1,720,958 research outputs found
La musica racconta Venezia. Canti e balli tra Cinquecento e Settecento
No full textIl volume narra la vita dei veneziani lungo tre secoli , fra '500 e '700, attraverso l'utilizzo della musica. E' organizzato per quadri dedicati a vari aspetti della società veneziana: il carnevale, i mercanti e gli stranieri, la fame, la donna, la religione, la guerra e politica militare, la decadenza
Biodegradative potential of Burkholderia sp. DBT1in the abatement of polycyclic aromatic hydrocarbons
No full textPolycyclic aromatic hydrocarbons (PAHs) tend to accumulate in both anthropized and natural habitats as a result of incomplete combustion of fossil fuels. From the environmental point of view, the main characteristics of PAHs – namely scarce solubility in water, low bio-availability, and high persistence in soil and groundwater – are seriously troublesome. Most PAHs also exert toxic and mutagenic effects and are potentially dangerous to the biological systems. Of the PAHs occurring in soil and groundwater, about 0.04 - 5% (wt/wt) corresponds to sulfur heterocycles. Among these latter, dibenzothiophene (DBT) represents the prevailing compound, which is therefore taken as model chemical structure in studies dealing either with the biodegradation of organo-sulfur contaminants through the “Kodama pathway” or with petroleum bio-desulfurisation through the “4-S pathway”. Since several organic pollutants usually contribute together to the contamination at different sites, isolation and characterization of microorganisms able to degrade a wide range of substrates surely play an important role in the bio-reclamation of polluted areas. Burkholderia sp. DBT1 is a bacterial strain isolated from an oil refinery wastewater which can degrade DBT nearly completely through the “Kodama pathway” within three days. Molecular characterization of the strain DBT1 has shown the presence of an unusual genetic structure. Actually, strain DBT1 genes involved in dibenzothiophene transformation are harbored in two operons and show low similarity to both nah-like and phn-like genes. These particular features encouraged studies aimed at clarifying the possible role of Burkholderia DBT1 in the degradation of PAHs other than condensed thiophenes, frequently occurring in oil-contaminated sites. The growth of strain DBT1 was thus tested in minimal medium supplied with different PAHs. In this way, the strain DBT1 has been demonstrated to efficiently grow on naphthalene, fluorene and phenanthrene. Burkholderia DBT1 has been even proved to degrade 2-carboxybenzaldehyde, phthalic acid and protocatechol, which are common intermediates in the phenanthrene degradation pathway. On the other hand, 2-hydroxy-1-naphthoic acid and 1-hydroxy-2-naphthoic acid – both key intermediates within the two possible upper pathways of phenanthrene degradation – can not function as sole carbon and energy sources for the strain DBT1. RT-PCR analysis and growth tests have been performed with two mutants of Burkholderia DBT1 in order to verify the possible involvement of the two operons already identified in phenanthrene metabolism. Evidence has been gained that the transcription of both operons is activated in presence of phenanthrene. Moreover, the results so far achieved suggest that the strain DBT1 presents a versatile metabolism towards PAHs. This behavior is quite interesting for the possible exploitation of Burkholderia DBT1 in bioremediation protocols of PHA-contaminated sites
Biodiversity amongst cultivable polycyclic aromatic hydrocarbon-transforming bacteria isolated from an abandoned industrial site
No full textThe characterisation of a microbial community of a polycyclic aromatic hydrocarbons (PAHs) contaminated site (formerly Carbochimica, Trento, Italy) was carried out. A preliminary evaluation of the heterogeneity and the metabolic activity of the microbial community were attempted by denaturing gradient gel electrophoresis (DGGE) and reverse transcriptase-denaturing gel electrophoresis (RT-DGGE). The presence of a heterogeneous and metabolically active microbial community was found. To evaluate the PAH-transforming potential of the soil bacterial community, enrichment cultures were set up. Taxonomically diverse bacteria, showing different biochemical PAH-transforming pathways were obtained. Some of the isolates showed not nah-homologous PAH-transforming genotypes
Identification of two new sets of genes for dibenzothiophene transformation in Burkholderia sp. DBT1
No full textA novel genotype for the initial steps of the oxidative degradation of dibenzothiophene(DBT) is described in a Burkholderia sp. strain isolated from a drain receiving oil refinery wastewater. The strain is capable of transforming DBT with significant efficiency when compared to other microorganisms. Its genotype was discovered by investigating insertional mutants of genes involved in DBT degradation by the Kodama pathway. The cloned dbt genes show a novel genomic organization when compared to previously described genes capable of DBT catabolism in that they constitute two distinct operons and are not clustered in a single transcript. Sequence analysis suggests the presence of a sgr54-dependent positive transcriptional regulator that may be involved in the control of the transcription of the two operons, both activated by DBT. The achieved results suggest the possibility of novel features of DBT biotransformation in nature
Isolation of a soil bacterial strain capable of dibenzothiophene degradation
No full textA bacterium belonging to Burkholderia sp., capable of oxidising DBT, has been isolated from toxic sediments contaminated by oil refinery wastewater. The corresponding genetic elements responsible for DBT oxidation has been cloned. The cloned genetic determinants can be classified as a new group of catabolic genes dealing with biodegradation of polycyclic aromatic sulphur-containing heterocycles (PASHs). They are organised in two separate transcriptional units. To the best of our knowledge the data reported here are the first showing a divergent organisation of genes involved in DBT oxidation, and they represent a step forward to understand the prevalence and distribution of the different groups of PASHs catabolic genes that occur in a contaminated soil
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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