1,720,966 research outputs found
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
LONG-DISTANCE TURGOR CHANGES INDUCE SYSTEMIC ACTIVATION OF PLANT GLUTAMATE RECEPTOR-LIKE CHANNELS
Get PDFNel corso della loro vita le piante, essendo organismi sessili, sono continuamente soggette a cambiamenti ambientali che necessitano di essere accuratamente percepiti, a cui devono seguire appropriate risposte sia a livello locale che sistemico che ne garantiscano la sopravvivenza. Il calcio (Ca2+) è uno ione che agisce come importante secondo messaggero in tutti gli esseri viventi, in grado di accoppiare la percezione di uno stimolo extracellulare a peculiari risposte intracellulari. La specificità di trasduzione del segnale basata sul Ca2+ è ottenuta grazie alla generazione di transienti incrementi della sua concentrazione citosolica ([Ca2+]cyt), specifici nella loro evoluzione spaziale e temporale, alla quale ci si riferisce come “Ca2+ signatures”. La decodifica delle “Ca2+ signatures” da parte di proteine capaci di legare il Ca2+ permette la messa in atto di appropriate risposte fisiologiche. Nelle piante, è stato documentato che transienti variazioni citosoliche di Ca2+ sono coinvolte in svariati processi fisiologici che includono lo sviluppo della radice, lo sviluppo del tubetto pollinico e il processo di fecondazione, la risposta a stress abiotici, la regolazione dell’interazione pianta-microbo. Transienti incrementi nella [Ca2+]cyt con caratteristica intensità, frequenza, dinamica e durata sono generati dalla azione orchestrata di sistemi di influsso ed efflusso del Ca2+, che includono canali, pompe e scambiatori del Ca2+ che sono localizzati a livello delle membrane cellulari. Data l’importanza e l’universalità della trasduzione del segnale basata sul Ca2+, risulta essere di primaria importanza l’identificazione degli attori molecolari che governano la generazione dei segnali Ca2+. In questo contesto, lo studio delle dinamiche del Ca2+ in vivo rappresenta un potente strumento investigativo.
Nel corso del mio dottorato di ricerca, ho esplorato il meraviglioso mondo del “Ca2+ imaging” utilizzando il vasto universo di Biosensori fluorescenti per il Ca2+ geneticamente codificati. Ho appreso e affinato tecniche per produrre immagini di alta qualità rappresentative di dinamiche del Ca2+ in vivo, sia a livello di intero organismo che a singola cellula. Le competenze che ho acquisito mi hanno permesso di contribuire a vari progetti tutti accomunati da quello che è un comune denominatore, ovvero il ruolo cardine del Ca2+ nella regolazione di svariati processi di trasduzione del segnale. Mi sono avventurato nello studio di vari aspetti legati alla segnalazione del Ca2+ tra cui: (i) gli aumenti della [Ca2+]cyt indotti nelle cellule dell’apice radicale in risposta a differenti amminoacidi, contribuendo a definire i determinanti molecolari sottostanti a tali risposte (Alfieri et al., 2020); (ii) la caratterizzazione dei transienti incrementi della [Ca2+]cyt indotti da auxine naturali e da molecole analoghe dell’auxina, e la decifrazione del ruolo di alcuni attori molecolari coinvolti nella genesi delle risposte [Ca2+]cyt indotte da auxina (Wang, Himschoot, Grenzi et al., 2022); (iii) lo sviluppo di un nuovo biosensore per il Ca2+ geneticamente codificato per indagare il ruolo del reticolo endoplasmico nella modellazione delle “Ca2+ signatures” in processi di sviluppo, così come in risposta a vari stimoli (Resentini, Grenzi et al., 2021); (iv) l’effetto di modulazione che alcuni composti chimici hanno sulle oscillazioni spontanee nella [Ca2+]cyt delle cellule di guardia che governano l’apertura e la chiusura degli stomi. Ho inoltre contribuito alla scrittura di reviews legate al mondo del “Ca2+ signalling” in pianta. Tutti i lavori pubblicati, così come i lavori in preparazione, sono allegati al termine di questa dissertazione, alla quale rimando gentilmente il lettore. Qui presenterò il lavoro portato avanti nel contesto del mio progetto di dottorato, il quale si è focalizzato principalmente alla comprensione dei meccanismi rapidi di segnalazione a lunga distanza.
Le risposte sistemiche sono governate da eventi di segnalazione a lunga distanza che richiedono l’attività dei Recettori del Glutammato (GLRs). I GLRs sono proteine omologhe ai Recettori del Glutammato animali (iGluRs), ovvero canali ionici attivati da ligando presenti nel sistema nervoso centrale. Nonostante negli animali è chiaro che gli iGluRs mediano il passaggio di ioni a seguito del loro legame con il L-Glutammato, il meccanismo attraverso cui i GLRs sono attivati in pianta è ancora largamente discusso. Ad esempio, non si è ancora a conoscenza se il legame dell’aminoacido ai GLRs sia realmente necessario per la loro attivazione.
In questo lavoro di tesi, analizzando i dati della struttura cristallografica del Dominio di Legame all’ amminoacido (LBD) del AtGLR3.3 di Arabidopsis thaliana, abbiamo identificato dei residui amminoacidici coinvolti nel legame del glutammato. Abbiamo dunque introdotto mutazioni puntiformi nella sequenza genomica del AtGLR3.3 per inficiare o abolire la sua abilità di legare il ligando amminoacidico, e con i costrutti ottenuti abbiamo eseguito una complementazione genetica dei mutanti knock out per il gene GLR3.3 (glr3.3-1 e glr3.3-2). Combinando analisi di imaging, genetica, e bioelettronica, dimostriamo che un danno a livello della foglia, come una ferita o una bruciatura, e l’applicazione di uno stress ipoosmotico alla radice, inducono l’aumento sistemico nella concentrazione apoplastica di L-Glutammato che attiva i GLRs attraverso il legame al loro LBD. Inoltre, il nostro lavoro supporta l’evidenza che gli eventi di segnalazione a lunga distanza siano governati da cambiamenti nello stato di turgore della pianta e che i GLRs siano a valle di essi.Throughout their life plants, being sessile organisms, are continuously exposed to environmental challenges that need to be properly perceived and that require appropriate local and systemic responses. Calcium ion (Ca2+) is a key second messenger in all living beings that couples the perception of extracellular stimuli to characteristics intracellular responses. The specificity of the Ca2+-based signalling is achieved through the generation of specific spatial and temporal transient elevations in the cytosolic Ca2+ concentration [Ca2+]cyt, which are referred to as “Ca2+ signatures”. The interplay of Ca2+ signatures with a toolkit of cognate Ca2+-binding proteins that decode these increases allow the plant to implement a series of tailored physiological responses (e.g., gene expression, metabolism, developmental reprogramming) to withstand the stress. In plants, transient increases in the [Ca2+]cyt have been documented to be involved in several physiological processes including root or pollen tube growth and fertilization, abiotic stress responses, plant-microbe interaction. Ca2+ transients with unique magnitude, frequency, shape, and duration are generated by the orchestrated action of Ca2+ influx and efflux systems that include Ca2+ channels, pumps, and exchangers located at different cellular membranes. Given the importance and universality of Ca2+-based signalling, the identification of actors of the molecular machinery that govern the generation of Ca2+ signals is of primary importance. In this context, the study of Ca2+ dynamics in vivo represents a powerful tool.
In the frame of my PhD, I explored the marvellous world of Ca2+ imaging using some of the instruments made available from a vast universe of genetically encoded fluorescent Ca2+ biosensors. I learned and refined techniques to produce high-end images of in vivo Ca2+ dynamics both at the entire organism and single-cell level. The expertise that I acquired allowed me to contribute to different projects, all unified by the common denominator that is the master regulatory role of Ca2+ in many signalling processes. I therefore contributed to the study of: (i) the [Ca2+]cyt responses of root tip cells in response to different amino acids, helping to define the molecular determinants involved in the process (Alfieri et al., 2020); (ii) the characterization of [Ca2+]cyt transients induced by the administration of natural auxins and auxin analogues, and the deciphering of the role of molecular actors involved in the genesis of the auxin-induced [Ca2+]cyt response (Wang, Himschoot, Grenzi et al., 2022); (iii) the development of a novel genetically encoded Ca2+ biosensors to unravel the role of the endoplasmic reticulum in the shaping of the Ca2+ signature in developmental processes, as well as in response to various stimuli (Resentini, Grenzi et al., 2021); (iv) the modulatory effects of chemicals on the spontaneous [Ca2+]cyt oscillations of guard cells that govern the opening and closing of stomata. I also contributed to the preparation of reviews linked to the field of Ca2+ signalling. All the published manuscripts, as well as works in preparation, are attached at the end of this dissertation, to which I kindly redirect the readers. Here, I am presenting the main work of my PhD project which focused on the understanding of how local damages can trigger inducible defence mechanisms in systemic organs and tissues.
Systemic responses are mediated by long-distance signalling that requires the activity of Glutamate Receptor-Like channels (GLRs). GLRs are homologs of animal Ionotropic Glutamate Receptors (iGluRs) which are ligand-gated cation channels in the central nervous system. Even though iGluRs are gated through the binding with the L-Glutamate, the mechanism throughout GLRs are activated in planta is poorly understood. As an example, we still do not know if the GLRs binding of amino acids is necessary for their activity.
In this PhD thesis, we took the advantage of the recently obtained crystal structure of the Arabidopsis thaliana AtGLR3.3 Ligand Binding Domain (LBD) to identify residues involved in the amino acid-binding. We, therefore, introduced single point mutations in the genome sequence of the AtGLR3.3 gene to prevent or abolish its amino acid-binding, and with the obtained constructs we complemented the glr3.3 KO. By combining high-end imaging, genetics, and bioelectronics we prove that leaf injury, such as wound and burn, and root-applied hypo-osmotic stress induce the systemic apoplastic increase of L-Glutamate that activates GLR channels through their LBD. In addition, our work supports the evidence that long-distance signalling is governed by a systemic change in the turgor state and that GLRs are downstream of it
Noninvasive In Planta Live Measurements of H2O2 and Glutathione Redox Potential with Fluorescent roGFPs-Based Sensors
Get PDFIn this protocol, we present a noninvasive in planta bioimaging technique for the analysis of hydrogen peroxide (H2O2) and glutathione redox potential in adult Arabidopsis thaliana plants. The technique is based on the use of stereo fluorescence microscopy to image A. thaliana plants expressing the two genetically encoded fluorescent sensors roGFP2-Orp1 and Grx1-roGFP2. We provide a detailed step-by-step protocol for performing low magnification imaging with mature plants grown in soil or hydroponic systems. This protocol aims to serve the scientific community by providing an accessible approach to noninvasive in planta bioimaging and data 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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