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At least 73 records · Page 4

Longer term consequences of the Short Take-Off and Landing (STOL) aircraft system

An assessment of the STOL aircraft and the various means of employing it are discussed in the light of a research study to evaluate the efficacy of such analyses. It was determined that current approaches to assessment are generally inadequate for investigating the full social consequences of implementing a new technology. It is stated that a meaningful methodology of technology assessment must reflect mechanisms underlying the relationship of technology to social change. Interrelated methods which are discussed are: (1) gaming and simulation as heurisitic approaches in analysis and inquiry, (2) long range planning and questions of the future, (3) planning theory as a background for critical analysis of policy planning, and (4) social theory, with particular emphasis on social change and systems theories.

Laporte, T. R.

The non-homogeneous accumulation model for terrestrial planet formation and the consequences for the atmosphere of Venus

The nonhomogeneous-accumulation model for the formation of the terrestrial planets is described, and its consequences for the formation of the Venusian atmosphere are assayed in the context of our knowledge of the composition of the earth and carbonaceous chondrites. The relative abundances of the low-temperature condensibles in the reservoirs at the earth's surface are applied to Venus. Although carbonaceous chondrites show similar properties for the chemically bound elements, they show large deficiencies for the rare gases. The major gases on Venus, by volume, are predicted to be 98.12% CO2, 1.86% N2 and 0.02% Ar-40.

Turekian, K. K.

Electrostatically unstable heat flow during solar flares and its consequences

This paper examines some of the consequences of an electrostatically unstable return current associated with heat conduction during a solar flare. It is noted that an electrostatically unstable return current will lead to strong hydrodynamic effects and more rapid magnetic-field thermalization if reconnection is the source of primary energy release during a solar flare.

Spicer, D. S.

Orbital topography and other astrophysical consequences of Rosen's bimetric theory of gravity

Since Rosen's bimetric theory of gravity provides at present a worthy devil's advocate for the black hole hypothesis, it is important for eventual observational work to elaborate the astrophysical consequences and possibilities peculiar to it. This work is begun by deriving the orbital topography of the spherically symmetric solution to Rosen's field equations - which is relevant to the behavior of relativistic axisymmetric accretion flows - and calculating predicted accretion disk efficiencies, which can be as much as 2.5 times higher than for a disk in Schwarzschild. Thereafter, a brief treatment of the shortest kinematic time scale and the time dilations for in-falling material is given. Finally it is shown that Birkhoff's theorem does not hold in Rosen's theory, and, therefore, that genuine gravitational monopole radiation is possible. The energy it carries, however, is not positive definite.

Stoeger, W. R.

Consequences of a past encounter of the earth with an interstellar cloud

In its motion through the Galaxy the sun may have suffered a number of encounters with dense interstellar clouds for which the number density of molecular hydrogen is in excess of 1000 per cu cm. Several authors have shown that this is sufficient density to stop the solar wind inside earth's orbit. Earth's atmosphere would be subjected to an interstellar H2 flux of more than 7 billion per sq cm/sec for periods of the order of 100,000 years. Simple scaling arguments are used to examine several consequences for earth's atmosphere: (1) the ionospheric F region would largely disappear; (2) the water-vapor content of the middle atmosphere would be greatly enhanced, reducing the mesospheric ozone concentrations and thereby lowering the average temperature and altitude of the mesopause; (3) as a result of (2), widespread mesospheric ice clouds would occur, increasing the planetary albedo; and (4) the resultant radiative cooling at the surface may have been sufficient to 'trigger' an ice age.

Mckay, C. P.

Twisted and warped disks as consequences of heavy halos

Observationally testable consequences of the hypothesis that galactic disks are confined less by their self-gravity than that of some hot stellar component are sought. Theoretical and observational studies are reviewed which suggest that elliptical galaxies are typically triaxial in form. It is argued that any hot stellar component is likely to be similarly spherical. The motion of a galactic disk about such a population is calculated. Within the plane the flow is to first order along similar concentric ellipses and without of the plane, provided that certain conditions on the background field are met, an oscillation may be excited which can cause isolated galaxies to become warped. The circular motion of matter in such disks will manifest itself in the misalignment of the apparent minor axis and the H I zero-velocity contour. Such an effect may be present in a number of recent H I surveys, although the data presently available do not allow definite conclusions. Alternative explanations of galactic warps are reviewed and their relation to the present proposal discussed.

Binney, J.

Some consequences of a liquid water saturated regolith in early Martian history

Flooding of low-lying areas of the Martian regolith may have occurred early in the planet's history when a comparatively dense primitive atmosphere existed. If this model is valid, the following are some pedogenic and mineralogical consequences to be expected. Fluctuation of the water table in response to any seasonal or longer term causes would have resulted in precipitation of ferric oxyhydroxides with the development of a vesicular duricrust (or hardpan). Disruption of such a crust by scarp undercutting or frost heaving accompanied by wind deflation of fines could account for the boulders visible on Utopia Planitia in the vicinity of the second Viking lander site. Laboratory and field evidence on earth suggests that under weakly oxidizing conditions lepidocrocite (rather than goethite) would have preferentially formed in the Martian regolith from the weathering of ferrous silicates, accompanied by montmorillonite, nontronite, and cronstedtite. Maghemite may have formed as a low-temperature dehydrate of lepidocrocite or directly from ferrous precursors.

Fuller, A. O.

The performance of primary Cs beam clocks using quadrupole and hexapole deflection systems. Consequences for time keeping

Since 1978 the time-and-frequency standard CS1 of the Physikalisch-Technische Bundesanstalt (PTB) has operated continuously as a 'primary clock'. Its uncertainty (7.1 to the negative 15th power) is considerably smaller than that of the other existing primary standards. The CS1 is equipped with a combination of quadrupole and hexapole magnets and uses a longitudinal C-field. Consequences of utilizing primary clocks of this quality for the generation of the International Atomic Time Scale TAI are discussed.

Becker, G.

Astrophysical consequences of a violation of the strong equivalence principle

The consequences of a supposed violation of the strong equivalence principle (SEP) for photons are analyzed theoretically and investigated using published observational data on the age of stars and globular clusters, the past temperature of the earth, the 3-K black-body radiation, and big-bang nucleosynthesis. It is shown that the photon number is unaffected by an SEP violation, which influences only massive particles. The observational data are found to be compatible with an SEP violation of the order of the Hubble constant during the matter-dominated era, while not demanding such a violation. More direct-measurement studies, based on data such as those from the Viking program, are proposed.

Canuto, V. M.

Geophysical consequences of phanerozoic and Archean crustal evolution: Evidence from crustal cross-sections

Geophysical properties of continental crust depend on the nature of crustal evolution. This is well illustrated by examination of two crustal cross-sections (1), the combined Ivrea-Verbano zone (IVZ) and Strona-Ceneri zone (SCZ) of northern Italy and the Pikwitonei granulite belt (PGB) and Cross Lake subprovince (CLS) of Manitoba. These two cross-sections are of particular interest because the IVZ and SCZ developed during Phanerozoic time whereas the PGB-CLS is an example of Archean crustal evolution. Consequently, each cross-section is geologically distinctive and, thus, exhibits very different geophysical properties such as density, seismic velocity, heat production, and magnetism. Results of geological investigations of each area are given.

Fountain, D. M.

Climatic consequences of very high CO2 levels in Earth's early atmosphere

Earth has approximately 60 bars of carbon dioxide tied up in carbonate rocks, or roughly 2/3 the amount of CO2 of Venus' atmosphere. Two different lines of evidence, one based on thermodynamics and the other on geochemical cycles, indicate that a substantial fraction of this CO2 may have resulted in the atmosphere during the first few hundred million years of the Earth's history. A natural question which arises concerning this hypothesis is whether this would have resulted in a runaway greenhouse affect. One-dimensional radiative/convective model calculations show that the surface temperature of a hypothetical primitive atmosphere containing 20 bars of CO2 would have been less than 100C and no runaway greenhouse should have occurred. The climatic stability of the early atmosphere is a consequence of three factors: (1) reduced solar luminosity at that time; (2) an increase in planetary albedo caused by Rayleigh scattering by CO2; and (3) the stabilizing effects of moist convection. The latter two factors are sufficient to prevent a CO2-induced runaway greenhouse on the present Earth and for CO2 levels up to 100 bars. It is determined whether a runaway greenhouse could have occurred during the latter stages of the accretion process and, if so, whether it would have collapsed once the influx of material slowed down.

Kasting, J. F.

Primordial magmaspheres and their lasting consequences

The lunar magmasphere is a useful but potentially misleading analog for the earliest evolution of other planetary objects. A significant fraction of the lunar magmasphere became a crust rich in buoyant cumulus plagioclase. Another significant fraction became a series of ultramafic cumulates (the mare basalt sources) complementary to the anorthosite. These events predetermined all subsequent lunar evolution. Empirically, the Moon was big enough to produce a magmasphere. Beyond a depth limit of roughly 200 km, nearly independent of the size of the planet, the remainder of the magmasphere will probably at all times be a single convective, and therefore essentially non-differentiating layer. The fraction of the mantle contained in the outer 200 km is of course inversely related to planet size. Compared to the Moon the Earth's mantle comprises a volume of 40 x greater and a pressure range 30 x greater. Steeper dP/dZ, favoring garnets and pyroxenes, also works to dampen differentiation in larger planets. One long term consequence of the Earth's magmasphere was probably a depletion of H2O in much of the mantle. Because water is a flux for mantle convection, anhydrous parts of the mantle probably had anomalously thick lithospheres and hot asthenospheres.

Warren, P. H.

General consequences of the violated Feynman scaling

The problem of scaling of the hadronic production cross sections represents an outstanding question in high energy physics especially for interpretation of cosmic ray data. A comprehensive analysis of the accelerator data leads to the conclusion of the existence of breaked Feynman scaling. It was proposed that the Lorentz invariant inclusive cross sections for secondaries of a given type approaches constant in respect to a breaked scaling variable x sub s. Thus, the differential cross sections measured in accelerator energy can be extrapolated to higher cosmic ray energies. This assumption leads to some important consequences. The distribution of secondary multiplicity that follows from the violated Feynman scaling using a similar method of Koba et al is discussed.

Kamberov, G.

Causes and consequences of reduced blood volume in space flight - A multi-discipline modeling study

A group of mathematical models of various physiological systems have been developed and applied to studying problems associated with adaptation to weightlessness. One biomedical issue which could be addressed by at least three of these models from varying perspectives was the reduction in blood volume that universally occurs in astronauts. Accordingly, models of fluid-electrolyte, erythropoiesis, and cardiovascular regulation were employed to study the causes and consequences of blood volume loss during space flight. This analysis confirms the notion that alterations of blood volume are central to an understanding of adaptation to prolonged space flight. More importantly, the modeling studies resulted in specific hypotheses accounting for plasma volume and red cell mass losses and testable predictions concerning the behavior of the circulatory system.

Leonard, J. I.

Climatic consequences of very high CO2 levels in Earth's early atmosphere

Earth has approximately 60 bars of carbon dioxide tied up in carbonate rocks, or roughly 2/3 the amount of CO2 of the atmosphere of Venus. Two different lines of evidence, one based on thermodynamics and the other on geochemical cycles, indicate that a substantial fraction of thes CO2 may have resided in the atmosphere during the first few hundred million years of the Earth's history. A natural question which arises is whether this much CO2 would have resulted in a runaway greenhouse effect. One dimensional radiative/convective model calculations presented showed that the surface temperature of a hypothetical primitive atmosphere containing 20 bars of CO2 was less than 100 C; thus no runaway greenhouse effect would have occurred. The climatic stability of the early atmosphere is a consequence of three factors: reduced solar luminosity at that time, an increase in planetary albedo caused by Rayleigh scattering by CO2, and the stabilizing effects of a moist convection. The latter two factors are sufficient to prevent a CO2 induced runaway greenhouse effect on the present Earth as well, for CO2 levels up to 100 bars. Further studies are being undertaken to determine whether a runaway greenhouse effect could have occurred during the latter stages of the accretion process and, if so, whether it would have collapsed one the influx of material slowed down.

Katsing, J. F.