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Search Results: 1 - 10 of 593303 matches for " J. -M. Nunzi "
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An artificial dynamic heterogeneity in a glass-former below Tg
V. Teboul,M. Saiddine,J-M. Nunzi
Physics , 2008,
Abstract: We report the first large scale molecular dynamics simulations of the effect of the photoisomerization of probe molecules on the dynamics of a glassy molecular material. We show that the photoisomerization of the probe molecules induces the creation of an artificial dynamical heterogeneity inside the matrix. We then study the modification of the dynamics and find, in agreement with recent experiments, an important increase of the diffusion leading to liquid like diffusion below the glass transition temperature. We find that the photoisomerization process controls the heterogeneity and the non-Gaussian parameter of the material, leading to extremely rapid variations of these quantities.
Spontaneous formation of optically induced surface relief gratings
H. Leblond,R. Barille,S. Ahamadi-kandjani,J. -M. Nunzi,E. Ortyl,S. Kucharski
Physics , 2009, DOI: 10.1088/0953-4075/42/20/205401
Abstract: A model based on Fick's law of diffusion as a phenomenological description of the molecular motion, and on the coupled mode theory, is developped to describe single-beam surface relief grating formation in azopolymers thin films. It allows to explain the mechanism of spontaneous patterning, and self-organization. It allows also to compute the surface relief profile and its evolution in time with good agreement with experiments.
Multistate polarization addressing using one single beam in an azo polymer film
S. Ahmadi Kandjani,R. Barille,S. Dabos-Seignon,J. -M. Nunzi,E. Ortyl,S. Kucharski
Physics , 2005, DOI: 10.1364/OL.31.001923
Abstract: Peculiar light-matter interactions can break the rule that a single beam polarization can address only two states in an optical memory device. Multistate storage of a single beam polarization is achieved using self-induced surface diffraction gratings in a photo-active polymer material. The grating orientation follows the incident light beam polarization direction. The permanent self-induced surface relief grating can be readout in real time using the same laser beam.
Estimation of the concentration of deep traps in organic photoconductors using two-photon absorption
S. V. Novikov,A. R. Tameev,A. V. Vannikov,J. -M. Nunzi
Physics , 2013, DOI: 10.1117/12.881032
Abstract: Typically, amorphous organic materials contain high density of traps. Traps hinder charge transport and, hence, affect various working parameters of organic electronic devices. In this paper we suggest a simple but reliable method for the estimation of the concentration of deep traps (traps that keep carriers for a time much longer than the typical transport time of the device). The method is based on the measurement of the dependence of the total charge, collected at the electrode, on the total initial charge, uniformly generated in the transport layer under the action of a light pulse. Advantages and limitations of the method are discussed and an experimental example of the estimation of the density of deep traps in photoconductive organic material poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) is provided.
Nonlocal communication with photoinduced structures at the surface of a polymer film
R. Barille,S. Dabos-Seignon,J. -M. Nunzi,S. Ahmadi Kandjani,E. Ortyl,S. Kucharski
Physics , 2006, DOI: 10.1364/OPEX.13.010697
Abstract: Nonlocal communication between two laser light beams is experimented in a photochromic polymer thin films. Information exchange between the beams is mediated by the self-induction of a surface relief pattern. The exchanged information is related to the pitch and orientation of the grating. Both are determined by the incident beam. The process can be applied to experiment on a new kind of logic gates.
Incoherent light induced self-organization of molecules
S. Ahmadi Kandjani,R. Barille,S. Dabos-Seignon,J. -M. Nunzi,E. Ortyl,S. Kucharski
Physics , 2005,
Abstract: Although coherent light is usually required for the self-organization of regular spatial patterns from optical beams, we show that peculiar light matter interaction can break this evidence. In the traditional method to record laser-induced periodic surface structures, a light intensity distribution is produced at the surface of a polymer film by an interference between two coherent optical beams. We report on the self-organization followed by propagation of a surface relief pattern. It is induced in a polymer film by using a low-power and small-size coherent beam assisted by a high-power and large-size incoherent and unpolarized beam. We demonstrate that we can obtain large size and well organized patterns starting from a dissipative interaction. Our experiments open new directions to improve optical processing systems.
Multivariate Juggling Probabilities
Arvind Ayyer,Jérémie Bouttier,Sylvie Corteel,Fran?ois Nunzi
Mathematics , 2014, DOI: 10.1214/EJP.v20-3495
Abstract: We consider refined versions of Markov chains related to juggling introduced by Warrington. We further generalize the construction to juggling with arbitrary heights as well as infinitely many balls, which are expressed more succinctly in terms of Markov chains on integer partitions. In all cases, we give explicit product formulas for the stationary probabilities. The normalization factor in one case can be explicitly written as a homogeneous symmetric polynomial. We also refine and generalize enriched Markov chains on set partitions. Lastly, we prove that in one case, the stationary distribution is attained in bounded time.
Bumping sequences and multispecies juggling
Arvind Ayyer,Jérémie Bouttier,Sylvie Corteel,Svante Linusson,Fran?ois Nunzi
Mathematics , 2015,
Abstract: Building on previous work by four of us (ABCN), we consider further generalizations of Warrington's juggling Markov chains. We first introduce "multispecies" juggling, which consist in having balls of different weights: when a ball is thrown it can possibly bump into a lighter ball that is then sent to a higher position, where it can in turn bump an even lighter ball, etc. We both study the case where the number of balls of each species is conserved and the case where the juggler sends back a ball of the species of its choice. In this latter case, we actually discuss three models: add-drop, annihilation and overwriting. The first two are generalisations of models presented in (ABCN) while the third one is new and its Markov chain has the ultra fast convergence property. We finally consider the case of several jugglers exchanging balls. In all models, we give explicit product formulas for the stationary probability and closed form expressions for the normalization factor if known.
Up-conversion injection in Rubrene/Perylene-diimide-heterostructure electroluminescent diodes
Ajay K. Pandey,Jean-Michel Nunzi
Physics , 2007, DOI: 10.1063/1.2752540
Abstract: We implement and demonstrate a scheme that permits to drive electroluminescence with an extremely low turn-on voltage. The device behaves like compound semiconductors, in which the electroluminescence turn-on voltage is about the same as the open circuit voltage for the photovoltaic effect. However, the electroluminescence turn-on voltage is about half of the band gap of the emitting material, that cannot be explained using current models of charge injection in organic semiconductors. We hereby propose explanation through an Auger-type two-step injection mechanism (Auger-fountain).
A review of penile metastasis
Luigi Mearini,Renato Colella,Alessandro Zucchi,Elisabetta Nunzi
Oncology Reviews , 2012, DOI: 10.4081/oncol.2012.e10
Abstract: Penile cancer as primary disease is relatively rare in developed countries. The penis is a rare site of metastases in spite of its rich vascularization. Approximately 500 cases have been reported in the literature; almost 70% of primary lesions are of pelvic origin (from genitourinary or recto-sigmoid primary tumors). We describe a case of penile metastasis from lung cancer. The rarity of the event prompted us to also explore related reviews and discuss the incidence, physiopathology, diagnosis and therapy of penile secondary cancer.
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