Concept Identification as a Function of three Semantic Dimensions

It is the purpose of the present study to determine the differential effects of the three primary semantic dimensions on the ability of Ss to solve a concept identification problem. It was hypothesized that the performance level, as measured by a criterion of learning ten successive responses containing no more than one error, time to completion, and the total number of errors, will be higher for Ss working on the evaluative dimension than for Ss working on the potency or activity dimensions. Two additional hypotheses were formulated in an attempt to answer the following questions: 1) Is the ability to identify concepts a function of verbal or mathematical ability?; and 2) Will those \u27Who display a high level of verbal or mathematical ability reach the criterion of learning more rapidly

Disordered Heteropolymers with Crosslinks - Phase Diagram and Conformational Transitions

We study the phase behavior of random heteropolymers (RHPs) with quenched cross-links, a novel polymer class of technological and biological relevance, and show the possible occurrence of freezing with few chain conformations sampled. The sensitivity of the frozen phase microstructure to the disorder components is elucidated at positive solubility parameter values; at low T's segregated microphases form, while at a finite T, a first order conformational transition occurs, and is attributed to statistical matching of large microphases bounded by cross-links. The end of the symmetry broken regime stabilization by cross-links occurs at a higher T by a second order conformational transition. \\icrophases form, while at a finite T, a first order conformational transition occurs, and is attributed to statistical matching of large microphases bounded by cross-links. The end of the symmetry broken regime stabilization by cross-links occurs at a higher T by a second order conformational transition.Comment: 5 pages, 2 ps. figures. submitted to Chem. Phys. Let

Bioenergetics in two pulmonate snails, Helisoma and Physa

Energy budgets constructed for the pulmonate snails, Physa gyrina and Helisoma trivolvis, indicate:Abstract1. 1. Assimilation efficiency in wild type Physa (88[middle dot]9 per cent) and Helisoma (73[middle dot]2 per cent) are exceptionally high when compared to reported values for invertebrates while assimilation efficiency in an albino strain of Helisoma, although above average for most invertebrates, is comparatively low (59[middle dot]8 per cent).2. 2. With a single exception, there are no relationships between weight or weight gain and food (energy) ingested, wastes (energy) egested, assimilation efficiency or energy devoted to reproduction.3. 3. Daily food energy ingested by wild P. gyrina (27[middle dot]5 cal/day) and H. trivolvis (27[middle dot]6 cal/day) are similar and significantly higher than daily food energy ingested by albino H. trivolvis (15[middle dot]9 cal/day).4. 4. Albino H. trivolvis devoted more energy to egg production (2[middle dot]1 cal/day) than did the wild variety (1[middle dot]1 cal/day).5. 5. Secondary productivity of both varieties of H. trivolvis were exceptionally high (17[middle dot]8 and 32[middle dot]6 per cent).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22019/1/0000435.pd

Ground state of a double-exchange system containing impurities: bounds of ferromagnetism

We study the boundary between ferromagnetic and non-ferromagnetic ground state of a double-exchange system with quenched disorder for arbitrary relation between Hund exchange coupling and electron band width. The boundary is found both from the solution of the Dynamical Mean Field Approximation equations and from the comparison of the energies of the saturated ferromagnetic and paramagnetic states. Both methods give very similar results. To explain the disappearance of ferromagnetism in part of the parameter space we derive from the double-exchange Hamiltonian with classical localized spins in the limit of large but finite Hund exchange coupling the $t-J$ model (with classical localized spins).Comment: 5 pages, 8 eps figures, latex; minor typos correcte

Analysis of terahertz generation via nanostructure enhanced plasmonic excitations

This is the published version. Copyright © 2009 American Institute of PhysicsIn this paper, we conduct a quantitative study on the physical mechanism of electrons dynamics near the nanostructured metalfilmsurfaces, as well as the efficiency of generated terahertz radiation associated with different types of nanostructures. The simulation results show that although the oscillating motion of emitted electrons outside the metal surface may affect the terahertz generation efficiency to some extent, this efficiency is predominantly determined by the electric field magnitude inside the metalfilm associated with nanostructure enhanced plasmonic excitations. Due to the field enhancement effect of the nanostructure, an appropriately designed nanostructured surface could greatly enhance the strength of generated terahertz signal via the increased nonlinear interactions between the light and the nanostructures

Spontaneous Stratification in Granular Mixtures

Granular materials size segregate when exposed to external periodic perturbations such as vibrations. Moreover, mixtures of grains of different sizes spontaneously segregate in the absence of external perturbations: when a mixture is simply poured onto a pile, the large grains are more likely to be found near the base, while the small grains are more likely to be near the top. Here, we report a spontaneous phenomenon arising when we pour a mixture between two vertical plates: the mixture spontaneously stratifies into alternating layers of small and large grains whenever the large grains are rougher than the small grains. In contrast, we find only spontaneous segregation when the large grains are more rounded than the small grains. The stratification is related to the occurrence of avalanches; during each avalanche the grains comprising the avalanche spontaneously stratify into a pair of layers through a "kink" mechanism, with the small grains forming a sublayer underneath the layer of large grains.Comment: 4 pages, 6 figures, http://polymer.bu.edu/~hmakse/Home.htm

Correlations of RMT Characteristic Polynomials and Integrability: Hermitean Matrices

Integrable theory is formulated for correlation functions of characteristic polynomials associated with invariant non-Gaussian ensembles of Hermitean random matrices. By embedding the correlation functions of interest into a more general theory of tau-functions, we (i) identify a zoo of hierarchical relations satisfied by tau-functions in an abstract infinite-dimensional space, and (ii) present a technology to translate these relations into hierarchically structured nonlinear differential equations describing the correlation functions of characteristic polynomials in the physical, spectral space. Implications of this formalism for fermionic, bosonic, and supersymmetric variations of zero-dimensional replica field theories are discussed at length. A particular emphasis is placed on the phenomenon of fermionic-bosonic factorisation of random-matrix-theory correlation functions.Comment: 62 pages, 1 table, published version (typos corrected

Stochastic Model for Surface Erosion Via Ion-Sputtering: Dynamical Evolution from Ripple Morphology to Rough Morphology

Surfaces eroded by ion-sputtering are sometimes observed to develop morphologies which are either ripple (periodic), or rough (non-periodic). We introduce a discrete stochastic model that allows us to interpret these experimental observations within a unified framework. We find that a periodic ripple morphology characterizes the initial stages of the evolution, whereas the surface displays self-affine scaling in the later time regime. Further, we argue that the stochastic continuum equation describing the surface height is a noisy version of the Kuramoto-Sivashinsky equation.Comment: 4 pages, 7 postscript figs., Revtex, to appear in Phys. Rev. Let

Elastic String in a Random Medium

We consider a one dimensional elastic string as a set of massless beads interacting through springs characterized by anisotropic elastic constants. The string, driven by an external force, moves in a medium with quenched disorder. We present evidence that the consideration of longitudinal fluctuations leads to nonlinear behavior in the equation of motion which is {\it kinematically} generated by the motion of the string. The strength of the nonlinear effects depends on the anisotropy of the medium and the distance from the depinning transition. On the other hand the consideration of restricted solid on solid conditions imposed to the growth of the string leads to a nonlinear term in the equation of motion with a {\it diverging} coefficient at the depinning transition.Comment: 9 pages, REVTEX, figures available upon request from [email protected]

Detection of concealed and buried chemicals by using multifrequency excitations

This is the published version. Copyright © 2010 American Institute of PhysicsIn this paper, we present a new type of concealed and buried chemical detection system by stimulating and enhancing spectroscopic signatures with multifrequency excitations, which includes a low frequency gradient dcelectric field, a high frequency microwave field, and higher frequency infrared (IR) radiations. Each excitation frequency plays a unique role. The microwave, which can penetrate into the underground and/or pass through the dielectric covers with low attenuation, could effectively transform its energy into the concealed and buried chemicals and increases its evaporation rate from the sample source. Subsequently, a gradient dcelectric field, generated by a Van De Graaff generator, not only serves as a vapor accelerator for efficiently expediting the transportation process of the vapor release from the concealed and buried chemicals but also acts as a vapor concentrator for increasing the chemical concentrations in the detection area, which enables the trace level chemical detection. Finally, the stimulated and enhanced vapors on the surface are detected by the IR spectroscopic fingerprints. Our theoretical and experimental results demonstrate that more than sixfold increase in detection signal can be achieved by using this proposed technology. The proposed technology can also be used for standoff detection of concealed and buried chemicals by adding the remote IR and/or thermal spectroscopic and imaging detection systems