Absolute frequency measurement of 12C16O2 laser lines with a femtosecond laser comb and new determination of the 12C16O2 molecular constants and frequency grid

Absolute frequency measurements of a CO2 laser stabilized on saturated absorption resonances of CO2 laser lines are reported. They were performed using a femtosecond-laser frequency comb generator and two laser diodes at 852 nm and 782 nm as intermediate oscillators, with their frequency difference phase-locked to the CO2 laser. 20 12C16O2 laser lines in the P and R bands at 9 µm were measured with a relative uncertainty of a few 10-12 limited by the CO2 frequency reproducibility. A new determination of the CO2 molecular constants was obtained from these data and previous measurements in the 10 µm band. The CO2 frequency grid was also calculated, with an improvement of two orders of magnitude compared to the previous grid of Maki et al [A.G. Maki, C.C. Chou, K. Evenson, L.R. Zink and J.T. Shy, J. Mol. Spectrosc. 167, (1994) 211-224]

Le « GR05 ». Approche de quelques revues du xxe siècle

Dans les années 1970, on achetait L’Art vivant et Art press, c’était – avec le tour obligé des galeries le samedi après-midi, le parcours attentif de la Biennale de Paris (Venise était hors de portée) et le cas échéant une virée à la documenta de Kassel – le meilleur moyen d’être dans le coup. Occasionnellement on avait arTitudes sous le bras, plutôt par snobisme (pour ma part, j’avais et j’ai toujours le body art en horreur). Et quand on avait un peu de sous, au hasard d’une visite à la gale..

Correspondance : Gertrude Stein, Pablo Picasso

Tout commence le 9 mars 1906 par un petit mot : Gertrude Stein s’annonce à l’atelier de la rue Ravignan pour l’une des 90 séances de pose que nécessitera son portrait. La dernière missive est un télégramme, du 30 novembre 1944, où elle s’inquiète de ses radiateurs, que le peintre s’était appropriés, nous dit la note en bas de page. On tirera de cet exemple un double constat qui s’impose à la lecture de ce qui est, plutôt qu’une correspondance, un échange épistolaire irrégulier et factuel, au ..

Activation of an ATP-dependent K+ conductance in Xenopus oocytes by expression of adenylate kinase cloned from renal proximal tubules

AbstractIn rabbit proximal convoluted tubules, an ATP-sensitive K+ (KATP) channel has been shown to be involved in membrane cross-talk, i.e. the coupling (most likely mediated through intracellular ATP) between transepithelial Na+ transport and basolateral K+ conductance. This K+ conductance is inhibited by taurine. We sought to isolate this K+ channel by expression cloning in Xenopus oocytes. Injection of renal cortex mRNA into oocytes induced a K+ conductance, largely inhibited by extracellular Ba2+ and intracellular taurine. Using this functional test, we isolated from our proximal tubule cDNA library a unique clone, which induced a large K+ current which was Ba2+-, taurine- and glibenclamide-sensitive. Surprisingly, this clone is not a K+ channel but an adenylate kinase protein (AK3), known to convert NTP+AMP into NDP+ADP (N could be G, I or A). AK3 expression resulted in a large ATP decrease and activation of the whole-cell currents including a previously unknown, endogenous K+ current. To verify whether ATP decrease was responsible for the current activation, we demonstrated that inhibition of glycolysis greatly reduces oocyte ATP levels and increases an inwardly rectifying K+ current. The possible involvement of AK in the KATP channel’s regulation provides a means of explaining their observed activity in cytosolic environments characterized by high ATP concentrations

Structural Determinants of the Closed KCa3.1 Channel Pore in Relation to Channel Gating: Results from a Substituted Cysteine Accessibility Analysis

In this work we address the question of the KCa3.1 channel pore structure in the closed configuration in relation to the contribution of the C-terminal end of the S6 segments to the Ca2+-dependent gating process. Our results based on SCAM (substituted cysteine accessibility method) experiments first demonstrate that the S6 transmembrane segment of the open KCa3.1 channel contains two distinct functional domains delimited by V282 with MTSEA and MTSET binding leading to a total channel inhibition at positions V275, T278, and V282 and to a steep channel activation at positions A283 and A286. The rates of modification by MTSEA (diameter 4.6 Å) of the 275C (central cavity) and 286C residues (S6 C-terminal end) for the closed channel configuration were found to differ by less than sevenfold, whereas experiments performed with the larger MTSET reagent (diameter 5.8 Å) resulted in modification rates 103–104 faster for cysteines at 286 compared with 275. Consistent with these results, the modification rates of the cavity lining 275C residue by MTSEA, Et-Hg+, and Ag+ appeared poorly state dependent, whereas modification rates by MTSET were 103 faster for the open than the closed configuration. A SCAM analysis of the channel inner vestibule in the closed state revealed in addition that cysteine residues at 286 were accessible to MTS reagents as large as MTS-PtrEA, a result supported by the observation that binding of MTSET to cysteines at positions 283 or 286 could neither sterically nor electrostatically block the access of MTSEA to the closed channel cavity (275C). It follows that the closed KCa3.1 structure can hardly be accountable by an inverted teepee-like structure as described for KcsA, but is better represented by a narrow passage centered at V282 (equivalent to V474 in Shaker) connecting the channel central cavity to the cytosolic medium. This passage would not be however restrictive to the diffusion of small reagents such as MTSEA, Et-Hg+, and Ag+, arguing against the C-terminal end of S6 forming an obstructive barrier to the diffusion of K+ ions for the closed channel configuration

Archives et création : nouvelles perspectives sur l’archivistique. Cahier 2

Ce cahier de recherche fait état des travaux menés au cours de la deuxième étape (2014-2015) du projet « Archives et création : nouvelles perspectives sur l’archivistique ». Les textes sont les suivants : Yvon Lemay et Anne Klein, « Préface », p. 4-5; Yvon Lemay, « Deuxième cahier de recherche : présentation », p. 6-26; Érika Nimis, « Combler les silences de l’histoire africaine. Ou comment des artistes visuels s’approprient des archives photographiques pour éclairer le passé à la lumière du présent », p. 27-42; Hélène Brousseau, « L'utilisation d’archives dans les arts visuels : dialogue entre une artiste et une archiviste », p. 43-58; Simon Côté-Lapointe, « Créer à partir d’archives : bilan, démarches et techniques d’un projet exploratoire », p. 59-95; Annaëlle Winand, « Le concept d’archive(s) et les films de réemploi », p. 96-111; Nicolas Bednarz et Céline Widmer, « Archives au pluriel : le Montréal de 1914-1918. L’expérience d’une création collaborative et multidisciplinaire », p. 112-142; Mattia Scarpulla, « La mémoire performative. Considérations sur les traces de la danse et les dispositifs de capture des mouvements », p. 143-173; Yvon Lemay et Anne Klein, « Quartiers disparus : l’envers du décor », p. 174-190. De plus, le cahier comprend une « Bibliographie » des travaux effectués sur les archives et la création depuis 2007, p. 191-196, et des informations sur « Les auteurs », p. 197.Le projet de recherche est financé par le Conseil de recherches en sciences humaines du Canada (Programme Savoir, 2013-2016)

Cysteine Mutagenesis and Computer Modeling of the S6 Region of an Intermediate Conductance IKCa Channel

Cysteine-scanning mutagenesis (SCAM) and computer-based modeling were used to investigate key structural features of the S6 transmembrane segment of the calcium-activated K+ channel of intermediate conductance IKCa. Our SCAM results show that the interaction of [2-(trimethylammonium)ethyl] methanethiosulfonate bromide (MTSET) with cysteines engineered at positions 275, 278, and 282 leads to current inhibition. This effect was state dependent as MTSET appeared less effective at inhibiting IKCa in the closed (zero Ca2+ conditions) than open state configuration. Our results also indicate that the last four residues in S6, from A283 to A286, are entirely exposed to water in open IKCa channels, whereas MTSET can still reach the 283C and 286C residues with IKCa maintained in a closed state configuration. Notably, the internal application of MTSET or sodium (2-sulfonatoethyl) methanethiosulfonate (MTSES) caused a strong Ca2+-dependent stimulation of the A283C, V285C, and A286C currents. However, in contrast to the wild-type IKCa, the MTSET-stimulated A283C and A286C currents appeared to be TEA insensitive, indicating that the MTSET binding at positions 283 and 286 impaired the access of TEA to the channel pore. Three-dimensional structural data were next generated through homology modeling using the KcsA structure as template. In accordance with the SCAM results, the three-dimensional models predict that the V275, T278, and V282 residues should be lining the channel pore. However, the pore dimensions derived for the A283–A286 region cannot account for the MTSET effect on the closed A283C and A286 mutants. Our results suggest that the S6 domain extending from V275 to V282 possesses features corresponding to the inner cavity region of KcsA, and that the COOH terminus end of S6, from A283 to A286, is more flexible than predicted on the basis of the closed KcsA crystallographic structure alone. According to this model, closure by the gate should occur at a point located between the T278 and V282 residues

Archives et création : nouvelles perspectives sur l'archivistique. Cahier 1

Ce cahier de recherche fait état des travaux menés au cours de la première étape (2013-2014) du projet « Archives et création : nouvelles perspectives sur l’archivistique ». Il comprend les textes suivants : Yvon Lemay et Anne Klein, « Introduction », p. 4-6; Yvon Lemay, « Archives et création : nouvelles perspectives sur l’archivistique », p. 7-19; Anne-Marie Lacombe, « Exploitation des archives à des fins de création : un aperçu de la littérature », p. 20-59; Simon Côté-Lapointe, « Archives sonores et création : une pratique à la croisée des chemins », p. 60-83; Hélène Brousseau, « Fibres, archives et société », p. 84-104; Annie Lecompte-Chauvin, « Comment les archives entrent dans nos vies par le biais de la littérature », p. 105-120; Aude Bertrand, « Valeurs, usages et usagers des archives », p. 121-150; Laure Guitard, « Indexation, émotions, archives », p. 151-168; Anne Klein, Denis Lessard et Anne-Marie Lacombe, « Archives et mise en archives dans le champ culturel. Synthèse du colloque « Archives et création, regards croisés : tournant archivistique, courant artistique », p. 169-178. De plus, dans le but de situer le projet dans un contexte plus large, le cahier inclut une bibliographie des travaux effectués sur les archives et la création depuis 2007, p. 179-182.Le projet de recherche est financé par le Conseil de recherches en sciences humaines du Canada (Programme Savoir, 2013-2016)

Understanding the role of contrasting urban contexts in healthy aging: an international cohort study using wearable sensor devices (the CURHA study protocol).

BACKGROUND: Given the challenges of aging populations, calls have been issued for more sustainable urban re-development and implementation of local solutions to address global environmental and healthy aging issues. However, few studies have considered older adults' daily mobility to better understand how local built and social environments may contribute to healthy aging. Meanwhile, wearable sensors and interactive map-based applications offer novel means for gathering information on people's mobility, levels of physical activity, or social network structure. Combining such data with classical questionnaires on well-being, physical activity, perceived environments and qualitative assessment of experience of places opens new opportunities to assess the complex interplay between individuals and environments. In line with current gaps and novel analytical capabilities, this research proposes an international research agenda to collect and analyse detailed data on daily mobility, social networks and health outcomes among older adults using interactive web-based questionnaires and wearable sensors. METHODS/DESIGN: Our study resorts to a battery of innovative data collection methods including use of a novel multisensor device for collection of location and physical activity, interactive map-based questionnaires on regular destinations and social networks, and qualitative assessment of experience of places. This rich data will allow advanced quantitative and qualitative analyses in the aim to disentangle the complex people-environment interactions linking urban local contexts to healthy aging, with a focus on active living, social networks and participation, and well-being. DISCUSSION: This project will generate evidence about what characteristics of urban environments relate to active mobility, social participation, and well-being, three important dimensions of healthy aging. It also sets the basis for an international research agenda on built environment and healthy aging based on a shared and comprehensive data collection protocol