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1998

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Articles 2611 - 2634 of 2634

Full-Text Articles in Physical Sciences and Mathematics

Active Tectonics And Ultrahigh-Pressure Rocks, Ann Blythe Dec 1997

Active Tectonics And Ultrahigh-Pressure Rocks, Ann Blythe

Ann Blythe

This chapter compares modern exhumation and surface uplift rates with the rates needed for the preservation of ultrahigh pressure (UHP) metamorphic rocks. The highest recorded exhumation rates of ~ 5–10 mm/a are inferred from isotopic and fission-track analyses in the Himalaya, Southern Alps of New Zealand, and D’Entrecasteaux Islands. Similar rates (~7 mm/a) of surface uplift are measured from leveling surveys in Nepal and correlations of marine terraces in the Southern Alps. In Nepal, however, this surface uplift rate is occurring despite erosion, and the true rate of surface uplift is probably considerably higher. In restraining bends along the San …


The Harmonic Oscillator Propagator, Br Holstein Dec 1997

The Harmonic Oscillator Propagator, Br Holstein

Barry R Holstein

The Feynman propagator for the harmonic oscillator is evaluated by a variety of path-integral-based means.


Answer To Question #76. Neutrino Mass And Helicity, Br Holstein Dec 1997

Answer To Question #76. Neutrino Mass And Helicity, Br Holstein

Barry R Holstein

No abstract provided.


Short Time Fourier Transform, Integral Wavelet Transform, And Wavelet Functions Associated With Splines, Tian-Xiao He Dec 1997

Short Time Fourier Transform, Integral Wavelet Transform, And Wavelet Functions Associated With Splines, Tian-Xiao He

Tian-Xiao He

In this article, we discuss short time Fourier transforms, integral wavelet transforms, and wavelet series expansions associated with spline functions in shift-invariant spaces of B-splines. A recurrence relation formula and the corresponding algorithm about the B-wavelets are also given.


Isolation And Structure Of Sc2@C74 And Sc2@C76, Harry Dorn, Steven Stevenson, Paul Burbank, Kim Harich, Z. Sun, T. Glass, Mark Anderson, Donald Bethune, M. Sherwood Dec 1997

Isolation And Structure Of Sc2@C74 And Sc2@C76, Harry Dorn, Steven Stevenson, Paul Burbank, Kim Harich, Z. Sun, T. Glass, Mark Anderson, Donald Bethune, M. Sherwood

Mark R. Anderson

No abstract is currently available.


High Performance Liquid Chromatographic Analysis Of Amino Acid- And Dipeptide-Derived Chloramines, Thomas Goyne, Suzanne Furness-Green, Tracy Inskeep, Jennifer Starke, Lu Ping, Heather Greenleaf-Schumann Dec 1997

High Performance Liquid Chromatographic Analysis Of Amino Acid- And Dipeptide-Derived Chloramines, Thomas Goyne, Suzanne Furness-Green, Tracy Inskeep, Jennifer Starke, Lu Ping, Heather Greenleaf-Schumann

Thomas Goyne

No abstract provided.


Resistivity Determination From Small Crystallites, S. Hyun, M. Thorpe, B. Golding, M. Jaeger, Anthony Day Dec 1997

Resistivity Determination From Small Crystallites, S. Hyun, M. Thorpe, B. Golding, M. Jaeger, Anthony Day

Anthony Roy Day

We determine the resistivity of small micrometer-sized conductors with arbitrary shapes. It is shown that with n terminals attached to the sample, there are n(n􏰝1)/2 independent measurements of the resistance that can be made; from which the sample resistivity and the contact resistances can be extracted. An image of the sample is digitized and a finite element analysis is used to determine the geometrical factors that arise from the nonuniform current flow and hence control the resistance measurements. It is shown that all the elements of the resistance matrix for the sample are generated from the diagonal elements alone for …


Statistical Analysis Of Reliability, Maintainability And Supportability Data, Caroline Lubert Dec 1997

Statistical Analysis Of Reliability, Maintainability And Supportability Data, Caroline Lubert

Caroline P Lubert

No abstract provided.


Using An E-Mail Tutorial And Student Seminars To Improve An Intermediate-Level Undergraduate Physics Course, Janet Scheel Dec 1997

Using An E-Mail Tutorial And Student Seminars To Improve An Intermediate-Level Undergraduate Physics Course, Janet Scheel

Janet D. Scheel

The authors revised the junior-level classical mechanics course at Cornell University to incorporate asynchronous, autonomous, and group learning. We created an E-mail tutorial and a student seminar. We will first discuss the theoretical background for these changes and then describe the results of their implementation over a period of three years.


Photolithographic Patterning Of Vacuum-Deposited Organic Light Emitting Devices, Peifang Tian, P. Burrows, B. Bulovic, S. Forrest Dec 1997

Photolithographic Patterning Of Vacuum-Deposited Organic Light Emitting Devices, Peifang Tian, P. Burrows, B. Bulovic, S. Forrest

Peifang Tian

No abstract provided.


Longitudinal Study Of Dental Development In Chimpanzees Of Known Chronological Age: Implications For Understanding The Age At Death Of Plio-Pleistocene Hominids, Robert Anemone, Mark Mooney Dec 1997

Longitudinal Study Of Dental Development In Chimpanzees Of Known Chronological Age: Implications For Understanding The Age At Death Of Plio-Pleistocene Hominids, Robert Anemone, Mark Mooney

Robert L. Anemone

Reconstruction of life history variables of fossil hominids on the basis of dental development requires understanding of and comparison with the pattern and timing of dental development among both living humans and pongids. Whether dental development among living apes or humans provides a better model for comparison with that of Plio-Pleistocene hominids of the genus Australopithecus remains a contentious point. This paper presents new data on chimpanzees documenting developmental differences in the dentitions of modern humans and apes and discusses their significance in light of recent controversies over the human or pongid nature of australopithecine dental development. Longitudinal analysis of …


Characteriation Of Bulk, Polycrystalline Indium Nitride Grown Of Subatmospheric Pressures, Jeffrey Dyck, Kathleen Kash, Kwieseon Kim, Walter Lambrecht, Cliff Hayman, Alberto Argoitia, Michael Grossner, Willie Zhou, John Angus Dec 1997

Characteriation Of Bulk, Polycrystalline Indium Nitride Grown Of Subatmospheric Pressures, Jeffrey Dyck, Kathleen Kash, Kwieseon Kim, Walter Lambrecht, Cliff Hayman, Alberto Argoitia, Michael Grossner, Willie Zhou, John Angus

Jeffrey Dyck

Polycrystalline, wurtzitic indium nitride was synthesized by saturating indium metal with atomic nitrogen from a microwave plasma source. Plasma synthesis avoids the high equilibrium pressures required when molecular nitrogen is used as the nitrogen source. Two types of growth were observed: 1) small amounts of indium nitride crystallized from the melt during cooling and 2) hexagonal platelets formed adjacent to the In metal source on the crucible sides. The mechanism of this latter growth is not established, but may involve transport of indium as a liquid film. The crystals were characterized by electron diffraction, X-ray diffraction, elemental analysis, scanning electron …


Measurements Of Kleinman-Disallowed Hyperpolarizability In Conjugated Chiral Molecules, S. Hubbard, R. Petschek, K. Singer, N. D'Sidocky, C. Hudson, Liang-Chy Chien, C. Henderson, P. Cahill Dec 1997

Measurements Of Kleinman-Disallowed Hyperpolarizability In Conjugated Chiral Molecules, S. Hubbard, R. Petschek, K. Singer, N. D'Sidocky, C. Hudson, Liang-Chy Chien, C. Henderson, P. Cahill

Liang-Chy Chien

We have designed a hyper-Rayleigh scattering scheme to measure six scalar invariants of the squared hyperpolarizability tensor beta(2). OUT theoretical approach expresses the rotational invariants of the irreducible beta components as scalars, which eliminates the need for difficult frame transformations. We applied our scheme to several conjugated chiral molecules and found that there are significant Kleinman-disallowed pseudotensor contributions to their hyperpolarizability. These components, along with a large optical rotation and the results of quantum-chemical calculations, indicate a handed nonplanar delocalization of the charge-transfer system in such molecules as predicted by quantum-chemical calculations and are expected to lead to macroscopic second-harmonic …


Dependability Analysis Of Redundant Systems, Caroline Lubert Dec 1997

Dependability Analysis Of Redundant Systems, Caroline Lubert

Caroline P Lubert

No abstract provided.


On Complex Interpolation And Spectral Continuity, Karen Saxe Dec 1997

On Complex Interpolation And Spectral Continuity, Karen Saxe

Karen Saxe

No abstract provided.


Tight-Binding Simulations Of Argon Cation Clusters, Guillermo A. Morales, Jessica Faulkner, Randall W. Hall Dec 1997

Tight-Binding Simulations Of Argon Cation Clusters, Guillermo A. Morales, Jessica Faulkner, Randall W. Hall

Randall W. Hall

A simple, semiempirical model was used to study the ground and excited stateproperties of argon cation clusters at 60 K. The model is a tight-binding Hamiltonian whose parameters are determined from atomic and diatomic properties.Monte Carlo simulations were used to calculate the average properties of these clusters. The photoabsorptionspectrum was in good agreement with previous calculations and experiments. The splitting of the photoabsorptionspectrum for clusters with greater than 14 atoms was investigated. The two excited states corresponding to the splitting arise from a 3-atom ion core, perturbed by a 4th atom, with solvation from the remaining atoms. The perturbation of …


Dynamic Control Models As State Abstractions, Jefferson A. Coelho, Roderic Grupen Dec 1997

Dynamic Control Models As State Abstractions, Jefferson A. Coelho, Roderic Grupen

Roderic Grupen

This work proposes a methodology for the construction of state abstraction from a set of empirically derived models of system behavior. The idea is to treat the agent in its environment as a dynamical system and augment its observation space with contextual cues extracted empirically as the agent exercises each element out of the set of available control policies--the control bias. Contextual cues are provided by the correlation between dynamic features of the agent-environment interaction and agent performance. The resulting state abstraction (observations + context information) defines also a temporal abstraction, and offers interesting answers to some of the issues …


Biogeography Of The Late Paleocene Benthic Foraminiferal Extinction, Ellen Thomas Dec 1997

Biogeography Of The Late Paleocene Benthic Foraminiferal Extinction, Ellen Thomas

Ellen Thomas

During the Late Paleocene Thermal Maximum (LPTM) benthic foraminifera at middle bathyal and greater depths suffered extinction of 30-50% of species during a few thousand years. Extinction was less severe at neritic to upper bathyal depths, where temporary changes in faunal composition prevailed. Pre-extinction deep-sea faunas were cosmopolitan and diverse, and contained heavily calcified species. Immediate post-extinction faunas were more variable geographically, exhibited low diversity, and were dominated by thin-walled calcareous or agglutinated taxa, possibly because CaCO3 dissolution increased globally from neritic to abyssal depths just before the extinction. These assemblages were dominated either by long-lived taxa such as Nuttallides …


Ambiguity And Constraint In Mathematical Expression Recognition, Erik G. Learned-Miller, Paul A. Viola Dec 1997

Ambiguity And Constraint In Mathematical Expression Recognition, Erik G. Learned-Miller, Paul A. Viola

Erik G Learned-Miller

The problem of recognizing mathematical expressions differs significantly from the recognition of standard prose. While in prose significant constraints can be put on the interpretation of a character by the characters immediately preceding and following it, few such simple constraints are present in a mathematical expression. In order to make the problem tractable, effective methods of recognizing mathematical expressions will need to put intelligent constraints on the possible interpretations. The authors present preliminary results on a system for the recognition of both handwritten and typeset mathematical expressions. While previous systems perform character recognition out of context, the current system maintains …


Trench's Canonical Form For A Disconjugate $N$Th-Order Linear Difference Equation, William F. Trench, Bennette Harris, Robert Krueger Dec 1997

Trench's Canonical Form For A Disconjugate $N$Th-Order Linear Difference Equation, William F. Trench, Bennette Harris, Robert Krueger

William F. Trench

No abstract provided.


Additive Nonparametric Regression With Autocorrelated Errors, Michael S. Smith, C Wong, Robert Kohn Dec 1997

Additive Nonparametric Regression With Autocorrelated Errors, Michael S. Smith, C Wong, Robert Kohn

Michael Stanley Smith

A Bayesian approach is presented for nonparametric estimation of an additive regression model with autocorrelated errors. Each of the potentially nonlinear components is modelled as a regression spline using many knots, while the errors are modelled by a high order stationary autoregressive process parameterised in terms of its autocorrelations. The distribution of significant knots and partial autocorrelations is accounted for using subset selection. Our approach also allows the selection of a suitable transformation of the dependent variable. All aspects of the model are estimated simultaneously using Markov chain Monte Carlo. It is shown empirically that the proposed approach works well …


Conjugate Schema And Basis Representation Of Crossover And Mutation Operators, S. Kazadi Dec 1997

Conjugate Schema And Basis Representation Of Crossover And Mutation Operators, S. Kazadi

Sanza Kazadi

In genetic search algorithms and optimization routines, the representation of the mutation and crossover operators are typically defaulted to the canonical basis. We show that this can be influential in the usefulness of the search algorithm. We then pose the question of how to find a basis for which the search algorithm is most useful. The conjugate schema is introduced as a general mathematical construct and is shown to separate a function into smaller dimensional functions whose sum is the original function. It is shown that conjugate schema, when used on a test suite of functions, improves the performance of …


Strategies Of Representation, Relationship, And Resistance: British Women Travelers And Mormon Plural Wives, C. 1870-1890, Karen M. Morin, J.K. Guelke Dec 1997

Strategies Of Representation, Relationship, And Resistance: British Women Travelers And Mormon Plural Wives, C. 1870-1890, Karen M. Morin, J.K. Guelke

Karen M. Morin

During the 1870s and 1880s, several British women writers traveled by transcontinental railroad across the American West via Salt Lake City, Utah, the capital of the Church of Jesus Christ of Latter-day Saints, or Mormons. These women subsequently wrote books about their travels for a home audience with a taste for adventures in the American West, and particularly for accounts of Mormon plural marriage, which was sanctioned by the Church before 1890. "The plight of the Mormon woman," a prominent social reform and literary theme of the period, situated Mormon women at the center of popular representations of Utah during …


Exo- And Endo-Tricarbonyl[(4b,5,6,7,8,8a-Η)-Cis-N-Methyl-2,3,4,4a,9,9a-Hexahydro-1h- Carbazole]Chromium(0), Nigam Rath, F. Christopher Pigge, Shiyue Fang Dec 1997

Exo- And Endo-Tricarbonyl[(4b,5,6,7,8,8a-Η)-Cis-N-Methyl-2,3,4,4a,9,9a-Hexahydro-1h- Carbazole]Chromium(0), Nigam Rath, F. Christopher Pigge, Shiyue Fang

Nigam Rath

Acid-mediated hydride reduction of tricarbonyl([eta]6-N-methyl-1,2,3,4-tetrahydrocarbazole)chromium(0) affords either the cis-fused exo-hexahydrocarbazole chromium(0) complex {[Cr(C13H17N)(CO)3], (I)} exclusively, or a separable mixture of (I) and the endo-isomer {[Cr(C13H17N)(CO)3], (II)}, depending upon the choice of hydride donor. The conformations of the hexahydrocarbazole systems differ in the orientation of the indoline moiety with respect to the saturated hexahydrocarbazole rings. The isolation of the exo isomer is unusual, as this complex arises via reaction at the sterically more hindered endo face of the coordinated ligand.