Acercar la investigación matemática a las aulas

En este artículo mostramos como la investigación matemática no puede mantenerse alejada de las aulas a riesgo de presentarse a los alumnos y futuros ciudadanos como una ciencia obsoleta y sin aplicaciones en la vida diaria. El Proyecto Klein de IMU e ICMI, que quiere recordar las ideas de principios del siglo XX del matemático alemán Félix Klein, va en esa dirección. Presentamos dos ejemplos posibles en las que, partiendo de resultados elementales que se enseñan en las escuelas, podemos llegar a las últimas aplicaciones y desarrollos sofisticados de la matemática actual

Escherichia coli and its application to biohydrogen production

"Hydrogen is an attractive energy carrier because of its high energy density, and used as a raw material in various chemical processes. Nowadays, hydrogen demand is supplied from non-renewable sources, and alternative sources are becoming mandatory. Hydrogen production by biological methods uses renewable resources as substrate and its production occurs at ambient temperature and atmospheric pressure. Thus, it is less energy intensive than the chemical and thermochemical methods used to produce hydrogen. This review is focused on fermentative hydrogen production by Escherichia coli. The hydrogen production pathway, the genetic manipulations, and expression of non-native pathways into this microorganism are reviewed. The hydrogen production using alternative substrates is a critical point to develop sustainable process by this reason the principal substrates for hydrogen production using E. coli are revised. Other strategies like two stages processes and immobilized cells are also discussed.

Optimal control, contact dynamics and Herglotz variational problem

In this paper, we combine two main topics in mechanics and optimal control theory: contact Hamiltonian systems and Pontryagin maximum principle. As an important result, among others, we develop a contact Pontryagin maximum principle that permits to deal with optimal control problems with dissipation. We also consider the Herglotz optimal control problem, which is simultaneously a generalization of the Herglotz variational principle and an optimal control problem. An application to the study of a thermodynamic system is provided.M. de León and M. Lainz acknowledge the partial finantial support from MINECO Grants MTM2016-76-072-P and PID2019-106715GB-C21 and the ICMAT Severo Ochoa projects SEV2015-0554 and CEX2019-000904-S. M. Lainz wishes to thank MICINN and ICMAT for a FPI-Severo Ochoa predoctoral contract PRE2018-083203. M.C. Muñoz-Lecanda acknowledges the financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades project PGC2018-098265-B-C33 and the Secretary of University and Research of the Ministry of Business and Knowledge of the Catalan Government project 2017–SGR–932. We also thank Maria Barbero-Liñan for the fruitful conversations we had with her about the PMP. Finally, we would like to thank the referees for their careful read and their constructive inputs.Peer ReviewedPostprint (published version

Non-Invasive Forehead Segmentation in Thermographic Imaging

The temperature of the forehead is known to be highly correlated with the internal body temperature. This area is widely used in thermal comfort systems, lie-detection systems, etc. However, there is a lack of tools to achieve the segmentation of the forehead using thermographic images and non-intrusive methods. In fact, this is usually segmented manually. This work proposes a simple and novel method to segment the forehead region and to extract the average temperature from this area solving this lack of non-user interaction tools. Our method is invariant to the position of the face, and other different morphologies even with the presence of external objects. The results provide an accuracy of 90% compared to the manual segmentation using the coefficient of Jaccard as a metric of similitude. Moreover, due to the simplicity of the proposed method, it can work with real-time constraints at 83 frames per second in embedded systems with low computational resources. Finally, a new dataset of thermal face images is presented, which includes some features which are difficult to find in other sets, such as glasses, beards, moustaches, breathing masks, and different neck rotations and flexions

VICARED: A Neural Network Based System for the Detection of Electrical Disturbances in Real Time

The study of the quality of electric power lines is usually known as Power Quality. Power quality problems are increasingly due to a proliferation of equipment that is sensitive and polluting at the same time. The detection and classification of the different disturbances which cause power quality problems is a difficult task which requires a high level of engineering knowledge. Thus, neural networks are usually a good choice for the detection and classification of these disturbances. This paper describes a powerful system for detection of electrical disturbances by means of neural networks

Ostracods as palaeoenvironmental tracers: evolution of the southern area of the Doñana National Park from the lower Pliocene to recent

El estudio de los materiales geológicos y las asociaciones de ostrácodos presentes en un testigo largo obtenido en el sur del Parque Nacional de Doñana (SO de España) permite inferir una evolución paleoambiental desde medios marinos someros (Plioceno Inferior) hasta un lagoon salobre (Pleistoceno Superior-Holoceno) y la implantación de sistemas eólicos (<1.900 años BP), con un estadio intermedio aluvial durante la mayor parte del Pleistoceno. En el Holoceno Superior, se detecta un evento tsunami- génico caracterizado por la erosión de sedimentos eólicos y su depósito sobre medios submarealesThe analysis of the geological units and the ostracod assemblages of a long core collected in the southern Doñana National Park (SW Spain) permits to deduce an evolution from shallow marine palaeoenvironments (Lower Pliocene) to a brackish lagoon (Upper Pleistocene-Holocene) and the deposit of aeolian sediments (<1900 yr BP), with an intermediate alluvial stage during the Pleistocene. In the Late Holocene, a tsunamigenic event was detected, with the erosion of aeolian sediments and a subsequent deposit on subtidal environment

Maximizing hydrogen production and substrate consumption by Escherichia coli WDHL in cheese whey fermentation

"Fermentative hydrogen production is strongly affected by pH. In order to maximize hydrogen production and substrate consumption in Escherichia coli ΔhycA, ΔlacI (WDHL) cheese whey fermentation, the influence of pH control at values of 5.5, 6, and 6.5 was studied in batch stirred-tank bioreactors. From the conditions evaluated, pH 6.5 was the best condition, at which the highest cumulative hydrogen production and yield (1.78 mol H2/mol lactose) were obtained. Moreover, at this pH, all carbohydrates from the cheese whey were consumed, and a mix of ethanol and organic acids, mainly lactate, were produced from glucose, whereas galactose yielded acetate, ethanol, and succinate. Operating the reactor at pH 5.5 resulted in the highest maximum specific production rate, but smaller hydrogen yield because only glucose was metabolized and galactose was accumulated. At pH 6, not all cheese whey carbohydrates were consumed, and it was not favorable for hydrogen production. Lactose consumption and growth kinetics were not affected by the pH. The results show the importance of controlling pH to maximize hydrogen production and substrate consumption using cheese whey as substrate.

Hydrogen production by Escherichia coli ΔhycA ΔlacI using cheese whey as substrate

"This study reports a fermentative hydrogen production by Escherichia coli using cheese whey as substrate. To improve the biohydrogen production, an E. coli ΔhycA ΔlacI strain (WDHL) was constructed. The absence of hycA and lacI genes had a positive effect on the biohydrogen production. The strain produced 22% more biohydrogen in a shorter time than the wild-type (WT) strain. A Box-Behnken experimental design was used to optimize pH, temperature and substrate concentration. The optimal initial conditions for biohydrogen production by WDHL strain were pH 7.5, 37 °C and 20 g/L of cheese whey. The specific production rate was improved from 3.29 mL H2/optical density at 600 nm (OD600nm) unit-h produced by WDHL under non-optimal conditions to 5.88 mL H2/OD600nm unit-h under optimal conditions. Using optimal initial conditions, galactose can be metabolized by WDHL strain. The maximum yield obtained was 2.74 mol H2/mol lactose consumed, which is comparable with the yield reached in other hydrogen production processes with Clostridium sp. or mixed cultures.