4,824 research outputs found
Cognition as Embodied Morphological Computation
Cognitive science is considered to be the study of mind (consciousness and thought) and intelligence in humans. Under such definition variety of unsolved/unsolvable problems appear. This article argues for a broad understanding of cognition based on empirical results from i.a. natural sciences, self-organization, artificial intelligence and artificial life, network science and neuroscience, that apart from the high level mental activities in humans, includes sub-symbolic and sub-conscious processes, such as emotions, recognizes cognition in other living beings as well as extended and distributed/social cognition. The new idea of cognition as complex multiscale phenomenon evolved in living organisms based on bodily structures that process information, linking cognitivists and EEEE (embodied, embedded, enactive, extended) cognition approaches with the idea of morphological computation (info-computational self-organisation) in cognizing agents, emerging in evolution through interactions of a (living/cognizing) agent with the environment
He Scattering from Random Adsorbates, Disordered Compact Islands and Fractal Submonolayers: Intensity Manifestations of Surface Disorder
A theoretical study is made on He scattering from three fundamental classes
of disordered ad-layers: (a) Translationally random adsorbates, (b) disordered
compact islands and (c) fractal submonolayers. The implications of the results
to experimental studies of He scattering from disordered surfaces are
discussed, and a combined experimental-theoretical study is made for Ag
submonolayers on Pt(111). Some of the main theoretical findings are: (1)
Structural aspects of the calculated intensities from translationally random
clusters were found to be strongly correlated with those of individual
clusters. (2) Low intensity Bragg interference peaks appear even for scattering
from very small ad-islands, and contain information on the ad-island local
electron structure. (3) For fractal islands, just as for islands with a
different structure, the off-specular intensity depends on the parameters of
the He/Ag interaction, and does not follow a universal power law as previously
proposed in the literature. In the experimental-theoretical study of Ag on
Pt(111), we use first experimental He scattering data from low-coverage (single
adsorbate) systems to determine an empirical He/Ag-Pt potential of good
quality. Then, we carry out He scattering calculations for high coverage and
compare with experiments. The conclusions are that the actual experimental
phase corresponds to small compact Ag clusters of narrow size distribution,
translationally disordered on the surface.Comment: 36 double-spaced pages, 10 figures; accepted by J. Chem. Phys.,
scheduled to appear March 8. More info available at
http://www.fh.huji.ac.il/~dani
Two controversies in classical electromagnetism
This paper examines two controversies arising within classical electromagnetism which are relevant to the optical trapping and micromanipulation community. First is the Abraham-Minkowski controversy, a debate relating to the form of the electromagnetic energy momentum tensor in dielectric materials, with implications for the momentum of a photon in dielectric media. A wide range of alternatives exist, and experiments are frequently proposed to attempt to discriminate between them. We explain the resolution of this controversy and show that regardless of the electromagnetic energy momentum tensor chosen, when material disturbances are also taken into account the predicted behaviour will always be the same. The second controversy, known as the plane wave angular momentum paradox, relates to the distribution of angular momentum within an electromagnetic wave. The two competing formulations are reviewed, and an experiment is discussed which is capable of distinguishing between the two
Power-law fluctuations in phase-separated lipid membranes
URL:http://link.aps.org/doi/10.1103/PhysRevE.60.7354
DOI:10.1103/PhysRevE.60.7354The spatial structure of three binary lipid mixtures, prepared as multilamellar vesicles, was studied by small-angle neutron scattering. In the fluid-gel coexistence region, large- scale concentration fluctuations appear which scatter like surface fractals for small acyl- chain mismatch and like mass fractals for large mismatch over about one decade of length. The transition is highly discontinuous: The fractal dimension of the boundary between the gel and fluid drops from 2.7 to 1.7, the gel fraction in the fluctuations drops from about 0.5 to 0.07, and the gel domains interlamellar correlation drops from strong to weak. We interpret the fluctuations as long-lived descendants of the incipient two-phase equilibrium state and the transition as due to changes in the gel rigidity and phase diagram.We gratefully acknowledge financial support from the Deutsch Forschungsgemeinschaft and the Petroleum Research Fund, administered by the American Chemical Society
First order wetting of rough substrates and quantum unbinding
Replica and functional renormalization group methods show that, with short
range substrate forces or in strong fluctuation regimes, wetting of a
self-affine rough wall in 2D turns first-order as soon as the wall roughness
exponent exceeds the anisotropy index of bulk interface fluctuations. Different
thresholds apply with long range forces in mean field regimes. For
bond-disordered bulk, fixed point stability suggests similar results, which
ultimately rely on basic properties of quantum bound states with asymptotically
power-law repulsive potentials.Comment: 11 pages, 1 figur
The morphofunctional approach to emotion modelling in robotics
In this conceptual paper, we discuss two areas of research in robotics, robotic models of emotion and morphofunctional machines, and we explore the scope for potential cross-fertilization between them. We shift the focus in robot models of emotion from information-theoretic aspects of appraisal to the interactive significance of bodily dispositions. Typical emotional phenomena such as arousal and action readiness can be interpreted as morphofunctional processes, and their functionality may be replicated in robotic systems with morphologies that can be modulated for real-time adaptation. We investigate the control requirements for such systems, and present a possible bio-inspired architecture, based on the division of control between neural and endocrine systems in humans and animals. We suggest that emotional epi- sodes can be understood as emergent from the coordination of action control and action-readiness, respectively. This stress on morphology complements existing research on the information-theoretic aspects of emotion
Schrodinger equation for the one particle density matrix of thermal systems: An alternative formulation of Bose-Einstein condensation
We formulate a linear Schrodinger equation with the temperature-dependent
potential for the one-particle density matrix and obtain the condensation
temperature of the Bose-Einstein condensate from a bound-state condition for
the Schrodinger equation both with and without the confining trap. The results
are in very good agreement with those of the full statistical physics
treatment. This is an alternative to the Bose-Einstein condensation in the
standard ideal Bose gas treatment.Comment: 4 pages, 2 figure
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