1,721,625 research outputs found
Phytoplasma effectors and pathogenicity factors
No full textFor the study and the management of phytoplasma-associated diseases,
the most relevant knowledge needed is the one related to their pathogenicity. After
the availability of full and draft genome sequences of some of the phytoplasmas, a
mining search allowed identifying a number of possible virulence factors. Their
possible pathogenic action was verified mainly by their expression in transgenic
plants such as Arabidopsis spp. and Nicotiana spp. Several possible pathogenicity
factors such as TENGU and SAP11 and/or effector molecules were shown to be
related to metabolic and or phenotypic modifications indistinguishable from those
present in the phytoplasma-infected plants such as phyllody and witches’ broom.
The possible pathogenicity factors or disease effectors studied enclosing extrachromosomal
DNAs, phloem structural modifications, and very recently miRNAs are
also described
F. Press, H. Curien, C. de Benedetti et K. Oshima. A High Technology Gap ? Europe, America and Japan
No full textLabouz Marie-Françoise. F. Press, H. Curien, C. de Benedetti et K. Oshima. A High Technology Gap ? Europe, America and Japan. In: Politique étrangère, n°1 - 1989 - 54ᵉannée. p. 143
Recent Developments in High-Order-Accurate Fluctuation Splitting Schemes
No full textThis paper provides some recent achievements in developing high-order-accurate fluctuation splitting (FS) schemes, by providing a review of some recent developments as well as a novel analysis on Lagrangian elements. The sufficient conditions for an FS scheme to achieve (r + 1)th-order accuracy in both space and time are derived at first. Then, the two suitable approaches for designing third-orderaccurate FS schemes are considered. The gradient based approach is analyzed at first. For a scalar conservation law, a well posed non-compact stable third-orderaccurate FS scheme is designed and validated versus a well known test case. The scheme is then generalized to the case of the Euler equations where, again, it is proven to achieve third-order accuracy in both space and time. The approach based on Lagrangian elements is then analyzed in details, only for the case of scalar advection. The third-order-accurate FS scheme, obtained by exact analytical integration, is shown to be consistent and conservative, but leads to an indeterminate linear system. A useful scheme can be obtained by applying the FS scheme to distribute the residual of each sub cell of the Lagrangian element among its three node
Phytoplasmas: Plant Pathogenic Bacteria - III Genomics, host pathogen interactions, and diagnosis
No full textPhytoplasma-associated diseases are severely limiting the quality and productivity of many ornamental, horticultural and other economically important crops worldwide. Their dangerous impact is economically relevant in sugarcane, sesame, grapevine, fruit trees and coconut palm severely reducing the economic revenues for farmers and stakeholders. There is no effective cure for these diseases therefore the basic knowledge about their biological and biochemical influence on plant and insect vectors are the basic instruments for designing management options aimed to minimize their spread by insect vectors, propagation materials, host plant resistance. The scientific literature concerning genomic, effectors and pathogenicity factors is allowing the understanding of the phytoplasma-host metabolic interaction. It provides comprehensive information on biological, serological and molecular characterization of the phytoplasmas including the recent approaches for diagnostics. Transcriptomics studies paved the way for analyzing the gene expression pattern in phytoplasmas upon infection and revealed the up-regulation of genes associated to hormonal response, transcription factors, and signaling genes. Although phytoplasmas remain the most poorly characterized pathogens, recent studies have identified virulence factors that induce typical disease symptoms and have characterized the unique reductive evolution of the genome. The presentation of the progresses in cultivation in axenic media together with the perspectives for future research that will allow reducing the incidence and the losses due to these pathogens in the agriculture worldwide are also presented. Hence, the major recent research findings are compiled in this book
We greatly acknowledge all the contributed authors for their efforts in synthesizing the most updated reviews on the subjects. We also like to thank the support and input of the publisher, Springer-Nature (Pvt_ Ltd), Singapore, for its effort to publish this book. We strongly hope that it will be useful to everyone interested in phytoplasma research, plant pathology, microbiology, plant biology and agriculture, and serve as an exhaustive and up-to-date reference on various aspects of phytoplasma-associated diseases in order to help the further progress of this branch of the plant pathology scientific knowledge
Multilocus genetic characterization of phytoplasmas
No full textClassification of phytoplasmas into 16S ribosomal groups and subgroups
and ‘Candidatus Phytoplasma’ species designation have been primarily based on
the conserved 16S rRNA gene. However, distinctions among closely related ‘Ca.
Phytoplasma’ species and strains based on 16S rRNA gene alone have limitations
imposed by the high degree of rRNA nucleotide sequence conservation across
diverse phytoplasma lineages and by the presence in a phytoplasma genome of two,
sometimes sequence heterogeneous, copies of this gene. Thus, in recent years, moderately
conserved genes have been used as additional genetic markers with the aim
to enhance the resolving power in delineating distinct phytoplasma strains among
members of some 16S ribosomal subgroups. The present chapter is divided in two
parts: the first part describes the non-ribosomal single-copy genes less conserved
(housekeeping genes) such as ribosomal protein (rp), secY, secA, rpoB, tuf, and
groEL genes, which have been extensively used for differentiation across the majority
of phytoplasmas; the second part describes the differentiation of phytoplasmas
in the diverse ribosomal groups using multiple genes including housekeeping genes
and variable genes encoding surface proteins
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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