Nonlinear sea level trends from European tide gauge records

International audienceMean sea level is a variable of considerable interest in meteorological and oceanographic studies, particularly long-term sea level variation and its relation to climate changes. This study concerns the analysis of monthly mean sea level data from tide gauge stations in the Northeast Atlantic with long and continuous records. Much research effort on mean sea level studies has been focused on identifying long-term linear trends, usually estimated through least-squares fitting of a deterministic function. Here, we estimate nonparametric and robust trends using lowess, a robust smoothing procedure based on locally weighted regression. This approach is more flexible than a linear trend to describe the deterministic part of the variation in tide gauge records, which has a complex structure. A common trend pattern of reduced sea levels around 1975 is found in all the analysed records and interpreted as the result of hydrological and atmospheric forcing associated with drought conditions at the tide gauge sites. This feature is overlooked by a linear regression model. Moreover, nonlinear deterministic behaviour in the time series, such as the one identified, introduces a bias in linear trends determined from short and noisy records

Multivariate autoregressive modelling of sea level time series from TOPEX/Poseidon satellite altimetry

International audienceThis work addresses the autoregressive modelling of sea level time series from TOPEX/Poseidon satellite altimetry mission. Datasets from remote sensing applications are typically very large and correlated both in time and space. Multivariate analysis methods are useful tools to summarise and extract information from such large space-time datasets. Multivariate autoregressive analysis is a generalisation of Principal Oscillation Pattern (POP) analysis, widely used in the geosciences for the extraction of dynamical modes by eigen-decomposition of a first order autoregressive model fitted to the multivariate dataset of observations. The extension of the POP methodology to autoregressions of higher order, although increasing the difficulties in estimation, allows one to model a larger class of complex systems. Here, sea level variability in the North Atlantic is modelled by a third order multivariate autoregressive model estimated by stepwise least squares. Eigen-decomposition of the fitted model yields physically-interpretable seasonal modes. The leading autoregressive mode is an annual oscillation and exhibits a very homogeneous spatial structure in terms of amplitude reflecting the large scale coherent behaviour of the annual pattern in the Northern hemisphere. The phase structure reflects the seesaw pattern between the western and eastern regions in the tropical North Atlantic associated with the trade winds regime. The second mode is close to a semi-annual oscillation. Multivariate autoregressive models provide a useful framework for the description of time-varying fields while enclosing a predictive potential

Remote Sensing of Aboveground Biomass in Tropical Secondary Forests: A Review

Tropical landscapes are, in general, a mosaic of pasture, agriculture, and forest undergoing various stages of succession. Forest succession is comprised of continuous structural changes over time and results in increases in aboveground biomass (AGB). New remote sensing methods, including sensors, image processing, statistical methods, and uncertainty evaluations, are constantly being developed to estimate biophysical forest changes. We review 318 peer-reviewed studies related to the use of remotely sensed AGB estimations in tropical forest succession studies and summarize their geographic distribution, sensors and methods used, and their most frequent ecological inferences. Remotely sensed AGB is broadly used in forest management studies, conservation status evaluations, carbon source and sink investigations, and for studies of the relationships between environmental conditions and forest structure. Uncertainties in AGB estimations were found to be heterogeneous with biases related to sensor type, processing methodology, ground truthing availability, and forest characteristics. Remotely sensed AGB of successional forests is more reliable for the study of spatial patterns of forest succession and over large time scales than that of individual stands. Remote sensing of temporal patterns in biomass requires further study, in particular, as it is critical for understanding forest regrowth at scales useful for regional or global analyses

Caracterização molecular de Potyvirus que infectam maracujazeiro (Passiflora sp.) no estado da Bahia.

Inúmeras doenças afetam a cultura do maracujazeiro no Brasil, causando grandes prejuízos de ordem econômica, sendo que a virose do endurecimento dos frutos é uma das mais limitantes à produção. Essa doença sempre esteve associada a uma única espécie de Potyvirus, o Passionfruit woodiness virus (PWV). Porém, estudos conduzidos ao longo dos anos demonstraram que mais duas espécies de Potyvirus, o Cowpea aphid-borne mosaicvirus (CABMV) e o East asian passiflora virus (EAPV) também podem causar a mesma doença

Estabelecimento da técnica de RT-PCR para detecção do Citrus tristeza vírus.

A citricultura é uma das mais importantes atividades do agronegócio brasileiro. O Brasil é o maior produtor mundial de citros e a Bahia ocupa o segundo lugar na produção de frutas cítricas brasileiras, que são produzidas, em base familiar, em quase todas as regiões do Estado, o que disponibiliza emprego para cerca de 100 mil trabalhadores na sua cadeia produtiva

Characterizing neuromorphologic alterations with additive shape functionals

The complexity of a neuronal cell shape is known to be related to its function. Specifically, among other indicators, a decreased complexity in the dendritic trees of cortical pyramidal neurons has been associated with mental retardation. In this paper we develop a procedure to address the characterization of morphological changes induced in cultured neurons by over-expressing a gene involved in mental retardation. Measures associated with the multiscale connectivity, an additive image functional, are found to give a reasonable separation criterion between two categories of cells. One category consists of a control group and two transfected groups of neurons, and the other, a class of cat ganglionary cells. The reported framework also identified a trend towards lower complexity in one of the transfected groups. Such results establish the suggested measures as an effective descriptors of cell shape

The dominance of desmids in tropical monomictic lakes (SE Brazil)

Disturbance is a concept used to explain the structure of communities. This concept emphasizes the effects of disturbance on the "break" of biomass stability in stable environments and the opportunities for the development of other species. The major disturbances in natural warm monomictic lakes include the contrasting effects of seasonal changes and long-term in thermal stability, as well as short-term changes in the mixing layer. This study investigated the effects of disturbance and abiotic environmental factors on the biomass of desmids, based on samples collected monthly from January 2002 through December 2006 in the limnetic region of two natural lakes, Carioca (small and shallow) and Dom Helvécio (large and deep), located in Rio Doce State Park, Minas Gerais State,south east Brazil.At Lake Dom Helvécio,the extensive banks of aquatic macrophytes, the lake's dendritic shape and the period of clear water produced higher richness values and facilitated the occurrence of relatively large (maximum linear dimension >20 µm) desmid species, primarily species belonging to Staurastrum and Staurodesmus. In contrast, less richness and a dominant group of relatively small (maximum linear dimension <20 µm) desmid species, especially species belonging to the genus Cosmarium, were observed at Lake Carioca in conjunction with a sparse macrophyte cover. The lakes showed a seasonal thermal stratification characterized by high temperature (25-32ºC), thermal stability and higher desmid biomass. The stability of the epilimnetic desmid biomass was an indicator of the adaptive flexibility of the desmid species and the capacity of the biomass to recover after the mixing period.La perturbación es un concepto utilizado para explicar la estructura de las comunidades, con énfasis en sus efectos sobre la "ruptura" de la estabilidad de la biomasa en ambientes estables y sobre las oportunidades para el desarrollo de nuevas especies. Entre las perturbaciones más importantes encontradas en lagos naturales monomíticos destaca el efecto de las variaciones estacionales y de largo plazo en la estabilidad térmica, así como los cambios a corto plazo en la profundidad de la mezcla. En este trabajo se describe el efecto de la estratificación y mezcla del lago así como de otros factores abióticos sobre la biomasa de desmidiáceas en lagos tropicales. Los muestreos se realizaron mensualmente entre enero de 2002 y diciembre de 2006 en la región pelágica de dos lagos naturales monomíticos cálidos, Carioca (pequeño y poco profundo) y Dom Helvécio (grande y bastante profundo) ubicados en el Parque Estadual do Rio Doce (Estado Minas Gerais, SE Brasil). En el lago Dom Helvécio, las grandes acumulaciones de macrófitas acuáticas, la forma dendrítica del lago y el período de aguas transparentes influyeron de forma sinérgica en una mayor riqueza de especies y de tamaños grandes, mayores de 20 µm, siendo principalmente especies de Staurastrum y Staurodesmus. Sin embargo, en el Lago Carioca se observó una menor riqueza y el dominio de desmidiáceas de pequeño tamaño (<20 µm), especialmente Cosmarium. Este último lago presentó también una cobertura escasa de macrófitas. Los lagos mostraron un patrón estacional caracterizado, durante la estratificación térmica, por el aumento de la temperatura (25-32ºC), estabilidad térmica y mayor biomasa de desmidiáce. La estabilidad de la biomasa epilimnética fue indicativo de una flexibilidad adaptiva y recuperación después del período de mezcla

Microsatellite Markers Isolated From Cabomba Aquatica Sl (cabombaceae) From An Enriched Genomic Library

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Premise of the study: Microsatellite primers were designed for the submersed aquatic plant Cabomba aquatica s.l. (Cabombaceae) and characterized to estimate genetic diversity parameters. Methods and Results: Using a selective hybridization method, we designed and tested 30 simple sequence repeat loci using two natural populations of C. aquatica s.l., resulting in 13 amplifiable loci. Twelve loci were polymorphic, and alleles per locus ranged from two to four across the 49 C. aquatica s.l. individuals. Observed heterozygosity, expected heterozygosity, and fixation index varied from 0.0 to 1.0, 0.0 to 0.5, and -1.0 to -0.0667, respectively, for the Manaus population and from 0.0 to 1.0, 0.0 to 0.6, and -1.0 to 0.4643 for the Virua population. Conclusions: The developed markers will be used in further taxonomic and population studies within Cabomba. This set of microsatellite primers represents the first report on rapid molecular markers in the genus.311Post-Graduate program in Plant Biology of the Instituto de Biologia (UNICAMP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)CAPES [PNADB 457/2010

Viscous Cosmology

We discuss the possibility to implement a viscous cosmological model, attributing to the dark matter component a behaviour described by bulk viscosity. Since bulk viscosity implies negative pressure, this rises the possibility to unify the dark sector. At the same time, the presence of dissipative effects may alleviate the so called small scale problems in the $\Lambda$CDM model. While the unified viscous description for the dark sector does not lead to consistent results, the non-linear behaviour indeed improves the situation with respect to the standard cosmological model.Comment: Latex file, 7 pages, 6 figures. To appear in the proceedings of the XIIth International Conference on Gravitation, Astrophysics and Cosmology, June 28-July 5, 2015, PFUR, Moscow, Russi