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Articles 15871 - 15900 of 16838

Full-Text Articles in Physical Sciences and Mathematics

Translational And Rotational Diffusion In Stretched Water, P. A. Netz, Francis Starr, M. C. Barbosa, H. E. Stanley Dec 2001

Translational And Rotational Diffusion In Stretched Water, P. A. Netz, Francis Starr, M. C. Barbosa, H. E. Stanley

Francis Starr

No abstract provided.


Indexing For A Digital Library Of George Washington’S Manuscripts: A Study Of Word Matching Techniques, T. M. Rath, S. Kane, A. Lehman, E. Partridge, R. Manmatha Dec 2001

Indexing For A Digital Library Of George Washington’S Manuscripts: A Study Of Word Matching Techniques, T. M. Rath, S. Kane, A. Lehman, E. Partridge, R. Manmatha

R. Manmatha

In a multimedia world, one would like electronic access to all kinds of information. But a lot of important information still only exists on paper and it is a challenge to efficiently access or navigate this information even if it is scanned in. The previously proposed \word spotting" idea is an approach for accessing and navigating a collection of handwritten documents available as images using an index automatically generated by matching words as pictures. The most difficult task in solving this problem is the matching of word images. The quality of the aged documents and the variations in handwriting make …


Bismuth Triflate Catalyzed Allylation Of Acetals: A Simple And Mild Method For Synthesis Of Homoallyl Ethers, Ram S. Mohan, Laura C. Wieland, Herbert M. Zerth Dec 2001

Bismuth Triflate Catalyzed Allylation Of Acetals: A Simple And Mild Method For Synthesis Of Homoallyl Ethers, Ram S. Mohan, Laura C. Wieland, Herbert M. Zerth

Ram S. Mohan

The allylation of acetals using allyltrimethylsilane is efficiently catalyzed by bismuth triflate (1.0 mol%). The reaction proceeds smoothly at room temperature to afford the corresponding homoallyl ether in good yield. The mild reaction conditions, the low toxicity of bismuth salts, and the high catalytic efficiency of the system make this procedure particularly attractive for large-scale synthesis.


Applications Of Bismuth(Iii) Compounds In Organic Synthesis, Ram S. Mohan, Nicholas M. Leonard, Laura C. Wieland Dec 2001

Applications Of Bismuth(Iii) Compounds In Organic Synthesis, Ram S. Mohan, Nicholas M. Leonard, Laura C. Wieland

Ram S. Mohan

No abstract provided.


Targets, Timetables And Effective Implementing Mechanisms: Necessary Building Blocks For Sustainable Development, John C. Dernbach Dec 2001

Targets, Timetables And Effective Implementing Mechanisms: Necessary Building Blocks For Sustainable Development, John C. Dernbach

John C. Dernbach

No abstract provided.


An Experimental Study Of Grain Scale Melt Segregation Mechanisms In Two Common Crustal Rock Types, Caleb W. Holyoke Iii, Tracy Rushmer Dec 2001

An Experimental Study Of Grain Scale Melt Segregation Mechanisms In Two Common Crustal Rock Types, Caleb W. Holyoke Iii, Tracy Rushmer

Caleb Holyoke

No abstract provided.


Forecasting Volatility In European Stock Markets With Non-Linear Garch Models, Giancarlo Forte, Matteo Manera Dec 2001

Forecasting Volatility In European Stock Markets With Non-Linear Garch Models, Giancarlo Forte, Matteo Manera

Matteo Manera

This paper investigates the forecasting performance of three popular variants of the nonlinear GARCH models, namely VS-GARCH, GJR-GARCH and Q-GARCH, with the symmetric GARCH(1,1) model as a benchmark. The application involves ten European stock price indexes. Forecasts produced by each non-linear GARCH model and each index are evaluated using a common set of classical criteria, as well as forecast combination techniques with constant and non-constant weights. With respect to the standard GARCH specification, the non-linear models generally lead to better forecasts in terms of both smaller forecast errors and lower biases. In-sample forecast combination regressions are better than those from …


Sustainable Development: Now More Than Ever, John C. Dernbach Dec 2001

Sustainable Development: Now More Than Ever, John C. Dernbach

John C. Dernbach

This Article explains how and why sustainable development emerged as a conceptual framework, the basic concepts or principles on which this framework is based, why sustainability is primarily a matter for domestic national governance, and why the United States needs to play a leading role in fostering sustainable development. Because "sustainable" modifies "development," it is first important to understand what development means. Since the end of World War II, development has included at least four related elements: peace and security, economic development, social development, and supportive national governance. Each element is reflected in major multilateral treaties that provide a common …


Synthesis And Physico-Chemical Investigations On 16 And 18 Membered [N4] Macrocycles Modified With Appropriate Carbonyl Functions - A Closer Mimic To A Synthetic Cyclic Tetrapeptide; Isolation Of Stable Encapsulated Derivatives With Zn(Ii),Cd(Ii) And Hg(Ii) Ions, Z. A. Siddiqi, V. J. Mathew, Mohammad Mansoob Khan Dr Dec 2001

Synthesis And Physico-Chemical Investigations On 16 And 18 Membered [N4] Macrocycles Modified With Appropriate Carbonyl Functions - A Closer Mimic To A Synthetic Cyclic Tetrapeptide; Isolation Of Stable Encapsulated Derivatives With Zn(Ii),Cd(Ii) And Hg(Ii) Ions, Z. A. Siddiqi, V. J. Mathew, Mohammad Mansoob Khan Dr

Dr. Mohammad Mansoob Khan

Reaction of 1, 2-diamine or 1,3-diamine with succinic/ phthalic anhydride in 1:1 molar ratio at RT in dioxane results in 16-membered or 18 membered macrocycle which posseses tetraamide/ tetrapeptide functions in the molecular unit which however, exhibit ample reactivity towards metallic substrates affording stable compounds with [MLX2 ] (M=Zn,Cd or Hg; X = CI, SCN or CI04 ) stoichiometry as evidenced from the physico-chemical investigations which confirm that the macrocyclic moieties (L| - L6 ) have the appropriate cavity sizes to encapsulate Zn(II), Cd (II) or Hg(II) ions via coordination through nitrogens of the amide/ peptide functions in tetradentate fashion …


Candidate Set Strategies For Ant Colony Optimisation, Marcus Randall, James Montgomery Dec 2001

Candidate Set Strategies For Ant Colony Optimisation, Marcus Randall, James Montgomery

Marcus Randall

Ant Colony Optimisation based solvers systematically scan the set of possible solution elements before choosing a particular one. Hence, the computational time required for each step of the algorithm can be large. One way to overcome this is to limit the number of element choices to a sensible subset, or candidate set. This paper describes some novel generic candidate set strategies and tests these on the travelling salesman and car sequencing problems. The results show that the use of candidate sets helps to find competitive solutions to the test problems in a relatively short amount of time.


Thin Polyimide Films Prepared By Ionic Self-Assembly, Mark Anderson, Richey Davis, C. Douglas Taylor, Michiaiah Parker, Spencer Clark, Daniela Marciu, Michael Miller Dec 2001

Thin Polyimide Films Prepared By Ionic Self-Assembly, Mark Anderson, Richey Davis, C. Douglas Taylor, Michiaiah Parker, Spencer Clark, Daniela Marciu, Michael Miller

Mark R. Anderson

Layer-by-layer electrostatic deposition of polyelectrolytes was used to modify a gold substrate with polydiallyl dimethylammonium chloride and an Ultem-type poly(amic acid) salt. Following deposition, heat treatment converted the poly(amic acid) salt into a polyimide. A decrease in the thin film thickness and a substantial increase in the interfacial contact angle accompanied thermal treatment. Results from cyclic voltammetry measurements also show that the imidized surface had a decreased dielectric constant relative to an unmodified or a poly(amic acid)-modified interface. Each of these results is consistent with formation of the polyimide. Infrared spectra of the thin films formed by the electrostatic deposition …


Uwit: Underwater Image Toolbox And Mosaicking In Matlab, R. Eustice, O. Pizarro, C. Roman, H. Singh Nov 2001

Uwit: Underwater Image Toolbox And Mosaicking In Matlab, R. Eustice, O. Pizarro, C. Roman, H. Singh

Christopher N. Roman

No abstract provided.


A Short Summary Of Seabed And Some Data Highlights, H. Singh, R. Eustice, C. Roman, O. Pizarro, N. Mcphee Nov 2001

A Short Summary Of Seabed And Some Data Highlights, H. Singh, R. Eustice, C. Roman, O. Pizarro, N. Mcphee

Christopher N. Roman

No abstract provided.


Aging And The Public Health Impact Of Dementia, Ron Brookmeyer, Claudia Kawas Nov 2001

Aging And The Public Health Impact Of Dementia, Ron Brookmeyer, Claudia Kawas

Ron Brookmeyer

No abstract provided.


Finiteness Notions In Fuzzy Sets, Lawrence Stout Nov 2001

Finiteness Notions In Fuzzy Sets, Lawrence Stout

Lawrence N. Stout

Finite sets are one of the most fundamental mathematical structures. In the absence of the axiom of choice there are many different inequivalent definitions of finite even in classical logic. When we allow incomplete existence as in fuzzy sets the situation gets even more complicated. This paper gives nine distinct definitions of finite in a fuzzy context together with examples showing how the properties of the underlying lattice of truth values impact the meanings of finite.


Estimation Of Error In Large Area Underwater Photomosaics Using Vehicle Navigation Data, C. Roman, H. Singh Oct 2001

Estimation Of Error In Large Area Underwater Photomosaics Using Vehicle Navigation Data, C. Roman, H. Singh

Christopher N. Roman

Creating geometrically accurate photomosaics of underwater sites using images collected from an AUV or ROV is a difficult task due to dimensional errors which grow as a function of 3D image distortion and the mosaicking process. Although photomosiacs are accurate locally their utility for accurately representing a large survey area is jeopardized by this error growth. Evaluating the error in a mosaic is the first step in creating globally accurate photomosaics of an unstructured environment with bounded error. Using vehicle navigation data and sensor offsets it is possible to estimate the error present in large area photomosaics independent of the …


Packaging Predictable Assembly With Prediction-Enabled Component Technology, Scott A. Hissam, Gabriel A. Moreno, Judith Stafford, Kurt C. Wallnau Oct 2001

Packaging Predictable Assembly With Prediction-Enabled Component Technology, Scott A. Hissam, Gabriel A. Moreno, Judith Stafford, Kurt C. Wallnau

Gabriel A. Moreno

This report describes the use of prediction-enabled component technology (PECT) as a means of packaging predictable assembly as a deployable product. A PECT results from integrating a component technology with one or more analysis technologies. Analysis technologies allow analysis and prediction of assembly-level properties prior to component assembly, and, presumably, prior to component acquisition. Analysis technologies also identify required component properties and their certifiable descriptions. This report describes the major structures of a PECT. It then discusses the means of validating the predictive powers of a PECT so that consumers may obtain measurably bounded trust in design-time predictions. Last, it …


Dopamine Adsorption At Surface Modified Carbon-Fiber Electrodes, Bradley Bath, Heidi Martin, R. Mark Wightman, Mark Anderson Oct 2001

Dopamine Adsorption At Surface Modified Carbon-Fiber Electrodes, Bradley Bath, Heidi Martin, R. Mark Wightman, Mark Anderson

Mark R. Anderson

Fast-scan cyclic voltammetry at high repetition rates was used to characterize adsorptive properties of dopamine (DA) at native and modified carbon-fiber microelectrode surfaces. Disk electrodes were fabricated from Thornel P55 fibers, and cylindrical electrodes, from Thornel T650 fibers. Their surfaces were modified by physisorption of 2,6-anthraquinone disulfonic acid (2,6-AQDS) or chemisorption of 4-carboxyphenyl or catechols. Chemisorption was accomplished via electrochemical reduction of diazonium salts. The degree of DA adsorption and its oxidation kinetics were found to vary for the two types of native carbon fiber electrodes and with the different chemical overlayers on the carbon surfaces. 2,6-AQDS measurably increased DA …


The Evidence Of The Mode Selectivity Of The Infrared Predissociation Reaction Of The Hydrogen Bonds In The Aniline–Water–Pyrrole Cluster Cation, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito Oct 2001

The Evidence Of The Mode Selectivity Of The Infrared Predissociation Reaction Of The Hydrogen Bonds In The Aniline–Water–Pyrrole Cluster Cation, Taisuke Nakanaga, Naveed Piracha, Fumiyuki Ito

Naveed K. Piracha

The infrared spectrum of aniline–water–pyrrole cluster cation has been measured in the 3 μm region. Four strong vibrational bands were observed at 3313, 3515, 3637, and 3721cm−1, and the cluster dissociated into fragments in two reaction paths, AWP+→AW++P and AWP+→AP++W (A: aniline, W: water, P: pyrrole) when it absorbed an infrared photon. The branching ratio (AW+/AP+) has been determined to be 0.20±0.02 for the NH stretching vibration of aniline (3313cm−1, hydrogen-bonded to pyrrole) and 0.14±0.03 for the other three bands. This vibrational mode dependence should be due to the fast energy transfer from the NH to the intermolecular vibration through …


Teaching Analytical Chemistry To The Masses: How We Went From 2 Courses To 7 Courses In 10 Years, Gary Long, Mark Anderson, Brian Tissue, John Morris Oct 2001

Teaching Analytical Chemistry To The Masses: How We Went From 2 Courses To 7 Courses In 10 Years, Gary Long, Mark Anderson, Brian Tissue, John Morris

Mark R. Anderson

No abstract is currently available.


Interactive Multimedia Over The Internet For Teaching Analytical Chemistry, Mark Anderson Oct 2001

Interactive Multimedia Over The Internet For Teaching Analytical Chemistry, Mark Anderson

Mark R. Anderson

No abstract is currently available.


A Differential Equation Model Of North American Cinematic Box-Office Dynamics, David A. Edwards, Ron Buckmire Oct 2001

A Differential Equation Model Of North American Cinematic Box-Office Dynamics, David A. Edwards, Ron Buckmire

Ron Buckmire

No abstract provided.


Thermodynamic Model For The Prediction Of Ionic Surfactant Influenced Oil Droplet Contact Angles, Samuel Morton, D. Keffer, R. Counce, D. Depaoli, M. Hu Sep 2001

Thermodynamic Model For The Prediction Of Ionic Surfactant Influenced Oil Droplet Contact Angles, Samuel Morton, D. Keffer, R. Counce, D. Depaoli, M. Hu

Samuel A Morton

No abstract provided.


Formalization Of Computer Supported Cooperative Work Applications, Carl Chang, Jia Zhang, Tsang Ming Jiang Sep 2001

Formalization Of Computer Supported Cooperative Work Applications, Carl Chang, Jia Zhang, Tsang Ming Jiang

Jia Zhang

No abstract provided.


Applicability Of General Scenarios To The Architecture Tradeoff Analysis Method, Len Bass, Mark H. Klein, Gabriel A. Moreno Sep 2001

Applicability Of General Scenarios To The Architecture Tradeoff Analysis Method, Len Bass, Mark H. Klein, Gabriel A. Moreno

Gabriel A. Moreno

The SEI has been developing a list of scenarios to characterize quality attributes. The SEI has also been conducting Architecture Tradeoff Analysis Method (ATAM) evaluations. One output of an ATAM evaluation is a collection of scenarios that relate to quality attribute requirements for the specific system being evaluated. In this report, we compare the scenarios elicited from five ATAM evaluations with the scenarios used to characterize the quality attributes. This effort was designed to validate the coverage of the existing set of general scenarios and to analyze trends in the risks uncovered in ATAM reports.


Spectral Energy Distribution Signatures Of Jovian Planets Around White Dwarf Stars., R. Ignace Sep 2001

Spectral Energy Distribution Signatures Of Jovian Planets Around White Dwarf Stars., R. Ignace

Richard Ignace

The problem of detecting Jovian-sized planets orbiting white dwarf stars is considered. Significant IR excesses result from warm Jupiters orbiting a white dwarf of Teff = 10,000 K at a distance of ~103 white dwarf radii (corresponding to ~102 Jupiter radii or a few tenths of an AU) with an orbital period of ~100 days. Such a planet will have a 10 µm flux density at its Wien peak that is comparable to the emission of the white dwarf at that wavelength. Although the white dwarf is much hotter than the planet, the planet will have peak …


Oral History Interview With Mark P. Mccahill, Philip L. Frana Sep 2001

Oral History Interview With Mark P. Mccahill, Philip L. Frana

Philip L Frana

In this oral history Mark P. McCahill, Assistant Director of Academic and Distributed Computing Services at the University of Minnesota, recounts his role as leader of the team that created the popular client/server software for organizing and sharing information on the Internet. McCahill also describes his work in the development of Pop Mail, Gopher VR, Forms Nirvana, the Electronic Grants Management System, and the University of Minnesota Portal.


Line Forces In Keplerian Circumstellar Disks And Precession Of Nearly Circular Orbits., K. G. Gayley, R. Ignace, S. P. Owocki Sep 2001

Line Forces In Keplerian Circumstellar Disks And Precession Of Nearly Circular Orbits., K. G. Gayley, R. Ignace, S. P. Owocki

Richard Ignace

We examine the effects of optically thick line forces on orbiting circumstellar disks, such as occur around Be stars. For radially streaming radiation, line forces are only effective if there is a strong radial velocity gradient, as occurs, for example, in a line-driven stellar wind. However, within an orbiting disk, the radial shear of the azimuthal velocity leads to strong line-of-sight velocity velocity gradients along nonradial directions. As such, in the proximity of a stellar surface extending over a substantial cone angle, the nonradial stellar radiation can impart a significant line force, even in the case of purely circular orbits. …


Terminal Speeds And Ion Fractions From [Caiv] 3.207 Μm In Three Single Wn Stars., Richard Ignace Sep 2001

Terminal Speeds And Ion Fractions From [Caiv] 3.207 Μm In Three Single Wn Stars., Richard Ignace

Richard Ignace

We report on the forbidden emission lines of [CaIV] at 3.207 μm and [NeIII] at 15.56 μm based on Infrared Space Observatory observations. The data set consists of three single Wolf-Rayet stars (WR 1, WR 134, and WR 136) and three binary systems (WR 11, WR 146, and WR 147). For the single stars, only the [CaIV] line was observed. Our primary objectives are to determine the wind terminal speed from the emission-line widths, derive ion number fractions, and discuss the relation between emission profile shapes and wind flow geometry. Compared to previous determinations of the terminal speed, we find …


Transport Properties Of Bi2−Xinxse3 Single Crystals., J. Navrátil, T. Plecháček, J. Horák, S. Karamazov, P. LošŤÁK, Jeffrey Dyck, W. Chen, C. Uher Aug 2001

Transport Properties Of Bi2−Xinxse3 Single Crystals., J. Navrátil, T. Plecháček, J. Horák, S. Karamazov, P. LošŤÁK, Jeffrey Dyck, W. Chen, C. Uher

Jeffrey Dyck

The paper reports on the temperature dependence of the electrical and thermal conductivity, Hall constant, and Seebeck coefficient of Bi2−xInxSe3 (x=0, 0.2, 0.4) single crystals measured over the temperature range from 2 to 300 K. One single-valley conduction band model is used to interpret relations among transport coefficients. The data analysis relies on the use of a mixed carrier scattering mechanism consisting of acoustic scattering and scattering on ionized impurities. The effect of In incorporation into the Bi2Se3 crystal lattice on the individual components of thermal conductivity is evaluated and discussed. Copyright 2001 Academic Press.