Blas Cabrera y la física española : ese interesante desconocido.

Se presenta la biografía académica y obra del científico español Blas Cabrera Felipe con el fin de intentar satisfacer el interés del alumnado hacia la historia de la ciencia que, por diversos motivos, no se considera disciplina en España. Se considera una experiencia interdisciplinar entre la física, química e historia que surge a raíz del desconocimiento que tienen los alumnos de ciencias sobre destacados científicos españoles.

El 'Instituto de Canarias Adolfo Cabrera Pinto', de La Laguna. Informe.

Se realiza un repaso por la historia del 'Instituto de Canarias Adolfo Cabrera Pinto' de La Laguna, por ser el edificio más antiguo e importante dentro de la historia de la enseñanza en Canarias.

Blas Cabrera y el descubrimiento del monopolo magnético

Título anterior de la publicación : Boletín de la Comisión Española de la UNESCO

IES Canarias Cabrera Pinto, La Laguna.

Monográfico con el título: 'Historia de un olvido: patrimonio en los centros escolares'. Resumen basado en el de la publicación

La educación es una política social de primer orden : entrevista a Mercedes Cabrera, Ministra de Educación, Política Social y Deporte.

Monográfico con el título: 'Un Consejo más amplio y plural'. Resumen basado en el de la publicación

Literatura y memoria en El monte, de Lydia Cabrera

Este trabajo hace una reflexión acerca de El monte, obra de la autora cubana Lydia Cabrera, publicada en 1954. Se trata de un texto de gran importancia para el folklor y la tradición oral del pueblo cubano, muy en especial para la cultura afrocubana, pues la autora rescató, de los últimos descendientes de los negros de nación, el caudal de leyendas, tradiciones, creencias, magia y supersticiones que estos hombres y mujeres conservaban de la lejana África. Debido a la cuantiosa y diversa información que nos ofrece el libro, es que éste ha sido concebido como texto híbrido, polifónico y heterogéneo que, en correspondencia con sus múltiples facetas escriturarias, ofrece múltiples posibilidades de lecturas. Ante esta disyuntiva, hemos optado por escoger dos entre las numerosas lecturas, la literaria y la de la memoria. En cuanto a la literatura, el trabajo analiza el valor de la obra a partir de los contextos de elaboración y recepción. Lydia elabora el texto como narradora ficcionalizada, cuya voluntad es narrar, hacer grato lo que cuenta, interpretar, dar sentido a los testimonios que ha escuchado de sus informantes, y de la misma forma pueden ser recibidos éstos: tanto el lector familiarizado con los temas como el ajeno a ellos, leen el texto como una ficción que tiene su referente en fenómenos culturales. Por otra parte, al ahondar en la memoria de sus informantes, L. Cabrera se percata de la existencia de una serie de núcleos de resistencia, de ordenamientos secretos que reproducen creencias, tradiciones que datan de la época colonial y se mantienen hasta nuestros días; ellas son las casas- templos en el caso de la Regla de Ocha o Santería y la Regla Conga o de Palo Monte y la Sociedad Secreta Abakuá. Para anoticiarnos de estas instituciones, la escritora explora, en su propio beneficio, tres de las propiedades de la memoria, (variabilidad, selectividad y significación), que le dan sentido a lo escrito. Al finalizar su recorrido por este mundo mágico de los negros, la investigadora nos revela su vinculación espiritual con el objeto de su investigación y su viaje se nos presenta como una verdadera travesía transcultural.

Expression of metallothionein genes I and II in bank vole clethrionomys glareolus populations chronically exposed in situ to heavy metals

The expression of two metallothionein genes (Mt-I and Mt-II) in the liver, kidney, and gonad of bank voles collected at four metal-contaminated sites (Cd, Zn, Pb, and Fe) were measured using the quantitative real-time PCR method (QPCR). Relative Mt gene expression was calculated by applying a normalization factor (NF) using the expression of two housekeeping genes, ribosomal 18S and beta-actin. Relative Mt expression in tissues of animals from contaminated sites was up to 54.8-fold higher than those from the reference site for Mt-I and up to 91.6-fold higher for Mt-II. Mt-II gene expression in the livers of bank voles from contaminated sites was higher than Mt-I gene expression. Inversely, Mt-II expression in the kidneys of voles was lower than Mt-I expression. Positive correlations between cadmium levels in the tissues and Mt-I were obtained in all studied tissues. Zinc, which undergoes homeostatic regulation, correlated positively with both Mt-I and Mt-II gene expression only in the kidney. Results showed that animals living in chronically contaminated environments intensively activate detoxifying mechanisms such as metallothionein expression. This is the first time that QPCR techniques to measure MT gene expression have been applied to assess the impact of environmental metal pollution on field collected bank voles.

Metallothionein I and II gene expression as a response to metal contamination in bank vole Clethrionomys glareolus

The expression of two metallothionein genes (Mt-I and Mt-II) in the liver, kidney, and gonad of bank voles collected at four metal-contaminated sites (Cd, Zn, Pb, and Fe) were measured using the quantitative real-time PCR method (QPCR). Relative Mt gene expression was calculated by applying a normalization factor (NF) using the expression of two housekeeping genes, ribosomal 18S and beta-actin. Relative Mt expression in tissues of animals from contaminated sites was up to 54.8-fold higher than those from the reference site for Mt-I and up to 91.6-fold higher for Mt-II. Mt-II gene expression in the livers of bank voles from contaminated sites was higher than Mt-I gene expression. Inversely, Mt-II expression in the kidneys of voles was lower than Mt-I expression. Positive correlations between cadmium levels in the tissues and Mt-I were obtained in all studied tissues. Zinc, which undergoes homeostatic regulation, correlated positively with both Mt-I and Mt-II gene expression only in the kidney. Results showed that animals living in chronically contaminated environments intensively activate detoxifying mechanisms such as metallothionein expression. This is the first time that QPCR techniques to measure MT gene expression have been applied to assess the impact of environmental metal pollution on field collected bank voles.

How predation and landscape fragmentation affect vole population dynamics

Background: Microtine species in Fennoscandia display a distinct north-south gradient from regular cycles to stable populations. The gradient has often been attributed to changes in the interactions between microtines and their predators. Although the spatial structure of the environment is known to influence predator-prey dynamics of a wide range of species, it has scarcely been considered in relation to the Fennoscandian gradient. Furthermore, the length of microtine breeding season also displays a north-south gradient. However, little consideration has been given to its role in shaping or generating population cycles. Because these factors covary along the gradient it is difficult to distinguish their effects experimentally in the field. The distinction is here attempted using realistic agent-based modelling. Methodology/Principal Findings: By using a spatially explicit computer simulation model based on behavioural and ecological data from the field vole (Microtus agrestis), we generated a number of repeated time series of vole densities whose mean population size and amplitude were measured. Subsequently, these time series were subjected to statistical autoregressive modelling, to investigate the effects on vole population dynamics of making predators more specialised, of altering the breeding season, and increasing the level of habitat fragmentation. We found that fragmentation as well as the presence of specialist predators are necessary for the occurrence of population cycles. Habitat fragmentation and predator assembly jointly determined cycle length and amplitude. Length of vole breeding season had little impact on the oscillations. Significance: There is good agreement between our results and the experimental work from Fennoscandia, but our results allow distinction of causation that is hard to unravel in field experiments. We hope our results will help understand the reasons for cycle gradients observed in other areas. Our results clearly demonstrate the importance of landscape fragmentation for population cycling and we recommend that the degree of fragmentation be more fully considered in future analyses of vole dynamics.

Landscape structure mediates the effects of a stressor on field vole populations

Spatio-temporal landscape heterogeneity has rarely been considered in population-level impact assessments. Here we test whether landscape heterogeneity is important by examining the case of a pesticide applied seasonally to orchards which may affect non-target vole populations, using a validated ecologically realistic and spatially explicit agent-based model. Voles thrive in unmanaged grasslands and untreated orchards but are particularly exposed to applied pesticide treatments during dispersal between optimal habitats. We therefore hypothesised that vole populations do better (1) in landscapes containing more grassland and (2) where areas of grassland are closer to orchards, but (3) do worse if larger areas of orchards are treated with pesticide. To test these hyposeses we made appropriate manipulations to a model landscape occupied by field voles. Pesticide application reduced model population sizes in all three experiments, but populations subsequently wholly or partly recovered. Population depressions were, as predicted, lower in landscapes containing more unmanaged grassland, in landscapes with reduced distance between grassland and orchards, and in landscapes with fewer treated orchards. Population recovery followed a similar pattern except for an unexpected improvement in recovery when the area of treated orchards was increased. Outside the period of pesticide application, orchards increase landscape connectivity and facilitate vole dispersal and so speed population recovery. Overall our results show that accurate prediction of population impact cannot be achieved without taking account of landscape structure. The specifics of landscape structure and habitat connectivity are likely always important in mediating the effects of stressors.

Estudo da densidade populacional do bugio-ruivo Alouatta guariba clamitans (Cabrera, 1940) (Primates, Atelidae) nas formações florestais do Morro Campista, Parque Estadual de Itapuã, Viamão, RS

Resumo não disponível.

Gochnatia polymorpha (Less.) Cabrera (Asteraceae) changes in leaf structure due to differences in light and edaphic conditions

Gochnatia polymorpha (Less.) Cabrera é uma espécie de Asteraceae com ampla distribuição no bioma cerrado, sendo encontrada em diversas fisionomias florestais da região sudeste do Brasil. O presente estudo descreve alguns caracteres anatômicos foliares dessa espécie e os analisa quantitativamente em função de sua ocorrência nas formações florestais e também das diferenças de luminosidade. Foram encontradas diferenças quantitativas em todos os parâmetros anatômicos analisados. Os resultados demonstram que a alta plasticidade anatômica foliar nesta espécie pode ser considerada como uma vantagem adaptativa que a permite ocorrer em diversos ambientes do cerrado.

Aspects of the sexual reproduction of the Brazilian arnica (Solidago chilensis Meyen var. megapotamica (D.C.) Cabrera - Asteraceae)

The species is a very popularly used plant as woundwort. Leaves, top flowers and rhizomes are used. The objective of this work is a contribution to the germination study, photoblastism and more adequate temperature for reproduction of the species. The best temperature for the germination was found to be 20°C and no seeds germinated under continuous darkness, within 14 days; therefore, the seeds are positive photoblastics. The seed germination percentage was low, in relation to the mass of the achene produced, varying from 8,2 to 20,0%. The alternated temperatures of 20° and 30°C did not influence the seed germination and the average of the weight of 100 seeds was 0,026 1 g.

A computer vision approach to quantify leaf anatomical plasticity: A case study on gochnatia polymorpha (less.) cabrera

Inferences about leaf anatomical characteristics had largely been made by manually measuring diverse leaf regions, such as cuticle, epidermis and parenchyma to evaluate differences caused by environmental variables. Here we tested an approach for data acquisition and analysis in ecological quantitative leaf anatomy studies based on computer vision and pattern recognition methods. A case study was conducted on Gochnatia polymorpha (Less.) Cabrera (Asteraceae), a Neotropical savanna tree species that has high phenotypic plasticity. We obtained digital images of cross-sections of its leaves developed under different light conditions (sun vs. shade), different seasons (dry vs. wet) and in different soil types (oxysoil vs. hydromorphic soil), and analyzed several visual attributes, such as color, texture and tissues thickness in a perpendicular plane from microscopic images. The experimental results demonstrated that computational analysis is capable of distinguishing anatomical alterations in microscope images obtained from individuals growing in different environmental conditions. The methods presented here offer an alternative way to determine leaf anatomical differences. © 2013 Elsevier B.V.