Physical Sciences and Mathematics Commons^™

Ethno-Botany. Field Notes Nature Documentaries, Nat Quansah

Nat Quansah

No abstract provided.

Resistivity Of The High-Temperature Metallic Phase Of Vo2, Werner W. Schulz, Philip B. Allen, Renate M. Wentzcovitch, Paul C. Canfield

Paul C. Canfield

Measurements are reported on the electrical resistivity ρ(T) along the c axis of a single crystal of VO2, from the metal-insulator transition at T=333 K up to 840 K. The temperature dependence is very linear, and a fit to Bloch-Grüneisen theory gives a residual resistivity ρ0=65 μΩ cm and a ratio ρ(840 K)/ρ0=8. With the help of a local-density-approximation band-structure calculation, we further pursue the conventional (Bloch-Boltzmann) interpretation by extracting the electron-phonon coupling constant λ=1.1 and the mean free path l(800 K)=3.3 Å. The short mean free path implies that the conventional interpretation is internally inconsistent. The most likely explanation …

Does Methane Invert Through Square Planar?, Mark S. Gordon, Michael Schmidt

Mark S. Gordon

MCSCF calculations using a triple-t basis set augmented with diffuse and polarization functions are used to probe that part of the singlet methane potential energy surface that pertains to the inversion of CH4 from one t~trahedral structure t.o another. The true inversion transition state is found to have a distorted C, structure, quite different both ge?me.tncally ~nd energetically from the previously presumed square planar saddle point. At the secondorder configuration mte.ractl~n.level of theory, the barrier to inversion is predicted to be just 7-8 kcaljmol higher in energy than the bond diSSOCiation energy for the first C-H bond cleavage in methane.

Three-Point Correlation Functions In Uniformly And Randomly Driven Diffusive Systems, K. Hwang, Beate Schmittmann, R. K. P. Zia

Beate Schmittmann

Driven far away from equilibrium by both uniform and random external fields, a system of diffusing particles with short-range attractive forces displays many singular thermodynamic properties. Surprisingly, measuring pair correlations in lattice-gas models with saturation drives, we find little difference between the uniform and random cases, even though the underlying symmetries are quite distinct. Motivated by this puzzle, we study three-point correlations using both field-theoretic and simulation techniques. The continuum theory predicts the following: (a) The three-point function is nonzero only for the uniformly driven system; (b) it is odd under a parity transformation; and (c) there exists an infinite …

Polymer Science In Austria Iii, Universities In Linz, Innsbruck And Other Research Institute In Austria Including Industry, Otto Vogl, Josef Schurz

Otto Vogl

No abstract provided.

Composite, Large Spirochetes From Microbial Mats: Spirochete Structure Review, Lynn Margulis, J. B. Ashen, M. Solé, R. Guerrero

Lynn Margulis (1938 - 2011)

Phenomena previously unknown in free-living spirochetes are reported: large-sized cells with variable diameter (length to 100 microns, width between 0.4 and 3.0 microns), composite structure (smaller spirochetes inside larger ones), and positive phototropic behavior. These bacteria, Spirosymplokos, are compared with all other spirochete genera. The large spirochete, grown in mixed culture, was studied live and by transmission EM. The protoplasmic cylinder was replete with spherical granules 20-32 nm in diameter, and three to six periplasmic 26-nm flagella were inserted subterminally. Comparably granulated and flagellated small spirochetes were located inside the protoplasmic cylinder and in the periplasm of the large ones. …

Transverse Form Factors Of 117sn, H Baghaei, J Dubach, M B. Frodyma, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

Transverse elastic and inelastic form factors for low-lying levels in 117Sn have been measured by 180° electron scattering in the momentum transfer range qeff=1.1–2.4 fm-1. The simple independent-particle model fails to account for these data, predicting form factors that are much too large. In better quantitative agreement with the data are the results of more detailed calculations that allow for configuration mixing of valence nucleons, as well as first-order core polarization. As in the similar case of 205Tl, these calculations successfully predict the presence of a deep diffraction minimum observed in the intermediate q region of the elastic M1 form …

Apparent And True Feature Heights In Force Microscopy, Nancy Burnham

Nancy A. Burnham

In a force microscope, the stiffness of the cantilever beam convolutes with the tip‐sample interaction stiffness to influence the data in a systematic way. The analysis presented here relates the measured feature height to the true feature height in the variable force, constant force, and constant force gradient modes of operation. In this way, one can understand previously published data: the enhanced measured atomic corrugation observed in high resolution force microscopy images, its increase with load, and the improved resolution of lateral force images. The correct interaction stiffness can be obtained for use in surface force and mechanical properties studies. …

H I Streamers Around M82 - Tidally Disrupted Outer Gas Disk, Min S. Yun, Paul T P Ho, K Y. Lo

Min S. Yun

Our new VLA observations of M82 reveals a triangular central concentration of neutral atomic gas and several more than about 10 kpc long tidal streamers originating from M82 itself. The coincidence of the beginning of the tidal streamer with the flaring of the optical disk as well as the smooth continuation of the disk velocity field into the H I streamer strongly suggest the tidal disruption of the disk of M82, contrary to the widely proposed scenario of tidal stripping and gas accretion from its neighbor M81. The velocity characteristics of H I within M82 are that of disk rotation …

Hexameric Lithium Phenolate: Crystal Structures And Lithium-7 Quadrupole Coupling In Solid And Solution Phases., Lloyd Jackman, Deniz Cizmeciyan, Paul Willard, Michael Nichols

Michael A Nichols

No abstract provided.

Experimental And Computational Studies Of Four-Coordinate Aluminum: The Reaction Of Aluminates And Acids, Robert Damrauer, Michèle Krempp, Niels H. Damrauer, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

The gas-phase reactions of trimethylaluminates with a variety of acids are considered from both an experimental and computational perspective. The experimental work involves product and kinetic studies of ten aluminates, [(CH3hAlX]- (X= H, CH3, NH2, OH, F, SiH3, PH2, SH, Cl, and OCH3). Both X and methyl cleavage pathways are observed in these reactions. X cleavage occurs with several aluminates (X = H, NH2, OH, and PH2), in contrast to the thermochemical predictions of ab initio computations performed at the MP2/6-31 ++G(d,p) level. These indicate that methyl cleavage is favored in the reaction of nine aluminates (OCH3 was not computed) …

Ground-State Magnetization Density Of 89y, J E. Wise, J R. Calarco, J P. Connelly, S A. Fayans, F W. Hersman, J H. Heisenberg, R S. Hicks, W Kim, T E. Milliman, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

Elastic electron scattering cross sections have been measured for 89Y at 180° for 0.72

Recent Changes In The North American Arctic Boundary Layer In Winter, Raymond S. Bradley, Frank T. Keimig, Henry F. Diaz

Raymond S Bradley

Analysis of significant level radiosonde data from a network of Arctic stations reveals a systematic reduction in midwinter surface-based inversion depths over the past few decades, accompanied by a rise in surtace temperature. Similar trends are observed over a wide sector, from 62°W to 162°W and from 700N to 83°N. Possible causes for these changes include increases in warm air advection, cloud cover, ice crystals, aerosols, and greenhouse gases, but the specific reasons are difficult to identify, due to strong interactions between many potentially important factors. Nevertheless, the changes are significant for studies of Arctic haze, since the midwinter stable …

Small Area Variation Analysis. Methods For Comparing Several Diagnosis-Related Groups., Paula Diehr

Paula Diehr

In small-area variation analysis, the variation of health care utilization rates, e.g., admission rates, among small areas is calculated. Frequently, the variation of one diagnosis, diagnosis-related group (DRG), or procedure is compared with the variation of another. Unfortunately, the methods generally used to make these comparisons are not consistent. They differ on whether they 1) adjust for the prevalence of the DRGs, 2) distinguish between variation among areas and variation within areas, 3) weight all areas equally, and 4) adjust for multiple admissions per person. None has an associated confidence interval. These discrepancies occur in part because there is no …

Building Madagascar’S Capacity In Medicinal Plants Research: Training In Ethno-Pharmacology And Phytochemistry, Nat Quansah

Nat Quansah

No abstract provided.

Are Spread Out Cities Really Safer? , Michael E Lewyn

Michael E Lewyn

One of my first articles. A discussion of the gap between perceptions of crime and the reality of crime, noting that sprawling Sun Belt cites were erroneously perceived as safer than they really were, while older, denser northern cities were erroneously perceived as more dangerous.

Generalized Linear Models: Software Implementation And The Structure Of A General Power-Link Based Glm Algorithm, Joseph Hilbe

Joseph M Hilbe

Generalized linear modeling (GLM) is currently undergoing a renaissance. The number of software packages offering GLM capability grows each year and as a partial consequence one finds an increased number of research endeavors being modeled using GLM methodology. On the other hand, there have likewise been an increasing number of requests to vendors by users of statistical packages to include GLM facilities amid other offerings. The overall effect has been a near 300 percent increase in GLM programs over the past four years.

I shall discuss the nature of generalized linear models followed by an examination of how they have …

Tensor Operators Iii, Some Fundamental Tensor Operator Identities, Daniel Flath, J. Towber

Daniel Flath

No abstract provided.

Measurements Of Transverse Electron Scattering From The Deuteron In The Threshold Region At High Momentum Transfers, M Frodyma, R G. Arnold, D Benton, P E. Bosted, L Clogher, G Dechambrier, A T. Katramatou, J Lambert, A Lung, G G. Petratos, A Rahbar, S E. Rock, Z M. Szalata, B Debebe, R S. Hicks, A Hotta, Gerald Alvin Peterson

Gerald Alvin Peterson

Deuteron electrodisintegration cross sections near 180' have been measured near breakup threshold for the four-momentum transfer squared Q' range 1.21—2.76 (GeV/c) . Evidence for a change of slope in the cross section near Q =1 (GeV/c ) has been obtained. The data are compared to nonrelativistic calculations, which predict a strong influence of meson-exchange currents. The data are also compared to a hybrid quark-hadron model ~ None of these calculations agrees with the data over the entire measured range of Q'. The ratio of inelastic structure functions W, (Q', E„~)/Wz(Q', E„~)is extracted from the present results and previous forward angle …

Quantitative Determination Of Surface Excess By The Semiintegral Method, Susanne Dana, Mathew Jablonski, Mark Anderson

Mark R. Anderson

In 1988 Bowling and McCreery reported that the semiintegral of voltammetric data provided an excellent method for the qualitative diagnosis of weak adsortpion of material upon an electrode. This report was important to electroanalytical chemistry because of the difficulty often encountered when trying to identify the presence of weakly adsorbed material and because of the impact that weak adsorption has upon voltammetric response. Many electrochemical analyses are dependent upon the evaluation of voltammetric wave shape, particularly kinetic analyses. Unlike strong adsorption, the presence of weakly adsorbed material does not dramatically and obviously perturb the shape of the voltammetric response; consequently, …

Interim Report On Data And Methods For Assessment Of 2,3,7,8-Tetrachlorodibenzo-P-Dioxin Risks To Aquatic Life And Associated Wildlife, Steven P. Bradbury, Philip M. Cook, Russell J. Erickson, Robert L. Spehar, Gerald T. Ankney

Steven P. Bradbury

In April, 1991 the Administrator of the U.S. Environmental Protection Agency (EPA) announced that the Agency would conduct a scientific reassessment of the risk of 2,3,7,8-tetrachlorodibenzo-p-dioxin (hereafter referred to as TCDD), and similar chemicals, to human health and the environment. Since 1985, EPA has classified TCDD, which it considers the most potent known animal carcinogen, as a probable human carcinogen. Sources of TCDD in the environment were subsequently regulated on the basis of animal cancer rates extrapolated to doses associated with human exposures. Recently, consensus has developed that the toxic effects of TCDD appear to be mediated by its binding …

Microscale-Liquid Chromatographic Determination Of Pungent Compounds, Maha Khaled, Mark Anderson, L. Marquez, Harold Mcnair

Mark R. Anderson

No abstract is currently available.

Strength Of Bentonite Water-Well Annulus Seals In Confined Aquifers, Fred Ogden

Fred L. Ogden

The advantages of bentonite clay for sealing applications are well known. Bentonites have extremely low permeability, do not affect formation water chemistry, and have the ability to swell and deform in response to subsurface changes. The major limitation on the applicability of bentonite for water well annulus sealing is strength. Strength tests conducted in a physical model of a water well identified the expected magnitude of shear strength for several commercially available bentonite well-sealing products. The dependence of bentonite strength in the annulus of a water well on both setting time and borehole geometry is discussed. Force balance calculations for …

Solid-State Structures Of N-Butyllithium-Tmeda, -Thf, And -Dme Complexes., Michael Nichols, Paul Williard

Michael A Nichols

No abstract provided.

Use Of Infrared Spectroscopy To Probe Analytical Surfaces, Mark Anderson

Mark R. Anderson

No abstract is available at this time.

Use Of Infrared Spectroscopy To Probe Analytical Surfaces, Mark Anderson

Mark R. Anderson

No abstract is available at this time.

Measurements Of The Electric And Magnetic Form Factors Of The Neutron From Q2=1.75 To 4.00 (Gev/C)2, A Lung, L M. Stuart, P E. Bosted, L Andivahis, J Alster, R G. Arnold, C C. Chang, F S. Dietrich, W R. Dodge, R Gearhart, J Gomez, K A. Griffioen, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson

Gerald Alvin Peterson

Quasielastic e-d cross sections have been measured at forward and backward angles. Rosenbluth separations were done to obtain RL and RT at Q2=1.75, 2.50, 3.25, and 4.00 (GeV/c)2. The neutron form factors GEn and GMn have been extracted using a nonrelativistic model. The sensitivity to deuteron wave function, relativistic corrections, and models of the inelastic background are reported. The results for GMn are consistent with the dipole form, while GEn is consistent with zero. Comparisons are made to theoretical models based on vector meson dominance, perturbative QCD, and QCD sum rules, as well as constituent quarks.

Insertion Reactions Of Monovalent Silicon: A Nonvanishing Barrier For The Silylidyne Plus Hydrogen Reaction Sih + H2, Mark S. Gordon, Yaoming Xie, Yukio Yamaguchi, Roger S. Grev, Henry F. Schaefer Iii

Mark S. Gordon

Ab initio quantum mechanical methods have been applied to the SiH (X zrr) insertion into the Hz molecule. The transition state has no elements of symmetry. The classical barrier height is predicted to be 5.6 :I: I kcaljmol. The barrier is qualitatively consistent with an estimate from Jasinski's experimental reaction rates, which are much slower than those observed for the related CH + Hz, SiH + SiH4, and SiH2 + Hz reactions.

Burnham, Colton, And Pollock Reply, Nancy Burnham, Rj Colton, Hm Pollock

Nancy A. Burnham

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 3.0 License. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author (s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder

Special Review: Evaluation Of The Exploratory Factor Analysis Programs Provided In Spssx And Spss/Pc+, Gregory J. Boyle

Gregory J. Boyle

Given the frequent use of SPSSX and SPSS/PC+ exploratory factor analysis in analyzing multivariate psychometric data, it is germane to examine the limitations of the Factor program as it currently exists. Over recent years, the routines in these packages generally have been developed and expanded considerably. In particular, the exploratory factor analysis procedures have been greatly extended and enhanced with inclusion of additional estimation methods such as minimum likelihood, unweighted least squares, generalized least squares, and so on. Like­ wise, availability of a Scree plot of the latent roots against factor number has facilitated determination of the appropriate factor-extraction number. …