33,889 research outputs found
Convoluted fabric for full-pressure gloves
Fabric, made of nylon ripstop coated with Neoprene, provides expansive and contractive mobility along posterior surface of glove fingers allowing maximum digital dexterity and tactility
Late time tails from momentarily stationary, compact initial data in Schwarzschild spacetimes
An L-pole perturbation in Schwarzschild spacetime generally falls off at late
times t as t^{-2L-3}. It has recently been pointed out by Karkowski,
Swierczynski and Malec, that for initial data that is of compact support, and
is initially momentarily static, the late-time behavior is different, going as
t^{-2L-4}. By considering the Laplace transforms of the fields, we show here
why the momentarily stationary case is exceptional. We also explain, using a
time-domain description, the special features of the time development in this
exceptional case.Comment: 7 pages, 5 figure
In an expanding universe, what doesn't expand?
The expansion of the universe is often viewed as a uniform stretching of
space that would affect compact objects, atoms and stars, as well as the
separation of galaxies. One usually hears that bound systems do not take part
in the general expansion, but a much more subtle question is whether bound
systems expand partially. In this paper, a very definitive answer is given for
a very simple system: a classical "atom" bound by electrical attraction. With a
mathemical description appropriate for undergraduate physics majors, we show
that this bound system either completely follows the cosmological expansion, or
-- after initial transients -- completely ignores it. This "all or nothing"
behavior can be understood with techniques of junior-level mechanics. Lastly,
the simple description is shown to be a justifiable approximation of the
relativistically correct formulation of the problem.Comment: 8 pages, 9 eps figure
Design considerations and test facilities for accelerated radiation effects testing
Test design parameters for accelerated dose rate radiation effects tests for spacecraft parts and subsystems used in long term mission (years) are detailed. A facility for use in long term accelerated and unaccelerated testing is described
Pharmacy - yesterday to-day and to-morrow : inaugural lecture delivered at Rhodes University
Inaugural lecture delivered at Rhodes University.Rhodes University Libraries (Digitisation
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