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1999

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Full-Text Articles in Physical Sciences and Mathematics

A Perturbation Of A Periodic Hamiltonian System, Gregory S. Spradlin Nov 1999

A Perturbation Of A Periodic Hamiltonian System, Gregory S. Spradlin

Gregory S. Spradlin

No abstract provided.


Transparent Stacked Organic Light Emitting Devices. I. Design Principles And Transparent Compound Electrodes, G. Gu, G. Parthasarathy, P. E. Burrows, Peifang Tian, I. G. Hill, A. Kahn, S. R. Forrest Oct 1999

Transparent Stacked Organic Light Emitting Devices. I. Design Principles And Transparent Compound Electrodes, G. Gu, G. Parthasarathy, P. E. Burrows, Peifang Tian, I. G. Hill, A. Kahn, S. R. Forrest

Peifang Tian

Vertical stacking of organic light emitting devices (OLEDs) that emit the three primary colors is a means for achieving full-color flat panel displays. The physics, performance, and applications of stacked OLEDs (SOLEDs) are discussed in this and the following paper (Papers I and II, respectively). In Paper I, we analyze optical microcavity effects that can distort the emission colors of SOLEDs if not properly controlled, and describe design principles to minimize these parasitic effects. We also describe the fabrication and operating characteristics of transparent contacts that are an integral part of SOLEDs. We demonstrate that both metal-containing and metal-free transparent …


Transparent Stacked Organic Light Emitting Devices. Ii. Device Performance And Applications To Displays, G. Gu, G. Parthasarathy, Peifang Tian Oct 1999

Transparent Stacked Organic Light Emitting Devices. Ii. Device Performance And Applications To Displays, G. Gu, G. Parthasarathy, Peifang Tian

Peifang Tian

Vertical stacking of organic light emitting devices (OLEDs) that emit the three primary colors is shown to be a means for achieving efficient and bright full-color displays. In Paper I, we addressed stacked OLED (SOLED) design and fabrication principles to optimize emission colors, operating voltage, and efficiency. Here, we present results on two different (metal-containing and metal-free cathode) SOLED structures that exhibit performance suitable for many full-color display applications. The operating voltages at 10 mA/cm2 (corresponding to video display brightnesses) are 6.8, 8.5, and 12.1 V for the red (R), green (G), and blue (B) elements of the metal-containing SOLED, …


Regional Hydrology Of The Dixie Valley Geothermal Field, Nevada: Preliminary Interpretations Of Chemical And Isotopic Data, Gregory Nimz, Cathy Janik, Fraser Goff, Charles Dunlap, Mark Huebner, Dale Counce, Stuart Johnson Sep 1999

Regional Hydrology Of The Dixie Valley Geothermal Field, Nevada: Preliminary Interpretations Of Chemical And Isotopic Data, Gregory Nimz, Cathy Janik, Fraser Goff, Charles Dunlap, Mark Huebner, Dale Counce, Stuart Johnson

Charles Dunlap

Chemical and isotopic analyses of Dixie Valley regional waters indicate several distinct groups ranging in recharge age from Pleistocene (<20 ka) to recent (<50a). Valley groundwater is older than water from perennial springs and artesian wells in adjacent ranges, with Clan Alpine range (east) much younger (most <50a) than Stillwater range (west; most > 1OOOa).Geothermal field fluids (-12-14 ka) appear derived from water similar in composition to non-thermal groundwater observed today in valley artesian wells (also -14 ka). Geothermal fluid interaction with mafic rocks (Humboldt Lopolith) appears to be common, and significant reaction with granodiorite may also occur. Despite widespread occurrence of carbonate rocks, largescale chemical interaction appears minor. Age asymmetry of the ranges, more extensive interaction with deep- seated waters in the west, and distribution of springs and artesian wells suggest the existence …


Precise, Scalable Shadow Mask Patterning Of Vacuum-Deposited Organic Light Emitting Devices, Peifang Tian, V. Bulovic, P. Burrows, G. Gu, S. Forrest, T. Zhou Aug 1999

Precise, Scalable Shadow Mask Patterning Of Vacuum-Deposited Organic Light Emitting Devices, Peifang Tian, V. Bulovic, P. Burrows, G. Gu, S. Forrest, T. Zhou

Peifang Tian

We demonstrate a scheme to pattern vacuum-deposited, small molecular weight organic light emitting diodes 􏰉OLEDs􏰀. Both the organic thin films and the metallic electrodes are patterned by shifting the position of a single shadow mask which accompanies the substrate throughout the deposition process. A full color, stacked OLED 􏰉SOLED􏰀 has been fabricated using this technique. The substrate movement relative to the mask was manually controlled to a root mean square accuracy of 􏰑8 􏰇m using a mask translating fixture. The performance of the patterned SOLED is comparable with that of devices fabricated by conventional, low tolerance methods. The limits to …


Computational Complexity For Continuous Time Dynamics, Hava Siegelmann, Asa Ben-Hur, Shmuel Fishman Aug 1999

Computational Complexity For Continuous Time Dynamics, Hava Siegelmann, Asa Ben-Hur, Shmuel Fishman

Hava Siegelmann

Dissipative flows model a large variety of physical systems. In this Letter the evolution of such systems is interpreted as a process of computation; the attractor of the dynamics represents the output. A framework for an algorithmic analysis of dissipative flows is presented, enabling the comparison of the performance of discrete and continuous time analog computation models. A simple algorithm for finding the maximum of n numbers is analyzed, and shown to be highly efficient. The notion of tractable (polynomial) computation in the Turing model is conjectured to correspond to computation with tractable (analytically solvable) dynamical systems having polynomial complexity.


The Discovery-Oriented Approach To Organic Chemistry. 2. Selectivity In Alcohol Oxidation. An Exercise In 1H Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Steven R. Shadwick Jul 1999

The Discovery-Oriented Approach To Organic Chemistry. 2. Selectivity In Alcohol Oxidation. An Exercise In 1H Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Steven R. Shadwick

Ram S. Mohan

We have developed a simple oxidation experiment that presents the student with a puzzle and is a good exercise in 1H NMR spectroscopy. The experiment, which illustrates the important concept of selectivity in organic synthesis, involves selective oxidation of a mixture of 1-heptanol and 2-heptanol using commercial swimming pool chlorine. 1H NMR analysis of the product mixture allows the student to determine the selectivity exhibited by the reagent.


An Explanation Of Observed Trends In The X-Ray Emission From Single Wolf-Rayet Stars., R. Ignace, L. M. Oskinova Jul 1999

An Explanation Of Observed Trends In The X-Ray Emission From Single Wolf-Rayet Stars., R. Ignace, L. M. Oskinova

Richard Ignace

The O and early B star winds show empirical correlations between X-ray (L_x) and Bolometric (L_Bol) luminosity as well as wind properties such as wind momentum and wind kinetic energy. Wolf-Rayet stars do not. We discuss scaling relations to qualitatively explain this lack of correlation among the WR winds and to quantitatively reproduce the observed ratio of X-ray luminosities between the N-rich WN types and C-rich WC types. If (a) the filling factor of hot X-ray emitting gas varies as (M⊙/v_\infty)(-1) for stars of different mass loss and terminal speed and (b) the ambient Wolf-Rayet wind component is optically thick …


The Hanle Effect As A Diagnostic Of Magnetic Fields In Stellar Envelopes Ii. Some Theoretical Results For Resolved Line Profiles., R. Ignace, J. P. Cassinelli, K. H. Nordsieck Jul 1999

The Hanle Effect As A Diagnostic Of Magnetic Fields In Stellar Envelopes Ii. Some Theoretical Results For Resolved Line Profiles., R. Ignace, J. P. Cassinelli, K. H. Nordsieck

Richard Ignace

A magnetic field diagnostic of stellar winds that uses the Hanle effect is discussed. This diagnostic pertains to the modification of resonance-line-scattering polarization in the presence of magnetic fields. The case for resolved polarized profiles of optically thin emission lines is considered, and some analytic results for an expanding equatorial disk are derived. Numerical results for a dipole magnetic field embedded in a spherical outflow are also presented. Although the considerations are somewhat simplified, the primary conclusion is that the modification or creation of line profile polarization by the Hanle effect can be used to discriminate between different magnetic field …


Scattering Polarization Due To Light Source Anisotropy I. Large Spherical Envelope., M. B. Al-Malki, J. F. L. Simmons, R. Ignace, J. C. Brown, D. Clarke Jun 1999

Scattering Polarization Due To Light Source Anisotropy I. Large Spherical Envelope., M. B. Al-Malki, J. F. L. Simmons, R. Ignace, J. C. Brown, D. Clarke

Richard Ignace

Expressions are developed for the flux and polarization of radiation scattered by a spherically symmetric envelope for a central point stellar light source that radiates anisotropically. These are obtained in terms of the components of the spherical harmonics of the flux anisotropy from the source. Such anisotropy can arise from stellar spots, or from distortion of the star through rotation, pulsation, or magnetic effects. Explicit expressions for the Stokes parameters are obtained in the case of an ellipsoidal star of uniform surface brightness. It is thus shown that even when the scattering envelope is spherical, observationally significant polarization can arise …


Probabilistic Crowding: Deterministic Crowding With Probabilistic Replacement, Ole J. Mengshoel, David E. Goldberg Jun 1999

Probabilistic Crowding: Deterministic Crowding With Probabilistic Replacement, Ole J. Mengshoel, David E. Goldberg

Ole J Mengshoel

This paper presents a novel niching algorithm, probabilistic crowding. Like its predecessor deterministic crowding, probabilistic crowding is fast, simple, and requires no parameters beyond that of the classical GA. In probabilistic crowding, subpopulations are maintained reliably, and we analyze and predict how this maintenance takes place.

This paper also identifies probabilistic crowding as a member of a family of algorithms, which we call integrated tournament algorithms. Integrated tournament algorithms also include deterministic crowding, restricted tournament selection, elitist recombination, parallel recombinative simulated annealing, the Metropolis algorithm, and simulated annealing.


Phd Thesis (Doctorat De Spécialité): Université De Ouagadougou, 1999. Dr. Mamoudou H. Dicko. Purification Et Propriétés Physico-Chimiques Des Enzymes De Curculigo Pilosa, Gladiolus Klattianus Et Boscia Senegalensis Catalysant L'Hydrolyse Des Polysaccharides (Amidon Et Béta-Glucanes), Mamoudou H. Dicko Prof. Jun 1999

Phd Thesis (Doctorat De Spécialité): Université De Ouagadougou, 1999. Dr. Mamoudou H. Dicko. Purification Et Propriétés Physico-Chimiques Des Enzymes De Curculigo Pilosa, Gladiolus Klattianus Et Boscia Senegalensis Catalysant L'Hydrolyse Des Polysaccharides (Amidon Et Béta-Glucanes), Mamoudou H. Dicko Prof.

Pr. Mamoudou H. DICKO, PhD

The objective of this study was the research of novel and inexpensive sources of polysaccharides degrading enzymes such as amylases and glucanases from local plants in order to justify their biotechnological applications. The isolation of two l3-amylases and an endo-1,3-ß-D-glucanase was reached using common protein purification methods such as buffer extraction, ammonium sulfate fractionation, ionexchange and gel filtration chromatographies. The methods used were simple and easily reproducible, suggesting the possibilfty of large-scale production. ln the crude extract of Curculigo pilosa tuber, only ß-amylase was detected as starch degrading enzyme and its activity was approximately 282 Uig of fresh material. The …


Reference Materials For Calorimetry And Differential Thermal Analysis, R. Sabbah, An Xu-Wu, J.S. Chickos, M.L.Planas Leitão, M.V. Roux, L.A. Torres May 1999

Reference Materials For Calorimetry And Differential Thermal Analysis, R. Sabbah, An Xu-Wu, J.S. Chickos, M.L.Planas Leitão, M.V. Roux, L.A. Torres

James Chickos

No abstract provided.


Discontinuities In Recurrent Neural Networks, R. Gavaldà, Hava Siegelmann Mar 1999

Discontinuities In Recurrent Neural Networks, R. Gavaldà, Hava Siegelmann

Hava Siegelmann

This article studies the computational power of various discontinuous real computational models that are based on the classical analog recurrent neural network (ARNN). This ARNN consists of finite number of neurons; each neuron computes a polynomial net function and a sigmoid-like continuous activation function. We introduce arithmetic networks as ARNN augmented with a few simple discontinuous (e.g., threshold or zero test) neurons. We argue that even with weights restricted to polynomial time computable reals, arithmetic networks are able to compute arbitrarily complex recursive functions. We identify many types of neural networks that are at least as powerful as arithmetic nets, …


The Discovery-Oriented Approach To Organic Chemistry 1. Nitration Of Unknown Organic Compounds. An Exercise In 1H Nmr And 13C Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Sonia R. Mcelveen, Kostas Gavardinas, Jean A. Stamberger Mar 1999

The Discovery-Oriented Approach To Organic Chemistry 1. Nitration Of Unknown Organic Compounds. An Exercise In 1H Nmr And 13C Nmr Spectroscopy For Sophomore Organic Laboratories, Ram S. Mohan, Sonia R. Mcelveen, Kostas Gavardinas, Jean A. Stamberger

Ram S. Mohan

Nitration is one of the most fundamental reactions in organic chemistry. However, the majority of the nitration experiments found in the standard lab textbooks are of the "cookbook" variety and convey none of the excitement associated with discovery in experimental chemistry. We have developed two simple nitration experiments that present the student with a puzzle and are a good exercise in 1H NMR and 13C NMR spectroscopy. 13 C NMR spectroscopy is a powerful structure elucidation tool and yet not many examples of the use of 13C NMR spectroscopy in organic lab experiments can be found. The experiment involves nitration …


Mil-Std-188-125-2, High-Altitude Emp Protection For Transportable Systems Mar 1999

Mil-Std-188-125-2, High-Altitude Emp Protection For Transportable Systems

George H Baker

This standard establishes minimum requirements and design objectives for high-altitude electromagnetic pulse (HEMP) hardening of transportable1 ground-based systems that perform critical, time-urgent command, control, communications, computer, and intelligence (C4I) missions. Systems required to fully comply with the provisions of the standard will be designated by the Joint Chiefs of Staff, a Military Department Headquarters, or a Major Command.

The standard prescribes minimum performance requirements for low-risk protection from mission-aborting damage or upset due to HEMP threat environments. The standard also addresses minimum testing requirements for demonstrating that prescribed performance has been achieved and for verifying that the installed protection measures …


Graded Functional Activation In The Visuo-Spatial System With The Amount Of Task Demand, Patricia Carpenter, Marcel Just, Timothy Keller, William Eddy, Keith Thulborn Dec 1998

Graded Functional Activation In The Visuo-Spatial System With The Amount Of Task Demand, Patricia Carpenter, Marcel Just, Timothy Keller, William Eddy, Keith Thulborn

Marcel Adam Just

No abstract provided.


Consumption Adjustment Under Time-Varying Income Uncertainty, Douglas Steigerwald, Joon-Ho Hahm Dec 1998

Consumption Adjustment Under Time-Varying Income Uncertainty, Douglas Steigerwald, Joon-Ho Hahm

Douglas G. Steigerwald

We study the effect of income uncertainty on consumption in a model that includes precautionary saving. In contrast to previous studies, we focus on time-series variation in income uncertainty. Our time-series measure of income uncertainty is constructed from a panel of forecasts. We find evidence of precautionary saving in that increases in income uncertainty are related to increases in aggregate rates of saving. We also find evidence that anticipated income growth rates have less explanatory power for consumption growth rates after conditioning on income uncertainty. The evidence indicates the presence of forward-looking consumers who gradually adjust precautionary savings in response …


Alternative Polynomial And Holomorphic Dunford-Pettis Properties, Walden Freedman Dec 1998

Alternative Polynomial And Holomorphic Dunford-Pettis Properties, Walden Freedman

Walden Freedman

Alternatives to the Polynomial Dunford-Pettis property and the Holomorphic Dunford-Pettis property, called the PDP1 and HDP1 properties, respectively, are introduced. These are shown to be equivalent to the DP1 property, an alternative Dunford-Pettis property previously introduced by the author, thus mirroring the equivalence of the three original properties.


Conditional Convergence Of Infinite Products, William F. Trench Dec 1998

Conditional Convergence Of Infinite Products, William F. Trench

William F. Trench

No abstract provided.


Dynamics Of Simulated Water Under Pressure, Francis W. Starr, F. Sciortino, H. E. Stanley Dec 1998

Dynamics Of Simulated Water Under Pressure, Francis W. Starr, F. Sciortino, H. E. Stanley

Francis Starr

No abstract provided.


Time Course Of Fmri-Activation In Language And Spatial Networks During Sentence Comprehension, Patricia A. Carpenter, Marcel Adam Just, Timothy A. Keller, William F. Eddy, Keith R. Thulborn Dec 1998

Time Course Of Fmri-Activation In Language And Spatial Networks During Sentence Comprehension, Patricia A. Carpenter, Marcel Adam Just, Timothy A. Keller, William F. Eddy, Keith R. Thulborn

Marcel Adam Just

No abstract provided.


Linear Asymptotic Equilibrium For Nilpotent Systems Of Difference Equations, William F. Trench Dec 1998

Linear Asymptotic Equilibrium For Nilpotent Systems Of Difference Equations, William F. Trench

William F. Trench

No abstract provided.


Plasticity Of Language-Related Brain Function During Recovery From Strok, Keith R. Thulborn, Patricia A. Carpenter, Marcel Adam Just Dec 1998

Plasticity Of Language-Related Brain Function During Recovery From Strok, Keith R. Thulborn, Patricia A. Carpenter, Marcel Adam Just

Marcel Adam Just

No abstract provided.


Computational Modeling Of High-Level Cognition And Brain Function, Marcel Adam Just, Patricia A. Carpenter, Sashank Varma Dec 1998

Computational Modeling Of High-Level Cognition And Brain Function, Marcel Adam Just, Patricia A. Carpenter, Sashank Varma

Marcel Adam Just

No abstract provided.


Indexing Flower Patent Images Using Domain Knowledge, Madirakshi Das, R. Manmatha, Edward M. Riseman Dec 1998

Indexing Flower Patent Images Using Domain Knowledge, Madirakshi Das, R. Manmatha, Edward M. Riseman

R. Manmatha

A new approach to indexing a specialized database by utilizing the color and spatial domain knowledge available for the database is described. This approach is illustrated by using it to provide a solution to the problem of indexing images of flowers for searching a flower patents database by color. The flower region is isolated from the background by using an automatic iterative segmentation algorithm with domain knowledge-driven feedback. The color of the flower is defined by the color names present in the flower region and their relative proportions. The database can be queried by example and by color names. The …


A Synthesis Of Lead Isotopes In Two Millennia Of European Air, Charles Dunlap, Eiliv Steinnes, A. Russell Flegal Dec 1998

A Synthesis Of Lead Isotopes In Two Millennia Of European Air, Charles Dunlap, Eiliv Steinnes, A. Russell Flegal

Charles Dunlap

Four airborne particulate records from ombrotrophic peat bogs in southern Norway, extending back 300 years, have been measured for chronology, lead concentration, and lead isotope composition. Since southern Norway receives an airborne lead signal that accumulates emissions from the European continent, the trend in the four bog records can be used to correlate previously reported measurements from France, Switzerland, England, and Greenland that cover different ranges of time. When these are compiled, the integrated European record that emerges spans the last 2300 years of human influence on lead in the air over Europe and suggests human control of lead in …


The Hofmann Rearrangement Using Household Bleach: Synthesis Of 3-Nitroaniline, Ram S. Mohan, Keith A. Monk Dec 1998

The Hofmann Rearrangement Using Household Bleach: Synthesis Of 3-Nitroaniline, Ram S. Mohan, Keith A. Monk

Ram S. Mohan

No abstract provided.


Oxidation Of Benzoins To Benzils Using Bismuth(Iii) Nitrate-Copper(Ii) Acetate, Ram S. Mohan, Steven A. Tymonko, Bryce A. Nattier Dec 1998

Oxidation Of Benzoins To Benzils Using Bismuth(Iii) Nitrate-Copper(Ii) Acetate, Ram S. Mohan, Steven A. Tymonko, Bryce A. Nattier

Ram S. Mohan

Benzoins are oxidized to benzils in excellent yields by 0.4 equivalents of Bi(NO3)3.5H20 and 4 mol% of Cu(OAc)23)3.5H20 is a stable, inexpensive, commercially available solid. The relatively low cost and low toxicity of bismuth(Ill) nitrate makes this procedure a particularly attractive method for oxidation of benzoins.


Multi-Modal Retrieval Of Trademark Images Using Global Similarity, S Ravela, R. Manmatha Dec 1998

Multi-Modal Retrieval Of Trademark Images Using Global Similarity, S Ravela, R. Manmatha

R. Manmatha

In this paper a system for multi-modal retrieval of trademark images is presented. Images are characterized and retrieved using associated text and visual appearance. A user initiates retrieval for similar trademarks by typing a text query. Subsequent searches can be performed by visual appearance or using both appearance and text information. Textual information associated with trademarks is searched using the INQUERY search engine. Images are searched visually using a method for global image similarity by appearance developed in this paper. Images are filtered with Gaussian derivatives and geometric features are computed from the filtered images. The geometric features used here …