Spin torque driven dynamics of a coupled two layer structure: interplay between conservative and dissipative coupling

In this manuscript the general concepts of spin wave theory are adapted to the dynamics of a self-polarized system based on two layers coupled via interlayer exchange (conservative coupling) and mutual spin torque (dissipative coupling). An analytical description of the non-linear dynamics is proposed and validated through numerical simulations. In contrast to the single layer model, the phase equation of the coupled system has a contribution coming from the dissipative part of the LLGS equation. It is shown that this is a major contribution to the frequency mandatory to describe well the most basic features of the dynamics of coupled systems. Using the proposed model a specific feature of coupled dynamics is addressed: the redshift to blueshift transition observed in the frequency current dependence of this kind of exchange coupled systems upon increasing the applied field. It is found that the blueshift regime can only occur in a region of field where the two linear eigenmodes contribute equally to the steady state mode (i.e. high mode hybridization). Finally, a general perturbed Hamiltonian equation for the coupled system is proposed.Comment: 16 pages, 7 figue

Identifying wave packet fractional revivals by means of information entropy

Wave packet fractional revivals is a relevant feature in the long time scale evolution of a wide range of physical systems, including atoms, molecules and nonlinear systems. We show that the sum of information entropies in both position and momentum conjugate spaces is an indicator of fractional revivals by analyzing three different model systems: $(i)$ the infinite square well, $(ii)$ a particle bouncing vertically against a wall in a gravitational field, and $(iii)$ the vibrational dynamics of hydrogen iodide molecules. This description in terms of information entropies complements the usual one in terms of the autocorrelation function

La antropología de Cornelio Fabro

Cornelio Fabro’s rich anthropological reflections are not as well known as his writings and essays on Saint Thomas Aquinas, Søren Kierkegaard and atheism. His research on perception and freedom aims to obtain a more comprehensive understanding of the existential unity of the human person. In this article, we develop the key concepts of Fabro’s thought on freedom, which are based primarily upon his university lectures and other unpublished manuscripts

Optimisation of thin-walled hybrid vertical struts for crashworthy aircraft designs

[Abstract:] This research concerns the crashworthiness enhancement of a model of a Boeing 737-200 fuselage section. Using a validated numerical specimen, four thin-walled crushable hybrid energy absorbers are added to the aircraft to work as vertical struts. The absorbers are composed of a hollow aluminium tube, a star-shaped glass fibre–reinforced polymer inner matrix and foam extrusions. The absorbers—with variable tube edge and thickness, composite thickness and core height—are single- and multi-objectively optimised. Surrogate models and genetic algorithms are used for the minimisation of acceleration loads, injury levels and the strut’s weight. Results yield a more efficient frames’ collapse evolution with plastic dissipation increased by over 50%. Consequently, acceleration peaks are up to 50% lower at the two measured locations while maintaining low mass values. Injury levels were also reduced from severe to moderate according to an Eiband diagram.Ministerio de Economía y Competitividad; DPI2016-76934-

Crashworthiness study on hybrid energy absorbers as vertical struts in civil aircraft fuselage designs

[Abstract:] This research concerns the crashworthiness study and enhancement of commercial aircraft fuselage structures by incorporating crushable hybrid energy absorbers to work as vertical struts. To assess their contribution on a representative aircraft structure, a numerical simulation of a Boeing 737-200 drop test is developed and validated with experimental data available in the literature. The fuselage section is then simulated both with and without the fuel tank, showing more harmful effects for the latter scenario. The numerical model accurately captures the experiment’s collapse process with low artificial energy ratios. Later, four vertical hybrid energy absorbers designed for programmed and progressive collapse, are added in the cargo compartment, connecting the underfloor beams and the frames. Different designs and positions are studied, combining aluminum tubes with square and circular cross-sections, filled with a core made from a GFRP skeleton and foam extrusions. Acceleration graphs show a reduction in passenger injury levels from severe to moderate according to an Eiband diagram when energy absorbers are fitted. Energy trends from the hybrid absorbers are also monitored, with dissipation of up to 10 kJ of the fuselage’s kinetic energy through plastic deformation and collapse. Results also show a significant improvement on the global crashworthiness of the fuselage, leading to an increase in plastic dissipation by the frames from 76 kJ to 122 kJ and a reduction on the accelerations up to 50% when the energy-absorbing structures are added.Ministerio de Economía, Industria, y Competitividad. MINECO; DPI2016-76934-RMinisterio de Economía, Industria, y Competitividad; DPI2016-76934-

La razón responsable y la universidad: el lugar de la teología

La universidad se encuentra hoy en día ante el desafío de ampliar los horizontes de la razón, superando los reduccionismos y relativismos presentes en nuestra época. Dicho desafío requiere elaborar un conocimiento sapiencial en tres niveles. Para empezar en la propia disciplina, en segundo lugar en un plano filosófico, en tercer lugar en la teología. Sabiduría en las disciplinas científicas significa no limitarse, en el propio quehacer académico, a la asunción de una metodología y de los conceptos con los que se piensan e interpretan los resultados, para trabajar desde esos presupuestos. La actitud sapiencial consiste precisamente en reconsiderar los presupuestos sobre los que se edifica la investigación, examinar el alcance de los paradigmas hermenéuticos con los que se trabaja y desarrollar intelecciones integrales del ámbito de estudio correspondiente. El segundo nivel de elaboración sapiencial es de naturaleza filosófica. En la filosofía se obtiene una visión integral del hombre y de la realidad que no va en detrimento de las ciencias. Todo lo contrario, responde a una exigencia de la misma razón que permite a las ciencias tener consistencia como ciencias. Recuperar la amplitud de la razón lleva consigo la elaboración de un pensamiento sapiencial en un tercer nivel, a saber, el de la sabiduría teológica. La fe aparece en el horizonte de la inteligencia en la medida en que el ser humano se percata, por una parte, de sus exigencias de saber, concretamente de comprensiones sapienciales, y, por otra, de enfrentarse con un misterio cuando considera con radicalidad las preguntas últimas con respecto a sí mismo y a la realidad

HE4 in endometriod and non- Endometrioid subtype of endometrial cancer does not mean the same

Objective: To study the association between the preoperative value of serum HE4 marker and poor histological prognostic factors depending on the subtype of endometrial cancer (EC): endometrioid and non-endometrioid tumors. Methods: Prospective and multicenter cohort study including patients with EC in Miguel Servet University Hospital of Zaragoza (Spain) and Hospital Clínico San Carlos of Madrid (Spain) from January 2017 to March 2020. Preoperative serum levels of HE4 were analyzed by clinical and pathological characteristics. Results: Overall, 190 patients were included. Of them, 158 were subtype I of EC and 32 were subtype II tumors. In endometrioid EC, a statistically significant association was found between the preoperative HE4 value and tumor size (p < 0.001), deep myometrial invasion (p = 0.001), lymphovascular space invasion (LVSI) (p = 0.002), cervical (p = 0.001), adnexal (p = 0.023), isthmus (p < 0.001) and parametrial involvement (p = 0.012), lymph node metastasis (p = 0.025) and FIGO stage (p < 0.001). On the contrary, no histological factors showed statistical association except LVSI (p = 0.025) in the non-endometrioid subtype. Conclusions: The preoperative value of HE4 is related differently with several established prognostic factors for EC according to the histological type of tumor. These results could be relevant in order to standardize a prognostic value of HE4 in EC

A Generalized Statistical Complexity Measure: Applications to Quantum Systems

A two-parameter family of complexity measures $\tilde{C}^{(\alpha,\beta)}$ based on the R\'enyi entropies is introduced and characterized by a detailed study of its mathematical properties. This family is the generalization of a continuous version of the LMC complexity, which is recovered for $\alpha=1$ and $\beta=2$. These complexity measures are obtained by multiplying two quantities bringing global information on the probability distribution defining the system. When one of the parameters, $\alpha$ or $\beta$, goes to infinity, one of the global factors becomes a local factor. For this special case, the complexity is calculated on different quantum systems: H-atom, harmonic oscillator and square well.Comment: 15 pages, 3 figure