666 research outputs found

    Multi-resonant scatterers in sonic crystals: Locally multi-resonant acoustic metamaterial

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    An acoustic metamaterial made of a two-dimensional (2D) periodic array of multi-resonant acoustic scatterers is analyzed both experimentally and theoretically. The building blocks consist of a combination of elastic beams of low-density polyethylene foam (LDPF) with cavities of known area. Elastic resonances of the beams and acoustic resonances of the cavities can be excited by sound producing several attenuation peaks in the low frequency range. Due to this behavior the periodic array with long wavelength multi-resonant structural units can be classified as a locally multi-resonant acoustic metamaterial (LMRAM) with strong dispersion of its effective properties. The results presented in this paper could be used to design effective tunable acoustic filters for the low frequency range. (C) 2012 Elsevier Ltd. All rights reserved.This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and FEDER funds, under Grants MAT2009-09438 and MTM2009-14483-C02-02. V.R.G. is grateful for the support of "Programa de Contratos Post-Doctorales con Movilidad UPV (CEI-01-11)". A.K. and O.U. are grateful for the support of EPSRC (UK) through research Grant EP/E063136/1.Romero García, V.; Krynkin, A.; García-Raffi, LM.; Umnova, O.; Sánchez Pérez, JV. (2013). Multi-resonant scatterers in sonic crystals: Locally multi-resonant acoustic metamaterial. Journal of Sound and Vibration. 332(1):184-198. doi:10.1016/j.jsv.2012.08.003S184198332

    Multi-dimensional adaptation in MAS organizations

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    © 2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Organization adaptation requires determining the consequences of applying changes not only in terms of the benefits provided but also measuring the adaptation costs as well as the impact that these changes have on all of the components of the organization. In this paper, we provide an approach for adaptation in multiagent systems based on a multidimensional transition deliberation mechanism (MTDM). This approach considers transitions in multiple dimensions and is aimed at obtaining the adaptation with the highest potential for improvement in utility based on the costs of adaptation. The approach provides an accurate measurement of the impact of the adaptation since it determines the organization that is to be transitioned to as well as the changes required to carry out this transition. We show an example of adaptation in a service provider network environment in order to demonstrate that the measurement of the adaptation consequences taken by the MTDM improves the organization performance more than the other approaches.Manuscript received January 2, 2012; revised July 26, 2012; accepted August 7, 2012. Date of publication August 31, 2012; date of current version April 16, 2013. This work was supported in part by projects TIN2008-04446 and TIN2009-13839-C03-01. J. M. Alberola received a Grant from Ministerio de Ciencia e Innovacion de Espana (AP2007-00289). This paper was recommended by Associate Editor J. Huang.Alberola Oltra, JM.; Julian Inglada, VJ.; García-Fornes, A. (2013). Multi-dimensional adaptation in MAS organizations. IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics. 43(2):622-633. https://doi.org/10.1109/TSMCB.2012.2213592S62263343

    Mechanisms of resistance to QoI fungicides in phytopathogenic fungi

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    The major threat to crops posed by fungal diseases results in the use by growers of enormous amounts of chemicals. Of these, quinol oxydation inhibitors (QoIs) are probably the most successful class of agricultural fungicides. QoIs inhibit mitochondrial respiration in fungi by binding to the Qo site of the cytochrome bc1 complex, blocking electron transfer and halting ATP synthesis. Unfortunately, the rapid development of resistance to these fungicides and consequent control failure has become increasingly problematic. The main mechanism conferring resistance to QoIs is target site modification, involving mutations in the cytochrome b gene CYTB, such as the substitution of glycine by alanine at position 143 (G143A) that occurs in several phytopathogenic fungi. The impact of other mechanisms, including alternative respiration and efflux transporters, on resistance seems to be limited. Interestingly, in some species QoI resistance is not supported by mutations in CYTB, while in others the structure of the gene is such that it is unlikely to undergo G143A mutations. Better understanding of the biological basis of QoI resistance in a single pathogen species will facilitate the development of resistance diagnostic tools as well as proper anti-resistance strategies aimed at maintaining the high efficacy of these fungicides. [Int Microbiol 2008; 11(1):1-9

    Aportaciones a la flora de AndalucĂ­a.

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    New data on the Andalusian flora. Palabras clave. Papaver, Erica, Convolvulus, Teucrium, flora, corología, Andalucía, España.Key words. Papaver, Erica, Convolvulus, Teucrium, flora, chorology, Andalusia, Spain

    A Method for Estimation of Population-Densities of Ice Nucleating Active Pseudomonas-Syringae in Buds and Leaves of Mango

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    Active ice nucleation strains of Pseudomonas syringae pv. syringae have been associated with a necrotic disease in mango trees growing in Málaga (southern Spain). In this paper a simple multiple-tube test is described to estimate the number of active ice nucleation bacteria associated with plant tissues and, also from suspensions of isolated bacterial strains.Peer reviewe

    Level repulsion and evanescent waves in sonic crystals

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    This work theoretically and experimentally reports the evanescent connections between propagating bands in periodic acoustic materials. The complex band structures obtained by solving for the k(¿) problem reveal a complete interpretation of the propagation properties of these systems. The prediction of evanescent modes, nonpredicted by classical ¿(k - ) methods, is of interest for the understanding of these propagation properties. Complex band structures provide an interpretation of the evanescent coupling and the level repulsion states showing the possibility of controlling evanescent waves in periodic materials. © 2011 American Physical Society.V.R.G. and L.M.G.R. would like to thank the facilities provided by the IEMN UMR CNRS 8520. L.M.G.R. would like to thank the UPV for Grant No. PAID-00-11. V.R.G. is grateful for the support contracts of the UPV CEI-01-11. This work was supported by MCI Secretaria de Estado de Investigacion (Spanish government) and the FEDER funds, under Grant No. MAT2009-09438.Romero García, V.; Vasseur, J.; Hladky Hennion, AC.; García Raffi, LM.; Sánchez Pérez, JV. (2011). Level repulsion and evanescent waves in sonic crystals. Physical Review B. 84:2123021-2123024. https://doi.org/10.1103/PhysRevB.84.212302S212302121230248

    Age differences in selected measures of physical fitness in young handball players

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    [EN] Objective: The aims of the present study were: 1) to calculate the change of direction (COD) deficit (using a modified version of the 505 test and 10 m sprint time), and (2) to examine the differences in linear sprint, jump and COD performances, as well as COD deficit, between under-13 (U13) and under-15 (U15) male handball players. Methods: One hundred and nineteen young male handball players (under-13 [U13; n = 82] and under-15 [U15; n = 37]). Tests included anthropometric measurements, countermovement jump (CMJ), triple leg-hop for distance, linear sprint test (5, 10 and 20 m), and a modified version of the 505 COD test. Results: Results showed moderate to very large differences (P 0.05). Conclusions: Our results suggest that during the transition from pre- to post-puberty, young handball players should focus on transferring their progressive improvements in strength, speed, and power capacities to COD performance.S

    Optical performance of a new design of trifocal intraocular lens based on the Devil's diffractive lens

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    In this work, we propose a new diffractive trifocal intraocular lens design with focus extension, conceived to provide a high visual performance at intermediate distances. This design is based on a fractal structure known as the "Devil's staircase". To assess its optical performance, numerical simulations have been performed with a ray tracing program using the Liou-Brennan model eye under polychromatic illumination. The simulated through the focus visual acuity was the merit function employed to test its pupil-dependence and its behavior against decentering. A qualitative assessment of the multifocal intraocular lens (MIOL) was also performed experimentally with an adaptive optics visual simulator. The experimental results confirm our numerical predictions. We found that our MIOL design has a trifocal profile, which is very robust to decentration and has low degree of pupil dependence. It performs better at intermediate distances than at near distances and, for a pupil diameter of 3 mm, it works like an EDoF lens over almost the entire defocus range

    Contribution of mangotoxin to the virulence and epiphytic fitness of Pseudomonas syringae pv. syringae

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    Mangotoxin is an antimetabolite toxin that inhibits ornithine acetyl transferase, a key enzyme in the biosynthetic pathway of ornithine and arginine and recently reported in strains of Pseudomonas syringae pv. syringae (Pss) isolated from mango. Since symptoms on mango tissues are very difficult to reproduce, in this study the role of mangotoxin in Pss virulence was addressed by analyzing the in planta growth and development of disease symptoms on tomato leaflets. Inoculation experiments were carried out following several procedures using the wild-type strain Pss UMAF0158, two Tn5-mutant derivative strains defective in mangotoxin production, and their complemented derivative strains in which mangotoxin production is restored. The ability of the mangotoxin-defective mutants to grow in planta was similar, and their epiphytic survival on the tomato leaf surface identical to the wild-type and complemented strains. However, both the disease index data of incidence and the severity of necrotic symptoms indicated that mangotoxin-defective mutants were less virulent, indicating that mangotoxin is a virulence factor. Furthermore, competition experiments showed that the survival values of the wild-type strain were slightly but significantly higher than those of the mangotoxin-defective mutants, suggesting that mangotoxin production would improve the epiphytic fitness of Pss. [Int Microbiol 2009; 12(2):87-95
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