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Articles 15751 - 15780 of 16838

Full-Text Articles in Physical Sciences and Mathematics

Pursuing Sustainable Communities: Looking Back, Looking Forward, John C. Dernbach, Scott Bernstein Dec 2002

Pursuing Sustainable Communities: Looking Back, Looking Forward, John C. Dernbach, Scott Bernstein

John C. Dernbach

No abstract provided.


Brain Imaging Of Tongue-Twister Sentence Comprehension: Twisting The Tongue And The Brain, Timothy A. Keller, Patricia A. Carpenter, Marcel Adam Just Dec 2002

Brain Imaging Of Tongue-Twister Sentence Comprehension: Twisting The Tongue And The Brain, Timothy A. Keller, Patricia A. Carpenter, Marcel Adam Just

Marcel Adam Just

No abstract provided.


Novel Examples Of Achiral Bent-Core Azo Compounds Exhibiting B1 And Anticlinic-Antiferroelectric B2 Mesophases, Veena Prasad, Shin-Woong Kang, Satyendra Kumar Dec 2002

Novel Examples Of Achiral Bent-Core Azo Compounds Exhibiting B1 And Anticlinic-Antiferroelectric B2 Mesophases, Veena Prasad, Shin-Woong Kang, Satyendra Kumar

Satyendra Kumar

The first examples of achiral bent-core molecules consisting of an azo linkage and five aromatic rings exhibiting bent-core mesophases are reported. They exhibit B1 and B2 phases as identified by optical microscopy, differential scanning calorimetry, X-ray diffraction, and electro-optical techniques. The B2 phase of these materials is identified to be the anticlinic–antiferroelectric, SmCAPA phase. The mesophases of these compounds have relatively low transition temperatures and wide temperature ranges. The observation of bent-core phases in azo compounds assumes significance from the fact that the introduction of the –NN– linkage adds a new dimension, namely photochromism, to this field.


Bismuth Compounds In Organic Synthesis. Synthesis Of Resorcinarenes Using Bismuth Triflate, Ram S. Mohan, Katherine E. Peterson, Russell C. Smith Dec 2002

Bismuth Compounds In Organic Synthesis. Synthesis Of Resorcinarenes Using Bismuth Triflate, Ram S. Mohan, Katherine E. Peterson, Russell C. Smith

Ram S. Mohan

Bismuth triflate (5 mol%) smoothly catalyzes the condensation of aromatic and aliphatic aldehydes with resorcinol to give tetrameric cyclic products, resorcinarenes. With benzaldehyde, the product is obtained as a mixture of two diastereomers and the ratio of the diastereomers depends on reaction time. On the other hand, a single diastereomer is obtained with aliphatic aldehydes. The low toxicity and ease of handling of bismuth compounds coupled with fast reaction times make this method an attractive alternative to the existing methods for resorcinarene formation


Bismuth Compounds In Organic Synthesis. Deprotection Of Ketoximes Using Bismuth Bromide-Bismuth Triflate, Ram S. Mohan, Joshua N. Arnold, Patrick D. Hayes, Robert L. Kohaus Dec 2002

Bismuth Compounds In Organic Synthesis. Deprotection Of Ketoximes Using Bismuth Bromide-Bismuth Triflate, Ram S. Mohan, Joshua N. Arnold, Patrick D. Hayes, Robert L. Kohaus

Ram S. Mohan

Ketoximes undergo deprotection in CH3CN/acetone/H2O (3:6:1) in the presence of 20–40 mol% BiBr3/5 mol% Bi(OTf)3. Bismuth(III) salts are relatively non-toxic, insensitive to air and inexpensive. These features coupled with the use of a relatively non-toxic solvent system make this method an attractive alternative to existing routes for deprotection of ketoximes.


Open Problems From The Linz2000 Closing Session, Lawrence N. Stout Dec 2002

Open Problems From The Linz2000 Closing Session, Lawrence N. Stout

Lawrence N. Stout

No abstract provided.


Strukturationen Der Interaktivität, Rudolf Kaehr Dec 2002

Strukturationen Der Interaktivität, Rudolf Kaehr

Rudolf Kaehr

No abstract provided.


Long-Run Models Of Oil Stock Prices, Alessandro Lanza, Matteo Manera, Massimo Giovannini, Margherita Grasso Dec 2002

Long-Run Models Of Oil Stock Prices, Alessandro Lanza, Matteo Manera, Massimo Giovannini, Margherita Grasso

Matteo Manera

The identification of the forces that drive oil stock prices is extremely important given the size of the Oil&Gas industry and its links with the energy sector and the environment. In the next decade oil companies will have to deal with international policies to contrast climate change. This issue is likely to affect companies’ shareholder values. In this paper we focus on the long-run financial determinants of the stock prices of six major oil companies (Bp, Chevron-Texaco, Eni, Exxon-Mobil, Royal Dutch Shell, Total-Fina-Elf) using multivariate cointegration techniques and vector error correction models. Weekly oil stock prices are analyzed together with …


Achieving Sustainable Development: The Centrality And Multiple Facets Of Integrated Decisionmaking, John C. Dernbach Dec 2002

Achieving Sustainable Development: The Centrality And Multiple Facets Of Integrated Decisionmaking, John C. Dernbach

John C. Dernbach

No abstract provided.


Connection Between Adam-Gibbs Theory And Spatially Heterogeneous Dynamics, N. Giovambattista, S. V. Buldyrev, Francis W. Starr, H. E. Stanley Dec 2002

Connection Between Adam-Gibbs Theory And Spatially Heterogeneous Dynamics, N. Giovambattista, S. V. Buldyrev, Francis W. Starr, H. E. Stanley

Francis Starr

No abstract provided.


Linear Perturbations Of A Nonoscillatory Second Order Differential Equation Ii, William F. Trench Dec 2002

Linear Perturbations Of A Nonoscillatory Second Order Differential Equation Ii, William F. Trench

William F. Trench

No abstract provided.


Text Alignment With Handwritten Documents, E. Micah Kornfield, R. Manmatha, James Allan Dec 2002

Text Alignment With Handwritten Documents, E. Micah Kornfield, R. Manmatha, James Allan

R. Manmatha

Todays digital libraries increasingly include not only printed text but also scanned handwritten pages and other multimedia material. There are, however, few tools available for manipulating handwritten pages. Here, we propose an algorithm based on dynamic time warping (DTW) for a word by word alignment ofhandwritten documents with their (ASCII) transcripts. We see at least three uses for such alignment al gorithms. First, alignment algorithms allow us to produce displays (for example on the web) which allow a person to easily find their place in the manuscript when reading a transcript. Second, such alignment algorithms will allow us to produce …


Community Environmental Policing, Gregg P. Macey Dec 2002

Community Environmental Policing, Gregg P. Macey

Gregg P. Macey

This paper evaluates a new form of public participation in environmental monitoring and regulation advanced through local bucket brigades, which allow community members to sample air emissions near industrial facilities. These brigades represent a new form of community environmental policing, in which residents participate in collecting, analyzing, and deploying environmental information, and more importantly, in an array of public policy dialogues. Use of this sampling technology has had marked effects on local residents' perceptions and participation in emergency response and citizens' right-to-know. However, when viewed through the lens of the more developed literature on community policing, the bucket brigades are …


Uniform Convergence Of Cesàro Means Of Negative Order Of Double Walsh-Fourier Series, Ushangi Goginava Dec 2002

Uniform Convergence Of Cesàro Means Of Negative Order Of Double Walsh-Fourier Series, Ushangi Goginava

Ushangi Goginava

No abstract provided.


Challenges In Information Retrieval And Language Modeling, Jay Aslam, Nichols Belkin, Chris Buckley, Jamie Callan, Sue Dumais, Norbert Fuhr, Donna Harman, David J. Harper, Djoerd Hiemstra, Thomas Hofmann, Eduard Hovy, Wessel Kraaij, John Lafferty, Victor Lavrenko, David Lewis, Liz Liddy, R. Manmatha, Andrew Mccallum, Jay Ponte, John Prager, Dragomir Radev, Philip Resnik, Stephen Robertson, Roni Rosenfeld, Salim Roukos, Mark Sanderson, Rich Schwartz, Amit Singhal, Alan Smeaton, Howard Turtle, Ellen Voorhees, Ralph Weischedel, Jinxi Xu, Chengxiang Zhai Dec 2002

Challenges In Information Retrieval And Language Modeling, Jay Aslam, Nichols Belkin, Chris Buckley, Jamie Callan, Sue Dumais, Norbert Fuhr, Donna Harman, David J. Harper, Djoerd Hiemstra, Thomas Hofmann, Eduard Hovy, Wessel Kraaij, John Lafferty, Victor Lavrenko, David Lewis, Liz Liddy, R. Manmatha, Andrew Mccallum, Jay Ponte, John Prager, Dragomir Radev, Philip Resnik, Stephen Robertson, Roni Rosenfeld, Salim Roukos, Mark Sanderson, Rich Schwartz, Amit Singhal, Alan Smeaton, Howard Turtle, Ellen Voorhees, Ralph Weischedel, Jinxi Xu, Chengxiang Zhai

R. Manmatha

Information retrieval (IR) research has reached a point where it is appropriate to assess progress and to define a research agenda for the next five to ten years. This report summarizes a discussion of IR research challenges that took place at a recent workshop.

The attendees of the workshop considered information retrieval research in a range of areas chosen to give broad coverage of topic areas that engage information retrieval researchers. Those areas are retrieval models, cross-lingual retrieval, Web search, user modeling, filtering, topic detection and tracking, classification, summarization, question answering, metasearch, distributed retrieval, multimedia retrieval, information extraction, as well …


Debating E-Commerce: Engaging Students In Current Events, Amber Settle, André Berthiaume Dec 2002

Debating E-Commerce: Engaging Students In Current Events, Amber Settle, André Berthiaume

Amber Settle

A fundamental task for information technology educators is to help students understand the basic ethical, social, and legal issues inherent in the discipline. We present a method for achieving this goal using in-class debates. Debates allow for a high-level of participation, demand that students conduct significant research, and provide an interactive environment. This encourages the development of communication skills and exposes students to alternative points of view. The debates were conducted in two courses that provide a survey of some aspect of e-commerce technology, one at the undergraduate level and the other at the Masters level.


Differential Effects Of Syntactic And Semantic Processing On The Subregions Of Broca's Area, Sharlene D. Newman, Marcel Adam Just, Timothy A. Keller, Jennifer Roth, Patricia A. Carpenter Dec 2002

Differential Effects Of Syntactic And Semantic Processing On The Subregions Of Broca's Area, Sharlene D. Newman, Marcel Adam Just, Timothy A. Keller, Jennifer Roth, Patricia A. Carpenter

Marcel Adam Just

No abstract provided.


Reactions Of Boranes And Metallaboranes With Phosphines, Lawrence Barton, Oleg Volkov, Mitsuhiro Hata, Paul Mcquade, Nigam P. Rath Dec 2002

Reactions Of Boranes And Metallaboranes With Phosphines, Lawrence Barton, Oleg Volkov, Mitsuhiro Hata, Paul Mcquade, Nigam P. Rath

Nigam Rath

This paper reports extensions of the well-established field of phosphine–borane chemistry. Linked clusters, for example, {[(PPh3)2(CO)OsB4H7-3-BH2-PPh2]2 [(Fe(C5H4)2]}, are formed in reactions of rigid backboned bidentate phosphines with {2,2,2-(PPh3)2(CO)-nido-2-OsB5H9]. Reaction of bidentate phosphines with the unsaturated clusters [8,8-PPh3)2-nido-8,7-RhSB9H10] and [9,9-(PPh3)2-nido-9,7,8-RhC2B8 H11] leads to the isolation of novel species such as {1-(PPh3)[1,3-(µ-dppm)]-closo -1,2-RhSB9H8},with a dppm molecule bridging adjacent metal and boron vertices in the cage, [1,1-(ç2-dppe)-3-(ç1-dppm)-closo-1,2-RhSB 9H8], a mixed ligand system, and {9,9-ç2-[(ç2-BH3)PPh2PCH2 PPh2]-nido- 9,7,8-RhC2B8H11} which contains a bidentate dppm BH3 moiety. The formation of bidentate phosphine-linked main group transition-metal moieties such as [BH3PPh2(CH)nPPh2IrCp*Cl2] is also described as is an example of …


A Soap-Oriented Component-Based Framework Supporting Device-Independent Multimedia Web Services, Jia Zhang, Jen-Yao Chung Nov 2002

A Soap-Oriented Component-Based Framework Supporting Device-Independent Multimedia Web Services, Jia Zhang, Jen-Yao Chung

Jia Zhang

No abstract provided.


Quantitative Evaluation Of Hiv Preventon Programs, Edward Kaplan, Ron Brookmeyer Nov 2002

Quantitative Evaluation Of Hiv Preventon Programs, Edward Kaplan, Ron Brookmeyer

Ron Brookmeyer

How successful are HIV prevention programs? Which HIV prevention programs are most cost effective? Which programs are worth expanding and which should be abandoned altogether? This book addresses the quantitative evaluation of HIV prevention programs, assessing for the first time several different quantitative methods of evaluation


Prevention Of Inhalational Anthrax In The U.S. Outbreak, Ron Brookmeyer, Natalie Blades Nov 2002

Prevention Of Inhalational Anthrax In The U.S. Outbreak, Ron Brookmeyer, Natalie Blades

Ron Brookmeyer

No abstract provided.


Applications Of Underground Structures For The Protection Of Critical Infrastructure, George H. Baker, Richard G. Little, Don A. Linger Nov 2002

Applications Of Underground Structures For The Protection Of Critical Infrastructure, George H. Baker, Richard G. Little, Don A. Linger

George H Baker

The U.S. President’s Commission on Critical Infrastructure Protection (PCCIP), convened in the wake of the bombing of the Murrah Federal Building in Oklahoma City, concluded that the nation’s physical security and economic security depend on our critical energy, communications, and computer infrastructures. While a primary motivating event for the establishment of the commission was the catastrophic physical attack of the Murrah Building, it is ironic that the commission focused its attention primarily on cyber threats. Their rationale was that cyber vulnerabilities posed a new, unaddressed challenge to infrastructure security. This approach was further questioned by the events of September 11, …


Supervisory Control And Data Acquisition (Scada) Systems, George H. Baker, Allan Berg Nov 2002

Supervisory Control And Data Acquisition (Scada) Systems, George H. Baker, Allan Berg

George H Baker

Our critical national infrastructure systems have become almost universally dependent upon computer-based control systems technically referred to as supervisory control and data acquisition (SCADA) systems. SCADA systems evolved from the telemetry and event-alarm systems developed in the early days of utilities. With the widespread use of SCADA systems, computers have become the "basis element" for much of our critical infrastructure. Thus, the disruption of controlling computer terminals and networks due to natural disasters, electric power failure, accidents or malicious activity can have catastrophic consequences.


A Convenient One-Pot, Organoaluminum Mediated Vinylsilane Synthesis From Non-Enolizable Ketones Via The Peterson Protocol, Man Lung Kwan, Merle Battiste Nov 2002

A Convenient One-Pot, Organoaluminum Mediated Vinylsilane Synthesis From Non-Enolizable Ketones Via The Peterson Protocol, Man Lung Kwan, Merle Battiste

Man Lung Desmond Kwan

Vinylsilanes serve as convenient vinyl anion equivalents which have gained popularity over decades. A variety of non-enolizable aromatic ketones are converted to the corresponding vinylsilanes in a one-pot procedure involving the addition of (trimethylsilylmethyl)lithium to aromatic ketones followed by addition of diethylaluminum chloride and then small amounts of water. Halide and alkoxide substituents are tolerated, and this trans-stereoselective (broad generalization; the most sterically bulky group on the double bond is trans to the trimethylsilyl group) reaction affords vinylsilanes in good yield.


Oral History Interview With Laszlo A. Belady, Philip L. Frana Nov 2002

Oral History Interview With Laszlo A. Belady, Philip L. Frana

Philip L Frana

Belady discusses his early life and education in Hungary, escape to West Germany during the 1956 revolution, and work as a draftsman at Ford Motor Company in Cologne and as an aerodynamics engineer at Dassault in Paris. Belady covers his 1961 immigration into the United States, where he joined International Business Machines and did early work in operating systems, virtual machine architectures, program behavior modeling, memory management, computer graphics, Asian character sets, and data security. He also ...


Structure, Wettability, And Reductive Desorption Of Self-Assembled Monolayers Of Positional Isomers Of (12-Mercaptododecyl)Phenol, Francisco Cavadas, Mark Anderson Nov 2002

Structure, Wettability, And Reductive Desorption Of Self-Assembled Monolayers Of Positional Isomers Of (12-Mercaptododecyl)Phenol, Francisco Cavadas, Mark Anderson

Mark R. Anderson

No abstract is currently available.


Asymptotic Solitons For A Higher-Order Modified Korteweg–De Vries Equation, T. Marchant Oct 2002

Asymptotic Solitons For A Higher-Order Modified Korteweg–De Vries Equation, T. Marchant

Tim Marchant

Solitary wave interaction for a higher-order modified Korteweg–de Vries (mKdV) equation is examined. The higher-order mKdV equation can be asymptotically transformed to the mKdV equation, if the higher-order coefficients satisfy a certain algebraic relationship. The transformation is used to derive the higher-order two-soliton solution and it is shown that the interaction is asymptotically elastic. Moreover, the higher-order phase shifts are derived using the asymptotic theory. Numerical simulations of the interaction of two higher-order solitary waves are also performed. Two examples are considered, one satisfies the algebraic relationship derived from the asymptotic theory, and the other does not. For the example …


Molecular Dynamics Simulations Of Sodium Dodecyl Sulfate Micelle In Water: The Behavior Of Water, Chrystal Bruce, Sanjib Senapati, Max Berkowitz, L. Perera, M. Forbes Oct 2002

Molecular Dynamics Simulations Of Sodium Dodecyl Sulfate Micelle In Water: The Behavior Of Water, Chrystal Bruce, Sanjib Senapati, Max Berkowitz, L. Perera, M. Forbes

Chrystal D. Bruce

Using a 5 ns explicit atom molecular dynamics simulation of a 60 monomer sodium dodecyl sulfate micellar system containing 7579 TIP3P water molecules, the behavior of water in different electrostatic environments was examined. Structural evaluation of the system revealed that penetration of water molecules into the micelle was restricted to the headgroup region, leaving a 12 Å water-free hydrocarbon core. Water molecules near the headgroup exhibit a distortion of the water−water hydrogen bonding network due to headgroup oxygen−water hydrogen bond formation. The dynamic implications of this distortion are manifested in the decay of the dipole autocorrelation function, Φ(t) and translational …


Polarization From Microlensing Of Spherical Circumstellar Envelopes By A Point Lens., J. F. L. Simmons, J. E. Bjorkman, R. Ignace, I. J. Coleman Oct 2002

Polarization From Microlensing Of Spherical Circumstellar Envelopes By A Point Lens., J. F. L. Simmons, J. E. Bjorkman, R. Ignace, I. J. Coleman

Richard Ignace

We discuss the flux and polarization signals obtained from the microlensing of stars with extended circumstellar envelopes by a single point-mass lens. A previous paper considered the case of main-sequence stars, and showed that microlensing of the stellar photosphere could produce a small net polarization (up to 0.1 per cent). In this paper, we show that stars with extensive envelopes will show a much higher level of variable polarization (up to 10 per cent), even if they are spherically symmetric. Since the stellar envelopes most likely to be lensed are produced by red giant winds, we also investigate the effects …


Application Of Steaming Video And Flash Animation For Teaching Analytical Chemistry, Mark Anderson Oct 2002

Application Of Steaming Video And Flash Animation For Teaching Analytical Chemistry, Mark Anderson

Mark R. Anderson

No abstract is currently available.