Neural approach to estimate the stress intensity factor of semi‐elliptical cracks in rotating cracked shafts in bending

In the last decades, neural network approach has often been used to study various and complex engineering problems, such as optimization or prediction. In this paper, a methodology founded on artificial neural networks (ANNs) was used to calculate the stress intensity factor (SIF) in different points of the front of a semi‐elliptical crack present in a rotating shaft, taking into account the shape and depth of the crack, the angle of rotation, and the location of the point in the front. In the event of rotating machines, such as shafts, it is crucial to know the SIF along the crack front because this parameter, according to the Paris Law, is related to the performance of the crack during its propagation. Previously, it was necessary to achieve the data for the ANN training, for this a quasi‐static numerical model was made, which simulates a rotating cracked shaft with a semi‐elliptical crack. The numerical solutions cover a wide range of crack depths and shapes, and rotation angles. The values of the SIF estimated by the ANNs were contrasted with other solutions available in the literature finding a good agreement between them. The proposed neural network methodology is an alternative that offers a very good option for the SIF estimation, because it is efficient and easy to use, does not require high computational costs, and can be used to analyse the propagation of cracks contained in rotating shafts by means of the Paris Law taking into account the nonlinear behaviour of the shaft.The authors would like to thank the Spanish Ministerio de Economía y Competitividad for the support for this work through the projects DPI2009-13264 and DPI2013-45406-

A closed expression for the stress intensity factor of concave fatigue cracks in rotating shafts

A new analytical model is developed that allows us to obtain the Stress Intensity Factor (SIF) in a point on a concave shaped crack contained in a rotating shaft as a function of the characteristics of the crack (depth and aspect), the point position on the crack front, and the rotation angle. The model can be used for all kinds of linear elastic materials. The Finite Element Method (FEM) has been used to make a tridimensional quasi-static model of a shaft that contains a concave shaped crack in its central section, subjected to rotary bending. Different rotation angles are taken into account in order to simulate the rotation of the shaft. The SIF is determined in every position of the front of the concave crack, for each crack geometry and for each rotation angle. Then an analytical model is developed using all the results of SIF obtained with the numerical model, and is verified comparing its results with solutions found in the literature. The proposed model may be very useful to study the dynamic behavior of shafts with concave shaped cracks, and can be employed to analyze the propagation of these types of cracks.The authors would like to thank the Spanish Ministerio de Economía y Competitividad for the support for this work through the projects DPI2009-13264 and DPI2013-45406-

Elliptical Crack Identification in a Nonrotating Shaft

It is known that fatigue cracks are one of the most important problems of the mechanical components, since their propagation can cause severe loss, both personal and economic. So, it is essential to know deeply the behavior of the cracked element to have tools that allow predicting the breakage before it happens. The shafts are elements that are specially affected by the described problem, because they are subjected to alternative compression and tension stresses., is work presents, firstly, an analytical expression that allows determining the first four natural frequencies of bending vibration of a nonrotating cracked shaft, assumed as an Euler-Bernoulli beam, with circular cross section under pinned-pinned conditions, taking into account the elliptical shape of the crack. Second, once the direct problem is known, the inverse problem is approached. Genetic Algorithm technique has been used to estimate the crack parameters assuming known the natural frequencies of the cracked shaft.The authors would like to thank the Spanish Ministerio de Economía y Competitividad for the support for this work through the project DPI2013-45406-P

Modelling Biological Systems: A New Algorithm for the Inference of Boolean Networks

[EN] Biological systems are commonly constituted by a high number of interacting agents. This great dimensionality hinders biological modelling due to the high computational cost. Therefore, new modelling methods are needed to reduce computation time while preserving the properties of the depicted systems. At this point, Boolean Networks have been revealed as a modelling tool with high expressiveness and reduced computing times. The aim of this work has been to introduce an automatic and coherent procedure to model systems through Boolean Networks. A synergy that harnesses the strengths of both approaches is obtained by combining an existing approach to managing information from biological pathways with the so-called Nested Canalising Boolean Functions (NCBF). In order to show the power of the developed method, two examples of an application with systems studied in the bibliography are provided: The epithelial-mesenchymal transition and the lac operon. Due to the fact that this method relies on directed graphs as a primary representation of the systems, its applications exceed life sciences into areas such as traffic management or machine learning, in which these graphs are the main expression of the systems handled.This paper has been supported by the Generalitat Valenciana grant AICO/2020/114Rubio-Chavarría, M.; Santamaria Navarro, C.; García Mora, MB.; Rubio Navarro, G. (2021). Modelling Biological Systems: A New Algorithm for the Inference of Boolean Networks. Mathematics. 9(4):1-22. https://doi.org/10.3390/math9040373S1229

A Phase-Type Distribution for the Sum of Two Concatenated Markov Processes Application to the Analysis Survival in Bladder Cancer

[EN] Stochastic processes are useful and important for modeling the evolution of processes that take different states over time, a situation frequently found in fields such as medical research and engineering. In a previous paper and within this framework, we developed the sum of two independent phase-type (PH)-distributed variables, each of them being associated with a Markovian process of one absorbing state. In that analysis, we computed the distribution function, and its associated survival function, of the sum of both variables, also PH-distributed. In this work, in one more step, we have developed a first approximation of that distribution function in order to avoid the calculation of an inverse matrix for the possibility of a bad conditioning of the matrix, involved in the expression of the distribution function in the previous paper. Next, in a second step, we improve this result, giving a second, more accurate approximation. Two numerical applications, one with simulated data and the other one with bladder cancer data, are used to illustrate the two proposed approaches to the distribution function. We compare and argue the accuracy and precision of each one of them by means of their error bound and the application to real data of bladder cancer.This paper has been supported by the Generalitat Valenciana grant AICO/2020/114.García Mora, MB.; Santamaria Navarro, C.; Rubio Navarro, G. (2020). A Phase-Type Distribution for the Sum of Two Concatenated Markov Processes Application to the Analysis Survival in Bladder Cancer. Mathematics. 8(12):1-15. https://doi.org/10.3390/math8122099S115812Rodríguez, J., Lillo, R. E., & Ramírez-Cobo, P. (2015). Failure modeling of an electrical N-component framework by the non-stationary Markovian arrival process. Reliability Engineering & System Safety, 134, 126-133. doi:10.1016/j.ress.2014.10.020García‐Mora, B., Santamaría, C., & Rubio, G. (2020). Markovian modeling for dependent interrecurrence times in bladder cancer. Mathematical Methods in the Applied Sciences, 43(14), 8302-8310. doi:10.1002/mma.6593Montoro-Cazorla, D., & Pérez-Ocón, R. (2014). Matrix stochastic analysis of the maintainability of a machine under shocks. Reliability Engineering & System Safety, 121, 11-17. doi:10.1016/j.ress.2013.07.002Fackrell, M. (2008). Modelling healthcare systems with phase-type distributions. Health Care Management Science, 12(1), 11-26. doi:10.1007/s10729-008-9070-yGarg, L., McClean, S., Meenan, B. J., & Millard, P. (2011). Phase-Type Survival Trees and Mixed Distribution Survival Trees for Clustering Patients’ Hospital Length of Stay. Informatica, 22(1), 57-72. doi:10.15388/informatica.2011.314Marshall, A. H., & McClean, S. I. (2003). Conditional phase-type distributions for modelling patient length of stay in hospital. International Transactions in Operational Research, 10(6), 565-576. doi:10.1111/1475-3995.00428Marshall, A. H., & McClean, S. I. (2004). Using Coxian Phase-Type Distributions to Identify Patient Characteristics for Duration of Stay in Hospital. Health Care Management Science, 7(4), 285-289. doi:10.1007/s10729-004-7537-zFackrell, M. (2012). A semi-infinite programming approach to identifying matrix-exponential distributions. International Journal of Systems Science, 43(9), 1623-1631. doi:10.1080/00207721.2010.549582García-Mora, B., Santamaría, C., Rubio, G., & Pontones, J. L. (2013). Computing survival functions of the sum of two independent Markov processes: an application to bladder carcinoma treatment. International Journal of Computer Mathematics, 91(2), 209-220. doi:10.1080/00207160.2013.765560Kenney, C., & Laub, A. J. (1989). Condition Estimates for Matrix Functions. SIAM Journal on Matrix Analysis and Applications, 10(2), 191-209. doi:10.1137/0610014Jackson, C. H. (2011). Multi-State Models for Panel Data: ThemsmPackage forR. Journal of Statistical Software, 38(8). doi:10.18637/jss.v038.i08Mullin, L., & Raynolds, J. (2014). Scalable, Portable, Verifiable Kronecker Products on Multi-scale Computers. Studies in Computational Intelligence, 111-129. doi:10.1007/978-3-319-04280-0_1

Histone Mutants Separate R Loop Formation from Genome Instability Induction

R loops have positive physiological roles, but they can also be deleterious by causing genome instability, and the mechanisms for this are unknown. Here we identified yeast histone H3 and H4 mutations that facilitate R loops but do not cause instability. R loops containing single-stranded DNA (ssDNA), versus RNA-DNA hybrids alone, were demonstrated using ssDNA-specific human AID and bisulfite. Notably, they are similar size regardless of whether or not they induce genome instability. Contrary to mutants causing R loop-mediated instability, these histone mutants do not accumulate H3 serine-10 phosphate (H3S10-P). We propose a two-step mechanism in which, first, an altered chromatin facilitates R loops, and second, chromatin is modified, including H3S10-P, as a requisite for compromising genome integrity. Consistently, these histone mutations suppress the high H3S10 phosphorylation and genomic instability of hpr1 and sen1 mutants. Therefore, contrary to what was previously believed, R loops do not cause genome instability by themselves.European Research Council ERC2014 AdG669898Ministerio de Economía y Competitividad BFU2013-42918-P, BFU2016-75058-

Minimal slant submanifolds of the smallest dimension in S-manifolds

We study slant submanifolds of S-manifolds with the smallest dimension, specially minimal submanifolds and establish some relations between them and anti-invariant submanifolds in S-manifolds, similar to those ones proved by B.-Y. Chen for slant surfaces and totally real surfaces in Kaehler manifolds.Plan Andaluz de Investigación (Junta de Andalucía

The DNA damage response acts as a safeguardagainst harmful DNA–RNA hybrids ofdifferent origins

Despite playing physiological roles in specific situations, DNA–RNA hybrids threat genome integrity. To investigate how cells do counteract spontaneous DNA–RNA hybrids, here we screen an siRNA library covering 240 human DNA damage response (DDR) genes and select siRNAs causing DNA–RNA hybrid accumulation and a significant increase in hybrid‐dependent DNA breakage. We identify post‐replicative repair and DNA damage checkpoint factors, including those of the ATM/CHK2 and ATR/CHK1 pathways. Thus, spontaneous DNA–RNA hybrids are likely a major source of replication stress, but they can also accumulate and menace genome integrity as a consequence of unrepaired DSBs and post‐replicative ssDNA gaps in normal cells. We show that DNA–RNA hybrid accumulation correlates with increased DNA damage and chromatin compaction marks. Our results suggest that different mechanisms can lead to DNA–RNA hybrids with distinct consequences for replication and DNA dynamics at each cell cycle stage and support the conclusion that DNA–RNA hybrids are a common source of spontaneous DNA damage that remains unsolved under a deficient DDR.European Research Council (ERC2014AdG669898TARLOOP)Worldwide Cancer Research (WCR15-00098

Utilización de la red social Instagram para fomentar la práctica continuada del alumnado en la nomenclatura y formulación de compuestos orgánicos

Introducción El aprendizaje de la formulación y nomenclatura de compuestos orgánicos constituye una de las competencias más importantes en la asignatura de Química Orgánica I. Para ello, la resolución de ejercicios constituye una herramienta fundamental que actualmente se integra en el aula. Sin embargo, el grado de implicación del alumnado en la realización de estos ejercicios es, en muchas ocasiones, escaso, lo que lleva a que exista un alto porcentaje de alumnos y alumnas que tienen dificultades para aprobar satisfactoriamente esta parte de la materia. Objetivo La implementación de un Proyecto de Innovación Docente (PID) que propone la creación de un recurso didáctico para mejorar la adquisición de las competencias relativas a formulación orgánica y fomentar la implicación del alumnado de forma interactiva mediante el empleo de la red social Instagram. Metodología A partir de un banco de preguntas previamente elaborado por los integrantes del equipo docente, se prepararon una serie de cuestionarios que fueron compartidos a modo de stories en el perfil de una cuenta de Instagram creada a tal fin. Estos cuestionarios proporcionaron al alumnado una retroalimentación instantánea al completar el ejercicio, mostrando la respuesta correcta así como una explicación acorde con las reglas de la IUPAC. Resultados El impacto de la intervención fue evaluado tanto cualitativamente, mediante encuestas de percepción, como cuantitativamente, mediante el análisis de los datos derivados de la plataforma Instagram, así como de las calificaciones obtenidas en los exámenes de formulación parcial, final y extraordinario, mostrando una alta aceptación por parte del alumnado y una mejora de los resultados académicos. Conclusiones Instagram es una herramienta útil para la práctica de la formulación en la asignatura de Química Orgánica I que mejora la eficacia del proceso de transferencia de información entre profesor y alumno/a. La implantación de este recurso proporciona una herramienta atractiva e innovadora que, al mismo tiempo, refuerza los conocimientos adquiridos en clase en un contexto más cercano y mejora los resultados académicos

Revisión bibliográfica sobre el síndrome de burnout y sus efectos en la enfermería de España

Introducción: El concepto "burnout", equivalente a desgaste profesional, constituye un problema de gran relevancia. Su prevalencia se estima entre un 10-50% de los trabajadores y si nos centramos sólo en enfermería, seis de cada diez profesionales padecen el síndrome de burnout. Objetivo: realizar un análisis sobre como afecta el síndrome de burnout a la enfermería en España y de que forma se podría enfocar su prevención. Metodología: se realizó una búsqueda bibliográfica durante los meses de enero y febrero de 2013 en las bases de datos: Biblioteca Cochrame Plus, Cuiden, CUIDATGE, ENFISPO y el buscador Encuentr@. Tras aplicar los criterios de inclusión nos quedamos con 12 estudios científicos. Desarrollo: los estudios reflejan mayores niveles de despersonalización y cansancio emocional que de falta de realización personal, pero la diferencia es mínima. Existen mayores niveles de burnout en mujeres que en hombres, en solteros que en casados y en profesionales sin hijos que con hijos. También hay mayores niveles de burnout en los enfermeros que en otras profesiones sanitarias, en los profesionales que llevan más de 10 años trabajando, en los que tienen plaza fija y en los que trabajan en turnos rotatorios frente en los que lo hacen en otro turno. Conclusiones: el perfil de riesgo de padecer burnout en enfermería sería el de una mujer soltera, sin hijos, con más de 10 años de antigüedad profesional, con plaza fija y turno rotatorio. En consecuencia la prevención debería estar enfocada especialmente en este tipo de profesionales