Concepciones previas en el aprendizaje significativo del electromagnetismo

Difficulties that are present in the basic conceptualizations of electromagnetism are analized. The logic way, followed in physics instruction, which is not necessarily the most adequate to initiate the study of the subject is emphasized. The psychological importance of the previous concepts is also considered. As a consequence the investigation is faced through inquines, obsemations, and data accumulation along the teaching experience on the most frequent preconceptions. The statistical work has been carried out with students of secondary leve1 and university college. As a conclusion subsumers are proposed, which appear as the most adequate to the study of electromagnetism courses content structuration

Distribution of the copia transposable element in the repleta group of Drosophila

The occurrence of the copia transposable element in 18 species of the repleta group of Drosophila has been studied using the Southern technique. The homologous sequence of copia was detected, either with radioactive or non-radioactive nucleic acid detection systems, as a pattern of multiple bands in species of the mercatorum and mulleri subgroups. Nevertheless, this sequence was not detected in the hydei subgroup. The intraspecific polymorphism in the pattern of bands indicates that this sequence is likely to be mobile. Some of the results could suggest the existence of restriction polymorphism of the copia homologous sequence in D koepferae populations. The partial sequencing of two independent clones isolated from D buzzatii clearly establishes that these elements are related and are likely to be the same

Estudio de caso: Conectar Igualdad

The article consists in an overview of the starting, basics, progress, expectations and results around the universal digital inclusion policy of federal scope Conectar Igualdad, initiative which established the distribution of 3.000.000 netbooks between 2010 and 2012 addressed to students and teachers from Argentinean public High Schools, Schools of Special Education and Teacher Training Institutes. Since Decree 459/2010, which gave rise to the project, all the way through the last studies published by the Evaluation and Following team and the delivery of the number 1.000.000 netbook, the article covers the logistic, pedagogic, social and cultural impacts of this Program developing process.El artículo es un recorrido por la creación, los fundamentos, la puesta en marcha, las expectativas y los resultados del programa de inclusión digital de alcance federal Conectar Igualdad, iniciativa que estableció la distribución de 3.000.000 de netbooks en el período 2010-2012 para alumnos y docentes de escuelas secundarias de gestión pública, escuelas de educación especial e institutos de formación docente de la Argentina. Desde el Decreto 459/2010, que le dio origen, hasta los últimos análisis realizados por el equipo de Evaluación y Seguimiento, y en el marco de la entrega de la netbook número 1.000.000, el artículo aborda el impacto logístico, pedagógico, social y cultural de la implementación del Programa

The evolutionary history of Drosophila buzzatii. XVII. Double mating and sperm predominance

Sperm predominance in males and double mating in females have been studied in 2 stocks of the cactophilic species Drosophila buzzatii. The relationship between double mating and total productivity of females was also ascertained. Our results show high values of sperm predominance and double mating. Moreover, female productivity is increased with a second mate. These results are discussed in relation to the mating strategy of this species.On a étudié la prédominance du sperme chez les mâles et le double accouplement chez les femelles dans 2 souches de l'espèce cactophile Drosophila buzzatii. La relation entre le double accouplement et la productivité totale des femelles a été aussi recherchée. Nos résultats montrent des valeurs élevées pour la prédominance du sperme et pour le double accouplement. De plus, on constate que la productivité des femelles est augmentée par un deuxième accouplement. Ces résultats sont discutés par rapport à la stratégie d'accouplement de cette espèce

Breeding structure of Drosophila buzzatii in relation to competition in prickly pears (Opuntia ficus-indica)

International audienc

Osvaldo and Isis retrotransposons as markers of the Drosophila buzzatii colonization in Australia

Background: Transposable elements (TEs) constitute an important source of genetic variability owing to their jumping and regulatory properties, and are considered to drive species evolution. Several factors that are able to induce TE transposition in genomes have been documented (for example environmental stress and inter- and intra-specific crosses) but in many instances the reasons for TE mobilisation have yet to be elucidated. Colonising populations constitute an ideal model for studying TE behaviour and distribution as they are exposed to different environmental and new demographic conditions. In this study, the distribution of two TEs, Osvaldo and Isis, was examined in two colonising populations of D. buzzatii from Australia. Comparing Osvaldo copy numbers between Australian and Old World (reported in previous studies) colonisations provides a valuable tool for elucidating the colonisation process and the effect of new conditions encountered by colonisers on TEs. Results: The chromosomal distributions of Osvaldo and Isis retrotransposons in two colonising populations of D. buzzatii from Australia revealed sites of high insertion frequency (>10%) and low frequency sites. Comparisons between Osvaldo insertion profiles in colonising populations from the Old World and Australia demonstrate a tendency towards a higher number of highly occupied sites with higher insertion frequency in the Old World than in Australian populations. Tests concerning selection against deleterious TE insertions indicate that Isis is more controlled by purifying selection than Osvaldo. The distribution of both elements on chromosomal arms follows a Poisson distribution and there are non-significant positive correlations between highly occupied sites and chromosomal inversions. Conclusions: The occupancy profile of Osvaldo and Isis retrotransposons is characterised by the existence of high and low insertion frequency sites in the populations. These results demonstrate that Australian D. buzzatii populations were subjected to a founder effect during the colonisation process. Moreover, there are more sites with high insertion frequency in the Old World colonisation than in the Australian colonisation, indicating a probable stronger bottleneck effect in Australia. The results suggest that selection does not seem to play a major role, compared to demography, in the distribution of transposable elements in the Australian populations