Speech identification based on temporal fine structure cues

The contribution of temporal fine structure (TFS) cues to consonant identification was assessed in normal-hearing listeners with two speech-processing schemes designed to remove temporal envelope (E) cues. Stimuli were processed vowel-consonant-vowel speech tokens. Derived from the analytic signal, carrier signals were extracted from the output of a bank of analysis filters. The "PM" and "FM" processing schemes estimated a phase- and frequency-modulation function, respectively, of each carrier signal and applied them to a sinusoidal carrier at the analysis-filter center frequency. In the FM scheme, processed signals were further restricted to the analysis-filter bandwidth. A third scheme retaining only E cues from each band was used for comparison. Stimuli processed with the PM and FM schemes were found to be highly intelligible (50-80% correct identification) over a variety of experimental conditions designed to affect the putative reconstruction of E cues subsequent to peripheral auditory filtering. Analysis of confusions between consonants showed that the contribution of TFS cues was greater for place than manner of articulation, whereas the converse was observed for E cues. Taken together, these results indicate that TFS cues convey important phonetic information that is not solely a consequence of E reconstruction.     

Optimisation with genetic algorithm of the acoustic performance of T-shaped noise barriers with a reactive top surface

In this study, the aim is to optimise the acoustical efficiency of T-shaped noise barriers whose top is covered with a series of wells. This research work uses an optimisation method in order to find the best noise barrier profile considering several variable parameters. Numerical simulations of the acoustical propagation are achieved by use of a 2D boundary element method code. The optimisation part is carried out with a global and direct evolutionary optimisation method: a genetic algorithm. The parameters to optimise are the shape of the protection (the depths of the wells on the crowning) and the flow resistivity of absorbing materials considered. The cost function to maximize is defined through a mean value of the acoustical efficiency of the protection compared to a reference configuration, averaged on several receiver points. Final results show significant optimised values of parameters for efficient protections in order to improve classical noise barriers.     

New nanohybrid materials for biophotonics

Hybrid nanomaterials were prepared by one- and two-step procedures in the absence of water. Femtosecond laser ablation of a ZnO target in absolute ethanol afforded a colloidal ZnO solution. Dye molecules were grafted onto the ZnO nanoparticle surface by mixing the ZnO solution with an ethanol solution of tetramethylrhodamine B isothiocyanate or rhodamine B. Formation of strongly facetted nanohybrid particles with the average size of 21 nm was observed by HRTEM measurements. Ablation of ZnO in the presence of the dyes afforded nanohybrids with the average size of 12 nm. The occurrence of energy transfer from the ZnO nanoparticles towards the attached dye molecules was demonstrated by photoluminescence spectroscopy of the nanohybrids after single and multi-photon excitations. In particular, two-photon absorption of the nanohybrids ZnO core gave rise to emission of the grafted dyes. PACS 81.07.Bc; 81.07.Nb; 78.67.Bf; 78.55.Et; 81.15.Fg     

Toward a nanoimprinted nanoantenna to perform optical rectification through molecular diodes

This work presents investigations about the realization and modelization of rectenna solar cells. Rectennas are antennas coupled with a rectifier to convert the alternative current originating from the antenna into direct current that can be harvested and stored. By reducing the size of the antennas to the nanoscale, interactions with visible and near-infrared light become possible. If techniques such as nanoimprint lithography make possible the fabrication of sufficiently small plasmonic structures to act as optical antennas, the concept of rectenna still faces several challenges. One of the most critical point is to achieve rectification at optical frequencies. To address this matter, we propose to use molecular diodes (ferrocenyl-alkanethiol) that can be self-assembled on metallic surfaces such as gold or silver. In this paper, we present a basic rectenna theory as well as finite-difference time-domain (FDTD) optical simulations of plasmonic structures and experimental results of both nanoimprint fabrication of samples and characterizations by electron microscopy, Raman spectroscopy, and cyclic voltammetry techniques.     

Compensating Doppler broadening with light-shifts

The conversion of a continuous-tone image into a sampled, pulse-modulated, binary image by means of a half-tone line screen permits a variety of non-linear operations to be carried out with a coherent optical processing system. While pulse-width modulation encoding has been used mainly so far, it is shown that pulse-position modulation encoding has some advantages.     

Algebraic fundamental group and simplicial complexes

In this paper, we prove that the fundamental group of a simplicial complex is isomorphic to the algebraic fundamental group of its incidence algebra, and we derive some applications.     

Polarographic investigations of 7-methylguanosine

The mechanism of reduction of 7-methylguanosine (7-MeGuo) in buffered solution was studied by electrochemical methods. The polarographic reduction involves complex processes due to the presence of maxima (maximum of the first kind and maximum of catalytic reduction of protons). Consequently other techniques are required such as u.v. and n.m.r. spectroscopies, and chromatography for the identification of the reduction product.A mechanism of reduction is suggested in acid medium, the reduction saturates the imidazolium ring by fixation of two electrons and one proton.     

Versatile synthesis of functionalised dibenzothiophenes via Suzuki coupling and microwave-assisted ring closure

Amino-substituted biphenyls were obtained by Suzuki cross-coupling of 2,6-dibromoaniline with a phenylboronic acid (substituted with Me, NO(2), OH, OMe or Cl) preferably assisted by microwave irradiation. Conversion of the amino group into a thiol preceded a base-induced intramolecular substitution, also facilitated by microwave heating, to generate the second C-S bond of the target dibenzothiophene. The 1-, 2-, 3- or 4-substituted 6-halodibenzothiophenes obtained were subjected to a palladium-mediated coupling with 2-morpholin-4-yl-8-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-4H-chromen-4-one to give the respective 6-, 7-, 8- or 9-substituted dibenzothiophen-4-ylchromenones. These compounds were evaluated as inhibitors of DNA-dependent protein kinase (DNA-PK) and compared to the parent 8-(dibenzo[b,d]thiophen-4-yl)-2-morpholin-4-yl-4H-chromen-4-one. Notably, derivatives bearing hydroxy or methoxy substituents at C-8 or C-9 retained activity, whereas substitution at C-7 lowered activity. Substitution with chloro at C-6 was not detrimental to activity, but a chloro group at C-7 or C-8 reduced potency. The data indicate permissive elaboration of hydroxyl at C-8 or C-9, enabling the possibility of improved pharmaceutical properties, whilst retaining potency against DNA-PK.     

Laser-assisted local patterning of ZnO-based spots for mirror-less lasing

ZnO is known as one of the best materials for the implementation of the random lasing effect, associated with mirror-less laser emission in a simultaneously amplifying and highly scattering medium. Normally, the fabrication of this medium requires a rather complicated procedure of deposition and thermal treatment of ZnO-based films on some specific substrates, yielding wurtzite-orientation ZnO nanocrystals. We demonstrate a rapid synthesis of highly efficient ZnO-based random lasing spots on a piece of Zn by employing the phenomenon of laser-induced air breakdown. Being ignited near the surface of a Zn target, plasma of the air breakdown serves as a local reactor to locally transform its properties and thus form a film of well-packed 20–40 nm ZnO nanospheres. Exhibiting extremely high amplification and scattering, this medium is capable of generating the random lasing effect within the exciton-based photoluminescent band.