Showing papers by "California Institute of Technology published in 1974"
TL;DR: In this article, Spark shadow pictures and measurements of density fluctuations suggest that turbulent mixing and entrainment is a process of entanglement on the scale of the large structures; some statistical properties of the latter are used to obtain an estimate of entrainedment rates, and large changes of the density ratio across the mixing layer were found to have a relatively small effect on the spreading angle.
Abstract: Plane turbulent mixing between two streams of different gases (especially nitrogen and helium) was studied in a novel apparatus Spark shadow pictures showed that, for all ratios of densities in the two streams, the mixing layer is dominated by large coherent structures High-speed movies showed that these convect at nearly constant speed, and increase their size and spacing discontinuously by amalgamation with neighbouring ones The pictures and measurements of density fluctuations suggest that turbulent mixing and entrainment is a process of entanglement on the scale of the large structures; some statistical properties of the latter are used to obtain an estimate of entrainment rates Large changes of the density ratio across the mixing layer were found to have a relatively small effect on the spreading angle; it is concluded that the strong effects, which are observed when one stream is supersonic, are due to compressibility effects, not density effects, as has been generally supposed
3,339 citations
TL;DR: In this paper, an indirect method of estimating the solubility parameter of high molecular weight polymers is proposed, which is based on group additive constants, but is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of structural formula of the compound.
Abstract: Development of an indirect method of estimating the solubility parameter of high molecular weight polymers. The proposed method of estimating the solubility parameter, like Small's method, is based on group additive constants, but is believed to be superior to Small's method for two reasons: (1) the contribution of a much larger number of functional groups have been evaluated, and (2) the method requires only a knowledge of structural formula of the compound.
1,590 citations
TL;DR: The salivary glands and other tissues from Drosophila melanogaster were dissected at various times throughout the prepupal period, as well as after heat shocks and ecdysterone treatments, and the proteins labelled by incubating the isolated tissues with [35S]methionine were separated by electrophoresis on sodium dodecyl sulphate-polyacrylamide gel.
1,154 citations
TL;DR: A theory which holds that information is normally stored within a specialized memory rather than the system immediately responsible for the performance of behavior is advanced and the effects of hippocampal ablation are explained in terms of the elimination of such transfer.
922 citations
TL;DR: In this article, the Segre-Silberberg effect of inertia-induced lateral migration of a neutrally buoyant rigid sphere in a Newtonian fluid is studied theoretically for simple shear flow and for two-dimensional Poiseuille flow.
Abstract: The familiar Segre-Silberberg effect of inertia-induced lateral migration of a neutrally buoyant rigid sphere in a Newtonian fluid is studied theoretically for simple shear flow and for two-dimensional Poiseuille flow. It is shown that the spheres reach a stable lateral equilibrium position independent of the initial position of release. For simple shear flow, this position is midway between the walls, whereas for Poiseuille flow, it is 0·6 of the channel half-width from the centre-line. Particle trajectories are calculated in both cases and compared with available experimental data. Implications for the measurement of the rheological properties of a dilute suspension of spheres are discussed.
790 citations
TL;DR: In this article, a self-consistent model of instantaneous relative motions for eleven major plates is presented, assuming that the lithospheric plates to be rigid, and the authors systematically invert 68 spreading rates, 62 fracture zones trends and 10^6 earthquake slip vectors simultaneously to obtain a self consistent model.
Abstract: Assuming lithospheric plates to be rigid, we systematically invert 68 spreading rates, 62 fracture zones trends and 10^6 earthquake slip vectors simultaneously to obtain a self-consistent model of instantaneous relative motions for eleven major plates. The inverse problem is linearized and solved iteratively by a maximum likelihood procedure. Because the uncertainties in the data are small, Gaussian statistics are shown to be adequate. The use of a linear theory permits (1) the calculation of the uncertainties in the various angular velocity vectors caused by uncertainties in the data, and (2) quantitative examination of the distribution of information within the data set.
The existence of a self-consistent model satisfying all the data is strong justification of the rigid plate assumption. Slow movement between North and South America is shown to be resolvable.
We then invert the trends of 20 linear island chains and aseismic ridges under the assumptions that they represent the directions of plate motions over a set of hot spots fixed with respect to each other. We conclude that these hot spots have had no significant relative motions in the last 10 My.
746 citations
TL;DR: In this paper, it was shown that highland samples from widely separated areas bear the imprint of an event or series of events in a narrow time interval which can be identified with a cataclysmic impacting rate of the moon at about 3.9 aeons.
677 citations
TL;DR: In this paper, the post-midnight chorus was detected in the midnight sector of the magnetosphere in conjunction with magnetospheric substorms and the characteristics of these emissions such as their frequency time structure, emission frequency with respect to the local equatorial electron gyrofrequency, intensity-time variation, and the average intensity were investigated.
Abstract: The ELF emissions were detected in the midnight sector of the magnetosphere in conjunction with magnetospheric substorms. The emissions were observed at local midnight and early morning hours and are accordingly called 'post-midnight chorus.' The characteristics of these emissions such as their frequency time structure, emission frequency with respect to the local equatorial electron gyrofrequency, intensity-time variation, and the average intensity were investigated. The occurrence of the chorus in the nightside magnetosphere was investigated as a function of local time, L shell, magnetic latitude, and substorm activity, and the results of this analysis are presented. Specific features of postmidnight chorus are discussed in the context of possible wave-particle interactions occurring during magnetospheric substorms.
626 citations
TL;DR: In this article, it was shown that in the limit of zero slope (with gvs2α′ held fixed) one obtains the Einstein theory of gravitation accompanied by a massless scalar field.
578 citations
TL;DR: In this article, an alternative criterion for decision-making under uncertainty, minimax regret, specifies voting under quite general conditions, and both two and three candidate plurality elections are considered.
Abstract: Various analysts have noted that the decision to vote in mass elections is difficult to justify from the standpoint of an expected utility maximization model. Put simply, the probability that a citizen's vote will affect the outcome is so small that the expected gains from voting are outweighed by the costs in time and effort. Such analyses treat rational behavior as synonymous with expected utility maximization. In this paper we show that an alternative criterion for decision making under uncertainty, minimax regret, specifies voting under quite general conditions. Both two and three candidate plurality elections are considered. Interestingly, a minimax regret decision maker never votes for his second choice in a three candidate election, whereas expected utility maximizers clearly may. Thus, the model proposed has implications for candidate choice as well as turnout.
549 citations
TL;DR: An empirical result showing a simple constant relationship between thevolume flow rate and the double-slit centerline velocity makes the volume flow rate measurement by this technique simple and implies that the actual velocity profiles do not change significantly from a parabolic shape over a wide range of U hematocrit, and tube diameter.
15 Feb 1974
TL;DR: In this article, the relation between the dynamical state equations in explicit terms and servoing the manipulator is briefly discussed in the framework of state variable feedback control which also forms the basis of adaptive manipulator control.
Abstract: Variations in total inertia and gravity loads at the joint outputs are treated along with the relative importance of gravity and acceleration-generated reaction torques or forces versus inertia torques or forces. The relation between the dynamical state equations in explicit terms and servoing the manipulator is briefly discussed in the framework of state variable feedback control which also forms the basis of adaptive manipulator control. Exact state equations were determined for total inertia and gravity loads at the joint outputs as a function of joint variables, using the constant inertial and geometric parameters of the individual links defined in the respective link coordinate frames. The range of maximum variations in total inertia and gravity loads at the joint outputs was calculated for both no load and load in the hand. The main result is the construction of a set of greatly simplified state equations which describe the total inertia and gravity load variations at the output of the six joints with an average error of less than 5%.
TL;DR: The sequence relations between some bacterial F-prime factors in Escherichia coli have been determined by observing the pattern of duplex and single-stranded regions in heteroduplexes consisting of one strand from one episome and the complementary strand from another.
TL;DR: In this article, a long-period strain seismogram recorded at Pasadena is used to determine the focal process of the 1960 Chilean earthquake, and a simple dislocation model is proposed to explain this precursory displacement.
01 Sep 1974
TL;DR: In this article, the authors derived separable equations describing perturbations of a Kerr black hole, which can be used to study black-hole processes involving scalar, electromagnetic, neutrino or gravitational fields.
Abstract: Decoupled, separable equations describing perturbations of a Kerr black hole are derived. These equations can be used to study black-hole processes involving scalar, electromagnetic, neutrino or gravitational fields. A number of astrophysical applications are made: Misner's idea that gravitational synchrotron radiation might explain Weber's observations is shown to be untenable; rotating black holes are shown to be stable against small perturbations; energy amplification by "superradiant scattering" of waves off a rotating black hole is computed; the "spin down" (loss of angular momentum) of a rotating black hole caused by a stationary non-axisymmetric perturbation is calculated.
TL;DR: In this paper, a sum rule for the asymmetry in deepinelastic scattering of polarized electrons from polarized protons was derived from the quark light-cone algebra and the assumption that strange quarks do not contribute to the asymmetric scattering.
Abstract: A sum rule is derived for the asymmetry in deep-inelastic scattering of polarized electrons from polarized protons: ∫01dξgep(ξ)≈0.15gA. The result follows from the quark light-cone algebra and the assumption that strange quarks do not contribute to the asymmetry. The latter is justified by conventional parton-model arguments.
TL;DR: In this article, the image system for the fundamental singularities of viscous (including potential) flow is obtained in the vicinity of an infinite stationary no-slip plane boundary, where the authors obtain a far field of O(r−2) for force or rotational components parallel to the wall, whereas normal components are of higher order O(ρ−3).
Abstract: The image system for the fundamental singularities of viscous (including potential) flow are obtained in the vicinity of an infinite stationary no-slip plane boundary. The image system for a: stokeslet, the fundamental singularity of Stokes flow; rotlet (also called a stresslet), the fundamental singularity of rotational motion; a source, the fundamental singularity of potential flow and also the image system for a source-doublet are discussed in terms of illustrative diagrams. Their far-fields are obtained and interpreted in terms of singularities. Both the stokeslet and rotlet have similar far field characteristics: for force or rotational components parallel to the wall a far-field of a stresslet typeO(r
−2) is obtained, whereas normal components are of higher orderO(r
−3).
TL;DR: In this article, the authors describe variations in the solar insolation on Mars that result from oscillations of the orbital eccentricity and the obliquity of the planet, and a detailed account of the time evolution of these quantities is given.
Abstract: Description of variations in the solar insolation on Mars that result from oscillations of the orbital eccentricity and the obliquity of the planet. Changes in the eccentricity and obliquity are produced by gravitation perturbations from the sun and the other planets, and a detailed account of the time evolution of these quantities is given. Particular attention is paid to the obliquity oscillations, which exert a strong influence on the climate of Mars. Changes in the earth's obliquity are also calculated, and its behavior is contrasted with that of Mars. Although the eccentricity produces important north-south seasonal asymmetries, a change in the obliquity causes a strong latitudinal redistribution of the solar insolation. Especially noteworthy is the fact that the yearly insolation at the poles of Mars varies by over 100% between the extremes of the obliquity range.
TL;DR: In this paper, it has been argued that modernization promotes potentially disintegrative forces in developing areas, and in particular, often gives rise to powerful ethnic groupings (see Geertz, 1963; Melson and Wolpe, 1970; Huntington, 1968).
Abstract: It has been argued that modernization promotes potentially disintegrative forces in developing areas, and in particular, often gives rise to powerful ethnic groupings (for example, see Geertz, 1963; Melson and Wolpe, 1970; Huntington, 1968). In this article, we elaborate this hypothesis in the context of the developing nations of black Africa. We note that important competition can and do covary in contemporary Africa (Morrison and Stevenson, 1972). And we attempt to explain why this should be so.
01 Jun 1974
TL;DR: In this paper, it has been suggested that this horizon-glow (HG) is sunlight, which is forward-scattered by dust grains present in a tenuous cloud formed temporarily (≲ 3 h duration) just above sharp sunlight/shadow boundaries in the terminator zone.
Abstract: Each of the Surveyor 7, 6, and 5 spacecraft observed a line of light along its western lunar horizon following local sunset. It has been suggested that this horizon-glow (HG) is sunlight, which is forward-scattered by dust grains (~ 10µ in diam, ~ 50 grains cm−2) present in a tenuous cloud formed temporarily (≲ 3 h duration) just above sharp sunlight/shadow boundaries in the terminator zone. Electrically charged grains could be levitated into the cloud by intense electrostatic fields (> 500 V cm−1) extending across the sunlight/shadow boundaries. Detailed analysis of the HG absolute luminance, temporal decay, and morphology confirm the cloud model. The levitation mechanism must eject 107 more particles per unit time into the cloud than could micro meteorites. Electrostatic transport is probably the dominant local transport mechanism of lunar surface fines.
TL;DR: In this article, the Pioneer 10 vector helium magnetometer was used along with models of the intrinsic magnetic field of Jupiter and its magnetosphere, and a model of the Jovian magnetosphere was presented in which the essential feature is an eastward current sheet that forms an annulus with Jupiter at the center.
Abstract: Data obtained by the Pioneer 10 vector helium magnetometer are presented along with models of the intrinsic magnetic field of Jupiter and its magnetosphere. Data acquired between 2.84 and 6.0 Jupiter radii, where the intensity of the planetary field ranged between 1900 and 18,400 gamma, were used to develop a six-parameter eccentric dipole model of the field. The dipole so derived has a moment of 4.0 G (R sub J) cubed and a tilt angle with respect to Jupiter's rotation axis of 11 deg. A model of the Jovian magnetosphere is presented in which the essential feature is an eastward current sheet that forms an annulus with Jupiter at the center. At large distances from the planet the current sheet is nearly parallel to Jupiter's equator but, in general, does not lie in it. The current sheet is warped, so that it is above the equator on one side and below it on the other. The current sheet rotates with the planet, more or less like a rigid body, this behavior causes an apparent up and down motion and periodic crossings of the current sheet by Pioneer.
TL;DR: In this paper, the authors considered reservoir properties as continuous functions of position rather than as uniform in a certain number of zones and proposed an optimal control approach for history-matching problems.
Abstract: History-matching problems, in which reservoir parameters arc to be estimated from well pressure data, are formulated as optimal control problems. The necessary conditions for optimality lead naturally to gradient optimization methods for determining the optimal parameter estimates. The key feature of the approach is that reservoir properties are considered as continuous functions
of position rather than as uniform in a certain number of zones. The optimal control approach is illustrated on a hypothetical reservoir and on an actual Saudi Arabian reservoir, both characterized by single-phase flow. A significant saving in computing time over conventional constant-zone gradient optimization methods is demonstrated.
TL;DR: Stroud et al. as mentioned in this paper reported the progress of analysis from the low-resolution (5 A) model, which shows the general molecular architecture, through high-resolution density maps, from which a model of the enzyme was built.
TL;DR: Using normal diploid WI-38 cells, the changes in cell morphology during adhesion and flattening on to the glass surface in vitro were studied with a scanning electron microscope to find a probable mechanism responsible for the morphological events during cell adhesion.
TL;DR: In this paper, the Korteweg-de Vries (KdV) equation is tested experimentally as a model for moderate amplitude waves propagating in one direction in relatively shallow water of uniform depth.
Abstract: The Korteweg-de Vries (KdV) equation is tested experimentally as a model for moderate amplitude waves propagating in one direction in relatively shallow water of uniform depth. For a wide range of initial data, comparisons are made between the asymptotic wave forms observed and those predicted by the theory in terms of the number of solitons that evolve, the amplitude of the leading soliton, the asymptotic shape of the wave and other qualitative features. The KdV equation is found to predict accurately the number of evolving solitons and their shapes for initial data whose asymptotic characteristics develop in the test section of the wave tank. The accuracy of the leading-soliton amplitudes computed by the KdV equation could not be conclusively tested owing to the viscous decay of the measured wave amplitudes; however, a procedure is presented for estimating the decay in amplitude of the leading wave. Computations suggest that the KdV equation predicts the amplitude of the leading soliton to within the expected error due to viscosity (12%) when the non-decayed amplitudes are less than about a quarter of the water depth. Indeed, agreement to within about 20% is observed over the entire range of experiments examined, including those with initial data for which the non-decayed amplitudes of the leading soliton exceed half the fluid depth.
TL;DR: The available compositional data support Cameron's hypothesis of a dense, convective solar nebula, opaque to solar radiation, with an adiabatic temperature-pressure profile.
Abstract: The available compositional data on planets and satellites can be used to place stringent limits on the thermal environment in the solar nebula. The densities of the terrestrial planets, Ceres and Vesta, the Galilean satellites, and Titan; the atmospheric compositions of several of these bodies; and geochemical and geophysical data on the earth combine to define a strong dependence of formation temperature on heliocentric distance. The pressure and temperature dependences of the condensation process are separable in the sense that the variation of the deduced formation temperatures with heliocentric distance is insensitive to even very diverse assumptions regarding the pressure profile in the nebula. It is impossible to reconcile the available compositional data with any model in which the formation temperatures of these bodies are determined by radiative equilibrium with the sun, regardless of the sun's luminosity. Rather, the data support Cameron's hypothesis of a dense, convective solar nebula, opaque to solar radiation, with an adiabatic temperature-pressure profile.
DOI•
01 Jan 1974TL;DR: In this article, the authors derived separable equations describing perturbations of a Kerr black hole, which can be used to study black-hole processes involving scalar, electromagnetic, neutrino or gravitational fields.
Abstract: Decoupled, separable equations describing perturbations of a Kerr black hole are derived. These equations can be used to study black-hole processes involving scalar, electromagnetic, neutrino or gravitational fields. A number of astrophysical applications are made: Misner's idea that gravitational synchrotron radiation might explain Weber's observations is shown to be untenable; rotating black holes are shown to be stable against small perturbations; energy amplification by "superradiant scattering" of waves off a rotating black hole is computed; the "spin down" (loss of angular momentum) of a rotating black hole caused by a stationary non-axisymmetric perturbation is calculated.
01 Jan 1974
TL;DR: In this paper, a theoretical analysis is presented to describe the deposition of Brownian particles which interact with collectors through an attractive-repulsive potential, when the interactions are confined sufficiently near the collector surface, it is shown that the process is equivalent to ordinary convective diffusion in the bulk with a first-order surface reaction at the collector.
Abstract: A theoretical analysis is presented to describe the deposition of Brownian particles which interact with collectors through an attractive-repulsive potential. When the interactions are confined sufficiently near the collector surface, it is shown that the process is equivalent to ordinary convective diffusion in the bulk with a first-order surface reaction at the collector; a formula for the surface reaction coefficient is derived in terms of the net interaction potential. Large Peclet solutions appropriate to hydrocolloid collection by spheres and cylinders with first-order surface reaction are obtained and available solutions are discussed. The ratio of overall deposition to deposition under diffusion control proves to be a function of a single dimensionless parameter. At extreme values of this parameter collection becomes surface reaction controlled or diffusion controlled.
TL;DR: The hypothesis presented here suggests that simple derivatives of metabolites, including neurotransmitters and cyclic nucleotides, are linked together as regulatory molecules throughout the eukaryotes and are suggested to have a more general role in information transmission in eucaryotes than is generally accepted.
Abstract: The hypothesis that physiological and developmental regulatory mechanisms are similar has been presented. Well-known developmental systems chosen illustrate the capability of the model to suggest a simple mechanism underlying the effects on development of a diverse group of chemicals. This hypothesis might be applied to other systems including the induction of the lens, limb regeneration, and the induction of the head of hydra (124).
I have proposed this hypothesis not only because it permits consideration of a complex and varied array of experimental observations as reflections of a simple basic biochemical mechanism, but because recent technical advances in instrumentation and methods allow it to be directly tested. The fluorescent antibody method for the cytochemical measurement of cyclic nucleotides provides a means for investigating changes in the concentrations of cyclic nucleotides in developing cells and could also be used to detect neurotransmitters in developing cells. Similarly, the scanning electron microscope in the emitted x-ray mode provides a method for measuring changes in the content and distribution of cations within developing cells.
The hypothesis presented here suggests pleasing asceticism on the part of eukaryotes. It suggests that simple derivatives of metabolites, including neurotransmitters and cyclic nucleotides, are linked together as regulatory molecules throughout the eukaryotes. The neurotransmitters are suggested to have a more general role in information transmission in eukaryotes than is generally accepted. They are hypothesized to have progressed during evolution from being intracellular messengers to a role as intercellular messengers for the relatively slow communication of developmental informaton; and, finally, this process has culminated with their participation in the rapid intercellular communication mediated by nerves. The thought that the complex pictures of physiological regulation and of the construction of a complex multicellular organism like man might be painted with so few colors is quite satisfying.