Les dessins de machines à l’Ecole polytechnique (1794-1850), iconographie commentée

Cet ensemble de reproductions - planches imprimées et dessins d’élèves - choisies dans les Archives conservées à la Bibliothèque centrale, permet de se faire une idée de ce que fut le « cours de Machines » de l’Ecole polytechnique entre 1794 et 1850. La mise en place d’un cours autonome n’aboutit qu’en 1806, dans le cadre de la Géométrie. Il rejoint les Applications de l’Analyse après 1817, et devient « cours de Machines et d’Hydraulique » en 1839. Pour finir, cet enseignement sera rattaché à..

Deuxième partie - Le cours de Hachette : 1806 - 1816

La loi d’organisation de l’Ecole prescrit un cours d’application de la géométrie descriptive aux éléments des machines. Mais on lit dans le procès-verbal de la séance du Conseil d’instruction du 25 juin 1800 que « vu l’absence du citoyenMonge, qui s’était chargé de faire un cours sur les Eléments des Machines, le Conseil arrête que ce Cours n’aura pas lieu cette année (...) ». Un nouveau projet est élaboré pour l’année suivante ; Monge repart en Italie et le cours de Machines est encore ajou..

Première partie – La genèse d’un enseignement : 1794 - 1806

Avec la Révolution française s’ouvre un débat sur l’enseignement scientifique et technique. Les projets sont nombreux et concernent tous les niveaux. Mais le fait le plus marquant de cette période est sans doute la fondation en 1794 de l’Ecole centrale des travaux publics, destinée à remplacer les deux écoles d’ingénieurs créées au milieu du XVIIIe siècle : celle des Ponts et Chaussées (à Paris) et celle du Génie (à Mézières). L’Ecole est rebaptisée Ecole polytechnique dès 1795 et sa mise en ..

Le cours de Machines de l’Ecole polytechnique, de sa création jusqu’en 1850

La création de l’Ecole centrale des travaux publics et les débuts de l’Ecole polytechnique sont relativement bien connus. Le « cours de Machines » l’est beaucoup moins ; il n’a pas encore été étudié pour lui-même, bien qu’il présente un intérêt certain : cet enseignement est le premier du genre. La consultation des Archives de l’Ecole permet d’en suivre la mise en œuvre, dans le détail de son déroulement, et de corriger l’impression de confusion, voire les contradictions qui ressortent de cer..

Troisième partie - Les Machines, cours d’application : 1817 – 1850

La Restauration et la remise en ordre de l’enseignement de l’Ecole La chute de l’Empire et la Restauration de la monarchie s’accompagnent d’un certain nombre de changements à l’Ecole polytechnique. A la suite de manifestations des élèves, ceux-ci sont licenciés le 14 avril 1816. L’Ecole est rouverte le 17 janvier 1817 et le Conseil de perfectionnement, maintenant constitué de personnalités extérieures et présidé par un Pair de France, réorganise l’enseignement. Le nouveau régime sanctionne au..

Computational identification of transcriptionally co-regulated genes, validation with the four ANT isoform genes.

International audienceABSTRACT: BACKGROUND: The analysis of gene promoters is essential to understand the mechanisms of transcriptional regulation required under the effects of physiological processes, nutritional intake or pathologies. In higher eukaryotes, transcriptional regulation implies the recruitment of a set of regulatory proteins that bind on combinations of nucleotide motifs. We developed a computational analysis of promoter nucleotide sequences, to identify co-regulated genes by combining several programs that allowed us to build regulatory models and perform a crossed analysis on several databases. This strategy was tested on a set of four human genes encoding isoforms 1 to 4 of the mitochondrial ADP/ATP carrier ANT. Each isoform has a specific tissue expression profile linked to its role in cellular bioenergetics. RESULTS: From their promoter sequence and from the phylogenetic evolution of these ANT genes in mammals, we constructed combinations of specific regulatory elements. These models were screened using the full human genome and databases of promoter sequences from human and several other mammalian species. For each of transcriptionally regulated ANT1, 2 and 4 genes, a set of co-regulated genes was identified and their over-expression was verified in microarray databases. CONCLUSIONS: Most of the identified genes encode proteins with a cellular function and specificity in agreement with those of the corresponding ANT isoform. Our in silico study shows that the tissue specific gene expression is mainly driven by promoter regulatory sequences located up to about a thousand base pairs upstream the transcription start site. Moreover, this computational strategy on the study of regulatory pathways should provide, along with transcriptomics and metabolomics, data to construct cellular metabolic networks

Chronique d’une invention : le phonautographe d’Édouard-Léon Scott de Martinville (1817-1879) et les cercles parisiens de la science et de la technique

Cette étude, entreprise par la Commission d’histoire de la Société d’encouragement après la visite récente de chercheurs américains à la poursuite des grands ancêtres de l’enregistrement sonore, nous a conduits sur les traces d’un « artiste » peu connu aujourd’hui, Édouard-Léon Scott de Martinville [1817-1879]. L’activité de cet inventeur, précurseur des études modernes de phonétique acoustique, témoigne du fonctionnement des milieux académiques et industriels du Second Empire, à la charnière de la science et de la technique. Et ses apports se sont avérés aller bien au-delà de ce qu’il avait pu lui-même imaginer.Following a recent visit of two American scholars in Paris, looking for the great ancestors of the sound recordings, some members of the Historical Commission of the « Société d’encouragement pour l’industrie nationale » undertook a study on Edouard-Léon Scott de Martinville (1817-1879) and his activities. This inventor, who is not very well-known today, is one of the precursors of modern studies on acoustical phonetics. Scott’s activities illustrate the part played by academic and industrial circles during the French Second Empire for connecting between science and technology. Surprisingly, Scott’s contributions went beyond those he himself imagined

Elevation and cholera: an epidemiological spatial analysis of the cholera epidemic in Harare, Zimbabwe, 2008-2009

BACKGROUND: In highly populated African urban areas where access to clean water is a challenge, water source contamination is one of the most cited risk factors in a cholera epidemic. During the rainy season, where there is either no sewage disposal or working sewer system, runoff of rains follows the slopes and gets into the lower parts of towns where shallow wells could easily become contaminated by excretes. In cholera endemic areas, spatial information about topographical elevation could help to guide preventive interventions. This study aims to analyze the association between topographic elevation and the distribution of cholera cases in Harare during the cholera epidemic in 2008 and 2009. METHODS: We developed an ecological study using secondary data. First, we described attack rates by suburb and then calculated rate ratios using whole Harare as reference. We illustrated the average elevation and cholera cases by suburbs using geographical information. Finally, we estimated a generalized linear mixed model (under the assumption of a Poisson distribution) with an Empirical Bayesian approach to model the relation between the risk of cholera and the elevation in meters in Harare. We used a random intercept to allow for spatial correlation of neighboring suburbs. RESULTS: This study identifies a spatial pattern of the distribution of cholera cases in the Harare epidemic, characterized by a lower cholera risk in the highest elevation suburbs of Harare. The generalized linear mixed model showed that for each 100 meters of increase in the topographical elevation, the cholera risk was 30% lower with a rate ratio of 0.70 (95% confidence interval=0.66-0.76). Sensitivity analysis confirmed the risk reduction with an overall estimate of the rate ratio between 20% and 40%. CONCLUSION: This study highlights the importance of considering topographical elevation as a geographical and environmental risk factor in order to plan cholera preventive activities linked with water and sanitation in endemic areas. Furthermore, elevation information, among other risk factors, could help to spatially orientate cholera control interventions during an epidemic

Pathogenic variants in THSD4, encoding the ADAMTS-like 6 protein, predispose to inherited thoracic aortic aneurysm

Purpose Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening disease with often unrecognized inherited forms. We sought to identify novel pathogenic variants associated with autosomal dominant inheritance of TAAD. Methods We analyzed exome sequencing data from 35 French TAAD families and performed next-generation sequencing capture panel of genes in 1114 unrelated TAAD patients. Functional effects of pathogenic variants identified were validated in cell, tissue, and mouse models. Results We identified five functional variants inTHSD4of which two heterozygous variants lead to a premature termination codon.THSD4encodes ADAMTSL6 (member of the ADAMTS/L superfamily), a microfibril-associated protein that promotes fibrillin-1 matrix assembly. TheTHSD4variants studied lead to haploinsufficiency or impaired assembly of fibrillin-1 microfibrils.Thsd4(+/-)mice showed progressive dilation of the thoracic aorta. Histologic examination of aortic samples from a patient carrying aTHSD4variant and fromThsd4(+/-)mice, revealed typical medial degeneration and diffuse disruption of extracellular matrix. Conclusion These findings highlight the role of ADAMTSL6 in aortic physiology and TAAD pathogenesis. They will improve TAAD management and help develop new targeted therapies

A palaeoecological model for the late Mesoproterozoic – early Neoproterozoic Atar/El Mreïti Group, Taoudeni Basin, Mauritania, northwestern Africa

Reconstructing the spatial distribution of early eukaryotes in palaeoenvironments through Proterozoic sedimentary basins provides important information about their palaeocology and taphonomic conditions. Here, we combine the geological context and a reconstruction of palaeoenvironmental redox conditions (using iron speciation) with quantitative analysis of microfossil assemblages (eukaryotes and incertae sedis), to provide the first palaeoecological model for the Atar/El Mreïti Group of the Taoudeni Basin. Our model suggests that in the late Mesoproterozoic – early Neoproterozoic, the availability of both molecular oxygen and nutrients controlled eukaryotic diversity, higher in oxic shallow marginal marine environments, while coccoidal colonies and benthic microbial mats dominated respectively in anoxic iron-rich and euxinic waters during marine highstands or away from shore where eukaryotes are lower or absent