Structural properties of minimal strong digraphs versus trees

Producción CientíficaIn this article, we focus on structural properties of minimal strong digraphs (MSDs). We carry out a comparative study of properties of MSDs versus (undirected) trees. For some of these properties, we give the matrix version, regarding nearly reducible matrices. We give bounds for the coefficients of the characteristic polynomial corresponding to the adjacency matrix of trees, and we conjecture bounds for MSDs. We also propose two different representations of an MSD in terms of trees (the union of a spanning tree and a directed forest; and a double directed tree whose vertices are given by the contraction of connected Hasse diagrams).Ministerio de Economía, Industria y Competitividad ( grant MTM2015-65764-C3-1-P

Factibilidad para el uso de plataformas virtuales en la docencia del nivel medio

In order to carry out this research, the use of educational technology in the high schools of Mazatenango, Suchitepéquez, was proposed as the object of study, which allows the opening to new modalities of assignment and delivery of tasks, virtual environments and new learning paradigms, as a way out of the current demotivating traditional teaching. Observing the influence exerted by the Internet in all social spheres of human beings through Information and Communication Technologies, it was considered interesting to incorporate the technology provided by the world of work, communication and informatics in the teaching practice. In the basic cycle of the secondary level of education in Mazatenango, Suchitepéquez has limited the use of electronic devices as support for teaching and as a tool for feedback and evidence of learning of collaborative work of students. Time management in the face-to-face classroom is not always sufficient to generate discussion, analysis and reflection on the contents. Virtual platforms are an answer to the dosage of time, the delivery of multimedia didactic resources and the centralized work in a personal network in the face of the uncertainty of the conjunctural situations that interrupt the face-to-face training process. The study classifies the elements and criteria that should be considered to implement these digital solutions in secondary schools of the official sector, for which it recommends the testing and installation of five open source platforms of simple configuration to create personal and efficient virtual learning environments. The suggested digital platforms have two modes of assembly and a distribution of general elements that allow adapting the training process to achieve digital skills and the use of electronic media. The study detected the bases that differentiate the modalities of education through the Internet, the necessary considerations to use virtuality and the optimal functioning of the suggested educational platforms. It is determined that the multiple technological solutions should be regulated through feasible elements of productivity, management, income and participation to create digital communities. It is recommended to favor synchronous learning as an accompaniment inside and outside the digital platforms

Random Generation of Arbitrary Waveforms for Emulating Three-Phase Systems

This paper describes an apparatus for generating a signal representative of steady-state and transient disturbances in three-phase waveforms of an ac electrical system as described in IEEE Std 1159-09. It can be configured as a synthesizer of randomly distorted signals for different applications: for testing the effects of disturbed grid on equipment and to generate patterns of electrical disturbances for the training of artificial neural networks, which are used for measuring power quality tasks. For the first purpose, voltage and current amplifiers are added in the output stage, which allows the generation of disturbed signals at grid level.Comisión Interministerial de Ciencia y Tecnología DPI2006-15467-C02-01Comisión Interministerial de Ciencia y Tecnología DPI2006-15467-C02-0

Problemas en el reconocimiento del límite Misisipiense/Pensilvaniense en el Norte de la Península Ibérica

XXI Jornadas de la Sociedad Española de Paleontología, Sevilla 4-8 Octubre 2005Se discute el origen de una nueva sub-especie del conodonto Declinognathodus noduliferus y su probable aparición más temprana que D. inaequalis en el norte de la Península Ibérica.Ministerio de Educación y Ciencia; BTE2003-01609Ministerio de Educación y Ciencia; BTE-0101

All-optical non-linear chiral ultrafast magnetization dynamics driven by circularly polarized magnetic fields

Ultrafast laser pulses provide unique tools to manipulate magnetization dynamics at femtosecond timescales, where the interaction of the electric field usually dominates over the magnetic field. Recent proposals using structured laser beams have demonstrated the possibility to produce regions where intense oscillating magnetic fields are isolated from the electric field. In these conditions, we show that technologically feasible Tesla-scale circularly polarized high-frequency magnetic fields induce purely precessional nonlinear magnetization dynamics. This fundamental result not only opens an avenue in the study of laser-induced ultrafast magnetization dynamics, but also sustains technological implications as a route to promote all-optical non-thermal magnetization dynamics both at shorter timescales—towards the subfemtosecond regime— and at THz frequencies

The Role of Mitochondria in Brain Aging and the Effects of Melatonin

Melatonin is an endogenous indoleamine present in different tissues, cellular compartments and organelles including mitochondria. When melatonin is administered orally, it is readily available to the brain where it counteracts different processes that occur during aging and age-related neurodegenerative disorders. These aging processes include oxidative stress and oxidative damage, chronic and acute inflammation, mitochondrial dysfunction and loss of neural regeneration. This review summarizes age related changes in the brain and the importance of oxidative/nitrosative stress and mitochondrial dysfunction in brain aging. The data and mechanisms of action of melatonin in relation to aging of the brain are reviewed as well

Animal Models of Coenzyme Q Deficiency: Mechanistic and Translational Learnings

Funding: This work was supported by grants from the MCIN/AEI/10.13039/501100011033, Spain, and the ERDF (RTI2018-093503-B-100); the Muscular Dystrophy Association (MDA-602322); and from the Junta de Andalucía (grant number P20_00134). P.G.-G. is ‘FPU fellow’ from the Ministerio de Universidades, Spain. A.H.-G. is supported by the “Plan Propio de Investigación” from the University of Granada. S.L.-H. is supported by the “garantía juvenil” program. E.B.-C. is supported by the Consejería de Salud, Junta de Andalucía, Spain.Coenzyme Q (CoQ) is a vital lipophilic molecule that is endogenously synthesized in the mitochondria of each cell. The CoQ biosynthetic pathway is complex and not completely characterized, and it involves at least thirteen catalytic and regulatory proteins. Once it is synthesized, CoQ exerts a wide variety of mitochondrial and extramitochondrial functions thank to its redox capacity and its lipophilicity. Thus, low levels of CoQ cause diseases with heterogeneous clinical symptoms, which are not always understood. The decreased levels of CoQ may be primary caused by defects in the CoQ biosynthetic pathway or secondarily associated with other diseases. In both cases, the pathomechanisms are related to the CoQ functions, although further experimental evidence is required to establish this association. The conventional treatment for CoQ deficiencies is the high doses of oral CoQ10 supplementation, but this therapy is not effective for some specific clinical presentations, especially in those involving the nervous system. To better understand the CoQ biosynthetic pathway, the biological functions linked to CoQ and the pathomechanisms of CoQ deficiencies, and to improve the therapeutic outcomes of this syndrome, a variety of animal models have been generated and characterized in the last decade. In this review, we show all the animal models available, remarking on the most important outcomes that each model has provided. Finally, we also comment some gaps and future research directions related to CoQ metabolism and how the current and novel animal models may help in the development of future research studies.Consejería de Salud, Junta de AndalucíaMinisterio de Universidades, SpainMuscular Dystrophy Association MDA-602322Universidad de GranadaEuropean Regional Development Fund RTI2018-093503-B-100Junta de Andalucía P20_0013

The impact of oil price changes on Spanish and Euro area consumer price inflation

Incluye referencias bibliográficasThis paper assesses the impact of oil price changes on Spanish and euro area consumer price inflation. We find, consistently with recent international evidence, that the inflationary effect of oil price changes is limited, even though crude oil price fluctuations are a major driver of inflation variability. The impact on Spanish inflation is found to be somewhat higher than in the euro area. Direct effects are increasing over time, reflecting the higher spending of households on refined oil products, whereas indirect ones, defined in broad terms, are losing importanc

Bibliografía de los pejerreyes argentinos de agua dulce

Es común la idea de un animal nacional, usado como símbolo, y en general, relacionado con las condiciones naturales dominantes en un país. En el nuestro ha habido varias propuestas que incluyeron aves diversas, en particular al hornero, de virtudes proverbiales, y hasta una humorística, de designar el gran cuis americano (sic), por su valentía que lo lleva a cruzar sin motivo aparente rutas nacionales y provinciales. Más allá de la heráldica, cualquier región natural tiene muchísimas especies que por su monumentalidad, gracia o peculiaridad, son ampliamente conocidas fuera de los círculos científicos. El cóndor, el puma y algunos passeriformes, cumplen estas condiciones. Uno más es el pez al que se refiere esta bibliografía, el pejerrey, Odonthestes bonariensis. A diferencia de otros peces famosos, el pejerrey, considerado excelente para la mesa, es, en la estética de los peces, si tal disciplina existe, un organismo de líneas elegantes y de delicado color plateado. Su morfología, a medias entre la de los órdenes menos y más especializada, es inconfundible. Cualquiera en la Argentina sabe como es un pejerrey, y también que gusto tiene.Facultad de Ciencias Naturales y Muse

Detection of eccentricity faults in five-phase ferrite-PM assisted synchronous reluctance machines

Air gap eccentricity faults in five-phase ferrite-assisted synchronous reluctance motors (fPMa-SynRMs) tend to distort the magnetic flux in the air gap, which in turn affects the spectral content of both the stator currents and the ZSVC (zero-sequence voltage component). However, there is a lack of research works dealing with the topic of fault diagnosis in multi-phase PMa-SynRMs, and in particular, focused to detect eccentricity faults. The analysis of the spectral components of the line currents and the ZSVC, allows developing fault diagnosis algorithms to detect eccentricity faults. The effect of the operating conditions is also analyzed, since this paper shows that it has a non-negligible impact on the effectivity and sensitivity of the diagnosis based on the analysis of the stator currents and the ZSVC. To this end, different operating conditions are analyzed. The paper also evaluates the influence of the operating conditions on the harmonic content of the line currents and the ZSVC, and determines the most suitable operating conditions to enhance the sensitivity of the analyzed methods. Finally, fault indicators to detect eccentricity faults, which are based on the spectral content of the stator currents and the ZSVC are derived, and their performance is assessed. The approach presented in this work may be useful to develop fault diagnosis strategies based on the acquisition and subsequent analysis and interpretation of the spectral content of the line currents and the ZSVC.Peer ReviewedPostprint (published version