125 research outputs found
Transitorium
No full textThe poems of Vassiliki Rapti … are appropriate for a kind of music of modern syncopated rhythms. Their diversity is their charm since they can be read also with their own particular minimal music. This poetry is both Alexandrian in the epigraphic style and graphic in the modernist style. Their appearance is their content, humorous and playful. A pleasure to read.
Nanos Valaoritis
Author of My Afterlife Guarantee
Soliton dynamics in linearly coupled discrete nonlinear Schrodinger equations
No full textWe study soliton dynamics in a system of two linearly coupled discrete nonlinear Schrodinger equations, which describe the dynamics of a two-component Bose gas, coupled by an electromagnetic field, and confined in a strong optical lattice. When the nonlinear coupling strengths are equal, we use a unitary transformation to remove the linear coupling terms, and show that the existing soliton solutions oscillate from one species to the other. When the nonlinear coupling strengths are different, the soliton dynamics is numerically investigated and the findings are compared to the results of an effective two-mode model. The case of two linearly coupled Ablowitz-Ladik equations is also briefly discussed. (C) 2009 IMACS. Published by Elsevier B.V. All rights reserved
Modulational instabilities and domain walls in coupled discrete nonlinear Schrodinger equations
No full textThis is the pre-published version harvested from arXiv. The published version is located at http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVM-4D2WJC6-6&_user=1516330&_coverDate=09%2F13%2F2004&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1581588698&_rerunOrigin=google&_acct=C000053443&_version=1&_urlVersion=0&_userid=1516330&md5=ecc02537d76b64908e7ece530816024a&searchtype=aWe consider a system of two discrete nonlinear Schrödinger equations, coupled by nonlinear and linear terms. For various physically relevant cases, we derive a modulational instability criterion for plane-wave solutions. We also find and examine domain-wall solutions in the model with the linear coupling.95-10
Rabi switch of condensate wavefunctions in a multicomponent Bose gas
No full textUsing a time-dependent linear (Rabi) coupling between the components of a weakly interacting multicomponent Bose-Einstein condensate (BEC), we propose a protocol for transferring the wave function of one component to the other. This "Rabi switch" can be generated in a binary BEC mixture by an electromagnetic field between the two components, typically two hyperfine states. When the wave function to be transferred is, at a given time, a stationary state of the multicomponent Hamiltonian, then, after a time delay (depending on the Rabi frequency), it is possible to have the same wave function on the other condensate. The Rabi switch can be used to transfer also moving bright matter-wave solitons, as well as vortices and vortex lattices in two-dimensional (2D) condensates. The efficiency of the proposed switch is shown to be 100% when interspecies and intraspecies interaction strengths are equal. The deviations from equal interaction strengths are analyzed within a two-mode model, and the dependence of the efficiency on the interaction strengths and on the presence of external potentials is examined in both 1D and 2D settings
Stationary solutions for a modified Peyrard-Bishop DNA model with up to third-neighbor interactions
No full textWe investigate a DNA model that takes into account stacking interactions with neighbors up to three bases away. The model is a generalization of the well-known Peyrard-Bishop (PB) model and is motivated by studies that suggest that nearest-neighbor models for base-pair interaction in a DNA chain might not be enough to capture the mechanism and dynamics of DNA base-pair opening. We study stationary solutions of the modified model and investigate their stability. A comparison with the PB model reveals that under a wide range of parameter values the main characteristics of the original model --such as the hyperbolicity of the equilibrium at the origin-- are preserved, but new types of stationary solutions emerge
Author Correction: Early treatment of COVID-19 with anakinra guided by soluble urokinase plasminogen receptor plasma levels: a double-blind, randomized controlled phase 3 trial (Nature Medicine, (2021), 27, 10, (1752-1760), 10.1038/s41591-021-01499-z)
No full textIn the version of this Article initially published, there was an error in the author affiliations. Specifically, affiliation 27, corresponding to author Carlo Selmi, has been corrected from “Humanitas Research Hospital, Milan, Italy” to read: “Department of Biomedical Sciences, Humanitas University, Milan, Italy & IRCCS Humanitas Research Hospital, Milan, Italy.” The change has been made to the online version of the Article
Parametric and modulational instabilities of the discrete nonlinear Schrödinger equation
No full textThis is the pre-published version harvested from arXiv. The published version is located at http://iopscience.iop.org/0953-4075/37/7/070/We examine the parametric and modulational instabilities arising in a non-autonomous, discrete nonlinear Schrödinger equation. The principal motivation for our study stems from the dynamics of Bose–Einstein condensates trapped in a deep optical lattice. We find that under periodic variations of the heights of the interwell barriers (or equivalently of the scattering length), in addition to the modulational instability, a window of parametric instability becomes available to the system. We explore this instability through multiple-scale analysis and identify it numerically. Its principal dynamical characteristic is that, typically, it develops over much larger times than the modulational instability, a feature that is qualitatively justified by comparison of the corresponding instability growth rates
Avaton: With 13 Paintings by Dimitris Mytaras
No full textVassiliki thoughtfully translates Avaton, which is a collection of poems by author Dimitros Bafaloukos. This collection of poems captures anguished love either triumphed beyond wounds or remaining unfulfilled. Using his skills of precision and his pen, Bafaloukos is able to draw upon moments of profound love to immortalize Eros. The poems are amplified by the use of thirteen paintings from artist Dimitris Mytaras, which creates a unique poetic-visual dialogue
On the Modulational Instability of the Nonlinear Schrödinger Equation with Dissipation
No full textThis is the pre-published version harvested from arXiv. The published version is located at http://iopscience.iop.org/1402-4896/2004/T113/019The modulational instability (MI) of spatially uniform states in the nonlinear Schrödinger (NLS) equation is examined in the presence of higher-order dissipation. The study is motivated by results on the effects of three-body recombination in Bose-Einstein condensates (BECs), as well as by the important recent work of Segur et al. on the effects of linear damping in NLS settings. We show how the presence of even the weakest possible dissipation suppresses the instability on a longer time scale. However, on a shorter scale, the instability growth may take place, and a corresponding generalization of the MI criterion is developed. The analytical results are corroborated by numerical simulations. The method is valid for any power-law dissipation form, including the constant dissipation as a special case.7
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