Showing papers by "University of Maryland, College Park published in 1972"
TL;DR: This article introduces a new category of social structure for the primates•the age-graded-male troop, and calls attention to the reproductive group as an organic unit that shows stages of growth and decline which may vary under different environmental circumstances.
Abstract: Selected data on primate social systems will be discussed and reinterpreted in this article, with a view toward modifying the existing concepts about the adaptive nature of these social systems (1-3). In light of recent data, we limit the concept of the multi-male troop (2) and call attention to the reproductive group as an organic unit that shows stages of growth and decline which may vary under different environmental circumstances. To this end, we introduce a new category of social structure for the primates•the age-graded-male troop. Before proceeding with the definitions and discussions, we must put the data into a historical framework.
501 citations
390 citations
TL;DR: In this article, the authors examined the effect of photoionization of a small population of neutral atoms (hydrogen or helium) in interplanetary space, and found that even if the density of the newly ionized particles is only a very small fraction of that of the solar wind, these particles can efficiently excite electromagnetic waves by means of a new collective instability.
Abstract: This article examines the consequence of the ionization (e.g., photoionization) of a small population of neutral atoms (hydrogen or helium) in interplanetary space. It is found that, even if the density of the newly ionized particles is only a very small fraction of that of the solar wind, these particles can efficiently excite electromagnetic waves by means of a new collective instability. The instability is driven by an anisotropy in kinetic energy of the newly ionized particles. The typical linear growth rate is γ ≃ (ωin/2½) (υ0⊥/c) where ωin is the plasma frequency of the newly ionized ions, and υ0⊥ is the characteristic speed of the newly ionized ions perpendicular to the ambient magnetic field in the frame of the solar wind.
358 citations
TL;DR: In this article, the statistical mechanics of one-dimensional Ginzburg-Landau fields for real, complex, and phase-only fields were studied, and results for specific heat, the order-parameter-orderparameter, and energy-density-energy-density correlation functions were presented.
Abstract: We have been studying the statistical mechanics of one-dimensional Ginzburg-Landau fields for real, complex, and phase-only fields. Here, results for the specific heat, the order-parameter-order-parameter, and energy-density-energy-density correlation functions, will be presented. Formally, these solutions are of interest because they describe the behavior of systems which are nearly ordered but do not undergo sharp phase transitions. Physically, the real-field results may have application in some organic chain systems, while the complex field and phase-only fields are associated with superconducting strips and linear arrays of coupled weak links, respectively.
332 citations
TL;DR: It is found that the algorithm operating with the triangular array is the most sensitive to image irregularities and noise, yet it will yield a thinned image with an overall reduced number of points.
Abstract: In this report three thinning algorithms are developed: one each for use with rectangular, hexagonal, and triangular arrays. The approach to the development of each algorithm is the same. Pictorial results produced by each of the algorithms are presented and the relative performances of the algorithms are compared. It is found that the algorithm operating with the triangular array is the most sensitive to image irregularities and noise, yet it will yield a thinned image with an overall reduced number of points. It is concluded that the algorithm operating in conjunction with the hexagonal array has features which strike a balance between those of the other two arrays.
234 citations
TL;DR: In this article, a statistical expression for the surface tension of a liquid-vapor interface is derived, which contains the density profile and the direct correlation function in the vicinity of the interface.
Abstract: We derive a statistical mechanical expression for the surface tension of a liquid-vapor interface. It contains the density profile and the direct correlation function in the vicinity of the interface. When a local Ornstein-Zernike approximation is made on the direct correlation function, the surface-tension theory of Fisk and Widom is obtained.
231 citations
Book•
01 Jan 1972187 citations
TL;DR: In this paper, the 2p-3h character of negative-parity states of 15 N was studied using the two-particle transfer 13 C( 3 He, p) 15 N reaction.
185 citations
TL;DR: Alfalfa, orchard grass, native grass, and mixtures of 31 hay and 16 silage heat damaged samples on which in vivo digestibility had been determined, were assembled to relate laboratory estimates to nitrogen digestibility as discussed by the authors.
176 citations
TL;DR: Two subjects could reliably report when, and in which direction, loads were applied to their eyes in total darkness indicating that they were aware of inflow (afferent) eye position information, showing that this inflow information can be used for extraretinal oculomotor control.
172 citations
TL;DR: Weber's interpretation of his observations involving a source at the center of the Galaxy isotropically radiating in the form of gravitational waves is discussed in this article, and directions are suggested in which more satisfactory theories of the source can be sought.
Abstract: Weber's (1971) interpretation of his observations involving a source at the center of the Galaxy isotropically radiating in the form of gravitational waves is discussed. The gravitational-wave flux at the earth is presumed to be that indicated by Weber's experiments, and directions are suggested in which more satisfactory theories of the source can be sought.
TL;DR: In this article, the long-time behavior of velocity-correlation functions for self-diffusion, viscosity, and heat conductivity for a gas of hard disks or hard spheres on the basis of the kinetic theory of dense gases is calculated.
Abstract: The long-time behavior of velocity-correlation functions ${\ensuremath{\rho}}^{(d)}(t)$ characteristic for self-diffusion, viscosity, and heat conductivity is calculated for a gas of hard disks or hard spheres on the basis of the kinetic theory of dense gases. In $d$ dimensions one finds that ${\ensuremath{\rho}}^{(d)}(t)$, after an initial exponential decay for a few mean free times ${t}_{0}$, exhibits for times up to at least $\ensuremath{\sim}40{t}_{0}$ a decay $\ensuremath{\sim}{\ensuremath{\alpha}}^{(d)}(\ensuremath{\rho}){(\frac{{t}_{0}}{t})}^{\frac{d}{2}}$, where ${\ensuremath{\alpha}}^{(d)}$ is of the order of ${\ensuremath{\rho}}^{d\ensuremath{-}1}$, $\ensuremath{\rho}=n{a}^{d}$ with $n$ the number density, and $a$ the hard-disk or hard-sphere diameter. The ${\ensuremath{\alpha}}^{(d)}(\ensuremath{\rho})$ are determined by the same dynamical events that are responsible for the divergences in the virial expansion of the transport coefficients. In this paper the ${\ensuremath{\alpha}}^{(d)}(\ensuremath{\rho})$ are calculated to lowest order in $\ensuremath{\rho}$. In this order, they are identical to the low-density limit of the ${\ensuremath{\alpha}}^{(d)}(\ensuremath{\rho})$ that have been obtained by other authors on the basis of hydrodynamical considerations.
TL;DR: An algorithm is presented to find a feasible solution which tends to minimize the number of required routes and mileage and possible extensions of the approach to school location planning, bus fleets composition and timing conditions on particular bus stops.
Abstract: This paper reports on an application of computer technology to a significant and costly school administration problem: the transportation of students between home and school. The problem, as it is generally thought of, has been complicated by the consideration of attempting racial balance via busing. We present an algorithm to find a feasible solution which tends to minimize the number of required routes and mileage. After setting down the basic approach used and the results of an application, we will present possible extensions of the approach to school location planning, bus fleets composition and timing conditions on particular bus stops.
TL;DR: In this paper, the elastic scattering of composite projectiles by nuclei is considered in the semiclassical limit, and criteria based on this description are obtained for the incident energy and angular range of data necessary to eliminate discrete ambiguities in optical potentials for such projectiles.
Abstract: The elastic scattering of composite projectiles by nuclei is considered in the semiclassical limit. Criteria based on this description are obtained for the incident energy and angular range of data necessary to eliminate discrete ambiguities in optical potentials for such projectiles. We demonstrate the effectiveness of these criteria for elastic $\ensuremath{\alpha}$-scattering data.
TL;DR: The sodium‐dependence curve for GABA uptake was markedly sigmoid and calcium strongly stimulated the initial rate of uptake at low sodium concentrations but had little effect at sodium concentrations above 100 mm and was not able to support uptake in the absence of sodium.
Abstract: — The initial rate of uptake of [2,3-3H]gamma-aminobutyric acid by rat brain synaptosomes was studied under incubation conditions in which GABA metabolism was minimal. The presence of both sodium and potassium in the incubation medium was essential for sustained uptake. Uptake proceeded for a short period of time in the absence of potassium and then ceased. No uptake was observed when sodium chloride was completely replaced with sucrose or choline chloride. The sodium-dependence curve for GABA uptake was markedly sigmoid. The sigmoid character of the curve was not attributable to a lag phase in uptake at low sodium concentrations. Calcium strongly stimulated the initial rate of uptake at low sodium concentrations but had little effect at sodium concentrations above 100 mm and was not able to support uptake in the absence of sodium. The sigmoid character of thesodium-dependence curve was completely eliminated by 20 mm calcium ion. Magnesium and phosphate had little effect on the initial rate of GABA uptake.
01 Jan 1972
TL;DR: In this paper, Milankovitch's results on radiation chronology are recomputed with the following refinements: 1) the variations in the earth's orbital elements are computed from the solutions of the differential equations for secular inequalities which include the second-order effect caused by the great inequality in the motions of Jupiter and Saturn, and are accurate to the second degree of eccentricity of the earths orbit.
Abstract: Milankovitch’s results on radiation chronology are recomputed with the following refinements: 1) The variations in the earth’s orbital elements are computed from the solutions of the differential equations for secular inequalities which include the second-order effect caused by the great inequality in the motions of Jupiter and Saturn, and are accurate to the second degree of eccentricity of the earth’s orbit. 2) The incoming solar radiation is computed for every 5° of latitude from pole to pole. 3) The radiation chronology is extended to two million years before and one hundred thousand years after 1950 A.D. 4) The value of the solar constant used is based on the most recent observations.
TL;DR: In molluscs, the amino acids utilized for volume regulation are released from the cells unchanged and are not degraded into keto-acids and ammonia as they are in the crustaceans.
Abstract: 1. Regulation of cell volume utilizing intracellular free amino acids has been studied in isolated ventricles from marine bivalves of the genus Modiolus . 2. As in the intact animal, ventricles taken from Modiolus acclimated to various salinities show only a slight change in tissue hydration. This control over cell volume is accomplished by isosmotic intracellular regulation of taurine, alanine, glycine and proline concentrations. 3. When stressed with decreased external salinities the isolated spontaneously beating ventricle becomes quiescent for a period, and then resumes activity. During the period of quiescence ninhydrin-positive substances (NPS) are released. The duration of quiscence and the amount of NPS released increase with increasing dilution of the external medium. 4. The salinity-induced NPS efflux is composed of taurine, alanine, glycine and proline. 5. In molluscs, the amino acids utilized for volume regulation are released from the cells unchanged and are not degraded into keto-acids and ammonia as they are in the crustaceans.
TL;DR: Further work is described on simple sets of parallel operations that detect "texture edges" (abrupt discontinuities in the average values of local picture properties), as well as spots or streaks that are texturally different from their surrounds.
Abstract: Further work is described on simple sets of parallel operations that detect "texture edges" (abrupt discontinuities in the average values of local picture properties), as well as spots or streaks that are texturally different from their surrounds.
TL;DR: In these experiments, the possibility that common terrestrial microorganisms carried by spacecraft can survive entry into the atmosphere of Jupiter is investigated.
Abstract: WE have investigated the possibility that common terrestrial microorganisms carried by spacecraft can survive entry into the atmosphere of Jupiter. In our experiments we used Escherichia coli B, Serratia marcescens, Aerobacter aerogenes, and Bacillus subtilis, routinely cultured in basic mineral medium1 with glucose (30 g/l.) as the carbon source, or in trypticase soy broth (TSB, 30 g/l.), sterilized by autoclaving at 15 pounds inch−2for 15 min. Plating was done using TSB with 1.5% agar.
TL;DR: In this article, experimental results were obtained for the natural frequencies and the mode shapes of graphite-epoxy and boron epoxy composite materials having fiber orientations of 0°, 15°, 30° and 90° with respect to cantilever beam axes.
Abstract: Experimental results were obtained for the natural frequencies and the mode shapes of graphite-epoxy and boron-epoxy composite materials having fiber orientations of 0°, 15° , 30° and 90° with respect to cantilever beam axes. Certain elastic constants were experimentally determined and used in a programmed numerical solution in which rotary inertia, trans verse shear, and coupled bending-torsion effects were included. The experi mental results for the 15° and 30° beams gave a clear indication of the interaction between bending and twisting and good agreement was obtained with the numerical results.
TL;DR: From 2728 events of 205-GeV $ √ p √ n interactions found in 15,000 pictures taken with the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory, a total cross section of 39.1 mb was measured.
Abstract: From 2728 events of 205-GeV $\mathrm{pp}$ interactions found in 15 000 pictures taken with the 30-in. hydrogen bubble chamber at the National Accelerator Laboratory, a total cross section of 39.5\ifmmode\pm\else\textpm\fi{}1.1 mb was measured. The mean charged-particle multiplicity for inelastic $\mathrm{pp}$ collisions was measured to be 7.65\ifmmode\pm\else\textpm\fi{}0.17. The prong distribution from 2 to 22 prongs is broader than a Poisson distribution and has a width parameter $f_{2}^{}{}_{}{}^{\ensuremath{-}}=〈{n}_{\ensuremath{-}}({n}_{\ensuremath{-}}\ensuremath{-}1)〉\ensuremath{-}{〈{n}_{\ensuremath{-}}〉}^{2}=0.95\ifmmode\pm\else\textpm\fi{}0.21$.
TL;DR: In this paper, an analysis of longwavelength magnon damping in magnetic metals is presented in the context of an itinerant-electron picture of ferromagnetism.
Abstract: An analysis of long-wavelength magnon damping in magnetic metals is presented in the context of an itinerant-electron picture of ferromagnetism. The decay is into single-particle excitations, and is a result of spin-orbit forces. The predicted dependence of the damping constant on the electron mean free path is in accord with recent experiments on ferromagnetic resonance. In particular, for pure metals it increases as the temperature is lowered, and then saturates. This anomalous rise is closely related to the anomalous electrical conductivity.
TL;DR: In this paper, the authors studied the convergence rate of the finite element method on polygonal domains in weighted Sobolev spaces, and showed that the use of different spaces of trial and test functions will restrict the usual low rate of convergence to a neighborhood of each vertex of the polygon.
Abstract: This paper is concerned with the rate of convergence of the finite element method on polygonal domains in weighted Sobolev spaces. It is shown that the use of different spaces of trial and test functions will restrict the usual low rate of convergence to a neighborhood of each vertex of the polygonal domain.L 2-convergence and lower bounds on the error are also studied.
TL;DR: In this paper, the effect of the Kerr gravitational field on wave phenomena is explored by examining the inhomogeneous wave equation for a scalar massive field in a Kerr background geometry.
Abstract: The effect of the Kerr gravitational field on wave phenomena is explored by examining the inhomogeneous wave equation for a scalar massive field in a Kerr background geometry. The equation is separated in Boyer-Lindquist coordinates. The angular functions are spheroidal harmonics, and the radial equation is reduced to a one-dimensional Schr\"odinger equation with an effective potential.
TL;DR: In this article, the critical properties of the Ashkin-Teller model in the special case where two pair energies are the same are shown to be the same as those of the eight-vertex model in weak-coupling limit as a consequence of scaling hypothesis.
TL;DR: In this paper, it was shown that the hydrodynamic frequencies for the sound, shear and heat modes in a classical hard-sphere gas have a nonanalytic dependence on the wave number k of the form Ak + Bk2 + Ck 5 2 + …. The presence of k 5 2 terms is an application of the kinetic theory which predicts the asymptotic time behavior ≃ t 3 2 of current-current correlation functions.
TL;DR: Although seemingly meaningful clusters can be obtained, the results indicate that the effort involved in finding clusters and adding the clustered terms to queries is far too great to warrant their use in an operational system.