Physical Sciences and Mathematics Commons^™

Electro-Optics Applications For Alleviating Emi/Emc/Emp Problems, George H. Baker, Walter H. Hardwick

George H Baker

No abstract provided.

Structure-Factor Measurements In 4he As A Function Of Density, Robert Hallock, H. N. Robkoff

Robert Hallock

Measurements of the structure factor S(k) for 4He are reported as a function of pressure at 1.67, 2.20, and 4.24 K from saturated vapor pressure to 25 atm. The liquid structure factor is seen to sharpen and increase in amplitude with an increase in pressure at each of the temperatures studied. Comparison is made to previous results obtained by the technique of neutron scattering as well as to the theoretical predictions of Chang and Campbell and of Whitlock et al. The pair correlation function g(r) is obtained from the liquid structure factor by means of a Fourier transform, and comparison …

Excited States And Photochemistry Of Saturated Molecules. X. Ab Initio Calculations On The Vertical States Of Methylsilane, Mark S. Gordon

Mark S. Gordon

The vertical excitation energies are investigated for singlet and triplet states of methylsilane. To analyze the importance of Rydberg functions and of both valence and Rydbergd functions, a sequence of ten different basis sets are considered in conjuction with a single excitation configuration interaction. It is found that all of the singlet states below the first ionization potential may be characterized as Rydberg states, while there is considerable valence character in some of the low‐lying triplets. If the valence s and p functions are represented reasonably well (e.g., with a split valence basis set), the role of valence d orbitals …

Self‐Consistent Molecular Orbital Methods. Xxiii. A Polarization‐Type Basis Set For Second‐Row Elements, Michelle M. Franci, William J. Pietro, Warren J. Hehre, J. Stephen Binkley, Mark S. Gordon, Douglas J. Defrees, John A. Pople

Mark S. Gordon

The 6‐31G* and 6‐31G** basis sets previously introduced for first‐row atoms have been extended through the second‐row of the periodic table. Equilibrium geometries for one‐heavy‐atom hydrides calculated for the two‐basis sets and using Hartree–Fock wave functions are in good agreement both with each other and with the experimental data. HF/6‐31G* structures, obtained for two‐heavy‐atom hydrides and for a variety of hypervalent second‐row molecules, are also in excellent accord with experimental equilibrium geometries. No large deviations between calculated and experimental single bond lengths have been noted, in contrast to previous work on analogous first‐row compounds, where limiting Hartree–Fock distances were in …

Thermodynamic Model For Tricritical Mixtures With Application To Ammonium, Miron Kaufman, Robert B. Griffiths

Miron Kaufman

Procedures are developed for using composition data in the three-phase region and variations of meniscus heights to determine the parameters needed to relate a classical thermodynamic model for fluid mixtures near tricritical points to actual experiments. In the case of the mixture ammonium sulfate + water + ethanol + benzene the result is a reasonably good fit to a variety of data, including light scattering measurements of intensity and correlation length. There is some evidence for deviations from the classical theory, but it is not unambiguous.

Infinite Susceptibility At High Temperatures In The Migdal-Kadanoff Scheme, Miron Kaufman, Robert B. Griffiths

Miron Kaufman

The Migdal-Kadanoff real-space renormalisation group scheme applied to the Ising and classical XY (and probably other) ferromagnetic models yields an infinite susceptibility at all temperatures above the critical temperature for a hypercubic lattice of dimension d > 2.

Measurement Of Synchrotron X-Ray Energies And Line Shapes Using Diffraction Markers, Juana Vivó Acrivos, S.S. P. Parkin, K. Hathaway, J. R. Reynolds, M. P. Klein, A. Thompson, D. Goodin

Juana Vivó Acrivos

Standard reference markers for accurate, reproducible synchrotron x-ray energies are obtained using a three Si crystal spectrometer. The first two crystals are in the monochromator and the third is used to obtain diffraction markers which monitor the energy. Then for any value of the glancing angle on the reference Si crystal the energy for the (333) diffraction must occur at 3/4 that of the (444) and 3/5 of that for the (555). This establishes for the first time an absolute synchrotron energy scale. Higher-order diffractions are used to determine excitation line profiles. We conclude that the use of reference diffractions …

Structural Properties Of Ideals, J. Baumgartner, A. Taylor, Stan Wagon

Stan Wagon, Retired

No abstract provided.

Y Expansion For Directed Lattice Animals, Anthony Day, T. Lubensky

Anthony Roy Day

No abstract provided.

Path-Integrals And The Wkb Approximation, Br Holstein, Ar Swift

Barry R Holstein

The WKB approximation is demonstrated to be formally identical to the semiclassical limit of the Feynman path integral propagator. In the limit that the path integral propagator is dominated by the classical particle trajectory, it is identical to the propagator calculated directly from WKB wave functions in the stationary phase approximation.

Effects Of Earthquake On Traditional Houses Of Kathmandu, Bhishna Bajracharya

Bhishna Bajracharya

Asymptotic Theory Of Perturbed General Disconjugate Equations, William F. Trench

William F. Trench

No abstract provided.

Book Review (Reviewing Bruce A. Ackerman & William T. Hassler, Clean Coal/Dirty Air (1981)), John C. Dernbach, Thomas Y. Au

John C. Dernbach

No abstract provided.

Cluster Analysis To Determine Headache Types, Paula Diehr

Paula Diehr

Cluster analysis was used to separate 726 headache patients into clusters of patients with similar symptoms. This was done to answer two questions: what "naturally occurring' groups of patients can be found? And how do these groups correspond to traditional headache types? When only two clusters were required, the best two clusters were tension and migraine-like. However, eight clusters could also be distinguished, and the migraine group then became very small. The clusters were tested for clinical interpretability by having 12 physicians name and prescribe treatment for the clusters. The suggested treatment was similar to what patients had actually received …

Centers Of Polymer Research; Polymer Science In Tokyo, Japan, Part I: Central Area, Otto Vogl, A. Nakajima

Otto Vogl

No abstract provided.

Reply (To "Comment On 'The Absolute Scattering Cross Section At50 Mhz Of Equatorial Electrojet Irregularities' By Farley Et Al." By N. D'Angelo), D. T. Farley, Bela G. Fejer

Bela G. Fejer

No abstract provided.

The Absolute Scattering Cross Section At 50 Mhz Ofequatorial Electrojet Irregularities, D. T. Farley, H. M. Ierkic, Bela G. Fejer

Bela G. Fejer

We have made carefully calibrated radar scattering measurements by using the large 50-MHz Jicamarca antenna. Typical results from the altitudes of maximum echo power for the vertically directed beam are σradar ∼1–2 × 10−10 m−1 for strong daytime electrojet conditions with type 1 irregularities present, with values a factor of 10 or so smaller during moderate conditions when only type 2 are observed. These cross sections, which are very large in comparison with those for incoherent scatter (σradar ≃5 × 10−18 m−1 for an electron density of 1011 m−3), are not nearly large enough, however, to cause pseudo-absorption events on …

Comment On Particle Mixing And Delta-I= 3/2 Terms In Non-Leptonic Weak Decays, Br Holstein

Barry R Holstein

A recent paper by Gusbin concludes that ΔI=3/2 terms in K→πη can substantially modify particle-mixing contributions to K+→π+π0. Using techniques which can successfully reproduce the experimental features of the K→ππ decays, we argue that this seems unlikely.

Exactly Soluble Ising Models On Hierarchical Lattices, Miron Kaufman, Robert B. Griffiths

Miron Kaufman

Certain approximate renormalization-group recursion relations are exact for Ising models on special hierarchical lattices, as noted by Berker and Ostlund. These lattice models provide numerous examples of phase coexistence and critical points at finite temperatures, including cases of continuously varying critical exponents and phase transitions without phase coexistence. The lattices are, typically, quite inhomogeneous and may possess several inequivalent limits as infinite lattices.

Implications Of Nuclear Parity Non-Conservation, Jf Donoghue, Br Holstein

Barry R Holstein

From recent developments in the area of nuclear parity nonconservation we extract evidence for (1) SU(3) /soft-pion breaking in weak pionic vertices, and (2) larger values of quark masses than have been used in previous evaluations of "penguin" matrix elements.

Effects Of Three Vesicular-Arbuscular Mycorrhizal Fungi On Sweetgum Seedlings From Nine Mother Trees, Richard C. Schultz, Paul P. Kormanik, William C. Bryan

Richard C. Schultz

Soil in microplots was infested with three vesicular-arbuscular (VA) symbionts then sown with seed of half-sib progeny from nine sweetgum mother trees. The VA treatments were Glomus fasciculatus, Glomus spp. (a mixture containing both Glomus mosseae and Glomus etunicatus), or a VA mixture of several fungi from the genera Glomus and Gigaspora. Before the seed was sown, all plots had calcium standardized and received an application of commercial fertilizer. During the growing season, NH4NO3 was applied to all plots in equal portions. Mycorrhizal seedlings with G. fasciculatus were slightly but not significantly larger in both height and root-collar diameter than …

Relative Stability Of Multiple Bonds To Silicon: An Ab Initio Study Of C2sih4 Isomers, Mark S. Gordon, Robert D. Koob

Mark S. Gordon

Ab initio (6-31G*/ /3-21G) SCF calculations have been carried out on 15 isomers with the chemical formula C2SiH4• The isomers include structures with formal double and triple bonds to silicon, as well as carbenes and silylenes, so a direct comparison of these types of species is possible. The isomerization energies provide an opportunity to consider the relative strengths of analogous bonds to carbon and silicon. With the appropriate isodesmic reactions, the stabilizing or destabilizing effects of substituents and strain in three-membered rings both may be investigated.

Structure And Stability Of A Silicon-Carbon Triple Bond, Mark S. Gordon, John A. Pople

Mark S. Gordon

The stability of the carbon-silicon triple bond in silaethyne is investigated via an analysis of its isomerization to silylidene and through a study of its hydrogenation energy relative to acetylene and silaethylene. It is found that silaethyne is rather unstable in a thermodynamic sense. However, while SCF calculations predict this species to rearrange to its more stable isomer with no barrier, the introduction of perturbation corrections suggests the existence of a small barrier separating the two isomers.

Direct Nmr Observation Of Rotational Freeze-Out In The Smectic C-Phase, Demetri J. Photinos, Philip J. Bos, Mary E. Neubert, J. William Doane

Philip J. Bos

We report here a simple and direct observation that the molecular long axis is not, on the average, a rotation axis for the entire molecule in the smectic C phase (rotational freeze-out). This observation is made in the compound 4-n-heptyl-d15-oxybenzoic acid-d1 where experiment clearly shows that the principal axes of the time-averaged deuterium quadrupole interactions at specific sites of the hydrocarbon chain are not all parallel, demonstrating that they do not share a common axis of rotation.

Three-Component Model And Tricritical Points: A Renormalization-Group Study., Miron Kaufman, Robert B. Griffiths, Julia M. Yeomans, Michael E. Fisher

Miron Kaufman

The global phase diagram for a three-component lattice gas or spin-one Ising model with general single-site and nearest-neighbor "ferromagnetic" interactions is worked out for twodimensional lattices using a Migdal-Kadanoff recursion relation. It differs in important qualitative respects from the corresponding mean-field phase diagram. The set of fixed points and flows provides the characteristic'phase diagrams of the three-state Potts multicritical point and the ordinary (n =1) tricritical point in a complete set of symmetry-breaking fields. The latter is associated, in this renormalization-group scheme, with seven distinct critical fixed points, a number which is surprisingly large.

Interferometer Studies Of Equatorial Fregion Irregularities And Drifts, E. Kudeki, Bela G. Fejer, D. T. Farley, H. M. Ierkic

Bela G. Fejer

A radar interferometer technique developed at Jicamarca, Peru and first used to study electrojet irregularities has now been used successfully to study plasma turbulence in the equatorial F region. Our first results have shown that the most ‘turbulent’ echoes appear to come from a region that extends for tens of kilometers in altitude but for only a kilometer or less in the east-west direction. This slab may very well be the wall of a depleted region, a plasma ‘bubble’. Sometimes the irregularities can be tracked as they move eastward or westward. Velocity profiles for the evening period obtained in this …

Induced Tensor And Ft Asymmetries, Br Holstein

Barry R Holstein

Looked at from a model-independent point of view, the existence of a non-zero first class induced tensor form factor appears to provide a substantial contribution to the observed ft asymmetry in mirror Gamow-Teller beta decays. However, we demonstrate that, when analyzed in terms of the impulse approximation, this is only a negligibly small effect. RADIOACTIVITY Calculated contribution to ft asymmetry from first class induced tensor.

Radar Interferometry: A New Technique For Studyingplasma Turbulence In The Ionosphere, D. T. Farley, H. M. Ierkic, Bela G. Fejer

Bela G. Fejer

A new radar interferometer technique has been developed and used successfully at the Jicamarca Radio Observatory in Peru to study the strong nighttime plasma turbulence in the equatorial electrojet. The technique represents a major step forward in radar probing of turbulent irregularities such as (but not limited to) those in the electrojet. In many situations it provides far more information than previous Doppler measurements. We form the cross spectrum of the backscattered signals received from approximately overhead on two antennas, separated in this case along an east-west baseline, as well as the individual power spectra. From the phase of the …

Compendium Of Bag-Model Matrix-Elements Of The Weak Non-Leptonic Hamiltonian, Jf Donoghue, E Golowich, Br Holstein, Wa Ponce

Barry R Holstein

A comprehensive list of baryon and meson single-particle matrix elements of the nonleptonic weak Hamiltonian is presented.

Acute Headaches; Presenting Symptoms And Diagnostic Rules To Identify Patients With Tension And Migraine Headache , Paula Diehr

Paula Diehr

Headache is the ninth most common cause of physician visits, but data on acute headaches have not been collected in a standardized manner and have not been analyzed in a multivariate fashion. We report on 726 patients presenting with acute headaches, which were diagnosed as tension (38%), migraine (25%), no diagnosis (30%), and other (6%). The prevalence of 32 signs and symptoms is shown for each group. Four of these findings were significant predictors of tension headache, and 19 were significant predictors of migraine headache (p<.05). Several diagnostic rules are developed which classify nearly 90% of the headaches correctly, using only three to seven of the findings. On a new set of patients the classification was correct over 80% of the time. It is suggested that most acute headaches could be diagnosed over the telephone or by midlevel providers, which would provide substantial cost savings.