8,288 research outputs found
Dissipation and spontaneous symmetry breaking in brain dynamics
We compare the predictions of the dissipative quantum model of brain with
neurophysiological data collected from electroencephalograms resulting from
high-density arrays fixed on the surfaces of primary sensory and limbic areas
of trained rabbits and cats. Functional brain imaging in relation to behavior
reveals the formation of coherent domains of synchronized neuronal oscillatory
activity and phase transitions predicted by the dissipative model.Comment: Restyled, slight changes in title and abstract, updated bibliography,
J. Phys. A: Math. Theor. Vol. 41 (2008) in prin
Stability and Diversity in Collective Adaptation
We derive a class of macroscopic differential equations that describe
collective adaptation, starting from a discrete-time stochastic microscopic
model. The behavior of each agent is a dynamic balance between adaptation that
locally achieves the best action and memory loss that leads to randomized
behavior. We show that, although individual agents interact with their
environment and other agents in a purely self-interested way, macroscopic
behavior can be interpreted as game dynamics. Application to several familiar,
explicit game interactions shows that the adaptation dynamics exhibits a
diversity of collective behaviors. The simplicity of the assumptions underlying
the macroscopic equations suggests that these behaviors should be expected
broadly in collective adaptation. We also analyze the adaptation dynamics from
an information-theoretic viewpoint and discuss self-organization induced by
information flux between agents, giving a novel view of collective adaptation.Comment: 22 pages, 23 figures; updated references, corrected typos, changed
conten
Single crystal diamond nanobeam waveguide optomechanics
Optomechanical devices sensitively transduce and actuate motion of
nanomechanical structures using light. Single--crystal diamond promises to
improve the performance of optomechanical devices, while also providing
opportunities to interface nanomechanics with diamond color center spins and
related quantum technologies. Here we demonstrate dissipative
waveguide--optomechanical coupling exceeding 35 GHz/nm to diamond nanobeams
supporting both optical waveguide modes and mechanical resonances, and use this
optomechanical coupling to measure nanobeam displacement with a sensitivity of
fm/ and optical bandwidth nm. The nanobeams are
fabricated from bulk optical grade single--crystal diamond using a scalable
undercut etching process, and support mechanical resonances with quality factor
at room temperature, and in cryogenic
conditions (5K). Mechanical self--oscillations, resulting from interplay
between photothermal and optomechanical effects, are observed with amplitude
exceeding 200 nm for sub-W absorbed optical power, demonstrating the
potential for optomechanical excitation and manipulation of diamond
nanomechanical structures.Comment: Minor changes. Corrected error in units of applied stress in Fig. 1
Contextual emergence of intentionality
By means of an intriguing physical example, magnetic surface swimmers, that
can be described in terms of Dennett's intentional stance, I reconstruct a
hierarchy of necessary and sufficient conditions for the applicability of the
intentional strategy. It turns out that the different levels of the intentional
hierarchy are contextually emergent from their respective subjacent levels by
imposing stability constraints upon them. At the lowest level of the hierarchy,
phenomenal physical laws emerge for the coarse-grained description of open,
nonlinear, and dissipative nonequilibrium systems in critical states. One level
higher, dynamic patterns, such as, e.g., magnetic surface swimmers, are
contextually emergent as they are invariant under certain symmetry operations.
Again one level up, these patterns behave apparently rational by selecting
optimal pathways for the dissipation of energy that is delivered by external
gradients. This is in accordance with the restated Second Law of thermodynamics
as a stability criterion. At the highest level, true believers are intentional
systems that are stable under exchanging their observation conditions.Comment: 27 pages; 4 figures (Fig 1. Copyright by American Physical Society);
submitted to Journal of Consciousness Studie
State transfer in dissipative and dephasing environments
By diagonalization of a generalized superoperator for solving the master
equation, we investigated effects of dissipative and dephasing environments on
quantum state transfer, as well as entanglement distribution and creation in
spin networks. Our results revealed that under the condition of the same
decoherence rate , the detrimental effects of the dissipative
environment are more severe than that of the dephasing environment. Beside
this, the critical time at which the transfer fidelity and the
concurrence attain their maxima arrives at the asymptotic value
quickly as the spin chain length increases. The transfer
fidelity of an excitation at time is independent of when the system
subjects to dissipative environment, while it decreases as increases when
the system subjects to dephasing environment. The average fidelity displays
three different patterns corresponding to , and . For
each pattern, the average fidelity at time is independent of when the
system subjects to dissipative environment, and decreases as increases when
the system subjects to dephasing environment. The maximum concurrence also
decreases as increases, and when , it arrives at an
asymptotic value determined by the decoherence rate and the structure
of the spin network.Comment: 12 pages, 6 figure
Emerging Consciousness as a Result of Complex-Dynamical Interaction Process
A quite general interaction process within a multi-component system is analysed by the extended effective potential method, liberated from usual limitations of perturbation theory or integrable model. The obtained causally complete solution of the many-body problem reveals the phenomenon of dynamic multivaluedness, or redundance, of emerging, incompatible system realisations and dynamic entanglement of system components within each realisation. The ensuing concept of dynamic complexity (and related intrinsic chaoticity) is absolutely universal and can be applied to the problem of consciousness that emerges now as a high enough, properly specified level of unreduced complexity of a suitable interaction process. This complexity level can be identified with the appearance of bound, permanently localised states in the multivalued brain dynamics from strongly chaotic states of unconscious intelligence, by analogy with classical behaviour emergence from quantum states at much lower levels of world dynamics. We show that the main properties of this dynamically emerging consciousness (and intelligence, at the preceding complexity level) correspond to empirically derived properties of natural versions and obtain causally substantiated conclusions about their artificial realisation, including the fundamentally justified paradigm of genuine machine consciousness. This rigorously defined machine consciousness is different from both natural consciousness and any mechanistic, dynamically single-valued imitation of the latter. We use then the same, truly universal concept of complexity to derive equally rigorous conclusions about mental and social implications of the machine consciousness paradigm, demonstrating its indispensable role in the next stage of civilisation development
Sampled data systems passivity and discrete port-Hamiltonian systems
In this paper, we present a novel way to approach the interconnection of a continuous and a discrete time physical system first presented in [1][2] [3]. This is done in a way which preserves passivity of the coupled system independently of the sampling time T. This strategy can be used both in the field of telemanipulation, for the implementation of a passive master/slave system on a digital transmission line with varying time delays and possible loss of packets (e.g., the Internet), and in the field of haptics, where the virtual environment should `feelÂż like a physical equivalent system
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