2,021 research outputs found
Functional kernel estimators of conditional extreme quantiles
We address the estimation of "extreme" conditional quantiles i.e. when their
order converges to one as the sample size increases. Conditions on the rate of
convergence of their order to one are provided to obtain asymptotically
Gaussian distributed kernel estimators. A Weissman-type estimator and kernel
estimators of the conditional tail-index are derived, permitting to estimate
extreme conditional quantiles of arbitrary order.Comment: arXiv admin note: text overlap with arXiv:1107.226
Inability to decarboxylate lysine as a presumptive marker to identify shiga toxin-producing Escherichia coli strains of serogroup 0111
Universidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilInst Adolfo Lutz Registro, Secao Bacteriol, BR-01246902 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol & Parasitol, BR-04023062 São Paulo, BrazilWeb of Scienc
Microwave hydrothermal synthesis of tobermorite for the solidification of iron
Iron is one of the heavy metals that present in industrial wastewater and domestic waste which damage agricultural production as well as the landscape if there is no proper treatment. One popular method was to introduce the heavy metal ions into the raw material for the synthesis of tobermorite, as the main cement component. However, the conventional hydrothermal synthesis was time and intense energy consuming. Therefore, microwave hydrothermal synthesis of tobermorite was evaluated by comparing with the conventional method. The experimental results showed that the dominant products were Fe-tobermorite/ tobermorite via conventional method, whilst it turned to be Fe-containing hydrogarnet under microwave hydrothermal synthesis when the Fe/Si ratio was 0.15/0.2, which were found to be more stable, thus enhancing the safety of the solidification. Both methods exhibited 100 % of solidification of iron, and the microwave hydrothermal synthesis consumed a much shorter time than conventional method. Therefore, present work has demonstrated that microwave hydrothermal synthesis of tobermorite is an effective alternative to conventional method for the solidification of iron.</p
Localização de transcritos de Bmp-4, Shh e Wnt-5a durante as fases iniciais do desenvolvimento dentário de camundongos por hibridização in situ
A comparative nonisotopic in situ hybridization (ISH) analysis was carried out for the detection of Bmp-4, Shh and Wnt-5a transcripts during mice odontogenesis from initiation to cap stage. Bmp-4 was expressed early in the epithelium and then in the underlying mesenchyme. Shh expression was seen in the odontogenic epithelial lining thickening, being stronger in the enamel knot area, during the cap stage. Wnt-5a transcripts were expressed only in the mesenchyme during the initiation, bud and cap stages, with strong expression in the dental mesenchyme during the bud stage. The present results showed that Bmp-4, Shh and Wnt-5a are expressed since the very early stages of tooth development, and they suggest that the Wnt-5a gene is expressed in different cell populations than Bmp-4 and Shh.No presente trabalho, realizou-se uma análise comparativa não isotópica por hibridização in situ a fim de se detectar a presença de transcritos de Bmp-4, Shh e Wnt-5a durante as fases iniciais da odontogênese em camundongos, desde a iniciação até o estágio de capuz. No estágio de iniciação, observou-se expressão precoce de Bmp-4 no epitélio e no mesênquima subjacente, enquanto que a expressão de Shh ocorreu durante o estágio de capuz, na região de espessamento do revestimento epitelial odontogênico, tornando-se mais intensa na área de nó do esmalte. Os transcritos de Wnt-5a foram expressos somente no mesênquima durante os estágios de iniciação, botão e capuz, com intenso sinal na região no mesênquima na fase de botão. Estes resultados mostraram que Bmp-4, Shh e Wnt-5a são expressos desde os estágios mais precoces do desenvolvimento dentário, sugerindo que o gene Wnt-5a seja expresso em populações celulares distintas daquelas que expressam Bmp-4 e Shh.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)University of São Paulo School of Dentistry Department of Oral PathologyUniversity of São Paulo Biomedical Sciences Institute Department of ImmunologyFederal University of São Paulo Center for Development of Animal ModelsUNIFESP, Center for Development of Animal ModelsSciEL
The biogeographical history of the interaction between mycoheterotrophic Thismia (Thismiaceae) plants and mycorrhizal Rhizophagus (Glomeraceae) fungi
Aim Achlorophyllous mycoheterotrophic plants and mycorrhizal fungi often have highly specific interactions that potentially limit the plants’ distribution and diversification potential. However, specificity in biotic interactions may differ considerably over a species’ distribution range and therefore interactions need to be studied over their entire range to assess their evolution in space and time. The present study investigates the biogeographical history of the interaction between five closely related mycoheterotrophic Thismia species and arbuscular mycorrhizal fungi over the distribution range of the plant species. Location Temperate south-east Australia and New Zealand. Methods Phylogenetic relationships of Thismia (nrITS and mtcob) and their arbuscular mycorrhizal fungi (partial nrSSU) were reconstructed based on data from 65 plant specimens. The diversification times in Thismia were estimated with a Bayesian relaxed clock approach using a Dioscoreales framework (nrSSU, mtatp1, mtmatR, mtnad1 b-c). Ancestral geographical ranges were reconstructed using a maximum likelihood approach. The same approach was used to reconstruct ancestral mycorrhizal associations. Results Our analysis shows that Thismia plants have highly specific, phylogenetically conserved and evolutionarily persistent interactions with Rhizophagus fungi. Nevertheless, Thismia was able to diversify and radiate recently due to the wide geographical distribution of the host fungi. In addition, we find that although the mycorrhizal interactions of this clade of mycoheterotrophs are strictly bound to a fungal lineage, host switches remain possible. Main conclusions In this clade of closely related mycoheterotrophs, dependency on highly specific fungal interactions is the result of phylogenetic niche conservatism, acting over at least 12 million years. Nevertheless, plants that are dependent on highly specific fungal interactions have ample opportunities to disperse and radiate over the geographical range of their hosts. Our study highlights the need to link the ecology and evolution of species interactions over broad geographical and evolutionary scales for understanding mycorrhizal interactions
Entrapment ability and release profile of corticosteroids from starch-based microparticles
We previously described the synthesis of starchbased microparticles that were shown to be bioactive (when combined with Bioactive Glass 45S5) and noncytotoxic. To
further assess their potential for biomedical applications such as controlled release, three corticosteroids with a similar basic structure—dexamethasone (DEX), 16-methylprednisonole
(MP), and 16-methylprednisolone acetate
(MPA) - were used as models for the entrapment and release of bioactive agents. DEX, MP, and MPA were entrapped
into starch-based microparticles at 10% wt/wt of the starch-based polymer and the loading efficiencies, as well as the release profiles, were evaluated. Differences were
found for the loading efficiencies of the three corticosteroids, with DEX and MPA being the most successfully loaded (82 and 84%, respectively), followed by MP (51%). These differences might be explained based on the differential distribution of the molecules within the matrix of the microparticles.
Furthermore, a differential burst release was observed in the first 24 h for all corticosteroids with DEX and MP being
more pronounced (around 25%), whereas only 12% of MPA was released during the same time period. Whereas the water uptake profile can account for this first stage burst
release, the subsequent slower release stage was mainly attributed to degradation of the microparticle network. Differences
in the release profiles can be explained based on the structure of the molecule, because MPA, a more bulky and hydrophobic molecule, is released at a slower rate compared
with DEX and MP. In this work, it is shown that these carriers were able to sustain a controlled release of the entrapped corticosteroids over 30 days, which confirms the potential of these systems to be used as carriers for the delivery of bioactive agents
An efficient semiparametric maxima estimator of the extremal index
The extremal index , a measure of the degree of local dependence in
the extremes of a stationary process, plays an important role in extreme value
analyses. We estimate semiparametrically, using the relationship
between the distribution of block maxima and the marginal distribution of a
process to define a semiparametric model. We show that these semiparametric
estimators are simpler and substantially more efficient than their parametric
counterparts. We seek to improve efficiency further using maxima over sliding
blocks. A simulation study shows that the semiparametric estimators are
competitive with the leading estimators. An application to sea-surge heights
combines inferences about with a standard extreme value analysis of
block maxima to estimate marginal quantiles.Comment: 17 pages, 7 figures. Minor edits made to version 1 prior to journal
publication. The final publication is available at Springer via
http://dx.doi.org/10.1007/s10687-015-0221-
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