5,574 research outputs found

    An alternative methodology to predict aging effects on the mechanical properties of glass fiber reinforced cement (GRC)

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    The effect of three different aging methods (immersion in hot water, freeze–thaw cycles and wet–dry cycles) on the mechanical properties of GRC were studied and compared. Test results showed that immersion in hot water may be an unreliable method for modified GRC formulations, with it being in probability a very harmful procedure. A new aging method, mixing freeze–thaw cycles and wet–dry cycles, seems to be the most accurate simulation of weather conditions that produce a noticeable change in GRC mechanical properties. Future work should be carried out to find a correlation between real weather and the proposed aging method

    Impact of introducing ecoinnovation measures on productivity in transport sector companies

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    The transport and storage sector, like other sectors of the Spanish economy, is experiencing the effects of the current economic crisis. The Annual Services Survey prepared by the Spanish National Institute of Statistics (INE) shows that between 2008 and 2013 there was an 11.9% reduction in turnover and an 18.3% reduction in paid workers in companies in sector. However, in the same period, there was a 7.8% increase in labour productivity. The main aim of this study was to determine the impact of factors related to innovation and the environment, among others, on labour productivity in the Spanish transport and storage sector. Few studies are available on this topic, which is most likely due to the scant statistical information available for the sector analysed. The structural analysis model used in this study was an extended version of the wellknown Cobb‐Douglas production function applied to data obtained from the Technological Innovation Panel (PITEC). PITEC is a panel type database (for 2003‐2013), which was developed jointly by the Spanish National Institute of Statistics (INE) and the Spanish Foundation for Science and Technology.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Dynamic transition in Landau-Zener-St\"uckelberg interferometry of dissipative systems: the case of the flux qubit

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    We study Landau-Zener-Stuckelberg (LZS) interferometry in multilevel systems coupled to an Ohmic quantum bath. We consider the case of superconducting flux qubits driven by a dc+ac magnetic fields, but our results can apply to other similar systems. We find a dynamic transition manifested by a symmetry change in the structure of the LZS interference pattern, plotted as a function of ac amplitude and dc detuning. The dynamic transition is from a LZS pattern with nearly symmetric multiphoton resonances to antisymmetric multiphoton resonances at long times (above the relaxation time). We also show that the presence of a resonant mode in the quantum bath can impede the dynamic transition when the resonant frequency is of the order of the qubit gap. Our results are obtained by a numerical calculation of the finite time and the asymptotic stationary population of the qubit states, using the Floquet-Markov approach to solve a realistic model of the flux qubit considering up to 10 energy levels.Comment: One new figure added. Final version to be published in PR

    Top-antitop resonance searches beyond 1 TeV

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    We perform a general parton level analysis for the search of heavy resonant states in the production of top-antitop pairs at the LHC with an integrated luminosity of 30 fb^-1. We assume the existence of resonances that only couple to quarks and propose kinematic cuts in order to increase the amount of events produced through quark-annihilation. We study the interplay between different variables and their impact on the purity of the selected sample. We make focus on the longitudinal (β\beta) and transverse (pTp_T) momentum of the top-antitop pair, and the scattering angle (θ\theta) in the center of mass reference frame. We observe that β\beta is replaced by θ\theta as a suitable discriminating variable of quark-annihilation processes for invariant masses above 1 TeV. Finally, we illustrate the analysis with a gluon resonance of 1.5 TeV and show the improvement in the sensitivity of the signal when cuts on θ\theta are imposed.Comment: 19 pages and 6 figure

    An integrative approach for modeling and simulation of Heterocyst pattern formation in Cyanobacteria strands

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    A comprehensive approach to cellular differentiation in cyanobacteria is developed. To this aim, the process of heterocyst cell formation is studied under a systems biology point of view. By relying on statistical physics techniques, we translate the essential ingredients and mechanisms of the genetic circuit into a set of differential equations that describes the continuous time evolution of combined nitrogen, PatS, HetR and NtcA concentrations. The detailed analysis of these equations gives insight into the single cell dynamics. On the other hand, the inclusion of diffusion and noisy conditions allows simulating the formation of heterocysts patterns in cyanobacteria strains. The time evolution of relevant component concentrations are calculated allowing for a comparison with experiments. Finally, we discuss the validity and the possible improvements of the model.Comment: 20 pages (including the supporting information), 8 figure

    Curvature as a Measure of the Thermodynamic Interaction

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    We present a systematic and consistent construction of geometrothermodynamics by using Riemannian contact geometry for the phase manifold and harmonic maps for the equilibrium manifold. We present several metrics for the phase manifold that are invariant with respect to Legendre transformations and induce thermodynamic metrics on the equilibrium manifold. We review all the known examples in which the curvature of the thermodynamic metrics can be used as a measure of the thermodynamic interaction
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