Papers by Acacio de Barros
At San Francisco State, about half of the students enrolled in Liberal Studies (LS) plan to be el... more At San Francisco State, about half of the students enrolled in Liberal Studies (LS) plan to be elementary school teachers. The LS faculty consists of an anthropologist, a physicist, a geographer, a performance scholar, and a writing composition specialist. Between 2007-2009 the five faculty members developed a curriculum that integrated our areas of expertise and attempted to make students aware of different disciplinary approaches.
Recent works on the relationship between the electroencephalogram (EEG) data and psychological st... more Recent works on the relationship between the electroencephalogram (EEG) data and psychological stimuli show that EEG recordings can be used to recognize an auditory stimulus presented to a subject. The recognition rate is, however, strongly affected by technical and physiological artifacts. In this work, subjects were presented seven auditory stimuli in the form of English words (first, second, third, left, right, yes, and no), and the time--locked surface electric potentials was recorded with a 64 channel Neuroscan EEG system and related to these stimuli. We used the surface Laplacian operator to eliminate artifacts due to sources located at regions far from the electrode and to improve the recognition rates of auditory stimuli from the surface electric potentials. To compute the Laplacian, we used a spline interpolation from spherical harmonics. The EEG Laplacian during stimulation were average over trials for the same auditory stimulus, and with those averages we constructed prototypes and test samples. In addition to the Laplacian, we applied Butterworth band--pass digital filters to the averaged prototypes and test samples, and compared the filtered test samples against the prototypes using a least squares metric in the time domain. We also analyzed the effects of the spline interpolation order and band--pass filter parameters in the recognition rates. Our results suggest a spatial isomorphism between both subjects in respect to the auditory word processing.
In this paper we discuss possible quantum effects in the brain. We start with a historical review... more In this paper we discuss possible quantum effects in the brain. We start with a historical review of what some prominent physicists have said about it. We then discuss some proposals that quantum superpositions may be used by the brain. Although decoherence effects in the brain are believed to be too strong to allow quantum computations, we describe how quantum processes support the capability of some eyes to detect small number of photons. Finally, we outline how modern physics techniques may be used to perform experiments that, if successful, would show conditioning to single photons.
The spherical and the New Orleans Laplacians were compared in the classification of a two-class e... more The spherical and the New Orleans Laplacians were compared in the classification of a two-class experiment involving a stimulus driven condition and two variants of imagining the stimulus. The spherical filter produced the best results for all conditions and was the more accurate one in a test with simulations.
In this paper we discuss the use of quantum mechanics to model psychological experiments, startin... more In this paper we discuss the use of quantum mechanics to model psychological experiments, starting by sharply contrasting the need of these models to use quantum mechanical nonlocality instead of contextuality. We argue that contextuality, in the form of quantum interference, is the only relevant quantum feature used. Nonlocality does not play a role in those models. Since contextuality is also present in classical models, we propose that classical systems be used to reproduce the quantum models used. We also discuss how classical interference in the brain may lead to contextual processes, and what neural mechanisms may account for it.
The idea that synchronized oscillations are important in cognitive tasks is receiving significant... more The idea that synchronized oscillations are important in cognitive tasks is receiving significant attention. In this view, single neurons are no longer elementary computational units. Rather, coherent oscillating groups of neurons are seen as nodes of networks performing cognitive tasks. From this assumption, we develop a model of stimulus-pattern learning and recognition. The three most salient features of our model are: a new definition of synchronization, demonstrated robustness in the presence of noise, and pattern learning.
The activity of collections of synchronizing neurons can be represented by weakly coupled nonline... more The activity of collections of synchronizing neurons can be represented by weakly coupled nonlinear phase oscillators satisfying Kuramoto's equations. In this article, we build such neural-oscillator models, partly based on neurophysiological evidence, to represent approximately the learning behavior predicted and confirmed in three experiments by well-known stochastic learning models of behavioral stimulus-response theory. We use three Kuramoto oscillators to model a continuum of responses, and we provide detailed numerical simulations and analysis of the three-oscillator Kuramoto problem, including an analysis of the stability points for different coupling conditions. We show that the oscillator simulation data are well-matched to the behavioral data of the three experiments.
In this paper we discuss the existence of joint probability distributions for quantumlike respons... more In this paper we discuss the existence of joint probability distributions for quantumlike response computations in the brain. We do so by focusing on a contextual neural-oscillator model shown to reproduce the main features of behavioral stimulus-response theory. We then exhibit a simple example of contextual random variables not having a joint probability distribution, and describe how such variables can be obtained from neural oscillators, but not from a quantum observable algebra.
In this paper we propose the use of neural interference as the origin of quantumlike effects in t... more In this paper we propose the use of neural interference as the origin of quantumlike effects in the brain. We do so by using a neural oscillator model consistent with neurophysiological data. The model used was shown to reproduce well the predictions of stimulus-response theory. The quantum-like effects are produced by the spreading activation of incompatible oscillators, leading to an interference-like effect mediated by inhibitory and excitatory synapses.
In this paper we show that the GHZ theorem can be reformulated as a probablistic theorem allowing... more In this paper we show that the GHZ theorem can be reformulated as a probablistic theorem allowing for inefficiencies in the detectors. We show quantitatively that taking into account these inefficiencies, the published results of the Innsbruck experiment support the nonexistence of a joint probability distribution for the six correlated spin variables, and hence the nonexistence of hidden variables that explain the experimental results.
Foundations of Physics, Jan 1, 1994
We first show that a theorem by Cartan that generalizes the Frobenius integrability theorem allow... more We first show that a theorem by Cartan that generalizes the Frobenius integrability theorem allows us (given certain conditions) to obtain noncurvature solutions for the differential Bianchi conditions and for higher-degree similar relations. We then prove that there is no algorithmic procedure to determine, for a reasonable restricted algebra of functions on spacetime, whether a given connection form satisfies the preceding conditions. A parallel result gives a version of Gödel's first incompleteness theorem within an (axiomatized) theory of gauge fields.
In a recent paper, Nagata (Int. J. Theor. Phys. 48(12):3532, 2009) claims to derive inconsistenci... more In a recent paper, Nagata (Int. J. Theor. Phys. 48(12):3532, 2009) claims to derive inconsistencies from quantum mechanics. In this paper, we show that the inconsistencies do not come from quantum mechanics, but from extra assumptions about the reality of observables.
Recognition of words from the EEG Laplacian
International Journal of Theoretical Physics, Jan 1, 1990
We summarize ideas from Zermelo-Fraenkel set theory up to an axiomatic treatment for general rela... more We summarize ideas from Zermelo-Fraenkel set theory up to an axiomatic treatment for general relativity based on a Suppes predicate. We then examine the meaning of set-theoretic genericity for manifolds that underlie the Einstein equations. A physical interpretation is finally offered for those set-theoretically generic manifolds in gravitational theory.
Foundations of Physics Letters, Jan 1, 1994
We assume: (i) Photons are emitted by harmonically oscillating sources. (ii) They have definite t... more We assume: (i) Photons are emitted by harmonically oscillating sources. (ii) They have definite trajectories. (iii) They have a probability of being scattered at a slit. (iv) Detectors, like sources, are periodic. (v) Photons have positive and negative states which locally interfere, i.e., annihilate each other, when being absorbed. In this framework we are able to derive standard diffraction and interference results. We thereby eliminate in this approach wave-particle duality for photons, and give nonparadoxical answers to standard questions about interference. For example, in the two-slit experiment each photon goes through only one slit.
International Journal of Theoretical Physics, Jan 1, 1994
In this paper we sketch a probabilistic particle approach requiring no separate concept of wave t... more In this paper we sketch a probabilistic particle approach requiring no separate concept of wave to obtain interference. We describe in some detail how things work from a physical standpoint and show with a number of figures how the standard wave concepts are developed from purely particle random walks. For the wave concepts we have in each case a matching probability concept. The preliminary theory developed here is qualitative and stresses the physical character of the assumptions. In particular, we show that the periodic behavior of light is derived from the source and not from individual photons.
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Neste trabalho apresentamos exemplos de fenômenos metamatemticos em física. São estes dois exempl... more Neste trabalho apresentamos exemplos de fenômenos metamatemticos em física. São estes dois exemplos de incompletude em teorias físicas e um exemplo de indecidibilidade. A incompletude, num caso, está relacionadaà da aritmética e no outro a uma sentença indecidível numa teoria axiomatizada para os conjuntos, supostas as teorias todas consistentes. Em detalhe: primeiro demonstramos uma proposição que nos impõe restriçõesà forma conexão para que tenhamos soluções não triviais da identidade diferencial de Bianchi. Feito isto, exibimos uma forma conexão a respeito da qualé impossível demonstrarmos, em teorias adequadas, que ela satisfazàs restrições mencionadas. Posteriormente, arguimos sobre a relação entre "genericidade" e "aleatoriedade" em espaços-tempo da Relatividade Geral; mostramos que a identificação de tais conjuntosé também indecidível em uma teoria dos conjuntos adequada.
Wave-Function of an Asymptotically De Sitter Universe
… Journal of Modern …, Jan 1, 2007
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Papers by Acacio de Barros