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Enhancement of the auditory vertex potentials with selective attention to dichotically presented tone pips was found to be critically sensitive to the range of inter-stimulus intervals in use. Only at the shortest intervals was a clear-cut enhancement of the latency component to stimuli observed for the attended ear.
Boulder 1 at Station 2 is one of three boulders sampled by Apollo 17 at the base of the South Massif, which rises 2.3 km above the floor of a linear valley interpreted as a graben formed by deformation related to the southern Serenitatis impact. The boulders probably rolled from the upper part of the massif after emplacement of the light mantle. The massif exposures are suggested to represent the upper part of thick ejecta deposited by the southern Serenitatis impact near the rim of the transient cavity. The ring structure of the southern Serenitatis basin and the radial grabens that give the massifs definition were imposed on this ejecta at a slightly later stage in the basin-forming process. There is no clear-cut compositional, textural, or photogeological evidence that Imbrium ejecta was collected at the Apollo 17 site.
It is proposed that Li-7 is produced in the Galaxy primarily by alpha-alpha collisions surrounding newly born pulsars. About 10 percent of the pulsar energy losses are converted to medium-energy alpha-particles which collide in a dominantly He nebula. The problem of the origin of lithium would be solved by the scenario, and clear-cut tests by nuclear gamma-ray astronomy are described.
The objective of the Skylab Lower Body Negative Pressure experiment was to determine the extent and the time course of changes in orthostatic tolerance during the weightlessness of space flight and to determine whether in-flight data from the experiment would be useful in predicting the postflight status of orthostatic tolerance. Compared to preflight results, lower body negative pressure produced exaggerated blood pressure and heart rate responses during the first in-flight test of the Skylab 2 crewmen and showed no clear-cut trend toward preflight levels during the 28-day flight. During the second manned mission, Skylab 3, similar exaggeration of blood pressure and heart rate responses occurred during the first in-flight test. Again no definite trend toward preflight values could be seen during the first 28 days but cardiovascular responses to lower body negative pressure appeared to become more stable by the sixth to eighth week of flight. In general, the test results in-flight served to predict quite well the orthostatic tolerance of the individual crewmen in the immediate postflight period.
The author has identified the following significant results. Level 2 forest features (softwood, hardwood, clear-cut, and water) can be classified with an overall accuracy of 71.6 percent plus or minus 6.7 percent at the 90 percent confidence level for the particular data and conditions existing at the time of the study. Signatures derived from training fields taken from only 10 percent of the site are not sufficient to adequately classify the site. The level 3 softwood age group classification appears reasonable, although no statistical evaluation was performed.
Balloon observations of the horizontal electric field, from six Canadian sites during August 2, 3, 8 and 9 of 1969, have been analyzed for coherent oscillations: right, left, and linearly polarized in the 1-16 mHz range. On any particular day there are 'calm' periods where a number of frequencies in the 1-16 mHz range exist. The length of these periods may vary from a few hours to several hours. The 'disturbed' periods can occur at any time of the day. The length of disturbed periods, number of significant frequencies in the band, and their probability of occurrence show a tendency to increase with latitude up to the auroral zone, beyond which no significant increase has been seen. The regions of the disturbed electric field sometimes cover a wide range of latitudes (greater than 10 deg) and longitudes in the auroral zone. Some of these regions are well defined and fixed in space and may remain unchanged for several hours to sometimes more than a day. For the frequency band studied, polarization of one kind (right or left) may dominate over the other for several hours after which the roles may interchange. These reversals do not show any clear-cut latitudinal dependence. Instead, there is more similarity in their behavior.
The issue of integenerational equity in the use of natural resources is discussed in the context of coal mining conversion. An attempt to determine if there is a clear-cut benefit to future generations in setting minimum coal extraction efficiency standards in mining is made. It is demonstrated that preserving fossil fuels beyond the economically efficient level is not necessarily beneficial to future generations even in terms of their own preferences. Setting fossil fuel conservation targets for intermediate products (i.e. energy) may increase the quantities of fossil fuels available to future generations and hence lower the costs, but there may be serious disadvantages to future generations as well. The use of relatively inexpensive fossil fuels in this generation may result in more infrastructure development and more knowledge production available to future generations. The value of fossil fuels versus these other endowments in the future depends on many factors which cannot possibly be evaluated at present. Since there is no idea of whether future generations are being helped or harmed, it is recommended that integenerational equity not be used as a factor in setting coal mine extraction efficiency standards, or in establishing requirements.
A synopsis of a forum addressing the use of LANDSAT data in forestry is given. Broad inventory studies, clear-cut monitoring, and insect and disease detection were among the subject areas discussed. Concerns regarding the vailability of data, cloud cover, resolution and classification accuracy, and product format were expressed by foresters.
Surface and internal lava structures can be valid indicators of lava viscosity and rheology, provided that care is taken to identify and eliminate structures which are strain-rate-dependent. Here, a spectrum of types among Hawaiian basaltic flows is found ranging from pahoehoe to a'a, that are interpreted as marking a progression in lava viscosity and a change in rheology. The most fluid type in this spectrum is normal pahoehoe that has a smooth but commonly wrinkled or folded (ropy) surface. The next type, distinctly more viscous and probably non-Newtonian in rheology, is spiny pahoehoe which is characterized by a spinose surface and an absence of ropy structures. Preliminary studies on the long lavas of Mauna Loa indicated, perhaps surprisingly, that there is no clear-cut correlation of lava length with type in this spectrum of lavas, indicating that viscosity/yield strength of the basaltic lavas per se are not the primary controls determining flow length. Flowage of the lava through lava tubes, while it may help to account for the long flow distance of some lavas, is not a generally applicable explanation for long flow length.
Nuclear track studies, uranium concentration measurements and Sm-isotope studies have been performed on both lithologies A and B of the Elephant Morraine shergottite, EETA 79001. Track studies show that EETA 79001 was a rather small object in space with a preatmospheric radius of 12 + or - 2 cm, corresponding to a preatmospheric mass of 28 + or - 13 kg. Phosphates have U concentrations ranging from 0.3 to 1.3 ppm. There are occasional phosphates with excess fission tracks, possibly produced from neutron-induced fission of U and Th, during the regolith exposure in the shergottite parent body (SPB). Sm-isotope studies, while not showing any clear-cut excess in Sm-150, make it possible to derive meaningful upper limits to thermal neutron fluences of 2 to 3 x 10 to the 15th n/sq cm, during a possible regolith irradiation. These limits are consistent with the track data and also make it possible to derive an upper limit to the neutron exposure age of EETA 79001 of 55 Myr in the SPB regolith.
A new approach is reported to the measurement of the complete polarization signature of each resolution element in an image implemented with an airborne synthetic aperture radar system. Signals recorded on one data pass from orthogonal linearly polarized antennas are utilized. The signals are combined in a data processor to synthesize any desired combination of transmit and receive polarizations. The technique permits measurement of the complex, multichannel reflectivity of a scene on a single aircraft pass and to late reprocess the data to provide multiple image maps, with each representing the backscattered energy from the scene measured with a different combination of observational transmit and recieve polarizations. The resulting polarization signature measurements indicate optimum polarizations for observations of certain classes of objects and give insight into the identification of dominant scattering mechanisms for each kind of object. The mathematical model for polarization synthesis is summarized, and some theoretical polarization measurements are illustrated for several types of targets. The overall radar system implementation is described in detail. Some analyses of data acquired on three aircraft flights are presented. The technique has been applied to mapping and differentiation of lava flows and to differentiation of forested and clear-cut areas.
Trends for 16 trace elements (Ag, As, Au, Bi, Cd, Co, Cs, Ga, In, K, Rb, Sb, Se, Te, Tl, and Zn), chosen to span a broad geochemical and thermal response range, in 44 H4-6 chondrites, differ widely from those in L4-6 chondrites. In particular, H chondrites classified as heavily shocked petrologically do not necessarily exhibit Ar-40 loss and vice versa. The clear-cut causal relationship between siderophile and mobile element loss with increasing late shock seen in L chondrites is not generally evident in the H group. H chondrite parent material experienced an early high temperature genetic episode that mobilized a substantial proportion of these trace elements so that later thermal episodes resulted in more subtle, collateral fractionations. Mildly shocked L chondrites escaped this early high temperature event, indicating that the two most numerous meteorite groups differ fundamentally in genetic history.
Astronauts report that head movements in flight tend to bring on symptoms of space motion sickness (SMS). The effects of head movements in pitch, yaw, and roll (made both with normal vision and with eyes occluded) on susceptibility to motion sickness in the zero G phase of parabolic flight maneuvers were evaluated. The findings are clear-cut: pitch head movements are most provocative, yaw least provocative, and roll intermediate. These experiments suggest that SMS is not a unique nosological entity, but is the consequence of exposure to nonterrestrial force levels. Head movements during departures in either direction from 1 G elicit symptoms.
The geomagnetic control of ionospheric D region dynamics was revealed and confirmed on the basis of radiophysical wind measurements (1978 to 1983) over East Siberia. The monthly mean parameters of the wind system are different for quiet and disturbed conditions. There is an increase in stability of the meridional wind with increasing level of geomagnetic activity. The influence of geomagnetic storms on the measured wind is considered on the basis of 31 events. There are effects on the phase of the semidiurnal tidal wind, but variations of amplitude are weak. The effect of the geomagnetic storm depends on the intensity and is more clear-cut for the A sub p is greater than 100.
Long-split spectrophotometric observations of Comet Halley on five nights at heliocentric distances of 0.90-2.21 AU are used to determine the surface brightness distribution of the coma in the strongest C2 Swan bands and the scattered light continuum. It is found that the C2 must be the product of the decay of two precursors. A clear-cut determination of the variation of the C2 band sequence flux ratios with heliocentric distance is obtained.
The use of an imaging radar polarimeter data for unsupervised classification of scattering behavior is described by comparing the polarization properties of each pixel in a image to that of simple classes of scattering such as even number of reflections, odd number of reflections, and diffuse scattering. For example, when this algorithm is applied to data acquired over the San Francisco Bay area in California, it classifies scattering by the ocean as being similar to that predicted by the class of odd number of reflections, scattering by the urban area as being similar to that predicted by the class of even number of reflections, and scattering by the Golden Gate Park as being similar to that predicted by the diffuse scattering class. It also classifies the scattering by a lighthouse in the ocean and boats on the ocean surface as being similar to that predicted by the even number of reflections class, making it easy to identify these objects against the background of the surrounding ocean. The algorithm is also applied to forested areas and shows that scattering from clear-cut areas and agricultural fields is mostly similar to that predicted by the odd number of reflections class, while the scattering from tree-covered areas generally is classified as being a mixture of pixels exhibiting the characteristics of all three classes, although each pixel is identified with only a single class.
The individual fibers of any individual muscle vary greatly in enzyme composition, a fact which is obscured when enzyme levels of a whole muscle are measured. The purpose of this study was therefore to assess the changes due to weightless on the enzyme patterns composed by the individual fibers within the flight muscles. In spite of the limitation in numbers of muscles examined, it is apparent that: (1) that the size of individual fibers (i.e., their dry weight) was reduced about a third, (2) that this loss in dry mass was accompanied by changes in the eight enzymes studied, and (3) that these changes were different for the two muscles, and different for the two enzyme groups. In the soleus muscle the absolute amounts of the three enzymes of oxidative metabolism decreased about in proportion to the dry weight loss, so that their concentration in the atrophic fibers was almost unchanged. In contrast, there was little loss among the four enzymes of glycogenolysis - glycolysis so that their concentrations were substantially increased in the atrophic fibers. In the TA muscle, these seven enzymes were affected in just the opposite direction. There appeared to be no absolute loss among the oxidative enzymes, whereas the glycogenolytic enzymes were reduced by nearly half, so that the concentrations of the first metabolic group were increased within the atrophic fibers and the concentrations of the second group were only marginally decreased. The behavior of hexokinase was exceptional in that it did not decrease in absolute terms in either type of muscle and probably increased as much as 50 percent in soleus. Thus, their was a large increase in concentration of this enzyme in the atrophied fibers of both muscles. Another clear-cut finding was the large increase in the range of activities of the glycolytic enzymes among individual fibers of TA muscles. This was due to the emergence of TA fibers with activities for enzymes of this group extending down to levels as low as those found in control soleus muscles. It would be interesting to know if this represents a transition stage, and whether with prolonged weightlessness most of the fibers would be transformed into a low glycogenolytic type.
A search for periodic variation in the production of gas and dust by Comet Halley has been performed using narrowband photometric measurements from four sites - Lowell Observatory, Mauna Kea Observatory, Perth Observatory, and Cerro Tololo Inter-American Observatory. The method of phase dispersion minimization was applied to observations made during 164 observing nights between September 1985 and June 1986. A clear-cut variation, with a period near 7.4 days, was present throughout the postperihelion window. Less conclusive evidence of a similar period has been found in the pre-perihelion data. No indication of a shorter period or of strong sporadic activity exists in the data. The observations require that Halley's nucleus returns to essentially the same orientation with respect to the sun approximately every 7.4 days except for longer-timescale seasonal evolution. This fact precludes certain proposed models of nuclear motion.