Physical Sciences and Mathematics Commons^™

Ground-State Potential Energy Surface Of Phosphine Oxide, Jerry A. Boatz, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

A network of elimination reactions of H3PO in its ground state is examined by using ab initio (3-21G* and 6-31G** with MP3 perturbation corrections) wave functions. In addition to the eliminations, several isomerizations and internal rotations of the parent compound and its fragments are investigated. The insertion and reactive scattering reactions of H2 + HPO, which are characterized more fully with MP4(SDTQ) perturbation corrections, are followed by using the intrinsic reaction coordinate and energy-localized orbitals.

Insertion Of Methylene Into Ethane And Cyclopropane, Mark S. Gordon, J. A. Boatz, David R. Gano, Marie G. Friederichs

Mark S. Gordon

The insertions of methylene into the CH and CC bonds of ethane and into a CC bond of cyclopropane are calculated by using third-order perturbation theory with the 6-31G(d) basis set. At this level of theory, the barriers for these reactions are predicted to be 0.2, 46.0, and 2.2 kcaljmol, respectively. Thus, the introduction of strain has a dramatic effect on the barrier to insertion into a heavy atom-heavy atom bond.

Case Studies Of Human-Forest Interactions In Northeast Thailand, James Hafner

James A Hafner

Ludicene Cream Face With Herbal Ingredients?, Ludicene Cream

Ludicene Cream

Potential Energy Surfaces For Polyatomic Reaction Dynamics, Donald G. Truhlar, Rozeanne Steckler, Mark S. Gordon

Mark S. Gordon

The last few years have seen an explosive growth of interest in detailed studies of polyatomic reaction dynamics. Improved experimental techniques, more powerful semiclassical dynamical methods, and accurate electronic structure capabilities have all combined to focus attention on detailed dynamical questions for larger and larger systems. Many of these questions have previously been tackled primarily for atom-diatom or diatom-diatom collisions or isolated triatomics. 1- 5 Although of course the final word on such simpler systems has not been said (and never will be), we will focus in the present review on more complicated cases. Thus the "polyatomic" in the title …

Kobayashi-Maskawa Angles And Su(3) Breaking In Hyperon Beta-Decay, Jf Donoghue, Br Holstein, Sw Klimt

Barry R Holstein

The determination of the Kobayashi-Maskawa matrix element Vus from hyperon β decays has long had a hidden uncertainty due to the almost universal assumption of SU(3) invariance in Cabibbo-type fits, especially since the data definitely indicate the presence of SU(3) breaking. We have reanalyzed the hyperon-decay data using the pattern of symmetry breaking predicted by the quark model including the center-of-mass correction. We find that the SU(3)-broken picture is far superior to the assumption of perfect SU(3), and provides a good fit to experiment. The sensitivity of Vus to the breaking is not large and we find Vus=0.220+/-0.001+/-0.003 (the errors …

Human-Forest Interactions In Northeast Thailand, James A. Hafner Professor Emeritus

James A Hafner

Implications Of Atmospheric Test Fallout Data For Nuclear Winter, George H. Baker

George H Baker

Atmospheric test fallout data have been used to determine admissible dust particle size distributions for nuclear winter and nuclear fallout studies. The research was originally motivated by extreme differences noted in the magnitude and longevity of dust effects predicted by particle size distributions routinely used in fallout predictions versus those used for nuclear winter studies. Three different sets of historical data have been analyzed:

1. Stratospheric burden of Strontium-90 and Tungsten-185, 1954-1967 (97 contributing events) 2. Continental U.S Strontium-90 fallout through 1958 (75 contributing events) 3. Local Fallout from selected Nevada tests (16 events)

The contribution of dust to possible …

First Integrals For Equations With Nonlinearities Of The Emden-Fowler Type, William Trench, Leon Bahar

William F. Trench

No abstract provided.

Characteristic Polynomials Of Symmetric Rationally Generated Toeplitz Matrices, William Trench

William F. Trench

No abstract provided.

Fish Acute Toxicity Syndromes And Their Use In The Qsar Approach To Hazard Assessment, Steven P. Bradbury, James M. Mckim, Gerald J. Niemi

Steven P. Bradbury

Implementation of the Toxic Substances Control Act of 1977 creates the need to reliably establish testing priorities because laboratory resources are limited and the number of industrial chemicals requiring evaluation is overwhelming. The use of quantitative structure activity relationship (QSAR) models as rapid and predictive screening tools to select more potentially hazardous chemicals for in-depth laboratory evaluation has been proposed. Further implementation and refinement of quantitative structure-toxicity relationships in aquatic toxicology and hazard assessment requires the development of a "mode-of-action" database. With such a database, a qualitative structure-activity relationship can be formulated to assign the proper mode of action, and …

Physiological Response Of Rainbow Trout (Salmo Gairdneri) To Acute Fenvalerate Lntoxication, Steven P. Bradbury, James M. Mckim, Joel R. Coats

Steven P. Bradbury

The physiological responses of rainbow trout (Salmo gairdneri) to fenvalerate intoxication during aqueous exposure were examined to provide information about the pyrethroid mode of action in fish. Trout (n = 4) were exposed to 412 ± 50 μg/liter fenvalerate and died in 10.9 ± 1.5 hr. Brain, liver, and carcass fenvalerate concentrations associated with mortality were 0.16 ± 0.05, 3.62 ± 0.57, and 0.25 ± 0.05 mg/kg, respectively. Visible signs of intoxication included elevated cough rate, tremors, and seizures. Histopathological examination of gill tissue showed damage consistent with irritation. An evaluation of respiratory-cardiovascular and blood chemistry responses indicated an elevated …

Spatial And Temporal Analysis Of 1200 Landslides In A 900km2 Area, Middle Rocky Mountains, Wyoming, U.S.A., James P. Mccalpin

James P. McCalpin

An inventory of approximately 1200 landslides in a 900 km2 area in the Salt River Range, western Wyoming, U.S.A., reveals regional and temporal controls on the landsliding process. Sliding is strongly controlled by eight weak formations in the 21 stratigraphic units of Cambrian through Cretaceous age. Morphologic dating of slides suggests that rockslides, slump-flows, and debris flows have occurred rather uniformly in time within the Holocene. In contrast, earthflows seem to be triggered more by cool/wet climatic epicycles in the last 5,000 years.

Field Trip Roadlog For The Bear River Landslide Complex, James P. Mccalpin

James P. McCalpin

The Bear River Landslide Complex occurs where the unconsolidated sediments of the Bear River Delta have been incised to a depth of 350 to 490 feet (106-150 m) north of Preston, Idaho. The slides are the result of the high pore pressure in confined aquifers in the deltaic sediments. High but variable volumes of groundwater flow and the laterally discontinuous nature of the deltaic sediments result in the varied types of earth movements found within the Landslide Complex. Landslide activity occurs during years of above average precipitation, and has been exacerbated by increased recharge from reservoirs and irrigation canals constructed …

Recommended Setback Distances From Active Normal Faults, James P. Mccalpin

James P. McCalpin

The geometry of near-surface ground breakage was analyzed from 40 trenches across Quaternary normal faults to help define reasonable setback distances. From each of the trench logs (28 on the Wasatch Fault, 11 on other Great Basin faults) eight parameters characteristic of surface rupture style were measured. Parameters included: 1) position of the main fault in relation to scarp morphology. 2) dip of the main fault. 3) number of faults on the upthrown block, 4) width of the upthrown block fault zone. 5) number of faults in the downthrown block. 6) width of the downthrown deformation zone, 7) ratio of …

The Bear River Landslide Complex, Preston, Idaho: Geologic Considerations And Historical Perspectives, James P. Mccalpin

James P. McCalpin

The Bear River Landslide Complex is a series of earth movements in northern Cache Valley, north of Preston, Idaho. The landslides occur in unconsolidated sediments of the Pleistocene Bear River Delta which formed where the river entered Lakes Bonneville and Provo. The Lake Bonneville delta deposits are up to 490 feet (150 m) thick and consist of a lower alluvial coarse sand and gravel unit, a middle delta front fine sand and silt unit, and an upper pro-delta clay up to 50 feet (15 m) thick. The interbedded character of the fine sands, silts, and clays, together with abrupt lateral …

The Further Geometry Of Grain Boundaries In Hexagonal Close-Packed Metals, Fu-Rong Chen, Alexander H. King

Alexander H. King

A technique is given for finding partial DSC vectors appropriate to crystals with more than one atom per lattice site. The DSC lattice is made up of vectors that represent displacements of one crystal with respect to the other that leave the boundary structure shifted, but not complete. A new, rapid method for finding the step vectors associated with perfect DSC dislocations is described. Partial DSC vectors and step vectors for perfect DSC dislocations in hexagonal close-packed crystals are determined. The availability of reactions between lattice partial dislocations and grain boundaries in hexagonal close-packed crystals is also assessed.

Interaction Between Magnetic And Compositional Order In Ni‐Rich Ni C Fe1−C Alloys (Invited), J. B. Staunton, Duane D. Johnson, B. L. Gyorffy

Duane D. Johnson

We have developed a first‐principles electronic theory of concentration fluctuations in spin polarized binary alloys. It is a mean field theory of the state of compositional order and it is based on the local spin density (LSD) approximation for describing the electrons. The usual averages over the statistical mechanical ensemble are carried out with the aid of the self‐consistent Korringe–Kohn–Rostoker coherent‐potential approximation (SCF‐KKR‐CPA). To illustrate the main consequences of the theory we study the compositional short‐range order in the Ni c Fe1−c alloy system. We find that the ordering energy is almost entirely of magnetic origin.

Radiation And Cloud Observations On A High Arctic Plateau Ice Cap, M. C. Serreze, Raymond S. Bradley

Raymond S Bradley

Hourly measurements of incoming short-wave and long-wave radiation, surface albedo, and net radiation were made on and around a plateau ice cap on north-eastern Ellesmere Island during the summers of 1982 and 1983. These data were stratified by cloud type and amount. All cloud types increased incoming long-wave radiation, especially low dense clouds, fog, and clouds associated with snowfall. Relative transmission of incoming short-wave radiation, expressed as a percentage of clear-sky radiation receipts, was high for all cloud types compared to clouds at lower latitudes. With high surface albedo (~0.75), net radiation was strongly and positively correlated with net long-wave …

Mass Balance Of Two High Arctic Plateau Ice Caps, Raymond S. Bradley, Mark C. Serreze

Raymond S Bradley

Mass-balance measurements have been renewed on two small ice caps on north-eastern Ellesmere Island. Original stake networks were established in 1972 and 1976. Since then, both ice caps have experienced significant mass losses averaging -70 to -140 kg m- 2 a-I. They have also decreased in area. The equilibrium line in this area has averaged around 1150 m for the last decade or so. 'The ice caps are remnants of former climatic conditions and are out of equilibrium with contemporary climate.

Topoclimatic Studies Of A High Arctic Plateau Ice Cap, Raymond S. Bradley, Mark C. Serreze

Raymond S Bradley

Meteorological observations on and around a small, exposed plateau ice cap on north-eastern Ellesmere Island, N.W.T., Canada, were carried out in the northern summers of 1982 and 1983. The objective was to assess the effect of the ice cap on local climate as the melt season progressed. In 1982, seasonal net radiation totals were lowest on the ice cap and greatest at the site farthest from the ice cap. The ice-cap site received only 35% of net radiation totals on the surrounding tundra. This reflects a gradient in albedo; albedo changed most markedly away from the ice cap as the …

Estimating The Value Of Water Quality Improvements In A Recreational Demand Framework, Nancy E. Bockstael, Catherine Kling, W. Michael Hanemann

Catherine Kling

With the advent of Executive Order 12291, policymakers involved in water quality regulation are increasingly interested in assessing the benefits of their programs. Several methods for valuing water quality improvements using recreational demand models have been developed by economists, most of which depend on observing recreationists visiting an array of sites with varying water quality and costs of access. In this paper, three general types of models are described: systems of demands, discrete choice models, and the hedonic travel cost approach; the latter two models are demonstrated using a common data set on water quality and swimming behavior in 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.

Esr Study Of Optically Induced Phase Transitions, Juana Vivó Acrivos, H. P. Hughes, S. S.P. Parkin

Juana Vivó Acrivos

We have identified an optically enhanced magnetic phase transition in the newly synthesized organic molecular charge transfer salt, (BEDT-TTF)3Ta2F11 (BEDT-TTF bisethylenedithiolotetrathiafulvalene) by ESR absorption measurements in the X band microwave region. At room temperature, only a doublet state ESR absorption is observed, but below 30 K severa~ tripl~t E.SR absorpti_ons appear. The orientation dependence of the ESR absorption under lllummat10n at energies near the band gaps in the material ( 640 nm, T = 12 to 5 K H0 < 0.34 T) indicates that there are rapid spin exchange processes with times r < w-s; near 7 ~o 5 K.along cert~in ~rystallographic directions with a temperature dependen~e suggesting spm-lattlce relaxation times which proceed via Van Vleck "direct processes." This, to our knowledge, is the first case where the magnetic properties of a charge transfer salt are altered by the interaction with photons of energy equal to the band gaps in a low dimensional solid providing a new, interesting way to investigate these materials.

Higher-Dimensional Self-Consistent Solution With Deformed Internal Spaces, T. -C. Shen, J. Sobczyk

T. -C. Shen

We study a system of gravity and free massless scalar fields minimally coupled to gravity in a 7- dimensional background which is a direct product of a 4-dimensional Minkowski space and a 3- dimensional homogeneously deformed three-sphere. Compactification is caused by the vacuum energy of scalar fields. The effective potential as a function of two parameters (scale and deformation) is calculated numerically after dimensional regularization. We find the effective potential decreases rapidly toward negative infinity in both prolate and oblate directions. The classical curvature, however, can balance the quantum effect and yields three extrema. In addition to the round S …

Primary And Secondary Basis Set Superposition Error At The Scf And Mp2 Levels. H3n‐‐Li+ And H2o‐‐Li+, Zdzisław Latajka, Steve Scheiner

Steve Scheiner

The primary basis set superposition error (BSSE) results from the artificial lowering of the energy of each subunit of a pair by the presence of ‘‘ghost orbitals’’ of its partner. In addition, these ghost orbitals perturb the one‐electron properties of the molecule, causing a change in the interaction energy, an effect known as secondary BSSE which is not corrected by the counterpoise procedure. The primary and secondary BSSE are calculated for the interactions of NH₃ and H₂O with Li⁺, using a variety of different basis sets. It is found that the 2° BSSE can be …

Vibrational Frequencies And Intensities Of H-Bonded Systems. 1:1 And 1:2 Complexes Of Nh3 And Ph3 With Hf, I. J. Kurnig, M. M. Szczesniak, Steve Scheiner

Steve Scheiner

Frequencies and intensities are calculated by ab initio methods for all vibrational modes of the 1:1 H₃X–HF and 1:2 H₃X–HF–HF complexes (X=N,P). The HF stretching frequencies are subject to red shifts, roughly proportional to the strength of the H bond, and to manyfold increases in intensity. Although the intramolecular frequency shifts within the proton acceptors are relatively modest, the intensities of the NH₃ stretches are magnified by several orders of magnitude as a result of H bonding (in contrast to PH₃ which exhibits little sensitivity in this regard). …

Simple Scheme For Variable High Power Laser Beam Attenuation, Stephen E. Bialkowski

Stephen E. Bialkowski

A venetian style infrared attenuator placed prior to a pinhole spatial filter results in variable high‐power laser attenuation. This attenuation scheme has a wide dynamic range, results in high‐quality Gaussian beams, does not introduce beam walk‐off error, and is independent of polarization.

Optimal Estimation Of Impulse‐Response Signals Through Digital Innovations And Matched Filtersmoothing, Stephen E. Bialkowski

Stephen E. Bialkowski

A real‐time digital filter is described which may be most useful for optimal determination of the magnitude of impulse‐response functions found in pulsed, repetitive experiments of low duty cycle. This filter is based on a matched filter but employs an interference orthogonalization step. This results in a signal magnitude estimate which is independent of coherent interference. The filter updates the signal magnitude estimate upon each repetition of the experimental cycle. Comparisons to signal estimation using gated sampling devices are given.