La axiomatización en la enseñanza secundaria : una opción didáctica

In this article the possibility of using the logic axiomatization of a scientific theory as another tool in the process of learning as a conceptual change is discussed. This way of teaching has to show certain features and ensure that debates in the classroom are centered on the logic connections between deductions. To achieve this the didactic action must give importance to the justification of ideas, debates must be metacognitive and the role of teachers must be more active and diversified. One example of this way of teaching is also introduced herein

Stand dynamics, spatial pattern and site quality in Austrocedrus chilensis forests in Patagonia, Argentina

Aim of study: The objective of this study was to analyze the stand structure and spatial pattern of two A. chilensis stands with contrasting soil conditions and different site qualities in order to explore if these differences lead to patterns similar to the ones observed under different precipitation conditions.Area of study: The study was carried out in two stands located near the city of El Bolsón (41° 56’S - 71° 33’ W), Rio Negro, Argentina.Material and Methods: We evaluated age difference between canopy strata (upper and lower) in two stands with different site qualities by means of a Mann-Whitney test. Dead individuals by diameter class were compared by means of a chi square test. Spatial distribution pattern was analyzed using the pair-correlation function and the mark-correlation function.Main results: Both sites exhibited a random spatial distribution of A. chilensis but different processes seem to underlie the patterns. In the low-quality site facilitation and continuous establishment led to a transient clumped spatial pattern. Mortality mediated by competition occurred mainly on small trees resulting in the current random pattern. On the other hand, spatial pattern in the high-quality site does not reflect a facilitation mediated recruitment. The upper strata established synchronously and subsequent regeneration was episodic.Research highlights: The results show that the differences in site quality may lead to different establishment spatial patterns, showing the importance of facilitation processes in sites with drier soil conditions and lower quality, although results may be site specific, due to the lack of replications.Keywords: Spatial analysis; regeneration; mortality; competition; facilitation.Abbreviations used:  LQ: low-quality site; HQ: high-quality site

Ileum and whole-tract digestibility of carbohydrates contained in a corn- or a sorghum-acorn-based diets fed on finishing Landrace and Iberian pigs

Starch is the storage polysaccharide of higher plants and a major source for animals. However, despite is its simple composition the digestion of starch may be dependent of feed ingredients and animal characteristics

An increased hindgut fermentation promoted major changes on the VFA profile but not on the total VFA concetration of the digesta contents

Volatile fatty acids, principally acetate, propionate and butyrate, are produced in the caecum-colon of pigs as end products of the microbial fermentation. The present abstract tryes to explore on the changes on the VFA concentration and profiles observed in Landrace and Iberian pigs fed on different sources of carbohydrates (high v. low digestible starch)

Aplicaciones basadas en las propiedades eléctricas y térmicas de recubrimientos de sílice-cb obtenidos por el método sol-gel

En los últimos años el interés en los recubrimientos obtenidos por sol-gel ha aumentado mucho en aplicaciones de protección y refuerzo de superficies contra la corrosión. Asimismo, el uso de polimorfos de carbono (nanofibras de carbono, grafeno, grafito...) para mejorar las propiedades mecánicas y conferirle propiedades conductoras a algunos materiales, también se ha desarrollado mucho en los últimos años. En trabajos previos se prepararon y estudiaron recubrimientos híbridos de sílice-CB obtenidos por el método sol-gel. Mediante el estudio de la microestructura y composición de estos recubrimientos (SEM, Raman, ATD-TG, y FT-IR) y de las propiedades eléctricas se obtuvo que en función la temperatura de sinterización de los recubrimientos, se podía controlar la respuesta eléctrica de los composites. Esto permite abrir enormemente el campo de aplicaciones, ya que para temperaturas de sinterización por debajo de 400ºC se consiguen resistividades del orden de 10-4Ωm, apropiadas para aplicaciones en dispositivos electrónicos, electrodos, apantallamiento de interferencias electromagnéticas y radiofreciencia, etc; mientras que para temperaturas de sinterización por encima de 400ºC, obtenemos recubrimientos más resistivos que pueden aplicarse como dispositivos calefactores, anticongelantes. Por tanto, el objetivo de este trabajo es desarrollar más profundamente estas aplicaciones, así como diseñar experimentos que demuestren las múltiples posibilidades que estos recubrimientos conductores obtenidos por sol-gel pueden aportar

Fish under pressure: examining behavioural responses of Iberian barbel under simulated hydropeaking with instream structures

Research ArticleHydropeaking is the rapid change in the water flow downstream of a hydropower plant, driven by changes in daily electricity demand. These fluctuations may produce negative effects in freshwater fish. To minimize these impacts, previous studies have proposed habitat enhancement structures as potential mitigation measures for salmonids. However, the recommendation of these mitigation measures for cyprinids remains scarce and their effects unknown. In this study, the effects of potential habitat mitigation structures under simulated hydropeaking and base-flow conditions are examined for Iberian barbel (Luciobarbus bocagei) in an indoor flume. Solid triangular pyramids and v-shaped structures were evaluated as potential flow-refuging areas and compared with a configuration without structures. A novel, interdisciplinary approach is applied to investigate individual and group responses to rapidly changing flows, by assessing physiological (glucose and lactate), movement behaviour (structure use, sprints and drifts) and the pressure distribution using a fish-inspired artificial lateral line flow sensor. The major findings of this study are four-fold: 1) Under hydropeaking conditions, the v-shaped structures triggered a lactate response and stimulated individual structure use, whereas solid structures did not elicit physiological adjustments and favoured individual and group structure use. Overall, both solid structures and their absence stimulated sprints and drifts. 2) The hydrodynamic conditions created in hydropeaking did not always reflect increased physiological responses or swimming activity. 3) Each event-structure combination resulted in unique hydrodynamic conditions which were reflected in the different fish responses. 4) The most relevant flow variable measured was the pressure asymmetry, which is caused by the vortex size and shedding frequency of the structures. Considering the non-uniform nature of hydropeaking events, and the observation that the fish responded differently to specific flow event-structure combinations, a diverse set of instream structures should be considered for habitat-based hydropeaking mitigation measures for Iberian barbelinfo:eu-repo/semantics/publishedVersio

Detection and identification methods and new tests as developed and used in the framework of cost 873 for bacteria pathogenic to stone fruits and nuts

Xanthomonas arboricola pv. pruni (Xap), the causal agent of bacterial spot disease of stone fruits and almond, is regulated as a quarantine pathogen in the European Union and the European and Mediterranean Plant Protection Organization (EPPO). Xap can have an epiphytic phase and/or be latent and, consequently, it can be transmitted by different types of plant material. Effective quarantine measures require specific, sensitive and rapid methods to detect Xap in propagative material or new reservoirs. Laborious and time-consuming methods for the diagnosis of Xap are recommended in the current EPPO standard protocol. However, new several pathogen-specific PCR and quantitative realtime PCR assays have been developed that enable direct detection of Xap in symptomatic and symptomless plant samples. A concise resource of current methods for Xap detection and identification, based on assessment and development activities within the framework of COST 873, is presented

Extensions of discrete classical orthogonal polynomials beyond the orthogonality

It is well known that the family of Hahn polynomials $\{h_n^{\alpha,\beta}(x;N)\}_{n\ge 0}$ is orthogonal with respect to a certain weight function up to $N$. In this paper we present a factorization for Hahn polynomials for a degree higher than $N$ and we prove that these polynomials can be characterized by a $\Delta$-Sobolev orthogonality. We also present an analogous result for dual-Hahn, Krawtchouk, and Racah polynomials and give the limit relations between them for all n\in \XX N_0. Furthermore, in order to get this results for the Krawtchouk polynomials we will get a more general property of orthogonality for Meixner polynomials.Comment: 2 figures, 20 page

Glioblastoma with primitive neuronal component: A case report and considerations of fluorescence-guided surgery

Background: Glioblastoma with primitive neuronal components (GB/PNC) is an extremely rare type of glioblastoma characterized by presenting histological and cytogenetic features of both entities. The mixed nature of these tumors limits the imaging diagnosis and supposes a therapeutic dilemma. Case Description: We present the case of a 77-year-old female with a GB/PNC who is treated with surgery and adjuvant radiochemotherapy according to the STUPP protocol, where an abnormal uptake of 5-aminolevulinic acid (5-ALA) is evident during surgery in probable relation to the mixed nature of GB/PNC. Conclusion: GB/PNC is extremely rare tumors. Given its low prevalence, there are no studies that refer to the macroscopic characteristics of the tumor as well as evidence of the effectiveness of adjuvant treatment. Fluorescence-guided resection with 5-ALA is the surgical treatment of choice in surgery for high-grade gliomas; however, in GB/PNC, it may not be as useful since PNC may have less fluorescent marker uptake and be more dimly visualized when excited by light using the surgical microscope