La forme ou l'arithmetique du temps

This book is designed as the experimental support which makes it possible to the reader to constitute his own imaginary representation of the contents of this writing. The reader thus has to analyze his immediate practice in order to reconstitute the logical process writing-reading-rewriting. This practical reconstitution makes it possible to support the thesis according to which the development of the essential human representations of space and time is consubstantial with the historical development of the human writing-reading-rewriting sequence. The emergence of the writing - graphics in the broad sense - like first representation of the human actions undoubtedly induced temporality even between the action and its graphic act. The spoken language – reading with the phonological signification - gives the symbolic meaning of two successive writing-rewriting acts. The temporal representations of the world thus result chronologically from space emergences of immediate reality thus forming the space-time unit of this world or universe. Some logical, epistemological and philosophical consequences of these theses are approached.Ce livre est conçu comme le support expérimental qui permet au lecteur de constituer sa propre représentation imaginaire du contenu de cet écrit. Le lecteur est ainsi appelé à analyser sa pratique immédiate afin de reconstituer le processus logique écrit-lu-récrit. Cette reconstitution pratique permet de soutenir la thèse selon laquelle le développement des représentations humaines essentielles d'espace et de temps est consubstantiel au développement historique de la suite écriture-lecture-réécriture humaine. L'émergence de l'écriture - graphie au sens large- comme première représentation des actions humaines induit indubitablement la temporalité entre l'action même et son acte graphique. Le langage parlé – lecture au sens phonologique - donne le sens symbolique de deux actes écrit-récrits successifs. Les représentations temporelles du monde résultent donc chronologiquement des émergences spatiales de la réalité immédiate formant ainsi l'unité spatio-temporelle de ce monde ou univers. Quelques conséquences logiques, épistémologiques et philosophiques de ces thèses sont abordées

La forme ou l'arithmetique du temps

This book is designed as the experimental support which makes it possible to the reader to constitute his own imaginary representation of the contents of this writing. The reader thus has to analyze his immediate practice in order to reconstitute the logical process writing-reading-rewriting. This practical reconstitution makes it possible to support the thesis according to which the development of the essential human representations of space and time is consubstantial with the historical development of the human writing-reading-rewriting sequence. The emergence of the writing - graphics in the broad sense - like first representation of the human actions undoubtedly induced temporality even between the action and its graphic act. The spoken language – reading with the phonological signification - gives the symbolic meaning of two successive writing-rewriting acts. The temporal representations of the world thus result chronologically from space emergences of immediate reality thus forming the space-time unit of this world or universe. Some logical, epistemological and philosophical consequences of these theses are approached.Ce livre est conçu comme le support expérimental qui permet au lecteur de constituer sa propre représentation imaginaire du contenu de cet écrit. Le lecteur est ainsi appelé à analyser sa pratique immédiate afin de reconstituer le processus logique écrit-lu-récrit. Cette reconstitution pratique permet de soutenir la thèse selon laquelle le développement des représentations humaines essentielles d'espace et de temps est consubstantiel au développement historique de la suite écriture-lecture-réécriture humaine. L'émergence de l'écriture - graphie au sens large- comme première représentation des actions humaines induit indubitablement la temporalité entre l'action même et son acte graphique. Le langage parlé – lecture au sens phonologique - donne le sens symbolique de deux actes écrit-récrits successifs. Les représentations temporelles du monde résultent donc chronologiquement des émergences spatiales de la réalité immédiate formant ainsi l'unité spatio-temporelle de ce monde ou univers. Quelques conséquences logiques, épistémologiques et philosophiques de ces thèses sont abordées

1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding

Improved synthetic conditions allow preparation of TMSCCl3 in good yield (70 %) and excellent purity. Compounds of the type NBu4X [X=Ph3SiF2 (TBAT), F (tetrabutylammonium fluoride, TBAF), OAc, Cl and Br] act as catalytic promoters for 1,4-additions to a range of cyclic and acyclic nitroalkenes, in THF at 0–25 °C, typically in moderate to excellent yields (37–95 %). TBAT is the most effective promoter and bromide the least effective. Multinuclear NMR studies (1H, 19F, 13C and 29Si) under anaerobic conditions indicate that addition of TMSCCl3 to TBAT (both 0.13 M) at −20 °C, in the absence of nitroalkene, leads immediately to mixtures of Me3SiF, Ph3SiF and NBu4CCl3. The latter is stable to at least 0 °C and does not add nitroalkene from −20 to 0 °C, even after extended periods. Nitroalkene, in the presence of TMSCCl3 (both 0.13 M at −20 °C), when treated with TBAT, leads to immediate formation of the 1,4-addition product, suggesting the reaction proceeds via a transient [Me3Si(alkene)CCl3] species, in which (alkene) indicates an Si⋅⋅⋅O coordinated nitroalkene. The anaerobic catalytic chain is propagated through the kinetic nitronate anion resulting from 1,4 CCl3− addition to the nitroalkene. This is demonstrated by the fact that isolated NBu4[CH2[DOUBLE BOND]NO2] is an efficient promoter. Use of H2C[DOUBLE BOND]CH(CH2)2CH[DOUBLE BOND]CHNO2 in air affords radical-derived bicyclic products arising from aerobic oxidation

"L'espace de la rumeur, pratique d'écoute": étude de l'environnement sonore dans son rapport avec l'architecture, l'urbanisme et le paysage

Rapport d'activités du Laboratoire d'acoustique et musique urbaine de l'Ecole d'architecture de Paris-La Villette. Il est fait le bilan des activités sur le site du barrage à Pierrefitte où sont proposées des solutions d'aménagement qui permettent une maîtrise des nuisances sonores. La seconde partie du rapport fait le point des recherches sur la conception esthétique de l'environnement dans sa qualification sonor

Persilylated phosphoranyl radicals : the first persistent non-cyclic phosphoranyl radicals.

International audienc

Large phosphorus hyperfine coupling as a sensitive tool for studying molecular dynamics : ESR and Molecular Mechanics studies of ring interconversion in cis-2,5-diphosphoryl-2,5-dimethyl-pyrrolidinoxyl radical

ESR spectra of cis- and trans-â-diphosphorylated pyrrolidine-N-oxyl radicals, c-1 and t-1, were studied in liquid and frozen solution. The expected 1:2:1 triplet (aP (2)) of the 1:1:1 triplet (aN) was observed for t-1; however, for c-1, the inner lines of the 1:2:1 triplet showed a dramatic broadening characteristic of chemical exchange between two equivalent conformations. Owing to the large difference in the hyperfine splitting constants (hfsc) of the exchanging phosphorus (¢aP 21 G), the coalescence temperature was unusually high (193 K, in n-pentane), and the potential barrier for ring interconversion (10.5 kJ mol-1) was easily obtained from the temperature dependence of the exchange rate. This value was in very good agreement with the value obtained for an empirical pseudorotational potential (11 kJ mol-1) that was adjusted to fit the temperature dependence of the phosphorus hfsc. For c-1, molecular mechanics calculations gave similar characteristics for the pseudorotational potential and indicated the existence of two identical minima with distorted geometries lying between 3T4 and 3E or 4T3 and E3. For t-1, only the 3T4 conformer was found to be significantly populated. Frozen solution spectra showed that the phosphorus hfsc anisotropy is higher when the C-P bond is pseudoaxial; this result can be explained by a geometry-dependent delocalization of the unpaired electron into the phosphorus 3p orbitals