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State of the art low index contrast planar photonic crystals
No full textLOEQSCI-SB-RHinvited communicatio
Evolutionarily Conserved Functional Mechanics across Pepsin-like and Retroviral Aspartic Proteases
No full textThe biol. function of the aspartic protease from HIV-1 has recently been related to the conformational flexibility of its structural scaffold. Here, we use a multistep strategy to investigate whether the same mechanism affects the functionality in the pepsin-like fold. (i) We identify the set of conserved residues by using sequence-alignment techniques. These residues cluster in three distinct regions: near the cleavage-site cavity, in the four b-sheets crosslinking the two lobes, and in a solvent-exposed region below the long b-hairpin in the N-terminal lobe. (ii) We elucidate the role played by the conserved residues for the enzymic functionality of one representative member of the fold family, the human b-secretase, by means of classical mol. dynamics (MD). The conserved regions exhibit little overall mobility and yet are involved into the most important modes of structural fluctuations. These modes influence the substrate-catalytic aspartates distance through a relative rotation of the N- and C-terminal lobes. (iii) We investigate the effects of this modulation by estg. the reaction free energy at different representative substrate/enzyme conformations. The activation free energy is strongly affected by large-scale protein motions, similarly to what has been obsd. in the HIV-1 enzyme. (iv) We extend our findings to all other members of the two eukaryotic and retroviral fold families by recurring to a simple, topol.-based, energy functional. This anal. reveals a sophisticated mechanism of enzymic activity modulation common to all aspartic proteases. We suggest that aspartic proteases have been evolutionarily selected to possess similar functional motions despite the obsd. fold variations. [on SciFinder (R)]LCB
Generalized connection graph method for synchronization in asymmetrical networks
No full textWe present a general framework for studying global complete synchronization in networks of dynamical systems with asymmetrical connections. We extend the connection graph stability method, originally developed for symmetrically coupled networks, to the general asymmetrical case. The principal new component of the method is the transformation of the directed connection graph into an undirected graph. In our method for symmetrically coupled networks we have to choose a path between each pair of nodes. The extension of the method to asymmetrical coupling consists in symmetrizing the graph and associating a weight to each path. This weight involves the “node unbalance” of the two nodes. This quantity is defined to be the difference between the sum of connection coefficients of the outgoing edges and the sum of the connection coefficients of the incoming edges to the node. The synchronization condition for this symmetrized-and-weighted network then also guarantees synchronization in the original asymmetrical network.LANO
Analysis of control-oriented wake modeling tools using lidar field results
No full textThe objective of this paper is to compare field data from a scanning lidar mounted on a turbine to control-oriented wind turbine wake models. The measurements were taken from the turbine nacelle looking downstream at the turbine wake. This field campaign was used to validate control-oriented tools used for wind plant control and optimization. The National Wind Technology Center in Golden, CO, conducted a demonstration of wake steering on a utility-scale turbine. In this campaign, the turbine was operated at various yaw misalignment set points, while a lidar mounted on the nacelle scanned five downstream distances. Primarily, this paper examines measurements taken at 2.35 diameters downstream of the turbine. The lidar measurements were combined with turbine data and measurements of the inflow made by a highly instrumented meteorological mast on-site. This paper presents a quantitative analysis of the lidar data compared to the control-oriented wake models used under different atmospheric conditions and turbine operation. These results show that good agreement is obtained between the lidar data and the models under these different conditions.WIR
Approche climatique de la façade : pour une évaluation multicritères
No full textLa prise en compte de paramètres liés au concept de développement durable confronte la pratique architecturale à une meilleure adéquation avec les principes de l'énergétique du bâtiment. Si les expressions fleurissent pour qualifier ce type d'approche, c'est avant tout la cohérence globale de la démarche qui revêt un enjeu fondamental et permet une appréciation critique. Tout résultat concluant passe ainsi par un processus d'optimisation de multiples paramètres, tant pour les bâtiments à enveloppe simple que pour ceux, plus complexes, à façades double-peau.LAS
Functional characterization of the TERRA transcriptome at damaged telomeres
No full textTelomere deprotection occurs during tumorigenesis and aging upon telomere shortening or loss of the telomeric shelterin component TRF2. Deprotected telomeres undergo changes in chromatin structure and elicit a DNA damage response (DDR) that leads to cellular senescence. The telomeric long noncoding RNA TERRA has been implicated in modulating the structure and processing of deprotected telomeres. Here, we characterize the human TERRA transcriptome at normal and TRF2-depleted telomeres and demonstrate that TERRA upregulation is occurring upon depletion of TRF2 at all transcribed telomeres. TRF2 represses TERRA transcription through its homodimerization domain, which was previously shown to induce chromatin compaction and to prevent the early steps of DDR activation. We show that TERRA associates with SUV39H1 H3K9 histone methyltransferase, which promotes accumulation of H3K9me3 at damaged telomeres and end-to-end fusions. Altogether our data elucidate the TERRA landscape and defines critical roles for this RNA in the telomeric DNA damage response.UPLI
Stimulation by nicotine of enteric inhibitory nerves and release of vasoactive intestinal peptide in the taenia of the guinea-pig caecum
No full textThe stimulation by nicotine of intramural nerves and the role of ATP and vasoactive intestinal peptide (VIP) as inhibitory transmitters were studied in the isolated taenia of the guinea-pig caecum. Nicotine (4-32 microM) caused transient, concentration-dependent relaxations which were unaffected by atropine, prazosin or sotalol. Drugs with membrane-stabilizing activity, such as dl-propranolol (0.5 microM), d-propranolol (0.5 microM) or lidocaine (10 microM) antagonized the nicotine-induced relaxation without modifying the response to electrical field stimulation. Similar results were obtained with the cyclooxygenase inhibitor, indomethacin (2.8 microM). Nucleotide pyrophosphatase (0.5 U/ml), which hydrolyzes ATP to AMP, reversibly inhibited the response to nicotine but the response to field stimulation was not decreased. Nicotine evoked a calcium-dependent release of VIP, which was blocked by tetrodotoxin (1 microM), d-propranolol (0.5 microM) or, as previously shown, by apamin (0.2 microM). The finding that nicotine-induced relaxation was accompanied by the neuronal release of VIP is compatible with the possibility that VIP is an inhibitory transmitter but is not definitive evidence, since it could have been due to the stimulation of distinct populations of nerves by nicotine.LND