La matemática escolar como lenguaje : nuevas perspectivas de investigación y enseñanza

In this article we have made a collection of the focuses and trends in the research on school mathematics considered as a language, which has characterized the research in the 80s and the beginning of the 90s -in contrast with the 70s decade, when the construction of concepts was thought of as the central objective of studying. We also deal -as a matter inherent to research- with the topic of the possible didactic implications that such focus can entail

High field metabolic rates of wild harbour porpoises

This study was partly funded by the German Federal Agency for Nature Conservation (BfN) under the project ‘Under Water Experiments’ (project number FKZ 3515822000) and the BfN Cluster 7 ‘Effects of underwater noise on marine vertebrates’ (Z1.2-53302/2010/14) with additional support to P.T.M. and L.R.-D. from the Danish National Research Foundation (FNU) and the Carlsberg Foundation. B.I.M. was supported by a National Science Foundation International Research Postdoctoral Fellowship (OISE – 1150123). M.J. was supported by the Marine Alliance for Science and Technology Scotland (MASTS) and by a Marie Skłodowska-Curie award.Reliable estimates of field metabolic rates (FMRs) in wild animals are essential for quantifying their ecological roles, as well as for evaluating fitness consequences of anthropogenic disturbances. Yet, standard methods for measuring FMR are difficult to use on free-ranging cetaceans whose FMR may deviate substantially from scaling predictions using terrestrial mammals. Harbour porpoises (Phocoena phocoena) are among the smallest marine mammals, and yet they live in cold, high-latitude waters where their high surface-to-volume ratio suggests high FMRs to stay warm. However, published FMR estimates of harbour porpoises are contradictory, with some studies claiming high FMRs and others concluding that the energetic requirements of porpoises resemble those of similar-sized terrestrial mammals. Here, we address this controversy using data from a combination of captive and wild porpoises to estimate the FMR of wild porpoises. We show that FMRs of harbour porpoises are up to two times greater than for similar-sized terrestrial mammals, supporting the hypothesis that small, carnivorous marine mammals in cold water have elevated FMRs. Despite the potential cost of thermoregulation in colder water, harbour porpoise FMRs are stable over seasonally changing water temperatures. Varying heat loss seems to be managed via cyclical fluctuations in energy intake, which serve to build up a blubber layer that largely offsets the extra costs of thermoregulation during winter. Such high FMRs are consistent with the recently reported high feeding rates of wild porpoises and highlight concerns about the potential impact of human activities on individual fitness and population dynamics.Publisher PDFPeer reviewe

Tropheryma whipplei, the Whipple's disease bacillus, induces macrophage apoptosis through the extrinsic pathway

Tropheryma whipplei, the etiological agent of Whipple's disease, is an intracellular bacterium that infects macrophages. We previously showed that infection of macrophages results in M2 polarization associated with induction of apoptosis and interleukin (IL)-16 secretion. In patients with Whipple's disease, circulating levels of apoptotic markers and IL-16 are increased and correlate with the activity of the disease. To gain insight into the understanding of the pathophysiology of this rare disease, we examined the molecular pathways involved in T. whipplei-induced apoptosis of human macrophages. Our data showed that apoptosis induction depended on bacterial viability and inhibition of bacterial protein synthesis reduced the apoptotic program elicited by T. whipplei. Induction of apoptosis was also associated with a massive degradation of both pro- and anti-apoptotic mediators. Caspase-specific inhibition experiments revealed that initiator caspases 8 and 10 were required for apoptosis, in contrast to caspases 2 and 9, in spite of cytochrome-c release from mitochondria. Finally, the effector caspases 3 and 6 were mandatory for apoptosis induction. Collectively, these data suggest that T. whipplei induces apoptosis through the extrinsic pathway and that, beside M2 polarization of macrophages, apoptosis induction contributes to bacterial replication and represents a virulence trait of this intracellular pathogen

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset

Efficacy of Major Plant Extracts/Molecules on Field Insect Pests

Insect pests are considered the major hurdle in enhancing the production and productivity of any farming system. The use of conventional synthetic pesticides has led to the emergence of pesticide-resistant insects, environmental pollution, and negative effects on natural enemies, which have caused an ecological imbalance of the predator-prey ratio and human health hazards; therefore, eco-friendly alternative strategies are required. The plant kingdom, a rich repertoire of secondary metabolites, can be tapped as an alternative for insect pest management strategies. A number of plants have been documented to have insecticidal properties against various orders of insects in vitro by acting as antifeedants, repellents, sterilant and oviposition deterrents, etc. However, only a few plant compounds are applicable at the field level or presently commercialised. Here, we have provided an overview of the broad-spectrum insecticidal activity of plant compounds from neem, Annona, Pongamia, and Jatropha. Additionally, the impact of medicinal plants, herbs, spices, and essential oils has been reviewed briefl