Diseño de un Instrumento para Evaluar el Valor Social Subjetivo de la Educación en Estudiantes, Docentes y Familias: Resultados de un Ensayo Piloto

Encontramos multitud de estudios sobre el diseño y validación de instrumentos de evaluación sobre variables socio-afectivas complejas. En estos casos ha sido evidente que un desarrollo sistemático de estandarización ha mejorado las propiedades métricas y su adecuación. Por ello planteamos algunos resultados previos sobre un estudio piloto para la construcción de un instrumento que evalúe el Valor Social Subjetivo de la Educación en tres audiencias (estudiantes, profesorado y familias). En este caso se presentan las propiedades métricas encontradas y las diferencias entre grupos con 131 estudiantes, 28 docentes y 36 familiares. En general los datos son adecuados en las tres escalas implementadas, sin embargo se encuentran nuevas líneas de indagación. Como conclusión se reflexiona sobre la necesidad de asegurar la fiabilidad y la validez de la escala para poder mejorar la investigación

A note on supercyclic operators in locally convex spaces

We treat some questions related to supercyclicity of continuous linear operators when acting in locally convex spaces. We extend results of Ansari and Bourdon and consider doubly power bounded operators in this general setting. Some examples are given

Dissipative operators and additive perturbations in locally convex spaces

"This is the peer reviewed version of the following article: Albanese, Angela A., and David Jornet. 2015. Dissipative Operators and Additive Perturbations in Locally Convex Spaces. Mathematische Nachrichten 289 (8 9). Wiley: 920 49. doi:10.1002/mana.201500150, which has been published in final form at https://doi.org/10.1002/mana.201500150. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] Let (A, D(A)) be a densely defined operator on a Banach space X. Characterizations of when (A, D(A)) generates a C-0-semigroup on X are known. The famous result of Lumer and Phillips states that it is so if and only if (A, D(A)) is dissipative and rg(lambda I - A) subset of X is dense in X for some lambda > 0. There exists also a rich amount of Banach space results concerning perturbations of dissipative operators. In a recent paper Tyran-Kaminska provides perturbation criteria of dissipative operators in terms of ergodic properties. These results, and others, are shown to remain valid in the setting of general non-normable locally convex spaces. Applications of the results to concrete examples of operators on function spaces are also presented. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimThe research of the second author was partially supported by MINECO of Spain, Project MTM2013-43540-P, by Programa de Apoyo a la Investigacion y Desarrollo de la UPV, PAID-06-12 and by Generalitat Valenciana ACOMP/2015/186.Albanese, AA.; Jornet Casanova, D. (2016). Dissipative operators and additive perturbations in locally convex spaces. Mathematische Nachrichten. 289(8-9):920-949. https://doi.org/10.1002/mana.201500150S9209492898-9Albanese, A. A., Bonet, J., & Ricker, W. J. (2010). C0-semigroups and mean ergodic operators in a class of Fréchet spaces. Journal of Mathematical Analysis and Applications, 365(1), 142-157. doi:10.1016/j.jmaa.2009.10.014Albanese, A. A., Bonet, J., & Ricker, W. J. (2011). Mean ergodic semigroups of operators. Revista de la Real Academia de Ciencias Exactas, Fisicas y Naturales. Serie A. Matematicas, 106(2), 299-319. doi:10.1007/s13398-011-0054-2Albanese, A. A., Bonet, J., & Ricker, W. J. (2013). Montel resolvents and uniformly mean ergodic semigroups of linear operators. Quaestiones Mathematicae, 36(2), 253-290. doi:10.2989/16073606.2013.779978Albanese, A. A., Bonet, J., & Ricker, W. J. (2013). Convergence of arithmetic means of operators in Fréchet spaces. Journal of Mathematical Analysis and Applications, 401(1), 160-173. doi:10.1016/j.jmaa.2012.11.060Albanese, A. A., Bonet, J., & Ricker, W. J. (2014). Uniform mean ergodicity of $C_0$-semigroups\newline in a class of Fréchet spaces. Functiones et Approximatio Commentarii Mathematici, 50(2), 307-349. doi:10.7169/facm/2014.50.2.8Domański, P., & Langenbruch, M. (2011). On the abstract Cauchy problem for operators in locally convex spaces. Revista de la Real Academia de Ciencias Exactas, Fisicas y Naturales. Serie A. Matematicas, 106(2), 247-273. doi:10.1007/s13398-011-0052-4Frerick, L., Jordá, E., Kalmes, T., & Wengenroth, J. (2014). Strongly continuous semigroups on some Fréchet spaces. Journal of Mathematical Analysis and Applications, 412(1), 121-124. doi:10.1016/j.jmaa.2013.10.053B. Jacob S.-A. Wegner Asymptotics of solution equations beyond Banach spaces Semigroup ForumJacob, B., Wegner, S.-A., & Wintermayr, J. (2015). Desch-Schappacher perturbation of one-parameter semigroups on locally convex spaces. Mathematische Nachrichten, 288(8-9), 925-934. doi:10.1002/mana.201400116Köthe, G. (1983). Topological Vector Spaces I. Grundlehren der mathematischen Wissenschaften. doi:10.1007/978-3-642-64988-2Köthe, G. (1979). Topological Vector Spaces II. Grundlehren der mathematischen Wissenschaften. doi:10.1007/978-1-4684-9409-9KOMATSU, H. (1964). Semi-groups of operators in locally convex spaces. Journal of the Mathematical Society of Japan, 16(3), 230-262. doi:10.2969/jmsj/01630230Kōmura, T. (1968). Semigroups of operators in locally convex spaces. Journal of Functional Analysis, 2(3), 258-296. doi:10.1016/0022-1236(68)90008-6Lumer, G., & Phillips, R. S. (1961). Dissipative operators in a Banach space. Pacific Journal of Mathematics, 11(2), 679-698. doi:10.2140/pjm.1961.11.679Miyadera, I. (1959). Semi-groups of operators in Fréchet space amd applications to partial differential equations. Tohoku Mathematical Journal, 11(2), 162-183. doi:10.2748/tmj/1178244580Moscatelli, V. B. (1980). Fréchet Spaces without continuous Norms and without Bases. Bulletin of the London Mathematical Society, 12(1), 63-66. doi:10.1112/blms/12.1.63Tyran-Kamińska, M. (2009). Ergodic theorems and perturbations of contraction semigroups. Studia Mathematica, 195(2), 147-155. doi:10.4064/sm195-2-4S.-A. Wegner The growth bound for strongly continuous semigroups on Fréchet spaces Proc. Edinb. Math. Soc. (2) (to appear) 10.1017/S001309151500031

A Note on Supercyclic Operators in Locally Convex Spaces

[EN] We treat some questions related to supercyclicity of continuous linear operators when acting in locally convex spaces. We extend results of Ansari and Bourdon and consider doubly power bounded operators in this general setting. Some examples are given.We are indebted to Prof. Jose Bonet for his helpful suggestions on the topic of this paper. The authors were partially supported by the project MTM2016-76647-P.Albanese, AA.; Jornet Casanova, D. (2019). A Note on Supercyclic Operators in Locally Convex Spaces. Mediterranean Journal of Mathematics. 16(5):1-10. https://doi.org/10.1007/s00009-019-1386-yS11016

A Definition of the Magnetic Transition Temperature Using Valence Bond Theory

Macroscopic magnetic properties are analyzed using Valence Bond theory. Commonly the critical temperature TC for magnetic systems is associated with a maximum in the energy-based heat capacity Cp(T). Here a more broadly applicable definition of the magnetic transition temperature TC is described using the spin moment expectation value (i.e., applying the spin exchange density operator) instead of energy. Namely, the magnetic capacity Cs(T) reflects variation in the spin multiplicity as a function of temperature, which is shown to be related to ∂[χT(T)]/∂T. Magnetic capacity Cs(T) depends on long-range spin interactions that are not relevant in the energy-based heat capacity Cp(T). Differences between Cs(T) and Cp(T) are shown to be due to spin order/disorder within the crystal that can be monitored via a Valence Bond analysis of the corresponding magnetic wave function. Indeed the concept of the Boltzmann spin-alignment order is used to provide information about the spin correlation between magnetic units. As a final illustration, the critical temperature is derived from the magnetic capacity for several molecular magnets presenting different magnetic topologies that have been experimentally studied. A systematic shift between the transition temperatures associated with Cs(T) and Cp(T) is observed. It is demonstrated that this shift can be attributed to the loss of long-range spin correlation. This suggests that the magnetic capacity Cs(T) can be used as a predictive tool for the magnetic topology and thus for the synthetic chemists

Electronic Descriptors for Supervised Spectroscopic Predictions

Spectroscopic properties of molecules holds great importance for the description of the molecular response under the effect of an UV/Vis electromagnetic radiation. Computationally expensive ab initio (e.g. MultiConfigurational SCF, Coupled Cluster) or TDDFT methods are commonly used by the quantum chemistry community to compute these properties. In this work, we propose a (supervised) Machine Learning approach to model the absorption spectra of organic molecules. Several supervised ML methods have been tested such as Kernel Ridge Regression (KRR), Multiperceptron Neural Networs (MLP) and Convolutional Neural Networks. The use of only geometrical descriptors (e.g. Coulomb Matrix) proved to be insufficient for an accurate training. Inspired on the TDDFT theory, we propose to use a set of electronic descriptors obtained from low-cost DFT methods: orbital energy differences, transition dipole moment between occupied and unoccupied Kohn-Sham orbitals and charge-transfer character of mono-excitations. We demonstrate that with this electronic descriptors and the use of Neural Networks we can predict not only a density of excited states, but also getting very good estimation of the absorption spectrum and charge-transfer character of the electronic excited states, reaching results close to the chemical accuracy (~2 kcal/mol or ~0.1eV)

A basic electro-topological descriptor for the prediction of organic molecule geometries by simple machine learning

This paper proposes a machine learning (ML) method to predict stable molecular geometries from their chemical composition. The method is useful for generating molecular conformations which may serve as initial geometries for saving time during expensive structure optimizations by quantum mechanical calculations of large molecules. Conformations are found by predicting the local arrangement around each atom in the molecule after trained from a database of previously optimized small molecules. It works by dividing each molecule in the database into minimal building blocks of different type. The algorithm is then trained to predict bond lengths and angles for each type of building block using an electro-topological fingerprint as descriptor. A conformation is then generated by joining the predicted blocks. Our model is able to give promising results for optimized molecular geometries from the basic knowledge of the chemical formula and connectivity. The method trends to reproduce interatomic distances within test blocks with RMSD under 0.05

Nanoantennas Design for THz Communication: Material Selection and Performance Enhancement

In the development of terahertz (THz) communication systems, the nanoantenna is the most significant component. Especially, the focus is to design highly directive antennas, because it enhances the performance of the overall system by compensating the large path loss at THz and thus improves the signal-to-noise ratio. This paper presents suitable material for nanoantenna design and the advancement in their performance for THz communications. Copper, Graphene, and carbon nanotube materials are used as promising candidates for nanoantenna design. The performance of nanoantennas is carried out by analyzing the properties and behavior of the material at THz. Results show that the Graphene nanoantenna provides better performance in terms of miniaturization, directivity, and radiation efficiency. Further, the performance enhancement of the nanoantenna at THz is studied by dynamically adjusting the surface conductivity via the chemical potential of Graphene using the electric field effect. The performance of the nanoantenna is enhanced in terms of high miniaturization, high directivity, low reflection, frequency reconfiguration, and stable impedance. The THz nanoantennas using Graphene have the potential to be used for THz communication systems. In view of the smart THz wireless environment; this paper finally presents a THz Hypersurface using Graphene meta-atoms. The user-side Graphene nanoantennas and environment-side Graphene Hypersurface can build a promising smart THz wireless environment