14 research outputs found
Theory and applications of atomic and ionic polarizabilities
Atomic polarization phenomena impinge upon a number of areas and processes in
physics. The dielectric constant and refractive index of any gas are examples
of macroscopic properties that are largely determined by the dipole
polarizability. When it comes to microscopic phenomena, the existence of
alkaline-earth anions and the recently discovered ability of positrons to bind
to many atoms are predominantly due to the polarization interaction. An
imperfect knowledge of atomic polarizabilities is presently looming as the
largest source of uncertainty in the new generation of optical frequency
standards. Accurate polarizabilities for the group I and II atoms and ions of
the periodic table have recently become available by a variety of techniques.
These include refined many-body perturbation theory and coupled-cluster
calculations sometimes combined with precise experimental data for selected
transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index
measurements in microwave cavities, ab initio calculations of atomic structures
using explicitly correlated wave functions, interferometry with atom beams, and
velocity changes of laser cooled atoms induced by an electric field. This
review examines existing theoretical methods of determining atomic and ionic
polarizabilities, and discusses their relevance to various applications with
particular emphasis on cold-atom physics and the metrology of atomic frequency
standards.Comment: Review paper, 44 page
Quantum information with Rydberg atoms
Rydberg atoms with principal quantum number n >> 1 have exaggerated atomic
properties including dipole-dipole interactions that scale as n^4 and radiative
lifetimes that scale as n^3. It was proposed a decade ago to take advantage of
these properties to implement quantum gates between neutral atom qubits. The
availability of a strong, long-range interaction that can be coherently turned
on and off is an enabling resource for a wide range of quantum information
tasks stretching far beyond the original gate proposal. Rydberg enabled
capabilities include long-range two-qubit gates, collective encoding of
multi-qubit registers, implementation of robust light-atom quantum interfaces,
and the potential for simulating quantum many body physics. We review the
advances of the last decade, covering both theoretical and experimental aspects
of Rydberg mediated quantum information processing.Comment: accepted version, to appear in Rev. Mod. Phys., 40 figures
NASA Tech Briefs, July/August 1987
Topics include: NASA TU Services; New Product Ideas; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Fabrication Technology; Machinery; Mathematics and Information Sciences; Life Sciences
Novel Research about Biomechanics and Biomaterials Used in Hip, Knee and Related Joints
Joint replacement is a very successful medical treatment. However, the survivorship of hip, knee, shoulder, and other implants is limited. The degradation of materials and the immune response against degradation products or an altered tissue loading condition as well as infections remain key factors of their failure. Current research in biomechanics and biomaterials is trying to overcome these existing limitations. This includes new implant designs and materials, bearings concepts and tribology, kinematical concepts, surgical techniques, and anti-inflammatory and infection prevention strategies. A careful evaluation of new materials and concepts is required in order to fully assess the strengths and weaknesses and to improve the quality and outcomes of joint replacements. Therefore, extensive research and clinical trials are essential. The main aspects that are addressed in this Special Issue are related to new material, design and manufacturing considerations of implants, implant wear and its potential clinical consequence, implant fixation, infection-related material aspects, and taper-related research topics. This Special Issue gives an overview of the ongoing research in those fields. The contributions were solicited from researchers working in the fields of biomechanics, biomaterials, and bio- and tissue-engineering
NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 14)
This issue of the Index Section contains entries for 3512 patent and applications for patent citations covering the period May 1969 through December 1978. The Index Section contains five indexes --- subject, inventor, source, number, and accession number
NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 26)
A subject index is provided for over 4300 patents and patent applications for the period May 1969 through December 1984. Additional indexes list personal authors, corporate authors, contract numbers, NASA case numbers, U.S. patent class numbers, U.S. patent numbers, and NASA accession numbers
Transportation in Iowa: A Historical Summary, 1988
“This book traces the development of transportation in Iowa from territorial days to the 19 80s. It shows the evolution of the transportation systems; how they originated, progressed and functioned; their structural organizations; effectiveness in overcoming obstacles, under the guidance of state and federal legislation; and their impact upon the development of the state.” – From the Prologue, page xii
NASA patent abstracts bibliography: A continuing bibliography. Section 2: Indexes (supplement 45)
A subject index is provided for over 5600 patents and patent applications for the period May 1969 through June 1994. Additional indexes list personal authors, corporate authors, contract numbers, NASA case numbers, U.S. patent class numbers, U.S. patent numbers, and NASA accession numbers