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University of South Carolina

2004

Articles 1 - 30 of 30

Full-Text Articles in Physical Sciences and Mathematics

Sm2Nairo6, A Monoclinically Distorted Double Perovskite, Samuel J. Mugavero Iii, Irina V. Puzdrjakova, Mark D. Smith, Hans-Conrad Zur Loye Dec 2004

Sm2Nairo6, A Monoclinically Distorted Double Perovskite, Samuel J. Mugavero Iii, Irina V. Puzdrjakova, Mark D. Smith, Hans-Conrad Zur Loye

Faculty Publications

Single crystals of the lanthanide-containing iridate, disamarium sodium iridium hexaoxide, Sm2NaIrO6, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/n and is a double perovskite, consisting of a 1:1 ordered rock-salt-type lattice of corner-shared NaO6 and IrO6 distorted octahedra. Samarium occupies the eightfold coordination site generated by the connectivity of the octahedra.

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Analysis Of Process Controls In Land Surface Hydrological Cycle Over The Continental United States, Tajdarul Hassan Syed, Venkataraman Lakshmi, Evan Paleologos, Dag Lohmann, Kenneth Mitchell, James S. Famiglietti Nov 2004

Analysis Of Process Controls In Land Surface Hydrological Cycle Over The Continental United States, Tajdarul Hassan Syed, Venkataraman Lakshmi, Evan Paleologos, Dag Lohmann, Kenneth Mitchell, James S. Famiglietti

Faculty Publications

The paper uses two years (1997–1999) of data from the North American Land Data Assimilation System at National Centers for Environmental Prediction to analyze the variability of physical variables contributing to the hydrological cycle over the conterminous United States. The five hydrological variables considered in this study are precipitation, top layer soil moisture (0–10 cm), total soil moisture (0–200 cm), runoff, and potential evaporation. There are two specific analyses carried out in this paper. In the first case the principal components of the hydrological cycle are examined with respect to the loadings of the individual variables. This helps to ascertain …

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Outerplanar Crossing Numbers, The Circular Arrangement Problem And Isoperimetric Functions, Eva Czabarka, Ondrej Sykora, Laszlo A. Szekely, Imrich Vrt'o Nov 2004

Outerplanar Crossing Numbers, The Circular Arrangement Problem And Isoperimetric Functions, Eva Czabarka, Ondrej Sykora, Laszlo A. Szekely, Imrich Vrt'o

Faculty Publications

We extend the lower bound in [15] for the outerplanar crossing number (in other terminologies also called convex, circular and one-page book crossing number) to a more general setting. In this setting we can show a better lower bound for the outerplanar crossing number of hypercubes than the best lower bound for the planar crossing number. We exhibit further sequences of graphs, whose outerplanar crossing number exceeds by a factor of log n the planar crossing number of the graph. We study the circular arrangement problem, as a lower bound for the linear arrangement problem, in a general fashion. We …

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Modified Quantum Trajectory Dynamics Using A Mixed Wave Function Representation, Sophya Garashchuk, Vitaly A. Rassolov Nov 2004

Modified Quantum Trajectory Dynamics Using A Mixed Wave Function Representation, Sophya Garashchuk, Vitaly A. Rassolov

Faculty Publications

Dynamics of quantum trajectories provides an efficient framework for description of various quantum effects in large systems, but it is unstable near the wave function density nodes where the quantum potential becomes singular. A mixed coordinate space/polar representation of the wave function is used to circumvent this problem. The resulting modified trajectory dynamics associated with the polar representation is nonsingular and smooth. The interference structure and the nodes of the wave function density are described, in principle, exactly in the coordinate representation. The approximate version of this approach is consistent with the semiclassical linearized quantum force method [S. Garashchuk and …

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Resonance-Enhanced Multiphoton Ionization For Real-Time Monitoring Of Trichloroethylene Formed By Degradation Of Tetrachloroethylene Using Zero-Valent Zinc, Kui Chen, Jack E. Pender, John L. Ferry, S. Michael Angel Nov 2004

Resonance-Enhanced Multiphoton Ionization For Real-Time Monitoring Of Trichloroethylene Formed By Degradation Of Tetrachloroethylene Using Zero-Valent Zinc, Kui Chen, Jack E. Pender, John L. Ferry, S. Michael Angel

Faculty Publications

Resonance-enhanced multiphoton ionization (REMPI) is investigated as a potential technique for real-time monitoring of selected volatile organochloride compounds (VOCs). In a proof-of-concept experiment, the progress of the reductive-degradation of tetrachloroethylene (PCE) to trichloroethylene (TCE) by zero-valent zinc was monitored by REMPI measurements performed in the headspace above the PCE solution. Two-photon resonant REMPI spectra of TCE and PCE were recorded over the wavelength range 305–320 nm. The concentrations of PCE and TCE in the headspace were monitored by measurement of the ionization signal with 315.64- and 310.48-nm excitation for PCE and TCE, respectively. Calibration curves yielded a linear range of …

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Mohanty And Webb Reply, P. Mohanty, Richard A. Webb Oct 2004

Mohanty And Webb Reply, P. Mohanty, Richard A. Webb

Faculty Publications

A Reply to the Comment by V. I. Fal'ko et al.

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Polarization Of Nuclear Spins From The Conductance Of Quantum Wires, James A. Nesteroff, Yuriy V. Pershin Dr, Vladimir Privman Sep 2004

Polarization Of Nuclear Spins From The Conductance Of Quantum Wires, James A. Nesteroff, Yuriy V. Pershin Dr, Vladimir Privman

Faculty Publications

We devise an approach to measure the polarization of nuclear spins via conductance measurements. Specifically, we study the combined effect of external magnetic field, nuclear spin polarization, and Rashba spin-orbit interaction on the conductance of a quantum wire. Nonequilibrium nuclear spin polarization affects the electron energy spectrum making it time dependent. Changes in the extremal points of the spectrum result in time dependence of the conductance. The conductance oscillation pattern can be used to obtain information about the amplitude of the nuclear spin polarization and extract the characteristic time scales of the nuclear spin subsystem.

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Every Polynomial-Time 1-Degree Collapses If And Only If P=Pspace, Stephen A. Fenner, Stuart A. Kurtz, James S. Royer Sep 2004

Every Polynomial-Time 1-Degree Collapses If And Only If P=Pspace, Stephen A. Fenner, Stuart A. Kurtz, James S. Royer

Faculty Publications

No abstract provided.

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Every Polynomial-Time 1-Degree Collapses If And Only If P=Pspace, Stephen A. Fenner, Stuart A. Kurtz, James S. Royer Sep 2004

Every Polynomial-Time 1-Degree Collapses If And Only If P=Pspace, Stephen A. Fenner, Stuart A. Kurtz, James S. Royer

Faculty Publications

No abstract provided.

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A Physiochemically Constrained Seawater Culturing System For Production Of Benthic Foraminifera, Christopher J. Hintz, G. Thomas Chandler, Jay M. Bernhardt, Daniel C. Mccorkle, Suzanne M. Havach, Jessica K. Blanks, Timothy J. Shaw Jun 2004

A Physiochemically Constrained Seawater Culturing System For Production Of Benthic Foraminifera, Christopher J. Hintz, G. Thomas Chandler, Jay M. Bernhardt, Daniel C. Mccorkle, Suzanne M. Havach, Jessica K. Blanks, Timothy J. Shaw

Faculty Publications

No abstract provided.

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Geminal Model Chemistry Ii. Perturbative Corrections, Vitaly A. Rassolov, Feng Xu, Sophya Garashchuk Jun 2004

Geminal Model Chemistry Ii. Perturbative Corrections, Vitaly A. Rassolov, Feng Xu, Sophya Garashchuk

Faculty Publications

We introduce and investigate a chemical model based on perturbative corrections to the product of singlet-type strongly orthogonal geminals wave function. Two specific points are addressed (i) Overall chemical accuracy of such a model with perturbative corrections at a leading order; (ii) Quality of strong orthogonality approximation of geminals in diverse chemical systems. We use the Epstein–Nesbet form of perturbation theory and show that its known shortcomings disappear when it is used with the reference Hamiltonian based on strongly orthogonal geminals. Application of this model to various chemical systems reveals that strongly orthogonal geminals are well suited for chemical models, …

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Geomorphic Analysis Of Tidal Creek Networks, Karyn Inez Novakowski, Raymond Torres, L Robert Gardner, George Voulgaris May 2004

Geomorphic Analysis Of Tidal Creek Networks, Karyn Inez Novakowski, Raymond Torres, L Robert Gardner, George Voulgaris

Faculty Publications

The purpose of this study is to determine if concepts in terrestrial channel network analysis provide insight on intertidal creek network development and to present new metrics for their analysis. We delineated creek network geometry using high-resolution digital images of intertidal marsh near Georgetown, South Carolina. Analyses reveal that intertidal creek networks may be topologically random. Length-area relationships suggest that salt marsh and terrestrial networks have similar scaling properties, although the marsh networks are more elongate than terrestrial networks. To account for recurrent water exchange between creek basins at high tide, we propose that the landscape unit of geomorphic analyses …

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Growth And Transport Properties Of Complementary Germanium Nanowire Field Effect Transistors, Andrew B. Greytak, Lincoln J. Lauhon, Mark S. Gudiksen, Charles M. Lieber May 2004

Growth And Transport Properties Of Complementary Germanium Nanowire Field Effect Transistors, Andrew B. Greytak, Lincoln J. Lauhon, Mark S. Gudiksen, Charles M. Lieber

Faculty Publications

n- and p-type Ge nanowires were synthesized by a multistep process in which axial elongation, via vapor–liquid–solid (VLS) growth, and doping were accomplished in separate chemical vapor deposition steps. Intrinsic, single-crystal, Ge nanowires prepared by Au nanocluster-mediated VLS growth were surface-doped in situ using diborane or phosphine, and then radial growth of an epitaxial Ge shell was used to cap the dopant layer. Field-effect transistors prepared from these Ge nanowires exhibited on currents and transconductances up to 850 µA/µm and 4.9 µA/V, respectively, with device yields of >85%.

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Bohmian Dynamics On Subspaces Using Linearized Quantum Force, Vitaly A. Rassolov, Sophya Garashchuk Apr 2004

Bohmian Dynamics On Subspaces Using Linearized Quantum Force, Vitaly A. Rassolov, Sophya Garashchuk

Faculty Publications

In the de Broglie–Bohm formulation of quantum mechanics the time-dependent Schrödinger equation is solved in terms of quantum trajectories evolving under the influence of quantum and classical potentials. For a practical implementation that scales favorably with system size and is accurate for semiclassical systems, we use approximate quantum potentials. Recently, we have shown that optimization of the nonclassical component of the momentum operator in terms of fitting functions leads to the energy-conserving approximate quantum potential. In particular, linear fitting functions give the exact time evolution of a Gaussian wave packet in a locally quadratic potential and can describe the dominant …

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New Enhanced Tunneling In Nuclear Processes, Boris Ivlev, Vladimir Gudkov Mar 2004

New Enhanced Tunneling In Nuclear Processes, Boris Ivlev, Vladimir Gudkov

Faculty Publications

The small sub-barrier tunneling probability of nuclear processes can be dramatically enhanced by collision with incident charged particles. Semiclassical methods of theory of complex trajectories have been applied to nuclear tunneling, and conditions for the effects have been obtained. We demonstrate the enhancement of αparticle decay by incident proton with energy of about 0.25 MeV. We show that the general features of this process are common for other sub-barrier nuclear processes and can be applied to nuclear fission.

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Effect Of Spin-Orbit Interaction And In-Plane Magnetic Field On The Conductance Of A Quasi-One-Dimensional System, Yuriy V. Pershin Dr, James A. Nesteroff, Vladimir Privman Mar 2004

Effect Of Spin-Orbit Interaction And In-Plane Magnetic Field On The Conductance Of A Quasi-One-Dimensional System, Yuriy V. Pershin Dr, James A. Nesteroff, Vladimir Privman

Faculty Publications

We study the effect of spin-orbit interaction and in-plane effective magnetic field on the conductance of a quasi-one-dimensional ballistic electron system. The effective magnetic field includes the externally applied field, as well as the field due to polarized nuclear spins. The interplay of the spin-orbit interaction with effective magnetic field significantly modifies the band structure, producing additional subband extrema and energy gaps, introducing the dependence of the subband energies on the field direction. We generalize the Landauer formula at finite temperatures to incorporate these special features of the dispersion relation. The obtained formula describes the conductance of a ballistic conductor …

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Electronic Structure Of Nuclear-Spin-Polarization-Induced Quantum Dots, Yuriy V. Pershin Dr Feb 2004

Electronic Structure Of Nuclear-Spin-Polarization-Induced Quantum Dots, Yuriy V. Pershin Dr

Faculty Publications

We study a system in which electrons in a two-dimensional electron gas are confined by a nonhomogeneous nuclear-spin polarization. The system consists of a heterostructure that has nonzero nuclei spins. We show that in this system electrons can be confined into a dot region through a local nuclear-spin polarization. The nuclear-spin-polarization-induced quantum dot has interesting properties indicating that electron energy levels are time dependent because of the nuclear-spin relaxation and diffusion processes. Electron confining potential is a solution of diffusion equation with relaxation. Experimental investigations of the time dependence of electron energy levels will result in more information about nuclear-spin …

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Slow Spin Relaxation In Two-Dimensional Electron Systems With Antidots, Yuriy V. Pershin Dr, Vladimir Privman Feb 2004

Slow Spin Relaxation In Two-Dimensional Electron Systems With Antidots, Yuriy V. Pershin Dr, Vladimir Privman

Faculty Publications

We report a Monte Carlo investigation of the effect of a lattice of antidots on spin relaxation in twodimensional electron systems. The spin relaxation time is calculated as a function of geometrical parameters describing the antidot lattice, namely the antidot radius and the distance between their centers. It is shown that spin polarization relaxation can be efficiently suppressed by the chaotic spatial motion due to the antidot lattice. This phenomenon offers a new approach to spin coherence manipulation in spintronics devices.

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Energy Conserving Approximations To The Quantum Potential: Dynamics With Linearized Quantum Force, Sophya Garashchuk, Vitaly A. Rassolov Jan 2004

Energy Conserving Approximations To The Quantum Potential: Dynamics With Linearized Quantum Force, Sophya Garashchuk, Vitaly A. Rassolov

Faculty Publications

Solution of the Schrödinger equation within the de Broglie–Bohm formulation is based on propagation of trajectories in the presence of a nonlocal quantum potential. We present a new strategy for defining approximate quantum potentials within a restricted trial function by performing the optimal fit to the log-derivatives of the wave function density. This procedure results in the energy-conserving dynamics for a closed system. For one particular form of the trial function leading to the linear quantum force, the optimization problem is solved analytically in terms of the first and second moments of the weighted trajectory distribution. This approach gives exact …

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Using Microenvironmental Effects To Increase Loading And Stereoselectivity For Polymer Bound Nabh4 Reagents., James R. Blanton Jan 2004

Using Microenvironmental Effects To Increase Loading And Stereoselectivity For Polymer Bound Nabh4 Reagents., James R. Blanton

Journal of the South Carolina Academy of Science

No abstract provided.

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President's Message, David J. Stroup Jan 2004

President's Message, David J. Stroup

Journal of the South Carolina Academy of Science

No abstract provided.

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Building New Culture Media For Assisted Reproductive Technology., Mary N. Egbuniwe, H. Lee Higdon Iii, William R. Boone Jan 2004

Building New Culture Media For Assisted Reproductive Technology., Mary N. Egbuniwe, H. Lee Higdon Iii, William R. Boone

Journal of the South Carolina Academy of Science

No abstract provided.

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Bioinformatics: An Undergraduate Research/Teaching Tool., Abhishek Agrawal, Valgene L. Dunham Jan 2004

Bioinformatics: An Undergraduate Research/Teaching Tool., Abhishek Agrawal, Valgene L. Dunham

Journal of the South Carolina Academy of Science

No abstract provided.

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Characterization Of Microbial Communities In Tce-Contaminated Seep Zone Sediments., Brian A. Nevius, Christopher E. Bagwell, Robin L. Brigmon Jan 2004

Characterization Of Microbial Communities In Tce-Contaminated Seep Zone Sediments., Brian A. Nevius, Christopher E. Bagwell, Robin L. Brigmon

Journal of the South Carolina Academy of Science

No abstract provided.

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Table Of Contents Jan 2004

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.

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A Programming Environment For Static And Dynamic Distributed Systems., Seyed H. Roosta Jan 2004

A Programming Environment For Static And Dynamic Distributed Systems., Seyed H. Roosta

Journal of the South Carolina Academy of Science

No abstract provided.

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Scas Officers And Council Members 2004 - 2005 Jan 2004

Scas Officers And Council Members 2004 - 2005

Journal of the South Carolina Academy of Science

No abstract provided.

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Effects Of Low Tide Rainfall On Intertidal Zone Material Cycling, Raymond Torres, Miguel A. Goni, George Voulgaris, Charles R. Lovell, James T. Morris Jan 2004

Effects Of Low Tide Rainfall On Intertidal Zone Material Cycling, Raymond Torres, Miguel A. Goni, George Voulgaris, Charles R. Lovell, James T. Morris

Faculty Publications

Sediment transport by rainfall-runoff processes is well documented for terrestrial landscapes but few studies have focused on rainfall-runoff effects in intertidal areas. Here we present geochemical analyses performed on sediment samples collected during low tide irrigation experiments, and tidal channel turbidity measurements taken during natural rainfall over North Inlet Marsh, South Carolina. Order of magnitude approximations indicate that a single 10 minute storm may entrain 8-15% of the local annual average sediment accumulation. This rainfall-entrained material is enriched in organic nitrogen and marine algal matter, and therefore of high nutritional quality.

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Bohmian Dynamics On Subspaces Using Linearized Quantum Force, V. A. Rassolov, Sophya V. Garashchuk Jan 2004

Bohmian Dynamics On Subspaces Using Linearized Quantum Force, V. A. Rassolov, Sophya V. Garashchuk

Faculty Publications

In the de Broglie–Bohm formulation of quantum mechanics the time-dependent Schrödinger equation is solved in terms of quantum trajectories evolving under the influence of quantum and classical potentials. For a practical implementation that scales favorably with system size and is accurate for semiclassical systems, we use approximate quantum potentials. Recently, we have shown that optimization of the nonclassical component of the momentum operator in terms of fitting functions leads to the energy-conserving approximate quantum potential. In particular, linear fitting functions give the exact time evolution of a Gaussian wave packet in a locally quadratic potential and can describe the dominant …

Go to article

Geminal Model Chemistry Ii. Perturbative Corrections, V. A. Rassolov, F. Xu, Sophya V. Garashchuk Jan 2004

Geminal Model Chemistry Ii. Perturbative Corrections, V. A. Rassolov, F. Xu, Sophya V. Garashchuk

Faculty Publications

We introduce and investigate a chemical model based on perturbative corrections to the product of singlet-type strongly orthogonal geminals wave function. Two specific points are addressed (i) Overall chemical accuracy of such a model with perturbative corrections at a leading order; (ii) Quality of strong orthogonality approximation of geminals in diverse chemical systems. We use the Epstein–Nesbet form of perturbation theory and show that its known shortcomings disappear when it is used with the reference Hamiltonian based on strongly orthogonal geminals. Application of this model to various chemical systems reveals that strongly orthogonal geminals are well suited for chemical models, …

Go to article