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Selected AbstractsPost-earthquake bridge repair cost and repair time estimation methodologyEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2010Kevin R. Mackie Abstract While structural engineers have traditionally focused on individual components (bridges, for example) of transportation networks for design, retrofit, and analysis, it has become increasingly apparent that the economic costs to society after extreme earthquake events are caused at least as much from indirect costs as direct costs due to individual structures. This paper describes an improved methodology for developing probabilistic estimates of repair costs and repair times that can be used for evaluating the performance of new bridge design options and existing bridges in preparation for the next major earthquake. The proposed approach in this paper is an improvement on previous bridge loss modeling studies,it is based on the local linearization of the dependence between repair quantities and damage states so that the resulting model follows a linear relationship between damage states and repair points. The methodology uses the concept of performance groups (PGs) that account for damage and repair of individual bridge components and subassemblies. The method is validated using two simple examples that compare the proposed method to simulation and previous methods based on loss models using a power,law relationship between repair quantities and damage. In addition, an illustration of the method is provided for a complete study on the performance of a common five-span overpass bridge structure in California. Intensity-dependent repair cost ratios (RCRs) and repair times are calculated using the proposed approach, as well as plots that show the disaggregation of repair cost by repair quantity and by PG. This provides the decision maker with a higher fidelity of data when evaluating the contribution of different bridge components to the performance of the bridge system, where performance is evaluated in terms of repair costs and repair times rather than traditional engineering quantities such as displacements and stresses. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fragmentation patterns of new esterified and unesterified aromatic 1-hydroxymethylene-1, 1-bisphosphonic acids by ESI-MSnJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2008Julie Hardouin Abstract 1-Hydroxymethylene-1,1-bisphosphonic acids (HMBPs) are compounds that have interesting pharmacological applications. Unfortunately few studies exist on their analyses by mass spectrometry (MS). In this work, we have analyzed new aromatic HMBPs and their prodrugs with electrospray tandem mass spectrometry (ESI-MSn). We describe, for the first time, a complete study of fragmentation patterns, in both positive and negative-ion modes. In positive mode, the cation dissociations are mainly elimination of water and phosphorus fragments. In negative mode, losses of ROH (RH, C6H5, CH3OC6H5) and HPO2 were observed. The results have revealed specific structural fingerprints for the screening of these compounds in complex biological mixtures. Copyright © 2008 John Wiley & Sons, Ltd. [source] A personal account of the role of peptide research in drug discovery: the case of hepatitis C,JOURNAL OF PEPTIDE SCIENCE, Issue 1 2001Antonello Pessi Abstract Although peptides themselves are not usually the end products of a drug discovery effort, peptide research often plays a key role in many aspects of this process. This will be illustrated by reviewing the experience of peptide research carried out at IRBM in the course of our study of hepatitis C virus (HCV). The target of our work is the NS3/4A protease, which is essential for maturation of the viral polyprotein. After a thorough examination of its substrate specificity we fine-tuned several substrate-derived peptides for enzymology studies, high-throughput screening and as fluorescent probes for secondary binding assays. In the course of these studies we made the key observation: that the protease is inhibited by its own cleavage products. Single analog and combinatorial optimization then derived potent peptide inhibitors. The crucial role of the NS4A cofactor was also addressed. NS4A is a small transmembrane protein, whose central domain is the minimal region sufficient for enzyme activation. Structural studies were performed with a peptide corresponding to the minimal activation domain, with a series of product inhibitors and with both. We found that NS3/4A is an induced fit enzyme, requiring both the cofactor and the substrate to acquire its bioactive conformation; this explained some puzzling results of ,serine-trap' type inhibitors. A more complete study on NS3 activation, however, requires the availability of the full-length NS4A protein. This was prepared by native chemical ligation, after sequence engineering to enhance its solubility; structural studies are in progress. Current work is focused on the P, region of the substrate, which, at variance with the P region, is not used for ground state binding to the enzyme and might give rise to inhibitors showing novel interactions with the enzyme. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd. [source] Effects of long-term chilling on growth and photosynthesis of the C4 gramineae Paspalum dilatatumPHYSIOLOGIA PLANTARUM, Issue 1 2003Ana M. Cavaco Dallis grass (Paspalum dilatatum Poir.) is a C4/NADP-ME gramineae, previously classified as semi-tolerant to cold, although a complete study on this species acclimation process under a long-term chilling and controlled environmental conditions has never been conducted. In the present work, plants of the variety Raki maintained at 25/18°C (day/night) (control) were compared with plants under a long-term chilling at 10/8°C (day/night) (cold-acclimated) in order to investigate how growth and carbon assimilation mechanisms are engaged in P. dilatatum chilling tolerance. Although whole plant mean relative growth rate (mean RGR) and leaf growth were significantly decreased by cold exposure, chilling did not impair plant development nor favour the investment in biomass below ground. Cold-acclimated P. dilatatum cv. Raki had a lower leaf chlorophyll content, but a higher photosynthetic capacity at optimal temperatures, its range being shifted to lower values. Associated with this higher capacity to use the reducing power in CO2 assimilation, cold-acclimated plants further showed a higher capacity to oxidize the primary stable quinone electron acceptor of PSII, QA. The activity and activation of phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) were not significantly affected by the long-term chilling. Cold-acclimated P. dilatatum cv. Raki apparently showed a lower transfer of excitation energy from the light-harvesting complex of photosystem II to the respective reaction centre and enhancement of radiationless energy-dissipating mechanisms at suboptimal temperatures. Overall, long-term chilling resulted in several effects that comprise responses with an intermediate character of both chilling-tolerant and ,sensitive plants, which seem to play a significant role in the survival and acclimation of P. dilatatum cv. Raki at low temperature. [source] Lung eNOS and iNOS are Reoxygenation Time-Dependent Upregulated After Acute HypoxiaTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 6 2010Alma Rus Abstract Nitric oxide plays a critical role in many physiological and physiopathological processes in the lung. Changes in the NO/NOS (Nitric Oxide/Nitric Oxide Synthase) system after hypoxia situations remain controversial in this organ, so that the aim of this work is to perform a complete study of this system in the hypoxic lung after different reoxygenation times ranging from 0 h to 5 days posthypoxia. This is a novel follow-up study carried out in Wistar rats submitted for 30 min to acute hypobaric hypoxia. We measured endothelial and inducible NOS (eNOS, iNOS) mRNA and protein expression, location, and in situ NOS activity as well as nitrated protein expression and location. In addition, NO levels were indirectly quantified (NOx) as well as the apoptosis level. Results showed an increase in eNOS mRNA, protein, activity as well as eNOS positive immunostaining at 0 h posthypoxia, coinciding with raised NOx levels. Contrary, iNOS, nitrated protein expression and apoptosis level augmented during the final reoxygenation times. The lung NO/NOS system provokes two responses to the hypoxia/reoxygenation processes: (i) eNOS is responsible of the immediate response, producing NO, which causes vasodilation and bronchodilation, and (ii) iNOS is related to the second late response, which seems to be involved in some of the deleterious consequences that hypoxia induces in the lung. Anat Rec, 2010. © 2010 Wiley-Liss, Inc. [source] Observability of Depth Estimation for a Hand-Eye Robot SystemASIAN JOURNAL OF CONTROL, Issue 3 2002Chang-Jia Fang ABSTRACT This paper deals with the depth observability problem of a hand-eye robot system. In contrast to earlier works, this paper presents a complete study of this observability problem. The velocity of the active camera in the hand-eye robot system is considered as the input. The observability of depth estimation is then related to the velocity of the camera. A necessary and sufficient condition for the types of camera velocities necessary to ensure observability is found. This compensates for the results of earlier works, in which the velocity of camera was estimated. The theory is also verified by both simulations and experiments in this paper. Furthermore, a modified LQ visual servo control law is proposed to vary the weighting matrices so that depth estimation is improved while the level of control performance is still retained. [source] Molecular dynamics calculations on amylose fragments.BIOPOLYMERS, Issue 2 2002Abstract Molecular dynamics simulations (NPT ensembles, 1 atm) using the all atom force field AMB99C (F. A. Momany and J. L. Willett, Carbohydrate Research, Vol. 326, pp 194,209 and 210,226), are applied to a periodic cell containing ten maltodecaose fragments and TIP3P water molecules. Simulations were carried out at 25 K intervals over a range of temperatures above and below the expected glass transition temperature, Tg, for different water concentrations. The amorphous cell was constructed through successive dynamic equilibration steps at temperatures above Tg and the temperature lowered until several points of reduced slope (1/T vs volume) were obtained. This procedure was carried out at each hydration level. Each dynamics simulation was continued until the volume remained constant without up or down drift for at least the last 100 ps. For a given temperature, most simulations required 400,600 ps to reach an equilibrium state, but longer times were necessary as the amount of water in the cell was reduced. A total of more than 30 ns of simulations were required for the complete study. The Tg for each hydrated cell was taken as that point at which a discontinuity in slope of the volume (V), potential energy (PE), or density (,) vs 1/T was observed. The average calculated Tg values were 311, 337, 386, and 477 K for hydration levels of 15.8, 10, 5, and 1%, respectively, in generally good agreement with experimental values. The Tg for anhydrous amylose is above the decomposition temperature for carbohydrates and so cannot be easily measured. However, it has also been difficult to obtain a value of Tg for anhydrous amylose using simulation methods. Other molecular parameters such as end-to-end distances, mean square distributions, and pair distributions are discussed. Published 2002 John Wiley & Sons, Inc. Biopolymers 63: 99,110, 2002 [source] Lignin Chemistry: Biosynthetic Study and Structural Characterisation of Coniferyl Alcohol Oligomers Formed In Vitro in a Micellar EnvironmentCHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2010Samantha Reale Dr. Abstract Model coniferyl alcohol lignin (the so-called dehydrogenative polymerisate, DHP) was produced in water under homogeneous conditions guaranteed by the presence of a micellised cationic surfactant. A complete study of the activity of the enzymatic system peroxidase/H2O2 under our reaction conditions was reported and all the reaction products up to the pentamer were characterised by 1H,NMR spectroscopy and ESI mass spectrometry. Our system, and the molecules that have been generated in it, represent a closer mimicry of the natural microenvironment since an enzyme, under micellar conditions, reproduces the cell system better than in buffer alone. On the basis of the oligomers structures a new biosynthetic perspective was proposed that focused attention on a coniferyl alcohol dimeric quinone methide as the key intermediate of the reaction. A formal, strictly alternate sequence of a radical and an ionic step underlines the reaction, thus generating ordered oligolignols structures. Alternatively to other model lignins, our olignols present a lower degree of radical coupling between oligomeric units. This offers a closer biosynthetic situation to the observation of a low rate of radical generation in the cell wall. [source] Regioselectivity Control in the Metal-Catalyzed Functionalization of ,-Allenols, Part,2: Theoretical Study,CHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2009Benito Alcaide Prof. Abstract Calculating cyclization: Theoretical work directed towards the elucidation of the mechanisms of the gold-, palladium-, and lanthanum-catalyzed oxycyclizations (5- exo versus 6- endo versus 7- endo) of ,-allenols has been pursued in close relationship with the experimental study (Part,1, accompanying paper) and has corroborated the bench results to provide a complete study of the reactivity of ,-allenols under different metal-catalyzed conditions. The gold-, palladium- and lanthanum-catalyzed oxycyclization reactions of azetidin-2-one-tethered ,-allenol derivatives to a variety of fused enantiopure tetrahydrofurans, dihydropyrans, and tetrahydrooxepines have been developed experimentally (Part,1, accompanying paper). The mechanisms of these regiocontrolled metal-catalyzed heterocyclization reactions have now been computationally explored at the DFT level (Part,2). The energies of the reaction intermediates and transition states for different possible pathways have been calculated in various model systems very close to the real system. Additionally, we selected the La[N(SiH3)2]3 complex to simulate the lanthanide amide precatalyst species. The agreement of theoretically predicted and experimentally observed selectivities is very good in all cases La reacción de heterociclación de , -alenoles catalizada por metales es un proceso regiocontrolado que da lugar a una amplia variedad de tetrahidrofuranos, tetrahidropiranos y tetrahidrooxepinas fusionadas enantiopuras, que contienen además un anillo ,-lactámico, que es la unidad estructural clave en productos biológicos relevantes como antibióticos e inhibidores enzimáticos. Se ha llevado a cabo un estudio teórico para la elucidación de los mecanismos de estas ciclaciones catalizadas por oro, paladio y lantano, en estrecha relación con el trabajo experimental (Parte,1, artículo anterior), corroborando los resultados obtenidos en el laboratorio. [source] | ||||||||||||||||