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Displaying 36476 - 36500 of 74045

Resonant microwave power absorption and relaxation of the energy levels of the molecular nanomagnet Fe 8 using superconducting quantum interference device-based magnetometry

August 15, 2005
Author(s)
Brant Cage, Stephen E. Russek, David Zipse, Micah North, Naresh S. Dalal
Energy levels and saturation of molecular nanomagnet Fe 8 crystals were investigated using a 95 and 141 GHz electron paramagnetic resonance (EPR) technique based on a standard superconducting quantum intererence device (SQUID) magnetometer. The technique

Standards and Standardization of Molecular Diagnostics

August 15, 2005
Author(s)
J P. Jakupciak, C D. O'Connell
DNA has become a major target for clinical laboratory testing over the past 5 years, and RNA testing is emerging for infectious disease and gene expression (1). To normalize laboratory results across different technology platforms as well as between

Exact Solution of a Field Theory Model of Frontal Photopolymerization

August 11, 2005
Author(s)
James A. Warren, J Cabral, Jack F. Douglas
Frontal photopolymerization (FPP) provides a versatile method for the rapid fabrication of solid polymer network materials by exposing photosensitive molecules to light. Dimensional control of structures created by this process is crucial in applications

High resolution, high collection efficiency in numerical aperture increasing lens microscopy of individual quantum dots

August 9, 2005
Author(s)
Zhiheng H. Liu, B. B. Goldberg, Stephen B. Ippolito, Anthony N. Vamivakas, M. S. Unlu, Richard Mirin
We demonstrate the application of a subsurface solid immersion technique to the photoluminescence spectroscopy of individual quantum dots. Contrasted with the conventional solid immersion microscopy, we used a numerical aperture increasing lens and moved

Chip-Scale Atomic Clocks at NIST

August 7, 2005
Author(s)
John E. Kitching, Svenja A. Knappe, Li-Anne Liew, John Moreland, Hugh Robinson, P Schwindt, V Shah, Vladislav Gerginov, Leo W. Hollberg
We describe recent efforts to develop microfabricated atomic frequency references capable of supporting a wide variety of commercial and military systems such as global positioning and wireless communication. These devices are anticipated to eventually

Uncertainty Budgets for Comparison Calibrations of Thermocouples

August 7, 2005
Author(s)
Dean C. Ripple, K Garrity
By means of concrete examples, we discuss the determination of an uncertainty budget for calibration of thermocouples by comparison techniques. In the first example, the calibration of a type T thermocouple (copper versus copper-nickel alloy) in a stirred

Injection Locking and Phase Control of Spin Transfer Nano-Oscillators

August 5, 2005
Author(s)
William Rippard, Matthew Pufall, Shehzaad F. Kaka, Thomas J. Silva, Stephen E. Russek, Jordan A. Katine
We have directly measured phase locking of spin transfer oscillators to an injected ac current. The oscillators lock to signals up to several hundred megahertz away from their natural oscillation frequencies, depending on the relative strength of the input

Long-Lived Qubit Memory Using Atomic Ions

August 5, 2005
Author(s)
C. Langer, R Ozeri, John D. Jost, J Chiaverini, B. L. DeMarco, A. Ben-Kish, Brad R. Blakestad, Joseph W. Britton, David Hume, Wayne M. Itano, Dietrich G. Leibfried, Rainer Reichle, Till P. Rosenband, Tobias Schaetz, Piet Schmidt, David J. Wineland
We demonstrate experimentally a robust quantum memory using a magnetic-field-independent hyperfine transition in 9Be + atomic ioin qubits at a magnetic field B=0.01194 T. We observe the single physical qubit memory coherence time to be greater than 10

Shaped Pupil Coronagraphs for Planet Finding: Optimization, Manufacturing, and Experimental Results

August 4, 2005
Author(s)
Jeremy Kasdin, Ruslan Belikov, James A. Beall, Robert J. Vanderbei, Michael G. Littman, Michael Carr, Amir Give''on
Current plans call for the first Terrestrial Planet Finder mission, TPF-C, to be a monolithic space telescope with a coronagraph for achieving high contrast. Our group at Princeton pioneered the concept of shaped pupils for high contrast imaging and planet

Spectral Matching With an LED-Based Spectrally Tunable Light Source

August 4, 2005
Author(s)
Irena Fryc, Steven W. Brown, Yoshihiro Ohno
A spectrally tunable light source using a large number of LEDs and an integrating sphere has been designed and constructed at the National Institute of Standards and Technology (NIST). The source is designed to have a capability of producing any visible

Uncertainties in Spherical Near-Field Antenna Measurements

August 3, 2005
Author(s)
Michael H. Francis, Ronald C. Wittmann, Jin-Seob Kang
A general approach is presented for estimating uncertainties in far-field parameters obtained from spherical near-field antenna measurements. The error is approximately bounded in terms of the uncertainty of the probe's receiving pattern and the

Scattering Length Determination From Trapped Pairs of Atoms

August 2, 2005
Author(s)
S Shresta, Eite Tiesinga, E L. Bolda, Carl J. Williams
A method is described for estimating effective scattering lengths via spectroscopy on a trapped pair of atoms. The method relies on the well known phenomena that the energy levels of two atoms in a harmonic trap are shifted by their collisional interaction

4th Annual PKI R&D Workshop "Multiple Paths to Trust" Proceedings

August 1, 2005
Author(s)
Clifford Neuman, William Polk, Nelson Hastings
NIST hosted the fourth annual Public Key Infrastructure (PKI) Research Workshop on April 19-21, 2005. The two and a half day event brought together PKI experts from academia, industry, and government to explore the remaining challenges in deploying public

A Fiber Probe for CMM Measurements of Small Features

August 1, 2005
Author(s)
Jack A. Stone Jr., Balasubramanian Muralikrishnan, John R. Stoup
We report on performance of a new form of fiber probe, which can be used in conjunction with a coordinate measuring machine (CMM) for microfeature measurement. The probe stylus is a glass fiber with a small ball (?75 ?m diameter) glued to the end. When the

Analysis and Evaluation for STEP-Based Electro-Mechanical Assemblies

August 1, 2005
Author(s)
XuanFang Zha, Sebti Foufou, Sudarsan Rachuri, Ram D. Sriram
In this paper, we propose an integrated approach to assemblability analysis and evaluation for STEP-based (STandard for the Exchange of Product model data, officially ISO 10303) electro-mechanical products. First, two assembly representational models are

ATRP in Microchannels

August 1, 2005
Author(s)
Kathryn L. Beers, Tao Wu, Chang Xu
The range of accessible well-defined synthetic polymers expanded dramatically with the discovery of atom transfer radical polymerization (ATRP). In fact, there are so many options for variations of block, statistical and gradient copolymers, not to mention

Calibration and Standardization Issues of UV Sensors for Water Disinfection

August 1, 2005
Author(s)
Thomas C. Larason, Yoshihiro Ohno
Ultraviolet radiation (UV) effectively inactivates common pathogens found in ground and surface waters such as Cryptosporidium, Giardia and most bacterial pathogens. Water treatment facilities recently started using ultraviolet radiation for disinfection
Displaying 36476 - 36500 of 74045
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