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Faculty Publications

1987

University of South Carolina

Articles 1 - 12 of 12

Full-Text Articles in Physical Sciences and Mathematics

Normal-Metal Aharonov-Bohm Effect In The Presence Of A Transverse Electric Field, S. Washburn, H. Schmid, D. Kern, Richard A. Webb Oct 1987

Normal-Metal Aharonov-Bohm Effect In The Presence Of A Transverse Electric Field, S. Washburn, H. Schmid, D. Kern, Richard A. Webb

Faculty Publications

The effects of transverse electric fields on the conductance fluctuations in an Sb loop have been studied. We show that the electric field can be used to tune the position (or phase) of Aharonov-Bohm oscillations as well as to alter the aperiodic conductance fluctuation patterns. We disucss two mechanisms which might cause the observed dependence of the fluctuation pattern on transverse electric field. The first is the electrostatic Aharonov-Bohm effect, and the second is the spatial shifting of the electron trajectories by the electric field.

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Integer Squares With Constant Second Difference, Duncan A. Buell Oct 1987

Integer Squares With Constant Second Difference, Duncan A. Buell

Faculty Publications

The problem addressed is this: Do there exist nonconsecutive integers n0, n1, n2, . . ., such that the second differences of the squares of the ni are constant? Specifically, can that constant be equal to 2? A complete characterization of sequences of length four can be given. The question of whether or not sequences of length five exist is still open but the existence or nonexistence of such sequences can be described in a more algorithmic way than the simple statement of the problem.

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Observation Of An Oxygen Isotope Effect In Yba2Cu3O7, Kevin J. Leary, Hans Conrad Zur Loye, Steven W. Keller, Tanya A. Faltens, William K. Ham, James N. Michaels, Angelica M. Stacy Sep 1987

Observation Of An Oxygen Isotope Effect In Yba2Cu3O7, Kevin J. Leary, Hans Conrad Zur Loye, Steven W. Keller, Tanya A. Faltens, William K. Ham, James N. Michaels, Angelica M. Stacy

Faculty Publications

A small decrease in Tc of 0.3 K to 0.5 K is observed when as much as 90% of the 16O in YBa2Cu3O7 is substituted with18O. This result is consistent with our observation that there is an oxygen isotope effect in La1.85Sr0.15CuO4, but in contrast with previous reports that there is no isotope effect for YBa2Cu3O7. This new result suggests that phonons play an important role in the electron-pairing mechanism in YBa2Cu3O7.

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Sequentially Compact, Franklin-Rajagopalan Spaces, Peter J. Nyikos, J. E. Vaughan Sep 1987

Sequentially Compact, Franklin-Rajagopalan Spaces, Peter J. Nyikos, J. E. Vaughan

Faculty Publications

No abstract provided.

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Observation Of An Isotope Shift In The Superconducting Transition Temperature Of La1.85Sr0.15Cuo4, Tanya A. Faltens, William K. Ham, Steven W. Keller, Kevin J. Leary, James N. Michaels, Angelica M. Stacy, Hans Conrad Zur Loye, Donald E. Morris, T W. Barbee Iii, Marvin L. Cohen, Cohen S. Hoen, A Zettl Aug 1987

Observation Of An Isotope Shift In The Superconducting Transition Temperature Of La1.85Sr0.15Cuo4, Tanya A. Faltens, William K. Ham, Steven W. Keller, Kevin J. Leary, James N. Michaels, Angelica M. Stacy, Hans Conrad Zur Loye, Donald E. Morris, T W. Barbee Iii, Marvin L. Cohen, Cohen S. Hoen, A Zettl

Faculty Publications

An oxygen isotope shift is observed in superconducting La1.85Sr0.15CuO4 when 18O is substituted partially for 16O; the superconducting transition temperature Tc is lowered by 0.3 to 1.0 K in different samples. We examine these results using conventioanl phonon-mediated BCS theory and conclude that, for La1.85Sr0.15CuO4, phonons play an important role in the pairing mechanism.

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Search For Isotope Effect In Superconducting Y-Ba-Cu-O, L C. Bourne, M F. Crommie, A Zettl, Hans Conrad Zur Loye, S W. Keller, K L. Leary, Angelica M. Stacy, K J. Chang, Marvin L. Cohen, Donald E. Morris Jun 1987

Search For Isotope Effect In Superconducting Y-Ba-Cu-O, L C. Bourne, M F. Crommie, A Zettl, Hans Conrad Zur Loye, S W. Keller, K L. Leary, Angelica M. Stacy, K J. Chang, Marvin L. Cohen, Donald E. Morris

Faculty Publications

An isotope effect has been searched for in the high-Tc, superconductor YBa2Cu307 —b through substitution of 180 for 16O. No shift in the superconducting transition temperature T, is observed by electrical resistivity or magnetic susceptibility measurements. We discuss the implications of this result for mechanisms of superconductivity in the high-T, oxides.

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Length-Independent Voltage Fluctuations In Small Devices, A. Benoit, C. P. Umbach, R. B. Laibowitz, Richard A. Webb Jun 1987

Length-Independent Voltage Fluctuations In Small Devices, A. Benoit, C. P. Umbach, R. B. Laibowitz, Richard A. Webb

Faculty Publications

Conductance fluctuations in one-dimensional lines of length L shorter than the phase-coherence length Lφ are not universal but diverge as L-2. Using the Onsager relations and voltage additivity, we show that the voltage fluctuations are independent of the distance between voltage probes. The antisymmetric (Hall-type) contribution to the voltage fluctuations is constant for all values of L. Measurements of the voltage fluctuations and correlation function between different regions in Au and Sb lines confirm these results.

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Effect Of Phosphate On The Kinetics And Specificity Of Glycation Of Protein, Nancy G. Watkins, Carolyn I. Neglia-Fisher, Daniel G. Dyer, Suzanne R. Thorpe, John W. Baynes May 1987

Effect Of Phosphate On The Kinetics And Specificity Of Glycation Of Protein, Nancy G. Watkins, Carolyn I. Neglia-Fisher, Daniel G. Dyer, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

The glycation (nonenzymatic glycosylation) of several proteins was studied in various buffiner os rder to assess the effects of buffering ions on the kinetics and specificity of glycation of protein. Incubation of RNase with glucose in phosphate buffer resulted in inactivation of the enzyme because of preferential modification of lysine residues ino r near the activsei te. In contrast, in the cationic buffers, 3-(N-morpholino)propanesulfonic acid and 3-(N-tris(hydroxymethyl)rnethylamino)- 2-hydroxypropanesulfonica cid, the kineticso f glycation of RNase were decreased 2- to 3-fold, there was a decrease in glycation of active site versus peripheral lysines, and the enzyme was resistant to inactivation by …

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A 3-D Gravity Tectonic Study Of Ita Mai Tai Guyot: An Uncompensated Seamount In The East Mariana Basin, Bruce S. Wedgeworth, James N. Kellogg Jan 1987

A 3-D Gravity Tectonic Study Of Ita Mai Tai Guyot: An Uncompensated Seamount In The East Mariana Basin, Bruce S. Wedgeworth, James N. Kellogg

Faculty Publications

Ita Mai Tai is a large, locally uncompensated seamount on the eastern edge of the East Mariana Basin. A large positive gravity anomaly of 254 mgal characterizes the summit and a low of -69 mgal, the surrounding moat. Using polygonal prisms to approximate the bathymetry, the observed gravity was inverted to calculate an average density of 2.59 g/ems for the seamount. Observed-calculated gravity residuals are reduced by including the flanking sedimentary basins and a dense volcanic conduit. The drill sites from DSDP Legs 20 and 89 describe a volcanic edifice formed in the Aptian!Albian on Jmassic/Cretaceous crust. The volcanism is …

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Isostatic Compensation And Conduit Structures Of Western Pacific Seamounts: Results Of Three-Dimensional Gravity Modeling, James N. Kellogg, Bruce S. Wedgeworth, Jeffrey T. Freymueller Jan 1987

Isostatic Compensation And Conduit Structures Of Western Pacific Seamounts: Results Of Three-Dimensional Gravity Modeling, James N. Kellogg, Bruce S. Wedgeworth, Jeffrey T. Freymueller

Faculty Publications

Detailed three-dimensional polygonal prism models of two large western Pacific seamounts show that the 135 mgal difference in the observed sea surface gravity over the two can be best explained by similar mean densities (2.6 gjcm3) and crustal thickening under one seamount (Airy isostatic compensation). Observed calculated residuals are further reduced by including dense (2.9 gjcm3) vertical feeder pipes or volcanic conduits in the models. Dense conduits or fracture zones 5 to 17 km in diameter are located under many, if not all, craters on volcanic islands and seamounts. Results from the detailed seamount studies can be generalized using exact …

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Large Deviations For Processes With Independent Increments, James Lynch, Jayaram Sethuraman Jan 1987

Large Deviations For Processes With Independent Increments, James Lynch, Jayaram Sethuraman

Faculty Publications

Let X be a topological space and F denote the Borel σ-field in X. A family of probability measures {Pλ} is said to obey the large deviation principle (LDP) with rate function I(⋅) if Pλ(A) can be suitably approximated by exp{−λinfx∈AI(x)} for appropriate sets A in F. Here the LDP is studied for probability measures induced by stochastic processes with stationary and independent increments which have no Gaussian component. It is assumed that the moment generating function of the increments exists and thus the sample paths of such stochastic processes lie in the space of functions of bounded variation. The …

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Class Groups Of Quadratic Fields Ii, Duncan A. Buell Jan 1987

Class Groups Of Quadratic Fields Ii, Duncan A. Buell

Faculty Publications

A computation has been made of the noncyclic class groups of imaginary quadratic fields Q(√-D) for even and odd discriminants - D from 0 to - 25000000. Among the results are that 95% of the class groups are cyclic, and that -11203620 and -18397407 are the first discriminants of imaginary quadratic fields for which the class group has rank three in the 5-Sylow subgroup. The latter was known to be of rank three; this computation demonstrates that it is the first odd discriminant of 5-rank three or more.

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