1,721,033 research outputs found
Light-mediated control of activity in a photosensitive foldamer that mimics an esterase
No full textWe report a catalytic foldamer in which a fumaramide chromophore links a Ser residue to a helical domain that contains within its sequence the residues His and Asp. Photoisomerization of the fumaramide chromophore (withEgeometry) to the corresponding maleamide (withZgeometry) brings together a ‘catalytic triad’ of Ser, His, and Asp, triggering esterase activity that is absent in the fumaramide isomer. The fumaramide/maleamide linker thus acts as a light-sensitive switchable cofactor for activation of catalytic activity in short foldamers
Selection of chlorophyll fluorescence parameters as indicators of photosynthetic efficiency in large scale plant ecological studies
No full textMany morphological, chemical and physiological indicators have been proposed to evaluate the conditions of plants in ecological systems. Among them, the analysis of the prompt fluorescence (PF) of chlorophyll is considered a powerful tool that combines the richness of the achievable information with the operational quickness. This technique is especially suitable in large ecological surveys, where it is required to screen many samples in a brief time. The PF allows evaluating photochemical properties and functionalities of photosynthetic organisms utilizing a set of parameters, known as ‘JIP-test’. The distinct phases of the photochemical processes in terms of energy absorption, trapping and electron transport can be described by these parameters. In this paper, we re-analyse large PF datasets obtained in past researches, carried out in field conditions (forests, plantations and pasture meadows) and in experimental setups (semi-controlled conditions). The aim was to explore the relationships (redundancy and independence) among the JIP-test parameters to select the most suitable ones to capture the variability of plant photosynthetic efficiency and their responses to environmental pressures. The Principal Component Analysis (PCA) was applied to 43,987 measurements. The overall PCA results evidenced that the variability of the PF parameters is explicated mainly by two factors, connected respectively to the processes of photon capture and first photochemical events, and to the efficiency of the electron transport around the photosystem I. This result suggests that, in ecological studies, the photosynthetic functioning of the member of a population can be effectively described with two parameters representative of these two phases: the maximum quantum yield of primary photochemistry of a dark-adapted sample (FV/FM) and the amplitude of the I-P phase (ΔVIP). FV/FM and ΔVIP probed to be independent and their correlation in various datasets may be either positive or negative in relation to the environmental factors considered. The physiological significance of the correlations between these parameters is discussed
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
Salute e vitalità degli ecosistemi forestali: indicatori tradizionali ed innovativi per una valutazione integrata dei boschi cedui (LIFE FutureForCoppiceS)
No full textL’effetto della gestione forestale sostenibile (GFS) è monitorato a livello europeo attraverso l’utilizzo di Criteri di gestione sostenibile, analizzati con specifici indicatori. Nel progetto LIFE FutureForCoppiceS (LIFE14 ENV/IT/000514; http://www.futureforcoppices.eu/it/), indicatori di gestione forestale sostenibile sono applicati per valutare come differenti opzioni di gestione selvicolturale influiscano sulla sostenibilità e l’efficienza dei boschi di origine agamica. Per ogni Criterio, il progetto prevede di utilizzare indicatori consolidati e contestualmente di testare nuovi indicatori.
Per quanto riguarda il Criterio 2 di GFS, relativo a salute e vitalità degli ecosistemi forestali, indicatori consolidati quali defogliazione e danni alle chiome sono stati affiancati da nuovi indicatori scelti per ottenere informazioni più specifiche sullo stato fisiologico e di vitalità degli alberi. A tale scopo sono stati misurati i seguenti tratti fogliari: fluorescenza della clorofilla a, contenuto di clorofilla e parametri di morfologia fogliare. Le misure di questi indicatori sono state effettuate in 21 siti di bosco di origine agamica, appartenenti a tre tipi forestali europei (faggete montane, foreste termofile decidue, foreste di latifoglie sempreverdi) in due regioni italiane (Toscana e Sardegna).
Le prime elaborazioni hanno come obiettivo verificare l’esistenza di relazioni tra indicatori tradizionali ed innovativi, ovvero la possibilità di interpretare i dati di monitoraggio dello stato di salute delle foreste per derivare informazioni ecofisiologiche sulla vitalità e funzionalità delle piante. Più in generale, verrà valutato il potenziale informativo degli indicatori di GFS relativamente alle capacità di resilienza ed adattamento dei boschi cedui ai cambiamenti globali
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