Corporate blogging in Spanish companies. Design and application of a quality index (ICB)

Blogs have strengthened its position as an online communication tool to increase the dialogue between organizations and their publics, and this thanks to their interactive capacity and easy use. Although blogs didn’t enjoy the popularity and swift penetration of social networks, Spanish companies are gradually incorporating this channel to their Public Relations plans. Thus, it becomes increasingly interesting to develop a quantitative index allowing determining the degree of compliance to excellence criteria. This paper aims to identify the main factors in order to value the quality of a corporate blog, describes the design of the evaluation index and, later, applies this index to study the corporate blogs of the main Spanish companies in order to unveil how they are exploiting its many advantages

Paisaje Vegetal y Espectro Ecológico de dos Municipios Navarros (España)

Tomando como referencia el trabajo de BRAUN BLANQUET y 0. DE BOLOS (1957) sobre el Valle del Ebro, se ha realizado un estudio del paisaje vegetal de Marcilla y Milagro, municipios situados en la Ribera de Navarra. Hemos reconocido comunidades vegetales pertenecientes a 14 clases fitosociológicas. Expresamos nuestros resultados mediante dos perfiles fitotopográficos y un espectro ecológico

Caracterización física y química de ríos de montaña (Tafí del Valle-Tucumán-Argentina)

En este trabajo se estudió durante el ciclo anual 2000-2001, a los ríos Blanquito, Churqui, de La Ovejería, de Las Carreras, Tafí, El Mollar y Los Sosa, ubicados a 2000 msnm en el valle de Tafí (Tucumán-Argentina). El objetivo de esta contribución fue caracterizar e interpretar las variaciones espacio-temporales de los parámetros físicos y químicos en relación con la dinámica hidrológica a la que se encuentran sujetos estos ecosistemas acuáticos y además, comparar la calidad de sus aguas. Las variables físicas y químicas analizadas fueron: oxígeno disuelto (OD), demanda bioquímica de oxígeno (DBO5), iones mayoritarios, compuestos nitrogenados, ortofosfatos y metales pesados. Los resultados muestran que la temperatura varió entre 4.2 y 28 ◦C, el pH fluctuó de neutro a alcalino (6.7-8.7) y la conductividad eléctrica entre 64 y 296 μS/cm. El OD y la DBO5 se mostraron estables, alcanzando máximos valores de 10.1 y 2 mg/l, respectivamente. El agua pudo caracterizarse como bicarbonatada-cálcica dominante. Las concentraciones de N-NO−3 oscilaron entre 0.1 y 0.6 mg/l, el N-NO−2 sólo llegó en el río Churqui a 0.01 mg/l y el N-NH+4 alcanzó valores de 0.8 mg/l. En general los registros de los ortofosfatos fueron inferiores a 0.2 mg/l. Los metales pesados Cu2+ y Fe3+ llegaron a un máximo de 3 mg/l y 1.8 mg/l, respectivamente. Las mayores concentraciones del hierro se presentaron en el río de La Ovejería y de cobre en el río El Mollar, probablemente por contaminación antropogénica. La interpretación de los análisis de componentes principales realizados sobre la matriz de parámetros físicos y químicos, permitió diferenciar a los sistemas lóticos temporal y espacialmente. El componente 1 ordenó a los ríos de acuerdo a los iones mayoritarios predominantes y a la conductividad, lo que podría interpretarse como un eje de mineralización. Los componentes 2 y 3, ordenaron las muestras de invierno y primavera y las de verano y otoño, de acuerdo a la variación cíclica estacional coincidiendo con las condiciones climáticas del área de estudio.In this work, throughout the 2000-2001 annual period, the Blanquito, Churqui, de La Ovejería, de Las Carreras, Tafí, El Mollar and Los Sosa rivers, located at 2000 m above sea level in the Taf'ı Valley (Tucumán-Argentina) were studied. The aim of this paper was not only to characterize and understand the spatial and temporal variations of physical and chemical parameters related to the hydrological dynamics these aquatic ecosystems are subject to, but also to compare the quality of their waters. Physical and chemical variables analysed were: dissolved oxygen (DO), biochemical oxygen demand (BOD5), preponderant ions, nitrogenous compounds, orthophosphates, and heavy metals. Results show that the temperature ranged between 4.2 and 28 ◦C, pH fluctuated from neutral to alkaline (6.7-8.7) and electrical conductivity varied between 64 and 296 μS/cm. DO and BOD5 were stable and reached maximum values of 10.1 and 2 mg/l, respectively. The water could be characterized as mainly bicarbonated-calcic. N-NO−3 concentrations ranged between 0.1 and 0.6 mg/l, N-NO−2 reaching only 0.01 mg/l in the Churqui river, and N-NH+4 reached values of 0.8 mg/l. In general, orthophosphate records were lower than 0.2 mg/l. Maximum values for heavy metals, Cu2 + and Fe3 + were 3 mg/l y 1.8 mg/l, respectively. Iron highest concentrations were found in de La Ovejería river, whereas those for copper were found in El Mollar river, probably due to anthropogenic pollution. The interpretation of the main component analyses carried out on the physical and chemical parameters matrix, allowed to differentiate lotic systems both temporally and spatially. Component 1 ordered the rivers according to both the prevailing ions and conductivity, which could be interpreted as a mineralization axis. Components 2 and 3 ordered the winter and spring, and the summer and autumn samples according to the seasonal cyclic variation, coinciding with the climatic conditions of the area under study

Solving second-order linear differential equations with random analytic coefficients about ordinary points: A full probabilistic solution by the first probability density function

[EN] This paper deals with the approximate computation of the first probability density function of the solution stochastic process to second-order linear differential equations with random analytic coefficients about ordinary points under very general hypotheses. Our approach is based on considering approximations of the solution stochastic process via truncated power series solution obtained from the random regular power series method together with the so-called Random Variable Transformation technique. The validity of the proposed method is shown through several illustrative examples.This work has been partially supported by the Ministerio de Econom ia y Competitividad grant MTM2013-41765-P. Ana Navarro Quiles acknowledges the doctorate scholarship granted by Programa de Ayudas de Investigacion y Desarrollo (PAID), Universitat Politecnica de Valencia.Cortés, J.; Navarro-Quiles, A.; Romero, J.; Roselló, M. (2018). Solving second-order linear differential equations with random analytic coefficients about ordinary points: A full probabilistic solution by the first probability density function. Applied Mathematics and Computation. 331:33-45. https://doi.org/10.1016/j.amc.2018.02.051S334533

Solving fully randomized higher-order linear control differential equations: Application to study the dynamics of an oscillator

This is the peer reviewed version of the following article: Cortés, J-C, Navarro-Quiles, A, Romero, J-V, Roselló, M-D. Solving fully randomized higher-order linear control differential equations: Application to study the dynamics of an oscillator. Comp and Math Methods. 2021; 3:e1163, which has been published in final form at https://doi.org/10.1002/cmm4.1163. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] In this work, we consider control problems represented by a linear differential equation assuming that all the coefficients are random variables and with an additive control that is a stochastic process. Specifically, we will work with controllable problems in which the initial condition and the final target are random variables. The probability density function of the solution and the control has been calculated. The theoretical results have been applied to study, from a probabilistic standpoint, a damped oscillator.European Social Fund, Grant/Award Numbers: GJIDI/2018/A/009, GJIDI/2018/A/010; Spanish Ministerio de Economía, Industria y Competitividad (MINECO), the Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER UE), Grant/Award Number: MTM2017-89664-P.Cortés, J.; Navarro-Quiles, A.; Romero, J.; Roselló, M. (2021). Solving fully randomized higher-order linear control differential equations: Application to study the dynamics of an oscillator. Computational and Mathematical Methods. 3(6):1-15. https://doi.org/10.1002/cmm4.1163S1153

Some results about randomized binary Markov chains: Theory, computing and applications

[EN] This paper is addressed to give a generalization of the classical Markov methodology allowing the treatment of the entries of the transition matrix and initial condition as random variables instead of deterministic values lying in the interval [0,1]. This permits the computation of the first probability density function (1-PDF) of the solution stochastic process taking advantage of the so-called Random Variable Transformation technique. From the 1-PDF relevant probabilistic information about the evolution of Markov models can be calculated including all one-dimensional statistical moments. We are also interested in determining the computation of distribution of some important quantities related to randomized Markov chains (steady state, hitting times, etc.). All theoretical results are established under general assumptions and they are illustrated by modelling the spread of a technology using real data.This work has been partially supported by the Ministerio de Economía y Competitividad [grant MTM2017-89664-P]. Ana Navarro Quiles acknowledges the doctorate scholarship granted by Programa de Ayudas de Investigación y Desarrollo (PAID), Universitat Politècnica de ValènciaCortés, J.; Navarro-Quiles, A.; Romero, J.; Roselló, M. (2020). Some results about randomized binary Markov chains: Theory, computing and applications. International Journal of Computer Mathematics. 97(1-2):141-156. https://doi.org/10.1080/00207160.2018.1440290S141156971-

Probabilistic analysis of random nonlinear oscillators subject to small perturbations via probability density functions: Theory and computing

[EN] We study a class of single-degree-of-freedom oscillators whose restoring function is affected by small nonlinearities and excited by stationary Gaussian stochastic processes. We obtain, via the stochastic perturbation technique, approximations of the main statistics of the steady state, which is a random variable, including the first moments, and the correlation and power spectral functions. Additionally, we combine this key information with the principle of maximum entropy to construct approximations of the probability density function of the steady state. We include two numerical examples where the advantages and limitations of the stochastic perturbation method are discussed with regard to certain general properties that must be preservedThis work has been supported by the Spanish Ministerio de Economia, Industria y Competitividad (MINECO), the Agencia Estatal de Investigacion (AEI), and Fondo Europeo de Desarrollo Regional (FEDER UE) Grant PID2020-115270GB-I00. The authors express their deepest thanks and respect to the reviewers for their valuable commentsCortés, J.; López-Navarro, E.; Romero, J.; Roselló, M. (2021). Probabilistic analysis of random nonlinear oscillators subject to small perturbations via probability density functions: Theory and computing. European Physical Journal Plus. 136(7):1-23. https://doi.org/10.1140/epjp/s13360-021-01672-wS1231367W.L. Oberkampf, S.M. De Land, B.M. Rutherford, K.V. Diegert, K.F. Alvin, Error and uncertainty in modeling and simulation. Reliab. Eng. Syst. Saf. 75, 333–357 (2002)T. Soong, Random Differential Equations in Science and Engineering, vol. 103 (Academic Press, New York, 1973)Kloeden, P., Platen, E.: Numerical Solution of Stochastic Differential Equations, Ser. Stochastic Modelling and Applied Probability, vol. 23. Springer, Berlin Heidelberg (1992)J.L. Bogdanoff, J.E. Goldberg, M. Bernard, Response of a simple structure to a random earthquake-type disturbance. Bull. Seismol. Soc. Am. 51, 293–310 (1961)L. Su, G. Ahmadi, Earthquake response of linear continuous structures by the method of evolutionary spectra. Eng. Struct. 10, 47–56 (1988)X. Jin, Y. Tian, Y. Wang, Z. Huang, Explicit expression of stationary response probability density for nonlinear stochastic systems. Acta Mech. 232, 2101–2114 (2021)D. Lobo, T. Ritto, D. Castello, E. Cataldo, Dynamics of a Duffing oscillator with the stiffness modeled as a stochastic process. Int. J. Non-Linear Mech. 116, 273–280 (2019)Y. Lin, G. Cai, Probabilistic Structural Dynamics: Advanced Theory and Applications (McGraw-Hill, Cambridge, 1995)C. To, Nonlinear Random Vibration: Analytical Techniques and Applications (Swets & Zeitlinger, New York, 2000)M. Kaminski, The Stochastic Perturbation Method for Computational Mechanics (Wiley, New York, 2013)J.J. Stoker, Nonlinear Vibrations (Wiley (Interscience), New York, 1950)N. McLachlan, Laplace Transforms and Their Applications to Differential Equations, vol. 103 (Dover Publ. INc., New York, 2014)R.F. Steidel, An Introduction to Mechanical Vibrations (Wiley, New York, 1989)G. Casella, R. Berger, Statistical Inference (Cengage Learning, New Delhi, 2007)H.V. Storch, F.W. Zwiers, Statistical Analysis in Climate Research (Cambridge University Press, Cambridge, 2001)J.V. Michalowicz, J.M. Nichols, F. Bucholtz, Handbook of Differential Entropy (CRC Press, Boca Raton, 2018)H. Banks, H. Shuhua, W. Clayton Thompson, Modelling and Inverse Problems in the Presence of Uncertainty (Ser. Monographs and Research Notes in Mathematics. CRC Press, Boca Raton, 2001)Garg, V.K., Wang, Y.-C.: 1 - signal types, properties, and processes. In: Chen, W.-K. (ed.) The Electrical Engineering Handboo

Full solution of random autonomous first-order linear systems of difference equations. Application to construct random phase portrait for planar systems

[EN] This paper deals with the explicit determination of the first probability density function of the solution stochastic process to random autonomous first-order linear systems of difference equations under very general hypotheses. This finding is applied to extend the classical stability classification of the zero-equilibrium point based on phase portrait to the random scenario. An example illustrates the potentiality of the theoretical results established and their connection with their deterministic counterpart.This work has been partially supported by the Ministerio de Economia y Competitividad grant MTM2013-41765-P. Ana Navarro Quiles acknowledges the doctorate scholarship granted by Programa de Ayudas de Investigation y Desarrollo (PAID), Universitat Politecnica de Valencia.Cortés, J.; Navarro-Quiles, A.; Romero, J.; Roselló, M. (2017). Full solution of random autonomous first-order linear systems of difference equations. Application to construct random phase portrait for planar systems. Applied Mathematics Letters. 68:150-156. https://doi.org/10.1016/j.aml.2016.12.0151501566

Introducing randomness in the analysis of chemical reactions: An analysis based on random differential equations and probability density function

This is the peer reviewed version of the following article: Cortés, J-C, Navarro-Quiles, A, Romero, J-V, Roselló, M-D. Introducing randomness in the analysis of chemical reactions: An analysis based on random differential equations and probability density functions. Comp and Math Methods. 2021; 3:e1141, which has been published in final form at https://doi.org/10.1002/cmm4.1141. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] In this work we consider a particular randomized kinetic model for reaction-deactivation of hydrogen peroxide decomposition. We apply the Random Variable Transformation technique to obtain the first probability density function of the solution stochastic process under general conditions. From the rst probability density function, we can obtain fundamental statistical information, such as the mean and the variance of the solution, at every instant time. The transformation considered in the application of the Random Variable Transformation technique is not unique. Then, the first probability density function can take different expressions, although essentially equivalent in terms of computing probabilistic information. To motivate this fact, we consider in our analysis two different mappings. Several numerical examples show the capability of our approach and of the obtained results as well. We show, through simulations, that the choice of the transformation, that permits computing the first probability density function, is a crucial issue regarding the computational time.This work has been supported by the Spanish Ministerio de Economía, Industria y Competitividad (MINECO), the Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER UE) grant MTM2017-89664-P. Computations have been carried thanks to the collaboration of Raúl San Julián Garcés and Elena López Navarro granted by European Union through the Operational Program of the European Regional Development Fund (ERDF)/European Social Fund (ESF) of the Valencian Community 2014-2020, grants GJIDI/2018/A/009 and GJIDI/2018/A/010, respectively.Cortés, J.; Navarro-Quiles, A.; Romero, J.; Roselló, M. (2021). Introducing randomness in the analysis of chemical reactions: An analysis based on random differential equations and probability density function. Computational and Mathematical Methods. 3(6):1-10. https://doi.org/10.1002/cmm4.1141S1103