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

Apoptosis is increased and cell proliferation is decreased in out-of-phase endometria from infertile and recurrent abortion patients

Various endometrial abnormalities have been associated with luteal phase deficiency: a significant dyssynchrony in the maturation of the glandular epithelium and the stroma and a prevalence of out-of-phase endometrial biopsy specimens. Out-of phase endometrium is a controversial disorder related to failed implantation, infertility and early pregnancy loss. Given that the regulation of the apoptotic process in endometrium of luteal phase deficiency is still unknown, the aim of this study was to evaluate cell proliferation, apoptosis and the levels of the main effector caspase, caspase-3 in the luteal in-phase and out-of-phase endometrium.Fil: Meresman, Gabriela Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Olivares, Carla Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Vighi, Susana. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Alfie, Margarita. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Irigoyen, Marcela. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Etchepareborda, Juan J.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; Argentin

MANEJO DE Amaranthus hybridus EM ÁREA DE INTEGRAÇÃO LAVOURA-PECUÁRIA NA REGIÃO SUL DO RIO GRANDE DO SUL.

A área cultivada com soja aumentou no Brasil nos últimos anos, assim como sua produção total. No Rio Grande do Sul (RS) o cultivo da leguminosa também mostra crescimento, sendo utilizado na sucessão à pecuária de corte no período frio, modelo de produção que contribui para melhor utilização das áreas durante os 12 meses do ano, contribuindo assim para o incremento da renda do produtor, bem como, quando bem manejado, colaborar no manejo integrado de plantas daninhas. Apesar disso, a presença de plantas daninhas dicotiledôneas de difícil controle como Amaranthus hybridus em lavouras de soja do RS vêm aumentando. Assim, o objetivo deste estudo foi avaliar a eficiência de herbicidas pré- e pós-emergentes, e de diferentes programas de manejo para controle de populações de Amaranthus hybridus. O estudo foi composto por quatro experimentos, dois sob condições controladas em casa de vegetação e dois a campo, em uma propriedade rural no município de Cerrito, RS, que integra a produção de soja com pecuária de corte. Os experimentos evidenciaram que alguns biótipos são tolerantes ao glyphosate e aos herbicidas inibidores de ALS (imazethapyr e chlorimuron-ethyl), e que a utilização dos herbicidas pré-emergentes imazethapyr + flumioxazin, metribuzin, s-metolachlor e sulfentrazone + diuron contribui para o manejo destes biótipos. Verificou-se também que a dessecação do azevém e sua complementação com herbicidas de contato e o uso de pré-emergentes são fatores determinantes para o controle de A. hybridus. Ainda, os resultados apontam que em condições de déficit hídrico, a presença de palha prejudica a eficiência de alguns herbicidas pré-emergentes

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

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

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

Defining Chlorophyll-a Reference Conditions in European Lakes

The concept of “reference conditions” describes the benchmark against which current conditions are compared when assessing the status of water bodies. In this paper we focus on the establishment of reference conditions for European lakes according to a phytoplankton biomass indicator—the concentration of chlorophyll-a. A mostly spatial approach (selection of existing lakes with no or minor human impact) was used to set the reference conditions for chlorophyll-a values, supplemented by historical data, paleolimnological investigations and modelling. The work resulted in definition of reference conditions and the boundary between “high” and “good” status for 15 main lake types and five ecoregions of Europe: Alpine, Atlantic, Central/Baltic, Mediterranean, and Northern. Additionally, empirical models were developed for estimating site-specific reference chlorophyll-a concentrations from a set of potential predictor variables. The results were recently formulated into the EU legislation, marking the first attempt in international water policy to move from chemical quality standards to ecological quality targets