66,492 research outputs found
Development of a polyimide for use as a temperature and solvent resistant sealant
Polyimide developed by the interaction of benzophenone tetracarboxylic dianhydride, polyoxypropylene diamine, and oxydianiline is used for fuel tanks that are exposed to extreme temperatures
The administration of research. An interpretive summary of the Proceedings of the National Conference on the Administration of Research, 1947-1964
Research management and administration - summary of conference proceeding
The massive binary population of the starburst cluster Westerlund 1
We present initial results from a long-baseline radial velocity survey for massive binaries in the cluster Westerlund 1. Four systems are examined: the dust-producing WC binary W239, the double-lined eclipsing binary W13, and the single-lined B0 supergiants W43a and W3003. Finally, the evolutionary implications for the population of massive stars in Westerlund 1 are discussed
Fast initialization of a high-fidelity quantum register using optical superlattices
We propose a method for the fast generation of a quantum register of
addressable qubits consisting of ultracold atoms stored in an optical lattice.
Starting with a half filled lattice we remove every second lattice barrier by
adiabatically switching on a superlattice potential which leads to a long
wavelength lattice in the Mott insulator state with unit filling. The larger
periodicity of the resulting lattice could make individual addressing of the
atoms via an external laser feasible. We develop a Bose-Hubbard-like model for
describing the dynamics of cold atoms in a lattice when doubling the lattice
periodicity via the addition of a superlattice potential. The dynamics of the
transition from a half filled to a commensurately filled lattice is analyzed
numerically with the help of the Time Evolving Block Decimation algorithm and
analytically using the Kibble-Zurek theory. We show that the time scale for the
whole process, i.e. creating the half filled lattice and subsequent doubling of
the lattice periodicity, is significantly faster than adiabatic direct quantum
freezing of a superfluid into a Mott insulator for large lattice periods. Our
method therefore provides a high fidelity quantum register of addressable
qubits on a fast time scale.Comment: 22 pages, 9 figures, IOP style. Revised version to appear in NJ
Nature of the spin liquid state of the Hubbard model on honeycomb lattice
Recent numerical work (Nature 464, 847 (2010)) indicates the existence of a
spin liquid phase (SL) that intervenes between the antiferromagnetic and
semimetallic phases of the half filled Hubbard model on a honeycomb lattice. To
better understand the nature of this exotic phase, we study the quantum
spin model on the honeycomb lattice, which provides an effective
description of the Mott insulating region of the Hubbard model. Employing the
variational Monte Carlo approach, we analyze the phase diagram of the model,
finding a phase transition between antiferromagnet and an unusual SL
state at , which we identify as the SL phase of the
Hubbard model. At higher we find a transition to a
dimerized state with spontaneously broken rotational symmetry.Comment: 5 pages, 6 figure
Final-state interactions and superscaling in the semi-relativistic approach to quasielastic electron and neutrino scattering
The semi-relativistic approach to electron and neutrino quasielastic
scattering from nuclei is extended to include final-state interactions.
Starting with the usual non-relativistic continuum shell model, the problem is
relativized by using the semi-relativistic expansion of the current in powers
of the initial nucleon momentum and relativistic kinematics. Two different
approaches are considered for the final-state interactions: the Smith-Wambach
2p-2h damping model and the Dirac-equation-based potential extracted from a
relativistic mean-field plus the Darwin factor. Using the latter the scaling
properties of and cross sections for intermediate
momentum transfers are investigated.Comment: 36 pages, 17 figure
The Rhode Island Automobile Directory: The Complete List of Automobile Owners, Manufacturers and Dealers Registered in Rhode Island
An assessment of the impact of water impoundment and diversion structures on vegetation in Southern Arizona
High-altitude color infrared photography was used to survey existing conditions, both upstream and downstream, from nineteen diversion structures in Southern Arizona to determine their effect upon vegetation health, vigor, and cover. A diversion structure is defined as a man/made feature constructed to control storm runoff. The results are used to determine the policy for future structure design
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