68,078 research outputs found
Neutron die-away experiment for remote analysis of the surface of the moon and the planets, phase 3
Continuing work on the two die-away measurements proposed to be made in the combined pulsed neutron experiment (CPNE) for analysis of lunar and planetary surfaces is described. This report documents research done during Phase 3. A general exposition of data analysis by the least-squares method and the related problem of the prediction of variance is given. A data analysis procedure for epithermal die-away data has been formulated. In order to facilitate the analysis, the number of independent material variables has been reduced to two: the hydrogen density and an effective oxygen density, the latter being determined uniquely from the nonhydrogeneous elemental composition. Justification for this reduction in the number of variables is based on a set of 27 new theoretical calculations. Work is described related to experimental calibration of the epithermal die-away measurement. An interim data analysis technique based solely on theoretical calculations seems to be adequate and will be used for future CPNE field tests
Method and apparatus for aligning a laser beam projector Patent
Laser beam projector for continuous, precise alignment between target, laser generator, and astronomical telescope during trackin
Method of directing a laser beam with very high accuracy
System will collimate and direct an argon laser beam with high angular tracking accuracy at objects on the moons surface. It can be adapted to missile and satellite tracking
Slow light in degenerate Fermi gases
We investigate the effect of slow light propagating in a degenerate atomic
Fermi gas. In particular we use slow light with an orbital angular momentum. We
present a microscopic theory for the interplay between light and matter and
show how the slow light can provide an effective magnetic field acting on the
electrically neutral fermions, a direct analogy of the free electron gas in an
uniform magnetic field. As an example we illustrate how the corresponding de
Haas-van Alphen effect can be seen in a neutral gas of fermions.Comment: Slightly updated. Phys. Rev. Lett. 93, 033602 (2004
Study to define and verify the personal oral hygiene requirements for extended manned space flight Annual report, 1 Jul. 1968 - 30 Jun. 1969
Astronaut oral hygiene requirements for extended manned space fligh
Polarisation rotation of slow light with orbital angular momentum in ultracold atomic gases
We consider the propagation of slow light with an orbital angular momentum
(OAM) in a moving atomic medium. We have derived a general equation of motion
and applied it in analysing propagation of slow light with an OAM in a rotating
medium, such as a vortex lattice. We have shown that the OAM of slow light
manifests itself in a rotation of the polarisation plane of linearly polarised
light. To extract a pure rotational phase shift, we suggest to measure a
difference in the angle of the polarisation plane rotation by two consecutive
light beams with opposite OAM. The differential angle is
proportional to the rotation frequency of the medium
and the winding number of light, and is inversely proportional to the
group velocity of light. For slow light the angle should
be large enough to be detectable. The effect can be used as a tool for
measuring the rotation frequency of the medium.Comment: 5 pages, 1 figur
Phasing Into Retirement
Employers have been launching phased retirement programs to help workers navigate the transition from work to retirement more effectively. This paper examines the experience of the phased retirement system for tenured faculty in the University of North Carolina system. After phased retirement was introduced, there was a sizable increase in the overall separation rate in the system. A multinomial logit model of the retirement decision as a function of pension incentives, employee performance, demographics, and campus characteristics is developed. The key empirical result is that the odds of entering phased retirement are strongly and inversely related to employee performance, as measured by recent pay increases.
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