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

Physical Sciences and Mathematics Commons™

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

Selected Works

Discipline
Keyword
Publication Year
Publication
File Type

Articles 16231 - 16260 of 16838

Full-Text Articles in Physical Sciences and Mathematics

Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman Mar 1997

Two-Photon Optogalvanic Spectra Of Argon: Odd Parity Rydberg States, Naveed Piracha, M. Baig, S. Khan, B. Suleman

Naveed K. Piracha

Extensive new data on the odd-parity, single-colour, two-photon optogalvanic spectra of argon in the visible region is reported using an excimer-pumped dye laser in conjunction with an argon discharge cell. The experimental technique enables us to record a pure two-photon spectrum in a region which is dominated by one-photon transitions. A large number of two-photon transitions, originating from the two metastable states [...] and [...] to the excited states of configurations [...] (J=0, 2) and [...] (J = 0 - 4) of argon, has been recorded and arranged into 10 Rydberg series. The interchannel interactions among the [...] and the …

Go to article

Backward Stimulated Raman Scattering Of A Modulated Laser Pulse In Plasmas, Nikolai E. Andreev, Serguei Y. Kalmykov Mar 1997

Backward Stimulated Raman Scattering Of A Modulated Laser Pulse In Plasmas, Nikolai E. Andreev, Serguei Y. Kalmykov

Serge Youri Kalmykov

The specific features of backward stimulated Raman scattering (BSRS) of a short modulated (multi-frequency) laser pulse in underdense plasmas are studied. The effect of resonant suppression of the BSRS of higher frequency pulse components is explored. For an arbitrary pair of pulse components, in the conditions of weak coupling, it is demonstrated that the backscattering of a higher frequency laser pulse component is a five-wave resonant process at a frequency difference between the components close to the double plasma frequency. In the conditions of strong coupling the backscattering of neither pulse component is suppressed and the spectrum of the instability …

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

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

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

Review Of Mathematica 3.0, Stan Wagon Dec 1996

Review Of Mathematica 3.0, Stan Wagon

Stan Wagon, Retired

No abstract provided.

Go to article

Software Reuse: Architecture, Process And Organization For Business Success, Ivar Jacobson, Martin Griss, Patrik Jonsson Dec 1996

Software Reuse: Architecture, Process And Organization For Business Success, Ivar Jacobson, Martin Griss, Patrik Jonsson

Martin L Griss

No abstract provided.

Go to article

Constraint Satisfaction Methods For Generating Valid Cuts, John Hooker Dec 1996

Constraint Satisfaction Methods For Generating Valid Cuts, John Hooker

John Hooker

No abstract provided.

Go to article

Statistics For Logisticians, Caroline Lubert Dec 1996

Statistics For Logisticians, Caroline Lubert

Caroline P Lubert

No abstract provided.

Go to article

A Niobium(V) Complex With Mixed O,S-Donor Ligands. Synthesis, Structure And Properties Of The Anion Tris(2-Mercapto-4-Methylphenolato)Niobate(V), Paul Challen, Diane Peapus, Karen Magnes Dec 1996

A Niobium(V) Complex With Mixed O,S-Donor Ligands. Synthesis, Structure And Properties Of The Anion Tris(2-Mercapto-4-Methylphenolato)Niobate(V), Paul Challen, Diane Peapus, Karen Magnes

Paul R. Challen

Reaction of Nb(OEt)5 with 2-mercapto-4-methylphenol (mmpH2) in the presence of triethylamine gave the mononuclear tris complex (Et3NH)[Nb(mmp)3] which was structurally characterized. The coordination geometry around the niobium is between octahedral and trigonal prismatic, with a twist angle of 41.5°. The mercaptophenolate ligands are arranged around the metal in a “propeller” fashion. (Et3NH)[Nb(mmp)3] was characterized by IR, 1H NMR and UV-vis spectroscopies, and cyclic voltammetry. A reversible reduction wave found at −1.03 V is for reduction to the NbIV complex.

Go to article

Effectiveness Of The Protected Area Network In Biodiversity Conservation: A Case-Study Of Meghalaya State, M. Latif Khan, Shaily Menon, Kamaljit Bawa Dec 1996

Effectiveness Of The Protected Area Network In Biodiversity Conservation: A Case-Study Of Meghalaya State, M. Latif Khan, Shaily Menon, Kamaljit Bawa

Shaily Menon

The North-Eastern region of India is significant for biodiversity conservation because of its floristic richness and high levels of endemism. Deforestation levels are high in the region due to anthropogenic pressures. We accessed various literature sources to create a database for Meghalaya state containing information on plant species, habit, altitudinal distribution, endemism, and endangered status. Information on the existing protected area network (type, extent, and altitudinal representation) was added to the database. The database was used to assess the effectiveness of the existing protected area network in conserving the floristic biodiversity of the state. Of a total of 3331 plant …

Go to article

Activities Of The Ilo In The Field Of The Environment, Cleopatra Doumbia-Henry Dec 1996

Activities Of The Ilo In The Field Of The Environment, Cleopatra Doumbia-Henry

Cleopatra Doumbia-Henry

No abstract provided.

Go to article

Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash Dec 1996

Synthesis Of Bulk, Polycrystalline Gallium Nitride At Low Pressures, Alberto Argoitia, John Angus, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash

Jeffrey Dyck

Bulk, polycrytalline gallium nitride was crystallized from gallium saturated with nitrogen obtained from a microwave electron cyclotron resonance source. The polycrystalline samples are wurtzitic and n-type. Well-faceted crystals give near-band-edge and yellow band photo-luminescence at both 10K and 300K. The results show that atomic nitrogen is an attractive alternative to high pressure molecular nitrogen for saturation of gallium with nitrogen for synthesis of bulk gallium nitride.

Go to article

Computer System For Simulating Physical Processes Using Multiple Integer State Vectors Us:5594671, Hudong Chen, Peter Churchill, Robert Iannucci, Kim Molvig, Gregory Papadopoulos, Stephen Remondi, Christopher Teixeira, Kenneth Traub Dec 1996

Computer System For Simulating Physical Processes Using Multiple Integer State Vectors Us:5594671, Hudong Chen, Peter Churchill, Robert Iannucci, Kim Molvig, Gregory Papadopoulos, Stephen Remondi, Christopher Teixeira, Kenneth Traub

Robert A Iannucci

No abstract provided.

Go to article

Essential Laminations In Graph Manifolds, Ramin Naimi, Mark Brittenham, Rachel Roberts Dec 1996

Essential Laminations In Graph Manifolds, Ramin Naimi, Mark Brittenham, Rachel Roberts

Ramin Naimi

No abstract provided.

Go to article

Voltammetric Studies Of Mn@C82, Mark Anderson, Harry Dorn, Paul Burbank, James Gibson Dec 1996

Voltammetric Studies Of Mn@C82, Mark Anderson, Harry Dorn, Paul Burbank, James Gibson

Mark R. Anderson

The voltammetry for a series of related endohedral metallofullerenes is reported. It is found that as additional metal atoms are inserted into the fullerene cage, the first reduction of the metallofullerenes shifts to more negative potentials. This is consistent with more charge being transferred to the fullerene cage from the additional metal atom; however, the magnitude of the shift is much smaller than expected.

Go to article

Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash Dec 1996

Growth Of Bulk, Polycrystalline Gallium And Indium Nitride At Sub-Atmospheric Pressures, John Angus, Alberto Argoitia, Cliff Hayman, Long Wang, Jeffrey Dyck, Kathleen Kash

Jeffrey Dyck

Bulk polycrystalline gallium nitride and indium nitride were crystallized at sub-atmospheric pressures by saturating the pure metals with nitrogen from a microwave electron cyclotron resonance source. Saturation of Ga/In melts with nitrogen led only to the crystallization of gallium nitride. The polycrystralline samples were wurtzitic. The gallium nitride was well faceted, with narrow Raman lineshapes, and showed near-band-edge and yellow band photo-luminescence at both 4K and 300K. The indium nitirde was formed in smaller amounts, was less well faceted, and showed no photoluminescence.

Go to article

Alte Und Neue Ungeloste Probleme In Der Zahlentheorie Und Geoetrie Der Ebene (Online), Stan Wagon Dec 1996

Alte Und Neue Ungeloste Probleme In Der Zahlentheorie Und Geoetrie Der Ebene (Online), Stan Wagon

Stan Wagon, Retired

No abstract provided.

Go to article

The Linear Potential Propagator, Br Holstein Dec 1996

The Linear Potential Propagator, Br Holstein

Barry R Holstein

The Feynman propagator for the case of a linear potential is evaluated by a variety of means.

Go to article

Uniformly Adaptive Estimation For Models With Arma Errors, Douglas Steigerwald Dec 1996

Uniformly Adaptive Estimation For Models With Arma Errors, Douglas Steigerwald

Douglas G. Steigerwald

A semiparametric estimator based on an unknown density is uniformly adaptive if the expected loss of the estimator converges to the asymptotic expected loss of the maximum likelihood estimator based on the true density (MLE), and if convergence does not depend on either the parameter values or the form of the unknown density. Without uniform adaptivity, the asymptotic expected loss of the MLE need not approximate the expected loss of a semiparamteric estimator for any finite sample. I show that a two-step semiparametric estimator is uniformly adaptive for the parameters of nonlinear regression models with autoregressive moving average errors.

Go to article

Biodiversity Monitoring: The Missing Ingredient, Kamaljit Bawa, Shaily Menon Dec 1996

Biodiversity Monitoring: The Missing Ingredient, Kamaljit Bawa, Shaily Menon

Shaily Menon

With mounting losses in biological diversity, inventorying and monitoring of biodiversity to assess the magnitude and rate of losses are emerging as dominant themes in conservation biology. Inventorying has been defined as the surveying, sorting, cataloging, quantifying and mapping of entities ranging from genes to landscapes1 and monitoring has been defined as the surveillance of the compliance with or deviation from a predetermined standard2. Renner and Ricklefs3 argued that rushed inventories will compromise scientific rigor and have little influence on decision making. More recently, Stork et al.4 argued that losses in biological diversity are so severe that inventorying and monitoring …

Go to article

The Elastic Moduli Of Random Networks: Calculations, Anthony Day Dec 1996

The Elastic Moduli Of Random Networks: Calculations, Anthony Day

Anthony Roy Day

No abstract provided.

Go to article

Mathematica In Action., Stan Wagon Dec 1996

Mathematica In Action., Stan Wagon

Stan Wagon, Retired

No abstract provided.

Go to article

A Challenge Form Leningrad, Stan Wagon Dec 1996

A Challenge Form Leningrad, Stan Wagon

Stan Wagon, Retired

No abstract provided.

Go to article

What Is A Prime Number?, Stan Wagon, D. Schattschneider, R. Mabry Dec 1996

What Is A Prime Number?, Stan Wagon, D. Schattschneider, R. Mabry

Stan Wagon, Retired

No abstract provided.

Go to article

Constructing Essential Laminations In 2-Bridge Knot Surgered 3-Manifolds, Ramin Naimi Dec 1996

Constructing Essential Laminations In 2-Bridge Knot Surgered 3-Manifolds, Ramin Naimi

Ramin Naimi

A nontrivial knot that can be drawn with only two relative maxima in the vertical direction is called a 2-bridge knot, and one that can be drawn on a torus is called a torus knot. Loosely speaking, a lamination in a manifold M is a foliation of M, except that it can have a nonempty open complement in M, and very loosely speaking, the lamination is essential if each leaf of it L is incompressible, i.e. inclusion of L into M induces an injective homomorphism from π1(L) into π1(M). Our main result is: Theorem 2. Every 3-manifold obtained by surgery …

Go to article

Supportability Analysis Of Repairable Systems With Parallel Configurations, Caroline Lubert, J. Knezevic Dec 1996

Supportability Analysis Of Repairable Systems With Parallel Configurations, Caroline Lubert, J. Knezevic

Caroline P Lubert

No abstract provided.

Go to article

First Prev Next Last