3,277 research outputs found

    Neutron Transfer reactions induced by 8Li on 9Be

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    Angular distributions for the elastic scattering of 8Li on 9Be and the neutron transfer reactions 9Be(8Li,7Li)10Be and 9Be(8Li,9Li)8Be have been measured with a 27 MeV 8Li radioactive nuclear beam. Spectroscopic factors for 8Li|n=9Li and 7Li|n=8Li bound systems were obtained from the comparison between the experimental differential cross section and finite-range DWBA calculations with the code FRESCO. The spectroscopic factors obtained are compared to shell model calculations and to other experimental values from (d,p) reactions. Using the present values for the spectroscopic factor, cross sections for the direct neutron-capture reactions 7Li(n,g)8Li and 8Li(n,g)9Li were calculated in the framework of a potential model.Comment: 24 pages, 8 Figures, submitted as regular article to PR

    Nanoscale ear drum: Graphene based nanoscale sensors

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    The difficulty in determining the mass of a sample increases as its size diminishes. At the nanoscale, there are no direct methods for resolving the mass of single molecules or nanoparticles and so more sophisticated approaches based on electromechanical phenomena are required. More importantly, one demands that such nanoelectromechanical techniques could provide not only information about the mass of the target molecules but also about their geometrical properties. In this sense, we report a theoretical study that illustrates in detail how graphene membranes can operate as nanoelectromechanical mass-sensor devices. Wide graphene sheets were exposed to different types and amounts of molecules and molecular dynamic simulations were employed to treat these doping processes statistically. We demonstrate that the mass variation effect and information about the graphene-molecule interactions can be inferred through dynamical response functions. Our results confirm the potential use of graphene as mass detector devices with remarkable precision in estimating variations in mass at molecular scale and other physical properties of the dopants

    Remote sensing detection of nutrient uptake in vineyards using narrow-band hyperspectral imagery

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    This manuscript delves further into the assessment of narrow-band vegetation indices derived from hyperspectral imagery acquired at 1 m spatial resolution with the Compact Airborne Spectrographic Imager (CASI). Narrow-band indices proposed in this study were assessed as indicators of biochemical and structural parameters in Vitis vinifera L., observing their relationships with foliar variables such as N, P, K, Ca, Fe, Mg and chlorophyll a+b concentration (Ca+b). Hyperspectral indices were assessed to study their capability for vegetation condition monitoring as a function of fertilization treatments applied (basically extracts of Ascophyllum nodosum seaweed and chelates), showing associations with field variables. Narrow-band vegetation indices displayed sensitivity to vineyard growth and condition as a function of seaweed fertilization and other supplementary mineral correctors, such as chelates. This work shows the interest of using new narrow-band hyperspectral remote sensing indices for vineyard monitoring due to their potential to indicate physiological condition.

    Observational constraints on holographic dark energy with varying gravitational constant

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    We use observational data from Type Ia Supernovae (SN), Baryon Acoustic Oscillations (BAO), Cosmic Microwave Background (CMB) and observational Hubble data (OHD), and the Markov Chain Monte Carlo (MCMC) method, to constrain the cosmological scenario of holographic dark energy with varying gravitational constant. We consider both flat and non-flat background geometry, and we present the corresponding constraints and contour-plots of the model parameters. We conclude that the scenario is compatible with observations. In 1σ\sigma we find ΩΛ0=0.72−0.03+0.03\Omega_{\Lambda0}=0.72^{+0.03}_{-0.03}, Ωk0=−0.0013−0.0040+0.0130\Omega_{k0}=-0.0013^{+0.0130}_{-0.0040}, c=0.80−0.14+0.19c=0.80^{+0.19}_{-0.14} and ΔG≡G′/G=−0.0025−0.0050+0.0080\Delta_G\equiv G'/G=-0.0025^{+0.0080}_{-0.0050}, while for the present value of the dark energy equation-of-state parameter we obtain w0=−1.04−0.20+0.15w_0=-1.04^{+0.15}_{-0.20}.Comment: 12 pages, 2 figures, version published in JCA

    Observational Constraints to Ricci Dark Energy Model by Using: SN, BAO, OHD, fgas Data Sets

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    In this paper, we perform a global constraint on the Ricci dark energy model with both the flat case and the non-flat case, using the Markov Chain Monte Carlo (MCMC) method and the combined observational data from the cluster X-ray gas mass fraction, Supernovae of type Ia (397), baryon acoustic oscillations, current Cosmic Microwave Background, and the observational Hubble function. In the flat model, we obtain the best fit values of the parameters in 1σ,2σ1\sigma, 2\sigma regions: Ωm0=0.2927−0.0323−0.0388+0.0420+0.0542\Omega_{m0}=0.2927^{+0.0420 +0.0542}_{-0.0323 -0.0388}, α=0.3823−0.0418−0.0541+0.0331+0.0415\alpha=0.3823^{+0.0331 +0.0415}_{-0.0418 -0.0541}, Age/Gyr=13.48−0.16−0.21+0.13+0.17Age/Gyr=13.48^{+0.13 +0.17}_{-0.16 -0.21}, H0=69.09−2.37−3.39+2.56+3.09H_0=69.09^{+2.56 +3.09}_{-2.37 -3.39}. In the non-flat model, the best fit parameters are found in 1σ,2σ1\sigma, 2\sigma regions:Ωm0=0.3003−0.0371−0.0423+0.0367+0.0429\Omega_{m0}=0.3003^{+0.0367 +0.0429}_{-0.0371 -0.0423}, α=0.3845−0.0474−0.0523+0.0386+0.0521\alpha=0.3845^{+0.0386 +0.0521}_{-0.0474 -0.0523}, Ωk=0.0240−0.0130−0.0153+0.0109+0.0133\Omega_k=0.0240^{+0.0109 +0.0133}_{-0.0130 -0.0153}, Age/Gyr=12.54−0.37−0.49+0.51+0.65Age/Gyr=12.54^{+0.51 +0.65}_{-0.37 -0.49}, H0=72.89−3.05−3.72+3.31+3.88H_0=72.89^{+3.31 +3.88}_{-3.05 -3.72}. Compared to the constraint results in the ΛCDM\Lambda \textmd{CDM} model by using the same datasets, it is shown that the current combined datasets prefer the ΛCDM\Lambda \textmd{CDM} model to the Ricci dark energy model.Comment: 12 pages, 3 figure
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