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C Values (c + value)
Selected AbstractsThrombin generation in haemophilia A patients with mutations causing factor VIII assay discrepancyHAEMOPHILIA, Issue 4 2010R. GILMORE Summary., Up to 40% of patients with mild haemophilia A have a discrepancy whereby factor VIII (FVIII) measurements by a two-stage chromogenic assay (FVIII:CCH) are disproportionately reduced compared with the FVIII one-stage clotting value (FVIII:C). Which assay best reflects the coagulation potential and clinical phenotype in this patient group is of clinical significance, yet remains unclear. We have assessed the global coagulant ability of haemophilia patients with FVIII assay discrepancy using calibrated automated thrombography (CAT). A total of 18 patients with mutations Arg531His/Cys or Arg698Trp causing FVIII discrepancy were investigated, together with 12 haemophilia patients with concordant FVIII values and 15 normal controls. Factor VIII levels in all patients and controls were measured using both one-stage clotting assay and two-stage chromogenic assay. Thrombin generation was assessed in platelet-poor plasma by CAT using a low tissue factor concentration (1 pm). FVIII:CCH values were below normal in all patients, and in the discrepant group were between 1.5- and 8-fold lower than FVIII:C values. CAT parameters were affected in all haemophilia patients. The endogenous thrombin potential (ETP) was reduced to 58,67% of the mean normal value (1301 nm min,1), whereas peak thrombin was further reduced to 27,30% of the mean normal value (178 nm) in both discrepant and concordant patient groups. Analysis of the discrepant patient group showed the most significant correlation between the one-stage FVIII:C assay and ETP (r2 = 0.44) and peak thrombin parameters (r2 = 0.27). [source] An evolutionary optimization of diffuser shapes based on CFD simulationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2010S. Ghosh Abstract An efficient and robust algorithm is presented for the optimum design of plane symmetric diffusers handling incompressible turbulent flow. The indigenously developed algorithm uses the CFD software: Fluent for the hydrodynamic analysis and employs a genetic algorithm (GA) for optimization. For a prescribed inlet velocity and outlet pressure, pressure recovery coefficient C (the objective function) is estimated computationally for various design options. The CFD software and the GA have been combined in a monolithic platform for a fully automated operation using some special control commands. Based on the developed algorithm, an extensive exercise has been made to optimize the diffuser shape. Different methodologies have been adopted to create a large number of design options. Interestingly, not much difference has been noted in the optimum C values obtained through different approaches. However, in all the approaches, a better design has been obtained through a proper selection of the number of design variables. Finally, the effect of diffuser length on the optimum shape has also been studied. Copyright © 2009 John Wiley & Sons, Ltd. [source] Kinetic study of the free-radical polymerization of vinyl acetate in the presence of deuterated chloroform by 1H-NMR spectroscopyJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Mohammad Ali Semsarzadeh Abstract The free-radical polymerization of vinyl acetate was performed in the presence of deuterated chloroform (CDCl3) as a chain-transfer agent (telogen) and 2,2,-azobisisobutyronitrile as an initiator. The effects of the initiator and solvent concentrations (or equivalent monomer concentration) and the reaction temperature on the reaction kinetics were studied by real-time 1H-NMR spectroscopy. Data obtained from analysis of the 1H-NMR spectra were used to calculate some kinetic parameters, such as the initiator decomposition rate constant (kd), kp(f/kt)1/2 ratio (where kp is the average rate constant for propagation, f is the initiator efficiency, and kt is the average rate constant for termination), and transfer constant to CDCl3 (C). The results show that kd and kp(f/kt)1/2 changed significantly with the solvent concentration and reaction temperature, whereas they remained almost constant with the initiator concentration. C changed only with the reaction temperature. Attempts were made to explain the dependence of kp(f/kt)1/2 on the solvent concentration. We concluded from the solvent-independent C values that the solvent did not have any significant effect on the kp values. As a result, changes in the kp(f/kt)1/2 values with solvent concentration were attributed to the solvent effect on the f and/or kt values. Individual values of f and kt were estimated, and we observed that both the f and kt values were dependent on the solvent (or equivalent monomer) concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] The analysis of indexed astronomical time series , X. Significance testing of O,C dataMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2006Chris Koen ABSTRACT It is assumed that O,C (,observed minus calculated') values of periodic variable stars are determined by three processes, namely measurement errors, random cycle-to-cycle jitter in the period, and possibly long-term changes in the mean period. By modelling the latter as a random walk, the covariances of all O,C values can be calculated. The covariances can then be used to estimate unknown model parameters, and to choose between alternative models. Pseudo-residuals which could be used in model fit assessment are also defined. The theory is illustrated by four applications to spotted stars in eclipsing binaries. [source] Effect of X-Radiation on Lipid Peroxidation and Antioxidant Systems in Rats Treated with Saponin-containing CompoundsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2008Omer Yalinkilic The aim of this study was to investigate the effect of three saponin-containing plant species extracts (Aesculuc hippocastanum L. seed extract [AHE], Medicago sativa L. extract [MSE] and Spinacia oleracea L. extract [SOE]) on lipid peroxidation and on antioxidant systems in rats exposed to X-rays (XR). The rats were divided into three categories. The first category served as controls and received only a standard diet. The second category served as the radiation group and received 5 and 10 Gy XR dose. The third category (XR+extract-treated) received plant extracts (25.0 or 50.0 mg kg,1 live weight) and 5 or 10 Gy XR dose. Blood samples were analyzed for their content of malondialdehyde (MDA), reduced glutathione (GSH), plasma vitamin C, ,-carotene and retinol. In animals receiving XR, the plasma MDA (P < 0.001) value significantly increased but the level of GSH (P < 0.01), vitamin C (P < 0.001), retinol and ,-carotene (P < 0.001) decreased significantly with increasing XR doses. In the XR+extract-treated groups, the concentrations of MDA increased significantly with increasing radiation but their concentrations decreased significantly with increasing extract concentrations. Plasma concentrations of GSH, ,-carotene, retinol and vitamin C in XR+extract-treated groups decreased significantly with increasing XR dose but their concentrations increased with increasing extract doses. Further, comparison of blood samples of XR+extract-treated groups with those from the control group showed that GSH, ,-carotene, retinol and vitamin C values increased significantly but that MDA values decreased significantly. The results showed that all extracts have enhanced the antioxidant status and decreased the incidence of free radical-induced lipid peroxidation in blood samples of rats exposed to XR. However, the antioxidant effect of AHE-administered animals was more effective than that of MSE- and SOE-administered whole-body XR rats. We conclude that the supplementation with saponin-containing extracts may serve to reinforce the antioxidant systems, thus having protective effect against cell damage by XR. [source] Design and Costs of a Measurement Protocol for Trades in Soil Carbon CreditsCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 3 2004Siân Mooney Previous work has demonstrated that in the absence of transaction costs, contracts that pay producers per carbon (C) credit are more efficient than those that tie payments to changes in management practices. In this paper we develop a measurement protocol to support contracts for C credits and estimate its implementation costs using an empirical example. We find that the costs of implementing a measurement protocol for soil C credits depend on: the price of credits; the regional heterogeneity in C values as well as assumed error and confidence intervals. We find that the upper estimate of measurement costs associated with a contract that pays producers per C credit can be as little as 3% of the value of a credit. These contract measurement costs are less than the efficiency gains from implementing a per-credit contract. Des travaux antérieurs montrent que si la transaction ne coûte rien, les ententes prévoyant la rémuné ration des agriculteurs par cré dit carbone (C) sont plus efficaces que celles oè les paiements sont lié s à l'adaptation des pratiques culturales. Dans leur article, les auteurs proposent une mé thode de calculpour de telles ententes et estiment ce que coûterait son implantation au moyen d'un exemple empirique. On constate que, pour les cré dits C du sol, le coût de mise en æuvre dépend du prix des cré dits, de l'hé térogénéité régionale de la valeur des crédits ainsi que dxe l'erreur présumée et des intervalles de confiance. On se rend compte que la plus haute estimation du coût des ententes rémunérant les agriculteurs enfonction des crédits C ne dépasse pas trois pour cent de la valeur du crédit. De tels coûts sont inférieurs aux gains de productivité résultant de l'adoption d'une entente articulée sur les crédits C. [source] Prediction of Tyrosinase Inhibition Activity Using Atom-Based Bilinear IndicesCHEMMEDCHEM, Issue 4 2007Yovani Marrero-Ponce Prof. Abstract A set of novel atom-based molecular fingerprints is proposed based on a bilinear map similar to that defined in linear algebra. These molecular descriptors (MDs) are proposed as a new means of molecular parametrization easily calculated from 2D molecular information. The nonstochastic and stochastic molecular indices match molecular structure provided by molecular topology by using the kth nonstochastic and stochastic graph-theoretical electronic-density matrices, Mk and Sk, respectively. Thus, the kth nonstochastic and stochastic bilinear indices are calculated using Mk and Sk as matrix operators of bilinear transformations. Chemical information is coded by using different pair combinations of atomic weightings (mass, polarizability, vdW volume, and electronegativity). The results of QSAR studies of tyrosinase inhibitors using the new MDs and linear discriminant analysis (LDA) demonstrate the ability of the bilinear indices in testing biological properties. A database of 246 structurally diverse tyrosinase inhibitors was assembled. An inactive set of 412 drugs with other clinical uses was used; both active and inactive sets were processed by hierarchical and partitional cluster analyses to design training and predicting sets. Twelve LDA-based QSAR models were obtained, the first six using the nonstochastic total and local bilinear indices and the last six with the stochastic MDs. The discriminant models were applied; globally good classifications of 99.58 and 89.96,% were observed for the best nonstochastic and stochastic bilinear indices models in the training set along with high Matthews correlation coefficients (C) of 0.99 and 0.79, respectively, in the learning set. External prediction sets used to validate the models obtained were correctly classified, with accuracies of 100 and 87.78,%, respectively, yielding C values of 1.00 and 0.73. This subset contains 180 active and inactive compounds not considered to fit the models. A simulated virtual screen demonstrated this approach in searching tyrosinase inhibitors from compounds never considered in either training or predicting series. These fitted models permitted the selection of new cycloartane compounds isolated from herbal plants as new tyrosinase inhibitors. A good correspondence between theoretical and experimental inhibitory effects on tyrosinase was observed; compound CA6 (IC50=1.32,,M) showed higher activity than the reference compounds kojic acid (IC50=16.67,,M) and L -mimosine (IC50=3.68,,M). [source] Base-Metal-Electroded BaTiO3 Capacitor Materials with Duplex MicrostructuresJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2004I-Nan Lin The effect of dopants and processing conditions on the dielectric properties of base-metal-electroded materials was investigated. BaTiO3 materials simultaneously doped with MgO and Y2O3 additives can achieve small capacitance variation (,C/C), which meets the X7R specification, when the proportion of additives is abundant enough and the materials are not over-fired. Presumably, small ,C/C values of thus obtained materials are the result of the formation of core,shell structure, which requires stringent control of material processing conditions. In contrast, X7R-type materials can be obtained in a much wider processing window, when prepared by mixing two BaTiO3 materials of suitable dielectric constant,temperature (K,T) characteristics. Duplexed materials prepared from these two end-point BaTiO3 materials with ratios ranging from 3:1 to 1:2 exhibit K,T behavior within the X7R specification, provided that one of the components possesses flat K,T behavior. Moreover, the dielectric properties of these materials were simulated using a simplified microstructural model. Simulation results indicate that the effective dielectric constant of core,shell materials, (Ke)CS, varies significantly not only with the dielectric properties of cores and shells, but also with the shell-to-core thickness ratio, whereas the effective dielectric constant of duplexed materials, (Ke)D, can be maintained at a very small ,C/C value for a wide range of end-point constituent ratios, which agrees very well with the measured K,T properties for the materials. [source] | ||||||||||