323 research outputs found

    Nonleptonic two-body B-decays including axial-vector mesons in the final state

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    We present a systematic study of exclusive charmless nonleptonic two-body B decays including axial-vector mesons in the final state. We calculate branching ratios of B\to PA, VA and AA decays, where A, V and P denote an axial-vector, a vector and a pseudoscalar meson, respectively. We assume naive factorization hypothesis and use the improved version of the nonrelativistic ISGW quark model for form factors in B\to A transitions. We include contributions that arise from the effective \Delta B=1 weak Hamiltonian H_{eff}. The respective factorized amplitude of these decays are explicitly showed and their penguin contributions are classified. We find that decays B^-to a_1^0\pi^-,\barB^0\to a_1^{\pm}\pi^{\mp}, B^-\to a_1^-\bar K^0, \bar B^0\to a_1^+K^-, \bar B^0\to f_1\bar K^0, B^-\to f_1K^-, B^-\to K_1^-(1400)\etap, B^-\to b_1^-\bar K^{0}, and \bar B^0\to b_1^+\pi^-(K^-) have branching ratios of the order of 10^{-5}. We also study the dependence of branching ratios for B \to K_1P(V,A) decays (K_1=K_1(1270),K_1(1400)) with respect to the mixing angle between K_A and K_B.Comment: 28 pages, 2 tables and one reference added, notation changed in appendices, some numerical results and abstract correcte

    Climate-risk materiality and firm risk

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    Managers are required to disclose material climate risk in Form 10-K, but their decision whether or not to disclose is confounded by the lack of consensus on whether climate risk is material to the firms, as well as uncertainty about enforcement of disclosure regulations. Using the SASB Materiality Map™ to proxy for market expectations of climate risk materiality, we test whether the association between disclosing climate risk in 10-Ks and firm risk (proxied by cost of equity (COE)) varies with market expectations of climate risk materiality. Using S&P 500 firms’ decisions whether to disclose climate risk in Form 10-K for 2008 to 2016, we find that disclosing firms’ COE is 27 bps lower than nondisclosing firms’ COE. In industries where the market expects climate risk to be material, disclosing firms’ COE is 50 bps lower than nondisclosing firms’, while in industries where the market does not expect climate risk to be material, disclosing firms’ COE is 23 bps lower than nondisclosing firms’. Our results indicate that markets use expectations of climate risk materiality to infer the credibility of managers’ climate risk disclosure decisions. Our research contributes to policy-making on climate risk disclosures in regulatory filings and informs the debate around the costs and benefits of the SEC’s current proposal to enhance climate risk disclosures

    Characterization of competing distortions in YFe2O4

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    We report the structural changes of three YFe2O4-δ (δ<0.1) specimens using high resolution synchrotron x-ray powder diffraction between 80 and 300 K. All samples adopt a rhombohedral cell at room temperature (space group R3m). This cell becomes unstable for the three samples on cooling, and the oxygen-poor specimen (δ∼0.1) shows a single transition at 240 K. The nearly stoichiometric (δ≤0.03) compounds exhibit two structural transitions with decreasing temperature at about 240 and 200 K. Each transition is revealed by an anomaly in the heat capacity measurements and a jump in the electric resistivity. Below 240 K, a strong splitting of some diffraction peaks is accompanied by the occurrence of superstructure peaks that follow the propagation vector k=(1/7,-2/7,9/7). The cell symmetry is then triclinic, and the structural transition is characterized by an expansion of the c axis coupled to a contraction of the other two lattice parameters. There are 49 nonequivalent sites for Fe atoms with a maximum charge disproportionation of ∼0.5e-. Upon cooling at 200 K, the previous superstructure peaks begin to vanish, and finally they are replaced by a new set of superstructure peaks following the propagation vector k=(1/4,1/2,1/4) with respect to the rhombohedral cell. The transition is also reflected in sudden changes in the lattice parameters that seem to smooth the changes observed in the previous transition. The new cell is also triclinic, and there are 48 nonequivalent Fe sites with a maximum charge disproportionation of ∼0.7e-. Both phases coexist in a wide temperature range because this second transition is not completed at 80 K. A symmetry mode analysis indicates a complicated pattern for the charge distribution in the Fe sublattice of both distorted structures but clearly discard any bimodal distribution of only two types of Fe cations. Therefore, the sharp jumps in the electric resistivity at the phase transitions are clearly correlated with two different structural changes. Finally, the oxygen stoichiometry seems to be a key factor in the stabilization of the different distorted structures.We are thankful for financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) (Projects No. MAT2012-38213-C02-1-2 and No. MAT2015-68760-C2-1-2, cofunded by the European Regional Development Fund [ERDF] allocated by the European Union) and Diputacion General de Aragón (DGA, project E69).Peer Reviewe

    Effect of carob (Ceratonia siliqua L.) seed in broiler chick diets on nutrient digestibility and intestinal viscosity.

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    La inclusión de garrofín a niveles de 60 (ración CS-60) y 90 g/kg (ración CS-90) en una ración referencia produjo una marcada (P<O.O1) disminución de la utilización de los nutrientes. La reducción en la digestibilidad aparente de la proteína bruta y de la grasa bruta fue del 12.7 y 20.9% en la ración CS-60, y del 29.5 y 23.8% en la ración CS-90, respectivamente. La energía metabolizable aparente disminuyó siguiendo una tendencia similar a la observada en la digestibilidad de la grasa bruta. La viscosidad de la digesta en el yeyuno se incrementó acusadamente por la presencia de garrofín en la ración, lo que podría explicar la mayoría de los resultados obtenidos en este estudio.// lnclusion of carob seed at levels of 60 (CS-60 diet) and 90 glkg (CS-90 diet) in a reference diet caused a marked (P<O.Ol) depression in the utilization of nutrients. The reduction in the apparent digestibility of crude protejo and crude fat was 12.7 and 20.9% for CS-60 diet, and 29.5 and 23.8% for CS-90 diet, respectively. The apparent metabolizable energy value followed a similar depressing trend than that observed for crude fat digestibility. Viscosity of the jejunal digesta was drastically increased by the presence of carob seed in the diet, and it might explain most of the results obtained in this study

    Analycity and smoothing effect for the coupled system of equations of Korteweg - de Vries type with a single point singularity

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    We study that a solution of the initial value problem associated for the coupled system of equations of Korteweg - de Vries type which appears as a model to describe the strong interaction of weakly nonlinear long waves, has analyticity in time and smoothing effect up to real analyticity if the initial data only has a single point singularity at $x=0.

    Characterization of Microstructural and Mechanical Properties of 17-4 PH Stainless Steel by Cold Rolled and Machining vs. DMLS Additive Manufacturing

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    The 17-4 PH stainless steel is widely used in the aerospace, petrochemical, chemical, food, and general metallurgical industries. The present study was conducted to analyze the mechanical properties of two types of 17-4 PH stainless steel—commercial cold-rolled and direct metal laser sintering (DMLS) manufactured. This study employed linear and nonlinear tensile FEM simulations, combined with various materials characterization techniques such as tensile testing and nanoindentation. Moreover, microstructural analysis was performed using metallographic techniques, optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results on the microstructure for 17-4 PH DMLS stainless steel reveal the layers of melting due to the laser process characterized by complex directional columnar structures parallel to the DMLS build direction. The mechanical properties obtained from the simple tension test decreased by 17% for the elastic modulus, 7.8% for the yield strength, and 7% for the ultimate strength for 17-4 PH DMLS compared with rolled 17-4 PH stainless steel. The FEM simulation using the experimental tension test data revealed that the 17-4 PH DMLS stainless steel experienced a decrease in the yield strength of ~8% and in the ultimate strength of ~11%. A reduction of the yield strength of the material was obtained as the grain size increased

    The Chemical Evolution Carousel of Spiral Galaxies : Azimuthal Variations of Oxygen Abundance in NGC1365

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    19 pages, 13 figures. Accepted to ApJThe spatial distribution of oxygen in the interstellar medium of galaxies is the key to understanding how efficiently metals that are synthesized in massive stars can be redistributed across a galaxy. We present here a case study in the nearby spiral galaxy NGC1365 using 3D optical data obtained in the TYPHOON Program. We find systematic azimuthal variations of the HII region oxygen abundance imprinted on a negative radial gradient. The 0.2 dex azimuthal variations occur over a wide radial range of 0.3 to 0.7 R25 and peak at the two spiral arms in NGC1365. We show that the azimuthal variations can be explained by two physical processes: gas undergoes localized, sub-kpc scale self-enrichment when orbiting in the inter-arm region, and experiences efficient, kpc scale mixing-induced dilution when spiral density waves pass through. We construct a simple chemical evolution model to quantitatively test this picture and find that our toy model can reproduce the observations. This result suggests that the observed abundance variations in NGC1365 are a snapshot of the dynamical local enrichment of oxygen modulated by spiral-driven, periodic mixing and dilution.Peer reviewedFinal Published versio

    Extreme and long-term drought in the La Plata Basin: event evolution and impact assessment until September 2022

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    The current drought conditions across the Parana-La Plata Basin (LPB) in Brazil-Argentina have been the worst since 1944. While this area is characterized by a rainy season with a peak from October to April, the hydrological year 2020-2021 was very deficient in rainfall, and the situation extended into the 2021-2022 hydrological year. Below-normal rainfall was dominant in south-eastern Brazil, northern Argentina, Paraguay, and Uruguay, suggesting a late onset and weaker South American Monsoon and the continuation of drier conditions since 2021. In fact, in 2021 Brazilian south and south-east regions faced their worst droughts in nine decades, raising the spectre of possible power rationing given the grid dependence on hydroelectric plants. The Paraná-La Plata Basin drought induced damages to agriculture and reduced crop production, including soybeans and maize, with effects on global crop markets. The drought situation continued in 2022 in the Pantanal region. Dry meteorological conditions are still present in the region at the end of September 2022 with below-average precipitation anomalies. Soil moisture anomaly and vegetation conditions are worst in the lower part of the La Plata Basin, in the southern regions. Conversely, upper and central part of the basin show partial and temporary recovery

    Real-time Soundprism

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    [EN] This paper presents a parallel real-time sound source separation system for decomposing an audio signal captured with a single microphone in so many audio signals as the number of instruments that are really playing. This approach is usually known as Soundprism. The application scenario of the system is for a concert hall in which users, instead of listening to the mixed audio, want to receive the audio of just an instrument, focusing on a particular performance. The challenge is even greater since we are interested in a real-time system on handheld devices, i.e., devices characterized by both low power consumption and mobility. The results presented show that it is possible to obtain real-time results in the tested scenarios using an ARM processor aided by a GPU, when this one is present.This work has been supported by the "Ministerio de Economia y Competitividad" of Spain and FEDER under projects TEC2015-67387-C4-{1,2,3}-R.Muñoz-Montoro, AJ.; Ranilla, J.; Vera-Candeas, P.; Combarro, EF.; Alonso-Jordá, P. (2019). Real-time Soundprism. The Journal of Supercomputing. 75(3):1594-1609. https://doi.org/10.1007/s11227-018-2703-0S15941609753Alonso P, Cortina R, Rodríguez-Serrano FJ, Vera-Candeas P, Alonso-González M, Ranilla J (2017) Parallel online time warping for real-time audio-to-score alignment in multi-core systems. J Supercomput 73:126. https://doi.org/10.1007/s11227-016-1647-5Carabias-Orti JJ, Cobos M, Vera-Candeas P, Rodríguez-Serrano FJ (2013) Nonnegative signal factorization with learnt instrument models for sound source separation in close-microphone recordings. 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