Showing papers by "Brown University published in 1971"
TL;DR: Recovery from habituation was greater for a given acoustic difference when the two stimuli were from different adult phonemic categories than when they were from the same category.
Abstract: Discriminiationi of synthetic speech sounds was studied in 1- and 4-month-old infants. The speech sounds varied along an acoustic dimension previously shown to cue phonemic distinctions among the voiced and voiceless stop consonants in adults. Discriminability was measured by an increase in conditioned response rate to a second speech sound after habituation to the first speech sound. Recovery from habituation was greater for a given acoustic difference when the two stimuli were from different adult phonemic categories than when they were from the same category. The discontinuity in discrimination at the region of the adult phonemic boundary was taken as evidence for categorical perception.
1,791 citations
TL;DR: In this article, the theoretical foundations of constitutive relations at finite strain for a class of solids exhibiting inelasticity as a consequence of specific structural rearrangements, on the microscale, of constituent elements of material.
Abstract: This paper is a study of the theoretical foundations of constitutive relations at finite strain for a class of solids exhibiting inelasticity as a consequence of specific structural rearrangements, on the microscale, of constituent elements of material. Metals deforming plastically through dislocation motion are of this class and form the primary application of the theory. The development is in terms of a general internal-variable thermodynamic formalism for description of the microstructural rearrangements, and it is shown how metal plasticity may be so characterized. The principal result is in the normality structure which is shown to arise in macroscopic constitutive laws when each of the local microstructural rearrangements proceeds at a rate governed by its associated thermodynamic force. This provides a theoretical framework for time-dependent inelastic behavior in terms of a “flow potential”, and reduces to statements on normality of strain increments to yield surfaces in the time-independent case. Conventional characterizations of the stress-state dependence of metallic slip are noted to be in accord with this concept of associated forces governing rates, so that the resulting normality structure may be considered directly applicable to metal plasticity.
1,573 citations
TL;DR: In this article, the critical indices for the two-dimensional Ising model were derived from an assumed form of an operator algebra which describes how the product of two fluctuating variables may be reduced to a linear combination of the basic variables.
Abstract: A previous publication showed how the critical indices for the two-dimensional Ising model could be derived from an assumed form of an operator algebra which describes how the product of two fluctuating variables may be reduced to a linear combination of the basic fluctuating variables. In this paper, the previously used algebra is derived from the Onsager solution of the two-dimensional Ising model. The calculation makes use of a "disorder" variable which is mathematically the result of applying the Kramers-Wannier transformation to the Ising-model spin variable. The average of products of spin and disorder variables are evaluated at the critical point for the special case in which all the variables lie on a single straight line. The ordering of these variables on the line determines a "quantum number" $\ensuremath{\Gamma}$ such that the average is nonzero only for $\ensuremath{\Gamma}=0$. Composition rules for this quantum number are derived and used to develop an algebra for the multiplication of complex variables at the critical point. Arguments are given to suggest the identifications of elements of the algebra as the spin, the energy density, the Kaufman spinors, and a stress density. The result of this calculation is the operator algebra which formed the starting point of the previous paper.
421 citations
TL;DR: An algorithm andFortran-iv computer program, Cabfac, forQ-mode factor analysis is described, which will accept up to 1500 items and 50 variables on a moderate-size computer.
Abstract: An algorithm andFortran-iv computer program,cabfac, forQ-mode factor analysis is described. The program will accept up to 1500 items and 50 variables on a moderate-size computer.
394 citations
TL;DR: In this article, a new type of finite element is introduced which embodies the inverse square root singularity of the stress distribution arising near a crack in an elastic medium, and the authors used this element near the crack tip in two typical cracked configurations, with meshes having as few as 250 degrees of freedom.
239 citations
238 citations
TL;DR: The checkboard model is a computer simulation of social interaction among members of two groups as discussed by the authors, where the checkboard represents a social field on which two groups of checkers move on the board on the basis of positive, neutral or negative attitudes toward one another assigned to them.
Abstract: The checkerboard model is a computer simulation of social interaction among members of two groups. The checkerboard represents a social field on which two groups of checkers move on the board on the basis of positive, neutral or negative attitudes toward one another assigned to them. The resulting pattern of positions of the pieces represents the social structure. The theoretical basis for the checkerboard model is explained and the rules for operating the model are outlined. This is followed by illustrative runs named Crossroads, Mutual Suspicion, Segregation, Social Climber, Social Worker, Boy‐Girl, Couples and Husband‐Wives, showing intermediate and final positions on the board for each. It is concluded that the checkerboard model is capable of demonstrating the intimate connection between attitudes of group members toward their own group and toward others to a continuous social interactional process and to the resulting social structure.
225 citations
TL;DR: Analytical results of this method correlate closely with comparisons based upon the sequence of amino acids within the three families of related proteins tested: hemoglobins, light chains of myeloma proteins and cytochromes.
Abstract: 1. 1. A method is presented for the determination of relatedness among proteins based upon statistical analysis of differences in amino acid composition. 2. 2. Analytical results of this method correlate closely with comparisons based upon the sequence of amino acids within the three families of related proteins tested: hemoglobins, light chains of myeloma proteins and cytochromes. 3. 3. The method is applied to immunoglobulins for which amino acid sequence data are not available and general conclusions are drawn regarding the evolutionary relationships of these immunoglobulins.
210 citations
TL;DR: Elastic-plastic finite element analysis of near crack tip stress and strain field structure was performed in this article, where the authors used a finite element finite element (FME) model.
Abstract: Elastic-plastic finite element analysis of near crack tip stress and strain field structure
TL;DR: The problems in the analysis of surface structures by means of electron diffraction, particularly at low energy, are reviewed in this paper, where the basic scattering and diffraction phenomena occurring at a solid surface is described.
TL;DR: In this paper, the authors measured the stress dependence of the indirect exciton spectrum of silicon at 77.5 K for static uniaxial compression along the [111], [001], and [110] directions with light polarized parallel and perpendicular to the stress direction, using wavelength modulation.
Abstract: We have measured the stress dependence of the indirect exciton spectrum of silicon at 77\ifmmode^\circ\else\textdegree\fi{}K, for static uniaxial compression along the [111], [001], and [110] directions with light polarized parallel and perpendicular to the stress direction, using wavelength modulation. The high stresses reached in this work ($X=1.8\ifmmode\times\else\texttimes\fi{}{10}^{10}$ dyn ${\mathrm{cm}}^{\ensuremath{-}2}$) have enabled us to accurately study the behavior of the ${\ensuremath{\Gamma}}_{{25}^{\ensuremath{'}}}$ valence-band maxima and the ${\ensuremath{\Delta}}_{1}$ conduction-band minima under stress. The stress splitting of the valence bands is produced by (i) the orbital-strain interaction, which is described by two deformation potentials ${b}_{1}$ and ${d}_{1}$, and (ii) the stress-dependent spin-orbit interaction, described by ${b}_{2}$ and ${d}_{2}$. We find that $b={b}_{1}+2{b}_{2}=\ensuremath{-}(2.10\ifmmode\pm\else\textpm\fi{}0.10)$ eV, ${b}_{2}=\ensuremath{-}(0.1\ifmmode\pm\else\textpm\fi{}0.15)$ eV, $d={d}_{1}+2{d}_{2}=\ensuremath{-}(4.85\ifmmode\pm\else\textpm\fi{}0.15)$ eV, and ${d}_{2}=\ensuremath{-}(0.05\ifmmode\pm\else\textpm\fi{}0.25)$ eV. The same measurements yield a value for the shear deformation potential of the ${\ensuremath{\Delta}}_{1}$ conduction-band minimum ${\mathcal{E}}_{2}=\ensuremath{-}(8.6\ifmmode\pm\else\textpm\fi{}0.4)$ eV. The effect of hydrostatic deformation is interpreted in terms of two deformation potentials: ${\mathcal{E}}_{1}+{a}_{1}$ (orbital-strain interaction) and ${a}_{2}$ (stress-dependent spin-orbit interaction). We obtain ${\mathcal{E}}_{1}+{a}_{1}=+(1.5\ifmmode\pm\else\textpm\fi{}0.3)$ eV and ${a}_{2}=0$. The hydrostatic coefficient of the indirect gap obtained from ${\mathcal{E}}_{1}+{a}_{1}$ agrees with hydrostatic pressure measurements. In addition the stress-induced coupling between ${\ensuremath{\Delta}}_{1}$ minima and the neighboring ${\ensuremath{\Delta}}_{{2}^{\ensuremath{'}}}$ conduction band, described by the deformation potential $|{\mathcal{E}}_{2}^{*}|=(8\ifmmode\pm\else\textpm\fi{}3)$ eV, has been observed. Interpretation of the stress dependence of the intensities on the basis of one (${\ensuremath{\Gamma}}_{15,c}$ or ${\ensuremath{\Delta}}_{5,v}$) or two (${\ensuremath{\Gamma}}_{15,c}$ and ${\ensuremath{\Delta}}_{5,v}$) intermediate states gives the first conclusive evidence of a contribution of ${\ensuremath{\Delta}}_{5,v}\ensuremath{\rightarrow}{\ensuremath{\Delta}}_{1,c}$ virtual transitions to the indirect adsorption edge of this material.
TL;DR: The hypothesis is presented that the microtubules of the sensory process play an important role in mechanoelectric transduction in cockroach campaniform sensilla.
Abstract: Campaniform sensilla on cockroach legs provide a good model system for the study of mechanoreceptive sensory transduction. This paper describes the structure of campaniform sensilla on the cockroach tibia as revealed by light- and electron-microscopy. Campaniform sensilla are proprioceptive mechanoreceptors associated with the exoskeleton. The function of each sensillum centers around a single primary sense cell, a large bipolar neuron whose 40 µ-wide cell body is available for electrophysiological investigation with intracellular microelectrodes. Its axon travels to the central nervous system; its dendrite gives rise to a modified cilium which is associated with the cuticle. The tip of the 20 µ-long dendrite contains a basal body, from which arises a 9 + 0 connecting cilium. This cilium passes through a canal in the cuticle, and expands in diameter to become the sensory process, a membrane-limited bundle of 350–1000 parallel microtubules. The tip of the sensory process is firmly attached to a thin cap of exocuticle; mechanical depression of this cap, which probably occurs during walking movements, effectively stimulates the sensillum. The hypothesis is presented that the microtubules of the sensory process play an important role in mechanoelectric transduction in cockroach campaniform sensilla.
TL;DR: In this paper, the existence and uniqueness theorems for stochastic evolution equations are developed in a Hilbert space context, based on a blending of the theoremologies for evolution equations with stochiastic integration for Hilbert space valued random processes.
TL;DR: In this article, Liapunov stability properties of solution to a certain system of Volterra integrodifferential equations are studied, and sufficient conditions for uniform stability and uniform asymptotic stability are derived in the form of a theorem.
TL;DR: In this article, the authors analyzed the distribution of silicate species in silicate melts using the techniques of conventional polymer chemistry and found that the structure of a melt is dominated by the SiO4 monomer at low silica compositions.
TL;DR: In this article, the growth and coalescence of cylindrical voids in rigid-plastic, strain-hardening material is considered, and the exact relation among the pertinent variables: transverse stress, axial strain, hardening coefficient, void strain and void growth rate is presented.
TL;DR: In this paper, a theory of the machining of fiber-reinforced materials is pre sented, restricted to plane deformations of incom pressible composites reinforced by strong parallel fibers.
Abstract: A theory of the machining of fiber-reinforced materials is pre sented. The analysis is restricted to plane deformations of incom pressible composites reinforced by strong parallel fibers. Complete deformation and stress fields, as well as estimates of the forces re quired to maintain continuous machining, are derived. The results apply to both elastic and plastic stress responses.
TL;DR: In this article, individual scales of odor intensity were obtained for 28 different chemical compounds by the method of magnitude estimation, and it was found that power functions described the relationship between partial vapor pressure of the odorants and their subjective odor intensity for all Ss, all exponents were less than one but varied greatly between Ss.
Abstract: Individual scales of odor intensity were obtained for 28 different chemical compounds by the method of magnitude estimation. Eleven Ss participated in an experiment with 196 olfactory stimuli which differed in both quality and intensity. It was found (1) that power functions described the relationship between partial vapor pressure of the odorants and their subjective odor intensity for all Ss, (2) that all exponents were less than one but varied greatly between Ss, (3) that consistent intraindividual differences in the exponents of different odorants exist, and (4) that these are attributable to perceptual differences rather than to response bias.
TL;DR: Differentiability of nonlinear Volterra integral equations of second kind with convolutional weakly singular kernels with second-order convolution kernels was studied in this paper, where the authors showed that nonlinear integral equations can be differentiable with second kind kernels.
Abstract: Differentiability of nonlinear Volterra integral equations of second kind with convolutional weakly singular kernels
TL;DR: In this paper, the viscosity of nitrogen, argon, and helium at 25°C was measured over a nominal range of pressures 1 −100 atm and at very closely spaced density intervals.
TL;DR: In this paper, the authors developed a general and meaningful theory of dissipative periodic systems on Banach spaces, where the solutions will be unique only in the forward direction of time and the state spaces are not locally compact.
Abstract: : The objective of this paper is to develop a general and meaningful theory of dissipative periodic systems. For ordinary periodic differential equations one studies the iterates of a map T of a state space into itself where the map T is topological and the space is locally compact (n-dimensional Euclidean space). However, for the applications the authors have in mind, the solutions will be unique only in the forward direction of time and the state spaces are not locally compact. Because of this generalization of the results for ordinary differential equations is by no means trivial. The basic theory of dissipative periodic processes on Banach spaces are developed in Sections 2 and 3 of the paper. How this applies to retarded functional differential equations of retarded type is discussed in the fourth section. Two sufficient conditions for dissipativeness are given in terms of Liapunov functions. They formalize the intuitive notion that many systems for large displacements dissipate energy. Application of these results is illustrated. (Author)
TL;DR: In this paper, large differences in the intensity of phonons of different polarizations propagating ballistically in LiF, KCl, and NaF were observed by means of heat-pulse experiments carried out on single crystals, in the temperature range 1.5-3.5 \ifmmode^\circ\else\textdegree\fi{}K.
Abstract: Large differences (up to a factor of 100) have been observed in the intensity of phonons of different polarizations propagating ballistically in LiF, KCl, and ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$. These observations were made by means of heat-pulse experiments carried out on single crystals, in the temperature range 1.5-3.5 \ifmmode^\circ\else\textdegree\fi{}K. The results are explained in terms of phonon focusing due to the fact that in elastically anisotropic crystals the phonon phase and group velocities are, in general, not collinear. Calculations of the focusing effect, to determine the relative intensities of phonons of each polarization in many crystal directions, have been carried out for a number of solids. The results of these calculations are in good agreement with the experimental results obtained in this study, as well as with those obtained by other investigators on Si, Ge, and NaF.
TL;DR: Cumulative prevalence rates of asthma, nonseasonal allergic rhinitis, and seasonal hay fever by age of onset of each condition are given and suggest that the positive pollen scratch test reaction precedes the onset of clinical symptoms of hay fever.
Abstract: Histories of allergy were obtained from 1,836 freshmen college students, and 1,243 of these students were also scratch tested with 15 allergens Three years later, 1,352 of these students participated in a follow-up study designed to determine new allergies which had developed since their entrance into college as freshmen Sixty-four new cases of hay fever, nonseasonal allergic rhinitis, and/or bronchial asthma were identified in the population The frequency of new hay fever that developed among 614 senior students who had no clinical manifestation of allergy as freshmen is over ten times higher in students with initially positive pollen scratch tests (182 per cent) than in students with negative pollen scratch tests (17 per cent) Students with a 2+ or greater pollen scratch test reaction subsequently developed hay fever significantly more frequently than students with no positive pollen scratch tests The data also suggest that the positive pollen scratch test reaction precedes the onset of clinical symptoms of hay fever Cumulative prevalence rates of asthma, nonseasonal allergic rhinitis, and seasonal hay fever by age of onset of each condition are given Of the students who first had onset of hay fever and were at risk to develop asthma, only 53 per cent have subsequently developed asthma