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

Physical Sciences and Mathematics Commons™

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

Selected Works

Discipline
Institution
Keyword
Publication Year
Publication
File Type

Articles 20581 - 20610 of 21971

Full-Text Articles in Physical Sciences and Mathematics

43. Karl Kratzl, Otto Vogl Mar 1997

43. Karl Kratzl, Otto Vogl

Otto Vogl

No abstract provided.

Go to article

Small Scale Electronic Transport In Diamond Microcrystals., M. Jaeger, S. Hyun, Anthony Day, M. Thorpe, B. Golding Feb 1997

Small Scale Electronic Transport In Diamond Microcrystals., M. Jaeger, S. Hyun, Anthony Day, M. Thorpe, B. Golding

Anthony Roy Day

The interpretation of electronic transport in polycrystalline diamond has proven difficult as a result of the disorder arising from physical and chemical inhomogeneities. We describe experimental methods, based on electron beam lithography, for studying transport in single crystallites grown by CVD on Si substrates. The electrical contacting process utilizes the flexibility of the scanning electron microscope to write metallic contacts to individual crystallites with lateral dimensions of a few μm. A detailed analysis of the current distribution in the crystals allows us to extract the electronic conductivity from arbitrarily shaped, faceted crystals.

Go to article

Stiffness Of Measurement System And Significant Figures Of Displacement Which Are Required To Interpret Adhesional Force Curves, Nancy Burnham, Kunio Takahashi, Hubert Pollock, Tadao Onzawa Feb 1997

Stiffness Of Measurement System And Significant Figures Of Displacement Which Are Required To Interpret Adhesional Force Curves, Nancy Burnham, Kunio Takahashi, Hubert Pollock, Tadao Onzawa

Nancy A. Burnham

Force curves obtained from an elastic contact theory are shown and compared with experimental results. In the elastic contact theory, a pin-on-disk contact is assumed and the following interaction are taken into consideration; (i) elastic deformation, (ii) the specific energy of adhesion in the area of the contact, which is expressed as the difference between the surface energies and the interface energy, (iii) the long-range interaction outside the area of contact, assuming the additivity of the Lennard-Jones type potential, and (iv) another elastic term for the measurement system such as the cantilever stiffness of an atomic force microscope (AFM). In …

Go to article

44. Vogl Receives Honorary Doctoral Degree From Osaka University, Koichi Hatada Feb 1997

44. Vogl Receives Honorary Doctoral Degree From Osaka University, Koichi Hatada

Otto Vogl

No abstract provided.

Go to article

Turing Universality Of Neural Nets (Revisited), J. Pedro Neto, Hava Siegelmann, J. Félix Costa, C. P. Suárez Araujo Jan 1997

Turing Universality Of Neural Nets (Revisited), J. Pedro Neto, Hava Siegelmann, J. Félix Costa, C. P. Suárez Araujo

Hava Siegelmann

We show how to use recursive function theory to prove Turing universality of finite analog recurrent neural nets, with a piecewise linear sigmoid function as activation function. We emphasize the modular construction of nets within nets, a relevant issue from the software engineering point of view.

Go to article

The Use Of The Johnson-Neyman Confidence Bands And Mutiple Regression Models To Investigate Interaction Effects: Important Tools For Educational Researchers And Program Evaluators, John Fraas, Isadore Newman Jan 1997

The Use Of The Johnson-Neyman Confidence Bands And Mutiple Regression Models To Investigate Interaction Effects: Important Tools For Educational Researchers And Program Evaluators, John Fraas, Isadore Newman

John W. Fraas

No abstract provided.

Go to article

Molecular Gas And Infrared Emission In Hcg 31 And Hcg 92 (Stephan's Quintet) And Tidal Interactions In Compact Group Environment, Min S. Yun, L Verdes-Montenegro, A Del Olmo, J Perea Jan 1997

Molecular Gas And Infrared Emission In Hcg 31 And Hcg 92 (Stephan's Quintet) And Tidal Interactions In Compact Group Environment, Min S. Yun, L Verdes-Montenegro, A Del Olmo, J Perea

Min S. Yun

We present the interferometric measurements of 2.6 mm CO (J 5 13 0) emission (uFWHM 1 50) and the analysis of IRAS HIRES images of two Hickson compact groups HCG 31 and HCG 92 (“Stephan’s Quintet”). The far-infrared (FIR) emission is concentrated to a single region in HCG 31 while it is clearly extended and peaks near the group center in HCG 92. CO emission is weak in HCG 31, and the brightest peak occurs in the overlap region between the galaxies A and C. CO emission is detected only in galaxy C (NGC 7319) in HCG 92, and the …

Go to article

The Voltammetry Of Sc3@C82, Mark Anderson, Harry Dorn, Paul Burbank, Steven Stevenson, James Gibson Jan 1997

The Voltammetry Of Sc3@C82, Mark Anderson, Harry Dorn, Paul Burbank, Steven Stevenson, James Gibson

Mark R. Anderson

Many endohedral metallofullerenes have a C82 cage surrounding the metals, even though the normal arc-vaporization method of fullerene preparation does not generate C82 in significant abundance.1-10Manolopous et al.11-13attribute the low abundance of empty-cage C82 to the unfavorable electron configuration of this species. Consequently, the prevalence of C82 in metallofullerenes may be the result of an electron transfer from the encapsulated metal atoms to the fullerene cage.10-13 The extent of this charge transfer also contributes to the properties (e.g. catalytic, superconductive, nonlinear optical, and ferromagnetic) that are attributed to the endohedral metallofullerenes.14,15Because of the importance of the charge transfer reaction, characterization …

Go to article

Low Pressure Synthesis Of Bulk, Polycrystalline Gallium Nitride, Alberto Argoitia, Cliff C. Hayman, John C. Angus, Long Wang, Jeffrey S. Dyck, Kathleen Kash Jan 1997

Low Pressure Synthesis Of Bulk, Polycrystalline Gallium Nitride, Alberto Argoitia, Cliff C. Hayman, John C. Angus, Long Wang, Jeffrey S. Dyck, Kathleen Kash

Jeffrey Dyck

Thick films of polycrystalline GaN were grown at low pressures by direct reaction of atomic nitrogen with liquid Ga without the presence of a substrate. The crystals were confirmed to be wurtzitic GaN by x-ray diffraction, transmission electron microscopy, Raman spectroscopy, and elemental analysis. Photoluminescence spectra showed near band edge peaks and broad yellow band emission at both 298 and 10 K. The results show that atomic nitrogen is an attractive alternative to high pressure N2 for the saturation of liquid gallium with nitrogen for the synthesis of bulk GaN.

Go to article

A Feedback Control Structure For On-Line Learning Tasks, Manfred Huber, Roderic Grupen Jan 1997

A Feedback Control Structure For On-Line Learning Tasks, Manfred Huber, Roderic Grupen

Roderic Grupen

This paper addresses adaptive control architectures for systems that respond autonomously to changing tasks. Such systems often have many sensory and motor alternatives and behavior drawn from these produces varying quality solutions. The objective is then to ground behavior in control laws which, combined with resources, enumerate closed-loop behavioral alternatives. Use of such controllers leads to analyzable and predictable composite system, permitting the construction of abstract behavioral models. Here, discrete event system and reinforcement learning techniques are employed to constrain the behavioral alternatives and to synthesize behavior on-line. To illustrate this, a quadruped

Go to article

Learning To Coordinate Controllers -- Reinforcement Learning On A Control Basis, Manfred Huber, Roderic Grupen Jan 1997

Learning To Coordinate Controllers -- Reinforcement Learning On A Control Basis, Manfred Huber, Roderic Grupen

Roderic Grupen

Autonomous robot systems operating in an uncertain environment have to be reactive and adaptive in order to cope with changing environment conditions and task requirements. To achieve this, the hybrid control architecture presented in this paper uses reinforcement learning on top of a Discrete Event Dynamic System (DEDS) framework to learn to supervise a set of basis controllers in order to achieve a given task. The use of an abstract system model in the automatically derived supervisor reduces the complexity of the learning problem. In addition, safety constraints may be imposed a priori, such that the system learns on-line in …

Go to article

Numerical Solution Of The Eigenvalue Problem For Hermitian Toeplitz Matrices, William Trench, Michael Ng Jan 1997

Numerical Solution Of The Eigenvalue Problem For Hermitian Toeplitz Matrices, William Trench, Michael Ng

William F. Trench

No abstract provided.

Go to article

Nmr And Vortex Lattice Melting In Yba2cu3o7, Charles Recchia, J Martindale, C Pennington, W Hults, J Smith Jan 1997

Nmr And Vortex Lattice Melting In Yba2cu3o7, Charles Recchia, J Martindale, C Pennington, W Hults, J Smith

Charles H Recchia

No abstract provided.

Go to article

The Brain As A Symbol-Processing Machine., Armando F. Rocha Jan 1997

The Brain As A Symbol-Processing Machine., Armando F. Rocha

Armando F Rocha

The knowledge accumulated about the biochemistry of the synapsis in the last decades completely changes the notion of brain processing founded exclusively over an electrical mechanism, toward that supported by a complex chemical message exchange occurring both locally, at the synaptic site, as well as at other localities, depending on the solubility of the involved chemical substances in the extracellular compartment. These biochemical transactions support a rich symbolic processing of the information both encoded by the genes and provided by actual data collected from the surrounding environment, by means of either special molecular or cellular receptor systems. In this processing, …

Go to article

An Augmented Galerkin Method For Singular Integral Equations With Hilbert Kernel, S. Abbasbandy, E. Babolian Jan 1997

An Augmented Galerkin Method For Singular Integral Equations With Hilbert Kernel, S. Abbasbandy, E. Babolian

Saeid Abbasbandy

In recent papers, Delves [2] and others [1], [3] described a Chebyshev series method for the numerical solution of integral equations with non-singular kernels or some particular singular kernels, for example Green's function kernel, logarithmic and Cauchy kernels and so on. In this paper we describe a Fourier series expansion method for a class of singular integral equations with Hilbert kernel and constant coefficients. We give a number of numerical examples showing that Galerkin method works well in practice.

Go to article

Local Nonequilibrium Transport Models, Sergey Sobolev Jan 1997

Local Nonequilibrium Transport Models, Sergey Sobolev

Sergey Sobolev

No abstract provided.

Go to article

Local Non-Equilibrium Diffusion Effects On The Kinetic Phase Boundaries In Solidification, Sergey Sobolev Jan 1997

Local Non-Equilibrium Diffusion Effects On The Kinetic Phase Boundaries In Solidification, Sergey Sobolev

Sergey Sobolev

No abstract provided.

Go to article

Pseudo-Steady States In The Model Of The Bray-Liebhafsky Oscillatory Reaction, Zeljko D. Cupic Jan 1997

Pseudo-Steady States In The Model Of The Bray-Liebhafsky Oscillatory Reaction, Zeljko D. Cupic

Zeljko D Cupic

No abstract provided.

Go to article

The Time Evolution Of Unstable Monopoles, Moataz Emam Jan 1997

The Time Evolution Of Unstable Monopoles, Moataz Emam

Moataz Emam

No abstract provided.

Go to article

Neuroendocrine Aspects Of Primary Endogenous Depression Xv. Mathematical Modeling Of Nocturnal Melatonin Secretion In Major Depressives And Normal Controls, L. Kathleen Sekula, Joseph F. Lucke, E. Kevin Heist, R. Kenneth Czambel, Robert T. Rubin Jan 1997

Neuroendocrine Aspects Of Primary Endogenous Depression Xv. Mathematical Modeling Of Nocturnal Melatonin Secretion In Major Depressives And Normal Controls, L. Kathleen Sekula, Joseph F. Lucke, E. Kevin Heist, R. Kenneth Czambel, Robert T. Rubin

Joseph Lucke

We previously reported a trend toward a higher mean nocturnal serum melatonin (MEL) concentration, based on 30-min blood sampling over 24 h, in 23 female definite endogenous depressives compared to 23 matched normal female control subjects, and no significant difference in 15 male depressives compared to their controls (Rubin et al., 1992). In both groups of patients vs. their controls, there also were trends toward an earlier MEL rise time, by about 30 min, and a later MEL peak time, by about 90 min. Because the offset of MEL secretion was not estimated in that study, the total duration of …

Go to article

U.S. Adherence To Its Agenda 21 Commitments: A Five-Year Review, John C. Dernbach Jan 1997

U.S. Adherence To Its Agenda 21 Commitments: A Five-Year Review, John C. Dernbach

John C. Dernbach

No abstract provided.

Go to article

The Unfocused Regulation Of Toxic And Hazardous Pollutants, John C. Dernbach Jan 1997

The Unfocused Regulation Of Toxic And Hazardous Pollutants, John C. Dernbach

John C. Dernbach

No abstract provided.

Go to article

Identification Of A Fish Host Of The Inflated Heelsplitter Potamilus Inflatus( Bivalvia: Unionidae) With A Description Of Its Glochidium, Kevin J. Roe, Andrew M. Simons, Paul Hartfield Jan 1997

Identification Of A Fish Host Of The Inflated Heelsplitter Potamilus Inflatus( Bivalvia: Unionidae) With A Description Of Its Glochidium, Kevin J. Roe, Andrew M. Simons, Paul Hartfield

Kevin J. Roe

A survey of the fishes of the lack Warrior River was undertaken to determine fish host(s) of the federally threatened inflated heelsplitter, Potamilus inflatus. Seven hundred-twenty individual fishes representing 30 species were examined; mussel glochidia were found on 10 individual fishes representing nine species. Potamilus inflatus glochidia were only found infesting one freshwater drum (Aplodinotus grunniens), which is concordant with previous findings for the genus Potamilus. The morphology of P. inflatus glochidia is described and compared to P. purpuratus.

Go to article

Processing Small Quantities Of Walnut Logs For Lumber And Craft Items, Douglas D. Stokke, Peter Y. S. Chen, J. W. Van Sambeek Jan 1997

Processing Small Quantities Of Walnut Logs For Lumber And Craft Items, Douglas D. Stokke, Peter Y. S. Chen, J. W. Van Sambeek

Douglas D. Stokke

Many walnut plantation owners and woodworking hobbyists would like to process small quantities of walnut logs into lumber and discs for furniture and craft items. Various options exist for sawing, drying, and processing small diameter or short logs into lumber and cross-sectional discs. Portable band saws are a safe and inexpensive log breakdown option to commercial headsaw mills. Processing using the saw-dry-rip method will yield higher quantities of usable lumber from small diameter logs than the conventional saw-rip-dry method. Small quantities of lumber and discs can be inexpensively air dried under shelters or open sheds followed by approximately 15 to …

Go to article

The Silviculture-Wood Quality Connection In Eastern Black Walnut, Douglas D. Stokke, Bruce E. Cutter, John E. Phelps Jan 1997

The Silviculture-Wood Quality Connection In Eastern Black Walnut, Douglas D. Stokke, Bruce E. Cutter, John E. Phelps

Douglas D. Stokke

The known effects of silvicultural practices on eastern black walnut (Juglans nigra L.) wood quality are reviewed. Since desirable quality differs from end user to end user, no specific recommendations are made.

Go to article

Risk Analysis Of Black Walnut And Red Oak Plantations, Douglas D. Stokke, Stephen H. Kolison Jr., Jianbang Gan Jan 1997

Risk Analysis Of Black Walnut And Red Oak Plantations, Douglas D. Stokke, Stephen H. Kolison Jr., Jianbang Gan

Douglas D. Stokke

Risks and uncertainties are prevalent in timber production due to the nature and length of the production process. This paper examines the volatility of timber prices and the effects of some economic uncertainties and risks such as fluctuations in timber prices and the interest rate on the economic returns of black walnut and red oak plantations. Historical patterns of timber prices for black walnut and oaks are investigated and compared with those of other timber species and stock price. The sensitivity of economic returns from black walnut and red oak plantations to changes in timber prices and the discount rate …

Go to article

A Computationally-Based Hazard Identification Algorithm That Incorporates Ligand Flexibility. 1. Identification Of Potential Androgen Receptor Ligands, Steven P. Bradbury, Ovanes Mekenyan, Julian Ivanov, Stoyan Karabunarliev, Gerald T. Ankley, Walter Karcher Jan 1997

A Computationally-Based Hazard Identification Algorithm That Incorporates Ligand Flexibility. 1. Identification Of Potential Androgen Receptor Ligands, Steven P. Bradbury, Ovanes Mekenyan, Julian Ivanov, Stoyan Karabunarliev, Gerald T. Ankley, Walter Karcher

Steven P. Bradbury

To advance techniques for screening large data sets of diverse structures for toxicologically active compounds, an algorithm was developed that is not dependent upon a predetermined and specified toxicophore or an alignment of conformers to a lead compound. Instead, the approach provides the means to identify and quantify specific global and local stereoelectronic characteristics associated with active compounds through a comparison of energeticallyreasonable conformer distributions for specific descriptors. To illustrate the algorithm, the stereoelectronic requirements associated with the binding affinity of 28 steroidal and non-steroidal ligands to the androgen receptor were defined. Common ranges of interatomic distances, atomic charges, and …

Go to article

Influence Of Geographic Origin And Soil Properties On Color Of Black Walnut Veneer, Douglas D. Stokke, Edward C. Workman Jr., John E. Phelps, Felix Ponder Jr. Jan 1997

Influence Of Geographic Origin And Soil Properties On Color Of Black Walnut Veneer, Douglas D. Stokke, Edward C. Workman Jr., John E. Phelps, Felix Ponder Jr.

Douglas D. Stokke

Walnut veneer frorn sites in Missouri, Illinois, and Indiana was analyzed for color attributes and chemical properties. Veneer color also was compared to an industry color standard. Soil chemical and physical properties were measured on selected sites in each state. In general, walnut trees grown on soils with equal proportions of sand, silt, and clay have better veneer color attributes than trees grown on soils with high clay I sand or clay I silt ratios.

Go to article

The S0 State Of The Oxygen-Evolving Complex In Photosystem Ii Is Paramagnetic:  Detection Of An Epr Multiline Signal, Johannes Messinger, John H. Robblee, Edward Yu, Kenneth Sauer, Vittal K. Yachandra, Melvin P. Klein Jan 1997

The S0 State Of The Oxygen-Evolving Complex In Photosystem Ii Is Paramagnetic:  Detection Of An Epr Multiline Signal, Johannes Messinger, John H. Robblee, Edward Yu, Kenneth Sauer, Vittal K. Yachandra, Melvin P. Klein

Edward Yu

The photosynthetic oxidation of water to molecular oxygen is energetically driven by light-induced charge separations in the reaction center of photosystem II (PS II). The reaction is catalyzed by a tetranuclear manganese cluster contained in the oxygen-evolving complex (OEC). The OEC cycles through five different redox states termed S0 to S4, with S1 being the darkstable state. Oxygen is released during the S4 f S0 transition.1 The removal of one electron from the OEC on each S state transition leads to the idea that alternate S states should be paramagnetic because of their odd-electron number. The multiline EPR signal, which …

Go to article

Nonlinear Dependence Of Lb On Lfir And Mh2 Among Spiral Galaxies And The Effects Of Tidal Interaction, J Perea, A Del Olmo, L Verdes-Montenegro, Min S. Yun Jan 1997

Nonlinear Dependence Of Lb On Lfir And Mh2 Among Spiral Galaxies And The Effects Of Tidal Interaction, J Perea, A Del Olmo, L Verdes-Montenegro, Min S. Yun

Min S. Yun

Through the study of a carefully selected sample of isolated spiral galaxies, we have established that two important global physical quantities for tracing star-forming activities, LFIR and MH2, have a nonlinear dependence on another commonly cited global quantity, LB. Furthermore, we show that simple power-law relations can effectively describe these nonlinear relations for spiral galaxies spanning 4 orders of magnitude in FIR and MH2, and nearly 3 orders of magnitude in LB. While the existence of a nonlinear dependence of MH2 (assuming a constant CO-to-H2 conversion) and LFIR on optical luminosity (LB) has been previously noted in the literature, an …

Go to article

First Prev Next Last