97,065 research outputs found
Geoscience and a Lunar Base: A Comprehensive Plan for Lunar Exploration
This document represents the proceedings of the Workshop on Geoscience from a Lunar Base. It describes a comprehensive plan for the geologic exploration of the Moon. The document begins by explaining the scientific importance of studying the Moon and outlines the many unsolved problems in lunar science. Subsequent chapters detail different, complementary approaches to geologic studies: global surveys, including orbiting spacecraft such as Lunar Observer and installation of a global geophysical network; reconnaissance sample return mission, by either automated rovers or landers, or by piloted forays; detailed field studies, which involve astronauts and teleoperated robotic field geologists. The document then develops a flexible scenario for exploration and sketches the technological developments needed to carry out the exploration scenario
Bounds on quantum communication via Newtonian gravity
Newtonian gravity yields specific observable consequences, the most striking
of which is the emergence of a force. In so far as communication can
arise via such interactions between distant particles, we can ask what would be
expected for a theory of gravity that only allows classical communication. Many
heuristic suggestions for gravity-induced decoherence have this restriction
implicitly or explicitly in their construction. Here we show that communication
via a force has a minimum noise induced in the system when the
communication cannot convey quantum information, in a continuous time analogue
to Bell's inequalities. Our derived noise bounds provide tight constraints from
current experimental results on any theory of gravity that does not allow
quantum communication.Comment: 13 pages, 1 figur
Biological Monitoring of the Capsule Mechanical Training Model During Assembly in the Sterilization Assembly Development Laboratory
Microbial burden sterilization assembly procedure development using rigorous monitoring progra
A Feasibility Study of Liquid Sterile Insertion
Technique for sterile insertion of liquids into previously sterilized spacecraf
Teleprinter uses thermal printing technique
Alphameric/facsimile printer receives serial digital data in the form of a specified number of bits per group and prints it on thermally sensitive paper. A solid state shift-register memorizes the incoming serial digital data
Research in far ultraviolet filtering for space optical systems
Design and fabrication of multilayer interference filters for ultraviole
Spectral properties of the tandem Jackson network, seen as a quasi-birth-and-death process
Quasi-birth-and-death (QBD) processes with infinite ``phase spaces'' can
exhibit unusual and interesting behavior. One of the simplest examples of such
a process is the two-node tandem Jackson network, with the ``phase'' giving the
state of the first queue and the ``level'' giving the state of the second
queue. In this paper, we undertake an extensive analysis of the properties of
this QBD. In particular, we investigate the spectral properties of Neuts's
R-matrix and show that the decay rate of the stationary distribution of the
``level'' process is not always equal to the convergence norm of R. In fact, we
show that we can obtain any decay rate from a certain range by controlling only
the transition structure at level zero, which is independent of R. We also
consider the sequence of tandem queues that is constructed by restricting the
waiting room of the first queue to some finite capacity, and then allowing this
capacity to increase to infinity. We show that the decay rates for the finite
truncations converge to a value, which is not necessarily the decay rate in the
infinite waiting room case. Finally, we show that the probability that the
process hits level n before level 0 given that it starts in level 1 decays at a
rate which is not necessarily the same as the decay rate for the stationary
distribution.Comment: Published at http://dx.doi.org/10.1214/105051604000000477 in the
Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute
of Mathematical Statistics (http://www.imstat.org
The Angular Size and Proper Motion of the Afterglow of GRB 030329
The bright, nearby (z=0.1685) gamma-ray burst of 29 March 2003 has presented
us with the first opportunity to directly image the expansion of a GRB. This
burst reached flux density levels at centimeter wavelengths more than 50 times
brighter than any previously studied event. Here we present the results of a
VLBI campaign using the VLBA, VLA, Green Bank, Effelsberg, Arecibo, and
Westerbork telescopes that resolves the radio afterglow of GRB 030329 and
constrains its rate of expansion. The size of the afterglow is found to be
\~0.07 mas (0.2 pc) 25 days after the burst, and 0.17 mas (0.5 pc) 83 days
after the burst, indicating an average velocity of 3-5 c. This expansion is
consistent with expectations of the standard fireball model. We measure the
projected proper motion of GRB 030329 in the sky to <0.3 mas in the 80 days
following the burst. In observations taken 52 days after the burst we detect an
additional compact component at a distance from the main component of 0.28 +/-
0.05 mas (0.80 pc). The presence of this component is not expected from the
standard model.Comment: 12 pages including 2 figures, LaTeX. Accepted to ApJ Letters on May
14, 200
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