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Articles 20491 - 20520 of 21971

Full-Text Articles in Physical Sciences and Mathematics

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.


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.


Emisja Metali Ciężkich Ze Spalania Odpadów Niebezpiecznych, Robert Oleniacz, Marian Mazur, Marek Bogacki Dec 1997

Emisja Metali Ciężkich Ze Spalania Odpadów Niebezpiecznych, Robert Oleniacz, Marian Mazur, Marek Bogacki

Robert Oleniacz

The paper presents the results of measurements of air emissions of heavy metals from hazardous waste incineration in a multiple hearth furnace and a rotary kiln incinerator equipped with a single wet flue gas cleaning systems. In the multiple hearth furnace an industrial sewage sludge (from coke industry) was being incinerated. In the rotary kiln such wastes were being incinerated as: waste paints, varnish and lubricant, coal tars waste, contaminated cleaning rags, sawdust and used gloves, waste resins and plastics, rubber waste, outdated pharmaceuticals and medicines, and hospital waste. The research allowed us to determine the levels of pollutant concentrations …


Zastosowanie Modelu "Skrzynki" Do Oceny Poziomu Stężeń Zanieczyszczeń Komunikacyjnych W Przyziemnej Warstwie Atmosfery, Marek Bogacki, Marian Mazur, Robert Oleniacz Dec 1997

Zastosowanie Modelu "Skrzynki" Do Oceny Poziomu Stężeń Zanieczyszczeń Komunikacyjnych W Przyziemnej Warstwie Atmosfery, Marek Bogacki, Marian Mazur, Robert Oleniacz

Robert Oleniacz

Road transport is an essential source of nitrogen oxides (NOx), carbon monoxide (CO) and reactive hydrocarbons (RHC) emissions to atmosphere. Quantity and chemical constitution of emitted substances and meteorological conditions determine the level of ozon (O3) concentration forming as a result of photochemical reactions. The method presented in the paper consists in designation of quantity and chemical constitution of substances emitted from mo-bile sources and special mathematical modeling of physical and chemical transformations that take place in the lowest atmospheric layer.

English title: The use of box model to estimate the size of traffic pollutant concentrations in the lowest atmospheric …


Dimethyl (±)-(1s*,2r*,3s*)-[3-Phenyl-1-(N-Phenylcarbamoyloxy)-2, 3-Epoxypropyl]-Phosphonate, T. Boehlow, A. De La Cruz, N. P. Rath, C. D. Spilling Dec 1997

Dimethyl (±)-(1s*,2r*,3s*)-[3-Phenyl-1-(N-Phenylcarbamoyloxy)-2, 3-Epoxypropyl]-Phosphonate, T. Boehlow, A. De La Cruz, N. P. Rath, C. D. Spilling

Christopher Spilling

The crystal structure of the racemic title compound, C18H20NO6P, m.p. 428-431 K, has been determined by X-ray diffraction. The title compound consists of a tetrahedral P atom bonded to two methoxy groups, and an alkyl chain. The alkyl chain was substituted at position 1 with a carbamate and with an epoxide at positions 2 and 3. The relative configuration of the 1-carbamate and 2,3-epoxide substituents was confirmed as anti (1S,2R,3S). The crystal structure contains an enantiomeric pair with two intermolecular hydrogen bonds in a 14-membered ring. The hydrogen bonds are formed between the P=O of one enantiomer and the N-H …


Dimethyl (±)-(1s*,2r*,3s*)-[3-Phenyl-1-(N-Phenylcarbamoyloxy)-2, 3-Epoxypropyl]-Phosphonate, T. Boehlow, A. De La Cruz, Nigam P. Rath, C. D. Spilling Dec 1997

Dimethyl (±)-(1s*,2r*,3s*)-[3-Phenyl-1-(N-Phenylcarbamoyloxy)-2, 3-Epoxypropyl]-Phosphonate, T. Boehlow, A. De La Cruz, Nigam P. Rath, C. D. Spilling

Nigam Rath

The crystal structure of the racemic title compound, C18H20NO6P, m.p. 428-431 K, has been determined by X-ray diffraction. The title compound consists of a tetrahedral P atom bonded to two methoxy groups, and an alkyl chain. The alkyl chain was substituted at position 1 with a carbamate and with an epoxide at positions 2 and 3. The relative configuration of the 1-carbamate and 2,3-epoxide substituents was confirmed as anti (1S,2R,3S). The crystal structure contains an enantiomeric pair with two intermolecular hydrogen bonds in a 14-membered ring. The hydrogen bonds are formed between the P=O of one enantiomer and the N-H …


34. Shunsuke Murahashi, Otto Vogl, Mikiharu Kamachi, Koichi Hatada Dec 1997

34. Shunsuke Murahashi, Otto Vogl, Mikiharu Kamachi, Koichi Hatada

Otto Vogl

No abstract provided.


Icris '96: Controlled Organization And Molecular Dynamics Of Polymers, Uji, Kyoto, Japan, Otto Vogl, Masaki Tsuji Dec 1997

Icris '96: Controlled Organization And Molecular Dynamics Of Polymers, Uji, Kyoto, Japan, Otto Vogl, Masaki Tsuji

Otto Vogl

No abstract provided.


Statistics For Logisticians, Caroline Lubert Nov 1997

Statistics For Logisticians, Caroline Lubert

Caroline P Lubert

No abstract provided.


Windows 3.X Vs. Windows 95: Get Your Ring-Side Seat, Sonya Shepherd Nov 1997

Windows 3.X Vs. Windows 95: Get Your Ring-Side Seat, Sonya Shepherd

Sonya S. Gaither

No abstract provided.


Combining Multi-Attribute Utility And Geographic Information For Boundary Decisions: An Application To Park Planning, Jeffrey Keisler, Ronald Sundell Nov 1997

Combining Multi-Attribute Utility And Geographic Information For Boundary Decisions: An Application To Park Planning, Jeffrey Keisler, Ronald Sundell

Jeffrey Keisler

The quality and value of an area depend primarily on what is found within
its designated boundaries. To determine the value of such areas in terms of boundaries,
we have developed a methodology for integrating multi-attribute utility functions with
spatial analysis so that desirable, or appropriate, boundaries can be determined on the
basis of the goals and objectives for the park. The key to successful evaluation is the
development of measures for what decision makers value, rather than merely using
what is easily measured. In a detailed example for planning of national parks, the
fundamental objectives are conservation and societal …


Combining Multi-Attribute Utility And Geographic Information For Boundary Decisions: An Application To Park Planning, Jeffrey Keisler, Ronald Sundell Nov 1997

Combining Multi-Attribute Utility And Geographic Information For Boundary Decisions: An Application To Park Planning, Jeffrey Keisler, Ronald Sundell

Jeffrey Keisler

The quality and value of an area depend primarily on what is found within its designated boundaries. To determine the value of such areas in terms of boundaries, we have developed a methodology for integrating multi-attribute utility functions with spatial analysis so that desirable, or appropriate, boundaries can be determined on the basis of the goals and objectives for the park. The key to successful evaluation is the development of measures for what decision makers value, rather than merely using what is easily measured. In a detailed example for planning of national parks, the fundamental objectives are conservation and societal …


Photolithographic Patterning Of Vacuum-Deposited Organic Light Emitting Devices, Peifang Tian, P. E. Burrows, S. E. Forrest Nov 1997

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

Peifang Tian

We demonstrate a photolithographic technique to fabricate vacuum-deposited organic light emitting devices. Photoresist liftoff combined with vertical deposition of the emissive organic materials and the metal cathode, followed by oblique deposition of a metal cap, avoids the use of high processing temperatures and the exposure of the organic materials to chemical degradation. The unpackaged devices show no sign of deterioration in room ambient when compared with conventional devices fabricated using low-resolution, shadow mask patterning. Furthermore, the devices are resistant to rapid degradation when operated in air for extended periods. This work illustrates a potential foundation for the volume production of …


A Vegetation Based Approach To Biodiversity Gap Analysis In The Agastyamalai Region, Western Ghats, India, B. R. Ramesh, Shaily Menon, Kamaljit S. Bawa Nov 1997

A Vegetation Based Approach To Biodiversity Gap Analysis In The Agastyamalai Region, Western Ghats, India, B. R. Ramesh, Shaily Menon, Kamaljit S. Bawa

Shaily Menon

Protected areas in India have historically been established on an ad hoc basis with little attention to the conservation value of an area. This study focuses on a set of protected areas in the Agastyamalai region of the Western Ghats (WG), India. We examine forest loss and land-use changes in the study area from the early 1900s to 1960 and from 1960 to 1990. We use GIS to perform a biodiversity gap analysis of the protected areas in the study site. We produce a detailed map of existing floristic types and use it to generate layers corresponding to floristic species …