1,721,026 research outputs found
Expérimentations sur l’utilisation d’un logiciel de modélisation par petits groupes d’élèves
No full textThis article presents results from the use of ModelsCreator by groups of students in problem solving activities through scientific modeling. In this learning environment pupils can create models, think on their behavior and possibly on their limits of validity. This open environment allows pupils to work on entities (represented by objects) and on theirs properties (represented by concepts) that are associated by relationships of qualitative, semi-quantitative (qualitative mathematical formula expression) or quantitative order.Dans cet article nous présentons quelques résultats concernant l’utilisation du logiciel ModelsCreator, dans un cadre de résolution des problèmes, par de petits groupes d’élèves du collège dans des activités de modélisation scientifique. Il s 'agit d 'un logiciel d’apprentissage destiné à permettre aux élèves de créer des modèles, réfléchir sur leur comportement et éventuellement sur leurs limites de validité. ModelsCreator est un environnement ouvert permettant de travailler sur des entités (représentant des objets ) et sur leurs propriétés (représentant des concepts) qui se lient par des relations d’ordre qualitatif semi-quantitatif (expression qualitative des formules mathématiques) ou quantitatif.Komis Vassilis, Dimitracopoulou Angélique, Politis Panagiotis, Avouris Nikolaos. Expérimentations sur l’utilisation d’un logiciel de modélisation par petits groupes d’élèves. In: Sciences et techniques éducatives, volume 8 n°1-2, 2001. Environnements interactifs d'apprentissage avec ordinateur. EIAO'2001, sous la direction de Cyrille Desmoulins, Monique Granbastien et Jean-Marc Labat. pp. 75-86
The role of the nuclear receptor LRH1/NR5A2 in precursor oligodendrocytes
No full textΒιβλιογραφία: σ. 31-33Τα νευρικά κύτταρα αποτελούν τις δομικές μονάδες όλου του νευρικού συστήματος και κατατάσσονται σε κατηγορίες, ανάλογα με την μορφολογία και την λειτουργία τους. Τα ολιγοδενδροκύτταρα, αποτελούν μία κατηγορία αυτών, εντοπίζονται στο κεντρικό νευρικό σύστημα και είναι υπεύθυνα για την παραγωγή μυελίνης, η οποία αποτελεί το μονωτικό έλυτρο που καλύπτει τους περισσότερους νευράξονες. Ανήκουν στα τελικά προϊόντα διαφοροποίησης μιας κυτταρικής γενεαλογίας και για αυτό τον λόγο, διαδικασίες όπως ο πολλαπλασιασμός, η διαφοροποίηση και η μυελινοποίηση, υπόκεινται σε περίπλοκο και ακριβή χρονικά έλεγχο. Η κυτταρική σειρά OLN-93, καθώς παρουσιάζει παρόμοιες ιδιότητες με αυτές των πρόδρομων ολιγοδενδροκυττάρων, θεωρείται ένα χρήσιμο πειραματικό σύστημα για την μελέτη της ρύθμισης του πολλαπλασιασμού και της διαφοροποίησης τους. Επίσης, χρησιμοποιείται και για την μελέτη της επίδρασης του οξειδωτικό στρες (H 2 O 2), το οποίο εμφανίζεται σε αρκετές νευροεκφυλιστικές ασθένειες, και οδηγεί τα ολιγοδενδροκύτταρα σε θανάτωση μέσω απόπτωσης. Ο αντιοξειδωτικός παράγοντας LRH1 (Liver Receptor Homolog-1, NR5A2), είναι ένας ορφανός πυρηνικός υποδοχέας, του οποίου η υπερέκφραση προστατεύει τους νευρώνες από το οξειδωτικό στρες και επάγει την διαφοροποίηση τους σε ώριμα κύτταρα, αλλά είναι ακόμα άγνωστο, αν διαδραματίζει τον ίδιο ρόλο στα ολιγοδενδροκύτταρα. Για την συγκεκριμένη μελέτη, μέσω διάφορων μοριακών τεχνικών, αρχικά πραγματοποιήθηκε έλεγχος της παρουσίας του πυρηνικού υποδοχέα NR5A2 στα πρώιμα ολιγοδενδροκύτταρα και στην συνέχεια υπερέκφραση του στην κυτταρική σειρά OLN-93, προκειμένου να παρατηρηθεί αν τα κύτταρα, οδηγούνται σε διαφοροποίηση και πλήρη ωρίμανση, αλλά και αν προστατεύονται από το οξειδωτικό στρες, μειώνοντας τα επίπεδα θανάτωσης τους, μέσω απόπτωσης. Τα αποτελέσματα των πειραμάτων υποδεικνύουν, πως η υπερέκφραση του πυρηνικού υποδοχέα NR5A2 αυξάνει την αντοχή των ολιγοδενδροκυττάρων παρουσία οξειδωτικού στρες, μειώνοντας τα επίπεδα απόπτωσης, όμως δεν είναι ακόμα βέβαιο, αν ωθεί τα πρώιμα ολιγοδενδροκύτταρα στην πλήρη διαφοροποίηση και ωρίμανση τους κάτω από αυτές τις συνθήκες.Nerve cells constitute the structural units of the entire nervous system and are classified into categories based on their morphology and function. Oligodendrocytes, which are a category of these cells, are found in the central nervous system and are responsible for producing myelin, which forms the insulating sheath that covers most axons. They belong to the final products of a cellular lineage's differentiation, and for this reason, processes such as proliferation, differentiation, and myelination are subject to complex and precise temporal control. The OLN93 cell line, which exhibits properties similar to those of oligodendrocyte progenitors, is considered a useful experimental system for studying the regulation of their proliferation and
differentiation. It is also used to study the effects of oxidative stress (H 2 O 2), which occurs in many neurodegenerative diseases and leads to oligodendrocyte death through apoptosis. The antioxidant factor LRH1 (Liver Receptor Homolog-1, NR5A2) is an orphan nuclear receptor
whose overexpression protects neurons from oxidative stress and induces their differentiation into mature cells. However, it is still unknown whether it plays the same role in oligodendrocytes. In this particular study, through various molecular techniques, the presence of the nuclear receptor NR5A2 in early oligodendrocytes was first assessed, followed by its overexpression in the OLN-93 cell line to observe whether the cells are driven to differentiation and full maturation, and whether they are protected from oxidative stress by reducing their levels of apoptosis. The experimental results suggest that the overexpression of the nuclear receptor NR5A2 increases the resistance of oligodendrocytes to oxidative stress, reducing apoptosis levels. However, it is still uncertain whether it promotes the full differentiation and maturation of early oligodendrocytes, under these conditions.33 σ
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
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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