Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Faculty Publications

Discipline
Institution
Keyword
Publication Year
File Type

Articles 3901 - 3930 of 4084

Full-Text Articles in Physical Sciences and Mathematics

Inequalities For Sums Of Independent Random Variables, N L. Carothers, S J. Dilworth Sep 1988

Inequalities For Sums Of Independent Random Variables, N L. Carothers, S J. Dilworth

Faculty Publications

A moment inequality is proved for sums of independent random variables in the Lorentz spaces LPtq, thus extending an inequality of Rosenthal. The latter result is used in combination with a square function inequality to give a proof of a Banach space isomorphism theorem. Further moment inequalities are also proved.

Go to article

Analysis Of The Convergence History Of Fluid Flow Through Nozzles With Shocks, Mohammad Saleem, A Cheer, M Hafez, T Pulliam Jul 1988

Analysis Of The Convergence History Of Fluid Flow Through Nozzles With Shocks, Mohammad Saleem, A Cheer, M Hafez, T Pulliam

Faculty Publications

"Convergence of iterative methods for the solution of the steady quasi-one-dimensional nozzle problem with shocks is considered. The finite-difference algorithms obtained from implicit schemes are used to approximate both the Euler and Navier-Stokes Equations. These algorithms are investigated for stability and convergence characteristics. The numerical methods are broken down into their matrix-vector components and then analyzed by examining a subset of the eigensystem using a method based on the Arnoldi process. The eigenvalues obtained by this method are accurate to within 5 digits for the largest ones and to within 2 digits for the ones smaller in magnitude compared the …

Go to article

Oxidative Degradation Of Glucose Adducts To Protein: Formation Of 3-(NE-Lysino)-Lactic Acid From Model Compounds And Glycated Proteins, Mahtab U. Ahmed, John A. Dunn, Michael D. Walla, Suzanne R. Thorpe, John W. Baynes Jun 1988

Oxidative Degradation Of Glucose Adducts To Protein: Formation Of 3-(NE-Lysino)-Lactic Acid From Model Compounds And Glycated Proteins, Mahtab U. Ahmed, John A. Dunn, Michael D. Walla, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

The chemistry of Maillard or browning reactions of glycated proteins is being studied in model systems in vitro in order to characterize potential reaction pathways and products in biological systems. In previous work with the Amadori rearrangement product N alpha-formyl-N epsilon-fructoselysine (fFL), an analog of glycated lysine residues in proteins, we showed that fFL was oxidatively cleaved between C-2 and C-3 of the carbohydrate chain to yield N epsilon-carboxymethyllysine (CML) and D-erythronic acid. We then detected CML in proteins glycated in vitro, as well as in human lens proteins and collagen in vivo (Ahmed, M. U., Thorpe, S. R., and …

Go to article

Experimental Study Of Nonlinear Conductance In Small Metallic Samples, Richard A. Webb, S. Washburn, C. P. Umbach May 1988

Experimental Study Of Nonlinear Conductance In Small Metallic Samples, Richard A. Webb, S. Washburn, C. P. Umbach

Faculty Publications

We have directly observed current-dependent, nonlinear contributions to the conductance fluctuations of phase-coherent metallic wires and loops. The fluctuations in the current-voltage curves are reproducible, asymmetric about I=0, and in qualitative agreement with theoretical predictions. In ac measurements, the nonlinear terms also generate large harmonic signals of the conductance fluctuations whose dependence on the drive current can be understood qualitatively. The spectra of harmonics from loops and wires have different dependences on the voltage across the sample.

Go to article

A Cytochemical Study Of The Transcriptional And Translational Regulation Of Nuclear Transition Protein 1 (Tp1), A Major Chromosomal Protein Of Mammalian Spermatids, Mohammad A. Heidaran, Richard M. Showman, Wilson Stephen Kistler May 1988

A Cytochemical Study Of The Transcriptional And Translational Regulation Of Nuclear Transition Protein 1 (Tp1), A Major Chromosomal Protein Of Mammalian Spermatids, Mohammad A. Heidaran, Richard M. Showman, Wilson Stephen Kistler

Faculty Publications

Immunocytochemical localization and in situ hybridization techniques were used to investigate the presence of spermatid nuclear transition protein 1 (TP1) and its mRNA during the various stages of spermatogenesis in the rat. A specific antiserum to TP1 was raised in a rabbit and used to show that TP1 is immunologically crossreactive among many mammals including humans. During spermatogenesis the protein appears in spermatids as they progress from step 12 to step 13, a period in which nuclear condensation is underway. The protein is lost during step 15. An asymmetric RNA probe generated from a TP1 cDNA clone identified TP1 mRNA …

Go to article

Experiments With Disposable Hypodermic Syringes, Glen T. Clayton, Thomas O. Callaway, Harry D. Downing Jan 1988

Experiments With Disposable Hypodermic Syringes, Glen T. Clayton, Thomas O. Callaway, Harry D. Downing

Faculty Publications

No abstract provided.

Go to article

Nonlocal Symmetries And Backlund Transformations For The Self-Dual Yang-Mills System, C. J. Papachristou, Kent B. Harrison Jan 1988

Nonlocal Symmetries And Backlund Transformations For The Self-Dual Yang-Mills System, C. J. Papachristou, Kent B. Harrison

Faculty Publications

The observation is made that generalized evolutionary isovectors of the self-dual Yang–Mills equation, obtained by "verticalization'' of the geometrical isovectors derived in a previous paper [J. Math. Phys. 28, 1261 (1987)], generate Bäcklund transformations for the self-dual system. In particular, new Bäcklund transformations are obtained by "verticalizing'' the generators of point transformations on the solution manifold. A geometric ansatz for the derivation of such (generally nonlocal) symmetries is proposed.

Go to article

Quasilinear Evolution Equations In Nonclassical Diffusion, Kenneth Kuttler, Elias Aifantis Jan 1988

Quasilinear Evolution Equations In Nonclassical Diffusion, Kenneth Kuttler, Elias Aifantis

Faculty Publications

After describing the motivation leading to some nonclassical diffusion equations, we formulate a general abstract nonlinear evolution equation and establish existence of solutions. Then we return to the original equation and discuss particular initial-boundary value problems.

Go to article

Hydrothermal Fluids And Petroleum In Surface Sediments Of Guaymas Basin, Gulf Of California: A Case Study, J. M. Gieskes, B. R. Simoneit, T. Brown, Timothy J. Shaw, Y. C. Wang, A. Magenheim Jan 1988

Hydrothermal Fluids And Petroleum In Surface Sediments Of Guaymas Basin, Gulf Of California: A Case Study, J. M. Gieskes, B. R. Simoneit, T. Brown, Timothy J. Shaw, Y. C. Wang, A. Magenheim

Faculty Publications

No abstract provided.

Go to article

Digital Neural Networks, Tony R. Martinez Jan 1988

Digital Neural Networks, Tony R. Martinez

Faculty Publications

Demands for applications requiring massive parallelism in symbolic environments have given rebirth to research in models labeled as neural networks. These models are made up of many simple nodes which are highly interconnected such that computation takes place as data flows amongst the nodes of the network. To present, most models have proposed nodes based on simple analog functions, where inputs are multiplied by weights and summed, the total then optionally being transformed by an arbitrary function at the node. Learning in these systems is accomplished by adjusting the weights on the input lines. This paper discusses the use of …

Go to article

Comparison Of Effective Medium Procedures For Optical Modeling Of Laminar Structures, David D. Allred, Robert F. Edgerton Jan 1988

Comparison Of Effective Medium Procedures For Optical Modeling Of Laminar Structures, David D. Allred, Robert F. Edgerton

Faculty Publications

This study addresses the question, "How can the optical properties of matter in ultrathin amorphous nonmetallic films in multilayers best be determined from reflectance (R) and transmission (T) measurements?" A blue shift in the band gap of plasma CVD a-Si:H/a-SiNx:H multilayers was reported several years ago. It was suggested that the shift in the band gap, Eg, Relative to bulk a-Si:H as given by the Tauç plot was due to quantum confinement effects. The purpose of this study is to evaluate the usefulness of various effective media theories (EMT) for determining the optical constants of materials in a multilayer and …

Go to article

Involutions On Banach Spaces And Reflexivity, S J. Dilworth Jan 1988

Involutions On Banach Spaces And Reflexivity, S J. Dilworth

Faculty Publications

No abstract provided.

Go to article

Interpolation Of Besov-Spaces, Ronald A. Devore, Vasil A. Popova Jan 1988

Interpolation Of Besov-Spaces, Ronald A. Devore, Vasil A. Popova

Faculty Publications

We investigate Besov spaces and their connection with dyadic spline approximation in Lp(Omega), 0 < p (less than or equal to) infinity. Our main results are: the determination of the interpolation spaces between a pair of Besov spaces; an atomic decomposition for functions in a Besov space; the characterization of the class of functions which have certain prescribed degree of approximation by dyadic splines.

Go to article

The Twentieth Fermat Number Is Composite, Jeff Young, Duncan A. Buell Jan 1988

The Twentieth Fermat Number Is Composite, Jeff Young, Duncan A. Buell

Faculty Publications

The twentieth Fermat number, F20 = 22^20 +1, has been proven composite by machine computation.

Go to article

Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele Jan 1988

Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele

Faculty Publications

Using a formulation of quantum electrodynamics that is not second quantized, but rather based on self-fields, we compute the anomalous magnetic moment of the electron to first order in the fine structure constant α. In the nonrelativistic (NR) case and in the dipole approximation, our result is ae≡(g—2)/2=(4Λ/3m)(α/2π), where Λ is a positive photon energy cutoff and m the electron mass. A reasonable choice of cutoff, Λ/m=¾, yields the correct sign and magnitude for g—2 namely, ae=+α/2π. . In our formulation the sign of a3 is correctly positive, …

Go to article

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.

Go to article

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.

Go to article

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.

Go to article

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.

Go to article

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.

Go to article

Can Programmers Reuse Software?, Scott N. Woodfield, David W. Embley, Del T. Scott Jul 1987

Can Programmers Reuse Software?, Scott N. Woodfield, David W. Embley, Del T. Scott

Faculty Publications

An experiment asked programmers untrained in reuse to evaluate component reusability. They did poorly. Are reusability's promises hollow? Or are there some answers?

Go to article

Surface Conductance Of A Copper Wire In A Fluid At High Pressure, Daniel L. Decker Jul 1987

Surface Conductance Of A Copper Wire In A Fluid At High Pressure, Daniel L. Decker

Faculty Publications

The three-dimensional flow of heat in a wire carrying a current and immersed in a liquid is solved in detail. Using this exact result the surface conductance of copper in petroleum ether has been measured as a function of pressure to 40 kbars. The measured surface conductance for copper in a fluid is very small, justifying approximations which yield results that are in agreement with a simplified one-dimensional heat-flow problem. Surprisingly, even at 40 kbars pressure a very large fraction of the joule heating within a wire with a length-to-diameter ratio of ~100 is dissipated through the ends of the …

Go to article

Superconductivity At 155 K, David D. Allred, S. R. Ovshinsky, R. T. Young, G. Demaggio, G. A. Van Der Leeden Jun 1987

Superconductivity At 155 K, David D. Allred, S. R. Ovshinsky, R. T. Young, G. Demaggio, G. A. Van Der Leeden

Faculty Publications

Transition to a superconducting zero-resistance state at 155 K is observed for the first time in bulk material. A new five-element compound has been synthesized with nominal composition Y1Ba2Cu3F2Oy. Fluorine plays a critical role in achieving this effect. X-ray diffraction and electron microprobe analysis indicate that the samples are multiphasic. Evidence is presented that the samples contain superconducting phases with onset temperatures considerably above 155 K. Magnetic measurements suggest a flux-trapping effect below 260 K, and diamagnetic deviations from Curie-Weiss behavior in the range from 250 K≤T≤100 K indicate that Meissner effect in a small superconducting volume fraction.

Go to article

Aurealcaulis Crossii Gen. Et Sp. Nov., An Arborescent, Osmundaceous Trunk From The Fort Union Formation (Paleocene), Wyoming, William D. Tidwell, Lee R. Parker Jun 1987

Aurealcaulis Crossii Gen. Et Sp. Nov., An Arborescent, Osmundaceous Trunk From The Fort Union Formation (Paleocene), Wyoming, William D. Tidwell, Lee R. Parker

Faculty Publications

Aurealcaulis crossii gen. et sp. nov., is based on permineralized trunks of an osmundaceous tree fern from the Paleocene Fort Union Formation from near Bitter Creek Station of southwestern Wyoming. This new species is characterized by centripetal (exarch) development of its xylem strands which form part of the leaf traces. Most of the leaf traces depart the stele as two segments that fuse into a single C-shaped petiole vascular strand outside of the outer cortex. Stipular expansions of the petiole bases of this species lack sclerenchyma, and roots arise from the lateral edges of leaf traces in the inner cortex. …

Go to article

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.

Go to article

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.

Go to article

Some Aspects Of The Isogroup Of The Self-Dual Yang-Mills System, C. J. Papachristou, B. Kent Harrison Jun 1987

Some Aspects Of The Isogroup Of The Self-Dual Yang-Mills System, C. J. Papachristou, B. Kent Harrison

Faculty Publications

A generalized isovector formalism is used to derive the isovectors and isogroup of the self-dual Yang-Mills (SDYM) equation in the so-called J formulation. In particular, the infinitesimal "hidden symmetry'' transformation, a linear system, and a well-known Backlund transformation of the SDYM equation are derived in the process. Thus symmetry and integrability aspects of the SDYM system appear in natural relationship to each other within the framework of the isovector approach.

Go to article

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 …

Go to article

The Sharpness Of Some Cluster Set Results, D. Rung, Samih Obaid Jan 1987

The Sharpness Of Some Cluster Set Results, D. Rung, Samih Obaid

Faculty Publications

We show that a recent cluster set theorem of Rung is sharp in a certain sense. This is accomplished through the construction of an interpolating sequence whose limit set is closed, totally disconnected and porous. The results also generalize some of Dolzenko's cluster set theorems.

Go to article

Anneal Induced Changes In Amorphous Semiconductor Multilayers, David D. Allred, Jesus González-Hernández, O. V. Nguyen Jan 1987

Anneal Induced Changes In Amorphous Semiconductor Multilayers, David D. Allred, Jesus González-Hernández, O. V. Nguyen

Faculty Publications

We have prepared, heat treated and characterized various amorphous semiconductor periodic multilayers and ultrathin films. These were prepared by several vapor deposition techniques at substrate temperatures ranging from 25°C to 300°C and possessed periodicities from 22 to 400Å. Films were subjected to isochronal thermal treatments at progressively higher temperatures. Two effects were observed: enhanced diffusion and retarded crystallization. Interdiffusion, at rates which are many orders of magnitude higher than those anticipated from crystalline data, was observed in a-Si/a-Ge multilayers. Crystallization of germanium, the more readily crystallized member of the couple, is retarded; the extent depends on the thickness of the …

Go to article

First Prev Next Last