12,761 research outputs found
Design, test, and performance of the Mariner 5 temperature control reference
Design and performance of Mariner 5 temperature control assembly coating
Effects of space environment on composites: An analytical study of critical experimental parameters
A generalized methodology currently employed at JPL, was used to develop an analytical model for effects of high-energy electrons and interactions between electron and ultraviolet effects. Chemical kinetic concepts were applied in defining quantifiable parameters; the need for determining short-lived transient species and their concentration was demonstrated. The results demonstrates a systematic and cost-effective means of addressing the issues and show qualitative and quantitative, applicable relationships between space radiation and simulation parameters. An equally important result is identification of critical initial experiments necessary to further clarify the relationships. Topics discussed include facility and test design; rastered vs. diffuse continuous e-beam; valid acceleration level; simultaneous vs. sequential exposure to different types of radiation; and interruption of test continuity
Research on the use of space resources
The second year of a multiyear research program on the processing and use of extraterrestrial resources is covered. The research tasks included: (1) silicate processing, (2) magma electrolysis, (3) vapor phase reduction, and (4) metals separation. Concomitant studies included: (1) energy systems, (2) transportation systems, (3) utilization analysis, and (4) resource exploration missions. Emphasis in fiscal year 1982 was placed on the magma electrolysis and vapor phase reduction processes (both analytical and experimental) for separation of oxygen and metals from lunar regolith. The early experimental work on magma electrolysis resulted in gram quantities of iron (mixed metals) and the identification of significant anode, cathode, and container problems. In the vapor phase reduction tasks a detailed analysis of various process concepts led to the selection of two specific processes designated as ""Vapor Separation'' and ""Selective Ionization.'' Experimental work was deferred to fiscal year 1983. In the Silicate Processing task a thermophysical model of the casting process was developed and used to study the effect of variations in material properties on the cooling behavior of lunar basalt
Nuclear Quasi-Elastic Electron Scattering Limits Nucleon Off-Mass Shell Properties
The use of quasi-elastic electron nucleus scattering is shown to provide
significant constraints on models of the proton electromagnetic form factor of
off-shell nucleons. Such models can be constructed to be consistent with
constraints from current conservation and low-energy theorems, while also
providing a contribution to the Lamb shift that might potentially resolve the
proton radius puzzle in muonic hydrogen. However, observations of quasi-elastic
scattering limit the overall strength of the off-shell form factors to values
that correspond to small contributions to the Lamb shift.Comment: 11 pages, 2 figures. Resubmission to improve the clarity, and correct
possible misconception
MOBBING CALLS OF THE PHAINOPEPLA
When mobbing potential predators, male Phainopeplas (Phainopepla nitens) utter smoothly upswept vocalizations, unlike the harsh, staccato mobbing calls of other birds and mammals. A Phainopepla repeats this call as it approaches the bottom of its diving arc over the predator. We suggest that these calls do not serve to attract additional mobbers to the scene. Rather, they appear to emphasize the diving attacks directed toward the predator
Dark Energy and the mass of galaxy clusters
Up to now, Dark Energy evidences are based on the dynamics of the universe on
very large scales, above 1 Gpc. Assuming it continues to behave like a
cosmological constant on much smaller scales, I discuss its effects
on the motion of non-relativistic test-particles in a weak gravitational field
and I propose a way to detect evidences of at the scale of
about 1 Mpc: the main ingredient is the measurement of galaxy cluster masses.Comment: 5 pages, no figures, references adde
The vacuum state of quantum gravity contains large virtual masses
In the functional integral approach to quantum gravity, the quantum
configurations are usually treated to order hbar through a stationary phase
approximation around the saddle point of the action where spacetime is flat. We
show that from this point a "level line" in functional space departs, which
comprises a family of static non-flat metrics with zero scalar curvature,
depending on a continuous mass parameter. Furthermore, each of these metrics
can be perturbed by an arbitrary function in such a way to still satisfy the
condition Int(gR)d4x=0. We thus find a set of zero-modes of the gravitational
action which has non-vanishing measure in the functional space. These metrics
will contribute to the functional integral as vacuum fluctuations, on the same
footing as those near the saddle point.Comment: 13 pages, 4 figures; to appear in Class. Q. Gravit
The risk of cancer in primary care patients with hypercalcaemia: a cohort study using electronic records.
PublishedJournal ArticleBACKGROUND: The risk of cancer with hypercalcaemia in primary care is unknown. METHODS: This was a cohort study using calcium results in patients aged ⩾40 years in a primary care electronic data set. Diagnoses of cancer in the following year were identified. RESULTS: Participants (54 267) had calcium results: 1674 (3%) were ⩾2.6 mmol l(-1). Hypercalcaemia was strongly associated with cancer, especially in males: OR 2.92, 95% CI 2.17-3.93, P=<0.001; positive predictive value (PPV) 11.5%; females: OR 1.86, 95% CI 1.39-2.50, P<0.001: PPV 4.1%. CONCLUSIONS: Hypercalcaemia is strongly associated with cancer in primary care, with men at most risk, despite hypercalcaemia being more common in women
Phase transition from quark-meson coupling hyperonic matter to deconfined quark matter
We investigate the possibility and consequences of phase transitions from an
equation of state (EOS) describing nucleons and hyperons interacting via mean
fields of sigma, omega, and rho mesons in the recently improved quark-meson
coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag.
The transition to a mixed phase of baryons and deconfined quarks, and
subsequently to a pure deconfined quark phase, is described using the method of
Glendenning. The overall EOS for the three phases is calculated for various
scenarios and used to calculate stellar solutions using the
Tolman-Oppenheimer-Volkoff equations. The results are compared with recent
experimental data, and the validity of each case is discussed with consequences
for determining the species content of the interior of neutron stars.Comment: 12 pages, 14 figures; minor typos correcte
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