El concepto de función: un breve recorrido epistemológico

Puede decirse que uno de los componentes fundamentales en la matemática escolar o especializada de nuestros tiempos es aquel concerniente al concepto de función. Su fragua ha sido el tiempo, y los fraguadores, los actores temporales que lo han moldeado, desde ideas primitivas de relación, pasando por prácticas de modelización de fenómenos naturales, hasta llegar a formar un objeto matemático imprescindible, de belleza única, de mucha sustancia concentrada en definiciones estáticas, que ocultan en sí mismas un impetuoso dinamismo

Spiking buildings to avoid house martin (Delichon urban) nesting: is it a good choice?

Duarte, J., Farfán, M.A.,Vargas, J.M

Distal root curvatures in mandibular molars: analysis using digital panoramic X-rays

Background: The aim of this study was to describe the degree of curvature in distal roots in the first and second permanent mandibular molars in a Chilean patient sample. A cross-sectional descriptive study was conducted in which digital panoramic X-rays were analysed. Materials and methods: Examinations of patients under 18 years, with signs of distortion or alteration in the contrast or the presence of pathologies that affected visualisation of the roots and pulp-chamber floor of the teeth to be analysed were excluded. Using the AutoCad software, an angle was drawn to represent the curve of the root in its different thirds, drawing lines inside the root canal from the pulp-chamber floor to the dental apex. Using the classic definition of dilaceration (root curvature > 90°), its prevalence was established. 412 teeth and roots were analysed, finding a dilaceration prevalence of 0.73% (n = 3). 84.72% of the roots presented some type of curvature. Results: The middle third had the highest percentage of curvatures and the greatest average of angular curvature, whereas the cervical third was the straightest. No significant differences were found between the degree of curvature and the gender of the subjects, except for the apical third of tooth 3.6. The analysis of curvature by root third offers to the clinician a better perspective of the directional change of the roots and does not limit it to just the presence of curves in the apical third. Conclusions: The report of the angular degree of the curvatures, in addition to the prevalence of dilacerations, informs to the clinicians about the likelihood of finding difficulties when treating root canals. (Folia Morphol 2018; 77, 1: 131–137

Landfill habitat restoration can reduce the incidence of vertebrate pest species

Duarte, J., Zurita, F., Farfán, M.A., Vargas, J.M

Land use and environmental factors affecting red-legged partridge (Alectoris rufa) hunting yields in southern Spain

The red-legged partridge is a small game species widely hunted in southern Spain. Its commercial use has important socioeconomic effects in rural areas where other agrarian uses are of marginal importance. The aims of the present work were to identify areas in Andalusia (southern Spain) where game yields for the red-legged partridge reach high values and to establish the environmental and land use factors that determine them. We analysed 32,134 annual hunting reports (HRs) produced by 6,049 game estates during the hunting seasons 1993/1994 to 2001/2002 to estimate the average hunting yields of red-legged partridge in each Andalusian municipality (n=771). We modelled the favourability for obtaining good hunting yields using stepwise logistic regression on a set of climatic, topographical, land use and vegetation variables that were available as digital coverages or tabular data applied to municipalities. Good hunting yields occur mainly in plain areas located in the Guadalquivir valley, at the bottom of Betic Range and in the Betic depressions. Favourable areas are related to highly mechanised, lowelevation areas mainly dedicated to intensive dry crops. The most favourable areas predicted by our model are mainly located in the Guadalquivir valley

Bending collapse analysis for thin and medium-thin-walled square and rectangular hollow shapes

Thin-walled hollow shapes are of great interest in many industries with weight constraints due to their availability, low price, and strength to weight ratio. However, they are also prone to localized bending collapse, which can be used as an energy absorption mechanism during deformation. Up until now, industrial applications have relied on numerical simulations, non-standardized tests, and a handful of theories to address the bending collapse behavior. In this paper, a modification to the most widely used theory is presented and adapted for hollow shapes with greater thickness that cannot be considered. To verify the accuracy of the proposed modification, a comparison with a detailed FEM model, validated through various three-point bending collapse experimental tests, has been performed. The results seem to show that the proposed modifications can predict the maximum load and collapse stage behavior of hollow shapes with more accuracy than the original analytical model. Thus, the proposed modification may be used to predict the collapse behavior of commercially available square and rectangular hollow shapes in different fields of application.D. Lavayen would like to recognize the financial support providedby CONCYTEC (Peru) and The World Bank, through the Pontifical Catholic University of Peru and FONDECYT (Peru): Funding Contract;10-2018-FONDECYT/WB PhD programs in strategic and generalareas. Part of this work has also been supported by Comunidad de Madrid - multiannual agreement with UC3M (Excelencia para el Profesorado Universitario - EPUC3M21 ) - Fifth regional research plan2016-202

Lección de Lingüística. Consideraciones en torno de Ferdinand De Saussure: Asidero de la lingüística actual

Este artículo es una lección de Lingüística. Parte de citas tomadas del Curso de Lingüística general. En este trabajo se reflexiona y se añade principios estructuralistas que, actualmente, son parte de la ciencia del lenguaje. Pretende ser material de una clase básica de Lingüística. No profundiza en conceptos, pero sí los contextualiza. El estilo es sencillo porque se busca el máximo entendimiento posible por parte de estudiantes universitarios

Canales de YouTube de bibliotecas nacionales de la región América Un análisis de videos por categorías

The arrival of 2.0 technologies like the video platform YouTube has caused changes in human behavior, it is a far-reaching audiovisual medium and contains all kinds of audiovisual products, turning it in one of the most popular technologies of the present period. This article examines how National Libraries in the Americas region have turned YouTube in an interesting extension of their services, products and activities, even more so in the COVID-19 crisis. Data is obtained from YouTube channels to have an overview of audiovisual production in this part of the world as the basic characteristics of the channel and the videos. A content analysis is carried out on the videos published in 2020 based on nine categories that are promotion, events, literature, interviews, news, productions, music, film and others. From the results, it is derived that most libraries use the tool, have a large number of videos and subscribers, although it could be improved. Therefore, actions aimed at marketing the library through YouTube are recommended, taking advantage of all its capabilitie

Prevalence and morphometric analysis of idiopathic osteosclerosis in a Chilean population

Background: The aim of this study was to analyse the prevalence and morpho­metric parameters of idiopathic osteosclerosis (IO) in a Chilean population. IO is an intraosseous growth of compact, benign, unilocular, non-expandable bone that is referred to as an anatomical variation. Materials and methods: A cross-sectional study was performed using 1000 digital panoramic radiographs of adults in which data on the location (maxillary/ mandibular, right/left hemiarcades), shape, position to the dental apex, and the prevalence of IOs were observed in relation to gender and age. The morphometric parameters evaluated were area, height, width, and the linear distances of the IO up to the midline and at the base of the mandible. Results: The overall prevalence was 2.8% (27 individuals), with the majority of cases in women (66.7%) in the second, third, and fifth decades of life, but without significant differences. All cases were present in the mandible (100%), usually in the left hemiarcade (59.3%), molar (48.2%) and premolar (44.4%) regions; at the height of the dental apices (65.5%), with an irregular shape (40.7%) and round (37%). The area of the IOs was 33.9 ± 20.1 mm2, with a height of 7.7 ± ± 3.1 mm, width of 6.6 ± 3.1 mm, and the distance from the IO to the mandible median line was 26.6 ± 10.7 mm and 9.7 ± 3.7 mm to the mandibular base. Conclusions: All the data observed corroborate with previous studies; the IO does not present a large difference in the Chilean population evaluated compared to pre­vious studies carried out in other populations. (Folia Morphol 2018; 77, 2: 272–278