1,202 research outputs found

    Flavor constraints on electroweak ALP couplings

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    We explore the signals of axion-like particles (ALPs) in flavor-changing neutral current (FCNC) processes. The most general effective linear Lagrangian for ALP couplings to the electroweak bosonic sector is considered, and its contribution to FCNC decays is computed up to one-loop order. The interplay between the different couplings opens new territory for experimental exploration, as analyzed here in the ALP mass range 0<ma≲50<m_a \lesssim 5 GeV. When kinematically allowed, K→πννˉK\to \pi \nu \bar{\nu} decays provide the most stringent constraints for channels with invisible final states, while BB-meson decays are more constraining for visible decay channels, such as displaced vertices in B→K(∗)μ+μ−B\to K^{(\ast)} \mu^+ \mu^- data. The complementarity with collider constraints is discussed as well.Comment: 12 pages, 6 figure

    The Axion and the Goldstone Higgs

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    We consider the renormalizable SO(5)/SO(4)SO(5)/SO(4) σ\sigma-model, in which the Higgs particle has a pseudo-Nambu-Goldstone boson character, and explore what the minimal field extension required to implement the Peccei-Quinn symmetry (PQ) is, within the partial compositeness scenario. It turns out that the minimal model does not require the enlargement of the exotic fermionic sector, but only the addition of a singlet scalar: it is sufficient that the exotic fermions involved in partial compositeness and the singlet scalar become charged under Peccei-Quinn transformations. We explore the phenomenological predictions for photonic signals in axion searches for all models discussed. Because of the constraints imposed on the exotic fermion sector by the Standard Model fermion masses, the expected range of allowed axion-photon couplings turns out to be generically narrowed with respect to that of standard invisible axion models, impacting the experimental quest.Comment: 31 pages, 2 Figures. Description improved, results unchange

    Effective coping with cyberbullying in boys and girls: the mediating role of self-awareness, responsible decision-making, and social support

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    There is sufficient evidence on the negative consequences of cyberbullying victimisation depending on the coping styles. Social support seeking is among the most effective strategies for coping with cybervictimisation, but it is scarcely used. The robust Maximum Likelihood (ML) method was used to test the potential mediating role of individual (self-awareness, and responsible decision-making) and contextual variables (self-perceived parental and peer support) in the relationship between cybervictimisation and social support seeking in boys and girls. This cross-sectional study collected data from 1,276 Spanish secondary school students (51.2% boys, 48.8% girls) aged 11-18 (M = 13.88, SD = 1.42). Structural equation modelling (SEM) results pointed out responsible decision-making and self-perceived parental support as relevant mediating factors for girls. By contrast, the model was not significant for boys. These findings highlight the importance of both individual and contextual variables in helping adolescents cope with cyberaggressions, considering gender differences

    Reliability evaluation of III-V concentrator solar cells

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    Concentrator solar cells have been proposed as an interesting way of reducing the cost of photovoltaic electricity. However, in order to compete with conventional solar modules it is necessary not only to reduce costs but also to evaluate and increase the present reliability. Concentrator solar cells work at higher temperature, solar radiation and current stress than conventional solar cells and a carefully reliability analysis is needed. In this paper a reliability analysis procedure, that is being developed, is presented

    Regulation of Ace2-dependent genes requires components of the PBF complex in schizosaccharomyces pombe

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    The division cycle of unicellular yeasts is completed with the activation of a cell separation program that results in the dissolution of the septum assembled during cytokinesis between the 2 daughter cells, allowing them to become independent entities. Expression of the eng1+ and agn1+ genes, encoding the hydrolytic enzymes responsible for septum degradation, is activated at the end of each cell cycle by the transcription factor Ace2. Periodic ace2+ expression is regulated by the transcriptional complex PBF (PCB Binding Factor), composed of the forkhead-like proteins Sep1 and Fkh2 and the MADS box-like protein Mbx1. In this report, we show that Ace2-dependent genes contain several combinations of motifs for Ace2 and PBF binding in their promoters. Thus, Ace2, Fkh2 and Sep1 were found to bind in vivo to the eng1+ promoter. Ace2 binding was coincident with maximum level of eng1+ expression, whereas Fkh2 binding was maximal when mRNA levels were low, supporting the notion that they play opposing roles. In addition, we found that the expression of eng1+ and agn1+ was differentially affected by mutations in PBF components. Interestingly, agn1+ was a major target of Mbx1, since its ectopic expression resulted in the suppression of Mbx1 deletion phenotypes. Our results reveal a complex regulation system through which the transcription factors Ace2, Fkh2, Sep1 and Mbx1 in combination control the expression of the genes involved in separation at the end of the cell division cycle

    Acoustic properties of agroforestry waste orange pruning fibers reinforced polypropylene composites as an alternative to laminated gypsum boards

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    The present paper investigates the acoustic properties of natural fiber reinforced composites. Fibers from orange tree pruning were obtained and subject to different treatments in order to obtain mechanical, thermomechanical and chemi-thermomechanical pulps. These pulps were used as reinforcement for a polypropylene matrix. The obtained composite materials were submitted to acoustical tests in an impedance tubes device. The transmission losses obtained against the fiber content were obtained and discussed. Latter it was researched the influence of the fiber treatments on the soundproof characteristics. A numerical method was used to preview the acoustic insulation of the materials against the sound frequency. Finally the results were compared with that of the most usual lightweight soundproof solutions. (C) 2014 Elsevier Ltd. All rights reserved.Reixach, R.; Rey Tormos, RMD.; Alba Fernández, J.; Arbat, G.; Espinach, FX.; Mutjé, P. (2015). Acoustic properties of agroforestry waste orange pruning fibers reinforced polypropylene composites as an alternative to laminated gypsum boards. Construction and Building Materials. 77:124-129. doi:10.1016/j.conbuildmat.2014.12.041S1241297

    Small-sized reverberation chamber for the measurement of sound absorption

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    [ES] Cámara reverberante de tamaño reducido para medidas de la absorción sonora. En este trabajo se muestra el diseño, construcción, calibración y automatización de una cámara reverberante para pequeñas muestras. Se ha buscado un equilibro entre la reducción de tamaño de las muestras para disminuir los costes de fabricación de materiales, y el volumen adecuado que permita obtener valores fiables a determinadas frecuencias. La cámara reverberante construida tiene 1.12 m3 de volumen y permite la medida de muestras de 0.3 m2. La colocación de difusores para aumentar el grado de difusión, y la automatización de las medidas, disminuyen los errores de ensayo. Se muestran también diferentes campañas comparativas de medidas en la cámara reverberante para pequeñas muestras y en la cámara normalizada. Puede verse un buen grado de ajuste entre ambas dentro del rango de frecuencias válido. Por tanto, se muestra un pequeño laboratorio que permite comparar muestras y tomar decisiones, antes de realizar la fabricación de grandes tamaños.[EN] This paper presents the design, construction, calibration and automation of a reverberation chamber for small samples. A balance has been sought between reducing sample size, to reduce the manufacturing costs of materials, and finding the appropriate volume of the chamber, to obtain reliable values at high and mid frequencies. The small-sized reverberation chamber, that was built, has a volume of 1.12 m3 and allows for the testing of samples of 0.3 m2. By using diffusers, to improve the diffusion degree, and automating measurements, we were able to improve the reliability of the results, thus reducing test errors. Several comparison studies of the measurements of the small-sized reverberation chamber and the standardised reverberation chamber are shown, and a good degree of adjustment can be seen between them, within the range of valid frequencies. This paper presents a small laboratory for comparing samples and making decisions before the manufacturing of larger sizes.This project involved the contribution of the European Union’s financial instrument, LIFE: ‘LIFE 09 ENV/ES/461: Demonstrative solutions to reduce noise pollution in industrial, using finishing technologies in textile materials’ and that of the European project ‘WOOL4BUILD ECO/13/630249/SI2.681252, CIP-ECO-INNOVATION: Improved isolation material for eco-building based on natural wool’.Rey Tormos, RMD.; Alba Fernández, J.; Bertó Carbó, L.; Gregori, A. (2017). Small-sized reverberation chamber for the measurement of sound absorption. Materiales de Construcción. 67(328):1-9. doi:10.3989/mc.2017.07316S1967328Del Rey, R., Alba, J., Ramis, J., & Sanchís, V. J. (2011). Nuevos materiales absorbentes acústicos obtenidos a partir de restos de botellas de plástico. Materiales de Construcción, 61(304), 547-558. doi:10.3989/mc.2011.59610Maderuelo-Sanz, R., Nadal-Gisbert, A. V., Crespo-Amorós, J. E., & Parres-García, F. (2012). A novel sound absorber with recycled fibers coming from end of life tires (ELTs). Applied Acoustics, 73(4), 402-408. doi:10.1016/j.apacoust.2011.12.001Rey, R. del, Alba, J., Arenas, J. P., & Sanchis, V. J. (2012). An empirical modelling of porous sound absorbing materials made of recycled foam. Applied Acoustics, 73(6-7), 604-609. doi:10.1016/j.apacoust.2011.12.009Fatima, S., & Mohanty, A. R. (2011). Acoustical and fire-retardant properties of jute composite materials. Applied Acoustics, 72(2-3), 108-114. doi:10.1016/j.apacoust.2010.10.005Ramis, J., Alba, J., Del Rey, R., Escuder, E., & Sanchís, V. J. (2010). Nuevos materiales absorbentes acústicos basados en fibra de kenaf. Materiales de Construcción, 60(299), 133-143. doi:10.3989/mc.2010.50809Ramis, J., Del Rey, R., Alba, J., Godinho, L., & Carbajo, J. (2014). A model for acoustic absorbent materials derived from coconut fiber. Materiales de Construcción, 64(313), e008. doi:10.3989/mc.2014.00513Díaz, C., Jiménez, M., Navacerrada, M. A., & Pedrero, A. (2010). Propiedades acústicas de los paneles de carrizo. Materiales de Construcción, 62(305), 55-66. doi:10.3989/mc.2010.60510Arenas, J. P., Rebolledo, J., Del Rey, R., & Alba, J. (2014). Sound Absorption Properties of Unbleached Cellulose Loose-Fill Insulation Material. BioResources, 9(4). doi:10.15376/biores.9.4.6227-624011. Bulent, E.; Aykut, K.; Haluk, K. (2012). Improving Sound Absorption Property of Polyurethane Foams by Adding Tea-Leaf Fibers. Arch. Acoust. 37 [4] 515-520.16. Hernández, D.; Liu, E.J.; Huang, J.H.; Liu, Y.C. (2015). Design and Construction of a Small Reverberation Chamber Applied to Absorption and Scattering Acoustic Measurements. Advanced Materials Research. 1077. 197–202.Bradley, D. T., Müller-Trapet, M., Adelgren, J., & Vorländer, M. (2014). Effect of boundary diffusers in a reverberation chamber: Standardized diffuse field quantifiers. The Journal of the Acoustical Society of America, 135(4), 1898-1906. doi:10.1121/1.486629123. Skålevik, M. (2011). Schroeder Frequency revisited. International Congress Forum Acustikum – Aalborg, Denmark – 2011

    Regeneration niche of the Canarian juniper : the role of adults, shrubs and environmental conditions

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    Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch

    Goitre and Iodine Deficiency in Europe

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    The prevalence of endemic iodine-deficiency goitre in Europe has been reduced in many areas by the introduction of iodination programmes. Recent reports, however, show that goitre remains a significant problem and that its prevalence has not decreased in a number of European countries. Hetzel1 has pointed out that the high global prevalence of iodine-deficiency disorders could be eradicated within 5-10 years by introduction of an iodised salt programme. The current World Health Organisation recommendations for iodine intake are between 150 and 300 μg/da
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