969 research outputs found

    Effect of the mycelium, diffused substances and extracts of the fungus Cladosporium herbarum (Pers.) link on the in vitro and in vivo growth of grapevine (Vitis vinifera L.) cv. Cabernet Sauvignon

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    The fungus Cladosporium herbarum (Pers.) Link was cocultured with plantlets of grapevine (Vitis vinifera L.) cv. Cabernet Sauvignon in vitro and ex vitro. The mycelium of the fungus stimulates growth of the plantlets. This is probably exerted by the diffusion of some growth and/or nutritional substance(s) of unknown chemical nature. In another trial filtrates of the fungus and fungus extracts were added to the culture medium of grapevine plantlets in different concentrations. The fungus extracts stimulated growth of plantlets at low concentrations and inhibited growth at high concentrations

    XUV Opacity of Aluminum between the Cold-Solid to Warm-Plasma Transition

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    We present calculations of the free-free XUV opacity of warm, solid-density aluminum at photon energies between the plasma frequency at 15 eV and the L-edge at 73 eV, using both density functional theory combined with molecular dynamics and a semi-analytical model in the RPA framework with the inclusion of local field corrections. As the temperature is increased from room temperature to 10 eV, with the ion and electron temperatures equal, we calculate an increase in the opacity in the range over which the degree of ionization is constant. The effect is less pronounced if only the electron temperature is allowed to increase. The physical significance of these increases is discussed in terms of intense XUV-laser matter interactions on both femtosecond and picosecond time-scales.Comment: 4 pages, 3 figure

    Quantum Gravity Effects in Black Holes at the LHC

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    We study possible back-reaction and quantum gravity effects in the evaporation of black holes which could be produced at the LHC through a modification of the Hawking emission. The corrections are phenomenologically taken into account by employing a modified relation between the black hole mass and temperature. The usual assumption that black holes explode around 11 TeV is also released, and the evaporation process is extended to (possibly much) smaller final masses. We show that these effects could be observable for black holes produced with a relatively large mass and should therefore be taken into account when simulating micro-black hole events for the experiments planned at the LHC.Comment: 14 pages, 8 figures, extended version of hep-ph/0601243 with new analysis of final products, final version accepted for publication in J. Phys.

    Beyond the hypothesis of boundedness for the random coefficient of Airy, Hermite and Laguerre differential equations with uncertainties

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    [EN] In this work, we study the full randomized versions of Airy, Hermite and Laguerre differential equations, which depend on a random variable appearing as an equation coefficient as well as two random initial conditions. In previous contributions, the mean square stochastic solutions to the aforementioned random differential equations were constructed via the Frobenius method, under the assumption of exponential growth of the absolute moments of the equation coefficient, which is equivalent to its essential boundedness. In this paper we aim at relaxing the boundedness hypothesis to allow more general probability distributions for the equation coefficient. We prove that the equations are solvable in the mean square sense when the equation coefficient has finite moment-generating function in a neighborhood of the origin. A thorough discussion of the new hypotheses is included.This work has been supported by the Spanish Ministerio de Economia y Competitividad grant MTM2017-89664-P.Calatayud Gregori, J.; Cortés, J.; Jornet Sanz, M. (2020). Beyond the hypothesis of boundedness for the random coefficient of Airy, Hermite and Laguerre differential equations with uncertainties. Stochastic Analysis and Applications. 38(5):875-885. https://doi.org/10.1080/07362994.2020.1733017S875885385Neckel, T., & Rupp, F. (2013). Random Differential Equations in Scientific Computing. doi:10.2478/9788376560267Villafuerte, L., Braumann, C. A., Cortés, J.-C., & Jódar, L. (2010). Random differential operational calculus: Theory and applications. Computers & Mathematics with Applications, 59(1), 115-125. doi:10.1016/j.camwa.2009.08.061Cortés, J.-C., Jódar, L., Camacho, F., & Villafuerte, L. (2010). Random Airy type differential equations: Mean square exact and numerical solutions. Computers & Mathematics with Applications, 60(5), 1237-1244. doi:10.1016/j.camwa.2010.05.046Calbo, G., Cortés, J.-C., & Jódar, L. (2011). Random Hermite differential equations: Mean square power series solutions and statistical properties. Applied Mathematics and Computation, 218(7), 3654-3666. doi:10.1016/j.amc.2011.09.008Calatayud, J., Cortés, J.-C., & Jornet, M. (2019). Improving the Approximation of the First- and Second-Order Statistics of the Response Stochastic Process to the Random Legendre Differential Equation. Mediterranean Journal of Mathematics, 16(3). doi:10.1007/s00009-019-1338-6Calatayud, J., Cortés, J.-C., Jornet, M., & Villafuerte, L. (2018). Random non-autonomous second order linear differential equations: mean square analytic solutions and their statistical properties. Advances in Difference Equations, 2018(1). doi:10.1186/s13662-018-1848-8Gregori, J., López, J., & Sanz, M. (2018). Some Notes to Extend the Study on Random Non-Autonomous Second Order Linear Differential Equations Appearing in Mathematical Modeling. Mathematical and Computational Applications, 23(4), 76. doi:10.3390/mca23040076Calbo, G., Cortés, J.-C., & Jódar, L. (2010). Mean square power series solution of random linear differential equations. Computers & Mathematics with Applications, 59(1), 559-572. doi:10.1016/j.camwa.2009.06.007Calbo, G., Cortés, J.-C., Jódar, L., & Villafuerte, L. (2010). Analytic stochastic process solutions of second-order random differential equations. Applied Mathematics Letters, 23(12), 1421-1424. doi:10.1016/j.aml.2010.07.011CALBO SANJUÁN, G. (s. f.). Mean Square Analytic Solutions of Random Linear Models. doi:10.4995/thesis/10251/8721Jagadeesan, M. (2017). Simple analysis of sparse, sign-consistent JL. arXiv:1708.02966.Lin, G. D. (2017). Recent developments on the moment problem. Journal of Statistical Distributions and Applications, 4(1). doi:10.1186/s40488-017-0059-2Ernst, O. G., Mugler, A., Starkloff, H.-J., & Ullmann, E. (2011). On the convergence of generalized polynomial chaos expansions. ESAIM: Mathematical Modelling and Numerical Analysis, 46(2), 317-339. doi:10.1051/m2an/2011045Calbo, G., Cortés, J.-C., Jódar, L., & Villafuerte, L. (2011). Solving the random Legendre differential equation: Mean square power series solution and its statistical functions. Computers & Mathematics with Applications, 61(9), 2782-2792. doi:10.1016/j.camwa.2011.03.04

    Li₀.₆[Li₀.₂Sn₀.₈S₂] – a layered lithium superionic conductor

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    One of the key challenges of energy research is finding solid electrolytes with high lithium conductivities comparable to those of liquid electrolytes. In this context, developing new structural families of potential Li+ ion conductors and identifying structural descriptors for fast Li+ ion conduction to occur is key to expand the scope of viable Li+ ion conductors. Here, we report that the layered material Li0.6[Li0.2Sn0.8S2] shows a Li+ ion conductivity comparable to the currently best lithium superionic conductors (LISICONs). Li0.6[Li0.2Sn0.8S2] is composed of layers comprising edge-sharing Li/SnS6 octahedra, interleaved with both tetrahedrally and octahedrally coordinated Li+ ions. Pulsed field gradient (PFG) NMR studies on powder samples show intragrain (bulk) diffusion coefficients DNMR on the order of 10−11 m2 s−1 at room temperature, which corresponds to a conductivity σNMR of 9.3 × 10−3 S cm−1 assuming the Nernst–Einstein equation, thus putting Li0.6[Li0.2Sn0.8S2] en par with the best Li solid electrolytes reported to date. This is in agreement with impedance spectroscopy on powder pellets, showing a conductivity of 1.5 × 10−2 S cm−1. Direct current galvanostatic polarization/depolarization measurements on such samples show negligible electronic contributions (less than 10−9 S cm−1) but indicate significant contact resistance (d.c. conductivity in a reversible cell is 1.2 × 10−4 S cm−1 at 298 K). Our results suggest that the partial occupation of interlayer Li+ positions in this layered material is beneficial for its transport properties, which together with tetrahedrally coordinated Li sites provides facile Li+ ion diffusion pathways in the intergallery space between the covalent Sn(Li)S2 layers. This work therefore points to a generic design principle for new layered Li+ ion conductors based on the controlled depletion of Li+ ions in the interlayer space

    Router-level community structure of the Internet Autonomous Systems

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    The Internet is composed of routing devices connected between them and organized into independent administrative entities: the Autonomous Systems. The existence of different types of Autonomous Systems (like large connectivity providers, Internet Service Providers or universities) together with geographical and economical constraints, turns the Internet into a complex modular and hierarchical network. This organization is reflected in many properties of the Internet topology, like its high degree of clustering and its robustness. In this work, we study the modular structure of the Internet router-level graph in order to assess to what extent the Autonomous Systems satisfy some of the known notions of community structure. We show that the modular structure of the Internet is much richer than what can be captured by the current community detection methods, which are severely affected by resolution limits and by the heterogeneity of the Autonomous Systems. Here we overcome this issue by using a multiresolution detection algorithm combined with a small sample of nodes. We also discuss recent work on community structure in the light of our results

    BPS black holes, the Hesse potential, and the topological string

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    The Hesse potential is constructed for a class of four-dimensional N=2 supersymmetric effective actions with S- and T-duality by performing the relevant Legendre transform by iteration. It is a function of fields that transform under duality according to an arithmetic subgroup of the classical dualities reflecting the monodromies of the underlying string compactification. These transformations are not subject to corrections, unlike the transformations of the fields that appear in the effective action which are affected by the presence of higher-derivative couplings. The class of actions that are considered includes those of the FHSV and the STU model. We also consider heterotic N=4 supersymmetric compactifications. The Hesse potential, which is equal to the free energy function for BPS black holes, is manifestly duality invariant. Generically it can be expanded in terms of powers of the modulus that represents the inverse topological string coupling constant, gsg_s, and its complex conjugate. The terms depending holomorphically on gsg_s are expected to correspond to the topological string partition function and this expectation is explicitly verified in two cases. Terms proportional to mixed powers of gsg_s and gˉs\bar g_s are in principle present.Comment: 28 pages, LaTeX, added comment

    Intrauterine versus post-mortem magnetic resonance in second trimester termination of pregnancy for central nervous system abnormalities

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    Objective: To evaluate if limiting factors of intrauterine magnetic resonance imaging (iuMRI) performed in the early second trimester of pregnancy (19\u201323 weeks) affect its accuracy in comparison to post-mortem MRI (pmMRI) in fetuses that underwent termination of pregnancy (TOP) for central nervous system (CNS) defects. Study design: This is a secondary analysis of a 10 years prospective observational study. Cases of TOP < 23 weeks for CNS malformation that had undergone neurosonography (NSG), iuMRI, pmMRI and autopsy were included. The agreement between iuMRI and pmMRI was calculated. The autopsy represented the gold-standard. Results: Overall, 143 TOPs for fetal congenital anomaly underwent the post-mortem diagnostic protocol. Of these, 31 cases underwent iuMRI and pmMRI for CNS abnormality. Three cases were excluded due to brain autolysis at autopsy. Corpus callosum defects were the most represented (16/28; 57 %). In only one case of posterior fossa defect, pmMRI identified the presence of vermian hypoplasia not diagnosed at iuMRI. In 2 cases (7%), iuMRI added clinically relevant additional findings to NSG, that were posteriorly confirmed by pmMRI. Conclusions: The study shows that, at 19\u201323 weeks and for CNS defects, limiting factors that might influence the performance of iuMRI have little influence on iuMRI accuracy. This finding is particularly important for professionals who work in countries with legal bound for TOP in the early second trimester
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