Bimodal-cavity measurement of the microwave Faraday effect in a gaseous magnetoplasma Technical report no. 2
Cavity resonance measurement of Faraday rotation of microwaves in gaseous magnetoplasma
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Experimental evolution of an earth-storable bimodal rocket engine.
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Dodge, C. H.↗
Powder compaction in systems of bimodal distribution
The compaction of mixtures involving different particle sizes is discussed. The various stages of the compaction process include the rearrangement of particles, the filling of the interstices of the large particles by the smaller ones, and the change in particle size and shape upon further densification through the application of pressure. Experimental approaches and equipment used for compacting material are discussed together with the theoretical relations of the compacting process.
Chattopadhyay, A. K.↗
A bimodal search strategy for SETI
The search strategy and resultant observational plan which was developed to carry out a comprehensive Search for Extraterrestrial Intelligence (SETI) over that portion of the electromagnetic spectrum known as the terrestrial microwave window is described. The limiting sensitivity achieved was parameterized and calculated for Deep Space Network antennas as well as several radio astronomy observatories. A brief description of the instrumentation to be employed in the search and the classes of signals to be looked for is given. One observational goal is to survey the entire sky over a wide range of frequency to a relatively constant flux level. This survey ensures that all potential life sites are observed to some limiting equivalent isotropic radiated power depending upon their distance. A second goal is to survey a set of potential transmission sites selected a priori to be especially promising, achieving very high sensitivity over a smaller range of frequency.
Gulkis, S.↗
Einstein imaging observations of clusters with a bimodal mass distribution
Einstein imaging observations of four X-ray clusters of galaxies characterized by a double X-ray surface brightness and thus mass distribution are presented. The clusters A98, A115, A1750 and SC 0627-54 were found to exhibit two enhancements in their X-ray surface brightness distributions in observations made with the Einstein Imaging Proportional Counter. Calculations of the probability that the clusters represent chance superpositions indicate that the double clusters are physically associated. The radial distributions of the components are inconsistent with those of single point sources, and have been used to derive cluster luminosities which are typical of rich clusters. Masses of the subclusters are also found to be typical of bound and virialized clusters with gas contributing 10%. Within the framework of the hierarchical theory of galactic clustering, the double clusters are suggested to represent an intermediate evolutionary stage before the merger of subclusters into a relaxed Coma-type cluster.
Forman, W.↗
Three rich clusters of galaxies with bimodal or clumpy X-ray morphologies
X-ray images of the rich clusters of galaxies A1560, A2356, and A2384 show that the individual X-ray features correspond to hot gas of between one and 10 billion solar masses. These results are consistent with the formation of clusters by subcluster coalescence and merging. Clusters can be observed in almost any stage of coalescence, and it is recommended that galaxy motions and distributions be correlated with X-ray brightness distributions.
Ulmer, M. P.↗
Geochemistry and tectonic affinities of a Proterozoic bimodal igneous suite, west Texas
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Rudnick, R. L.↗
Direct evidence for two-stage (bimodal) acceleration of ionospheric ions
Energetic ion composition spectrometer data gathered on hybrid conical ion distributions by the Dynamics Explorer 1 in the topside ionosphere are reported. The observed ion distributions were field-aligned and upward flowing, with energies up to 5 keV. Increases in ion energy were accompanied by a departure from field-alignment and a cone patterned upward flow, with the apex in the auroral field lines and the cone angle widening upward as the energy increased. Both transverse and parallel accelerations were imparted to the ions, with the transverse heating occurring in a 5000 km extent region centered at 18,000 km altitude. A bi-Maxwellian distribution, a temperature of 1.2 keV and a 260 eV parallel temperature were found at the top of the region.
Klumpar, D. M.↗
Velocity filter mechanism for ion bowl disributions (Bimodal conics)
The 'bowl-shaped' ion distributions in the high altitude auroral region observed by Klumpar et al. (1984) were originally interpreted as being due to a two-stage acceleration involving transverse ion heating and upward-aligned electric field acceleration. In this paper, it is shown that qualitatively similar bowl-shaped distributions can also be formed by transverse heating in a region of finite horizontal extent, followed by essentially adiabatic convective flow to the observation location. The latter stage contributes a velocity-filtering effect which produces some characteristics of the distributions observed. It is suggested it may be possible to use ion species observations to distinguish the mechanism proposed by Klumpar et al. from the alternative mechanism outlined in the present study.
Horwitz, J. L.↗
Bimodality of the solar cycle
An alternative characterization of the solar cycle is offered that is consistent with the sunspot data for cycles 1-20 (1775-1976) but suggests a different physical interpretation. For sunspot cycles 1-20, all cycles occurred in strings (two to six cycles in length) during which the period remained longer or shorter than the sample mean period. These strings have coincided with long-term trends of growth or decay in the amplitude of the cycle. In six out of six cases, the period of the cycle has switched from long to short (or the reverse) in coincidence with the turning points in the long-term trend. This suggests that the solar dynamo has two modes with different mean periods. In the short-period mode, the amplitude of the cycle grows; in the long-period mode, the amplitude decays. The transition between modes has occurred at irregular intervals. A persistence of the long-period mode would eventually produce a grand minimum such as the Maunder minimum; a persistence of the short-period mode would produce a grand maximum. Unless the present interval between transitions turns out to be shorter than any previously observed interval, the present cycle (cycle 21) is part of a long-period, decaying trend and will be of longer-than-average duration (more than 133 months).
Rabin, D.↗
Bimodal quasi-oscillatory and spectral behavior in Sco X-1
X-ray observations were made to follow up the discovery of quasi-periodic oscillations (QPO) in Sco X-1. The QPO is observed in the quiescent state, and between flares in the active state. When the source is quiescent, the QPO frequency is 6 Hz and anticorrelated with intensity; in the active state, the frequency ranges from 10 to 20 Hz and is strongly correlated with intensity. At high intensities the QPO dissolves into continuum noise. The QPO rms amplitude decreases with count rate, and increases with photon energy. There are two modes of spectral behavior, with a one-to-one correspondence to the two modes of QPO: the spectral hardness ratio varies more steeply with intensity when the source shows 6 Hz QPO, than for 10 to 20 Hz QPO. Transitions between QPO modes, which occur when the flux is at its lowest levels, correspond to transitions between hardness ratio modes. The QPO frequency changes continuously through the transitions, which last a few hundred seconds.
Priedhorsky, W.↗
Bimodal star formation - Constraints from galaxy colors at high redshift
The possibility that at early epochs the light from elliptical galaxies is dominated by stars with an initial mass function (IMF) which is deficient in low-mass stars, relative to the solar neighborhood is investigated. V-R colors for the optical counterparts of 3CR radio sources offer the most severe constraints on the models. Reasonable fits are obtained to both the blue, high-redshift colors and the redder, low-redshift colors with a model galaxy which forms with initially equal star formation rates in each of two IMF modes: one lacking low-mass stars, and one with stars of all masses. The net effect is that the time-integrated IMF has twice as many high-mass stars as the solar neighborhood IMF, relative to low mass stars. A conventional solar neighborhood IMF does not simultaneously account for both the range in colors at high redshift and the redness of nearby ellipticals, with any single star formation epoch. Models with a standard IMF require half the stellar population to be formed in a burst at low redshift z of about 1.
Wyse, Rosemary F. G.↗
Estimating the cost of mental loading in a bimodal divided-attention task: Combining reaction time, heart-rate variability and signal-detection theory
Multiple approaches are necessary for understanding and measuring workload. In particular, physiological systems identifiable by employing cardiac measures are related to cognitive systems. One issue of debate in measuring cardiac output is the grain of analysis used in recording and summarizing data. Various experiments are reviewed, the majority of which were directed at supporting or contradicting Lacey's intake-rejection hypothesis. Two of the experiments observed heart rate in operational environments and found virtually no changes associated with mental load. The major problems facing researchers using heart rate variability, or sinus arrhthmia, as a dependent measure have been associated with valid and sensitive scoring and preventing contamination of observed results by influences unrelated to cognition. Spectral analysis of heart rate variability offers two useful procedures: analysis from the time domain and analysis from the frequency domain. Most recently, data have been collected in a divided attention experiment, the performance measures and cardiac measures of which are detailed.
Casper, Patricia A.↗
Bimodal abundances in the energetic particles of solar and interplanetary origin
This letter reports the first results from an examination of the daily-averaged abundances of the elements from H through Fe as well as electrons and isotopes of He in energetic particles observed in interplanetary space by the ISEE 3 spacecraft over an 8.5 yr period. The abundances of heavy elements such as Fe/O show, for the first time, clear evidence of the presence of two distinct populations of particles. Earlier observations could be interpreted as extreme variations within a single population. The population with enhanced Fe/O shows correlated enhancements in He-3/He-4, p/e, and He/H. This population is consistent with material that has been processed to high temperatures in the impulsively heated regions of solar flares. The second population, with more normal abundances, is probably accelerated from ambient material by coronal and interplanetary shocks.
Reames, Donald V.↗
A bimodal model for the galaxy luminosity function
The galaxy luminosity function in the Virgo cluster has been recently found to show a clear separation between bright galaxies and dwarf galaxies. Here, consideration is given to the effect on the luminosity function of galaxy binding energy which allows gas to be retained and star formation to proceed over about 1 Gyr in massive galaxies, but implies wind-driven mass loss and inefficient star formation in dwarf galaxies.
Schaeffer, R.↗
Bimodality and the Hale cycle
Evidence is provided of a modulation of between 20 and 24 yr for the Hale cycle, and comparison of consecutive pairs of cycles strongly suggests that even-numbered cycles are preferentially paired with odd-numbered following cycles. The results indicate that cycles 22 and 23 form a new cyle pair. The sum of monthly mean sunspot numbers over consecutively paired sunspot cycles for Hale cycle 12 is found to be about 19,100 + or - 3000.
Wilson, Robert M.↗
A signal detection analysis of bimodal attention: Support for response interference
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Casper, Patricia Ann↗
Optimum single modal and bimodal buckling design of symmetric laminates
Variational calculus is used to determine the design that maximizes the resistance of classical symmetric laminates against buckling. The orientations of the constituent orthotropic laminae with respect to the principal axes of the laminate are the design variables. It is shown that the optimal design may not be a point of analyticity of the buckling load. Local analytic extrema are obtained from the design derivatives of the buckling load. Nonanalytic extrema occur whenever the buckling load is a repeated eigenvalue. A novel approach, using a directional design derivative, is employed to determine nonanalytic extrema. Specific examples are presented for biaxial buckling for several different boundary conditions.
Qian, B.↗