Scattering of slow-light gap solitons with charges in a two-level medium

The Maxwell-Bloch system describes a quantum two-level medium interacting with a classical electromagnetic field by mediation of the the population density. This population density variation is a purely quantum effect which is actually at the very origin of nonlinearity. The resulting nonlinear coupling possesses particularly interesting consequences at the resonance (when the frequency of the excitation is close to the transition frequency of the two-level medium) as e.g. slow-light gap solitons that result from the nonlinear instability of the evanescent wave at the boundary. As nonlinearity couples the different polarizations of the electromagnetic field, the slow-light gap soliton is shown to experience effective scattering whith charges in the medium, allowing it for instance to be trapped or reflected. This scattering process is understood qualitatively as being governed by a nonlinear Schroedinger model in an external potential related to the charges (the electrostatic permanent background component of the field).Comment: RevTex, 14 pages with 5 figures, to appear in J. Phys. A: Math. Theo

Teaching and learning mathematics and statistics at an agricultural engineering school

Postprint (published version

Teaching and learning mathematics and statistics at an Agricultural Engineering School

This paper focuses on the teaching and learning of mathematical topics at the School of Agricultural Engineering of Barcelona in Spain. The teaching and learning process was hindered by under-achievement, absenteeism and lack of motivation on the student’s side. To overcome such obstacles we decided to set to work a new design for the subjects involved with the help of computer and other technologies. Therefore we devised a methodology based on the use of technical tools aiming at solving standard problems and fostering the communication teacher-student. This paper outlines the activities performed to the purpose, depending on the specific contents of each subject matter and the context where they are conducted. However, the use (and misuse) of technology entails some drawbacks, which can be sorted out by means of other kinds of activities, such as lectures, different types of examination questions or the achievement of a project work. Since the implementation of the sketched methodology absenteeism turns out to decrease, whereas students’ motivation seems to improve. In fact students employ statistical tools more frequently than in previous years to fulfil their final degree project. Likewise this methodology contributes to enhance students’ independent work, which matches perfectly the framework of the European Credit Transfer System.Peer Reviewe

Computer assisted assessment through Moodle quizzes for calculus in an Engineering Undergraduate Course

The European Higher Education Area (EHEA) furthers a student-centered system based on the student workload required to achieve the objectives of a study program. In the context of EHEA, e-learning tools provide an outstanding opportunity to discuss mathematical activity in the 21st-century classroom. In 2002, the Technical University of Catalonia (UPC) undertook the use of a virtual teaching tool, the virtual campus Atenea. Since 2005 Atenea has been based on Moodle, an open source learning management system designed to help educators create quality online courses and administer learner outcomes. From the wide range of tools offered by Moodle, we are focusing on the quiz module. This module allows the creation of quizzes with different types of question, adapted to the specific objectives to be reached at any step in the teaching-learning process. Moodle quizzes contribute to the development of new strategies not feasible with paper-and-pencil tests. To explore how to apply these new strategies in the development of a substantial bank of quiz questions, we are carrying out projects subsidised by the Institute of Education Sciences of the UPC. This contribution focuses on the assessment of three Moodle quizzes for Calculus topics that were designed to be answered by around 70 first-year students of the School of Civil Engineering (UPC) in the course 2007/2008. In particular, the aims are to analyse students’ answers and to carry out a psychometric analysis to identify the appropriateness of the questions stated in the quizzes.Peer Reviewe

Agent-based modeling: microbial canibalism

[ES] En un sistema biológico, las interacciones entre los organismos pueden ser interespecíficas, cuando se relacionan organismos de la comunidad de diferente especie, o intraespecíficas. Estas interacciones, que pueden ser favorables, desfavorables o indiferentes para el crecimiento, la supervivencia, y/o la reproducción de los organismos, pueden determinar el área de distribución y la situaci´on territorial de la especie, o tener un papel esencial en la evoluci´on temporal de las poblaciones. Amensalismo, comensalismo, depredación, mutualismo, parasitismo, competencia y canibalismo son diferentes tipos de interacciones. Estas pueden establecerse a lo largo del tiempo y en el espacio, siendo normalmente su ´ámbito de actuación local por proximidad o por contacto directo. Se pueden considerar como propias de las especies o como comportamientos probables, que se pueden dar o no, seg´un como sean las condiciones ambientales en las que se encuentren los organismos. Todo esto hace que la modelizaci´on matemática m´as tradicional sufra de muchas limitaciones en este contexto, tanto para el tratamiento de las discontinuidades en el espacio y el tiempo, como para las adaptaciones o cambios repentinos que pueden sufrir los organismos como respuesta a los diversos factores a los que se puedan ver expuestos. El enfoque o perspectiva de los modelos computacionales basados en agentes (ABM) puede considerarse interesante en la representación de estas interacciones. El propósito de este trabajo es mostrar cómo se puede investigar y tratar con interacciones biológicas a través de ABM. En primer lugar se presentan algunos ejemplos de ABM implementados en un entorno de programación de acceso abierto y disponible desde la web, la plataforma multiagente NetLogo. A continuaci´on, escogida una interacci´on intraespec´ıfica particular, como es el canibalismo microbiano que exhibe la bacteria Bacillus subtilis, se presenta el caso de estudio, con el desarrollo del dise˜no conceptual del ABM para su representación, su implementación en NetLogo, y un análisis de sensibilidad unifactorial de alguno de sus par´ametros para explorar la respuesta del sistema virtual bajo distintos escenarios de simulaci´on. El simulador obtenido ser´a manejado en el entorno académico (su origen fue un Trabajo Final de Grado de la titulación Ingeniería de Sistemas Biológicos de la Universitat Politècnica de Catalunya), será útil tanto en la docencia como para la realización de investigaciones vinculadas con estas interacciones microbianas, abriendo expectativas para futuras aplicaciones prácticas[EN] In a biological system, the interactions between organisms can be interspecific, when they relate organisms of the community of different species, or intraspecific. These interactions, depending on which each case, can be favorable, unfavorable or indifferent to the growth, the survival, and/or the reproduction of the organisms of the affected species, can determine their area of distribution and the territorial situation of the species, or have an essential role in the temporal evolution of the populations. Amensalism, commensalism, depredation, mutualism, parasitism, competition and cannibalism are different types of interactions. These interactions can be established over time and in space, normally their local scope of action is by proximity or direct contact. They can be considered as specific to the species or as probable behaviors, which may or may not occur, depending on the environmental conditions in which the organisms are found. All this means that the more traditional mathematical modeling has many limitations in this context, both for the treatment of discontinuities in space and time, and for adaptations or sudden changes that organisms may suffer as a response to factors to which they may be exposed. The approach or perspective of computational agent-based models (ABM) can be considered interesting in the representation of these interactions. The purpose of this paper is to show how biological interactions can be investigated and treated through ABM. First, some examples of ABM implemented in an open access programming environment and available from the web, the NetLogo multi-agent platform, are presented. Then, choosing a particular intraspecific interaction, such as the microbial cannibalism exhibited by Bacillus subtilis bacteria, the case study is presented, with the development of the conceptual design of the ABM for its representation, its implementation in NetLogo, and a sensitivity analysis unifactorial of some of its parameters to explore the response of the virtual system under different simulation scenarios. The simulator obtained for this study will be employed in an academic setting (its origin was a Final Degree Project in Biological Systems Engineering of the Universitat Polit`ecnica de Catalunya), it will be useful both in teaching and for carrying out research linked to these microbial interactions, opening prospects for future practical applications.Ginovart, M.; Tutusaus, A.; Mas, MT. (2019). Modelización basada en agentes: canibalismo microbiano. Modelling in Science Education and Learning. 12(2):5-46. https://doi.org/10.4995/msel.2019.10975OJS546122Abar, S., Theodoropoulo, G. K., Lemarinier, P., O'Hare, G.M.P. (2017). Agent Based Modelling and Simulation tools: A review of the state-of-art software. Computer Science Review, 24, 13-33. https://doi.org/10.1016/j.cosrev.2017.03.001Araujo, P., Gras, A., Ginovart, M., Moulton, V. (2106). INDISIM-Paracoccus, an individual-based and thermodynamic model for a denitrifying bacterium. Journal of Theoretical Biology, 403, 45-58. https://doi.org/10.1016/j.jtbi.2016.05.017Banitz, T., Gras, A., Ginovart, M. (2015). Individual-based modelling of soil organic matter in NetLogo: Transparent, user-friendly, and open. Environmental Modelling & Software 71, 39-45. https://doi.org/10.1016/j.envsoft.2015.05.007Begon, M., Harper, J.L., Towsend, C.R. (1999). Ecology: Individuals, Populations and Communities. 3a edició. Barcelona: Ediciones Omega. S. A.Deangelis, D.L., Gros, L.J. (1992). Individual-Based Modelos and Approaches in Ecology. Nueva York: Chapman and Hall. https://doi.org/10.1007/978-1-4757-0869-1Font, M., Ginovart, M. (2016). Modelización de crecimientos microbianos en medios heterogéneos y de movilidad reducida. Modelling in Science Education and Learning, 9, 81-120. https://doi.org/10.4995/msel.2016.5789Fujita, M., Gonzalez-Pastor, J.E., Losick, R. (2005). High- and low-threshold genes in the Spo0A regulon of Bacillus subtilis. Journal Bacteriology, 187, 1357-1368. https://doi.org/10.1128/JB.187.4.1357-1368.2005García-Vázquez, J. C., Sancho-Caparrini, F. (2016) NetLogo: Una herramienta de modelado. Payhip. https://payhip.com/b/VhKb.Ginovart, M. (2014). Discovering the power of individual-based modelling in teaching and learning: the study of a predator-prey system. Journal of Science Education and Technology, 23, 496-513. https://doi.org/10.1007/s10956-013-9480-6Ginovart, M. (2015). ¿Qué pueden ofrecer los modelos basados en agentes vivos en el contexto docente? Modelling in Science Education and Learning, 8, 5-26. https://doi.org/10.4995/msel.2015.3486Ginovart, M., Carbó, R., Blanco, M., Portell, X. (2018). Digital image analysis of yeast single cells growing in two different oxygen concentrations to analyze the population growth and to assist individual-based modeling. Frontiers Microbiology, 8, 2628. https://doi.org/10.3389/fmicb.2017.02628Ginovart, M., Portell, X., Ferrer-Closas, P., Blanco, M. (2011). Modelos basados en el individuo y la plataforma NetLogo. Union-Revista Iberoamericana de Educación Matemática, 27, 131-150.Ginovart, M., Portell, X., Ferrer-Closas, P., Blanco, M. (2012) Modelos basados en el individuo: una metodologia alternativa y atractiva para el estudio de biosistemas. Enseñanza de las ciencias, 30, 93-108. https://doi.org/10.5565/rev/ec/v30n2.572González-Cabaleiro, R., Mitchell, A.M., Smith, W., Wipat, A., Ofiteru, I.D. (2017). Heterogeneity in pure microbial systems: experimental measurements and modeling. Frontiers Microbiology, 8, 1813. https://doi.org/10.3389/fmicb.2017.01813González-Pastor, J. E. (2010). Cannibalism: a social behavior in sporulating Bacillus subtilis. FEMS Microbiology Reviews, 35, 415-424. https://doi.org/10.1111/j.1574-6976.2010.00253.xGonzalez-Pastor, J.E., Hobbs, E.C., Losick, R. (2003) Cannibalism by sporulating bacteria. Science, 301, 510-513. https://doi.org/10.1126/science.1086462Gorochowski, T.E. (2016). Agent-based modelling in synthetic biology. Essays in Biochemistry, 60, 325-336. https://doi.org/10.1042/EBC20160037Grimm, V., Railsback, S.F. (2005). Individual-based modelling and ecology. Princeton and Oxford: Princeton University Press. https://doi.org/10.1515/9781400850624Grimm, V., Berger, U., Bastiansen, F., Eliassen, S., Ginot, V., Giske, J., Goss-Custard, J., Grand, T., Heinz, S.K., Huse, G. (2006). A standard protocol for describing individual-based and agent-based models. Ecological Modelling, 198, 115-126. https://doi.org/10.1016/j.ecolmodel.2006.04.023Grimm, V., Berger, U., de Angelis, D.L., Polhill, J.G., Giske, J., Railsback, S.F. (2010).The ODD protocol: A review and first update. Ecological Modelling, 221, 2760-2768. https://doi.org/10.1016/j.ecolmodel.2010.08.019Hellweger. F.L., Bucci, V. (2009). A bunch of tiny individuals - Individual-based modeling for microbes. Ecological Modelling, 220, 8-22. https://doi.org/10.1016/j.ecolmodel.2008.09.004Hellweger, F.L., CLegg, R. J., Clark, J.R., Plugge, C.M., Kreft J. (2016). Advancing microbial sciences by individual-based modelling. Nature Reviews Microbiology, 14. 461-471. https://doi.org/10.1038/nrmicro.2016.62Kaiser, H. (1979). The dynamics of populations as result of the properties of individual animals. Fortschritte der Zoologie, 25, 109-136.Kaul, H., Ventikos, Y. (2015). Investigating biocomplexity through the agent-based paradigm. Briefings in Bioinformatics, 16, 137-152. https://doi.org/10.1093/bib/bbt077López, D., Vlamakis, H., Losick, R., Kolter, R. (2009). Cannibalism enhances biofilm development in Bacillus subtilis. Molecular Microbiology, 74, 609-618. https://doi.org/10.1111/j.1365-2958.2009.06882.xLee, J-S., Filatova, T., Ligmann-Zielinska, A., Hassani-Mahmooei, B., Stonedahl., F., Lorscheid, I., Voinov, A., Polhill, G., Sun, Z., Parker, DC. (2015) The Complexities of Agent-Based Modeling Output Analysis. Journal of Artificial Societies and Social Simulation, 18, 4. https://doi.org/10.18564/jasss.2897Macal, C.M., North, M.J. (2013). Successful approaches for teaching agent-based simulation. Journal of Simulation, 7, 1-11. https://doi.org/10.1057/jos.2012.1Minitab Inc. 2012. Minitab Statistical Software Version 17.2.1. Minitab Inc., State College. PA. URL http://www.minitab.com/.Molle, V., Fujita, M., Jensen, S.T., Eichenberger, P., González-Pastor, J.E., Liu, J.S., Losick, R. (2003). The Spo0A regulon of Bacillus subtilis. Molecular Microbiology, 50, 1683-1701. https://doi.org/10.1046/j.1365-2958.2003.03818.xRailsback, S.F., Grimm, V. (2012) Agent-based and individual-based modeling: a practical introduction. Princeton University Press: Princeton.Ricklefs, R.E. (1998). Invitación a la Ecología. La economía de la naturaleza. 4ª edición. Panamericana: Buenos Aires.Shiflet, A.B., Shiflet, G.W. (2014). An Introduction to Agent-based Modeling for Undergraduates. Procedia Computer Science, 29, 1392-1402.https://doi.org/10.1016/j.procs.2014.05.126Uchmanski, J., Grimm, V. (1996). Individual-based modelling in ecology: What makes the difference? Trends in Ecology & Evolution, 11, 437-440. https://doi.org/10.1016/0169-5347(96)20091-6Wilensky, U. (1997). NetLogo Wolf Sheep Predation model. http://ccl.northwestern.edu/netlogo/models/WolfSheepPredation. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.Wilensky, U. (1997). NetLogo Cooperation model. http://ccl.northwestern.edu/netlogo/models/Cooperation. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.Wilensky. U. (1999). NetLogo. http://ccl.northwestern.edu/netlogo/. Center for Connected Learning and Computer-Based Modeling. Northwestern University. Evanston. IL.Wilensky, U. (2006). NetLogo Tabonuco Yagrumo Hybrid model. http://ccl.northwestern.edu/netlogo/models/TabonucoYagrumoHybrid. Center for Connected Learning and Computer-Based Modeling, Northwestern University, Evanston, IL.Wilensky, U., Rand, W. (2015). An Introduction to Agent-Based Modeling: Modeling Natural, Social, and Engineered Complex Systems with NetLogo. MIT Press: Hong Kong.Wilensky, U., Reisman, K. (2006). Thinking like a Wolf, a Sheep, or a Firefly: Learning Biology through Constructing and Testing Computational Theories - An Embodied Modeling Approach. Cognition and Instruction, 24, 171-209. https://doi.org/10.1207/s1532690xci2402_1Williams, R. A. (2018). Lessons learned on development and application of agent-based models of complex dynamical systems. Simulation Modelling Practice and Theory, 83, 201-212. https://doi.org/10.1016/j.simpat.2017.11.001Wilmoth, J., Doak, P., Timm, A., Halsted, M., Anderson, J.D., Prats, C., Portell, X., Ginovart, M., Retterer, S., Fuentes-Cabrera, M. (2018). A microfluidics and agent-based modeling framework for investigating spatial organization in bacterial colonies: the case of Pseudomonas aeruginosa and Type VI Secretion Interactions. Frontiers Microbiology, 9, 33. https://doi.org/10.3389/fmicb.2018.0003

Curs de càlcul: una nova metodologia per a la impartició i gestió basades en l'entorn Moodle.

El projecte que es presenta, consisteix bàsicament en la elaboració de material docent d’autoaprenentatge utilitzant els diferents recursos de la plataforma Moodle, per tal de desenvolupar un conjunt de temes d’una manera diferent a com es presenten habitualment als estudiants i així poder millorar i consolidar els coneixements de l’estudiant en aquests temes. El desenvolupament del Projecte se centra en titulacions bàsicament tècniques, atesa l’adscripció funcional del professorat que hi ha participat. Tanmateix, per la seva pròpia naturalesa i per la forma a com es tracten els temes, no sembla que hi hagi d’haver especials dificultats per estendre-ho a altres àmbits. Així mateix, s’han tingut molt presents els canvis que sens dubte s’han de produir en la metodologia d’ensenyament de les Matemàtiques en el marc de l’Espai Europeu d’Ensenyament Superior, al qual properament les universitats s’hauran d’adaptar. En tot el Projecte s’ha treballat amb la perspectiva de l’aprenentatge per part de l’estudiant, procurant incrementar la seva motivació i millorar la seva interacció amb temes que considera abstractes i llunyans. Cadascun dels temes comença amb una introducció, desenvolupa les definicions bàsiques, estableix les propietats la metodologia i, en cada pas, s’acompanyen il·lustracions en forma d’exemples, complementades amb exercicis per a l’estudiant.Peer Reviewe

Inadequate Weight Gain According to the Institute of Medicine 2009 Guidelines in Women with Gestational Diabetes: Frequency, Clinical Predictors, and the Association with Pregnancy Outcomes

Background: In the care of women with gestational diabetes mellitus (GDM), more attention is put on glycemic control than in factors such as gestational weight gain (GWG). We aimed to evaluate the rate of inadequate GWG in women with GDM, its clinical predictors and the association with pregnancy outcomes. Methods: Cohort retrospective analysis. Outcome variables: GWG according to Institute of Medicine 2009 and 18 pregnancy outcomes. Clinical characteristics were considered both as GWG predictors and as covariates in outcome prediction. Statistics: descriptive, multinomial and logistic regression. Results: We assessed 2842 women diagnosed with GDM in the 1985-2011 period. GWG was insufficient (iGWG) in 50.3%, adequate in 31.6% and excessive (eGWG) in 18.1%; length of follow-up for GDM was positively associated with iGWG. Overall pregnancy outcomes were satisfactory. GWG was associated with pregnancy-induced hypertension, preeclampsia, cesarean delivery and birthweight-related outcomes. Essentially, the direction of the association was towards a higher risk with eGWG and lower risk with iGWG (i.e., with Cesarean delivery and excessive growth). Conclusions: In this cohort of women with GDM, inadequate GWG was very common at the expense of iGWG. The associations with pregnancy outcomes were mainly towards a higher risk with eGWG and lower risk with iGWG

Creació de qüestionaris des de l'entorn moodle per a assignatures de matemàtiques i estadística corresponents a primers cursos de titulacións d'enginyeria

La finalitat del projecte ha estat el disseny i la implementació d’un banc de 1345 preguntes, que permeten generar col•leccions de qüestionaris, utilitzant les prestacions que ofereix l’entorn Moodle. L’àmbit d’aplicació d’aquests qüestionaris han estat les temàtiques bàsiques i comunes que es troben desenvolupades en la major part d’assignatures de matemàtiques i estadística corresponents als primers cursos de titulacions d’enginyeria. S’han incorporat 161 preguntes d’àlgebra lineal, 769 de càlcul diferencial i integral, 181 d’equacions diferencials ordinàries, i en l’àmbit de probabilitat i estadística, un conjunt de 234 preguntes. Un cop creats aquests bancs de preguntes, s’han creat diversos qüestionaris que responen a nivells de dificultat diferents per a cada una de las matèries que s’han tractat. Això ha permès (i permetrà en el futur) la seva utilització en contextos diferents: proves diagnòstiques de nivell a l‘inici de les assignatures o en començar un tema específic, proves de recapitulació en el transcurs dels mòduls docents, proves d’autoavaluació en hores de treball no presencial, o bé qüestionaris que puguin intervenir en els processos d‘avaluació de les assignatures.Peer Reviewe

EVAM / BASICMATWEB

El projecte consta de dues parts. La primera EVAM (Eina Virtual per a l’Autoaprenentatge de les Matemàtiques) és un conjunt de material interactiu accesible via Web per tal de consolidar i ampliar els coneixements de matemàtiques de l’estudiant. El projecte fa referència a temes de matemàtiques que majoritàriament, l’estudiant ha vist abans d’entrar a la Universitat, però l’experiència ens demostra que el nivell real està, en general, lluny del nivell teòric desitjable. Pels càlculs interactius s’utilitza la plataforma WIRIS. La segona part, que hem anomenat BASICMATWEB, es tracta d’una Web d’ensenyament i autoaprenentatge en xarxa de les Matemàtiques, amb uns continguts que, en general, són els que habitualment s’imparteixen a les assignatures de Matemàtiques del primer curs de les titulacions de la UPC. Per a cada tema hi ha uns resums dels conceptes il•lustrat amb exemples diversos i complementat amb problemes i exercicis que es poden resoldre amb càlculs interactius usant l’eina de compilació WIRIS

Proceso de rotura de una cúpula oval en la catedral de Tortosa. Análisis del mecanismo de colapso

In April of 2011, one of the masonry domes of the cathedral of Tortosa enclosure (Tarragona), built at late XVIII century, suddenly broke. The paper presents the evolution of the rupture and its causes, analyzing the cracking process initiated with the runout of the lantern. It is analyzed the equilibrium conditions starting from the initial constructive assessment in order to know the behavior of the dome and its bearing capacity. There are used complementary traditional graphical methods and tridimensional models by finite elements (FEM) by means of the free software Salome-Meca 6.3. Through the interpretation of the results, the assessment concludes that the dome by itself can hold the weight of the lantern. Thus, the cracking of one of the roof beams causes the bending of the lantern, and therefore the formation of collapse joints from the asymmetrical distribution of loads.En abril del 2011, una de las cúpulas tabicadas del recinto de la catedral de Tortosa (Tarragona), construida a finales del siglo XVIII, rompió repentinamente. El artículo presenta la evolución de la rotura y sus causas, analizando el progresivo proceso de fisuración iniciado con el descentramiento de la linterna. Con el objetivo de conocer el comportamiento de la cúpula y su capacidad portante, se analizan las condiciones de equilibrio a partir del estudio constructivo inicial. Se utilizan de manera complementaria métodos gráficos tradicionales y modelos tridimensionales por elementos finitos (MEF) con el programa libre Salome-Meca 6.3. A partir de la interpretación de los resultados, el estudio concluye que la cúpula por sí sola no tiene capacidad para mantenerse en equilibrio bajo el peso de la linterna. Así el efecto de las termitas sobre la sección de una de las vigas de cubierta provocará el asiento de la linterna y, en consecuencia, la formación de rótulas de colapso a partir de la distribución asimétrica de las cargas