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Search Publications

NIST Authors in Bold

Displaying 24376 - 24400 of 73930

The Dynamics of Unfolded Versus Folded tRNA: The Role of Electrostatic Interactions

September 21, 2011
Author(s)
Joon Ho Roh, Madhu Sudan Tyagi, Robert M. Briber, Sarah A. Woodson, Alexei P. Sokolov
We have used quasielastic neutron scattering spectroscopy to study the dynamics of unfolded tRNA under low ionic strength and tRNA folded through the addition of Mg 2+ in order to examine the role of electrostatic interactions in the dynamics of biological

The Role of Iron Redox State in the Genotoxicity of Ultrafine Superparamagnetic Iron Oxide Nanoparticles

September 21, 2011
Author(s)
Neenu Singh, Gareth J. Jenkins, Bryant C. Nelson, Bryce J. Marquis, Thierry G. Maffeis, Andy P. Brown, Paul M. Williams, Chris J. Wright, Shareen H. Doak
Ultrafine superparamagnetic iron oxide nanoparticles (USPION) hold great potential for revolutionising biomedical applications such as MRI, localised hyperthermia, and targeted drug delivery. Though evidence is increasing regarding the influence of

A Laser-Cooled Frequency Standard for GPS

September 20, 2011
Author(s)
Thomas P. Heavner, Stephan E. Barlow, Marc A. Weiss, Neil Ashby, Steven R. Jefferts
NIST is in an initial phase of developing a prototype laser-cooled atomic frequency standard (AFS) for potential use in a future GPS system. The expected fractional frequency stability or Allan deviation, ς y(τ), will be 2x10 -13 at one second, improving

High Pressure Route to Magnetic Monopole Dimers in Spin Ice

September 20, 2011
Author(s)
H. D. Zhou, S.T. Bramwell, J. G. Cheng, C. R. Wiebe, G. Li, L. Balicas, J. A. Bloxsom, H. J. Silverstein, J. S. Zhou, J. B. Goodenough, Jason S. Gardner
The gas of magnetic monopoles in spin ice is governed by one key parameter: the monopole chemical potential 1,2. A significant variation of this parameter could access hitherto undiscovered magnetic phenomena arising from monopole correlations, as observed

Real-Time Image Composition with Correction of Drift Distortion

September 20, 2011
Author(s)
Petr Cizmar, Andras Vladar, Michael T. Postek
In this article, a new scanning electron microscopy (SEM) image composition technique is de- scribed, which can significantly reduce drift-distortion related image corruptions. Drift-distortion commonly causes blur and distortions in the SEM images. Such

Trust Model for Security Automation Data 1.0 (TMSAD)

September 20, 2011
Author(s)
Harold Booth, Adam M. Halbardier
This report defines the Trust Model for Security Automation Data 1.0 (TMSAD), which permits users to establish integrity, authentication, and traceability for security automation data. Since security automation data is primarily stored and exchanged using

Block copolymer photonic gel for mechanochromic sensing

September 19, 2011
Author(s)
Edwin Chan, Joseph J. Walish, Edwin L. Thomas, Christopher Stafford
In this work, we describe a strategy based on mechanochromic sensing, the coupling between mechanical and optical properties, of a block copolymer photonic gel. Although this phenomena has been observed in many materials, we demonstrate this concept for

Development of the Metrology and Imaging of Cellulose Nanocrystals

September 19, 2011
Author(s)
Michael T. Postek, Andras Vladar, John A. Dagata, Natalia Farkas, Bin Ming, Ryan Wagner, Arvind Raman, Robert J. Moon, Ronald Sabo, Theodore H. Wegner, James Beecher
The development of metrology for nanoparticles is a significant challenge. Cellulose nanocrystals (CNC) are one group of nanoparticles that have high potential economic value but present substantial challenges to the development of the measurement science

Efficient quantum dot single photon extraction into an optical fiber using a nanophotonic directional coupler

September 19, 2011
Author(s)
Marcelo I. Davanco, Matthew T. Rakher, W. Wegscheider, Dieter Schuh, Antonio Badolato, Kartik A. Srinivasan
We demonstrate a spectrally broadband and efficient technique for collecting photoluminescence from a single InAs quantum dot directly into a standard single mode optical fiber. In this approach, an optical fiber taper waveguide is placed in contact with a

Extending single-photon optimized superconducting transition edge sensors beyond the single-photon counting regime

September 19, 2011
Author(s)
Thomas Gerrits, Brice R. Calkins, Nathan A. Tomlin, Adriana E. Lita, Alan L. Migdall, Sae Woo Nam, Richard P. Mirin
Photon number resolving transition-edge sensors (TES) are the cutting-edge enabling technology for high quantum efficiency photon number counting. The TES developed at NIST reliably show system detection efficiencies of more than 95%, and even approach 99%

Fully lithographic fiber-coupled cryogenic radiometer for picowatt powers

September 19, 2011
Author(s)
Nathan A. Tomlin, John H. Lehman, Sae Woo Nam
A new type of absolute cryogenic radiometer has been fabricated at the microscale level for direct substitution optical fiber power measurements. It consists of three parts: an absorber, electrical heater, and thermometer all on a single micro-machined

International comparisons of optical fiber power measurements

September 19, 2011
Author(s)
Igor Vayshenker, David J. Livigni, Xiaoyu X. Li, John H. Lehman
We discuss the results of optical fiber power meter (OFPM) measurements at 1310 and 1550 nm made by NIST and seven national measurement institutes (NMIs). We also describe transfer standards and the associated uncertainties. The comparisons show a

Modeling of Bolted Connections for Collapse Analysis of Steel Structures

September 19, 2011
Author(s)
Joseph A. Main, Fahim Sadek
In structural collapse scenarios, beam to column connections can be subjected to large rotations as the structure deforms, in addition to large axial forces associated with the development of catenary action. The capability of the connections to sustain

Reversed-Flow Chromatographic Determination of Binary Diffusion Coefficients

September 19, 2011
Author(s)
William S. McGivern, Jeffrey A. Manion
A reversed-flow chromatographic apparatus for the measurement of binary diffusion coefficients is described. Hydrocarbons are detected using flame ionization detection, and inert species can be detected by thermal conductivity. We have measured the binary

Review of Current Progress in Nanometrology with Helium Ions

September 19, 2011
Author(s)
Michael T. Postek, Andras Vladar, Bin Ming, Charles Archie
Scanning electron microscopy has been employed as an imaging and measurement tool for more than 50 years and it continues as a primary tool in many research and manufacturing facilities across the world. A new challenger to this work is the helium ion

Ultracold Atoms and Precise Time Standards

September 19, 2011
Author(s)
Gretchen K. Campbell, William D. Phillips
Experimental techniques of laser cooling and trapping, along with other cooling techniques have produced gaseous samples of atoms so cold that they are, for many practical purposes, in the quantum ground state of their center-of-mass motion. Such low

Absolute high-power laser measurements with a flowing water power meter

September 18, 2011
Author(s)
Christopher L. Cromer, Xiaoyu X. Li, John H. Lehman, Marla L. Dowell
We describe a novel flowing water power meter (FWOPM) for high-power laser radiometry in the range of 50 W to 10 kW. The FWOPM has several design features; a rotating mirror oriented at 45° with respect to the incoming radiation, a conical light-trapping

ANSI/NIST-ITL 1-2011 Requirements and Conformance Test Assertions

September 16, 2011
Author(s)
Christofer J. McGinnis, Dylan J. Yaga, Fernando L. Podio
The current version of the ANSI/NIST-ITL standard "Data Format for the Interchange of Fingerprint, Facial & Other Biometric Information" is specified in two parts. Part 1, ANSI/NIST-ITL 1-2007, specifies the traditional format, and Part 2, ANSI/NIST-ITL 2
Displaying 24376 - 24400 of 73930
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