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Dori M.,University of Patras | Seintis K.,University of Patras | Stathatos E.,Technological and Educational Institute of Patras | Tsigaridas G.,National Technical University of Athens | And 6 more authors.
Chemical Physics Letters | Year: 2013

In this Letter, the electron injection in TiO2 films sensitized with six fluorene sensitizers is studied by femtosecond time resolved fluorescence spectroscopy using nanocrystalline Al2O3 films as reference. The sensitizers are dipolar organic molecules with the fluorene group utilized as a conjugated bridge. The electron injection efficiency is correlated to the structure, conjugation length and excited state potential of the sensitizers. One of the sensitizers has been studied using different amounts of cheno-deoxy cholic acid as co-adsorbent. In order to correlate the efficiency of electron injection with the device performance, quasi solid-state solar cells have been fabricated and characterized. Source

Asian I.,Izmir Institute of Technology | Marinakis V.,Technological and Educational Institute of Patras
Communications in Theoretical Physics | Year: 2011

Recently, many important nonlinear partial differential equations arising in the applied physical and mathematical sciences have been tackled by a popular approach, the so-called Exp-function method. In this paper, we present some shortcomings of this method by analyzing the results of recently published papers. We also discuss the possible improvement of the effectiveness of the method. © 2011 Chinese Physical Society and IOP Publishing Ltd. Source

Kouni S.N.,University of Ioannina | Giannopoulos S.,University of Ioannina | Ziavra N.,Technological and Educational Institute of Ioannina | Koutsojannis C.,Technological and Educational Institute of Patras
American Journal of Otolaryngology - Head and Neck Medicine and Surgery | Year: 2013

Purpose and background: Acoustic signals are transmitted through the external and middle ear mechanically to the cochlea where they are transduced into electrical impulse for further transmission via the auditory nerve. The auditory nerve encodes the acoustic sounds that are conveyed to the auditory brainstem. Multiple brainstem nuclei, the cochlea, the midbrain, the thalamus, and the cortex constitute the central auditory system. In clinical practice, auditory brainstem responses (ABRs) to simple stimuli such as click or tones are widely used. Recently, complex stimuli or complex auditory brain responses (cABRs), such as monosyllabic speech stimuli and music, are being used as a tool to study the brainstem processing of speech sounds. We have used the classic 'click' as well as, for the first time, the artificial successive complex stimuli 'ba', which constitutes the Greek word 'baba' corresponding to the English 'daddy'. Patients and methods: Twenty young adults institutionally diagnosed as dyslexic (10 subjects) or light dyslexic (10 subjects) comprised the diseased group. Twenty sex-, age-, education-, hearing sensitivity-, and IQ-matched normal subjects comprised the control group. Measurements included the absolute latencies of waves I through V, the interpeak latencies elicited by the classical acoustic click, the negative peak latencies of A and C waves, as well as the interpeak latencies of A-C elicited by the verbal stimulus 'baba' created on a digital speech synthesizer. Results: The absolute peak latencies of waves I, III, and V in response to monoaural rarefaction clicks as well as the interpeak latencies I-III, III-V, and I-V in the dyslexic subjects, although increased in comparison with normal subjects, did not reach the level of a significant difference (p < 0.05). However, the absolute peak latencies of the negative wave C and the interpeak latencies of A-C elicited by verbal stimuli were found to be increased in the dyslexic group in comparison with the control group (p = 0.0004 and p = 0.045, respectively). In the subgroup consisting of 10 patients suffering from 'other learning disabilities' and who were characterized as with 'light' dyslexia according to dyslexia tests, no significant delays were found in peak latencies A and C and interpeak latencies A-C in comparison with the control group. Conclusions: Acoustic representation of a speech sound and, in particular, the disyllabic word 'baba' was found to be abnormal, as low as the auditory brainstem. Because ABRs mature in early life, this can help to identify subjects with acoustically based learning problems and apply early intervention, rehabilitation, and treatment. Further studies and more experience with more patients and pathological conditions such as plasticity of the auditory system, cochlear implants, hearing aids, presbycusis, or acoustic neuropathy are necessary until this type of testing is ready for clinical application. © 2013 Elsevier Inc. All rights reserved. Source

Sellountos E.J.,University of Lisbon | Tsinopoulos S.V.,Technological and Educational Institute of Patras | Polyzos D.,University of Patras | Polyzos D.,Institute of Chemical Engineering And High Temperature Chemical Processes
CMES - Computer Modeling in Engineering and Sciences | Year: 2012

A Local Boundary Integral Equation (LBIE) method for solving two dimensional problems in gradient elastic materials is presented. The analysis is performed in the context of simple gradient elasticity, the simplest possible case of Mindlin's Form II gradient elastic theory. For simplicity, only smooth boundaries are considered. The gradient elastic fundamental solution and the corresponding boundary integral equation for displacements are used for the derivation of the LBIE representation of the problem. Nodal points are spread over the analyzed domain and the moving least squares (MLS) scheme for the approximation of the interior and boundary variables is employed. Since in gradient elasticity the equilibrium equation is a partial differential equation of forth order, the MLS is ideal for solving these problems since it holds the C (1) continuity property. The companion solution of displacements is explicitly derived and introduced in the LBIEs for zeroing the tractions and double tractions on the local circular boundaries. Two representative numerical examples are presented to illustrate the method, demonstrate its accuracy and assess the gradient effect in the response. Copyright © 2012 Tech Science Press. Source

Marinakis V.,Technological and Educational Institute of Patras
Advances in Mathematical Physics | Year: 2010

We show that a nonlinear equation that represents third-order approximation of long wavelength, small amplitude waves of inviscid and incompressible fluids is integrable for a particular choice of its parameters, since in this case it is equivalent with an integrable equation which has recently appeared in the literature. We also discuss the integrability of both second- and third-order approximations of additional cases. Copyright © 2010 V. Marinakis. Source

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