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The Correlation Between Carbon-Proton and Proton-Proton Coupling Constants

Description: The correlation between the carbon-proton and proton-proton coupling constants have been studied in various 13 systems. Isocrotonic acid-carboxyl-3C, crotonic acid- 13 13 carboxyl-3C, and 5-norbornene-2-carboxylic acid-carboxyl-3C- 1,5,6,7,7-hexachloro were synthesized and their carbonproton coupling constants were analyzed. Nmr studies showed the magnitudes of the carbon-proton coupling constants to correlate well with analogous protonproton coupling constants, although the values of the couplings were larger than expected. The geminal olefinic couplings were considerably larger than all other couplings, but they were self-consistent. The signs of the carbon-proton coupling constants also were in agreement without exception with the signs of analogous proton-proton coupling constants.
Date: December 1975
Creator: Seiwell, Ruth R.
Partner: UNT Libraries

THE COUPLING IMPEDANCE OF A TOROIDAL BEAM TUBE WITH CIRCULAR CROSS SECTION.

Description: IN THIS PAPER, THE LONGITUDINAL COUPLING IMPEDANCE OF A TOROIDAL BEAM TUBE WITH CIRCULAR CROSS SECION IS DERIVED IN THE FREQUENCY DOMAIN USING THE TOROIDAL COORDINATE SYSTEM. EXACT, ALTHOUGH COUPLED, DIFFERENTIAL EQUATIONS FOR THE AZIMUTHAL FIELD COMPONENTS ARE OBTAINED. AN APPROXIAMTE SOLUTION, VALID IN THE LIMIT OF SMALL CURVATURE, IS THEN DERIVED. ASSUMING EXTREME RELATIVISTIC ENERGIES AND A BEAM TUBE WITH PERFECTLY CONDUCTING WALLS, ONE FINDS A CLOSED-FORM EXPRESSION FOR THE PURELY REACTIVE COUPLING IMPEDANCE WHICH AT LOW MODE NUMBERS IS DEPENDENT ON THE TUBE GEOMETRY BUT WHICH AT VERY LARGE MODE NUMBERS APPROACHES THE FREE SPACE IMPEDANCE.
Date: March 29, 1999
Creator: HAHN,H.
Partner: UNT Libraries Government Documents Department

Field Theory On the World Sheet: Mean Field Expansion And Cutoff Dependence

Description: Continuing earlier work, we apply the mean field method to the world sheet representation of a simple field theory. In particular, we study the higher order terms in the mean field expansion, and show that their cutoff dependence can be absorbed into a running coupling constant. The coupling constant runs towards zero in the infrared, and the model tends towards a free string. One cannot fully reach this limit because of infrared problems, however, one can still apply the mean field method to the high energy limit (high mass states) of the string.
Date: January 10, 2007
Creator: Bardakci, Korkut
Partner: UNT Libraries Government Documents Department

Multiple Valley Couplings in Nanometer Si MOSFETs

Description: We investigate the couplings between different energy band valleys in a MOSFET device using self-consistent calculations of million-atom Schroedinger-Poisson Equations. Atomistic empirical pseudopotentials are used to describe the device Hamiltonian and the underlying bulk band structure. The MOSFET device is under nonequilibrium condition with a source-drain bias up to 2V, and a gate potential close to the threshold potential. We find that all the intervalley couplings are small, with the coupling constants less than 3 meV. As a result, the system eigenstates derived from different bulk valleys can be calculated separately. This will significantly reduce the simulation time, because the diagonalization of the Hamiltonian matrix scales as the third power of the total number of basis functions.
Date: July 11, 2008
Creator: Wang, Lin-Wang; Deng, Hui-Xiong; Jiang, Xiang-Wei; Luo, Jun-Wei; Li, Shu-Shen; Xia, Jian-Bai et al.
Partner: UNT Libraries Government Documents Department

Carrier hopping in disordered semiconducting polymers: How accurate is the Miller-Abrahams model?

Description: We performed direct calculations of carrier hopping rates in strongly disordered conjugated polymers based on the atomic structure of the system, the corresponding electronic states and their coupling to all phonon modes. We found that the dependence of hopping rates on distance and the dependence of the mobility on temperature are significantly different than the ones stemming from the simple Miller-Abrahams model, regardless of the choice of the parameters in the model. A model that satisfactorily describes the hopping rates in the system and avoids the explicit calculation of electron-phonon coupling constants was then proposed and verified. Our results indicate that, in addition to electronic density of states, the phonon density of states and the spatial overlap of the wavefunctions are the quantities necessary to properly describe carrier hopping in disordered conjugated polymers.
Date: July 30, 2010
Creator: Vukmirovic, Nenad & Wang, Lin-Wang
Partner: UNT Libraries Government Documents Department

Fiscal Year 1998 report theoretical studies of ground energy coupling

Description: A method for calculating the redistribution of resonance radiation in hot, dense plasmas is developed by extending the Frequency Fluctuation Model (FFM). This paper is devoted to a brief review of lineshape theory in the linear response approximation, and an introduction to the FFM approach to the modeling of lineshapes in plasmas. This discussion begins with a consideration of the spectral lines emitted by complex ions in plasmas. As is well known, the lineshape is determined by the time- dependent coupling of the ion with the plasma environment. This plasma-emitter interaction, leads to Stark broadening of the spectral lines, and traditionally has been considered in the approximation which treats the ef&@ of the electrons on the emitting ion in the impact limit while the ionic perturbation is� taken to be quasi-static. In this approximation, the time dependence of the perturbation has been eliminated, resulting in a spectral line shape that has purely homogeneous and inhomogeneous contributions and that is described by a simple sum of independent electron imp� act broadened static components. In order to clarify the concepts presented, examples of radiative redistribution functions for simple cases are presented. Included is an example of an X-ray laser pumped system which illustrates the capability of the mpdel to provide a sensitive method for the study of radiative transfer under plasma conditions of partial redistribution. That is, in cases where the strong mixing limit is not attained so that the mixing of the inhomogeneous spectral line components is not fast enough to produce a completely redistributed line.
Date: December 10, 1998
Creator: Klein, L.
Partner: UNT Libraries Government Documents Department

Scalar and tensor couplings in kaon decays

Description: In the past few years charged kaon experiments have indicated possible scalar and tensor couplings in semileptonic kaon decays (K{yields}{pi}e{nu}). These couplings, if correct, are not predicted by the Standard Model and may indicate the onset of new physics. We present a summary of the existing data and a new, precision measurement of these couplings in the neutral kaon system based on a 3% subset of the data taken by the KTeV (E799) experiment at Fermilab.
Date: May 10, 1999
Creator: Tesarek, Richard J.
Partner: UNT Libraries Government Documents Department

Boson pair production and triple gauge couplings

Description: The D0 and CDF Collaborations measure boson pair production including W{gamma}, WW, WZ, ZZ and Z{gamma} production in p{anti p} collisions at {radical}s = 1800 GeV. New results, from direct measurements, are described including W{gamma}, WW, and Z{gamma} production cross sections and limits on non-Standard Model triple gauge boson couplings. The limits on anomalous WW{gamma}, WWZ, Z{gamma}{gamma} and ZZ{gamma} couplings are the most restrictive available. Prospects for Run II are discussed.
Date: June 1, 1997
Creator: Diehl, H.T. & Collaborations, D0 and CDF
Partner: UNT Libraries Government Documents Department

Waveguide Coupling via Magnetic Gratings with Effective Strips

Description: This article provides an overview of an approach convenient for describing intermediate gratings for two types of applications: both metafilms and the coupling of incident waves to waveguide modes or diffraction orders.
Date: February 20, 2018
Creator: Roccapriore, Kevin M.; Lyvers, David P.; Brown, Dean P.; Poutrina, Ekaterina; Urbas, Augustine M.; Germer, Thomas A. et al.
Partner: UNT College of Arts and Sciences

A brief analog investigation of inertia coupling in rolling maneuvers of an airplane configuration using a variable-incidence wing as the longitudinal control

Description: From Summary: "An analog computer study was made in order to investigate the inertia coupling in rolling maneuvers of an airplane configuration utilizing a variable-incidence wing for longitudinal control. A five-degree-of-freedom system of equations was used, and only one set of flight conditions was included in this study. The results, when compared to those for a conventional tail-control airplane, indicated significant advantages for the variable-incidence-wing type of control in reducing undesired dynamic effects during rolling maneuvers."
Date: August 6, 1957
Creator: Gillis, Clarence L.
Partner: UNT Libraries Government Documents Department

Atomic electron correlations in intense laser fields

Description: Abstract. This talk examines two distinct cases in strong opbical fields where electron correlation plays an important role in the dynamic.s. In the first. example, strong coupling in a two-electron-like system is manifested as an intensity-dependent splitting in the ionized electron energy distribution. This two-electron phenomenon (dubbed continuum-continuum Autler-Townes effect) is analogous to a strongly coupled two- level, one-electron atom but raises some intriguing questions regarding the exact nature of electron-electron correlation. The second case examines the evidence for two-electron ionization in the strong-field tunneling limit. Although our ability to describe the one- electron dynamics has obtained a quantitative level of understanding, a description of the two (multiple) electron ionization remains unc
Date: September 3, 1998
Creator: Agostini, P. A.; DiMauro, L. F.; Kulander, K.; Sheehy, B. & Walker, B.
Partner: UNT Libraries Government Documents Department

Alternative approach to general coupled linear optics

Description: The Twiss parameters provide a convenient description of beam optics in uncoupled linear beamlines. For coupled beamlines, a variety of approaches are possible for describing the linear optics; here, we propose an approach and notation that naturally generalizes the familiar Twiss parameters to the coupled case in three degrees of freedom. Our approach is based on an eigensystem analysis of the matrix of second-order beam moments, or alternatively (in the case of a storage ring) on an eigensystem analysis of the linear single-turn map. The lattice functions that emerge from this approach have an interpretation that is conceptually very simple: in particular, the lattice functions directly relate the beam distribution in phase space to the invariant emittances. To emphasize the physical significance of the coupled lattice functions, we develop the theory from first principles, using only the assumption of linear symplectic transport. We also give some examples of the application of this approach, demonstrating its advantages of conceptual and notational simplicity.
Date: November 29, 2005
Creator: Wolski, Andrzej
Partner: UNT Libraries Government Documents Department

Enhanced Electron-Phonon Coupling at Metal Surfaces

Description: The Born-Oppenheimer approximation (BOA) decouples electronic from nuclear motion, providing a focal point for most quantum mechanics textbooks. However, a multitude of important chemical, physical and biological phenomena are driven by violations of this approximation. Vibronic interactions are a necessary ingredient in any process that makes or breaks a covalent bond, for example, conventional catalysis or enzymatically delivered biological reactions. Metastable phenomena associated with defects and dopants in semiconductors, oxides, and glasses entail violation of the BOA. Charge exchange in inorganic polymers, organic slats and biological systems involves charge- induced distortions of the local structure. A classic example is conventional superconductivity, which is driven by the electron-lattice interaction. High-resolution angle-resolved photoemission experiments are yielding new insight into the microscopic origin of electron-phonon coupling (EPC) in anisotropic two-dimensional systems. Our recent surface phonon measurement on the surface of a high-Tc material clearly indicates an important momentum dependent EPC in these materials. In the last few years we have shifted our research focus from solely looking at electron phonon coupling to examining the structure/functionality relationship at the surface of complex transition metal compounds. The investigation on electron phonon coupling has allowed us to move to systems where there is coupling between the lattice, the electrons and the spin.
Date: August 4, 2010
Creator: Plummer, Ward E.
Partner: UNT Libraries Government Documents Department

A simple way to characterize linear coupling in a storage ring

Description: The techniques of normal form analysis, well known in the literature, can be used to provide a straightforward characterization of linear betatron dynamics in a coupled lattice. Here, we consider both the beam distribution and the betatron oscillations in a storage ring, assuming that the beam emittances and betatron actions respectively are provided as parameters. We find that the beta functions for uncoupled motion generalize in a simple way to the coupled case. Defined in the way that we propose, the beta functions remain well behaved (positive and finite) under all circumstances, and have essentially the same physical significance for the beam size and betatron oscillations as in the uncoupled case. We discuss a technique for making direct measurements of the ratio of the coupled lattice functions at different points in the lattice.
Date: March 24, 2004
Creator: Wolski, Andrzej
Partner: UNT Libraries Government Documents Department

Analysis of coupling impedance bench measurements using Bethe's diffraction theory

Description: In this paper we study the validity of coupling impedance bench measurements, comparing two of the most commonly used formulas to the result obtained, applying a modified version of Bethe's theory of diffraction to a lumped impedance in a coaxial beam pipe. The equations found provide a quantitative expression for the influence of the wire thickness used in the measurement of the real and imaginary part of the longitudinal impedance. The precision achievable in an actual measurement is therefore discussed. The method presented can also be applied in the presence of distributed impedances as well as to the analysis of transverse impedance measurements.
Date: June 1, 2001
Creator: De Santis, Stefano
Partner: UNT Libraries Government Documents Department

Recirculation in multiple wave conversions

Description: A one-dimensional multiple wave-conversion model is constructed that allows energy recirculation in ray phase space. Using a modular eikonal approach, the connection coefficients for this model are calculated by ray phase-space methods. Analytical results (confirmed numerically) show that all connection coefficients exhibit interference effects that depend on an interference phase, calculated from the coupling constants and the area enclosed by the intersecting rays. This conceptual model, which focuses on the topology of intersecting rays in phase space, is used to investigate how mode conversion between primary and secondary waves is modified by the presence of a tertiary wave.
Date: July 30, 2008
Creator: Kaufman, A. N.; Brizard, A.J.; Kaufman, A.N. & Tracy, E.R.
Partner: UNT Libraries Government Documents Department