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2007

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Articles 4351 - 4380 of 6758

Full-Text Articles in Physical Sciences and Mathematics

Carbazolyl Nitrenium Ion:  Electron Configuration And Antiaromaticity Assessed By Laser Flash Photolysis, Trapping Rate Constants, Product Analysis, And Computational Studies, Arthur Winter, Harry H. Gibson, Daniel E. Falvey Jan 2007

Carbazolyl Nitrenium Ion:  Electron Configuration And Antiaromaticity Assessed By Laser Flash Photolysis, Trapping Rate Constants, Product Analysis, And Computational Studies, Arthur Winter, Harry H. Gibson, Daniel E. Falvey

Arthur Winter

Laser flash photolysis of 1-(carbazol-9-yl)-2,4,6-trimethylpyridinium tetrafluoroborate generates the carbazolyl nitrenium ion (τ = 333 ns, kobs = 3.0 × 106 M-1s-1) having absorption bands at 570 and 620 nm in CH3CN. The nitrenium ion is found to have reactivity comparable to structurally similar closed-shell diarylnitrenium ions, but spectroscopic evidence favors an open-shell singlet diradical assignment for the observed nitrenium ion. The carbazolyl nitrenium ion is also more reactive than diarylnitrenium ions as a likely result of antiaromatic character. Ab initio and hybrid DFT calculations were performed to address the degree of antiaromaticity in this and similar nitrenium ions through analysis …

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Benzylic Cations With Triplet Ground States:  Computational Studies Of Aryl Carbenium Ions, Silylenium Ions, Nitrenium Ions, And Oxenium Ions Substituted With Meta Π Donors, Arthur Winter, Daniel E. Falvey, Christopher J. Cramer, Benjamin F. Gherman Jan 2007

Benzylic Cations With Triplet Ground States:  Computational Studies Of Aryl Carbenium Ions, Silylenium Ions, Nitrenium Ions, And Oxenium Ions Substituted With Meta Π Donors, Arthur Winter, Daniel E. Falvey, Christopher J. Cramer, Benjamin F. Gherman

Arthur Winter

Density functional theory (B3LYP/6-31G(d,p)) was used to predict the effect of meta substitution on aryl cationic (Ar−X+) species, including aryloxenium ions, arylsilylenium ions, arylnitrenium ions, and arylcarbenium ions. Multireference second-order perturbation theory (CASPT2) calculations were used to benchmark the quantitative accuracy of the DFT calculations for representative systems. Substituting the meta positions on these species with π donors stabilizes a π,π* diradical state analogous to the well-known m-xylylene diradical. Notably, the 3,5-bis(N,N-dimethylamino)benzyl cation is predicted to have a triplet ground state by 1.9 kcal/mol by DFT and to have essentially degenerate singlet−triplet states at the CASPT2(10,9) level of theory. Adding …

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The Role Of Achiral Pyrazolidinone Templates In Enantioselective Diels−Alder Reactions:  Scope, Limitations, And Conformational Insights, Mukund P. Sibi, Levi M. Stanley, Xiaoping Nie, Lakshmanan Venkatraman, Mei Liu, Craig P. Jasperse Jan 2007

The Role Of Achiral Pyrazolidinone Templates In Enantioselective Diels−Alder Reactions:  Scope, Limitations, And Conformational Insights, Mukund P. Sibi, Levi M. Stanley, Xiaoping Nie, Lakshmanan Venkatraman, Mei Liu, Craig P. Jasperse

Levi M. Stanley

We have evaluated the role of achiral pyrazolidinone templates in conjunction with chiral Lewis acids in room temperature, enantioselective Diels−Alder cycloadditions. The role of the fluxional N(1) substituent was examined, with the bulky 1-naphthylmethyl group providing enantioselectivities up to 99% ee, while templates with smaller fluxional groups gave lower selectivities. High selectivities were also observed in reactions of 7d with chiral Lewis acids derived from relatively small chiral ligands, suggesting the pyrazolidinone templates are capable of relaying stereochemical information from the ligand to the reaction center. Lewis acids capable of adapting square planar geometries, such as Cu(OTf)2, Cu(ClO4)2, and Pd(ClO4)2, …

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A "Sound" Approach To Fourier Transforms: Using Music To Teach Trigonometry, Bruce Kessler Jan 2007

A "Sound" Approach To Fourier Transforms: Using Music To Teach Trigonometry, Bruce Kessler

Bruce Kessler

If a large number of educated people were asked, ``What was your most exciting class?'', odds are that very few of them would answer ``Trigonometry.'' The subject is generally presented in a less-than-exciting fashion, with the repeated caveat that ``you'll need this when you take calculus,'' or ``this has lots of applications'' without ever really seeing many of them. This manuscript addresses how the author is trying to change this tradition by exposing casual students from kindergarten to college to Joseph Fourier's secret, that nearly any function can be built out of sine and cosine curves. And music serves as …

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Room-Temperature Electron Spin Dynamics In Free-Standing Zno Quantum Dots, W. K. Liu, K. M. Whitaker, A. L. Smith, Kevin R. Kittilstved, B. H. Robinson, D. R. Gamelin Jan 2007

Room-Temperature Electron Spin Dynamics In Free-Standing Zno Quantum Dots, W. K. Liu, K. M. Whitaker, A. L. Smith, Kevin R. Kittilstved, B. H. Robinson, D. R. Gamelin

Kevin R. Kittilstved

Conduction band electrons in colloidal ZnO quantum dots have been prepared photochemically and examined by electron paramagnetic resonance spectroscopy. Nanocrystals of 4.6 nm diameter containing single S-shell conduction band electrons have g*=1.962 and a room-temperature ensemble spin-dephasing time of T2*=25  ns, as determined from linewidth analysis. Increasing the electron population leads to increased g* and decreased T2*, both associated with formation of P-shell configurations. A clear relationship between T2* and hyperfine coupling with 67Zn(I=5/2) is observed.

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Binding And Templation Of Nanoparticle Receptors To Peptide Alpha-Helices Through Surface Recognition, P. S. Ghosh, A. Verma, Vincent M. Rotello Jan 2007

Binding And Templation Of Nanoparticle Receptors To Peptide Alpha-Helices Through Surface Recognition, P. S. Ghosh, A. Verma, Vincent M. Rotello

Vincent Rotello

Nanoparticles featuring highly flexible chains provide templateable surfaces for recognition of peptides.

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Farming Systems Research On Crop Diversification, Tillage, And Management Effects On Yield, Pests, And Environmental Quality In A Semi-Arid Environment, Andrew W. Lenssen, U. Sainju, T. Caesar-Tonthat, B. Allen, R. Lartey Jan 2007

Farming Systems Research On Crop Diversification, Tillage, And Management Effects On Yield, Pests, And Environmental Quality In A Semi-Arid Environment, Andrew W. Lenssen, U. Sainju, T. Caesar-Tonthat, B. Allen, R. Lartey

Andrew W. Lenssen

Available water, depleted soil quality, and weed competition are important constraints to crop production in the northern Great Plains. The traditional rotation in the region has been spring wheat with summer fallow, which is used to accrue additional soil moisture for the subsequent wheat crop. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water and inorganic nitrogen, decreasing the efficiency of fallow and increasing soil erosion. Chemical fallow and zero tillage systems improve soil water status for subsequent crops (Lenssen et al., 2007a), allowing for increased cropping intensity and improved nutrient cycling (Lenssen et al., …

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Energy Pathways And Directionality In Deformation Twinning, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu Jan 2007

Energy Pathways And Directionality In Deformation Twinning, S. Kibey, J. B. Liu, Duane D. Johnson, H. Sehitoglu

Duane D. Johnson

We present ab initiodensity functional theory calculations of twinning energy pathways for two opposite twinning modes, (111)[112¯] and (111)[1¯1¯2], in fcc materials to examine the directional nature of twinning which cannot be explained by classical twin nucleationmodels or the “twinnability” criterion. By accounting for these energy pathways in a multiscale model, we quantitatively predict the critical twinning stress for the (111)[1¯1¯2] mode to be substantially higher compared to the favorable (111)[112¯] mode (whose predicted stresses are in agreement with experiment), thus, ruling out twinning in the (111)[1¯1¯2] mode.

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2-Aminopyrimidine-3,3,3-Triphenyl- Propanoic Acid (1/1), Mateusz F. Serafin, Kraig A. Wheeler Jan 2007

2-Aminopyrimidine-3,3,3-Triphenyl- Propanoic Acid (1/1), Mateusz F. Serafin, Kraig A. Wheeler

Kraig A. Wheeler

The title bimolecular compound, C4H5N3·C21H18O2, constructed from 2-aminopyrimidine and 3,3,3-triphenylpropanoic acid, forms a tetramolecular hydrogen-bonded motif via O—H...N, N—H...O and N—H...N contacts. This aggregate organizes to give crystal-packing motifs with hydrophilic and hydrophobic regions.

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Markov Chain Monte Carlo Defect Identification In Nde Images, Aleksandar Dogandžić, Benhong Zhang Jan 2007

Markov Chain Monte Carlo Defect Identification In Nde Images, Aleksandar Dogandžić, Benhong Zhang

Aleksandar Dogandžić

We derive a hierarchical Bayesian method for identifying elliptically‐shaped regions with elevated signal levels in NDE images. We adopt a simple elliptical parametric model for the shape of the defect region and assume that the defect signals within this region are random following a truncated Gaussian distribution. Our truncated‐Gaussian model ensures that the signals within the defect region are higher than the baseline level corresponding to the noise‐only case. We derive a closed‐form expression for the kernel of the posterior probability distribution of the location, shape, and defect‐signal distribution parameters (model parameters). This result is then used to develop Markov …

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Institutional Fragmentation And Normative Compromise In Global Environmental Governance: What Prospects For Re-Embedding?, Maria Ivanova Jan 2007

Institutional Fragmentation And Normative Compromise In Global Environmental Governance: What Prospects For Re-Embedding?, Maria Ivanova

Maria Ivanova

No abstract provided.

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Discovery Of A Molecular Outflow In The Haro 6-10 Star-Forming Region, Irena Stojimirovic, Gopal Narayanan, Ronald L. Snell Jan 2007

Discovery Of A Molecular Outflow In The Haro 6-10 Star-Forming Region, Irena Stojimirovic, Gopal Narayanan, Ronald L. Snell

Gopal Narayanan

No abstract provided.

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Goods-Herschel Measurements Of The Dust Attenuation Of Typical Star-Forming Galaxies At High Redshift: Observations Of Uv-Selected Galaxies At Z~2, N. Reddy, M. Dickinson, D. Elbaz, G. Morrison, Mauro Giavalisco, R. Ivison, C. Papovich, D. Scott, V. Buat, D. Burgarella, V. Charmandaris, E. Daddi, G. Magdis, E. Murphy, B. Altieri, H. Aussel, H. Dannerbauer, K. Dasyra, H. S. Hwang, J. Kartaltepe, R. Leiton, B. Magnelli, P. Popesso Jan 2007

Goods-Herschel Measurements Of The Dust Attenuation Of Typical Star-Forming Galaxies At High Redshift: Observations Of Uv-Selected Galaxies At Z~2, N. Reddy, M. Dickinson, D. Elbaz, G. Morrison, Mauro Giavalisco, R. Ivison, C. Papovich, D. Scott, V. Buat, D. Burgarella, V. Charmandaris, E. Daddi, G. Magdis, E. Murphy, B. Altieri, H. Aussel, H. Dannerbauer, K. Dasyra, H. S. Hwang, J. Kartaltepe, R. Leiton, B. Magnelli, P. Popesso

Mauro Giavalisco

We take advantage of the sensitivity and resolution of Herschel at 100 and 160 micron to directly image the thermal dust emission and investigate the infrared luminosities, L(IR), and dust obscuration of typical star-forming (L*) galaxies at high redshift. Our sample consists of 146 UV-selected galaxies with spectroscopic redshifts 1.51e10 Lsun at z~2 are luminous infrared galaxies (LIRGs) with a median L(IR)=(2.2+/-0.3)e11 Lsun. Typical galaxies at 1.5

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Luminous And High Stellar Mass Candidate Galaxies At Z\Approx8 Discovered In Candels, Haojing Yan, Steven L. Finkelstein, Kuang-Han Huang, Russell E. Ryan, Henry C. Ferguson, Anton M. Koekemoer, Norman A. Grogin, Mark Dickinson, Jeffrey A. Newman, Rachel S. Somerville, Romeel Davé, S. M. Faber, Casey Papovich, Yicheng Guo, Mauro Giavalisco, Kyoung-Soo Lee, Naveem Reddy, Asantha R. Cooray, Brian D. Siana, Nimish P. Hathi, Giovanni G. Fazio, Matthew Ashby, Benjamin J. Weiner, Ray A. Lucas, Avishai Dekel, Laura Pentericci, Christopher J. Conselice, Dale D. Kocevski, Kamson Lai Jan 2007

Luminous And High Stellar Mass Candidate Galaxies At Z\Approx8 Discovered In Candels, Haojing Yan, Steven L. Finkelstein, Kuang-Han Huang, Russell E. Ryan, Henry C. Ferguson, Anton M. Koekemoer, Norman A. Grogin, Mark Dickinson, Jeffrey A. Newman, Rachel S. Somerville, Romeel Davé, S. M. Faber, Casey Papovich, Yicheng Guo, Mauro Giavalisco, Kyoung-Soo Lee, Naveem Reddy, Asantha R. Cooray, Brian D. Siana, Nimish P. Hathi, Giovanni G. Fazio, Matthew Ashby, Benjamin J. Weiner, Ray A. Lucas, Avishai Dekel, Laura Pentericci, Christopher J. Conselice, Dale D. Kocevski, Kamson Lai

Mauro Giavalisco

One key goal of the {\it Hubble Space Telescope} Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey is to track galaxy evolution back to $z\approx 8$. Its two-tiered "wide and deep" strategy bridges significant gaps in existing near-infrared surveys. Here we report on $z\approx 8$ galaxy candidates selected as F105W-band dropouts in one of its deep fields, which covers $\sim 62.9$ arcmin$^2$ to 4 ks per filter depth in the Great Observatories Origins Deep Survey southern field. We construct two independent samples using different but legitimate photometry and procedure. While they differ significantly on an object-by-object basis, our conclusions based on …

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Variations Of Twentieth-Century Temperature And Precipitation Extreme Indicators In The Northeast United States, Michael L. Griffiths, Raymond S. Bradley Jan 2007

Variations Of Twentieth-Century Temperature And Precipitation Extreme Indicators In The Northeast United States, Michael L. Griffiths, Raymond S. Bradley

Raymond S Bradley

An examination of five temperature and five precipitation extreme indicators reveals an increase in both temperature and precipitation extremes over the 1926–2000 period in the northeast United States, with most of this increase occurring over the past four decades. Empirical orthogonal function (EOF) analysis of winter frost days (FD) and warm nights (TN90) and also winter consecutive dry days (CDD) and very wet days (R95T) over the 1950–2000 period reveals that some of the variability associated with changes in these extremes may be explained by variations in the Arctic Oscillation (AO), El Niño–Southern Oscillation (ENSO), and Pacific–North American (PNA) pattern. …

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Observation Of Dipole-Like Gap Solitons In Self-Defocusing Waveguide Lattices, Lq Tang, Cb Lou, Xs Wang, Dh Song, Xy Chen, Jj Xu, Zg Chen, H Susanto, K Law, Pg Kevrekidis Jan 2007

Observation Of Dipole-Like Gap Solitons In Self-Defocusing Waveguide Lattices, Lq Tang, Cb Lou, Xs Wang, Dh Song, Xy Chen, Jj Xu, Zg Chen, H Susanto, K Law, Pg Kevrekidis

Panos Kevrekidis

We observe dipole-like gap solitons in two-dimensional waveguide lattices optically induced with a self-defocusing nonlinearity. Under appropriate conditions, two mutually coherent input beams excited in neighboring lattice sites evolve into a self-trapped state, whose spatial power spectrum and stability depend strongly on the initial excitation conditions. Our experimental observations are compared with numerical simulations.

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Dynamic Critical Behavior Of The Chayes-Machta-Swendsen-Wang Algorithm, Youjin Deng, Timothy M. Garoni, Jonathan Machta, Giovanni Ossola, Marco Polin, Alan D. Sokal Jan 2007

Dynamic Critical Behavior Of The Chayes-Machta-Swendsen-Wang Algorithm, Youjin Deng, Timothy M. Garoni, Jonathan Machta, Giovanni Ossola, Marco Polin, Alan D. Sokal

Jonathan Machta

We study the dynamic critical behavior of the Chayes-Machta dynamics for the Fortuin-Kasteleyn random-cluster model, which generalizes the Swendsen-Wang dynamics for the q-state Potts model to noninteger q, in two and three spatial dimensions, by Monte Carlo simulation. We show that the Li-Sokal bound z≥α/ν is close to but probably not sharp in d=2 and is far from sharp in d=3, for all q. The conjecture z≥β/ν is false (for some values of q) in both d=2 and d=3.

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Membrane Fluctuations Around Inclusions, Christian Santangelo, Oded Farago Jan 2007

Membrane Fluctuations Around Inclusions, Christian Santangelo, Oded Farago

Christian Santangelo

The free energy of inserting a protein into a membrane is determined by considering the variation in the spectrum of thermal fluctuations in response to the presence of a rigid inclusion. Both numerically and through a simple analytical approximation, we find that the primary effect of fluctuations is to reduce the effective surface tension, hampering the insertion at low surface tension. Our results, which should also be relevant for membrane pores, suggest (in contrast to classical nucleation theory) that a finite surface tension is necessary to facilitate the opening of a pore.

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Do Killing-Yano Tensors Form A Lie Algebra?, David Kastor, Sourya Ray, Jenny Traschen Jan 2007

Do Killing-Yano Tensors Form A Lie Algebra?, David Kastor, Sourya Ray, Jenny Traschen

David Kastor

Killing-Yano tensors are natural generalizations of Killing vectors. We investigate whether Killing-Yano tensors form a graded Lie algebra with respect to the Schouten-Nijenhuis bracket. We find that this proposition does not hold in general, but that it does hold for constant curvature spacetimes. We also show that Minkowski and (anti)-deSitter spacetimes have the maximal number of Killing-Yano tensors of each rank and that the algebras of these tensors under the SN bracket are relatively simple extensions of the Poincare and (A)dS symmetry algebras.

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Geometric Theory Of Columnar Phases On Curved Substrates, Christian Santangelo, Vincenzo Vitelli, Randall D. Kamien, David R. Nelson Jan 2007

Geometric Theory Of Columnar Phases On Curved Substrates, Christian Santangelo, Vincenzo Vitelli, Randall D. Kamien, David R. Nelson

Christian Santangelo

We study thin self-assembled columns constrained to lie on a curved, rigid substrate. The curvature presents no local obstruction to equally spaced columns in contrast with curved crystals for which the crystalline bonds are frustrated. Instead, the vanishing compressional strain of the columns implies that their normals lie on geodesics which converge (diverge) in regions of positive (negative) Gaussian curvature, in analogy to the focusing of light rays by a lens. We show that the out of plane bending of the cylinders acts as an effective ordering field.

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On Certain Integral Schreier Graphs Of The Symmetric Group, Pe Gunnells, Ra Scott, Bl Walden Jan 2007

On Certain Integral Schreier Graphs Of The Symmetric Group, Pe Gunnells, Ra Scott, Bl Walden

Paul Gunnells

We compute the spectrum of the Schreier graph of the symmetric group Sn corresponding to the Young subgroup S2×Sn−2 and the generating set consisting of initial reversals. In particular, we show that this spectrum is integral and for n≥8 consists precisely of the integers {0,1,…,n}. A consequence is that the first positive eigenvalue of the Laplacian is always 1 for this family of graphs.

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Reaction- Limited Sintering In Nearly Saturated Environments, Benny Davidovitch, Deniz Ertas, Thomas C. Halsey Jan 2007

Reaction- Limited Sintering In Nearly Saturated Environments, Benny Davidovitch, Deniz Ertas, Thomas C. Halsey

Benny Davidovitch

We study the shape and growth rate of necks between sintered spheres with dissolutionprecipitation dynamics in the reaction-limited regime. We determine the critical shape that separates those initial neck shapes that can sinter from those that necessarily dissolve, as well as the asymptotic evolving shape of sinters far from the critical shape. We compare our results with past results for the asymptotic neck shape in closely related but more complicated models of surface dynamics; in particular we confirm a scaling conjecture, originally due to Kuczinsky. Finally, we consider the relevance of this problem to the diagenesis of sedimentary rocks and …

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Precision Measurements Of The Nucleon Strange Form Factors At Q2∼0.1  Gev^2, A. Acha, K. A. Aniol, D. S. Armstrong, J. Arrington, T. Averett, S. L. Bailey, J. Barber, A. Beck, H. Benaoum, J. Benesch, P. Y. Bertin, P. Bosted, F. Butaru, E. Burtin, G. D. Cates, Y. C. Chao, J. P. Chen, E. Chudakov, E. Cisbani, B. Craver, F. Cusanno, R. De Leo, P. Decowski, A. Deur, R. J. Feuerbach, J. M. Finn, S. Frullani, S. A. Fuchs, K. Fuoti, R. Gilman, L. E. Glesener, K. Grimm, J. M. Grames, J. O. Hansen, J. Hansknecht, D. W. Higinbotham, R. Holmes, T. Holmstrom, H. Ibrahim, C. W. De Jager, X. Jiang, J. Katich, L. J. Kaufman, A. Kelleher, P. M. King, A. Kolarkar, S. Kowalksi, E. Kuchina, Krishna Kumar, L. Lagamba, P. Laviolette, J. Lerose, R. A. Lindgren, D. Lhuillier, N. Liyanage, D. J. Margaziotis, P. Markowitz, D. G. Meekins, Z. E. Meziani, R. Michaels, B. Mofit, S. Nanda, V. Nelyubin, K. Otis, K. D. Paschke, S. K. Phillips, M. Poelker, R. Pomatsalyuk, M. Potokar, Y. Prok, A. Puckett, X. Qian, Y. Qiang, B. Reitz, J. Roche, A. Saha, B. Sawatzky, J. Singh, K. Slifer, S. Sirca, R. Snyder, P. Solvingnon, P. A. Souder, M. L. Stutzman, R. Subedi, R. Suleiman, V. Sulkosky, W. A. Tobias, P. E. Ulmer, G. M. Urciuoli, K. Wang, A. Whitbeck, R. Wilson, B. Wojsekhowsi, H. Yao, Y. Ye, X. Zhan, X. Zheng, S. Zhou, V. Ziskin Jan 2007

Precision Measurements Of The Nucleon Strange Form Factors At Q2∼0.1  Gev^2, A. Acha, K. A. Aniol, D. S. Armstrong, J. Arrington, T. Averett, S. L. Bailey, J. Barber, A. Beck, H. Benaoum, J. Benesch, P. Y. Bertin, P. Bosted, F. Butaru, E. Burtin, G. D. Cates, Y. C. Chao, J. P. Chen, E. Chudakov, E. Cisbani, B. Craver, F. Cusanno, R. De Leo, P. Decowski, A. Deur, R. J. Feuerbach, J. M. Finn, S. Frullani, S. A. Fuchs, K. Fuoti, R. Gilman, L. E. Glesener, K. Grimm, J. M. Grames, J. O. Hansen, J. Hansknecht, D. W. Higinbotham, R. Holmes, T. Holmstrom, H. Ibrahim, C. W. De Jager, X. Jiang, J. Katich, L. J. Kaufman, A. Kelleher, P. M. King, A. Kolarkar, S. Kowalksi, E. Kuchina, Krishna Kumar, L. Lagamba, P. Laviolette, J. Lerose, R. A. Lindgren, D. Lhuillier, N. Liyanage, D. J. Margaziotis, P. Markowitz, D. G. Meekins, Z. E. Meziani, R. Michaels, B. Mofit, S. Nanda, V. Nelyubin, K. Otis, K. D. Paschke, S. K. Phillips, M. Poelker, R. Pomatsalyuk, M. Potokar, Y. Prok, A. Puckett, X. Qian, Y. Qiang, B. Reitz, J. Roche, A. Saha, B. Sawatzky, J. Singh, K. Slifer, S. Sirca, R. Snyder, P. Solvingnon, P. A. Souder, M. L. Stutzman, R. Subedi, R. Suleiman, V. Sulkosky, W. A. Tobias, P. E. Ulmer, G. M. Urciuoli, K. Wang, A. Whitbeck, R. Wilson, B. Wojsekhowsi, H. Yao, Y. Ye, X. Zhan, X. Zheng, S. Zhou, V. Ziskin

Krishna Kumar

We report new measurements of the parity-violating asymmetry APV in elastic scattering of 3 GeV electrons off hydrogen and He4 targets with ⟨θlab⟩≈6.0°. The He4 result is APV=(+6.40±0.23(stat)±0.12(syst))×10−6. The hydrogen result is APV=(−1.58±0.12(stat)±0.04(syst))×10−6. These results significantly improve constraints on the electric and magnetic strange form factors GsE and GsM. We extract GsE=0.002±0.014±0.007 at ⟨Q2⟩=0.077  GeV2, and GsE+0.09GsM=0.007±0.011±0.006 at ⟨Q2⟩=0.109  GeV2, providing new limits on the role of strange quarks in the nucleon charge and magnetization distributions.

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Regionalization And Democratization Through International Law: Intertwined Jurisdictions, Scales And Politics In The Columbia River Treaty, Eve Vogel Jan 2007

Regionalization And Democratization Through International Law: Intertwined Jurisdictions, Scales And Politics In The Columbia River Treaty, Eve Vogel

Eve Vogel

No abstract provided.

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Closure Under Transfinite Extensions, Edgar E. Enochs, Alina Iacob, Overtoun Jenda Jan 2007

Closure Under Transfinite Extensions, Edgar E. Enochs, Alina Iacob, Overtoun Jenda

Alina Iacob

The closure under extensions of a class of objects in an abelian category is often an important property of that class. Recently the closure of such classes under transfinite extensions (both direct and inverse) has begun to play an important role in several areas of mathematics, for example in Quillen’s theory of model categories and in the theory of cotorsion pairs. In this paper we prove that several important classes are closed under transfinite extensions

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Closure Under Transfinite Extensions, Edgar E. Enochs, Alina Iacob, Overtoun Jenda Jan 2007

Closure Under Transfinite Extensions, Edgar E. Enochs, Alina Iacob, Overtoun Jenda

Alina Iacob

The closure under extensions of a class of objects in an abelian category is often an important property of that class. Recently the closure of such classes under transfinite extensions (both direct and inverse) has begun to play an important role in several areas of mathematics, for example, in Quillen's theory of model categories and in the theory of cotorsion pairs. In this paper we prove that several important classes are closed under transfinite extensions.

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Water Hammer Dissipation In Pneumatic Slug Tests, David Ostendorf, Don J. Degroot, Philip J. Dunaj Jan 2007

Water Hammer Dissipation In Pneumatic Slug Tests, David Ostendorf, Don J. Degroot, Philip J. Dunaj

David Ostendorf

We model and measure the dissipation of water hammer induced by well casing and water elasticity with rapid valve opening at the start of a pneumatic slug test. The higher-frequency water hammer can obscure slower, aquifer-controlled, underdamped oscillations of the rigid water column, so a quantitative description of the elastic motion improves the ability of a slug test to calibrate the aquifer permeability k. Internal friction attenuates the water hammer, subject to a known headspace pressure at the air/water interface and equilibrium pressure at the top of the well screen. An analytical elastic solution is presented and matched to an …

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Microbial Development In Distillers Wet Grains Produced During Fuel Ethanol Production From Corn (Zea Mays), R. Michael Lehman, Kurt A. Rosentrater Jan 2007

Microbial Development In Distillers Wet Grains Produced During Fuel Ethanol Production From Corn (Zea Mays), R. Michael Lehman, Kurt A. Rosentrater

Kurt A. Rosentrater

Distillers grains are coproduced with ethanol and carbon dioxide during the production of fuel ethanol from the dry milling and fermentation of corn grain, yet there is little basic microbiological information on these materials. We undertook a replicated field study of the microbiology of distillers wet grains (DWG) over a 9 day period following their production at an industrial fuel ethanol plant. Freshly produced DWG had a pH of about 4.4, a moisture content of about 53.5% (wet mass basis), and 4 x 10(5) total yeast cells/g dry mass, of which about 0.1% were viable. Total bacterial cells were initially …

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Spatial Symmetry Groups As Sensorimotor Guidelines, Gin Mccollum Jan 2007

Spatial Symmetry Groups As Sensorimotor Guidelines, Gin Mccollum

Gin McCollum

While some aspects of neuroanatomical organization are related to packing and access rather than to function, other aspects of anatomical/physiological organization are directly related to function. The mathematics of symmetry groups can be used to determine logical structure in projections and to relate it to function. This paper reviews two studies of the symmetry groups of vestibular projections that are related to the spatial functions of the vestibular complex, including gaze, posture, and movement. These logical structures have been determined by finding symmetry groups of two vestibular projections directly from physiological and anatomical data. Logical structures in vestibular projections are …

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Computing And Introductory Statistics, Daniel Kaplan Jan 2007

Computing And Introductory Statistics, Daniel Kaplan

Daniel T. Kaplan

Much of the computing that students do in introductory statistics courses is based on techniques that were developed before computing became inexpensive and ubiquitous. Now that computing is readily available to all students, instructors can change the way we teach statistical concepts. This article describes computational ideas that can support teaching George Cobb's Three Rs of statistical inference: Randomize, Repeat, Reject.

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