4,611 research outputs found
AS-204/LM-1 launch vehicle operational flight trajectory
Apollo Saturn-204/LM-1 launch vehicle operational flight trajector
Operation of an experimental algal gas exchanger for use in a CELSS
Concepts of a Closed Ecological Life Support System (CELSS) anticipate the use of photosynthetic organisms (higher plants and algae) for air revitalization. The rates of production and uptake of carbon dioxide and oxygen between the crew and the photosynthetic organisms are mismatched. An algal system used for gas exchange only will have the difficulty of an accumulation or depletion of these gases beyond physiologically tolerable limits (in a closed system the mismatch between assimilatory quotient (AQ) and respiratory quotient (RQ) is balanced by the operation of the waste processor). The results are given of a study designed to test the feasibility of using environmental manipulations to maintain physiologically appropriate atmospheres for algae and mice in a gas closed system. Specifically, the atmosphere behavior of this system is considered with algae grown on nitrate or urea and at different light intensities and optical densities. Manipulation of both allow operation of the system in a gas stable manner. Operation of such a system in a CELSS may be useful for reduction of buffer sizes, as a backup system for higher plant air revitalization and to supply extra oxygen to the waste processor or during crew changes
Lensing of Fast Radio Bursts by Plasma Structures in Host Galaxies
Plasma lenses in the host galaxies of fast radio bursts (FRBs) can strongly
modulate FRB amplitudes for a wide range of distances, including the
Gpc distance of the repeater FRB121102. To produce caustics, the lens'
dispersion-measure depth (), scale size (), and distance
from the source () must satisfy . Caustics produce strong
magnifications () on short time scales ( hours to days and
perhaps shorter) along with narrow, epoch dependent spectral peaks (0.1 to
1~GHz). However, strong suppression also occurs in long-duration (
months) troughs. For geometries that produce multiple images, the resulting
burst components will arrive differentially by s to tens of ms and
they will show different apparent dispersion measures, pc cm. Arrival time perturbations may mask any
underlying periodicity with period s. When arrival times differ by
less than the burst width, interference effects in dynamic spectra are
expected. Strong lensing requires source sizes smaller than , which can be satisfied by compact objects such as
neutron star magnetospheres but not by AGNs. Much of the phenomenology of the
repeating fast radio burst source FRB121102 is similar to lensing effects. The
overall picture can be tested by obtaining wideband spectra of bursts (from
to 10 GHz and possibly higher), which can also be used to characterize the
plasma environment near FRB sources. A rich variety of phenomena is expected
from an ensemble of lenses near the FRB source. We discuss constraints on
densities, magnetic fields, and locations of plasma lenses related to
requirements for lensing to occur.Comment: 11 pages, 7 figures, submitted to the Astrophysical Journa
Fourth Symposium on Chemical Evolution and the Origin and Evolution of Life
This symposium was held at the NASA Ames Research Center, Moffett Field, California, July 24-27, 1990. The NASA exobiology investigators reported their recent research findings. Scientific papers were presented in the following areas: cosmic evolution of biogenic compounds, prebiotic evolution (planetary and molecular), early evolution of life (biological and geochemical), evolution of advanced life, solar system exploration, and the Search for Extraterrestrial Intelligence (SETI)
Choice of Law in Product Liability Actions: Order for the Practitioner in a Reign of Chaos
The law on choice of law in the various states and in the federal courts is a veritable jungle, which, if the law can be found out, leads not to a rule of action but a reign of chaos dominated in each case by the judge\u27s informed guess as to what some other state than the one in which he sits would hold its law to be.
Products move today in streams of commerce which cross state, and often international, boundaries. When litigation concerning the liability for injury or damage caused by these products follows, choice of law plays a crucial role in determining the rights, remedies, and defenses available to the parties. In this article, the authors identify the issues which plaintiffs and defendants should consider in multi-jurisdictional product liability actions and set forth the basic rules for tort and contract choice of law
VLA Observations of Single Pulses from the Galactic Center Magnetar
We present the results of a 7-12 GHz phased-array study of the Galactic
center magnetar J1745-2900 with the Karl G. Jansky Very Large Array (VLA).
Using data from two 6.5 hour observations from September 2014, we find that the
average profile is comprised of several distinct components at these epochs and
is stable over day timescales and GHz frequencies. Comparison with
additional phased VLA data at 8.7 GHz shows significant profile changes on
longer timescales. The average profile at 7-12 GHz is dominated by the jitter
of relatively narrow pulses. The pulses in each of the four main profile
components seen in September 2014 are uncorrelated in phase and amplitude,
though there is a small but significant correlation in the occurrence of pulses
in two of the profile components. Using the brightest pulses, we measure the
dispersion and scattering parameters of J1745-2900. A joint fit of 38 pulses
gives a 10 GHz pulse broadening time of and a dispersion measure of . Both of these results are consistent with previous measurements,
which suggests that the scattering and dispersion measure of J1745-2900 may be
stable on timescales of several years.Comment: 20 pages, 10 figures, published in Ap
Life on ice, Antarctica and Mars
The study of the origin of life and the prospects for human exploration of Mars are two themes developed in a new 57-minute film, Life on Ice, Antarctica, and Mars, produced by the InnerSpace Foundation and WHRO Television for broadcast by the Public Broadcasting System (PBS). A brief explanation of the film and how it relates to the future human exploration of space is presented
Uniform cost accounting system for manufacturing implements and other farm operating equipment
The Association has had presented to it for several years the necessity for a uniform accounting system and for an accurate cost system, and we do not need to repeat the arguments advanced and the reasons given therefor. The present abnormal prices of materials, with increased costs in other directions, seem to make this an opportune time for the Association to adopt a uniform accounting system for manufacturers of implements and other farm operating equipment. We, therefore, submit herewith a simple system which we recommend to the Association, particularly for the guidance of organizations not already supplied with an adequate or satisfactory cost system
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