Adnan Rebei | University of Illinois at Urbana-Champaign (original) (raw)

Papers by Adnan Rebei

How is information processed in the brain? The answer to this question is still far from being re... more How is information processed in the brain? The answer to this question is still far from being resolved. Many of the elements involved in information processing are known but understanding the whole process is a complex problem. In this work, we attempt to uncover some facets of this complexity in a process unique to human behavior, namely reading comprehension. Reading comprehension, an important task in daily life, requires the engagement of bottom-up and top-down processes in a dynamical way to speed-up processing of incoming information and make decisions about current and future expectations about the meaning of the text. Studies on lexical or syntactic ambiguity resolutions have shown that in these instances a slowing down in information integration is measured, while information processing is faster when reading underspecified text. This behavior points to different levels of information integration by the comprehender that are influenced by the complexity of the text and the...

arXiv (Cornell University), Jul 2, 2004

RePEc: Research Papers in Economics, 2020

arXiv: Neurons and Cognition, 2019

Using results from neurobiology on perceptual decision making and value-based decision making, th... more Using results from neurobiology on perceptual decision making and value-based decision making, the problem of decision making between lotteries is reformulated in an abstract space where uncertain prospects are mapped to corresponding active neuronal representations. This mapping allows us to maximize non-extensive entropy in the new space with some constraints instead of a utility function. To achieve good agreements with behavioral data, the constraints must include at least constraints on the weighted average of the stimulus and on its variance. Both constraints are supported by the adaptability of neuronal responses to an external stimulus. By analogy with thermodynamic and information engines, we discuss the dynamics of choice between two lotteries as they are being processed simultaneously in the brain by rate equations that describe the transfer of attention between lotteries and within the various prospects of each lottery. This model is able to give new insights on risk ave...

Bulletin of the American Physical Society, 2007

Submitted for the MAR07 Meeting of The American Physical Society Non-Equilibrium Spin Dynamics in... more Submitted for the MAR07 Meeting of The American Physical Society Non-Equilibrium Spin Dynamics in the Subpicosecond Regime ADNAN REBEI, Seagate Technology — Femto-second laser pulses are becoming an important tool that allows us to explore non-equilibrium spin dynamics at short time (high frequency) scales [1]. It has therefore become apparent [2] that more rigorous treatments are needed to correctly address spin relaxation at these energies. I will show how functional-methods of calculations of correlation energies in electron gas [3] can be successfully adapted to the problem of relaxation in magnetic systems [4]. The study of short time response entails a careful treatment of initial conditions. Our formalism naturally takes care of this and avoids the assumption that the system has been in equilibrium in the infinite past, an assumption common in Boltzmanntype treatments. As an example, we discuss possible non-equilibrium effects due to ultrasonic attenuation on spin relaxation ...

Bulletin of the American Physical Society, 2012

Journal of Experimental Psychology: Learning, Memory, and Cognition, 2019

Every language has unique phonotactics, general rules about how phonemes combine to make syllable... more Every language has unique phonotactics, general rules about how phonemes combine to make syllables. We know that people can implicitly learn new phonotactic rules in the laboratory, and these rules then affect their speech errors. Some types of rules, however, require a consolidation period before they influence speech errors. Two experiments are reported that replicate a recent study that transferred this finding to a nonspeech domain. In this study and our replications, the production of a consonant-vowel-consonant syllable is replaced by pushing three buttons-a finger, a thumb, and another finger. These button-push studies reproduce prior findings in the speech domain about consolidation and the retention of phonotactic learning but also point to some differences, suggesting that the massive amount of experience that adults have producing syllables leads to unique effects. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Aps Meeting Abstracts, Mar 1, 2006

Femto-second laser pulses are becoming an important tool that allows us to explore non-equilibriu... more Femto-second laser pulses are becoming an important tool that allows us to explore non-equilibrium spin dynamics at short time (high frequency) scales [1]. It has therefore become apparent [2] that more rigorous treatments are needed to correctly address spin relaxation at these energies. I will show how functional-methods of calculations of correlation energies in electron gas [3] can be successfully

The interplay between magnetism and superconductivity can be studied in simple systems such as fe... more The interplay between magnetism and superconductivity can be studied in simple systems such as ferromagnetic-superconductor-ferromagnetic tri-layers. Many recent experiments [1] measured a critical temperature dependence of the superconductor as a function of the relative orientations of the surrounding ferromagnetic layers. This layered system gives rise to an in-homogenous gap equation for the superconductor due to the polarization at the ferromagnetic-superconductor

Magnetization reversal by a femtosecond circularly polarized laser pulse has been recently demons... more Magnetization reversal by a femtosecond circularly polarized laser pulse has been recently demonstrated in rare-earth doped transition metals (RE-TM). The switching mechanism has been attributed to an inverse Faraday effect and thermal effects. Based on the parameters provided in the experimental work, we show that this claim is unlikely to give rise to femtosecond reversal. Using a hybrid itinerant-localized picture

International Journal of Modern Physics B, 1999

At finite temperature, a Fermi gas can have states that simultaneously hold a particle and a hole... more At finite temperature, a Fermi gas can have states that simultaneously hold a particle and a hole with a finite probability. This gives rise to a new set of diagrams that are absent at zero temperature. The so called "anomalous" diagram is just one of the new diagrams. We have already studied the contribution of these new diagrams to the thermodynamic potential (Phys. Lett.A224, 127 (1996)). Here we continue that work and calculate their effect on the specific heat. We will also calculate the finite temperature contribution of the ring diagrams. We conclude that the ln T behavior of the specific heat due to exchange gets canceled by the new contribution of the new diagrams, and that screening is not essential to resolve this anomaly.

SSRN Electronic Journal, 2014

It is widely believed that Closed-End Fund (CEF) discounts are due to the relatively disproportio... more It is widely believed that Closed-End Fund (CEF) discounts are due to the relatively disproportionate large numbers of small investors compared to institutional investors trading in them. An asset that is mainly traded by small investors has additional risk due to the fear factor that is usually associated with incomplete information about the market conditions. According to the present sentiment theory, noisy traders, which are usually small investors, are the reason behind CEF discounts. To test this discount theory, a closer study of the CEF funds and their correlations to various market indicators is presented. A special attention is paid to the behavior of CEFs during the financial crisis. It is shown that CEFs, contrary to popular belief, are relatively safe with small β and high α in many cases. This partially explains why CEFs are still a good investment even if they are traded at a premium and our results show that the sentiment theory cannot explain the origin of the discount.

Correlated systems are treated here from a novel angle using a functional method. Electronic syst... more Correlated systems are treated here from a novel angle using a functional method. Electronic systems at zero and non-zero temperature are treated systematically. This functional method is an extension of the usual effective potential method. Here, however the effective action is made to depend explicitly on the correlation effects that are inherent in the physics involved. This will enable us to obtain a new expression for the energy. The new expansion is shown to give the expected results for the homogeneous case. However at non-zero temperature we are able to get new sets of diagrams that have a vanishing effect at zero temperature. To lowest order these diagrams if summed properly will solve an anomaly in the specific heat of an electron gas. For the non-homogeneous case we show that this method can in principle be applied to study the effect of correlation. We argue that this method is probably better than the known density functional method when it comes to nonhomogeneity.