15,129 research outputs found
On Deriving Space-Time From Quantum Observables and States
We prove that, under suitable assumptions, operationally motivated data
completely determine a space-time in which the quantum systems can be
interpreted as evolving. At the same time, the dynamics of the quantum system
is also determined. To minimize technical complications, this is done in the
example of three-dimensional Minkowski space.Comment: 19 pages, to appear in Communications in Mathematical Physics; minor
corrections mad
Teachers guide for building and operating weather satellite ground stations for high school science
A number of colleges and universities are operating APT direct readout stations. However, high school science teachers have often failed to realize the potential of meteorological satellites and their products as unique instructional tools. The ability to receive daily pictures from these satellites offers exciting opportunities for secondary school teachers and students to assemble the electronic hardware and to view real time pictures of Earth from outer space. The station and pictures can be used in the classroom to develop an approach to science teaching that could span many scientific disciplines and offer many opportunities for student research and participation in scientific processes. This can be accomplished with relatively small expenditures of funds for equipment. In most schools some of the equipment may already be available. Others can be constructed by teachers and/or students. Yet another source might be the purchase of used equipment from industry or through the government surplus channels. The information necessary for individuals unfamiliar with these systems to construct a direct readout for receiving real time APT photographs on a daily basis in the classroom is presented
Clearing and settlement of U.S. dollar payments: back to the future?
Federal Reserve banks - Service charges ; Payment systems
Theoretical and material studies on thin-film electroluminescent devices
The effect of surface nucleation processes on the quality of ZnS layers grown on (001) GaAs substrates by molecular beam epitaxy is reported. Reflection high energy electron diffraction indicated that nucleation at high temperatures produced more planar surfaces than nucleation at low temperatures, but the crystalline quality as accessed by x ray double crystal diffractometry is relatively independent of nucleation temperature. A critical factor in layer quality was the initial roughness of the GaAs surfaces
On the stability of the boundary of the geomagnetic field
Dynamic response determination of geomagnetic field boundary in steady solar wind to small initial disturbance from equilibrium configuratio
Transonic wind-tunnel tests of an F-8 airplane model equipped with 12 and 14-percent thick oblique wings
An experimental investigation was conducted in the Ames 14-foot transonic wind tunnel to study the aerodynamic performance and stability characteristics of a 0.087-scale model of an F-8 airplane fitted with an oblique wing. Two elliptical planform (axis ratio = 8:1) wings, each having a maximum thickness of 12 and 14 percent, were tested. Longitudinal stability data were obtained with no wing and with each of the two wings set at sweep angles of 0, 45, and 60 deg. Lateral directional stability data were obtained for the 12 percent wing only. Test Mach numbers ranged from 0.6 to 1.2 in the unit Reynolds number range from 11.2 to 13.1 million per meter. Angles of attack were between -6 and 22 deg at zero sideslip. Angles of sideslip were between -6 and +6 deg for two angles of attack, depending upon the wing configuration
A Pulsed Synchrotron for Muon Acceleration at a Neutrino Factory
A 4600 Hz pulsed synchrotron is considered as a means of accelerating cool
muons with superconducting RF cavities from 4 to 20 GeV/c for a neutrino
factory. Eddy current losses are held to less than a megawatt by the low
machine duty cycle plus 100 micron thick grain oriented silicon steel
laminations and 250 micron diameter copper wires. Combined function magnets
with 20 T/m gradients alternating within single magnets form the lattice. Muon
survival is 83%.Comment: 4 pages, 1 figures, LaTeX, 5th International Workshop on Neutrino
Factories and Superbeams (NuFact 03), 5-11 Jun 2003, New Yor
Remarks on Causality in Relativistic Quantum Field Theory
It is shown that the correlations predicted by relativistic quantum field
theory in locally normal states between projections in local von Neumann
algebras \cA(V_1),\cA(V_2) associated with spacelike separated spacetime
regions have a (Reichenbachian) common cause located in the union of
the backward light cones of and . Further comments on causality and
independence in quantum field theory are made.Comment: 10 pages, Latex, Quantum Structures 2002 Conference Proceedings
submission. Minor revision of the order of definitions on p.
Jupiter: Its infrared spectrum from 10 to 40 microns
Spectral measurements of the thermal radiation from Jupiter in the 16-40 micrometer band were analyzed under the assumption that pressure broadened H2 transitions are responsible for the bulk of the infrared opacity over most of this spectral interval. Both the vertical pressure-temperature profile and the hydrogen mixing ratio were determined. The derived value of the molecular hydrogen mixing ratio, 0.89 + or - 0.11, is consistent with the solar value, 0.86
A Fluid Model for the Interaction of the Solar Wind and the Geomagnetic Field
Solar wind and geomagnetic field interaction in terms of continuum theory of fluid flo
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