipt Alloys, F. J. Pinski, B. Ginatempo, Duane D. Johnson, J. B. Staunton, G. M. Stocks, B. L. Gyorffy

Duane D. Johnson

We investigate the cause of compositional ordering in fcc Ni0.50Pt0.50 on the basis of a first-principles theory of electronic structure and finite-temperature concentration fluctuations. We treat the size effect, electronegativity, and band filling on an equal footing and find that the first of these dominates, leading to L10 ordering in agreement with experiment. An electronic origin is given for the metallurgical ‘‘rule of thumb’’ that alloys comprised of big atoms and little atoms tend to order into simple stuctures.

The Interaction Between Dislocations And Intergranular Cracks, H. Zhang, Alexander H. King, R. Thomson

Alexander H. King

The elastic interactions of dislocations and intergranular cracks in isotropic materials have been studied. In the first part of the paper, a model based on the Rice–Thomson theory is established under which the conditions for dislocation emission and crack propagation can be described in terms of an emission surface, cleavage surface, and loading line in the local k-space associated with a mixed mode intergranular crack. For a given crack, the local k-field changes with the emission of dislocations from the crack tip, which alters the balance of cleavage and emission. In the second part, we present experimental results of in …

Effect Of Hydration And Dimerization Of The Formamidine Rearrangement, Kiet A. Nguyen, Mark S. Gordon, Donald G. Truhlar

Mark S. Gordon

Ab initio molecular orbital theory is used to predict the geometry of the transition state and the energy barrier for the double-proton transfer in formamidine dimer, using SCF /6-31 G(d,p) and MP2/6-31 G(d,p) wave functions, respectively. Intramolecular hydrogen transfer in the uncomplexed monomer (I) and double-proton transfer in the mixed dimer of formamidine and water (2) are also investigated at several levels of theory. All computational levels predict the barrier for the uncomplexed reaction (I) to be approximately twicdhat for the hydrated reaction (2). Isomerization by double-proton transfer in the dimer (3) is predicted to be the most favorable process. …

Experimental Studies Of Fe-Mg Carbonates As Indicators Of Martian Near-Surface Conditions, Andrea Koziol

Andrea M. Koziol

Critical Properties Of A Randomly Driven Diffusive System, Beate Schmittmann, R. K. P. Zia

Beate Schmittmann

We consider a system of interacting particles, diffusing under the influence of both thermal noise and a random, external electric field which acts in a subspace of m dimensions. In the nonequilibrium steady state, the net current is zero. When the interparticle interaction is short ranged and attractive, a second-order phase transition is expected. Analyzing this system in field-theoretic terms, we find the upper critical dimension to be 4-m and its behavior to fall outside the universality classes of the equilibrium Ising model and the usual driven diffusive system. A new fixed point and critical exponents are computed.

Cluster As Solitons On The Nuclear Surface, Andrei Ludu

Andrei Ludu

No abstract provided.

The T-Designs On 13 Points With A Primitive Group Of Order 78 As A Group Of Automorphism, M. R. Darafsheh, M. Rajabi Tarkhorani, Saeid Abbasbandy

Saeid Abbasbandy

No abstract provided.

A Software World, David Morgan Lochhead

Dr. David Morgan Lochhead

What are the consequences when software defines reality? This essay was prepared for presentation at a church related computer event in 1991, but was never presented after the event was cancelled

Estimating County Percentages Of People Without Health Insurance, Paula Diehr

Paula Diehr

County data on the percentage of people without health insurance are seldom available, although state program planning requires such information. As part of an evaluation of Washington's Basic Health Plan (BHP), we conducted a telephone survey in nine Washington counties to estimate the percentage of people under the age of 65 who were uninsured. We used regression analysis to estimate the percentage uninsured in a county as a function of the percentage unemployed. Two validation approaches yielded very good results, suggesting that the equation could be used to estimate the percentage uninsured in unsurveyed counties. The variation ranged from 15% …