Design of a test bench for measuring friction force in a piston-cylinder system

In the present work, design of a first approach of a test bench prototype for measuring friction in a piston-cylinder system is presented. The bench consists of a motor, belt and pulley transmission, crank mechanism, a piston, a cylinder and a lubrication system. Friction will be determined by means of strain gages placed on the connecting rod of the mechanism. The bench also includes a phonic wheel for acquiring angular speed and angular position signals of the crank. In future research, friction will be studied for different surface finishes obtained by means of honing and plateau honing. Honing processes provide a crosshatch pattern that holds oil and helps lubrication of piston and rings. Honing conditions will be selected with the goal of minimizing friction. Friction is directly related to energy consumption of an engine and, thus, to its environmental impact. Keywords: test bench, friction, piston-cylinder system, honing, roughness.Postprint (published version

Cononocimiento del profesor sobre pensamiento estadístico

En este artículo se muestran los diferentes elementos del pensamiento estadístico a través de la práctica de dos profesoras. Dado que se parte de la práctica docente, el marco metodológico es el modelo del cuarteto del conocimiento. Este modelo permite determinar el conocimiento movilizado en una clase a través de las situaciones o tareas que plantea el profesor a sus alumnos. Se describen brevemente los elementos del pensamiento estadístico y su asociación con cada una de las dimensiones del cuarteto a través de diversos episodios de aula al trabajar el tópico de los gráficos estadísticos. Esta recopilación puede constituir una muestra del conocimiento que debe tener un profesor y que puede guiar el diseño de la formación de profesores

Public discourse and debate about vaccines in the midst of the covid-19 pandemic: A qualitative content analysis of Twitter

Objectives: Characterize the public debate and discourse about vaccines during the covid-19 vaccination programmes. Methods: We performed a manual content analysis of a sample of English-written Twitter posts that included the word vaccine and its derivatives. We categorized 7 variables pertaining to the content of the posts, and classified the type of user that published the post and the number of retweets. Then, the patterns of association between these variables were further explored. Results: Among the tweets with negative tone towards vaccines, 33% display negationist discourses, 29% protest or defiance discourses, 13% discuss the pandemic management measures and yet another 13% of these tweets display a scientific discourse. Research results, vaccination data and practical information are more associated to positive tone towards vaccines, while news relate to neutral tone. The users that received more retweets were media accounts and journalists, followed by government accounts and scientific organizations related to the government. Tweets displaying preventive messages received more retweets in average. The discourses most associated with objective information are the preventive, institutional, medical-scientific, and those about the different measures to manage the pandemic. On the other hand, the most subjective tweets are those with negationist, antinegationist and protest discourses. Conclusions: Although there is a non-negligible proportion of tweets that are directly opposed to vaccines, also an important part of vaccine-negative content takes the form of protest discourses, criticisms towards government actions as well as towards the measures to tackle the pandemic. Therefore, negative discourses during the pandemic included serious vaccine hesitancy cases. Moreover, they were not only fuelled by distrust in science, but also and very importantly they were connected to dissatisfaction towards the public management of the pandemic

Comparison between the Performance of Algorithmic Optical Codes and Orthogonal Optical Codes in OCDMA Systems

A novel method to be used in OCDMA systems is exhaustively described in this paper. It uses Algorithmic Optical Codes (AOCs). They are based on the signature sequence idea. However patterns are constantly changing. A common seed for pseudo-random sequence is the signature element. In this paper a derivation of the probability of error due to the multiple-access interference is provided. An other contribution of this work is also the comparison between the AOCs and the Orthogonal Optical Codes (OOCs) with (auto- and cross-) correlation equal to one. Attending to the cardinality limitation problem observed in OOCs, the comparison is focused on the number of users allowed by the two different systems aforementioned. As result we state that a system using AOCs allows more users than one using OOCs when the codes are long enough

Hydrographic conditions and mesozooplankton species distribution in the Bay of Biscay shelf during spring 2004

Mesozooplankton community structure on the southern Bay of Biscay shelf and its relationship with environmental conditions was analysed during spring 2004. According to thermohaline characteristics, we observed two frontal zones along the shelf (around 7° and 3°W) that gave rise to three distinct hydrographic regions. The westernmost part of the shelf (WC), defined by the presence of relatively warm and salty water related to the presence of the Iberian Poleward Current (IPC), the easternmost region (EC), characterised by colder and fresher water, and a region in the Central Cantabrian Sea (CC) with thermohaline characteristics in between these two extremes. Besides, a clear coastal-offshore pattern was found in relation to the mixed layer depth (MLD). We observed a good agreement between the aforesaid hydrographic regions and the distribution of zooplankton species. In the WC region, the community structure was dominated by Paracalanus parvus, Oithona helgolandica, Acartia clausii and Clausocalanus pergens, while in the EC region the most dominant species were Noctiluca scintillans and Oncaea media. The CC region showed similar composition of copepods than the WC region but larvaceans (Oikopleura and Fritilaria) were also abundant. Superimposed to this along-shelf pattern, relative abundances differed also between coastal and shelf stations.SARDYN EU –project (QLRT-2001-00818

Mesozooplankton species distribution in the NW and N Iberian shelf during spring 2004: Relationship with frontal structures.

We have analysed the mesozooplankton community structure in the southern Bay of Biscay shelf and its relationship with the hydrographic conditions during spring 2004. According to thermohaline characteristics, we observed two frontal zones of distinct origin along the shelf (around 7° and 3°W), that allowed us to differentiate three different hydrographic domains. The westernmost part of the shelf (WC), defined by the presence of relatively warm and salty water related to the presence of the Iberian Poleward Current (IPC), the easternmost region (EC), characterized by colder and fresher water and subject to the influence of freshwater inputs from the Adour river in the French coast, and a region in the Central Cantabrian Sea (CC), where thermohaline characteristics were intermediate between these two extremes. The mixing layer depth (MLD) regime in these areas was also different: theWCregion was characterized by a mixed water column, whereas in the EC region the river discharges produces stratification of the upper meters of the water column (b10 m); in the CC region, we found a distinct vertical mixing regime that separated coastal (stratification) from shelf (mixed water column) stations, giving rise to a notorious across-shelf front. We found a good match between the aforesaid hydrographic regions and the distribution of mesozooplankton species composition and community assemblages: the Mantel correlation between physical variables and mesozooplankton distribution was highly significant (n=63, r=0.70, αb0.001). In the WC region, the community was dominated by Paracalanus parvus, Oithona helgolandica, Acartia clausi and Clausocalanus pergens, while in the EC region the most dominant species were Noctiluca scintillans, Oncaea media and Temora longicornis. The CC region showed similar composition of copepods than the WC region, but larvaceans (Oikopleura spp. and Fritillaria spp.) were more abundant in the CC region than in the WC region. Within each zone, the relative abundances of the dominant species differed between coastal and shelf locations.SARDYN EUproject (QLRT-2001-00818) Consejería de Educación y Cultura del Principado de Asturias’ (FICYT)

Influence of News-Finds-Me Perception on accuracy, factuality and relevance assessment. Case study of news item on climate change

Este artículo analiza el efecto de la percepción “las noticias me encuentran” en la evaluación que hace el usuario de una noticia sobre el cambio climático directa e indirectamente a través de aspectos como los hábitos al compartir noticias, los hábitos de consumo de noticias, los usos y gratificaciones en redes sociales, el grado de conocimiento previo y las actitudes previas. Se evalúa asimismo la influencia de estos factores respecto a la decisión de compartir esa noticia. 96 alumnos universitarios españoles rellenaron un cuestionario en el que se les pedía leer y puntuar la calidad de una noticia sobre el cambio climático, e indicar si compartirían esa noticia a través de las redes sociales. Los resultados muestran que los alumnos con una mayor percepción “las noticias me encuentran” tendieron a valorar el artículo como más factual y exacto que aquellos otros con una percepción menor. Por el contrario, no se hallaron diferencias significativas en la evaluación de la relevancia entre los dos grupos. Por tanto, se concluye que la percepción “las noticias me encuentran” reduce las expectativas de los usuarios sobre la calidad, pero no influye en la percepción de la relevancia de la noticia. En cuanto a la intención de compartir la noticia, ningún aspecto considerado en la evaluación influyó en esa decisión.This paper analyses the effect of ‘News-Finds-Me' Perception on the user's assessment of a news item on climate change, both directly and indirectly through news-sharing habits, news-consumption habits, uses and gratifications on social media sites, prior knowledge and attitudes regarding the decision to share said news item. Ninety-six Spanish university students took a survey and were asked to read and rate the quality of a news item on climate change, then to indicate whether they would share that news item on social media. The results show that students with a higher news-finds-me perception tended to rate accuracy and factuality more highly than students with a lower news-finds-me perception. However, relevance was not different between the two groups. Hence, it is concluded that 'News-Finds-Me' Perception lowers the user’s expectations and standards of journalism quality but has no influence on the relevance of the news item. As for sharing intentions, none of the aspects considered in the assessment of the news item had an effect on the decision to share that item.Esta investigación ha sido financiada por el Ministerio de Economía y Competitividad, la Agencia Estatal de Investigación (AEI) y el Fondo Europeo de Desarrollo Regional (FEDER). Referencia CSO2017-86312-R

CaCu3Ti4O12: Pressure dependence of electronic and vibrational structures

The effects of pressure in electronic and vibrational properties of the double perovskite CaCu3Ti4O12 have been investigated in the 0-25 GPa range by optical absorption and Raman spectroscopy. Besides a full structural characterization, we aim at unveiling whether the ambient Im3 crystal structure is stable under high pressure conditions and how its giant dielectric permitivity and electronic gap varies with pressure. Results show that there is evidence of neither structural phase transition nor metallization in CaCu3Ti4O12 in the explored pressure range. We have observed the eight Raman active modes associated with its Im3 crystal phase and obtained their corresponding frequency and pressure shift. Moreover, the direct electronic band gap (2.20 eV), which is mainly associated with the oxygen-to-copper charge transfer states, increases slightly with pressure at a rate of 13 meV GPa?1 from 0 to 10 GPa. Above this pressure is almost constant (Eg = 2.3 eV). The results highlight the high stability of the compound in its Im3 phase against compression.This work has been supported by the Spanish Ministerio de Ciencia, Innovaci´on y Universidades (Projects MAT2015-69508-P, PGC2018-101464-B-I00 and MALTA-Consolider Team RED2018- 102612-T). E.J. thanks for an FPI research grant (Ref. BES-2016-077449)

Un estudio para analizar la violencia contra las niñas en la escuela primaria

En esta ponencia se presenta un estudio1 en el que se ha llevado a cabo con la pretensión de definir y analizar la violencia hacia las niñas en los primeros años de su escolaridad obligatoria (desde 1º a 6º de Educación Primaria, durante el curso 2007-08), ya que en esta etapa es cuando se instauran comportamientos y actitudes que van a determinar sus relaciones como personas adultas. Se ha tratado de describir cuáles son los factores que están incidiendo en las manifestaciones de violencia hacia las niñas (personas, circunstancias, reacciones, modelos de conducta,...) y analizar si mantienen relación con las situaciones que acontecen. Se ha seleccionado una muestra representativa de 644 estudiantes (302 niñas y 342 niños). Como instrumento se ha usado un cuestionario, adaptado a la población del estudio, que consta de 224 cuestiones. El análisis de los datos se ha realizado con el paquete estadístico SPSS-16.0, utilizando, en primer lugar, un análisis descriptivo de los datos, para aplicar posteriormente técnicas estadísticas (prueba chi-cuadrado, tablas de contingencias, test no paramétricos sobre la mediana como el de U-Mann-Whitney) para determinar las diferencias entre grupos de alumnos y alumnas