Sobre la formación de los conceptos geométricos y sobre el léxico geométrico

El léxico geométrico está relacionado con un criterio de equivalencia entre figuras -normalmente dado por un grupo de transformación (K1ein) -. Puede haber un conflicto entre el lenguaje ordinario, el léxico geométrico tradicional y el criterio de equivalencia que puede sugerir una situación específica. En este artículo analizamos los resultados de un conjunto de preguntas con el objetivo de descubrir los criterios de equivalencia elegidos por los alumnos de entre 9 y 11 años, y la influencia de su léxico. Hemos observado una influencia considerable de los criterios basados en el grupo de traducciones y en el grupo de homoteties y traducciones. También hemos observado la influencia de ((modelos estándar)) (es decir, figuras que aparecen normalmente en sus libros), y algunas dificultades de conceptualización

Intra-population variation in isotopic niche in herring-eating killer whales off Iceland

Among-individual variation in dietary preferences can impact community dynamics and be a driving force for evolutionary divergence, although it can be difficult to assess in free-ranging marine mammal populations. In this study, we investigate the existence of variation in isotopic niche within a population of putative herring-specialist killer whales. Isotopic ratios of carbon and nitrogen were measured in 67 skin biopsy samples from 56 individual killer whales, sampled in herring overwintering (winter) grounds and spawning (summer) grounds in Iceland when the whales were presumably feeding on herring. Whales that appeared to follow herring year round (n = 31) had lower δ15N values, consistent with a diet predominantly composed of herring. This supports the existence of herring specialists in the population. In contrast, whales that were only photo-identified either in winter or in summer (n = 25) had larger variation in δ15N values. A discriminant function analysis clearly distinguished between putative herring specialists and whales seasonally travelling to Scotland in summer (n = 3), which exhibited distinctly larger δ15N values indicative of a diet including higher trophic level prey. This study shows that herring-eating killer whales in Iceland exhibit intra-population ecological variation, whereby individuals or groups differ in the proportional contribution of different prey items to their diet. This variation occurs in the absence of social and, potentially, reproductive isolation. Although further information will be required to assess the degree of structuring within the population, such heterogeneity should be taken into account in future conservation and management plans

Early Geometrical Thinking in the Environment of Patterns, Mosaics and Isometries

This book discusses the learning and teaching of geometry, with a special focus on kindergarten and primary education. It examines important new trends and developments in research and practice, and emphasizes theoretical, empirical and developmental issues. Further, it discusses various topics, including curriculum studies and implementation, spatial abilities and geometric reasoning, as well as the psychological roots of geometrical thinking and teacher preparation in geometry education. It considers these issues from historical, epistemological, cognitive semiotic and educational points of view in the context of students' difficulties and the design of teaching and curricula

Mapping Cumulative Environmental Risks: Examples from The EU NoMiracle Project

We present examples of cumulative chemical risk mapping methods developed within the NoMiracle project. The different examples illustrate the application of the concentration addition (CA) approach to pesticides at different scale, the integration in space of cumulative risks to individual organisms under the CA assumption, and two techniques to (1) integrate risks using data-driven, parametric statistical methods, and (2) cluster together areas with similar occurrence of different risk factors, respectively. The examples are used to discuss some general issues, particularly on the conventional nature of cumulative risk maps, and may provide some suggestions for the practice of cumulative risk mapping

Retroactive causation and the temporal construction of news: contingency and necessity, content and form

This article affords particular attention to the relationship between memory, the narrativization of news and its linear construction, conceived as journalism’s ‘memory- work’. In elaborating upon this ‘work’, it is proposed that the Hegelian notion of retroactive causation (as used by Slavoj Žižek) can examine how analyses of news journalists ‘retroactively’ employ the past in the temporal construction of news. In fact, such retroactive (re)ordering directs attention to the ways in which journalists contingently select ‘a past’ to confer meaning on the present. With regard to current literature, it is noted that a retroactive analysis can highlight two important dialectics within the practice of news journalism: 1) the relation between contingency and necessity; and, 2) the relation between content and form. Indeed, it is argued that this theoretical account offers a novel approach to examining the significance of memory in news journalism as well as the inconsistencies which underscore journalism’s memory-work. It is in accordance with such inconsistency that broader reflections on time, temporality and our relations to the past can be made

Prenatal Hyperandrogenization Induces Metabolic and Endocrine Alterations Which Depend on the Levels of Testosterone Exposure

Prenatal hyperandrogenism is able to induce polycystic ovary syndrome (PCOS) in rats. The aim of the present study was to establish if the levels of prenatal testosterone may determine the extent of metabolic and endocrine alterations during the adult life. Pregnant Sprague Dawley rats were prenatally injected with either 2 or 5 mg free testosterone (groups T2 and T5 respectively) from day 16 to day 19 day of gestation. Female offspring from T2 and T5 displayed different phenotype of PCOS during adult life. Offspring from T2 showed hyperandrogenism, ovarian cysts and ovulatory cycles whereas those from T5 displayed hyperandrogenism, ovarian cysts and anovulatory cycles. Both group showed increased circulating glucose levels after the intraperitoneal glucose tolerance test (IPGTT; an evaluation of insulin resistance). IPGTT was higher in T5 rats and directly correlated with body weight at prepubertal age. However, the decrease in the body weight at prepubertal age was compensated during adult life. Although both groups showed enhanced ovarian steroidogenesis, it appears that the molecular mechanisms involved were different. The higher dose of testosterone enhanced the expression of both the protein that regulates cholesterol availability (the steroidogenic acute regulatory protein (StAR)) and the protein expression of the transcriptional factor: peroxisome proliferator-activated receptor gamma (PPAR gamma). Prenatal hyperandrogenization induced an anti-oxidant response that prevented a possible pro-oxidant status. The higher dose of testosterone induced a pro-inflammatory state in ovarian tissue mediated by increased levels of prostaglandin E (PG) and the protein expression of cyclooxygenase 2 (COX2, the limiting enzyme of PGs synthesis). In summary, our data show that the levels of testosterone prenatally injected modulate the uterine environment and that this, in turn, would be responsible for the endocrine and metabolic abnormalities and the phenotype of PCOS during the adult life

Toxicity of wine effluents and assessment of a depuration system for their control: assay with tadpoles of Rhinella arenarum (BUFONIDAE)

We evaluated the toxicity of the winery effluent and the efficiency of a symbiotic depuration system by means an experiment with Rhinella arenarum tadpoles. The studied effluent was taken from warehouses during the cleaning season. These effluents subsequently subjected to the purification treatment under evaluation. The effluent samples differentiated into two treatment levels: “raw” where the effluent was evaluated with field conditions and “treated” where the effluent was previously filtered with the symbiotic depuration system. The results of the bioassays compared with the physicochemical parameters determined in the effluent samples. The lethal response had a clear-cut correspondence with the effluent quality assessed utilizing physicochemical parameters. In all cases, dilution of the samples resulted in a significant reduction of their toxicity. It concluded that (a) winery effluents could be harmful to tadpoles of R. arenarum, (b) the symbiotic purification system used to treat wine effluents it would produce a significant reduction in the contaminant levels of the effluent. However, this reduction in contaminant levels does not provide sufficient safety for the release of the effluents into the environment.Fil: Navas Romero, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Herrera Moratta, Mario Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Rodríguez, María Rosa. Universidad Nacional de San Juan. Facultad de Ingeniería; ArgentinaFil: Quiroga, Lorena Beatriz. Universidad Nacional de San Juan. Facultad de Filosofía, Humanidades y Artes. Instituto de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Echegaray, Marcelo Eduardo. Universidad Nacional de San Juan. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Sanabria, Eduardo Alfredo. Universidad Nacional de San Juan. Facultad de Filosofía, Humanidades y Artes. Instituto de Ciencias Básicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; Argentin