984 research outputs found
Analysis of Mathieu Equation Stable Solutions in the First Zone of Stability
No full textAbstractThe paper presents the results of a homogeneous Mathieu equation studies. Mathieu equation solutions are oscillations, modulated in amplitude and frequency. In the computational experiments we found dependences of the given oscillations on the ratio of the coefficients. These dependences are shown in graphs that can be used for an approximate estimation of the Mathieu equation solutions without integration
Epigenetics controls of the cell cycle : functions and regulation of the lysine methyltransferase PR-Set7
No full textLa lysine méthyltransférase PR-Set7 est responsable de la monométhylation de la lysine 20 de l'histone H4 (H4K20me1). Son expression varie au cours du cycle cellulaire. D'un niveau peu élevé en phase S, l'enzyme atteint un niveau maximum au cours de la mitose. Mon projet de thèse avait pour but de caractériser les fonctions de PR-Set7 et les raisons de cette régulation au cours du cycle. Présentés sous forme de publication, les résultats de ma thèse montrent que PR-Set7 induit un signal H4K20me1 au niveau des origines de réplication pendant la mitose, ce qui permet le recrutement des complexes de pré-réplication (Pre-RC) contenant les facteurs nécessaires à la formation des fourches de réplication lors la phase S suivante. En effet, la présence de PR-Set7 sur une séquence d'ADN spécifique est suffisante pour induire le co-recrutement des protéines du complexe Pre-RC, tandis que l'inactivation de l'enzyme conduit au contraire à un défaut d'assemblage de ces complexes suivi d'un stress réplicatif. Lors de la phase S, PR-Set7 est dégradée par le complexe Cul4-DDB1, via son interaction avec la protéine PCNA. Cette dégradation permet la disparition du signal H4K20me1 des origines et l'inhibition des complexes Pre-RC, s'assurant ainsi que les origines sont actives une seule fois par cycle cellulaire. La mutation du domaine d'interaction avec PCNA est suffisante pour empêcher la dégradation de PR-Set7, entraînant alors la maintenance du signal H4K20me1 et une activation répétée des origines pendant la phase S (phénotype de sur-réplication). L'ensemble de mes résultats établissent PR-Set7 et le signal H4-K20me1 comme un nouveau mécanisme épigénétique de contrôle des origines de réplication chez les mammifères.The lysine methyltransferase PR-Set7 is responsible of the monomethylation of lysine 20 of histone H4 (H4K20me1). Its expression is cell-cycle regulated. With weak levels in S phase, this enzyme reach a peak level during mitosis. My PhD project was to characterize the functions of PR-Set7 and the reasons underlying its cell-cycle regulation. Presented as publications, my results show that PR-Set7 induces H4K20me1 on replication origins during mitosis, which allows recruitment of pre-replication complexes (Pre-RC) containing all the factors required to create replication forks during the next S phase. Indeed, the presence of PR-Set7 on a specific DNA sequence is sufficient to induce the co-recruitment of Pre-RC complex proteins, whereas the inactivation of this enzyme leads to defects in the assembly of these complexes followed by a replicative stress. During S phase, PR-Set7 is degraded par the Cul4-DDB1 complex through its association with PCN A. This degradation induces the disappearance of H4K20me1 on origins and inhibition of Pre-RC complexes, ensuring that origins are activated only once per cell cycle. Mutations in the interaction domain with PCNA are sufficient to prevent PR-Set7 degradation, leading to the maintenance of H4K20me1 and a multiple activation of origins during S phase (over-replication phenotype). My results establish PR-Set7 and H4K20me1 as a new epigenetic mechanism to control replication origins in mammals
Pensar las escalas para pensar las luchas: Autor: Mathieu UHEL
No full textA través de un título sugerente, “pensar las escalas para pensar las luchas”, Mathieu Uhel entreteje la construcción teórico-crítica del concepto escala, generada por la geografía radical anglosajona de finales del siglo XX, con la necesidad/utilidad práctica de la escala para concienciar las luchas sociales. El artículo cumple un doble propósito: por un lado, delinear los elementos de lectura sobre el concepto escala; y, con ello, promover la atención de esta problemática en las luchas contemporáneas. En un primer apartado, Uhel ubica las discusiones académicas en torno a la escala, como herramienta metodológica útil para comprender la complejidad de las sociedades capitalistas; en el segundo apartado, el autor avanza la exposición en torno al contexto de la dimensión escalar del imperialismo capitalista; finalmente, el autor se centra en el rol de la actividad política a escala nacional en la tensa relación entre las imposiciones del capital y la lucha social.Por meio de um título sugestivo, “pensando escalas para pensar lutas”, Mathieu Uhel entrelaça a construção teórico-crítica do conceito de escala, gerado pela geografia radical anglo-saxônica do final do século XX, com a necessidade / utilidade prática escala para aumentar a consciência das lutas sociais. O artigo tem um duplo propósito: por um lado, delinear os elementos de leitura sobre o conceito de escala; e, com isso, promover atenção a esse problema nas lutas contemporâneas. Na primeira seção, Uhel localiza as discussões acadêmicas em torno da escala, como uma ferramenta metodológica útil para compreender a complexidade das sociedades capitalistas; na segunda seção, o autor avança a exposição em torno do contexto da dimensão escalar do imperialismo capitalista; por fim, o autor enfoca o papel da atividade política em escala nacional na tensa relação entre as imposições do capital e a luta social.Mathieu Uhel\u27s suggestive title, “Thinking about scales to think about struggles”, he interweaves the theoretical-critical construction of concept scale, generated by radical Anglo-Saxon geography in the late 20th century, with it´s practical utility to social struggles. The article serves two purposes: on the one hand, Uhel locates academic discussion around scale; and, with this, he promotes attention to this problem in contemporary struggles. In the first section, Uhel locates academic discussions around scale, as a useful methodological tool to understand the complexity of capitalist societies; in the second section, the author advances the argument around the context of the scalar dimension of capitalist imperialism; finally, the author focuses on the role of political activity on a national scale in the tense relationship between the impositions of capital and the social movement
Mathieu Ichou, Les Enfants d’immigrés à l’école
No full textIt is common to hear in the fields of educational and immigration sociology that on average, the children of immigrants do not perform as well in school as children of native-born parents. Mathieu Ichou offers an innovative sociological analysis on a topic that is heavily exploited by political and media discourse, and subject to much scientific controversy. The author takes distance from the homogenized vision of a “second generation” of students who have totally failed academically, and rep..
Telomere chromatin establishment and its maintenance during mammalian development
No full textInternational audienceTelomeres are specialized structures that evolved to protect the end of linear chromosomes from the action of the cell DNA damage machinery. They are composed of tandem arrays of repeated DNA sequences with a specific heterochromatic organization. The length of telomeric repeats is dynamically regulated and can be affected by changes in the telomere chromatin structure. When telomeres are not properly controlled, the resulting chromosomal alterations can induce genomic instability and ultimately the development of human diseases, such as cancer. Therefore, proper establishment, regulation, and maintenance of the telomere chromatin structure are required for cell homeostasis. Here, we review the current knowledge on telomeric chromatin dynamics during cell division and early development in mammals, and how its proper regulation safeguards genome stability
L'impatto dell'attività tintoria sull'ambiente. Firenze alla fine del Medioevo
No full textThe author aims to examine and categorize the range of dyeings materials used in the Florentine wool and silk textile industries in the late Middle Ages, focusing mainly on those produced within the regional space in order to evaluate the impact of the Florentine dyeing activity on the natural environment and the productive landscape of the Tuscan countryside. In particular, the author establishes a line of demarcation between cultivated and uncultivated resources in order to verify which constitutes an indication of the level of industrial development of medieval textile production. This further focuses on how the transition from the exploitation of wild resources to the exploitation of cultivated resources could reflect a greater degree of economic integration between the countryside and the city and contribute to the formation of a regional economic space
Mathieu de Fossey: su visión del mundo indígena mexicano
No full textThroughout these pages the author shows how Mathieu de Fossey perceived that it was not easy to make indigenous communities fit within the mould of the nation-state which, being based on the liberal and egualitarian ideology, was against the recognition of special regimes, such as those that created a peculiar status for the native population of the American territory during the period of Spanish colonial domination
Mathieu de Fossey: su visión del mundo indígena mexicano
No full textÀ travers ces pages, l’auteur montre comment Mathieu de Fossey avait perçu la difficulté d’insérer le monde des communautés indigènes dans le moule d’un État national qui, accroché à une idéologie libérale égalitaire, refusait d’établir des régimes spéciaux comparables à ceux qui, durant la domination espagnole, avaient reconnu un statut particulier aux populations natives du continent américain.A través de estas páginas se muestra cómo Mathieu de Fossey percibió el difícil acoplamiento del mundo de las comunidades indígenas en el molde de un Estado nacional que, por estar sustentado en la ideología liberal igualitaria, era contrario al reconocimiento de regímenes especiales como los que, durante la dominación española, habían establecido un status peculiar para los aborígenes del territorio americano.Throughout these pages the author shows how Mathieu de Fossey perceived that it was not easy to make indigenous communities fit within the mould of the nation-state which, being based on the liberal and egualitarian ideology, was against the recognition of special regimes, such as those that created a peculiar status for the native population of the American territory during the period of Spanish colonial domination
Investigation of documents persistency on the Web
No full text@inproceedings{CI-Lancieri-2004-2, author = {Lancieri, Luigi and Lecouvey, Mathieu and Glasse, Veronique}, title = {Investigation of documents persistency on the Web}, booktitle = {International conference E-Society 2004 (ES2004), IADIS}, year = {2004}, address = {Spain} }International audienc
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