A Computational Interpretation of Context-Free Expressions

We phrase parsing with context-free expressions as a type inhabitation problem where values are parse trees and types are context-free expressions. We first show how containment among context-free and regular expressions can be reduced to a reachability problem by using a canonical representation of states. The proofs-as-programs principle yields a computational interpretation of the reachability problem in terms of a coercion that transforms the parse tree for a context-free expression into a parse tree for a regular expression. It also yields a partial coercion from regular parse trees to context-free ones. The partial coercion from the trivial language of all words to a context-free expression corresponds to a predictive parser for the expression

FUEL PROPERTIES OF FOREST RESIDUES RECOVERED FROM FULL EUCALYPTUS TREE HARVESTING IN DIFFERENT CHIP PRODUCTION SCENARIOS

This study aims to evaluate the fuel properties of forest residues recovered from Eucalyptus saligna and E. urophylla × E. grandis stands at seven years old in five chip production scenarios. A forest inventory was conducted to estimate the dry biomass, followed by full-tree harvesting with minimum stem diameters equal to 8, 10, 12, and 14 cm for pulpwood, as well as the full trees for energy purposes (treatments). Moisture, volatile matter, fixed carbon, ash contents, and higher and lower heating values of chips were evaluated. The dry biomass was compared between stands by the t-test (α = 0.05) and the fuel properties were assessed between minimum stem diameters in the same forest stand by the Tukey’s test (α = 0.05). Higher chip moisture was obtained in the larger minimum stem diameter, since it showed an increased up to 88% in moisture for the E. urophylla × E. grandis stand. Volatile matter, fixed carbon, and ash results showed that the recovered residues of E. saligna were more susceptible to variations in minimum stem diameters, with up to 53% reduction in ash content between the smallest diameter and full trees. Higher and lower heating values showed non-statistical differences between the minimum stem diameters in Eucalyptus stands

Characterization of the Polycomb-Group Mark H3K27me3 in Unicellular Algae

Polycomb Group (PcG) proteins mediate chromatin repression in plants and animals by catalyzing H3K27 methylation and H2AK118/119 mono-ubiquitination through the activity of the Polycomb repressive complex 2 (PRC2) and PRC1, respectively. PcG proteins were extensively studied in higher plants, but their function and target genes in unicellular branches of the green lineage remain largely unknown. To shed light on PcG function and modus operandi in a broad evolutionary context, we demonstrate phylogenetic relationship of core PRC1 and PRC2 proteins and H3K27me3 biochemical presence in several unicellular algae of different phylogenetic subclades. We focus then on one of the species, the model red alga Cyanidioschizon merolae, and show that H3K27me3 occupies both, genes and repetitive elements, and mediates the strength of repression depending on the differential occupancy over gene bodies. Furthermore, we report that H3K27me3 in C. merolae is enriched in telomeric and subtelomeric regions of the chromosomes and has unique preferential binding toward intein-containing genes involved in protein splicing. Thus, our study gives important insight for Polycomb-mediated repression in lower eukaryotes, uncovering a previously unknown link between H3K27me3 targets and protein splicing

Enumerations of rooted trees with an application to group presentations

AbstractThe combinatorial properties of the set of rooted trees can be viewed algrebraically by considering this set as an algebra with one unary and one binary operation. This viewpoint yields solutions to several enumeration problems. In particular, using a correspondence between rooted trees and presentations of finite abelian p-groups devised by A.W. Hales, I enumerate all presentations of a given group

PLoS Negl Trop Dis

Zika virus (ZIKV) is a mosquito-borne flavivirus first isolated in Uganda in 1947. Although entomological and virologic surveillance have reported ZIKV enzootic activity in diverse countries of Africa and Asia, few human cases were reported until 2007, when a Zika fever epidemic took place in Micronesia. In the context of West Africa, the WHO Collaborating Centre for Arboviruses and Hemorrhagic Fever at Institut Pasteur of Dakar (|) reports the periodic circulation of ZIKV since 1968. Despite several reports on ZIKV, the genetic relationships among viral strains from West Africa remain poorly understood. To evaluate the viral spread and its molecular epidemiology, we investigated 37 ZIKV isolates collected from 1968 to 2002 in six localities in Senegal and C\uc3\ub4te d'Ivoire. In addition, we included strains from six other countries. Our results suggested that these two countries in West Africa experienced at least two independent introductions of ZIKV during the 20| century, and that apparently these viral lineages were not restricted by mosquito vector species. Moreover, we present evidence that ZIKV has possibly undergone recombination in nature and that a loss of the N154 glycosylation site in the envelope protein was a possible adaptive response to the | vector.|Zika fever is a mosquito-borne illness caused by a flavivirus. Human infections with Zika virus (ZIKV) could cause fever, malaise and cutaneous rash. Despite several ZIKV reports since 1947 when it was first isolated at Zika forest in Uganda, molecular evolution of ZIKV as an emerging agent remains poorly understood. Moreover, despite several ZIKV reports from Africa and Asia, few human cases were notified until 2007 when an epidemic took place in Micronesia. In West Africa, surveillance programs have reported periodic circulation of the virus since 1968. To help fill the gap in understanding ZIKV evolution, 43 ZIKV samples were analyzed. We focused on: (|) adaptive genetic changes including protein glycosylation patterns, (|) phylogenetic relationship among isolates and their spatiotemporal patterns of spread across Africa and Asia and, (|) dispersion among vertebrate reservoirs and invertebrate vector species. Our results indicated that ZIKV may have experienced recombination in nature and that, after it emerged from Uganda in the early of the 20| century, it moved to West Africa and Asia in the first half of the century, without any clear preference for host and vector species

Somatic embryogenesis as an alternative for in vitro multiplication of Butia odorata from mature zygotic embryos

Butia odorata is a palm native to southern Brazil and Uruguay, not domesticated, much appreciated for its fruits and economic potential. However, the extractivism and the diffi culty of propagation have led to the decline of natural populations. The objective of this work was to prove the possibility of induction of somatic embryogenesis in B. odorata. Mature zygotic embryos were induced in two media, MS and Y3, combined with auxin 2,4-D and picloram in fi ve concentrations (2,4-D: 0, 361.99, 452.49, 542.99 and 633.48 μM/L, picloram: 0, 50, 150, 300 and 450 μM/L). The results promising during induction with the formation of embryogenic calli and somatic embryos, however the regeneration of them was not effi cient, this may be due to the occurrence of somatic embryos fused during its development. The roots were formed, but the aerial part remained molten, not completing its development. Auxin picloram and Y3 medium provided the most adequate conditions for calogenesis, formation of embryogenic callus and somatic embryos, with concentrations of 150, 300 and 450 μM/L. This is the fi rst description of somatic embryogenesis in B. odorata that will serve as the basis for future research and adjustments of the methodology proposed here

Sequential Dynamic Classification for Large Scale Multiclass Problems

International audienceExtreme multi-class classification concerns classification problems with very large number of classes, up to several millions. Such problems have now become quite frequent in many practical applications. Until recently, most classification methods had inference complexity at least linear in the number of classes. Several directions have been recently explored for limiting this complexity, but the challenge of learning an optimal compromise between inference complexity and classification accuracy is still largely open. We propose here a novel ensemble learning approach, where classifiers are dynamically chosen among a pre-trained set of classifiers and are iteratively combined in order to achieve an efficient trade-off between inference complexity and classification accuracy. The proposed model uses statistical bounds to discard during the inference process irrelevant classes and to choose the most informative classifier with respect to the information gathered during the previous steps. Experiments on real datasets of recent challenges show that the proposed approach is able to achieve a very high classification accuracy in comparison to baselines and recent proposed approaches for similar inference time complexity