Funciones Zeta en los grafos

Se estudian las funciones zeta de Ihara, Hashimoto y Stark asociadas a los vértices aristas y caminos de los grafos finitos, mostrando las relaciones entre ellas, sus propiedades y las fórmulas determinantales que permiten calcularlas. Se demuestra el teorema del número primo para gafos, análogo del teorema del número primo en aritmétrica, mostrando las similitudes ente las funciones zeta de Riemann y de Ihara. Se describen las construcciones recientes de familias infinitas de grafos regulares de Ramanujan bipartitos de cualquier grado.Máster en Investigación en Matemática

Bases en espacios de Banach

En un espacio normado de dimensión infinita las bases algebraicas no son adecuadas, en general, para procesos que involucran un paso al límite. De hecho la prueba de la existencia de tales bases se basa en el lema de Zorn, no siendo, normalmente, posible su construcción, lo que limita de manera notable su utilidad. En este Trabajo de Fin de Grado se trata de estudiar otro tipo de bases, conocidas como bases de Schauder, con las cuales la representación de un vector es obtenida mediante un paso al límite, lo que proporciona una herramienta esencial en el estudio teórico y práctico de los espacios de Banach. Las bases ortonormales en los espacios de Hilbert son un caso particular. Expondremos aquí algunos resultados necesarios para empezar a trabajar con las bases de Schauder.Grado en Matemática

Propuesta de un paseo matemático por Valladolid

El trabajo que aquí se muestra trata de los paseos matemáticos, se ha dividido en cinco capítulos. En el primer capítulo se verá porqué es interesante el paseo matemático como herramienta didáctica, qué objetivos se persigue con este tipo de tareas, como visualizar las matemáticas y cambiar su imagen social y también cómo ha contribuido la realización de este máster para que el trabajo sea más rico en contenido y forma. En el segundo capítulo se verán diversos paseos matemáticos que han sido llevado a cabo por España, en ellos veremos la gran variedad de maneras en la que se puede llevar una actividad para visualizar las matemáticas, desde una ruta divulgativa, hasta una gymkhana. Además, también se expondrá como contribuyen los paseos matemáticos a las siete competencias básicas, es decir, como contribuye a que nuestros alumnos desarrollen todas sus capacidades para que crezcan como personas. El tercer capítulo se ha dedicado al estudio de Valladolid, en él se muestran diversos monumentos, edificios, balcones o figuras que guardan gran relación con las matemáticas. Se mostrarán algunas ideas para poder llevarlo a un aula de secundaria, ya sea como actividad independiente o como parte de un paseo matemático. La cantidad de matemáticas que hay en Valladolid es inmensa, y como es obvio, no se ha podido incluir todo en este trabajo, de modo que está centrado en los lugares del centro de Valladolid y las usadas para elaborar el paseo matemático que se propone. En el cuarto capítulo se lleva a cabo la actividad, un paseo con nueve estaciones y 10 actividades. La actividad se contextualiza en el centro IES José Jiménez Lozano, y para hacer las matemáticas más cercanas aún a los alumnos el paseo empieza en el barrio de Parquesol y acaba en el centro de Valladolid, dejando claro que las matemáticas están por todo Valladolid. El paseo matemático tiene actividades de sobra, y esto es debido a que siempre es mejor que queden cosas por hacer que el quedarse sin materiales. Por último, en el quinto capítulo se escribirán las conclusiones, relativas a los objetivos que marcamos en el trabajo. Se hace también un breve resumen de lo que aporta este trabajo de fin de máster, y se dejan claras cuáles son las líneas de futuro o trabajos de continuación, el más claro de ellos, el llevar este trabajo al aula, cosa que no se pudo hacer durante el periodo de prácticas.Departamento de Didáctica de las Ciencias Sociales y ExperimentalesMáster en Profesor de Educación Secundaria Obligatoria y Bachillerato, Formación Profesional y Enseñanzas de Idioma

Evaluation and improvement of empirical models of global solar irradiation: Case study northern Spain

This paper presents a new methodology to build parametric models to estimate global solar irradiation adjusted to specific on-site characteristics based on the evaluation of variable im- portance. Thus, those variables higly correlated to solar irradiation on a site are implemented in the model and therefore, different models might be proposed under different climates. This methodology is applied in a study case in La Rioja region (northern Spain). A new model is proposed and evaluated on stability and accuracy against a review of twenty-two already exist- ing parametric models based on temperatures and rainfall in seventeen meteorological stations in La Rioja. The methodology of model evaluation is based on bootstrapping, which leads to achieve a high level of confidence in model calibration and validation from short time series (in this case five years, from 2007 to 2011). The model proposed improves the estimates of the other twenty-two models with average mean absolute error (MAE) of 2.195 MJ/m2 day and average confidence interval width (95% C.I., n=100) of 0.261 MJ/m2 day. 41.65% of the daily residuals in the case of SIAR and 20.12% in that of SOS Rioja fall within the uncertainty tolerance of the pyranometers of the two networks (10% and 5%, respectively). Relative differences between measured and estimated irradiation on an annual cumulative basis are below 4.82%. Thus, the proposed model might be useful to estimate annual sums of global solar irradiation, reaching insignificant differences between measurements from pyranometers

Microproject-based teaching/learning methodology focused on emerging technologies and international entities cooperation

[EN] : This paper deals with the implementation of an educational methodology based on microprojects into the subject ‘Manufacturing Technology’ of the EHEA (European Space of Higher Education) engineering degrees. The main idea is to consolidate the theoretical background by working on microprojects ordered by foreign entities. Under this approachstudents implement the theoretical knowledge acquired in the classroom facing real world problems, such as scope definition, planning and team work, while promoting the use of English and information and communication technologies (ICTs). Results show higher motivation and level of interest among students as well as an improvement on their scores when compared with traditional teaching/learning methods.Fernández-Ceniceros, J.; Sanz-García, A.; Antoñanzas-Torres, F.; Alía-Martínez, M.; Pernía-Espinoza, A. (2015). Microproject-based teaching/learning methodology focused on emerging technologies and international entities cooperation. En 1ST INTERNATIONAL CONFERENCE ON HIGHER EDUCATION ADVANCES (HEAD' 15). Editorial Universitat Politècnica de València. 311-318. https://doi.org/10.4995/HEAd15.2015.336OCS31131

Discovery of the elusive carbonic acid (HOCOOH) in space

After a quarter century since the detection of the last interstellar carboxylic acid, acetic acid (CH$_3$COOH), we report the discovery of a new one, the cis-trans form of carbonic acid (HOCOOH), toward the Galactic Center molecular cloud G+0.693-0.027. HOCOOH stands as the first interstellar molecule containing three oxygen atoms and also the third carboxylic acid detected so far in the interstellar medium. Albeit the limited available laboratory measurements (up to 65 GHz), we have also identified several pairs of unblended lines directly in the astronomical data (between 75-120 GHz), which allowed us to slightly improve the set of spectroscopic constants. We derive a column density for cis-trans HOCOOH of $N$ = (6.4 $\pm$ 0.4) $\times$ 10$^{12}$ cm$^{-2}$, which yields an abundance with respect to molecular H$_2$ of 4.7 $\times$ 10$^{-11}$. Meanwhile, the extremely low dipole moment (about fifteen times lower) of the lower-energy conformer, cis-cis HOCOOH, precludes its detection. We obtain an upper limit to its abundance with respect to H$_2$ of $\leq$ 1.2 $\times$10$^{-9}$, which suggests that cis-cis HOCOOH might be fairly abundant in interstellar space, although it is nearly undetectable by radio astronomical observations. We derive a cis-cis/cis-trans ratio $\leq$ 25, consistent with the smaller energy difference between both conformers compared with the relative stability of trans- and cis-formic acid (HCOOH). Finally, we compare the abundance of these acids in different astronomical environments, further suggesting a relationship between the chemical content found in the interstellar medium and the chemical composition of the minor bodies of the Solar System, which could be inherited during the star formation process.Comment: Accepted for publication in The Astrophysical Journa

Risk factors and bronchopulmonary dysplasia severity: data from the Spanish Bronchopulmonary Dysplasia Research Network

GEIDIS is a national-based research-net registry of patients with bronchopulmonary dysplasia (BPD) from public and private Spanish hospitals. It was created to provide data on the clinical characterization and follow-up of infants with BPD until adulthood. The purpose of this observational study was to analyze the characteristics and the impact of perinatal risk factors on BPD severity. The study included 1755 preterm patients diagnosed with BPD. Of the total sample, 90.6% (n = 1591) were less than 30 weeks of gestation. The median gestational age was 27.1 weeks (25.8–28.5) and median birth weight 885 g (740–1,070 g). A total of 52.5% (n = 922) were classified as mild (type 1), 25.3% (n = 444) were moderate (type 2), and 22.2% (n = 389) were severe BPD (type 3). In patients born at under 30 weeks’ gestation, most pre-and postnatal risk factors for type 2/3 BPD were associated with the length of exposure to mechanical ventilation (MV). Independent prenatal risk factors were male gender, oligohydramnios, and intrauterine growth restriction. Postnatal risk factors included the need for FiO 2 of > 0.30 in the delivery room, nosocomial pneumonia, and the length of exposure to MV. Conclusion: In this national-based research-net registry of BPD patients, the length of MV is the most important risk factor associated with type 2/3 BPD. Among type 3 BPD patients, those who required an FiO2 > .30 at 36 weeks’ postmenstrual age had a higher morbidity, during hospitalization and at discharge, compared to those with nasal positive pressure but FiO2 < .30

First glycine isomer detected in the interstellar medium: glycolamide (NH2_2C(O)CH2_2OH)

We report the first detection in the interstellar medium of a C$_2$H$_5$O$_2$N isomer: $syn$-glycolamide (NH$_2$C(O)CH$_2$OH). The exquisite sensitivity at sub-mK levels of an ultra-deep spectral survey carried out with the Yebes 40m and IRAM 30m telescopes towards the G+0.693-0.027 molecular cloud have allowed us to unambiguously identify multiple transitions of this species. We derived a column density of (7.4 $\pm$ 0.7)$\times$10$^{12}$ cm$^{-2}$, which implies a molecular abundance with respect to H$_2$ of 5.5$\times$10$^{-11}$. The other C$_2$H$_5$O$_2$N isomers, including the higher-energy $anti$ conformer of glycolamide, and two conformers of glycine, were not detected. The upper limit derived for the abundance of glycine indicates that this amino acid is surely less abundant than its isomer glycolamide in the ISM. The abundances of the C$_2$H$_5$O$_2$N isomers cannot be explained in terms of thermodynamic equilibrium, and thus chemical kinetics need to be invoked. While the low abundance of glycine might not be surprising, based on the relative low abundances of acids in the ISM compared to other compounds (e.g. alcohols, aldehydes or amines), several chemical pathways can favour the formation of its isomer glycolamide. It can be formed through radical-radical reactions on the surface of dust grains. The abundances of these radicals can be significantly boosted in an environment affected by a strong ultraviolet field induced by cosmic rays, such as that expected in G+0.693-0.027. Therefore, as shown by several recent molecular detections towards this molecular cloud, it stands out as the best target to discover new species with carbon, oxygen and nitrogen with increasing chemical complexity.Comment: Accepted in The Astrophysical Journal Letter

Influence of processing on the volatile profile of strawberry spreads made with isomaltulose

[EN] A new strawberry spread formulated with fructose and isomaltulose (replacing sucrose partially or totally) and a high percentage of fruit was developed in line with the new trend of healthier products. This work studies the influence of some process variables (percentage of sugar, pectin and citric acid, and time of thermal treatment) on the volatile profile of these spreads with different formulations. The ripeness of the raw strawberries influences the concentrations of some of the compounds in the spreads, such as isobutyl acetate, butyl butyrate, 3-hexen-1-yl acetate or propan-2-ol. The process conditions have an important effect on the volatile profiles. Most of the esters and alcohols decreased whereas 13 new compounds appear, mostly furans (furfural, 2-acetylfurane, 5-methyl furfural, mesifurane) and aldehydes (octanal, nonanal, decanal and benzaldeyhde). In general, the spreads formulated with sucrose-isomaltulose that contained higher levels of pectin and citric acid gave better results in the preservation of the original aromatic compounds in raw strawberries.Authors would like to thank Direccion General de Investigacion del Ministerio de Ciencia y Tecnologia (AGL2008-01745/ALI) as well as the Universitat Politecnica de Valencia for the financial support given to this investigation.Peinado Pardo, I.; Rosa Barbosa, EM.; Heredia Gutiérrez, AB.; Escriche Roberto, MI.; Andrés Grau, AM. (2013). Influence of processing on the volatile profile of strawberry spreads made with isomaltulose. Food Chemistry. 138(1):621-629. https://doi.org/10.1016/j.foodchem.2012.09.104S621629138