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Displaying 42751 - 42775 of 74165

Brewster-Angle Attenuator for THz Pulses

December 1, 2002
Author(s)
A G. VanEngen Spivey, S T. Cundiff
A variable attenuator for terahertz (THz) pulses is developed on the based of the change in reflectivity of lithium niobate wafers with incident angle in a Brewster configuration. We can vary the THz field transmission from 22% to 54%, a change of a factor

Cavitation of Polyethylene During Extrusion Processing Instabilities

December 1, 2002
Author(s)
Y Son, Kalman D. Migler
We present observations of cavitation that occur inside a capillary die during extrusion of a polyethylene. This phenomenon is observed over the last 1.5 mm of the capillary tube immediately upstream of the exit. We observe spontaneous formation of voids

Chain Conformation in Ultrathin Polymer Films

December 1, 2002
Author(s)
Ronald L. Jones, Christopher Soles, Francis W. Starr, Eric K. Lin, Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, Wen-Li Wu, D L. Goldfarb, M Angelopolous
Using Small Angle Neutron Scattering (SANS), we present the first quantitative measurements of the 3-dimensional conformation of macromolecules in thin polymer films of D RG,Bulk. Where D is the film thickness and RG,Bulk is the bulk radius of gyration

Characterisation of the Response of Chromium-Doped Alumina Screens in the Vacuum Ultraviolet Using Synchrotron Radiation

December 1, 2002
Author(s)
James K. McCarthy, A Baciero, B Zurro, Uwe Arp, Charles Tarrio, Thomas B. Lucatorto, A Morono, P Martin, E R. Hodgson
We have measured the response of chromium-doped alumina screens to vacuum ultraviolet radiation and derived quantum efficiency curves for the energy range from 30 to 300 eV. A model is presented to explain the structure in this curve. In addition, the

Copper Oxide Precipitates in NBS Standard Reference Material 482

December 1, 2002
Author(s)
Eric S. Windsor, R Carlton, John G. Gillen, Scott A. Wight, David S. Bright
Copper oxide has been detected in the copper containing alloys of Standard Reference Material (SRM) 482. This occurrence is significant because it represents heterogeneity within a standard reference material that was certified to be homogeneous on a

Database-Assisted Wind Load Capacity Estimates for Low-Rise Steel Frames

December 1, 2002
Author(s)
S Jang, L L. Lu, Fahim H. Sadek, Emil Simiu
A comparative study is presented of the estimated wind load capacities of low-rise steel building frames based on loading patterns (magnitude and distribution) established from aerodynamic databases on the one hand, and on patterns specified in the ASCE 7

Design and Use of a Peptide Nucleic Acid for Detection of the Heteroplasmic Low-Frequency Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-Like Episodes (MELAS) Mutation in Human Mitochondrial DNA

December 1, 2002
Author(s)
Diane K. Hancock, Frederick P. Schwarz, F H. Song, L J. Wong, Barbara C. Levin
Most pathogenic human mitochondrial DNA (mtDNA) mutations are Heteroplasmic and are difficult to detect when present at very low levels in a population of normal mtDNA molecules. This paper describes a simple methodology to detect low levels of the single

Diederik J. Korteweg, Pioneer of Criticality

December 1, 2002
Author(s)
Johanna Levelt Sengers, A H. Levelt
Dutch mathematician Diederik Johannes Korteweg (1848-1941), pictured in figure 1, is best known for the 1895 paper he wrote with his student Gustav De Vries. This paper on the propagation of soliton waves in channels, has, in recent decades, been widely

Direct Separation of Short Range Order in Intermixed Nanocrystalline and Amorphous Phases

December 1, 2002
Author(s)
Charles E. Bouldin, A I. Frenkel, A V. Kolobov, I K. Robinson, J O. Cross, Y Maeda
Diffraction Anomalous Fine Structure (DAFS) and Extended X-Ray Absorption Fine Structure (EXAFS) measurements have been combined to determine short-range order (SRO) about a single atomic type in a sample of mixed amorphous and nanocrystalline phases

Effect of Wind Velocity on Flame Spread in Microgravity

December 1, 2002
Author(s)
Kuldeep R. Prasad, S L. Olson, Y N. Nakamura, K K. Nishizawa, K. Ito, Takashi Kashiwagi
A three-dimensional, time-dependent model is developed describing ignition and subsequent transition to flame spread over a thermally thin cellulosic sheet heated by external radiation in a microgravity environment. A low Mach number approximation to the
Displaying 42751 - 42775 of 74165
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