405 research outputs found
On the inverse optimal control problem in manual control systems
Inverse optimal control in manual control system
Modern control system theory and human control functions
Optimal control system theory applied to manual control systems - adaptive control - mathematical model
Human performance prediction in man-machine systems. Volume 1 - A technical review
Tests and test techniques for human performance prediction in man-machine systems task
Human performance prediction in man-machine systems. Part 2 - The test catalog
Human performance prediction in man machine systems - test catalog table
Cellular Structures for Computation in the Quantum Regime
We present a new cellular data processing scheme, a hybrid of existing
cellular automata (CA) and gate array architectures, which is optimized for
realization at the quantum scale. For conventional computing, the CA-like
external clocking avoids the time-scale problems associated with ground-state
relaxation schemes. For quantum computing, the architecture constitutes a novel
paradigm whereby the algorithm is embedded in spatial, as opposed to temporal,
structure. The architecture can be exploited to produce highly efficient
algorithms: for example, a list of length N can be searched in time of order
cube root N.Comment: 11 pages (LaTeX), 3 figure
Reorganization of columnar architecture in the growing visual cortex
Many cortical areas increase in size considerably during postnatal
development, progressively displacing neuronal cell bodies from each other. At
present, little is known about how cortical growth affects the development of
neuronal circuits. Here, in acute and chronic experiments, we study the layout
of ocular dominance (OD) columns in cat primary visual cortex (V1) during a
period of substantial postnatal growth. We find that despite a considerable
size increase of V1, the spacing between columns is largely preserved. In
contrast, their spatial arrangement changes systematically over this period.
While in young animals columns are more band-like, layouts become more
isotropic in mature animals. We propose a novel mechanism of growth-induced
reorganization that is based on the `zigzag instability', a dynamical
instability observed in several inanimate pattern forming systems. We argue
that this mechanism is inherent to a wide class of models for the
activity-dependent formation of OD columns. Analyzing one member of this class,
the Elastic Network model, we show that this mechanism can account for the
preservation of column spacing and the specific mode of reorganization of OD
columns that we observe. We conclude that neurons systematically shift their
selectivities during normal development and that this reorganization is induced
by the cortical expansion during growth. Our work suggests that cortical
circuits remain plastic for an extended period in development in order to
facilitate the modification of neuronal circuits to adjust for cortical growth.Comment: 8+13 pages, 4+8 figures, paper + supplementary materia
Tension Dynamics and Linear Viscoelastic Behavior of a Single Semiflexible Polymer Chain
We study the dynamical response of a single semiflexible polymer chain based
on the theory developed by Hallatschek et al. for the wormlike-chain model. The
linear viscoelastic response under oscillatory forces acting at the two chain
ends is derived analytically as a function of the oscillation frequency . We
shall show that the real part of the complex compliance in the low frequency
limit is consistent with the static result of Marko and Siggia whereas the
imaginary part exhibits the power-law dependence +1/2. On the other hand, these
compliances decrease as the power law -7/8 for the high frequency limit. These
are different from those of the Rouse dynamics. A scaling argument is developed
to understand these novel results.Comment: 23 pages, 6 figure
Understanding visual map formation through vortex dynamics of spin Hamiltonian models
The pattern formation in orientation and ocular dominance columns is one of
the most investigated problems in the brain. From a known cortical structure,
we build spin-like Hamiltonian models with long-range interactions of the
Mexican hat type. These Hamiltonian models allow a coherent interpretation of
the diverse phenomena in the visual map formation with the help of relaxation
dynamics of spin systems. In particular, we explain various phenomena of
self-organization in orientation and ocular dominance map formation including
the pinwheel annihilation and its dependency on the columnar wave vector and
boundary conditions.Comment: 4 pages, 15 figure
Conditional Quantum Dynamics and Logic Gates
Quantum logic gates provide fundamental examples of conditional quantum
dynamics. They could form the building blocks of general quantum information
processing systems which have recently been shown to have many interesting
non--classical properties. We describe a simple quantum logic gate, the quantum
controlled--NOT, and analyse some of its applications. We discuss two possible
physical realisations of the gate; one based on Ramsey atomic interferometry
and the other on the selective driving of optical resonances of two subsystems
undergoing a dipole--dipole interaction.Comment: 5 pages, RevTeX, two figures in a uuencoded, compressed fil
Coordinated optimization of visual cortical maps (I) Symmetry-based analysis
In the primary visual cortex of primates and carnivores, functional
architecture can be characterized by maps of various stimulus features such as
orientation preference (OP), ocular dominance (OD), and spatial frequency. It
is a long-standing question in theoretical neuroscience whether the observed
maps should be interpreted as optima of a specific energy functional that
summarizes the design principles of cortical functional architecture. A
rigorous evaluation of this optimization hypothesis is particularly demanded by
recent evidence that the functional architecture of OP columns precisely
follows species invariant quantitative laws. Because it would be desirable to
infer the form of such an optimization principle from the biological data, the
optimization approach to explain cortical functional architecture raises the
following questions: i) What are the genuine ground states of candidate energy
functionals and how can they be calculated with precision and rigor? ii) How do
differences in candidate optimization principles impact on the predicted map
structure and conversely what can be learned about an hypothetical underlying
optimization principle from observations on map structure? iii) Is there a way
to analyze the coordinated organization of cortical maps predicted by
optimization principles in general? To answer these questions we developed a
general dynamical systems approach to the combined optimization of visual
cortical maps of OP and another scalar feature such as OD or spatial frequency
preference.Comment: 90 pages, 16 figure
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