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Sample records for michaelis-menten mechanism continuous

  1. The Michaelis-Menten-Stueckelberg Theorem

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    Alexander N. Gorban

    2011-05-01

    Full Text Available We study chemical reactions with complex mechanisms under two assumptions: (i intermediates are present in small amounts (this is the quasi-steady-state hypothesis or QSS and (ii they are in equilibrium relations with substrates (this is the quasiequilibrium hypothesis or QE. Under these assumptions, we prove the generalized mass action law together with the basic relations between kinetic factors, which are sufficient for the positivity of the entropy production but hold even without microreversibility, when the detailed balance is not applicable. Even though QE and QSS produce useful approximations by themselves, only the combination of these assumptions can render the possibility beyond the “rarefied gas” limit or the “molecular chaos” hypotheses. We do not use any a priori form of the kinetic law for the chemical reactions and describe their equilibria by thermodynamic relations. The transformations of the intermediate compounds can be described by the Markov kinetics because of their low density (low density of elementary events. This combination of assumptions was introduced by Michaelis and Menten in 1913. In 1952, Stueckelberg used the same assumptions for the gas kinetics and produced the remarkable semi-detailed balance relations between collision rates in the Boltzmann equation that are weaker than the detailed balance conditions but are still sufficient for the Boltzmann H-theorem to be valid. Our results are obtained within the Michaelis-Menten-Stueckelbeg conceptual framework.

  2. Reexamining Michaelis-Menten Enzyme Kinetics for Xanthine Oxidase

    Science.gov (United States)

    Bassingthwaighte, James B.; Chinn, Tamara M.

    2013-01-01

    Abbreviated expressions for enzyme kinetic expressions, such as the Michaelis-Menten (M-M) equations, are based on the premise that enzyme concentrations are low compared with those of the substrate and product. When one does progress experiments, where the solute is consumed during conversion to form a series of products, the idealized conditions…

  3. Stability estimation of autoregulated genes under Michaelis-Menten-type kinetics

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    Arani, Babak M. S.; Mahmoudi, Mahdi; Lahti, Leo; González, Javier; Wit, Ernst C.

    2018-06-01

    Feedback loops are typical motifs appearing in gene regulatory networks. In some well-studied model organisms, including Escherichia coli, autoregulated genes, i.e., genes that activate or repress themselves through their protein products, are the only feedback interactions. For these types of interactions, the Michaelis-Menten (MM) formulation is a suitable and widely used approach, which always leads to stable steady-state solutions representative of homeostatic regulation. However, in many other biological phenomena, such as cell differentiation, cancer progression, and catastrophes in ecosystems, one might expect to observe bistable switchlike dynamics in the case of strong positive autoregulation. To capture this complex behavior we use the generalized family of MM kinetic models. We give a full analysis regarding the stability of autoregulated genes. We show that the autoregulation mechanism has the capability to exhibit diverse cellular dynamics including hysteresis, a typical characteristic of bistable systems, as well as irreversible transitions between bistable states. We also introduce a statistical framework to estimate the kinetics parameters and probability of different stability regimes given observational data. Empirical data for the autoregulated gene SCO3217 in the SOS system in Streptomyces coelicolor are analyzed. The coupling of a statistical framework and the mathematical model can give further insight into understanding the evolutionary mechanisms toward different cell fates in various systems.

  4. Dynamic disorder in single-molecule Michaelis-Menten kinetics: The reaction-diffusion formalism in the Wilemski-Fixman approximation

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    Chaudhury, Srabanti; Cherayil, Binny J.

    2007-09-01

    Single-molecule equations for the Michaelis-Menten [Biochem. Z. 49, 333 (1913)] mechanism of enzyme action are analyzed within the Wilemski-Fixman [J. Chem. Phys. 58, 4009 (1973); 60, 866 (1974)] approximation after the effects of dynamic disorder—modeled by the anomalous diffusion of a particle in a harmonic well—are incorporated into the catalytic step of the reaction. The solution of the Michaelis-Menten equations is used to calculate the distribution of waiting times between successive catalytic turnovers in the enzyme β-galactosidase. The calculated distribution is found to agree qualitatively with experimental results on this enzyme obtained at four different substrate concentrations. The calculations are also consistent with measurements of correlations in the fluctuations of the fluorescent light emitted during the course of catalysis, and with measurements of the concentration dependence of the randomness parameter.

  5. Stability in a Simple Food Chain System with Michaelis-Menten Functional Response and Nonlocal Delays

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    Wenzhen Gan

    2013-01-01

    Full Text Available This paper is concerned with the asymptotical behavior of solutions to the reaction-diffusion system under homogeneous Neumann boundary condition. By taking food ingestion and species' moving into account, the model is further coupled with Michaelis-Menten type functional response and nonlocal delay. Sufficient conditions are derived for the global stability of the positive steady state and the semitrivial steady state of the proposed problem by using the Lyapunov functional. Our results show that intraspecific competition benefits the coexistence of prey and predator. Furthermore, the introduction of Michaelis-Menten type functional response positively affects the coexistence of prey and predator, and the nonlocal delay is harmless for stabilities of all nonnegative steady states of the system. Numerical simulations are carried out to illustrate the main results.

  6. Patterns induced by super cross-diffusion in a predator-prey system with Michaelis-Menten type harvesting.

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    Liu, Biao; Wu, Ranchao; Chen, Liping

    2018-04-01

    Turing instability and pattern formation in a super cross-diffusion predator-prey system with Michaelis-Menten type predator harvesting are investigated. Stability of equilibrium points is first explored with or without super cross-diffusion. It is found that cross-diffusion could induce instability of equilibria. To further derive the conditions of Turing instability, the linear stability analysis is carried out. From theoretical analysis, note that cross-diffusion is the key mechanism for the formation of spatial patterns. By taking cross-diffusion rate as bifurcation parameter, we derive amplitude equations near the Turing bifurcation point for the excited modes by means of weakly nonlinear theory. Dynamical analysis of the amplitude equations interprets the structural transitions and stability of various forms of Turing patterns. Furthermore, the theoretical results are illustrated via numerical simulations. Copyright © 2018. Published by Elsevier Inc.

  7. Classical Michaelis-Menten and system theory approach to modeling metabolite formation kinetics.

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    Popović, Jovan

    2004-01-01

    When single doses of drug are administered and kinetics are linear, techniques, which are based on the compartment approach and the linear system theory approach, in modeling the formation of the metabolite from the parent drug are proposed. Unlike the purpose-specific compartment approach, the methodical, conceptual and computational uniformity in modeling various linear biomedical systems is the dominant characteristic of the linear system approach technology. Saturation of the metabolic reaction results in nonlinear kinetics according to the Michaelis-Menten equation. The two compartment open model with Michaelis-Menten elimination kinetics is theorethicaly basic when single doses of drug are administered. To simulate data or to fit real data using this model, one must resort to numerical integration. A biomathematical model for multiple dosage regimen calculations of nonlinear metabolic systems in steady-state and a working example with phenytoin are presented. High correlation between phenytoin steady-state serum levels calculated from individual Km and Vmax values in the 15 adult epileptic outpatients and the observed levels at the third adjustment of phenytoin daily dose (r=0.961, p<0.01) were found.

  8. Diffusion influence on Michaelis Menten kinetics: II. The low substrate concentration limit

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    Kim, Hyojoon; Shin, Kook Joe

    2007-02-01

    The diffusion-influenced Michaelis-Menten kinetics in the low substrate concentration limit is studied in one and three dimensions. For the initial pair distribution of enzyme and substrate, we obtain the exact analytical results. We find that at short times the diffusion effect can make the reaction rate faster. The concentration deviations of the substrate and enzyme show t-1/2 and t-3/2 power-law behaviours in one and three dimensions, respectively, at long times. On the other hand, the average lifetime of the intermediate is independent of the initial state in one dimension, while it depends on the initial state in three dimensions. The ultimate production yield approaches unity in one dimension but it reaches a different value depending on other parameters in three dimensions. We also obtain the analytical results for the initial random distribution.

  9. Diffusion influence on Michaelis-Menten kinetics: II. The low substrate concentration limit

    International Nuclear Information System (INIS)

    Kim, Hyojoon; Shin, Kook Joe

    2007-01-01

    The diffusion-influenced Michaelis-Menten kinetics in the low substrate concentration limit is studied in one and three dimensions. For the initial pair distribution of enzyme and substrate, we obtain the exact analytical results. We find that at short times the diffusion effect can make the reaction rate faster. The concentration deviations of the substrate and enzyme show t -1/2 and t -3/2 power-law behaviours in one and three dimensions, respectively, at long times. On the other hand, the average lifetime of the intermediate is independent of the initial state in one dimension, while it depends on the initial state in three dimensions. The ultimate production yield approaches unity in one dimension but it reaches a different value depending on other parameters in three dimensions. We also obtain the analytical results for the initial random distribution

  10. Why plankton modellers should reconsider using rectangular hyperbolic (Michaelis-Menten, Monod descriptions of predator-prey interactions

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    Kevin John Flynn

    2016-09-01

    Full Text Available Rectangular hyperbolic type 2 (RHt2; Michaelis-Menten or Monod -like functions are commonly used to describe predation kinetics in plankton models, either alone or together with a prey selectivity algorithm deploying the same half-saturation constant for all prey types referenced to external prey biomass abundance. We present an analysis that indicates that such descriptions are liable to give outputs that are not plausible according to encounter theory. This is especially so for multi-prey type applications or where changes are made to the maximum feeding rate during a simulation. The RHt2 approach also gives no or limited potential for descriptions of events such as true de-selection of prey, effects of turbulence on encounters, or changes in grazer motility with satiation. We present an alternative, which carries minimal parameterisation effort and computational cost, linking allometric algorithms relating prey abundance and encounter rates to a prey-selection function controlled by satiation. The resultant Satiation-Controlled-Encounter-Based (SCEB function provides a flexible construct describing numeric predator-prey interactions with biomass-feedback control of grazing. The SCEB function includes an attack component similar to that in the Holling disk equation but SCEB differs in having only a single (satiation-based handling constant and an explicit maximum grazing rate. We argue that there is no justification for continuing to deploy RHt2 functions to describe plankton predator-prey interactions.

  11. Biphasic character of ribosomal translocation and non-Michaelis-Menten kinetics of translation

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    Xie, Ping

    2014-12-01

    We study theoretically the kinetics of mRNA translocation in the wild-type (WT) Escherichia coli ribosome, which is composed of a small 30 S and large 50 S subunit, and the ribosomes with mutations to some intersubunit bridges such as B1a, B4, B7a, and B8. The theoretical results reproduce well the available in vitro experimental data on the biphasic kinetics of the forward mRNA translocation catalyzed by elongation factor G (EF-G) hydrolyzing GTP, which can be best fit by the sum of two exponentials, and the monophasic kinetics of the spontaneous reverse mRNA translocation in the absence of the elongation factor, which can be best fit by a single-exponential function, in both the WT and mutant ribosomes. We show that both the mutation-induced increase in the maximal rate of the slow phase for the forward mRNA translocation and that in the rate of the spontaneous reverse mRNA translocation result from a reduction in the intrinsic energy barrier to resist the rotational movements between the two subunits, giving the same degree of increase in the two rates. The mutation-induced increase in the maximal rate of the fast phase for the forward mRNA translocation results mainly from the increase in the rate of the ribosomal unlocking, a conformational change in the ribosome that widens the mRNA channel for the mRNA translocation to take place, which could be partly due to the effect of the mutation on the intrasubunit 30S head rotation. Moreover, we study the translation rate of the WT and mutant ribosomes. It is shown that the translation rate versus the concentration of EF-G-GTP does not follow the Michaelis-Menten (MM) kinetics, which is in sharp contrast to the general property of other enzymes that the rate of the enzymatic reaction versus the concentration of a substrate follows the MM kinetics. The physical origin of this non-MM kinetics for the ribosome is revealed.

  12. Exact and approximate solutions for the decades-old Michaelis-Menten equation: Progress-curve analysis through integrated rate equations.

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    Goličnik, Marko

    2011-01-01

    The Michaelis-Menten rate equation can be found in most general biochemistry textbooks, where the time derivative of the substrate is a hyperbolic function of two kinetic parameters (the limiting rate V, and the Michaelis constant K(M) ) and the amount of substrate. However, fundamental concepts of enzyme kinetics can be difficult to understand fully, or can even be misunderstood, by students when based only on the differential form of the Michaelis-Menten equation, and the variety of methods available to calculate the kinetic constants from rate versus substrate concentration "textbook data." Consequently, enzyme kinetics can be confusing if an analytical solution of the Michaelis-Menten equation is not available. Therefore, the still rarely known exact solution to the Michaelis-Menten equation is presented here through the explicit closed-form equation in terms of the Lambert W(x) function. Unfortunately, as the W(x) is not available in standard curve-fitting computer programs, the practical use of this direct solution is limited for most life-science students. Thus, the purpose of this article is to provide analytical approximations to the equation for modeling Michaelis-Menten kinetics. The elementary and explicit nature of these approximations can provide students with direct and simple estimations of kinetic parameters from raw experimental time-course data. The Michaelis-Menten kinetics studied in the latter context can provide an ideal alternative to the 100-year-old problems of data transformation, graphical visualization, and data analysis of enzyme-catalyzed reactions. Hence, the content of the course presented here could gradually become an important component of the modern biochemistry curriculum in the 21st century. Copyright © 2011 Wiley Periodicals, Inc.

  13. Occurrence of dead core in catalytic particles containing immobilized enzymes: analysis for the Michaelis-Menten kinetics and assessment of numerical methods.

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    Pereira, Félix Monteiro; Oliveira, Samuel Conceição

    2016-11-01

    In this article, the occurrence of dead core in catalytic particles containing immobilized enzymes is analyzed for the Michaelis-Menten kinetics. An assessment of numerical methods is performed to solve the boundary value problem generated by the mathematical modeling of diffusion and reaction processes under steady state and isothermal conditions. Two classes of numerical methods were employed: shooting and collocation. The shooting method used the ode function from Scilab software. The collocation methods included: that implemented by the bvode function of Scilab, the orthogonal collocation, and the orthogonal collocation on finite elements. The methods were validated for simplified forms of the Michaelis-Menten equation (zero-order and first-order kinetics), for which analytical solutions are available. Among the methods covered in this article, the orthogonal collocation on finite elements proved to be the most robust and efficient method to solve the boundary value problem concerning Michaelis-Menten kinetics. For this enzyme kinetics, it was found that the dead core can occur when verified certain conditions of diffusion-reaction within the catalytic particle. The application of the concepts and methods presented in this study will allow for a more generalized analysis and more accurate designs of heterogeneous enzymatic reactors.

  14. Complex dynamics of a stochastic discrete modified Leslie-Gower predator-prey model with Michaelis-Menten type prey harvesting

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    A. Elhassanein

    2014-06-01

    Full Text Available This paper introduced a stochastic discretized version of the modified Leslie-Gower predator-prey model with Michaelis-Menten type prey harvesting. The dynamical behavior of the proposed model was investigated. The existence and stability of the equilibria of the skeleton were studied. Numerical simulations were employed to show the model's complex dynamics by means of the largest Lyapunov exponents, bifurcations, time series diagrams and phase portraits. The effects of noise intensity on its dynamics and the intermittency phenomenon were also discussed via simulation.

  15. Utilization of integrated Michaelis-Menten equations for enzyme inhibition diagnosis and determination of kinetic constants using Solver supplement of Microsoft Office Excel.

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    Bezerra, Rui M F; Fraga, Irene; Dias, Albino A

    2013-01-01

    Enzyme kinetic parameters are usually determined from initial rates nevertheless, laboratory instruments only measure substrate or product concentration versus reaction time (progress curves). To overcome this problem we present a methodology which uses integrated models based on Michaelis-Menten equation. The most severe practical limitation of progress curve analysis occurs when the enzyme shows a loss of activity under the chosen assay conditions. To avoid this problem it is possible to work with the same experimental points utilized for initial rates determination. This methodology is illustrated by the use of integrated kinetic equations with the well-known reaction catalyzed by alkaline phosphatase enzyme. In this work nonlinear regression was performed with the Solver supplement (Microsoft Office Excel). It is easy to work with and track graphically the convergence of SSE (sum of square errors). The diagnosis of enzyme inhibition was performed according to Akaike information criterion. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  16. At the centennial of Michaelis and Menten, competing Michaelis-Menten steps explain effect of GLP-1 on blood-brain transfer and metabolism of glucose.

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    Gejl, Michael; Rungby, Jørgen; Brock, Birgitte; Gjedde, Albert

    2014-08-01

    Glucagon-like peptide-1 (GLP-1) is a potent insulinotropic incretin hormone with both pancreatic and extrapancreatic effects. Studies of GLP-1 reveal significant effects in regions of brain tissue that regulate appetite and satiety. GLP-1 mimetics are used for the treatment of type 2 diabetes mellitus. GLP-1 interacts with peripheral functions in which the autonomic nervous system plays an important role, and emerging pre-clinical findings indicate a potential neuroprotective role of the peptide, for example in models of stroke and in neurodegenerative disorders. A century ago, Leonor Michaelis and Maud Menten described the steady-state enzyme kinetics that still apply to the multiple receptors, transporters and enzymes that define the biochemical reactions of the brain, including the glucose-dependent impact of GLP-1 on blood-brain glucose transfer and metabolism. This MiniReview examines the potential of GLP-1 as a molecule of interest for the understanding of brain energy metabolism and with reference to the impact on brain metabolism related to appetite and satiety regulation, stroke and neurodegenerative disorders. These effects can be understood only by reference to the original formulation of the Michaelis-Menten equation as applied to a chain of kinetically controlled steps. Indeed, the effects of GLP-1 receptor activation on blood-brain glucose transfer and brain metabolism of glucose depend on the glucose concentration and relative affinities of the steps both in vitro and in vivo, as in the pancreas. © 2014 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

  17. Determination of the Michaelis-Menten kinetics and the genes expression involved in phyto-degradation of cyanide and ferri-cyanide.

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    Yu, Xiao-Zhang; Zhang, Xue-Hong

    2016-07-01

    Hydroponic experiments were conducted with different species of plants (rice, maize, soybean and willow) exposed to ferri-cyanide to investigate the half-saturation constant (K M ) and the maximal metabolic capacity (v max ) involved in phyto-assimilation. Three varieties for each testing species were collected from different origins. Measured concentrations show that the uptake rates responded biphasically to ferri-cyanide treatments by showing increases linearly at low and almost constant at high concentrations from all treatments, indicating that phyto-assimilation of ferri-cyanide followed the Michaelis-Menten kinetics. Using non-linear regression, the highest v max was by rice, followed by willows. The lowest v max was found for soybean. All plants, except maize (DY26) and rice (XJ12), had a similar K M value, suggesting the same enzyme was active in phyto-assimilation of ferri-cyanide. Transcript level, by real-time quantitative PCR, of enzymes involved in degradation of cyanides showed that the analyzed genes were differently expressed during different cyanides exposure. The expression of CAS and ST genes responded positively to KCN exposure, suggesting that β-CAS and ST pathways were two possible pathways for cyanide detoxification in rice. The transcript level of NIT and ASPNASE genes also showed a remarkable up-regulation to KCN, implying the contribution to the pool of amino acid aspartate, which is an end product of CN metabolism. Up-regulation of GS genes suggests that acquisition of ammonium released from cyanide degradation may be an additional nitrogen source for plant nutrition. Results also revealed that the expressions of these genes, except for GS, were relatively constant during iron cyanide exposure, suggesting that they are likely metabolized by plants through a non-defined pathway rather than the β-CAS pathway.

  18. Microscale Measurements of Michaelis-Menten Constants of Neuraminidase with Nanogel Capillary Electrophoresis for the Determination of the Sialic Acid Linkage.

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    Gattu, Srikanth; Crihfield, Cassandra L; Holland, Lisa A

    2017-01-03

    Phospholipid nanogels enhance the stability and performance of the exoglycosidase enzyme neuraminidase and are used to create a fixed zone of enzyme within a capillary. With nanogels, there is no need to covalently immobilize the enzyme, as it is physically constrained. This enables rapid quantification of Michaelis-Menten constants (K M ) for different substrates and ultimately provides a means to quantify the linkage (i.e., 2-3 versus 2-6) of sialic acids. The fixed zone of enzyme is inexpensive and easily positioned in the capillary to support electrophoresis mediated microanalysis using neuraminidase to analyze sialic acid linkages. To circumvent the limitations of diffusion during static incubation, the incubation period is reproducibly achieved by varying the number of forward and reverse passes the substrate makes through the stationary fixed zone using in-capillary electrophoretic mixing. A K M value of 3.3 ± 0.8 mM (V max , 2100 ± 200 μM/min) was obtained for 3'-sialyllactose labeled with 2-aminobenzoic acid using neuraminidase from Clostridium perfringens that cleaves sialic acid monomers with an α2-3,6,8,9 linkage, which is similar to values reported in the literature that required benchtop analyses. The enzyme cleaves the 2-3 linkage faster than the 2-6, and a K M of 2 ± 1 mM (V max , 400 ± 100 μM/min) was obtained for the 6'-sialyllactose substrate. An alternative neuraminidase selective for 2-3 sialic acid linkages generated a K M value of 3 ± 2 mM (V max , 900 ± 300 μM/min) for 3'-sialyllactose. With a knowledge of V max , the method was applied to a mixture of 2-3 and 2-6 sialyllactose as well as 2-3 and 2-6 sialylated triantennary glycan. Nanogel electrophoresis is an inexpensive, rapid, and simple alternative to current technologies used to distinguish the composition of 3' and 6' sialic acid linkages.

  19. More Nuts and Bolts of Michaelis-Menten Enzyme Kinetics

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    Lechner, Joseph H.

    2011-01-01

    Several additions to a classroom activity are proposed in which an "enzyme" (the student) converts "substrates" (nut-bolt assemblies) into "products" (separated nuts and bolts) by unscrewing them. (Contains 1 table.)

  20. Michaelis - Menten equation for degradation of insoluble substrate

    DEFF Research Database (Denmark)

    Andersen, Morten; Kari, Jeppe; Borch, Kim

    2017-01-01

    substrate it is difficult to assess whether the requirement of the MM equation is met. In this paper we study a simple kinetic model, where removal of attack sites expose new ones which preserve the total accessible substrate, and denote this approach the substrate conserving model. The kinetic equations...... are solved in closed form, both steady states and progress curves, for any admissible values of initial conditions and rate constants. The model is shown to merge with the MM equation and the reverse MM equation when these are valid. The relation between available molar concentration of attack sites and mass...

  1. Use of Mushroom Tyrosinase to Introduce Michaelis-Menten Enzyme Kinetics to Biochemistry Students

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    Flurkey, William H.; Inlow, Jennifer K.

    2017-01-01

    An inexpensive enzyme kinetics laboratory exercise for undergraduate biochemistry students is described utilizing tyrosinase from white button mushrooms. The exercise can be completed in one or two three-hour lab sessions. The optimal amounts of enzyme, substrate (catechol), and inhibitor (kojic acid) are first determined, and then kinetic data is…

  2. Stability in a diffusive food chain model with Michaelis-Menten functional response

    DEFF Research Database (Denmark)

    Lin, Zhigui; Pedersen, Michael

    2004-01-01

    This paper deals with the behavior of positive solutions to a reaction-diffusion system with homogeneous Neumann boundary conditions describing a three species food chain. A sufficient condition for the local asymptotical stability is given by linearization and also a sufficient condition...... for the global asymptotical stability is given by a Lyapunov function. Our result shows that the equilibrium solution is globally asymptotically stable if the net birth rate of the first species is big enough and the net death rate of the third species is neither too big nor too small. (C) 2004 Elsevier Ltd. All...

  3. Response to a temperature modulation as a signature of chemical mechanisms.

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    Berthoumieux, H; Jullien, L; Lemarchand, A

    2007-11-01

    We consider n reactive species involved in unimolecular reactions and submitted to a temperature modulation of small amplitude. We determine the conditions on the rate constants for which the deviations from the equilibrium concentrations of each species can be optimized and find the analytical expression of the frequency associated with an extremum of concentration shift in the case n=3. We prove that the frequency dependence of the displacement of equilibrium gives access to the number n of species involved in the mechanism. We apply the results to the case of the transformation of a reactant into a product through a possible reactive intermediate and find the order relation obeyed by the activation energies of the different barriers. The results typically apply to enzymatic catalysis with kinetics of Michaelis-Menten type.

  4. Quantitative Evaluation of the Mechanism Underlying the Biotransportation of the Active Ingredients in Puerariae lobatae Radix and Chuanxiong rhizoma.

    Science.gov (United States)

    Liang, Xin-Li; Zhang, Jing; Liao, Zheng-Gen; Zhao, Guo-Wei; Luo, Yun; Li, Zhe; Satterlee, Andrew

    2015-06-15

    The objective of this study was to establish a quantitative method to evaluate the biotransportation of a drug across the cell membrane. Through the application of the law of mass conservation, the drug transportation rate was calculated based on Fick's law of passive diffusion and the Michaelis-Menten equation. The overall membrane-transportation rate was the sum of the passive diffusion rate and the carrier-mediated diffusion rate, which were calculated as the transportation mass divided by the respective rate. The active ingredients of Puerariae lobatae Radix and Chuanxiong rhizoma, namely, puerarin and ferulic acid, respectively, were used as two model drugs. The transportation rates of puerarin and ferulic acid were obtained by fitting a model that includes both Fick's law of diffusion and the Michaelis-Menten equation. Compared with the overall transportation, the carrier-mediated transport and passive diffusion of 1.59 mmol/L puerarin were -35.07% and 64.93%, respectively, whereas the respective transportation modes of 0.1 mmol/L ferulic acid were -35.40% and 64.60%, respectively. Verapamil and MK-571 increased the overall transport rate and ratio, and MK-571 treatment changed the carrier-mediated transport from negative to positive. However, the transport rate and ratio of ferulic acid did not change significantly. The cell transportation mechanisms of puerarin and ferulic acid primarily involve simple passive diffusion and carrier-mediated transportation. Moreover, P-glycoprotein and multidrug resistance-associated protein efflux proteins, and other transportation proteins were found to be involved in the transportation of puerarin. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Chemical Continuous Time Random Walks

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    Aquino, T.; Dentz, M.

    2017-12-01

    Traditional methods for modeling solute transport through heterogeneous media employ Eulerian schemes to solve for solute concentration. More recently, Lagrangian methods have removed the need for spatial discretization through the use of Monte Carlo implementations of Langevin equations for solute particle motions. While there have been recent advances in modeling chemically reactive transport with recourse to Lagrangian methods, these remain less developed than their Eulerian counterparts, and many open problems such as efficient convergence and reconstruction of the concentration field remain. We explore a different avenue and consider the question: In heterogeneous chemically reactive systems, is it possible to describe the evolution of macroscopic reactant concentrations without explicitly resolving the spatial transport? Traditional Kinetic Monte Carlo methods, such as the Gillespie algorithm, model chemical reactions as random walks in particle number space, without the introduction of spatial coordinates. The inter-reaction times are exponentially distributed under the assumption that the system is well mixed. In real systems, transport limitations lead to incomplete mixing and decreased reaction efficiency. We introduce an arbitrary inter-reaction time distribution, which may account for the impact of incomplete mixing. This process defines an inhomogeneous continuous time random walk in particle number space, from which we derive a generalized chemical Master equation and formulate a generalized Gillespie algorithm. We then determine the modified chemical rate laws for different inter-reaction time distributions. We trace Michaelis-Menten-type kinetics back to finite-mean delay times, and predict time-nonlocal macroscopic reaction kinetics as a consequence of broadly distributed delays. Non-Markovian kinetics exhibit weak ergodicity breaking and show key features of reactions under local non-equilibrium.

  6. In vivo measurements of brain glucose transport using the reversible michaelis-menten model and simultaneous measurements of cerebral blood flow changes during hypoglycemia

    OpenAIRE

    Choi, I.-Y.; Lee, S.-P.; Kim, S.-G.; Gruetter, R.

    2001-01-01

    Glucose is the major substrate that sustains normal brain function. When the brain glucose concentration approaches zero, glucose transport across the blood-brain barrier becomes rate limiting for metabolism during, for example, increased metabolic activity and hypoglycemia. Steady-state brain glucose concentrations in α-chloralose anesthetized rats were measured noninvasively as a function of plasma glucose. The relation between brain and plasma glucose was linear at 4.5 to 30 mmol/L plasma ...

  7. At the centennial of Michaelis and Menten, competing Michaelis-Menten steps explain effect of GLP-1 on blood-brain transfer and metabolism of glucose

    DEFF Research Database (Denmark)

    Jensen, Michael Gejl; Rungby, Jørgen; Brock, Birgitte

    2014-01-01

    Glucagon-like peptide-1 (GLP-1) is a potent insulinotropic incretin hormone with pancreatic and extrapancreatic effects. Studies reveal significant effects in regions of brain tissue that regulate appetite and satiety. The effects cause that mimetics of GLP-1 serves as treatment of type 2 diabete...

  8. Real-Time Enzyme Kinetics by Quantitative NMR Spectroscopy and Determination of the Michaelis-Menten Constant Using the Lambert-W Function

    Science.gov (United States)

    Her, Cheenou; Alonzo, Aaron P.; Vang, Justin Y.; Torres, Ernesto; Krishnan, V. V.

    2015-01-01

    Enzyme kinetics is an essential part of a chemistry curriculum, especially for students interested in biomedical research or in health care fields. Though the concept is routinely performed in undergraduate chemistry/biochemistry classrooms using other spectroscopic methods, we provide an optimized approach that uses a real-time monitoring of the…

  9. Continuous ammonium enrichment of a woodland stream: uptake kinetics, leaf decomposition, and nitrification

    Energy Technology Data Exchange (ETDEWEB)

    Newbold, J D; Elwood, J W; Schulze, M S; Stark, R W; Barmeier, J C

    1983-01-01

    In order to test for nitrogen limitation and examine ammonium uptake by stream sediments, ammonium hydroxide was added continuously at concentrations averaging 100 /sup +/gl/sup -1/ for 70 days to a second-order reach of Walker Branch, an undisturbed woodland stream in Tennessee. Ammonium uptake during the first 4 h of addition corresponded to adsorption kinetics rather than to first-order uptake or to Michaelis-Menten kinetics. However, the calculated adsorption partition coefficient was two to four orders of magnitude greater than values reported for physical adsorption of ammonium, suggesting that the uptake was largely biotic. Mass balance indicated that the uptake of ammonium from the water could be accounted for by increased nitrogen content in benthic organic detritus. Nitrification, inferred from longitudinal gradients in NO/sub 3/, began soon after enrichment and increased dramatically near the end of the experiment. Both ammonium and nitrate concentrations dropped quickly to near background levels when input ceased, indicating little desorption or nitrification of excess nitrogen stored in the reach. There was no evidence of nitrogen limitation as measured by weight loss, oxygen consumption, phosphorus content, and macroinvertebrate density of red oak leaf packs, or by chlorophyll content and aufwuchs biomass on plexiglass slides. A continuous phosphorus enrichment 1 year earlier had demonstrated phosphorus limitation in Walker Branch. 38 references, 6 figures, 3 tables.

  10. The fluid mechanics of continuous flow electrophoresis

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    Saville, D. A.

    1990-01-01

    The overall objective is to establish theoretically and confirm experimentally the ultimate capabilities of continuous flow electrophoresis chambers operating in an environment essentially free of particle sedimentation and buoyancy. The efforts are devoted to: (1) studying the effects of particle concentration on sample conductivity and dielectric constant. The dielectric constant and conductivity were identified as playing crucial roles in the behavior of the sample and on the resolving power and throughput of continuous flow devices; and (2) improving the extant mathematical models to predict flow fields and particle trajectories in continuous flow electrophoresis. A dielectric spectrometer was designed and built to measure the complex dielectric constant of a colloidal dispersion as a function of frequency between 500 Hz and 200 kHz. The real part of the signal can be related to the sample's conductivity and the imaginary part to its dielectric constant. Measurements of the dielectric constants of several different dispersions disclosed that the dielectric constants of dilute systems of the sort encountered in particle electrophoresis are much larger than would be expected based on the extant theory. Experiments were carried out to show that, in many cases, this behavior is due to the presence of a filamentary structure of small hairs on the particle surface. A technique for producing electrokinetically ideal synthetic latex particles by heat treating was developed. Given the ubiquitous nature of hairy surfaces with both cells and synthetic particles, it was deemed necessary to develop a theory to explain their behavior. A theory for electrophoretic mobility of hairy particles was developed. Finally, the extant computer programs for predicting the structure of electro-osmotically driven flows were extended to encompass flow channels with variable wall mobilities.

  11. Steady-state cerebral glucose concentrations and transport in the human brain

    OpenAIRE

    Gruetter, R.; Ugurbil, K.; Seaquist, E. R.

    1998-01-01

    Understanding the mechanism of brain glucose transport across the blood- brain barrier is of importance to understanding brain energy metabolism. The specific kinetics of glucose transport nave been generally described using standard Michaelis-Menten kinetics. These models predict that the steady- state glucose concentration approaches an upper limit in the human brain when the plasma glucose level is well above the Michaelis-Menten constant for half-maximal transport, K(t). In experiments wh...

  12. Complex Reaction Kinetics in Chemistry: A Unified Picture Suggested by Mechanics in Physics

    Directory of Open Access Journals (Sweden)

    Elena Agliari

    2018-01-01

    Full Text Available Complex biochemical pathways can be reduced to chains of elementary reactions, which can be described in terms of chemical kinetics. Among the elementary reactions so far extensively investigated, we recall the Michaelis-Menten and the Hill positive-cooperative kinetics, which apply to molecular binding and are characterized by the absence and the presence, respectively, of cooperative interactions between binding sites. However, there is evidence of reactions displaying a more complex pattern: these follow the positive-cooperative scenario at small substrate concentration, yet negative-cooperative effects emerge as the substrate concentration is increased. Here, we analyze the formal analogy between the mathematical backbone of (classical reaction kinetics in Chemistry and that of (classical mechanics in Physics. We first show that standard cooperative kinetics can be framed in terms of classical mechanics, where the emerging phenomenology can be obtained by applying the principle of least action of classical mechanics. Further, since the saturation function plays in Chemistry the same role played by velocity in Physics, we show that a relativistic scaffold naturally accounts for the kinetics of the above-mentioned complex reactions. The proposed formalism yields to a unique, consistent picture for cooperative-like reactions and to a stronger mathematical control.

  13. New insights into the catalytic mechanism of human glycine N-acyltransferase.

    Science.gov (United States)

    van der Sluis, Rencia; Ungerer, Vida; Nortje, Carla; A van Dijk, Alberdina; Erasmus, Elardus

    2017-11-01

    Even though the glycine conjugation pathway was one of the first metabolic pathways to be discovered, this pathway remains very poorly characterized. The bi-substrate kinetic parameters of a recombinant human glycine N-acyltransferase (GLYAT, E.C. 2.3.1.13) were determined using the traditional colorimetric method and a newly developed HPLC-ESI-MS/MS method. Previous studies analyzing the kinetic parameters of GLYAT, indicated a random Bi-Bi and/or ping-pong mechanism. In this study, the hippuric acid concentrations produced by the GLYAT enzyme reaction were analyzed using the allosteric sigmoidal enzyme kinetic module. Analyses of the initial rate (v) against substrate concentration plots, produced a sigmoidal curve (substrate activation) when the benzoyl-CoA concentrations was kept constant, whereas the plot with glycine concentrations kept constant, passed through a maximum (substrate inhibition). Thus, human GLYAT exhibits mechanistic kinetic cooperativity as described by the Ferdinand enzyme mechanism rather than the previously assumed Michaelis-Menten reaction mechanism. © 2017 Wiley Periodicals, Inc.

  14. The mechanism distinguishability problem in biochemical kinetics: the single-enzyme, single-substrate reaction as a case study.

    Science.gov (United States)

    Schnell, Santiago; Chappell, Michael J; Evans, Neil D; Roussel, Marc R

    2006-01-01

    A theoretical analysis of the distinguishability problem of two rival models of the single enzyme-single substrate reaction, the Michaelis-Menten and Henri mechanisms, is presented. We also outline a general approach for analysing the structural indistinguishability between two mechanisms. The approach involves constructing, if possible, a smooth mapping between the two candidate models. Evans et al. [N.D. Evans, M.J. Chappell, M.J. Chapman, K.R. Godfrey, Structural indistinguishability between uncontrolled (autonomous) nonlinear analytic systems, Automatica 40 (2004) 1947-1953] have shown that if, in addition, either of the mechanisms satisfies a particular criterion then such a transformation always exists when the models are indistinguishable from their experimentally observable outputs. The approach is applied to the single enzyme-single substrate reaction mechanism. In principle, mechanisms can be distinguished using this analysis, but we show that our ability to distinguish mechanistic models depends both on the precise measurements made, and on our knowledge of the system prior to performing the kinetics experiments.

  15. Kinetics and mechanism of oxidation of aliphatic alcohols by ...

    Indian Academy of Sciences (India)

    TBATB) in aqueous acetic acid leads to the formation of the corresponding aldehydes. The reaction is first order with respect to TBATB. Michaelis-Menten type kinetics is observed with respect to alcohols. The reaction failed to induce the ...

  16. Competition between roots and microorganisms for nitrogen: mechanisms and ecological relevance

    Science.gov (United States)

    Kuzyakov, Yakov; Xu, Xingliang

    2014-05-01

    Demand of all living organisms on the same nutrients forms the basis for interspecific competition between plants and microorganisms in soils. This competition is especially strong in the rhizosphere. To evaluate competitive and mutualistic interactions between plants and microorganisms and to analyse ecological consequences of these interactions, we analysed 424 data pairs from 41 15N-labelling studies that investigated 15N redistribution between roots and microorganisms. Calculated Michaelis-Menten kinetics based on Km (Michaelis constant) and Vmax (maximum uptake capacity) values from 77 studies on the uptake of nitrate, ammonia, and amino acids by roots and microorganisms clearly showed that, shortly after nitrogen (N) mobilization from soil organic matter and litter, microorganisms take up most N. Lower Km values of microorganisms suggest that they are especially efficient at low N concentrations, but can also acquire more N at higher N concentrations (Vmax) compared with roots. Because of the unidirectional flow of nutrients from soil to roots, plants are the winners for N acquisition in the long run. Therefore, despite strong competition between roots and microorganisms for N, a temporal niche differentiation reflecting their generation times leads to mutualistic relationships in the rhizosphere. This temporal niche differentiation is highly relevant ecologically because it: protects ecosystems from N losses by leaching during periods of slow or no root uptake; continuously provides roots with available N according to plant demand; and contributes to the evolutionary development of mutualistic interactions between roots and microorganisms.

  17. Mechanical property characterization of polymeric composites reinforced by continuous microfibers

    Science.gov (United States)

    Zubayar, Ali

    Innumerable experimental works have been conducted to study the effect of polymerization on the potential properties of the composites. Experimental techniques are employed to understand the effects of various fibers, their volume fractions and matrix properties in polymer composites. However, these experiments require fabrication of various composites which are time consuming and cost prohibitive. Advances in computational micromechanics allow us to study the various polymer based composites by using finite element simulations. The mechanical properties of continuous fiber composite strands are directional. In traditional continuous fiber laminated composites, all fibers lie in the same plane. This provides very desirable increases in the in-plane mechanical properties, but little in the transverse mechanical properties. The effect of different fiber/matrix combinations with various orientations is also available. Overall mechanical properties of different micro continuous fiber reinforced composites with orthogonal geometry are still unavailable in the contemporary research field. In this research, the mechanical properties of advanced polymeric composite reinforced by continuous micro fiber will be characterized based on analytical investigation and FE computational modeling. Initially, we have chosen IM7/PEEK, Carbon Fiber/Nylon 6, and Carbon Fiber/Epoxy as three different case study materials for analysis. To obtain the equivalent properties of the micro-hetero structures, a concept of micro-scale representative volume elements (RVEs) is introduced. Five types of micro scale RVEs (3 square and 2 hexagonal) containing a continuous micro fiber in the polymer matrix were designed. Uniaxial tensile, lateral expansion and transverse shear tests on each RVE were designed and conducted by the finite element computer modeling software ANSYS. The formulae based on elasticity theory were derived for extracting the equivalent mechanical properties (Young's moduli, shear

  18. Thymidine kinase 2 enzyme kinetics elucidate the mechanism of thymidine-induced mitochondrial DNA depletion.

    Science.gov (United States)

    Sun, Ren; Wang, Liya

    2014-10-07

    Mitochondrial thymidine kinase 2 (TK2) is a nuclear gene-encoded protein, synthesized in the cytosol and subsequently translocated into the mitochondrial matrix, where it catalyzes the phosphorylation of thymidine (dT) and deoxycytidine (dC). The kinetics of dT phosphorylation exhibits negative cooperativity, but dC phosphorylation follows hyperbolic Michaelis-Menten kinetics. The two substrates compete with each other in that dT is a competitive inhibitor of dC phosphorylation, while dC acts as a noncompetitive inhibitor of dT phosphorylation. In addition, TK2 is feedback inhibited by dTTP and dCTP. TK2 also phosphorylates a number of pyrimidine nucleoside analogues used in antiviral and anticancer therapy and thus plays an important role in mitochondrial toxicities caused by nucleoside analogues. Deficiency in TK2 activity due to genetic alterations causes devastating mitochondrial diseases, which are characterized by mitochondrial DNA (mtDNA) depletion or multiple deletions in the affected tissues. Severe TK2 deficiency is associated with early-onset fatal mitochondrial DNA depletion syndrome, while less severe deficiencies result in late-onset phenotypes. In this review, studies of the enzyme kinetic behavior of TK2 enzyme variants are used to explain the mechanism of mtDNA depletion caused by TK2 mutations, thymidine overload due to thymidine phosphorylase deficiency, and mitochondrial toxicity caused by antiviral thymidine analogues.

  19. Subcellular distribution and uptake mechanism of di-n-butyl phthalate in roots of pumpkin (Cucurbita moschata) seedlings.

    Science.gov (United States)

    Lin, Qingqi; Yang, Xiuhong; Huang, Xiongfei; Wang, Shizhong; Chao, Yuanqing; Qiu, Rongliang

    2016-01-01

    Phthalate acid esters (PAEs) are of particular concern due to their potential environmental risk to human and nonhuman organisms. Although uptake of PAEs by plants has been reported by several researchers, information about the intracellular distribution and uptake mechanisms of PAEs is still lacking. In this study, a series of hydroponic experiments using intact pumpkin (Cucurbita moschata) seedlings was conducted to investigate how di-n-butyl phthalate (DnBP), one of the most frequently identified PAEs in the environment, enters and is distributed in roots. DnBP was transported into subcellular tissues rapidly in the initial uptake period (<12 h). More than 80% of DnBP was detected in the cell walls and organelles, which suggests that DnBP is primarily accumulated in these two fractions due to their high affinity to DnBP. The kinetics of DnBP uptake were fitted well with the Michaelis-Menten equation, suggesting that a carrier-mediated process was involved. The application of 2,4-dinitrophenol and sodium vanadate reduced the uptake of DnBP by 37 and 26%, respectively, while aquaporin inhibitors, silver and glycerol, had no effect on DnBP uptake. These data demonstrated that the uptake of DnBP included a carrier-mediated and energy-dependent process without the participation of aquaporins.

  20. Enzymatic oxidation of rutin by horseradish peroxidase: kinetic mechanism and identification of a dimeric product by LC-Orbitrap mass spectrometry.

    Science.gov (United States)

    Savic, Sasa; Vojinovic, Katarina; Milenkovic, Sanja; Smelcerovic, Andrija; Lamshoeft, Marc; Petronijevic, Zivomir

    2013-12-15

    Flavonoid oxidation is important issue in food processing and quality. The kinetic mechanism of enzymatic oxidation of rutin by horseradish peroxidase (HRP) was studied. Rutin oxidation reaction was followed by recording of spectral changes over the time at 360 nm. The studied oxidation is mostly enzymatic and less part non-enzymatic. The reaction with HRP has a higher rate compared with the reaction without of HRP, whereby is part of non-enzymatic reaction about 10% of the total reaction. Kinetic parameters were determined from graphics of linear Michaelis-Menten equation, and it was found that investigated reactions of rutin oxidation by HRP take place in a ping-pong kinetic mechanism. High resolution HPLC-MS analysis of the mixture of oxidized products of rutin revealed the presence of rutin dimer. Because of widely distribution of rutin as well as presence of peroxidases and hydrogen peroxide in fresh foods identification of this enzymatic modification product can be beneficial for foods quality and safety. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Bohmian mechanics, open quantum systems and continuous measurements

    CERN Document Server

    Nassar, Antonio B

    2017-01-01

    This book shows how Bohmian mechanics overcomes the need for a measurement postulate involving wave function collapse. The measuring process plays a very important role in quantum mechanics. It has been widely analyzed within the Copenhagen approach through the Born and von Neumann postulates, with later extension due to Lüders. In contrast, much less effort has been invested in the measurement theory within the Bohmian mechanics framework. The continuous measurement (sharp and fuzzy, or strong and weak) problem is considered here in this framework. The authors begin by generalizing the so-called Mensky approach, which is based on restricted path integral through quantum corridors. The measuring system is then considered to be an open quantum system following a stochastic Schrödinger equation. Quantum stochastic trajectories (in the Bohmian sense) and their role in basic quantum processes are discussed in detail. The decoherence process is thereby described in terms of classical trajectories issuing from th...

  2. Distinct timing mechanisms produce discrete and continuous movements.

    Directory of Open Access Journals (Sweden)

    Raoul Huys

    2008-04-01

    Full Text Available The differentiation of discrete and continuous movement is one of the pillars of motor behavior classification. Discrete movements have a definite beginning and end, whereas continuous movements do not have such discriminable end points. In the past decade there has been vigorous debate whether this classification implies different control processes. This debate up until the present has been empirically based. Here, we present an unambiguous non-empirical classification based on theorems in dynamical system theory that sets discrete and continuous movements apart. Through computational simulations of representative modes of each class and topological analysis of the flow in state space, we show that distinct control mechanisms underwrite discrete and fast rhythmic movements. In particular, we demonstrate that discrete movements require a time keeper while fast rhythmic movements do not. We validate our computational findings experimentally using a behavioral paradigm in which human participants performed finger flexion-extension movements at various movement paces and under different instructions. Our results demonstrate that the human motor system employs different timing control mechanisms (presumably via differential recruitment of neural subsystems to accomplish varying behavioral functions such as speed constraints.

  3. Enzyme-like catalysis via ternary complex mechanism: alkoxy-bridged dinuclear cobalt complex mediates chemoselective O-esterification over N-amidation.

    Science.gov (United States)

    Hayashi, Yukiko; Santoro, Stefano; Azuma, Yuki; Himo, Fahmi; Ohshima, Takashi; Mashima, Kazushi

    2013-04-24

    Hydroxy group-selective acylation in the presence of more nucleophilic amines was achieved using acetates of first-row late transition metals, such as Mn, Fe, Co, Cu, and Zn. Among them, cobalt(II) acetate was the best catalyst in terms of reactivity and selectivity. The combination of an octanuclear cobalt carboxylate cluster [Co4(OCOR)6O]2 (2a: R = CF3, 2b: R = CH3, 2c: R = (t)Bu) with nitrogen-containing ligands, such as 2,2'-bipyridine, provided an efficient catalytic system for transesterification, in which an alkoxide-bridged dinuclear complex, Co2(OCO(t)Bu)2(bpy)2(μ2-OCH2-C6H4-4-CH3)2 (10), was successfully isolated as a key intermediate. Kinetic studies and density functional theory calculations revealed Michaelis-Menten behavior of the complex 10 through an ordered ternary complex mechanism similar to dinuclear metallo-enzymes, suggesting the formation of alkoxides followed by coordination of the ester.

  4. Flux continuity and probability conservation in complexified Bohmian mechanics

    International Nuclear Information System (INIS)

    Poirier, Bill

    2008-01-01

    Recent years have seen increased interest in complexified Bohmian mechanical trajectory calculations for quantum systems as both a pedagogical and computational tool. In the latter context, it is essential that trajectories satisfy probability conservation to ensure they are always guided to where they are most needed. We consider probability conservation for complexified Bohmian trajectories. The analysis relies on time-reversal symmetry considerations, leading to a generalized expression for the conjugation of wave functions of complexified variables. This in turn enables meaningful discussion of complexified flux continuity, which turns out not to be satisfied in general, though a related property is found to be true. The main conclusion, though, is that even under a weak interpretation, probability is not conserved along complex Bohmian trajectories

  5. Competition between roots and microorganisms for nitrogen: mechanisms and ecological relevance.

    Science.gov (United States)

    Kuzyakov, Yakov; Xu, Xingliang

    2013-05-01

    Demand of all living organisms on the same nutrients forms the basis for interspecific competition between plants and microorganisms in soils. This competition is especially strong in the rhizosphere. To evaluate competitive and mutualistic interactions between plants and microorganisms and to analyse ecological consequences of these interactions, we analysed 424 data pairs from 41 (15)N-labelling studies that investigated (15)N redistribution between roots and microorganisms. Calculated Michaelis-Menten kinetics based on K(m) (Michaelis constant) and V(max) (maximum uptake capacity) values from 77 studies on the uptake of nitrate, ammonia, and amino acids by roots and microorganisms clearly showed that, shortly after nitrogen (N) mobilization from soil organic matter and litter, microorganisms take up most N. Lower K(m) values of microorganisms suggest that they are especially efficient at low N concentrations, but can also acquire more N at higher N concentrations (V(max)) compared with roots. Because of the unidirectional flow of nutrients from soil to roots, plants are the winners for N acquisition in the long run. Therefore, despite strong competition between roots and microorganisms for N, a temporal niche differentiation reflecting their generation times leads to mutualistic relationships in the rhizosphere. This temporal niche differentiation is highly relevant ecologically because it: protects ecosystems from N losses by leaching during periods of slow or no root uptake; continuously provides roots with available N according to plant demand; and contributes to the evolutionary development of mutualistic interactions between roots and microorganisms. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  6. Function of mechanically lengthened jejunum after restoration into continuity.

    Science.gov (United States)

    Sullins, Veronica F; Wagner, Justin P; Walthers, Christopher M; Chiang, Elvin K; Lee, Steven L; Wu, Benjamin M; Dunn, James C Y

    2014-06-01

    Distraction enterogenesis is a potential treatment for patients with short bowel syndrome. We previously demonstrated successful lengthening of jejunum using a degradable spring device in rats. Absorptive function of the lengthened jejunum after restoration into intestinal continuity needs to be determined. Encapsulated polycaprolactone springs were placed into isolated jejunal segments in rats for four weeks. Lengthened segments of jejunum were subsequently restored into intestinal continuity. Absorption studies were performed by placing a mixture of a non-absorbable substrate and glucose into the lumen of the restored jejunum. Restored jejunal segments demonstrated visible peristalsis at specimen retrieval. Compared to normal jejunal controls, restored segments demonstrated equal water absorption and greater glucose absorption. Restored segments had thicker smooth muscle, increased villus height, increased crypt depth, and decreased sucrase activity compared to normal jejunum. The density of enteric ganglia increased after restoration to near normal levels in the submucosa and to normal levels in the myenteric plexus. Jejunum lengthened with a degradable device demonstrates peristaltic and enzymatic activity as well as glucose and water absorption after restoration into intestinal continuity. Our findings further demonstrate the therapeutic potential of a degradable device. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Inhibition of basolateral branchial Na{sup +}/K{sup +}-ATPase may be the key mechanism for silver toxicity in fish

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, E.; Hogstrand, C. [Univ. of Kentucky, Lexington, KY (United States). T.H. Morgan School of Biological Science

    1995-12-31

    Recent studies of freshwater fish have indicated that the mechanism of silver toxicity may lie in the ability of the metal to compromise bronchial transport of Na{sup +} and Cl (Wood et al, 1994). As part of a study, investigating the physiological mechanisms of silver toxicity to marine fish, the effect of Ag{sup +} on Na{sup +}/K{sup +}-ATPase in isolated basolateral membranes (BLM) from gills of sea-water acclimated rainbow trout was analyzed. Silver inhibition of purified dog kidney Na{sup +}/K{sup +}-ATPase was studied in a pilot experiment and the results from this experiment were compared to those obtained for rainbow trout BLMS. Michaelis-Menten kinetics of Na{sup +}/K{sup +}-ATPase activity was performed during control conditions by varying the concentrations of Na+ and K+ in the assay medium while keeping the total salt concentration constant. Inhibition of Na{sup +}/K{sup +}-ATPase activities was investigated by adding 1 nM--1 {micro}M of Ag{sup +} to the medium. Assay conditions were optimized separately for dog and rainbow trout Na{sup +}/K{sup +}-ATPase. Results from both series indicate effect of Ag{sup +} at a concentration as low as 1 nM escalating to complete quenching at a Ag{sup +} activity of 1 {micro}M. These results suggest the key mechanism of silver toxicity in marine fish involves blockage of the Na{sup +}/K{sup +}-ATPase activity in the gill epithelium.

  8. "THE EVALUATION OF THE POSSIBLE EFFECT OF POSITIVE END EXPIRATORY PRESSURE (PEEP ON PHARMACOKINETICS OF PHENYTOIN IN PATIENTS WITH ACUTE BRAIN INJURY UNDER MECHANICAL VENTILATION."

    Directory of Open Access Journals (Sweden)

    "Elham Hadidi

    2005-04-01

    Full Text Available Positive ventilation has shown to have an influence on pharmacokinetic and disposition of some drugs.Beacause phenytoin with a narrow therapautic range, is the most commonly used drug for prophylaxis and treatment of early seizures after acute brain injuries, in the present study the effect of short term PEEP (5-10 cm H2O for at least 8 hours on phenytoin serum concentration and pharmacokinetic parameters such as Vmax and clearance in brain injured patients under mechanical ventilation was examined. Ten patients with moderate to severe acute brain injury who were placed on mechanical ventilation with an initial PEEP level of 0-5 cm H2O were included in the study. Patients received phenytoin loading dose of 15 mg/kg followed by a maintenance daily dose of 3-7 mg/kg initiated within 12 hours of loading dose. Sampels were taken on two different occasions before and after PEEP elevation. Total phenytoin serum concentrations were determined by HPLC method. A time invarient Michaelis-Menten pharmacokinetic model was used to calculate Vmax and clearance for each patient.Derrived variables were calculated as follows: Vmax, 3.5-6.8 and 3.7-8.2 mg/kg/day; Clearance, 0.1-0.7 and 0.1-1.2 l/kg/day (before and after PEEP elevation, respectively. Our data have shown a wide range of variability (2.6-32.5 mg/l in phenytoin serum concentrations. There were no statistically significant differences in the measured total concentrations (p=0.721 and calculated Vmax and clearance (p=0.285before and after PEEP elevation. Administration of fluid and inotropic agents, limitation in application of higher levels of PEEP and drug interactions, shall be considered as possible explanations for these findings.

  9. DICER-ARGONAUTE2 complex in continuous fluorogenic assays of RNA interference enzymes.

    Directory of Open Access Journals (Sweden)

    Mark A Bernard

    Full Text Available Mechanistic studies of RNA processing in the RNA-Induced Silencing Complex (RISC have been hindered by lack of methods for continuous monitoring of enzymatic activity. "Quencherless" fluorogenic substrates of RNAi enzymes enable continuous monitoring of enzymatic reactions for detailed kinetics studies. Recombinant RISC enzymes cleave the fluorogenic substrates targeting human thymidylate synthase (TYMS and hypoxia-inducible factor 1-α subunit (HIF1A. Using fluorogenic dsRNA DICER substrates and fluorogenic siRNA, DICER+ARGONAUTE2 mixtures exhibit synergistic enzymatic activity relative to either enzyme alone, and addition of TRBP does not enhance the apparent activity. Titration of AGO2 and DICER in enzyme assays suggests that AGO2 and DICER form a functional high-affinity complex in equimolar ratio. DICER and DICER+AGO2 exhibit Michaelis-Menten kinetics with DICER substrates. However, AGO2 cannot process the fluorogenic siRNA without DICER enzyme, suggesting that AGO2 cannot self-load siRNA into its active site. The DICER+AGO2 combination processes the fluorogenic siRNA substrate (Km=74 nM with substrate inhibition kinetics (Ki=105 nM, demonstrating experimentally that siRNA binds two different sites that affect Dicing and AGO2-loading reactions in RISC. This result suggests that siRNA (product of DICER bound in the active site of DICER may undergo direct transfer (as AGO2 substrate to the active site of AGO2 in the DICER+AGO2 complex. Competitive substrate assays indicate that DICER+AGO2 cleavage of fluorogenic siRNA is specific, since unlabeled siRNA and DICER substrates serve as competing substrates that cause a concentration-dependent decrease in fluorescent rates. Competitive substrate assays of a series of DICER substrates in vitro were correlated with cell-based assays of HIF1A mRNA knockdown (log-log slope=0.29, suggesting that improved DICER substrate designs with 10-fold greater processing by the DICER+AGO2 complex can provide a

  10. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Kinetics and mechanism of oxidation of formic and oxalic acids by quinolinium fluorochromate (QFC) have been studied in dimethylsulphoxide. The main product of oxidation is carbon dioxide. The reaction is first-order with respect to QFC. Michaelis-Menten type of kinetics were observed with respect to the reductants.

  11. Elimination of intermediate species in multiscale stochastic reaction networks

    DEFF Research Database (Denmark)

    Cappelletti, Daniele; Wiuf, Carsten

    2016-01-01

    such as the substrate-enzyme complex in the Michaelis-Menten mechanism. Such species are virtually in all real-world networks, they are typically short-lived, degraded at a fast rate and hard to observe experimentally. We provide conditions under which the Markov process of a multiscale reaction network...

  12. Picolinic acid promoted oxidative decarboxylation of ...

    African Journals Online (AJOL)

    The kinetics and mechanism of picolinic acid promoted reaction of phenylsulfinylacetic acid (PSAA) with Cr(VI) was carried out in aqueous acetonitrile medium under pseudo first order conditions. The reaction follows Michaelis-Menten type of kinetics with respect to PSAA. The catalytic activity by picolinic acid can be ...

  13. Primary Structure and Mechanical Properties of AlSi2 Alloy Continuous Ingots

    Directory of Open Access Journals (Sweden)

    Wróbel T.

    2017-06-01

    Full Text Available The paper presents the research results of horizontal continuous casting of ingots of aluminium alloy containing 2% wt. silicon (AlSi2. Together with the casting velocity (velocity of ingot movement we considered the influence of electromagnetic stirring in the area of the continuous casting mould on refinement of the ingot’s primary structure and their selected mechanical properties, i.e. tensile strength, yield strength, hardness and elongation. The effect of primary structure refinement and mechanical properties obtained by electromagnetic stirring was compared with refinement obtained by using traditional inoculation, which consists in introducing additives, i.e. Ti, B and Sr, to the metal bath. On the basis of the obtained results we confirmed that inoculation done by electromagnetic stirring in the range of the continuous casting mould guarantees improved mechanical properties and also decreases the negative influence of casting velocity, thus increasing the structure of AlSi2 continuous ingots.

  14. Routes to chaos in continuous mechanical systems: Part 2. Modelling transitions from regular to chaotic dynamics

    International Nuclear Information System (INIS)

    Krysko, A.V.; Awrejcewicz, J.; Papkova, I.V.; Krysko, V.A.

    2012-01-01

    In second part of the paper both classical and novel scenarios of transition from regular to chaotic dynamics of dissipative continuous mechanical systems are studied. A detailed analysis allowed us to detect the already known classical scenarios of transition from periodic to chaotic dynamics, and in particular the Feigenbaum scenario. The Feigenbaum constant was computed for all continuous mechanical objects studied in the first part of the paper. In addition, we illustrate and discuss different and novel scenarios of transition of the analysed systems from regular to chaotic dynamics, and we show that the type of scenario depends essentially on excitation parameters.

  15. Curaua and eucalyptus nanofibers films by continuous casting: Mechanical and thermal properties.

    Science.gov (United States)

    Claro, Pedro Ivo Cunha; Corrêa, Ana Carolina; de Campos, Adriana; Rodrigues, Vanessa Bolzan; Luchesi, Bruno Ribeiro; Silva, Luiz Eduardo; Mattoso, Luiz Henrique Capparelli; Marconcini, José Manoel

    2018-02-01

    A wide variety of new green materials such as curaua leaf fibers (CLFs) has potential applications in nanotechnology. This study aims to investigate the thermomechanical properties and morphological structure of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) films obtained by continuous casting. The CNCs were obtained by acid hydrolysis and CNFs by mechanical shearing from bleached CLFs and eucalyptus pulp. The morphology after continuous casting resulted in oriented nanofibers, and as a consequence there was mechanical anisotropy. CNCs films showed the greatest values of tensile strength (36±4MPa) and the more effective fibrillation provided better mechanical strength of eucalyptus CNFs films than curaua CNFs films. Sulfur groups and mechanical shear degradation affected the stability of CNCs and CNFs films, respectively. Thus, the type of nanostructure, the way they interact to each other, the cellulose source and the process interfere significantly on the properties of the films. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Mechanical properties of permeable materials with an organized structure on the base of continuous metal fibers

    International Nuclear Information System (INIS)

    Karpinos, D.M.; Rutkovskij, A.E.; Zorin, V.A.; Ivanchuk, A.A.

    1979-01-01

    The mechanical properties were studied for permeable fibrous materials with an organized structure on the base of continuous metal fibers (from Kh18N9T steel) subjected to preliminary reprocessing volumetric net half-finished products. The effect of geometrical parameters of the net half-finished products and of their orientation in packing are shown to affect the mechanical properties within a wide range of porosities

  17. FEATURES OF LONG-TERM MECHANICAL CIRCULATORY SUPPORT WITH CONTINUOUS-FLOW PUMP

    Directory of Open Access Journals (Sweden)

    G. P. Itkin

    2012-01-01

    Full Text Available In a review of the comparative analysis of methods and tools for long-term mechanical circulatory support with continuous flow and pulsatile flow implantable pumps. Particular attention is paid to the choice of the optimal modes of the operation of pumps based on the physical principles of the interaction between a the steady flow of blood to the pulsatile mechanics of the heart chambers. 

  18. Improvement of the mechanical and frictional properties of steels by continuous and pulsed ion irradiation

    International Nuclear Information System (INIS)

    Romanov, I.G.

    1992-01-01

    Effect of continuous and powerful pulsed ion beams (PIB) on structural, mechanical, tribological properties and surface morphology of steels were investigated. The results obtained demonstrate the significant influence of ion irradiation type on microhardness, friction coefficient, wear resistance and surface roughness characteristics. Friction coefficient variation in irradiated steels is interpreted within the framework of an adhesion-deformation model

  19. Design of Electro-Mechanical Dual-Acting Pulley Continuously Variable Transmission

    Directory of Open Access Journals (Sweden)

    K.B. Tawi

    2015-06-01

    Full Text Available Pulley-based continuously variable transmission (CVT with a metal pushing V-belt is fast becoming the preferred choice for global carmakers due to its potential particularly in terms of fuel efficiency thanks to its continuous and wide ratio range. Nevertheless, the existing CVTs still face the issues of high power consumption from the engine because of the application of an electro-hydro-mechanical (EHM actuation system for its ratio changing process and clamping force mechanism. To address this issue, researchers from Universiti Teknologi Malaysia have successfully developed the prototype of an electro-mechanical dual-acting pulley continuously variable transmission (EMDAP CVT for automotive applications. The prototype of EMDAP CVT is developed for a maximum input torque of 160 Nm with the application of a metal pushing V-belt. The results from the testing prove that the prototype can vary its ratio from 2.8 to 0.6 and no continuous power is required to maintain a constant CVT ratio. These results suggest that the prototype is workable and future testing in a real car is possible.

  20. Graphene as a Prototypical Model for Two-Dimensional Continuous Mechanics

    Directory of Open Access Journals (Sweden)

    Philippe Lambin

    2017-08-01

    Full Text Available This paper reviews a few problems where continuous-medium theory specialized to two-dimensional media provides a qualitatively correct picture of the mechanical behavior of graphene. A critical analysis of the parameters involved is given. Among other results, a simple mathematical description of a folded graphene sheet is proposed. It is also shown how the graphene–graphene adhesion interaction is related to the cleavage energy of graphite and its C 33 bulk elastic constant.

  1. A long-lived lunar dynamo driven by continuous mechanical stirring.

    Science.gov (United States)

    Dwyer, C A; Stevenson, D J; Nimmo, F

    2011-11-09

    Lunar rocks contain a record of an ancient magnetic field that seems to have persisted for more than 400 million years and which has been attributed to a lunar dynamo. Models of conventional dynamos driven by thermal or compositional convection have had difficulty reproducing the existence and apparently long duration of the lunar dynamo. Here we investigate an alternative mechanism of dynamo generation: continuous mechanical stirring arising from the differential motion, due to Earth-driven precession of the lunar spin axis, between the solid silicate mantle and the liquid core beneath. We show that the fluid motions and the power required to drive a dynamo operating continuously for more than one billion years and generating a magnetic field that had an intensity of more than one microtesla 4.2 billion years ago are readily obtained by mechanical stirring. The magnetic field is predicted to decrease with time and to shut off naturally when the Moon recedes far enough from Earth that the dissipated power is insufficient to drive a dynamo; in our nominal model, this occurred at about 48 Earth radii (2.7 billion years ago). Thus, lunar palaeomagnetic measurements may be able to constrain the poorly known early orbital evolution of the Moon. This mechanism may also be applicable to dynamos in other bodies, such as large asteroids.

  2. Continuous positive airway pressure and conventional mechanical ventilation in the treatment of meconium aspiration syndrome.

    Science.gov (United States)

    Goldsmith, J P

    2008-12-01

    Meconium aspiration syndrome (MAS) is a complex syndrome that ranges in severity from mild respiratory distress to severe respiratory failure, persistent pulmonary hypertension of the newborn and sometimes death. Understanding of the syndrome's complicated pathophysiology will help determine the appropriate treatment strategy, including the use of continuous positive airway pressure (CPAP), conventional mechanical ventilation (CMV) and other therapies. Approximately 30 to 50% of infants diagnosed with MAS will require CPAP or mechanical ventilation. The optimum modes of ventilation for MAS are not known. Very few studies have been conducted to determine 'best' ventilatory strategies. Despite the introduction, over the last two decades, of innovative ventilatory treatments for this disease (for example, surfactant, high-frequency ventilation, inhaled nitric oxide, extracorporeal membrane oxygenation), the majority of infants can be successfully managed with CPAP or mechanical ventilation alone.

  3. Thermo-mechanical simulation and parameters optimization for beam blank continuous casting

    International Nuclear Information System (INIS)

    Chen, W.; Zhang, Y.Z.; Zhang, C.J.; Zhu, L.G.; Lu, W.G.; Wang, B.X.; Ma, J.H.

    2009-01-01

    The objective of this work is to optimize the process parameters of beam blank continuous casting in order to ensure high quality and productivity. A transient thermo-mechanical finite element model is developed to compute the temperature and stress profile in beam blank continuous casting. By comparing the calculated data with the metallurgical constraints, the key factors causing defects of beam blank can be found out. Then based on the subproblem approximation method, an optimization program is developed to search out the optimum cooling parameters. Those optimum parameters can make it possible to run the caster at its maximum productivity, minimum cost and to reduce the defects. Now, online verifying of this optimization project has been put in practice, which can prove that it is very useful to control the actual production

  4. Continuous three dimensional analysis of running mechanics during a marathon by means of inertial magnetic measurement units to objectify changes in running mechanics

    NARCIS (Netherlands)

    Reenalda, Jasper; Maartens, Erik; Maartens, Erik; Homan, Lotte; Buurke, Jaap

    2016-01-01

    Recent developments in wearable and wireless sensor technology allow for a continuous three dimensional analysis of running mechanics in the sport specific setting. The present study is the first to demonstrate the possibility of analyzing three dimensional (3D) running mechanics continuously, by

  5. Canceling effect: a natural mechanism to reduce the effects of global warming

    Science.gov (United States)

    Razavi, Bahar S.; Blagodatskaya, Evgenia; kuzyakov, Yakov

    2016-04-01

    , and incorporated into Earth system models to improve the predictions at regional and global levels. Key words: carbon cycle, Michaelis-Menten kinetics, Arrhenius function, soil enzymes, temperature sensitivity, canceling effect, activation energy.

  6. A new system for continuous and remote monitoring of patients receiving home mechanical ventilation.

    Science.gov (United States)

    Battista, L

    2016-09-01

    Home mechanical ventilation is the treatment of patients with respiratory failure or insufficiency by means of a mechanical ventilator at a patient's home. In order to allow remote patient monitoring, several tele-monitoring systems have been introduced in the last few years. However, most of them usually do not allow real-time services, as they have their own proprietary communication protocol implemented and some ventilation parameters are not always measured. Moreover, they monitor only some breaths during the whole day, despite the fact that a patient's respiratory state may change continuously during the day. In order to reduce the above drawbacks, this work reports the development of a novel remote monitoring system for long-term, home-based ventilation therapy; the proposed system allows for continuous monitoring of the main physical quantities involved during home-care ventilation (e.g., differential pressure, volume, and air flow rate) and is developed in order to allow observations of different remote therapy units located in different places of a city, region, or country. The developed remote patient monitoring system is able to detect various clinical events (e.g., events of tube disconnection and sleep apnea events) and has been successfully tested by means of experimental tests carried out with pulmonary ventilators typically used to support sick patients.

  7. Ion pump as Brownian motor: theory of electroconformational coupling and proof of ratchet mechanism for Na,K-ATPase action

    Science.gov (United States)

    Tsong, Tian Yow; Chang, Cheng-Hung

    2003-04-01

    This article reviews some concepts of the Brownian Ratchet which are relevant to our discussion of mechanisms of action of Na,K-ATPase, a universal ion pump and an elemental motor protein of the biological cell. Under wide ranges of ionic compositions it can hydrolyze an ATP and use the γ-phosphorous bond energy of ATP to pump 3 Na + out of, and 2 K + into the cell, both being uphill transport. During the ATP-dependent pump cycle, the enzyme oscillates between E1 and E2 states. Our experiment replaces ATP with externally applied electric field of various waveforms, amplitudes, and frequencies. The field enforced-oscillation, or fluctuation of E1 and E2 states enables the enzyme to harvest energy from the applied field and convert it to the chemical gradient energy of cations. A theory of electroconformational coupling (TEC), which embodies all the essential features of the Brownian Ratchet, successfully simulates these experimental results. Our analysis based on a four-state TEC model indicates that the equilibrium and the rate constants of the transport system define the frequency and the amplitude of the field for the optimal activation. Waveform, frequency, and amplitude are three elements of signal. Thus, electric signal of the ion pump is found by TEC analysis of the experimental data. Electric noise (white) superimposed on an electric signal changes the pump efficiency and produces effects similar to the stochastic resonance reported in other biological systems. The TEC concept is compared with the most commonly used Michaelis-Menten enzyme mechanism (MME) for similarities and differences. Both MME and TEC are catalytic wheels, which recycle the catalyst in each turnover. However, a MME can only catalyze reaction of descending free energy while a TEC enzyme can catalyze reaction of ascending free energy by harvesting needed energy from an off-equilibrium electric noise. The TEC mechanism is shown to be applicable to other biological motors and engines, as

  8. Prolonged lateral steep position impairs respiratory mechanics during continuous lateral rotation therapy in respiratory failure.

    Science.gov (United States)

    Schellongowski, Peter; Losert, Heidrun; Locker, Gottfried J; Laczika, Klaus; Frass, Michael; Holzinger, Ulrike; Bojic, Andja; Staudinger, Thomas

    2007-04-01

    To establish whether prolonged lateral steep position during continuous rotation therapy leads to improvement on pulmonary gas exchange, respiratory mechanics and hemodynamics. Prospective observational study. Intensive care unit of a university hospital. Twelve consecutive patients suffering from acute lung injury or adult respiratory distress syndrome undergoing continuous rotation therapy. Blood gas analysis, static lung compliance, blood pressure, cardiac index and pulmonary shunt fraction were measured in supine as well as in left and right lateral steep position at 62 degrees during continuous rotation therapy (phase I). Rotation was then stopped for 30 min with the patients in supine position, left and right lateral steep position, and the same measurements were performed every 10 min (phase II). Phase I and II revealed no significant changes in PaO(2)/FiO(2) ratio, mean arterial blood pressure, pulmonary shunt fraction, or cardiac index. Significantly lower static compliance was observed in lateral steep position than in supine position (pposition than in left and right lateral steep position (ppositioning impairs the compliance of the respiratory system. Prolonged lateral steep position does not lead to benefits with respect to oxygenation or hemodynamics. Individual response to the different positions is unpredictable. The pauses in "extreme" positions should be as short as possible.

  9. Virtual powers and virtual works in mechanics of micropolar continuous media

    International Nuclear Information System (INIS)

    Grossetie, J.C.

    1981-01-01

    The expression of virtual work and virtual powers of internal actions is established for a continuous medium where the actions are defined by fields of forces and moments. A basic formulation of the mechanical problem is thus obtained and can serve as the starting point for variational and quasi-variational formulations of these problems. This expression may be used in thermodynamic developments relating to research or constitutive laws of materials within the context of so-called hidden internal variable formulations. The principle of virtual works is given in general applied then to the classic case through a demonstration consistent with this principle and finally applied to the general case in which distributions of moments are included. The viewpoint adopted is that Euler-Cauchy. This expression will have to be accounted for in establishing thermodynamic relations regarding materials subjected to nuclear effects (irradiated materials)

  10. Reconciling semiclassical and Bohmian mechanics. III. Scattering states for continuous potentials

    International Nuclear Information System (INIS)

    Trahan, Corey; Poirier, Bill

    2006-01-01

    In a previous paper [B. Poirier, J. Chem. Phys. 121, 4501 (2004)] a unique bipolar decomposition Ψ=Ψ 1 +Ψ 2 was presented for stationary bound states Ψ of the one-dimensional Schroedinger equation, such that the components Ψ 1 and Ψ 2 approach their semiclassical WKB analogs in the large-action limit. The corresponding bipolar quantum trajectories, as defined in the usual Bohmian mechanical formulation, are classical-like and well behaved, even when Ψ has many nodes or is wildly oscillatory. A modification for discontinuous potential stationary scattering states was presented in a second, companion paper [C. Trahan and B. Poirier, J. Chem. Phys.124, 034115 (2006), previous paper], whose generalization for continuous potentials is given here. The result is an exact quantum scattering methodology using classical trajectories. For additional convenience in handling the tunneling case, a constant-velocity-trajectory version is also developed

  11. Continuous recrystallization and mechanical properties of a C45 steel after high pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, Mike; Fecht, Hans [Institute of Micro and Nanomaterials, University of Ulm, Ulm, Gemany (Germany); Institute of Nanotechnology, Karlsruhe Institut of Technology, Karlsruhe (Germany); Ning, Jiang Li; Ivanisenko, Yulia [Institute of Nanotechnology, Karlsruhe Institut of Technology, Karlsruhe (Germany); Hoermann, Ute [Central Facility for Electron Microscopy, University of Ulm, Ulm (Germany); Murashkin, Maxim [IPAM, Ufa State Aviation Technical University, Ufa (Russian Federation)

    2011-07-01

    An initial microstructure of C45 steel (Fe, 0.42-0.5% C, 0.5-0.8% Mn, <0.4% Si, <0.045% S, 0.045% P * All in wt%) was modified from ferritic-pearlitic to bainitic through heating at 900 C for 1 hour and quenching in a lead bath at 500 C for 30 min. The steel was processed by High Pressure Torsion (HPT) at room temperature for 3 and 5 rotations, which led to an ultrafine or nano-scale grained structure. Then the material was annealed at 400 C and 450 C for two hours, respectively. TEM observation showed that continuous recrystallization occurred during the annealing. The yield strength and elongation after annealing at 400 C and 450 C were 1277 MPa, 3%, and 1100 MPa, 11%, respectively. Compared with the mechanical properties before annealing, it was revealed that the continuous recrystallization during annealing led to an enhancement of the ductility, but without sacrificing much of the strength. Funding by the Deutsche Forschungsgemeinschaft and Russian Foundation for basic research is gratefully aknowledged.

  12. Noninvasive Positive Pressure Ventilation or Conventional Mechanical Ventilation for Neonatal Continuous Positive Airway Pressure Failure

    Directory of Open Access Journals (Sweden)

    Zohreh Badiee

    2014-01-01

    Full Text Available Background: The aim of this study was to assess the success rate of nasal intermittent positive pressure ventilation (NIPPV for treatment of continuous positive airway pressure (CPAP failure and prevention of conventional ventilation (CV in preterm neonates. Methods: Since November 2012 to April 2013, a total number of 55 consecutive newborns with gestational ages of 26-35 weeks who had CPAP failure were randomly assigned to one of the two groups. The NIPPV group received NIPPV with the initial peak inspiratory pressure (PIP of 16-20 cmH 2 O and frequency of 40-60 breaths/min. The CV group received PIP of 12-20 cmH 2 O and frequency of 40-60 breaths/min. Results: About 74% of newborns who received NIPPV for management of CPAP failure responded to NIPPV and did not need intubation and mechanical ventilation. Newborns with lower postnatal age at entry to the study and lower 5 min Apgar score more likely had NIPPV failure. In addition, treatment failure was higher in newborns who needed more frequent doses of surfactant. Duration of oxygen therapy was 9.28 days in CV group and 7.77 days in NIPPV group (P = 0.050. Length of hospital stay in CV group and NIPPV groups were 48.7 and 41.7 days, respectively (P = 0.097. Conclusions: NIPPV could decrease the need for intubation and mechanical ventilation in preterm infants with CPAP failure.

  13. Microscopic degradation mechanism of polyimide film caused by surface discharge under bipolar continuous square impulse voltage

    International Nuclear Information System (INIS)

    Luo Yang; Wu Guang-Ning; Liu Ji-Wu; Peng Jia; Gao Guo-Qiang; Zhu Guang-Ya; Wang Peng; Cao Kai-Jiang

    2014-01-01

    Polyimide (PI) film is an important type of insulating material used in inverter-fed motors. Partial discharge (PD) under a sequence of high-frequency square impulses is one of the key factors that lead to premature failures in insulation systems of inverter-fed motors. In order to explore the damage mechanism of PI film caused by discharge, an aging system of surface discharge under bipolar continuous square impulse voltage (BCSIV) is designed based on the ASTM 2275 01 standard and the electrical aging tests of PI film samples are performed above the partial discharge inception voltage (PDIV). The chemical bonds of PI polymer chains are analyzed through Fourier transform infrared spectroscopy (FTIR) and the dielectric properties of unaged and aged PI samples are investigated by LCR testers HIOKI 3532-50. Finally, the micro-morphology and micro-structure changes of PI film samples are observed through scanning electron microscopy (SEM). The results show that the physical and chemical effects of discharge cut off the chemical bonds of PI polymer chains. The fractures of ether bond (C—O—C) and imide ring (C—N—C) on the backbone of a PI polymer chain leads to the decrease of molecular weight, which results in the degradation of PI polymers and the generation of new chemical groups and materials, like carboxylic acid, ketone, aldehydes, etc. The variation of microscopic structure of PI polymers can change the orientation ability of polarizable units when the samples are under an AC electric field, which would cause the dielectric constant ε to increase and dielectric loss tan δ to decrease. The SEM images show that the degradation path of PI film is initiated from the surface and then gradually extends to the interior with continuous aging. The injection charge could result in the PI macromolecular chain degradation and increase the trap density in the PI polymer bulk. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  14. Self-similar pattern formation and continuous mechanics of self-similar systems

    Directory of Open Access Journals (Sweden)

    A. V. Dyskin

    2007-01-01

    Full Text Available In many cases, the critical state of systems that reached the threshold is characterised by self-similar pattern formation. We produce an example of pattern formation of this kind – formation of self-similar distribution of interacting fractures. Their formation starts with the crack growth due to the action of stress fluctuations. It is shown that even when the fluctuations have zero average the cracks generated by them could grow far beyond the scale of stress fluctuations. Further development of the fracture system is controlled by crack interaction leading to the emergence of self-similar crack distributions. As a result, the medium with fractures becomes discontinuous at any scale. We develop a continuum fractal mechanics to model its physical behaviour. We introduce a continuous sequence of continua of increasing scales covering this range of scales. The continuum of each scale is specified by the representative averaging volume elements of the corresponding size. These elements determine the resolution of the continuum. Each continuum hides the cracks of scales smaller than the volume element size while larger fractures are modelled explicitly. Using the developed formalism we investigate the stability of self-similar crack distributions with respect to crack growth and show that while the self-similar distribution of isotropically oriented cracks is stable, the distribution of parallel cracks is not. For the isotropically oriented cracks scaling of permeability is determined. For permeable materials (rocks with self-similar crack distributions permeability scales as cube of crack radius. This property could be used for detecting this specific mechanism of formation of self-similar crack distributions.

  15. Mechanism and prevention of edge over coating in continuous hot-dip galvanizing

    Energy Technology Data Exchange (ETDEWEB)

    Takeishi, Y.

    2000-11-01

    In order to clarify the mechanism of edge over coating (EOC) for continuous hot-dip galvanizing, a visualization test of the gas flow on strip and a cold model test to measure the profile of the coating thickness at the strip edge were carried out. Outward deflected gas flow was observed at the strip edge and EOC developed in the absence of gas wiping. With gas wiping, EOC developing below the wiping position is reduced by the impinging pressure of the gas wiping jet, and the film thickness becomes approximately uniform at the gas wiping position. However, upward of the gas wiping position. EOC increases again and the outward deflected gas flow on the strip edge sweeps the liquid film to the strip edge. EOC is considered to develop at the location where the dynamic pressure of the outward deflected gas flow balances with the surface tension. For the prevention of EOC, edge masking was devised and the effects which reduce EOC were measured in the cold model test and on a commercial line test. The edge mask which can be kept farther away from the strip edge is more effective for preventing EOC than the edge plates. The optimum dimension of the edge mask is 30mm in width and 75-100 mm in depth, and installing it at 4-10mm away from the strip edge is most effective. It was confirmed by the commercial line test that the edge mask can reduce EOC from 45% to less than 10%. (author)

  16. A Review of Continuing Professional Development (CPD of Training Competencies for Malaysian Mechanical Industries

    Directory of Open Access Journals (Sweden)

    Kasman Zeti

    2018-01-01

    Full Text Available The aim of this paper is to review issues in continuing professional development of vocational training to the mechanical industries. The spectacle of individuals entering the labour market without relevant qualifications is common in Malaysia. There are many who choose to work instead of pursuing further education after secondary school. In the labour market, these individuals are considered to be low-skilled workers because they had no training prior to employment. The role of employers in providing training and education to employees is vital in establishing career development of employees. Employers who contributed to their employees' training funds through Human Resources Development Council would provide opportunities to increase the skills of workers. Based on the Malaysia's Development Plan of Occupational Skill, the issues and challenges that have been identified in producing skilled workers in interpersonal and technical skills. This paper provided an opportunity to examine an enterprise-based approach to skill formation for workers with basic academic qualifications. It presents an alternative scenario to institution-based Technical and Vocational Education and Training (TVET, which many Malaysians are familiar with. A structured curriculum development of human resources learning needs according to the job profile of the typical individual and group work which will provide a clearer perspective on knowledge, competence and skill levels of employee behavior in performing tasks will be discussed. The biggest impact on this study is to produce high skill employees concerning customer satisfaction and increased organizational productivity towards high income nations.

  17. Cooperativity in CYP2E1 Metabolism of Acetaminophen and Styrene Mixtures

    OpenAIRE

    Hartman, Jessica H.; Letzig, Lynda G.; Robertsc, Dean W.; James, Laura P.; Fifer, E. Kim; Miller, Grover P.

    2015-01-01

    Risk assessment for exposure to mixtures of drugs and pollutants relies heavily on in vitro characterization of their bioactivation and/or metabolism individually and extrapolation to mixtures assuming no interaction. Herein, we demonstrated that in vitro CYP2E1 metabolic activation of acetaminophen and styrene mixtures could not be explained through the Michaelis-Menten mechanism or any models relying on that premise. As a baseline for mixture studies with styrene, steady-state analysis of a...

  18. The formation of continuous opinion dynamics based on a gambling mechanism and its sensitivity analysis

    Science.gov (United States)

    Zhu, Yueying; Alexandre Wang, Qiuping; Li, Wei; Cai, Xu

    2017-09-01

    The formation of continuous opinion dynamics is investigated based on a virtual gambling mechanism where agents fight for a limited resource. We propose a model with agents holding opinions between -1 and 1. Agents are segregated into two cliques according to the sign of their opinions. Local communication happens only when the opinion distance between corresponding agents is no larger than a pre-defined confidence threshold. Theoretical analysis regarding special cases provides a deep understanding of the roles of both the resource allocation parameter and confidence threshold in the formation of opinion dynamics. For a sparse network, the evolution of opinion dynamics is negligible in the region of low confidence threshold when the mindless agents are absent. Numerical results also imply that, in the presence of economic agents, high confidence threshold is required for apparent clustering of agents in opinion. Moreover, a consensus state is generated only when the following three conditions are satisfied simultaneously: mindless agents are absent, the resource is concentrated in one clique, and confidence threshold tends to a critical value(=1.25+2/ka ; k_a>8/3 , the average number of friends of individual agents). For fixed a confidence threshold and resource allocation parameter, the most chaotic steady state of the dynamics happens when the fraction of mindless agents is about 0.7. It is also demonstrated that economic agents are more likely to win at gambling, compared to mindless ones. Finally, the importance of three involved parameters in establishing the uncertainty of model response is quantified in terms of Latin hypercube sampling-based sensitivity analysis.

  19. Rock Mechanics Studies During Continuous Miner Bases Coal Pillar Extraction in Indian Coalfields

    Czech Academy of Sciences Publication Activity Database

    Ram, S.; Kumar, D.; Koníček, Petr; Singh, A. K.; Kumar, R.; Singh, A. Kr.; Singh, R.

    2015-01-01

    Roč. 111, April 2014-March 2015 (2015), s. 89-104 ISSN 0254-8003 Institutional support: RVO:68145535 Keywords : mining * mechanized depillaring scenario * rock mechanics Subject RIV: DH - Mining, incl. Coal Mining

  20. Mechanisms that contribute to the tendency to continue chemotherapy in patients with advanced cancer. Qualitative observations in the clinical setting.

    Science.gov (United States)

    Brom, Linda; Onwuteaka-Philipsen, Bregje D; Widdershoven, Guy A M; Pasman, H Roeline W

    2016-03-01

    The study aims to describe mechanisms that contribute to the tendency towards continuing chemotherapy in patients with advanced cancer. The study conducted qualitative observations of outpatient clinic visits of 28 patients with advanced cancer (glioblastoma and metastatic colorectal cancer). We uncovered four mechanisms in daily oncology practice that can contribute to the tendency towards continuing chemotherapy in patients with advanced cancer: (1) "presenting the full therapy sets the standard"--patients seemed to base their justification for continuing chemotherapy on the "standard" therapy with the maximum number of cycles as presented by the physician at the start of the treatment; (2) "focus on standard evaluation moments hampers evaluation of care goals"--whether or not to continue the treatment was mostly only considered at standard evaluation moments; (3) "opening question guides towards focus on symptoms"--most patients gave an update of their physical symptoms in answer to the opening question of "How are you doing?" Physicians consequently discussed how to deal with this at length, which often took up most of the visit; (4) "treatment is perceived as the only option"--patients mostly wanted to continue with chemotherapy because they felt that they had to try every available option the physician offered. Physicians also often seemed to focus on treatment as the only option. Discussing care goals more regularly with the patient, facilitated for instance by implementing early palliative care, might help counter the mechanisms and enable a more well-considered decision. This could be either stopping or continuing chemotherapy.

  1. Routes to chaos in continuous mechanical systems. Part 1: Mathematical models and solution methods

    International Nuclear Information System (INIS)

    Awrejcewicz, J.; Krysko, V.A.; Papkova, I.V.; Krysko, A.V.

    2012-01-01

    In this work chaotic dynamics of continuous mechanical systems such as flexible plates and shallow shells is studied. Namely, a wide class of the mentioned objects is analyzed including flexible plates and cylinder-like panels of infinite length, rectangular spherical and cylindrical shells, closed cylindrical shells, axially symmetric plates, as well as spherical and conical shells. The considered problems are solved by the Bubnov–Galerkin and higher approximation Ritz methods. Convergence and validation of those methods are studied. The Cauchy problems are solved mainly by the fourth Runge-Kutta method, although all variants of the Runge-Kutta methods are considered. New scenarios of transition from regular to chaotic orbits are detected, analyzed and discussed. First part of the paper is devoted to the validation of results obtained. This is why the same infinite length problem is reduced to that of a finite dimension through the FDM (Finite Difference Method) with the approximation order of O(c 2 ), BGM (Bubnov–Galerkin Method) or RM (Ritz Method) with higher approximations. We pay attention not only to convergence of the mentioned methods regarding the number of partitions of the interval [0, 1] in the FDM or regarding the number of terms in the series applied either in the BGM or RM methods, but we also compare the results obtained via the mentioned different approaches. Furthermore, a so called practical convergence of different Runge-Kutta type methods are tested starting from the second and ending with the eighth order. Second part of the work is devoted to a study of routes to chaos in the so far mentioned mechanical objects. For this purpose the so-called “dynamical charts” are constructed versus control parameters {q 0 , ω p }, where q 0 denotes the loading amplitude, and ω p is the loading frequency. The charts are constructed through analyses of frequency power spectra and the largest Lyapunov exponent (LE). Analysis of the mentioned charts

  2. Nostalgia fosters self-continuity: Uncovering the mechanism (social connectedness) and consequence (eudaimonic well-being).

    Science.gov (United States)

    Sedikides, Constantine; Wildschut, Tim; Cheung, Wing-Yee; Routledge, Clay; Hepper, Erica G; Arndt, Jamie; Vail, Kenneth; Zhou, Xinyue; Brackstone, Kenny; Vingerhoets, Ad J J M

    2016-06-01

    Nostalgia, a sentimental longing for one's past, is an emotion that arises from self-relevant and social memories. Nostalgia functions, in part, to foster self-continuity, that is, a sense of connection between one's past and one's present. This article examined, in 6 experiments, how nostalgia fosters self-continuity and the implications of that process for well-being. Nostalgia fosters self-continuity by augmenting social connectedness, that is, a sense of belongingness and acceptance (Experiments 1-4). Nostalgia-induced self-continuity, in turn, confers eudaimonic well-being, operationalized as subjective vitality (i.e., a feeling of aliveness and energy; Experiments 5-6). The findings clarify and expand the benefits of nostalgia for both the self-system and psychological adjustment. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  3. A Longitudinal Model of Continued IS Use: An Integrative View of Four Mechanisms Underlying Postadoption Phenomena

    OpenAIRE

    Sung S. Kim; Naresh K. Malhotra

    2005-01-01

    Although initial use is an important indicator of information system (IS) success, it does not necessarily lead to the desired managerial outcome unless the use continues. However, compared with the great amount of work done on IS adoption, little systematic effort has gone into providing insight into continued IS use over time. The objective of this study is to develop a longitudinal model of how users' evaluations and behavior evolve as they gain experience with the information technology a...

  4. Analysis of Äspö Pillar Stability Experiment: Continuous thermo-mechanical model development and calibration

    Czech Academy of Sciences Publication Activity Database

    Blaheta, Radim; Byczanski, Petr; Čermák, M.; Hrtus, Rostislav; Kohut, Roman; Kolcun, Alexej; Malík, Josef; Sysala, Stanislav

    2013-01-01

    Roč. 5, č. 2 (2013), s. 124-135 ISSN 1674-7755 Institutional support: RVO:68145535 Keywords : in situ pillar stability experiment * model calibration by back analysis * continuous mechanics * damage of granite rocks * Finite element method (FEM) Subject RIV: BA - General Mathematics http://www.sciencedirect.com/science/article/pii/S1674775513000103

  5. Comparing of mechanical behavior and microstructure of continuous cast and hot worked Cu Zn 40 Al 1 alloy

    International Nuclear Information System (INIS)

    Ebrahimzadeh, I.; Akbari, G. H.

    2007-01-01

    The performance of components produced by conventional route of a thermo mechanical process and those produced by continuous casting is interesting from different aspects of economy and technology. The performance of products in their service depends on their properties which are strongly influenced by production routes. In the present work the hardness, tensile and tensile-impact behaviors of Cu Zn 40 Al 1 alloys produced by continuous casting and extrusion were investigated. Micro structural features and fracture surfaces were studied by optical and scanning electron microscopy. Results showed that wrought samples exhibited higher absorbed energy than those of continuous cast samples. Reduction of impact velocity led to a higher absorbed energy in all samples. A systematic and meaningful relationship was observed between micro structural features and mechanical properties such as hardness, yield stress and ultimate tensile strength. Fractography investigations showed that fracture occurred with dimple formation in all cases

  6. New types of experimental data shape the use of enzyme kinetics for dynamic network modeling.

    Science.gov (United States)

    Tummler, Katja; Lubitz, Timo; Schelker, Max; Klipp, Edda

    2014-01-01

    Since the publication of Leonor Michaelis and Maude Menten's paper on the reaction kinetics of the enzyme invertase in 1913, molecular biology has evolved tremendously. New measurement techniques allow in vivo characterization of the whole genome, proteome or transcriptome of cells, whereas the classical enzyme essay only allows determination of the two Michaelis-Menten parameters V and K(m). Nevertheless, Michaelis-Menten kinetics are still commonly used, not only in the in vitro context of enzyme characterization but also as a rate law for enzymatic reactions in larger biochemical reaction networks. In this review, we give an overview of the historical development of kinetic rate laws originating from Michaelis-Menten kinetics over the past 100 years. Furthermore, we briefly summarize the experimental techniques used for the characterization of enzymes, and discuss web resources that systematically store kinetic parameters and related information. Finally, describe the novel opportunities that arise from using these data in dynamic mathematical modeling. In this framework, traditional in vitro approaches may be combined with modern genome-scale measurements to foster thorough understanding of the underlying complex mechanisms. © 2013 FEBS.

  7. Mechanism for multiplicity of steady states with distinct cell concentration in continuous culture of mammalian cells.

    Science.gov (United States)

    Yongky, Andrew; Lee, Jongchan; Le, Tung; Mulukutla, Bhanu Chandra; Daoutidis, Prodromos; Hu, Wei-Shou

    2015-07-01

    Continuous culture for the production of biopharmaceutical proteins offers the possibility of steady state operations and thus more consistent product quality and increased productivity. Under some conditions, multiplicity of steady states has been observed in continuous cultures of mammalian cells, wherein with the same dilution rate and feed nutrient composition, steady states with very different cell and product concentrations may be reached. At those different steady states, cells may exhibit a high glycolysis flux with high lactate production and low cell concentration, or a low glycolysis flux with low lactate and high cell concentration. These different steady states, with different cell concentration, also have different productivity. Developing a mechanistic understanding of the occurrence of steady state multiplicity and devising a strategy to steer the culture toward the desired steady state is critical. We establish a multi-scale kinetic model that integrates a mechanistic intracellular metabolic model and cell growth model in a continuous bioreactor. We show that steady state multiplicity exists in a range of dilution rate in continuous culture as a result of the bistable behavior in glycolysis. The insights from the model were used to devise strategies to guide the culture to the desired steady state in the multiple steady state region. The model provides a guideline principle in the design of continuous culture processes of mammalian cells. © 2015 Wiley Periodicals, Inc.

  8. Particular mechanism for continuously varying the compression ratio for an internal combustion engine

    Science.gov (United States)

    Raţiu, S.; Cătălinoiu, R.; Alexa, V.; Miklos, I.; Cioată, V.

    2018-01-01

    Variable compression ratio (VCR) is a technology to adjust the compression ratio of an internal combustion engine while the engine is in operation. The paper proposes the presentation of a particular mechanism allowing the position of the top dead centre to be changed, while the position of the bottom dead centre remains fixed. The kinematics of the mechanism is studied and its trajectories are graphically represented for different positions of operation.

  9. Nostalgia fosters self-continuity : Uncovering the mechanism (social connectedness) and consequence (eudaimonic well-being)

    NARCIS (Netherlands)

    Sedikides, Constantine; Wildschut, Tim; Cheung, Wing-Yee; Routledge, Clay; Hepper, Erica G; Arndt, Jamie; Vail, Kenneth; Zhou, Xinyue; Brackstone, Kenny; Vingerhoets, A.J.J.M.

    2016-01-01

    Nostalgia, a sentimental longing for one's past, is an emotion that arises from self-relevant and social memories. Nostalgia functions, in part, to foster self-continuity, that is, a sense of connection between one's past and one's present. This article examined, in 6 experiments, how nostalgia

  10. Record of Assessment Moderation Practice (RAMP): Survey Software as a Mechanism of Continuous Quality Improvement

    Science.gov (United States)

    Johnson, Genevieve Marie

    2015-01-01

    In higher education, assessment integrity is pivotal to student learning and satisfaction, and, therefore, a particularly important target of continuous quality improvement. This paper reports on the preliminary development and application of a process of recording and analysing current assessment moderation practices, with the aim of identifying…

  11. Isolating the Neural Mechanisms of Interference During Continuous Multisensory Dual-task Performance

    Science.gov (United States)

    2014-01-01

    of multitasking impairments have focused on the performance of two tasks presented in close temporal proximity on discrete trials; however, such...simultaneously and continuously monitor both auditory communications from pilots and visual radar displays. Drivers may choose to hold a cell phone

  12. Direct Measurement and Evaluation for Mechanical Engineering Programme Outcomes: Impact on Continuous Improvement

    Science.gov (United States)

    Tahir, Mohd Faizal Mat; Khamis, Nor Kamaliana; Wahid, Zaliha; Ihsan, Ahmad Kamal Ariffin Mohd; Ghani, Jaharah Ab; Sabri, Mohd Anas Mohd; Sajuri, Zainuddin; Abdullah, Shahrum; Sulong, Abu Bakar

    2013-01-01

    Universiti Kebangsaan Malaysia (UKM) is a research university that continuously undergoes an audit and accreditation process for the management of its courses. The Faculty of Engineering and the Built Environment (FKAB) is subjected to such processes, one of them is the auditing conducted by the Engineering Accreditation Council (EAC), which gives…

  13. Continuous depth-sensing nano-mechanical characterization of living, fixed and dehydrated cells attached on a glass substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yun-Ta; Liao, Jiunn-Der; Chang, Chia-Wei [Department of Materials Science and Engineering, National Cheng Kung University, No. 1, University Road, Tainan 70101, Taiwan (China); Lin, Chou-Ching K [Department of Neurology, National Cheng Kung University, No. 1, University Road, Tainan 70101, Taiwan (China); Ju, Ming-Shaung, E-mail: jdliao@mail.ncku.edu.tw [Department of Mechanical Engineering, National Cheng Kung University, No. 1, University Road, Tainan 70101, Taiwan (China)

    2010-07-16

    Continuous depth-sensing nano-indentation on living, fixed and dehydrated fibroblast cells was performed using a dynamic contact module and vertically measured from a pre-contact state to the glass substrate. The nano-indentation tip-on-cell approaches took advantage of finding a contact surface, followed by obtaining a continuous nano-mechanical profile along the nano-indentation depths. In the experiment, serial indentations from the leading edge, i.e., the lamellipodium to nucleus regions of living, fixed and dehydrated fibroblast cells were examined. Nano-indentations on a living cell anchored upon glass substrate were competent in finding the tip-on-cell contact surfaces and cell heights. For the result on the fixed and the dehydrated cells, cellular nano-mechanical properties were clearly characterized by continuous harmonic contact stiffness (HCS) measurements. The relations of HCS versus measured displacement, varied from the initial tip-on-cell contact to the glass substrate, were presumably divided into three stages, respectively induced by cellular intrinsic behavior, the substrate-dominant property, and the substrate property. This manifestation is beneficial to elucidate how the underlying substrate influences the interpretation of the nano-mechanical property of thin soft matter on a hard substrate. These findings, based upon continuous depth-sensing nano-indentations, are presumably valuable as a reference to related work, e.g., accomplished by atomic force microscopy.

  14. Continuous depth-sensing nano-mechanical characterization of living, fixed and dehydrated cells attached on a glass substrate

    International Nuclear Information System (INIS)

    Yang, Yun-Ta; Liao, Jiunn-Der; Chang, Chia-Wei; Lin, Chou-Ching K; Ju, Ming-Shaung

    2010-01-01

    Continuous depth-sensing nano-indentation on living, fixed and dehydrated fibroblast cells was performed using a dynamic contact module and vertically measured from a pre-contact state to the glass substrate. The nano-indentation tip-on-cell approaches took advantage of finding a contact surface, followed by obtaining a continuous nano-mechanical profile along the nano-indentation depths. In the experiment, serial indentations from the leading edge, i.e., the lamellipodium to nucleus regions of living, fixed and dehydrated fibroblast cells were examined. Nano-indentations on a living cell anchored upon glass substrate were competent in finding the tip-on-cell contact surfaces and cell heights. For the result on the fixed and the dehydrated cells, cellular nano-mechanical properties were clearly characterized by continuous harmonic contact stiffness (HCS) measurements. The relations of HCS versus measured displacement, varied from the initial tip-on-cell contact to the glass substrate, were presumably divided into three stages, respectively induced by cellular intrinsic behavior, the substrate-dominant property, and the substrate property. This manifestation is beneficial to elucidate how the underlying substrate influences the interpretation of the nano-mechanical property of thin soft matter on a hard substrate. These findings, based upon continuous depth-sensing nano-indentations, are presumably valuable as a reference to related work, e.g., accomplished by atomic force microscopy.

  15. Fabrication of Continuous Microfibers Containing Magnetic Nanoparticles by a Facile Magneto-Mechanical Drawing

    Science.gov (United States)

    Li, Jin-Tao; Jia, Xian-Sheng; Yu, Gui-Feng; Yan, Xu; He, Xiao-Xiao; Yu, Miao; Gong, Mao-Gang; Ning, Xin; Long, Yun-Ze

    2016-09-01

    A facile method termed magneto-mechanical drawing is used to produce polymer composite microfibers. Compared with electrospinning and other fiber spinning methods, magneto-mechanical drawing uses magnetic force generated by a permanent magnet to draw droplets of polymer/magnetic nanoparticle suspensions, leading to fabrication of composite microfibers. In addition, because of the rotating collector, it is easy to control the fiber assembly such as fibrous array in parallel or crossed fibrous structure. The general applicability of this method has also been proved by spinning different polymers and magnetic nanoparticles. The resultant fibers exhibit good superparamagnetic behavior at room temperature and ultrahigh stretchability (~443.8 %). The results indicate that magneto-mechanical drawing is a promising technique to fabricate magnetic and stretchable microfibers and devices.

  16. Physics of continuous media problems and solutions in electromagnetism, fluid mechanics and MHD

    CERN Document Server

    Vekstein, Grigory

    2013-01-01

    This book presents an excellent and exemplary collection of up-to-date exercises and their solutions on continuous media, covering a wide range of topics from electro-, magnetohydro- and fluid dynamics, and from the theory of elasticity. The author is an international expert with many years of research and teaching experience in the field. Each chapter begins with a comprehensive summary of definitions and the mathematical description of the physical laws necessary to understand and solve the series of problems that follow. The problems and exercises are a gradual built up in each of the topics and they introduce the reader step by step into the principles of the subject. The solutions are well explained and detailed with additional readings when necessary. This exercise book is written in a true scholarly manner that allows the reader to understand the basic principles and physical laws of continuous media. This problem-solving book is highly recommended to graduate and postgraduate students, postdoctoral re...

  17. Three dimensions thermal-mechanical model of the billet in continuous casting petal-like mould

    International Nuclear Information System (INIS)

    Li Jing; Wu Li; Cao Zhiqiang; Tingju, L; Wang Tongmin

    2012-01-01

    Petal-like mould is a novel mould which has been applied to the steel industry in recent years. The behavior of the petal-like billet in continuous casting mould plays an important role in designing mould. It is hard to be in situ measured during continuous casting, however, can be worked out by the way of numerical simulation. But the research about the model of the billet in petal-like mould is very little. A 3D finite-element model has been built to simulate the thermal and stress fields of the molten steel in petal-like mould in this paper. The dynamic thermal boundary condition and the effect of ferrostatic pressure have been considered in the model. The temperature and stress in the billet have been predicted by this model.

  18. Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene

    OpenAIRE

    Naveh, Naum; Shepelev, Olga; Kenig, Samuel

    2017-01-01

    Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, ...

  19. Processing-structure-mechanical property relationship in Ti-Nb microalloyed steel: Continuous cooling versus interrupted cooling

    Energy Technology Data Exchange (ETDEWEB)

    Natarajan, V.V. [Laboratory for Excellence in Advanced Steel Research, Materials Science and Engineering Program, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Liu, S. [Laboratory for Excellence in Advanced Steel Research, Materials Science and Engineering Program, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Challa, V.S.A. [Laboratory for Excellence in Advanced Steel Research, Materials Science and Engineering Program, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Misra, R.D.K., E-mail: dmisra2@utep.edu [Laboratory for Excellence in Advanced Steel Research, Materials Science and Engineering Program, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States); Sidorenko, D.M.; Mulholland, M.D.; Manohar, M.; Hartmann, J.E. [ArcelorMittal Global R& D Center, 3001 East Columbus Drive, East Chicago, IN 46312 (United States)

    2016-08-01

    The process parameters associated with thermo-mechanical controlled processing (TMCP) of steels play an important role in influencing the ultimate mechanical properties. The study of TMCP parameters have not received the required attention. In this regard, we elucidate here the impact of finish cooling temperature on interrupted cooling and compare with continuous cooling on microstructural evolution and precipitation behavior and associated mechanical properties in Ti-Nb microalloyed steels. The microstructural evolution was studied via transmission electron microscopy and electron back scattered diffraction (EBSD). The microstructure of continuously cooled and interrupted cooled steels with different finish exit temperatures consisted of polygonal ferrite, bainite and martensite/austenite constituent. However, the fraction of different microstructural constituents was different in each of the experimental steels. Similarly, there were differences in the distribution and average size of (Nb, Ti)C precipitates. The aforementioned differences in the microstructure and precipitation introduced differences in tensile properties. Furthermore, electron back scattered diffraction studies indicated distinct variation in average grain area and high angle boundaries between continuously cooled and interrupted cooled steels.

  20. Mechanical complications of continuous ambulatory peritoneal dialysis: Experience at the Ibn Sina University Hospital.

    Science.gov (United States)

    Flayou, Kaoutar; Ouzeddoun, Naima; Bayahia, Rabia; Rhou, Hakima; Benamar, Loubna

    2016-01-01

    Peritoneal dialysis is a new renal replacement therapy recently introduced in Morocco since 2006. Continuous ambulatory peritoneal dialysis has proven to be as effective as hemodialysis. However, it is associated with several complications. The aim of this study was to evaluate the outcome of complications in patients treated with peritoneal dialysis at our center. The nature of non-infectious complications was noted during follow-up in these patients. Fiftyseven complications were noted among 34 patients between June 2006 and June 2014. Catheter migration was the most common complication (36.8%), followed by obstruction (14%), dialysate leaks (14%), hemorrhagic complications (10.5%) and, finally, hernia (12.2%), catheter perforation (5.2%) and externalization (3.5%).

  1. Mechanical impacts of poloidal eddy currents on the continuous vacuum vessel of a tokamak

    International Nuclear Information System (INIS)

    In, Sang Ryul; Yoon, Byung Joo.

    1996-11-01

    Poloidal eddy currents are induced on the continuous torus vacuum vessel by changes of the toroidal field during the machine start-up (toroidal field coil charge), shut-down (toroidal field coil discharge) and plasma disruption (plasma diamagnetism change). Analytic forms for the eddy currents flowing on the vessel, consequent pressures and forces acting on it are presented in this report. The results are applied to typical operation modes of the KT-2 tokamak. Stress analysis for two typical operation modes of toroidal field damping during a machine shut-gown and plasma energy quench during a plasma disruption were carried out using 3D FEM code (ANSYS 5.2). (author). 5 tabs., 22 figs., 9 refs

  2. Compatibility conditions of a singular hypersurface in the relativistic mechanics of the continuous media

    International Nuclear Information System (INIS)

    Maugin, G.A.

    1976-01-01

    In this work the compatibility conditions verified by the discontinuities of relativistic fields and of their space-time and time-like derivatives up to be second order are systematically constructed in terms of the local geometry of the wave front (singular hypersurface). A new time-like derivative that generalizes Thomas' delta-derivative of classical continuum mechanics is thus introduced in the relativistic frame. It allows to formulate these conditions in compact forms. It is thus expected that the relativistic analogue of T.Y. Thomas' (1957) classical theory is produced [fr

  3. The mechanical properties, deformation and thermomechanical properties of alkali treated and untreated Agave continuous fibre reinforced epoxy composites

    International Nuclear Information System (INIS)

    Mylsamy, K.; Rajendran, I.

    2011-01-01

    Research highlights: → New renewable and biodegradable Agave americana fibre. → Environmentally free materials. → Good mechanical properties of Agave fibre reinforced epoxy composite materials. → Surface modification of the fibre (Alkali treatment) imported good mechanical properties. → Future scope in light weight materials manufacture. -- Abstract: The mechanical properties such as tensile, compressive, flexural, impact strength and water absorption of the alkali treated continuous Agave fibre reinforced epoxy composite (TCEC) and untreated continuous Agave fibre reinforced epoxy composite (UTCEC) were analysed. A comparison of the surfaces of TCEC and UTCEC composites was carried out by dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The thermomechanical properties of the composite reinforced with sodium hydroxide (NaOH) treated Agave fibres were considerably good as the shrinkage of the fibre during alkali treatment had facilitated more points of fibre resin interface. The SEM micrograph and FTIR spectra of the impact fracture surfaces of TCEC clearly demonstrate the better interfacial adhesion between fibre and the matrix. In both analyses the TCEC gave good performance than UTCEC and, thus, there is a scope for its application in light weight manufacture in future.

  4. Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene.

    Science.gov (United States)

    Naveh, Naum; Shepelev, Olga; Kenig, Samuel

    2017-01-01

    Impregnation of expandable graphite (EG) after thermal treatment with an epoxy resin containing surface-active agents (SAAs) enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called "stacked" graphene (SG). This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.

  5. Enhancement of mechanical and electrical properties of continuous-fiber-reinforced epoxy composites with stacked graphene

    Directory of Open Access Journals (Sweden)

    Naum Naveh

    2017-09-01

    Full Text Available Impregnation of expandable graphite (EG after thermal treatment with an epoxy resin containing surface-active agents (SAAs enhanced the intercalation of epoxy monomer between EG layers and led to further exfoliation of the graphite, resulting in stacks of few graphene layers, so-called “stacked” graphene (SG. This process enabled electrical conductivity of cured epoxy/SG composites at lower percolation thresholds, and improved thermo-mechanical properties were measured with either Kevlar, carbon or glass-fiber-reinforced composites. Several compositions with SAA-modified SG led to higher dynamic moduli especially at high temperatures, reflecting the better wetting ability of the modified nanoparticles. The hydrophilic/hydrophobic nature of the SAA dictates the surface energy balance. More hydrophilic SAAs promoted localization of the SG at the Kevlar/epoxy interface, and morphology seems to be driven by thermodynamics, rather than the kinetic effect of viscosity. This effect was less obvious with carbon or glass fibers, due to the lower surface energy of the carbon fibers or some incompatibility with the glass-fiber sizing. Proper choice of the surfactant and fine-tuning of the crosslink density at the interphase may provide further enhancements in thermo-mechanical behavior.

  6. The Molecular Mechanism of Action of Artemisinin—The Debate Continues

    Directory of Open Access Journals (Sweden)

    Stephen A. Ward

    2010-03-01

    Full Text Available Despite international efforts to ‘roll back malaria’ the 2008 World Malaria Report revealed the disease still affects approximately 3 billion people in 109 countries; 45 within the WHO African region. The latest report however does provide some ‘cautious optimism’; more than one third of malarious countries have documented greater than 50% reductions in malaria cases in 2008 compared to 2000. The goal of the Member States at the World Health Assembly and ‘Roll Back Malaria’ (RBM partnership is to reduce the numbers of malaria cases and deaths recorded in 2000 by 50% or more by the end of 2010. Although malaria is preventable it is most prevalent in poorer countries where prevention is difficult and prophylaxis is generally not an option. The burden of disease has increased by the emergence of multi drug resistant (MDR parasites which threatens the use of established and cost effective antimalarial agents. After a major change in treatment policies, artemisinins are now the frontline treatment to aid rapid clearance of parasitaemia and quick resolution of symptoms. Since artemisinin and its derivatives are eliminated rapidly, artemisinin combination therapies (ACT’s are now recommended to delay resistance mechanisms. In spite of these precautionary measures reduced susceptibility of parasites to the artemisinin-based component of ACT’s has developed at the Thai-Cambodian border, a historical ‘hot spot’ for MDR parasite evolution and emergence. This development raises serious concerns for the future of the artemsinins and this is not helped by controversy related to the mode of action. Although a number of potential targets have been proposed the actual mechanism of action remains ambiguous. Interestingly, artemisinins have also shown potent and broad anticancer properties in cell lines and animal models and are becoming established as anti-schistosomal agents. In this review we will discuss the recent evidence explaining

  7. Using Perceptual and Neuromuscular Responses to Estimate Mechanical Changes During Continuous Sets in the Bench Press.

    Science.gov (United States)

    Chapman, Mark; Larumbe-Zabala, Eneko; Gosss-Sampson, Mark; Triplett, N Travis; Naclerio, Fernando

    2018-02-22

    The present study analyzed the effectiveness of the OMNI-RES (0-10) and the electromyographic signal for monitoring changes in the movement velocity during a set to muscular failure performed with different relative loads in the bench press exercise (BP). Ten males (30.8 ± 5.7 years) were evaluated on eight separate days with 48 hours of rest between sessions. After determining the 1RM value, participants performed seven sets to failure with the following relative loads ranges: 3090%. The mean accelerative velocity (MAV), the Rating of Perceived Exertion (RPE) and the normalized root mean square (N-RMS) signal from the anterior deltoids were measured for every repetition of each set. The RPE expressed after the first repetition and when the maximum value of MAV was achieved over the sets was lower (p 0.80) than the RPE associated with a 10% drop in MAV and at failure. Furthermore, the initial RPE was useful to distinguish different loading zones between the light relative loads (3090%). Similar, but less clear, differences were observed for the N-RMS. In conclusion, apart from differentiating between relative loads, the RPE and in some cases N-RMS can both reflect changes associated with the initial, maximal, 10% drop in movement velocity and muscular failure during a continuous set in the BP.

  8. Mechanisms of comorbidity, continuity, and discontinuity in anxiety-related disorders.

    Science.gov (United States)

    McNaughton, Neil; Corr, Philip J

    2016-11-01

    We discuss comorbidity, continuity, and discontinuity of anxiety-related disorders from the perspective of a two-dimensional neuropsychology of fear (threat avoidance) and anxiety (threat approach). Pharmacological dissection of the "neurotic" disorders justifies both a categorical division between fear and anxiety and a subdivision of each mapped to a hierarchy of neural modules that process different immediacies of threat. It is critical that each module can generate normal responses, symptoms of another syndrome, or syndromal responses. We discuss the resultant possibilities for comorbid dysfunction of these modules both with each other and with some disorders not usually classified as anxiety related. The simplest case is symptomatic fear/anxiety comorbidity, where dysfunction in one module results in excess activity in a second, otherwise normal, module to generate symptoms and apparent comorbidity. More complex is syndromal fear/anxiety comorbidity, where more than one module is concurrently dysfunctional. Yet more complex are syndromal comorbidities of anxiety that go beyond the two dimensional fear/anxiety systems: depression, substance use disorder, and attention-deficit/hyperactivity disorder. Our account of attention-deficit/hyperactivity disorder-anxiety comorbidity entails discussion of the neuropsychology of externalizing disorders to account for the lack of anxiety comorbidity in some of these. Finally, we link the neuropsychology of disorder to personality variation, and to the development of a biomarker of variation in the anxiety system among individuals that, if extreme, may provide a means of unambiguously identifying the first of a range of anxiety syndromes.

  9. Study of the Mechanism of Liquid Slag Infiltration for Lubrication in Slab Continuous Casting

    Science.gov (United States)

    Zhang, Shaoda; Wang, Qiangqiang; He, Shengping; Wang, Qian

    2018-04-01

    Consistent and uniform lubrication of the solidifying shell, especially in the meniscus, is crucial for the smooth continuous casting operation and production of strands free of surface defects. Thus, the current study established a coupled model to study the inflow behavior of liquid slag to the mold-strand channel, taking the solidification of steel and slag and the periodic oscillation of mold into account. The difficulties and solutions for the simulation were described in detail. The predicted profiles of the slag rim and initial shell were in good agreement with the reports. The main results indicated that liquid slag could be squeezed out and back into the slag pool in a negative strip period while a large amount of liquid slag could infiltrate into the mold-strand channel. Thus, the amount of slag consumed in the negative strip period was relatively small compared with that in the positive strip period. The predicted variation of slag consumption during mold oscillation was periodic, and the average value was 0.274 kg/m2, which agreed well with the slag consumption in industrial practice. The current model can predict and optimize the oscillation parameters aiming at stable lubrication conditions.

  10. Microstructures and mechanical properties evolution of an Al–Fe–Cu alloy processed by repetitive continuous extrusion forming

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Xiangxin [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Zhang, Hui, E-mail: zhanghui63hunu@163.com [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Hunan Province Key Laboratory for Spray Deposition Technology and Application, Hunan University, Changsha 410082 (China); Ji, Xiankun [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

    2014-08-26

    Repetitive continuous extrusion forming process (R-Conform process), as a continuous severe plastic deformation method, was performed on a horizontal continuous casting Al–0.74Fe–0.23Cu alloy. The microstructural evolution and mechanical properties were studied by optical microscope, X-ray diffraction, scanning electron microscope, transmission electron microscope, and tensile testing. The results show that tensile ductility of the Al–0.74Fe–0.23Cu alloy is greatly improved but tensile strength is gradually decreased after repetitive Conform processing. The necking is more intense and the size of dimples becomes bigger with increasing Conform passes. The first pass Conform process induces obviously grains refining, dissolution of AlFe, AlFeSi and AlSi primary phases, strain-induced precipitation and transformation of crystal orientation distributions, but further Conform deformation only changes the redistribution of precipitates. The changes of mechanical properties may be attributed to a complex progress of recovery, recrystallization and redistribution of precipitates during repetitive Conform process.

  11. Continuity and completeness in physical theory: Schroedinger's return to the wave interpretation of quantum mechanics in the 1950's

    International Nuclear Information System (INIS)

    D'Agostino, S.

    1992-01-01

    In the 50s, Schroedinger proposed a new conception of a continuous theory of Quantum Mechanics, which remarkably modified his 1926 ideas on ondulatory mechanics. The lack of individuality of the atomic particles presented in the new statistics, and in Heisenberg's Indeterminacy Relations, was by him considered as an aspect of a more general crisis in the anthology itself of classical atomism. Unlike his 1926 ideas, he proposed now to represent the wave equation in an n-dimensional space and he considered second-quantization technique as the proper mathematical tool for his new physical conception. Although he accepted that space-time discontinuities and casual gaps may appear here and there on the observational level (e.g. in the Indeterminacy Relations), he was convinced that they could be made compatible with a continuous pure theory, provided one accepted a suitable conception of the theory's epistemiological status. For him, only a continuous theory satisfied the conditions for a complete theory. On these matters, he thought he was somehow orthodox to the ideas of Hertz and Boltzmann, which were also reflected in the teaching of Exner. (author). 69 refs

  12. Continuous Modeling Technique of Fiber Pullout from a Cement Matrix with Different Interface Mechanical Properties Using Finite Element Program

    Directory of Open Access Journals (Sweden)

    Leandro Ferreira Friedrich

    Full Text Available Abstract Fiber-matrix interface performance has a great influence on the mechanical properties of fiber reinforced composite. This influence is mainly presented during fiber pullout from the matrix. As fiber pullout process consists of fiber debonding stage and pullout stage which involve complex contact problem, numerical modeling is a best way to investigate the interface influence. Although many numerical research works have been conducted, practical and effective technique suitable for continuous modeling of fiber pullout process is still scarce. The reason is in that numerical divergence frequently happens, leading to the modeling interruption. By interacting the popular finite element program ANSYS with the MATLAB, we proposed continuous modeling technique and realized modeling of fiber pullout from cement matrix with desired interface mechanical performance. For debonding process, we used interface elements with cohesive surface traction and exponential failure behavior. For pullout process, we switched interface elements to spring elements with variable stiffness, which is related to the interface shear stress as a function of the interface slip displacement. For both processes, the results obtained are very good in comparison with other numerical or analytical models and experimental tests. We suggest using the present technique to model toughening achieved by randomly distributed fibers.

  13. Microcontroller Based Proportional Derivative Plus Conditional Integral Controller for Electro-Mechanical Dual Acting Pulley Continuously Variable Transmission Ratio Control

    International Nuclear Information System (INIS)

    Budianto, A; Tawi, K B; Hussein, M; Supriyo, B; Kob, M S Che; Zulkifli, Mohd Ezlamy; Khairuldean A K; Daraoh, Aishah; Ariyono, S

    2012-01-01

    Electro-Mechanical Dual Acting Pulley (EMDAP) Continuously Variable Transmission (CVT) is a transmission utilized by electro-mechanical actuated system. It has a potential to reduce energy consumption because it only needs power during changing CVT ratio and no power is needed to maintain CVT ratio due to self lock mechanism design. This paper proposed simple proportional derivative plus conditional integral (PDCI) controller to control EMDAP CVT ratio which can be simply implemented on a microcontroller. This proposed controller used Astrom-Hagglund method and Ziegler-Nichols formula to tune PDCI gain. The Proportional Derivative controller is directly activated from the start but Integral controller is only activated when the error value reaches error value setting point. Simulation using Matlab/Simulink software was conducted to evaluate PDCI system performance. The simulation results showed PDCI controller has ability to perform maximum overshoot 0.1%, 0.001 steady state error and 0.5s settling time. For clamping condition, settling time is about 11.46s during changing ratio from 2.0 to 0.7, while for release condition, settling time is about 8.33s during changing ratio from 0.7 to 2.0.

  14. Vibration parameters assessment to develop a continuous lateral canopy shaker for mechanical harvesting of traditional olive trees

    Energy Technology Data Exchange (ETDEWEB)

    Sola-Guirado, R.R.; Jimenez-Jimenez, F.; Blanco-Roldan, G.L.; Castro-Garcia, S.; Castillo-Ruiz, F.J.; Gil Ribes, J.A.

    2016-11-01

    The fruit harvesting is a key factor involving both product quality and profitability. Particularly, mechanical harvesting of traditional oil olive orchards is hint by tree training system for manual harvesting, tree size and several and slanted trunks which makes difficult trunk shaker work. Therefore, canopy shaker technology could be a feasible alternative to develop an integral harvester able to work on irregular canopies. The aim of this research was to determine vibration parameters applied to the olive tree for efficient mechanical harvesting by canopy shaker measuring fruit removal efficiency and debris. In this work, a continuous lateral canopy shaker harvester has been developed and tested on large olive trees in order to analyse the operating harvester parameters and tree properties to improve mutual adaptation. Vibration amplitude and frequency, rod density and ground speed were assessed. Vibration amplitude and frequency beside ground speed were decisive factors on fruit removal efficiency. Increasing rod density has not influenced on removal efficiency although it increased significantly debris. Promising results has been reached with 77.3% of removal efficiency, applying a 28 s shaking duration, 0.17 m amplitude vibration and 12 rod drum. This result was obtained reporting 0.26 s of accumulative shaking time over 200 m/s2 resultant acceleration. The canopy shaker mechanism enabled more than 65% of detached fruits to fall vertically, facilitating catch fruit. In order to improve removal efficiency it is advisable to adapt trees, set high amplitude in the shaker mechanism, and enhance the contact time between rods and tree. (Author)

  15. Optimization of voltage output of energy harvesters with continuous mechanical rotation extracted from human motion (Conference Presentation)

    Science.gov (United States)

    Rashid, Evan; Hamidi, Armita; Tadesse, Yonas

    2017-04-01

    With increasing popularity of portable devices for outdoor activities, portable energy harvesting devices are coming into spot light. The next generation energy harvester which is called hybrid energy harvester can employ more than one mechanism in a single device to optimize portion of the energy that can be harvested from any source of waste energy namely motion, vibration, heat and etc. In spite of few recent attempts for creating hybrid portable devices, the level of output energy still needs to be improved with the intention of employing them in commercial electronic systems or further applications. Moreover, implementing a practical hybrid energy harvester in different application for further investigation is still challenging. This proposal is projected to incorporate a novel approach to maximize and optimize the voltage output of hybrid energy harvesters to achieve a greater conversion efficiency normalized by the total mass of the hybrid device than the simple arithmetic sum of the individual harvesting mechanisms. The energy harvester model previously proposed by Larkin and Tadesse [1] is used as a baseline and a continuous unidirectional rotation is incorporated to maximize and optimize the output. The device harvest mechanical energy from oscillatory motion and convert it to electrical energy through electromagnetic and piezoelectric systems. The new designed mechanism upgrades the device in a way that can harvest energy from both rotational and linear motions by using magnets. Likewise, the piezoelectric section optimized to harvest at least 10% more energy. To the end, the device scaled down for tested with different sources of vibrations in the immediate environment, including machinery operation, bicycle, door motion while opening and closing and finally, human motions. Comparing the results from literature proved that current device has capability to be employed in commercial small electronic devices for enhancement of battery usage or as a backup

  16. Postictal apnea as an important mechanism for SUDEP: A near-SUDEP with continuous EEG-ECG-EMG recording.

    Science.gov (United States)

    Jin, Lang; Zhang, Ying; Wang, Xiao-Li; Zhang, Wen-Juan; Liu, Yong-Hong; Jiang, Zhao

    2017-09-01

    Sudden unexpected death in epilepsy (SUDEP) is one of the most frequent causes of death among patients with epilepsy. Most SUDEP or near-SUDEP are unwitnessed and not observed or recorded during video-EEG recording in epilepsy monitoring units. This report describes a young woman with post ictal apnea and generalized EEG suppression (PGES) after a secondary generalized tonic-clonic seizure (sGTCS). This was accompanied by bradycardia and then ventricular tachycardia (VT). But at the end of VT, the patient's breath recovered without any intervention, such as cardio-respiratory resuscitation. This case report with continuous EEG, EKG, EMG during near SUDEP may provide insights into the mechanism of action. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. A new two-photon mechanism of the formation of a continuous spectrum of photons emitted by secondary emission products of atomic particles

    International Nuclear Information System (INIS)

    Veksler, V.I.

    1986-01-01

    A two-photon mechanism of the formation of a continuous spectrum of photons emitted by products of metal sputtering is considered. The following process of the two-photon mechanism is considered: the continuous spectrum is formed under quadrupole two-photon transitions in sputtered excited atoms having vacancies at the d level in atoms of transition metals or at the of level in lanthanides found against the filled conduction band. It is shown that the suggested mechanism should play an essential role in the formation of the continuous spectrum of optical radiation

  18. Investigation on the Mechanical and Electrical Behavior of a Tuning Fork-Shaped Ionic Polymer Metal Composite Actuator with a Continuous Water Supply Mechanism.

    Science.gov (United States)

    Feng, Guo-Hua; Huang, Wei-Lun

    2016-03-25

    This paper presents an innovative tuning fork-shaped ionic polymer metal composite (IPMC) actuator. With an integrated soft strain gauge and water supply mechanism (WSM), the surface strain of the actuator can be sensed in situ, and providing a continuous water supply maintains the water content inside the IPMC for long-term operation in air. The actuator was fabricated using a micromachining technique and plated with a nickel electrode. The device performance was experimentally characterized and compared with an actuator without a WSM. A large displacement of 1.5 mm was achieved for a 6 mm-long prong with 7-V dc actuation applied for 30 s. The measured current was analyzed using an electrochemical model. The results revealed that the faradaic current plays a crucial role during operation, particularly after 10 s. The measured strain confirms both the bending and axial strain generation during the open-and-close motion of the actuator prongs. Most of the water loss during device operation was due to evaporation rather than hydrolysis. The constructed WSM effectively maintained the water content inside the IPMC for long-term continuous operation.

  19. Applications of continuity and discontinuity of a fractional derivative of the wave functions to fractional quantum mechanics

    International Nuclear Information System (INIS)

    Dong Jianping; Xu Mingyu

    2008-01-01

    The space fractional Schroedinger equation with a finite square potential, periodic potential, and delta-function potential is studied in this paper. We find that the continuity or discontinuity condition of a fractional derivative of the wave functions should be considered to solve the fractional Schroedinger equation in fractional quantum mechanics. More parity states than those given by standard quantum mechanics for the finite square potential well are obtained. The corresponding energy equations are derived and then solved by graphical methods. We show the validity of Bloch's theorem and reveal the energy band structure for the periodic potential. The jump (discontinuity) condition for the fractional derivative of the wave function of the delta-function potential is given. With the help of the jump condition, we study some delta-function potential fields. For the delta-function potential well, an alternate expression of the wave function (the H function form of it was given by Dong and Xu [J. Math. Phys. 48, 072105 (2007)]) is obtained. The problems of a particle penetrating through a delta-function potential barrier and the fractional probability current density of the particle are also discussed. We study the Dirac comb and show the energy band structure at the end of the paper

  20. Evolution of Cooperation in Continuous Prisoner's Dilemma Games on Barabasi—Albert Networks with Degree-Dependent Guilt Mechanism

    Science.gov (United States)

    Wang, Xian-Jia; Quan, Ji; Liu, Wei-Bing

    2012-05-01

    This paper studies the continuous prisoner's dilemma games (CPDG) on Barabasi—Albert (BA) networks. In the model, each agent on a vertex of the networks makes an investment and interacts with all of his neighboring agents. Making an investment is costly, but which benefits its neighboring agents, where benefit and cost depend on the level of investment made. The payoff of each agent is given by the sum of payoffs it receives in its interactions with all its neighbors. Not only payoff, individual's guilty emotion in the games has also been considered. The negative guilty emotion produced in comparing with its neighbors can reduce the utility of individuals directly. We assume that the reduction amount depends on the individual's degree and a baseline level parameter. The group's cooperative level is characterized by the average investment of the population. Each player makes his investment in the next step based on a convex combination of the investment of his best neighbors in the last step, his best history strategies in the latest steps which number is controlled by a memory length parameter, and a uniformly distributed random number. Simulation results show that this degree-dependent guilt mechanism can promote the evolution of cooperation dramatically comparing with degree-independent guilt or no guilt cases. Imitation, memory, uncertainty coefficients and network structure also play determinant roles in the cooperation level of the population. All our results may shed some new light on studying the evolution of cooperation based on network reciprocity mechanisms.

  1. Evolution of Cooperation in Continuous Prisoner's Dilemma Games on Barabasi-Albert Networks with Degree-Dependent Guilt Mechanism

    International Nuclear Information System (INIS)

    Wang Xianjia; Quan Ji; Liu Weibing

    2012-01-01

    This paper studies the continuous prisoner's dilemma games (CPDG) on Barabasi-Albert (BA) networks. In the model, each agent on a vertex of the networks makes an investment and interacts with all of his neighboring agents. Making an investment is costly, but which benefits its neighboring agents, where benefit and cost depend on the level of investment made. The payoff of each agent is given by the sum of payoffs it receives in its interactions with all its neighbors. Not only payoff, individual's guilty emotion in the games has also been considered. The negative guilty emotion produced in comparing with its neighbors can reduce the utility of individuals directly. We assume that the reduction amount depends on the individual's degree and a baseline level parameter. The group's cooperative level is characterized by the average investment of the population. Each player makes his investment in the next step based on a convex combination of the investment of his best neighbors in the last step, his best history strategies in the latest steps which number is controlled by a memory length parameter, and a uniformly distributed random number. Simulation results show that this degree-dependent guilt mechanism can promote the evolution of cooperation dramatically comparing with degree-independent guilt or no guilt cases. Imitation, memory, uncertainty coefficients and network structure also play determinant roles in the cooperation level of the population. All our results may shed some new light on studying the evolution of cooperation based on network reciprocity mechanisms. (interdisciplinary physics and related areas of science and technology)

  2. Efficacy of continuous versus intermittent subglottic secretion drainage in preventing ventilator-associated pneumonia in patients requiring mechanical ventilation: A single-center randomized controlled trial.

    Science.gov (United States)

    Fujimoto, Hiroko; Yamaguchi, Osamu; Hayami, Hajime; Shimosaka, Mika; Tsuboi, Sayaka; Sato, Mitsunori; Takebayashi, Shigeo; Morita, Satoshi; Saito, Mari; Goto, Takahisa; Kurahashi, Kiyoyasu

    2018-03-23

    Aspiration of subglottic secretion is a widely used intervention to prevent ventilator-associated pneumonia (VAP). This study aimed to compare the efficacy of continuous and intermittent subglottic secretion drainage (SSD) in preventing VAP. A single-center randomized controlled trial was conducted on adult postoperative patients who were expected to undergo mechanical ventilation for more than 48 hours. Primary outcome measure was incidence of VAP and secondary outcome measures were length of mechanical ventilation and intensive-care unit (ICU) stay. Fifty-nine patients received continuous SSD, while 60 patients received intermittent SSD. Of these 119 patients, 88 (74%) were excluded and 15 and 16 patients were allocated to receive continuous and intermittent SSD, respectively. VAP was detected in 4 (26.7%) and 7 (43.8%) patients in the continuous and intermittent groups, respectively, (p=0.320). The length of mechanical ventilation was significantly shorter (p=0.034) in the continuous group (99.5±47.1 h) than in the intermittent group (159.9±94.5 h). The length of ICU stay was also shorter (p=0.0097) in the continuous group (6.3±2.1 days) than the intermittent group (9.8±4.8 days). Although continuous SSD did not reduce the incidence of VAP, it reduced the length of mechanical ventilation and ICU stay when compared to intermittent SSD.

  3. Continuous Positive Airway Pressure versus Mechanical Ventilation on the Fist Day of Life in Very Low-Birth-Weight Infants

    Science.gov (United States)

    Flannery, Dustin D.; O’Donnell, Elizabeth; Kornhauser, Mike; Dysart, Kevin; Greenspan, Jay; Aghai, Zubair H.

    2017-01-01

    Objective The objective of this study was to determine differences in the incidence of bronchopulmonary dysplasia (BPD) or death in very low-birth-weight (VLBW) infants managed successfully on continuous positive airway pressure (CPAP) versus mechanical ventilation on the first day of life (DOL). Study Design This is a retrospective analysis of the Alere neonatal database for infants born between January 2009 and December 2014, weighing ≤ 1,500 g. Baseline demographics, clinical characteristics, and outcomes were compared between the two groups. Multivariate regression analysis was performed to control the variables that differ in bivariate analysis. Results In this study, 4,629 infants (birth weight 1,034 ± 290 g, gestational age 28.1 ± 2.5 weeks) met the inclusion criteria. The successful use of early CPAP was associated with a significant reduction in BPD or death (p CPAP on the first DOL in VLBW infants is associated with a reduced risk of BPD or death. PMID:27057767

  4. Efficacy of combined local mechanical vibrations, continuous passive motion and thermotherapy in the management of osteoarthritis of the knee.

    Science.gov (United States)

    Kitay, G S; Koren, M J; Helfet, D L; Parides, M K; Markenson, J A

    2009-10-01

    We evaluated the efficacy of combined mechanical vibrations, continuous passive motion (CPM) and heat on the severity of pain in management of osteoarthritis of the knee (OA-K). In this controlled, double crossover study, 71 OA-K patients were randomized in Phase 1 to receive 4 weeks active treatment consisting of two 20-min sessions per day (34 patients, Group AB) or treatment with a sham device (37 patients, Group BA). This was followed by a 2-week washout period (Phase 2). In Phase 3, patients crossed over so that Group AB was treated with the sham device and Group BA received active treatment for an additional 4 weeks. Patient assessments of pain (visual analog scale, VAS) and Western Ontario and McMaster Universities (WOMAC) OA index were performed at baseline and at study weeks 2, 4, 6, and 10. Net treatment effects were estimated by comparing outcomes between active and sham treatment study phases. Treatment benefits were noted for both of the trial's two pre-specified primary endpoints, VAS and WOMAC. VAS was reduced at all follow-up time points for patients receiving active treatment compared to sham treatment with a net treatment effect of 14.4+/-4.1 mm (P=0.001). Similarly, the WOMAC score was reduced significantly with active treatment at all measured points with a net effect of 8.8+/-1.9 points (Ppain, improves ROM and the quality of life in patients with OA-K (ClinicalTrials.gov registration number: NCT00858416).

  5. General chemistry

    International Nuclear Information System (INIS)

    2009-01-01

    This book explains chemical equilibrium with nature and characteristic of chemical equilibrium, law of mass action and direction of chemical equilibrium, acid-base equilibrium with principle of acid and base and amino acid, solubility and precipitation equilibrium with equilibrium of solubility, complex ion and solubility, electrochemistry on oxidation-reduction reaction, battery and fuel cell, decay and electrolysis, chemical reaction speed and nuclear reaction with Michaelis-Menten mechanism safety of nuclear, transition elements and coordination compound with introduction, name, structure and ligand EDTA and solid structure with categorization of solid and unit cell.

  6. Why Is Past Depression the Best Predictor of Future Depression? Stress Generation as a Mechanism of Depression Continuity in Girls

    Science.gov (United States)

    Rudolph, Karen D.; Flynn, Megan; Abaied, Jamie L.; Groot, Alison; Thompson, Renee

    2009-01-01

    This study examined whether a transactional interpersonal life stress model helps to explain the continuity in depression over time in girls. Youth (86 girls, 81 boys; M age = 12.41, SD = 1.19) and their caregivers participated in a three-wave longitudinal study. Depression and episodic life stress were assessed with semistructured interviews.…

  7. The effect of microstructure and texture evolution on mechanical properties of low-carbon steel processed by the continuous hybrid process

    International Nuclear Information System (INIS)

    Hwang, Sun Kwang; Baek, Hyun Moo; Son, Il-Heon; Im, Yong-Taek; Bae, Chul Min

    2013-01-01

    In this paper, the continuous hybrid process is newly designed and applied for producing grain-refined long and large cross-section wires of low-carbon steel at high speed at room temperature. The initial specimen, with a diameter of 13 mm, continuously passes through the rolls, equal channel angular pressing (ECAP) dies, and wire-drawing dies in sequence during the process. The specimens deformed by the continuous hybrid process without and with the wire-drawing dies were obtained to investigate the role in the deformation separately. Their microstructures, textures, and mechanical properties were investigated by optical microscopy (OM), electron backscattering diffraction (EBSD), X-ray diffraction (XRD), tension, and Vickers micro-hardness tests and were compared with those for the case processed by the conventional wire-drawing process. According to the present investigation, the continuous hybrid process can more efficiently manufacture fine-grained wires with a strong shear texture in a continuous way than the conventional wire-drawing process can. In addition, the ultimate tensile strength value of the specimen processed by the continuous hybrid process was 23.9% higher, although the elongation was slightly lower than the one produced by the conventional wire-drawing process. The plastic deformation was mainly imposed by the ECAP dies, and the wire-drawing dies improve the dimensional accuracy and increase the local strain homogeneity in the continuous hybrid process. It is demonstrated that the continuous hybrid process might be beneficial in commercializing a continuous application of the severe plastic deformation process for producing grain-refined wires for industrial applications

  8. Why is Past Depression the Best Predictor of Future Depression? Stress Generation as a Mechanism of Depression Continuity in Girls

    OpenAIRE

    Rudolph, Karen D.; Flynn, Megan; Abaied, Jamie; Groot, Alison; Thompson, Renee

    2009-01-01

    This study examined whether a transactional interpersonal life stress model helps to explain the continuity in depression over time in girls. Youth (86 girls, 81 boys; M age = 12.41, SD = 1.19) and their caregivers participated in a three-wave longitudinal study. Depression and episodic life stress were assessed with semi-structured interviews. Path analysis provided support for a transactional interpersonal life stress model in girls but not in boys, wherein depression predicted the generati...

  9. Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. 1 and 2

    International Nuclear Information System (INIS)

    Brieger, M.

    2004-01-01

    The established statistical interpretation of quantum mechanics never envisioned our today's ability to handle and investigate single particles in trap devices. After scrutinizing the development of quantum mechanics, we point out that Schroedinger's equation establishes an energy representation, which obtains the energy eigenvalues as extrema of the energy curve or on the energy hypersurface, respectively. We also strongly emphasize its never exhausted capability of accounting in classical terms and full detail for the dynamics of single particles in closed systems. This is demonstrated for several familiar examples. They show that the eigensolutions to Schroedinger's equation must not blindly be identified with physically stationary states. The gained insight into the true dynamics allows to describe, without involving QED, the time evolution of a complete spontaneous transition as being driven by unbalanced internal dynamics. This mechanism relies on the fact that perfect balances are only possible in the exact extrema of the total energy and that any deviation, which is characterized by nonstationary states, makes multipole moments oscillate and emit electromagnetic radiation. (orig.)

  10. Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Brieger, M. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Technische Physik

    2004-07-01

    The established statistical interpretation of quantum mechanics never envisioned our today's ability to handle and investigate single particles in trap devices. After scrutinizing the development of quantum mechanics, we point out that Schroedinger's equation establishes an energy representation, which obtains the energy eigenvalues as extrema of the energy curve or on the energy hypersurface, respectively. We also strongly emphasize its never exhausted capability of accounting in classical terms and full detail for the dynamics of single particles in closed systems. This is demonstrated for several familiar examples. They show that the eigensolutions to Schroedinger's equation must not blindly be identified with physically stationary states. The gained insight into the true dynamics allows to describe, without involving QED, the time evolution of a complete spontaneous transition as being driven by unbalanced internal dynamics. This mechanism relies on the fact that perfect balances are only possible in the exact extrema of the total energy and that any deviation, which is characterized by nonstationary states, makes multipole moments oscillate and emit electromagnetic radiation. (orig.)

  11. Formation of large colonies: a defense mechanism of Microcystis aeruginosa under continuous grazing pressure by flagellate Ochromonas sp.

    Directory of Open Access Journals (Sweden)

    Fanxiang Kong

    2012-01-01

    Full Text Available Induced colony formation under grazing pressure has been reported in our previous results. However, the colonies induced in these studies comprised only tens of cells which are far smaller than the naturally occurring colonies. In this work, unicellular Microcystis aeruginosa Kützing were co-cultivated with flagellate Ochromonas sp. for 50 d to investigate colony formation in M. aeruginosa under continuous grazing pressure. Results revealed that colonial M. aeruginosa formed on the 10th d under the grazing pressure of flagellate. These algal colonies resulted from the daughter cells of freshly dividing cells that failed to separate during the reproductive process. The diameters and cell numbers of the colonies increased slowly with time. Under continuous grazing pressure by Ochromonas sp. for 50 d, the diameter of some colonies reached over 180 μm. Analysis showed that the extracellular polysaccharide (EPS content and relative gas vesicle (RGV of each cell increased significantly after colony formation. However, there was no significant difference on the monosaccharide composition between unicellular and colonial M. aeruginosa. The loose aggregation of cells in the floating colonies suggests that a correlation probably exists between cell compactness and colony buoyancy.

  12. A Method to Extract the Intrinsic Mechanical Properties of Soft Metallic Thin Films Based on Nanoindentation Continuous Stiffness Measurement Technique

    International Nuclear Information System (INIS)

    Zhou, X Y; Jiang, Z D; Wang, H R; Zhu, Q

    2006-01-01

    In order to determine accurately the intrinsic hardness of the soft metallic thin film on a hard substrate using nanoindentation, a proper methodology irrespective of several important effects the Oliver-Pharr method concerns is described. First, the original analysis data such as the load, P, and contact stiffness, S, as a function of the indentation depth, h, are acquired by means of the continuous stiffness measurement (CSM) technique. By CSM, the complicating effects including indentation creep behaviour of metal materials as well as thermal drift on the measured results are avoided effectively. Then, the hardness of film-only is calculated via a material characteristic parameter, P/S 2 , which is independent of the contact area, A, based on the constant modulus assumption method. In this way, the influences of the substrate contribution and material pile-up behaviour needn't be accounted for. Guided by above ideas, moreover, a 504 nm Au film on the glass substrate system was chosen to study. The results show that the hardness of Au thin film is 1.6±1 GPa, which agree well with the literature. While the composite hardness measured by Oliver-Pharr method is between 2∼3GPa, obviously, which is overestimated. This implies the present methodology is a more accurate and simple way for extracting the true hardness of the soft metallic thin films

  13. Continuity and completeness in physical theory: Schroedinger`s return to the wave interpretation of quantum mechanics in the 1950`s

    Energy Technology Data Exchange (ETDEWEB)

    D`Agostino, S. [Rome Univ. (Italy)

    1992-12-31

    In the 50s, Schroedinger proposed a new conception of a continuous theory of Quantum Mechanics, which remarkably modified his 1926 ideas on ondulatory mechanics. The lack of individuality of the atomic particles presented in the new statistics, and in Heisenberg`s Indeterminacy Relations, was by him considered as an aspect of a more general crisis in the anthology itself of classical atomism. Unlike his 1926 ideas, he proposed now to represent the wave equation in an n-dimensional space and he considered second-quantization technique as the proper mathematical tool for his new physical conception. Although he accepted that space-time discontinuities and casual gaps may appear here and there on the observational level (e.g. in the Indeterminacy Relations), he was convinced that they could be made compatible with a continuous pure theory, provided one accepted a suitable conception of the theory`s epistemiological status. For him, only a continuous theory satisfied the conditions for a complete theory. On these matters, he thought he was somehow orthodox to the ideas of Hertz and Boltzmann, which were also reflected in the teaching of Exner. (author). 69 refs.

  14. Investigation of continuous effect modifiers in a meta-analysis on higher versus lower PEEP in patients requiring mechanical ventilation--protocol of the ICEM study.

    Science.gov (United States)

    Kasenda, Benjamin; Sauerbrei, Willi; Royston, Patrick; Briel, Matthias

    2014-05-20

    Categorizing an inherently continuous predictor in prognostic analyses raises several critical methodological issues: dependence of the statistical significance on the number and position of the chosen cut-point(s), loss of statistical power, and faulty interpretation of the results if a non-linear association is incorrectly assumed to be linear. This also applies to a therapeutic context where investigators of randomized clinical trials (RCTs) are interested in interactions between treatment assignment and one or more continuous predictors. Our goal is to apply the multivariable fractional polynomial interaction (MFPI) approach to investigate interactions between continuous patient baseline variables and the allocated treatment in an individual patient data meta-analysis of three RCTs (N = 2,299) from the intensive care field. For each study, MFPI will provide a continuous treatment effect function. Functions from each of the three studies will be averaged by a novel meta-analysis approach for functions. We will plot treatment effect functions separately for each study and also the averaged function. The averaged function with a related confidence interval will provide a suitable basis to assess whether a continuous patient characteristic modifies the treatment comparison and may be relevant for clinical decision-making. The compared interventions will be a higher or lower positive end-expiratory pressure (PEEP) ventilation strategy in patients requiring mechanical ventilation. The continuous baseline variables body mass index, PaO2/FiO2, respiratory compliance, and oxygenation index will be the investigated potential effect modifiers. Clinical outcomes for this analysis will be in-hospital mortality, time to death, time to unassisted breathing, and pneumothorax. This project will be the first meta-analysis to combine continuous treatment effect functions derived by the MFPI procedure separately in each of several RCTs. Such an approach requires individual

  15. Emergence of dynamic cooperativity in the stochastic kinetics of fluctuating enzymes

    International Nuclear Information System (INIS)

    Kumar, Ashutosh; Chatterjee, Sambarta; Nandi, Mintu; Dua, Arti

    2016-01-01

    Dynamic co-operativity in monomeric enzymes is characterized in terms of a non-Michaelis-Menten kinetic behaviour. The latter is believed to be associated with mechanisms that include multiple reaction pathways due to enzymatic conformational fluctuations. Recent advances in single-molecule fluorescence spectroscopy have provided new fundamental insights on the possible mechanisms underlying reactions catalyzed by fluctuating enzymes. Here, we present a bottom-up approach to understand enzyme turnover kinetics at physiologically relevant mesoscopic concentrations informed by mechanisms extracted from single-molecule stochastic trajectories. The stochastic approach, presented here, shows the emergence of dynamic co-operativity in terms of a slowing down of the Michaelis-Menten (MM) kinetics resulting in negative co-operativity. For fewer enzymes, dynamic co-operativity emerges due to the combined effects of enzymatic conformational fluctuations and molecular discreteness. The increase in the number of enzymes, however, suppresses the effect of enzymatic conformational fluctuations such that dynamic co-operativity emerges solely due to the discrete changes in the number of reacting species. These results confirm that the turnover kinetics of fluctuating enzyme based on the parallel-pathway MM mechanism switches over to the single-pathway MM mechanism with the increase in the number of enzymes. For large enzyme numbers, convergence to the exact MM equation occurs in the limit of very high substrate concentration as the stochastic kinetics approaches the deterministic behaviour.

  16. Emergence of dynamic cooperativity in the stochastic kinetics of fluctuating enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ashutosh; Chatterjee, Sambarta; Nandi, Mintu; Dua, Arti, E-mail: arti@iitm.ac.in [Department of Chemistry, Indian Institute of Technology, Madras, Chennai 600036 (India)

    2016-08-28

    Dynamic co-operativity in monomeric enzymes is characterized in terms of a non-Michaelis-Menten kinetic behaviour. The latter is believed to be associated with mechanisms that include multiple reaction pathways due to enzymatic conformational fluctuations. Recent advances in single-molecule fluorescence spectroscopy have provided new fundamental insights on the possible mechanisms underlying reactions catalyzed by fluctuating enzymes. Here, we present a bottom-up approach to understand enzyme turnover kinetics at physiologically relevant mesoscopic concentrations informed by mechanisms extracted from single-molecule stochastic trajectories. The stochastic approach, presented here, shows the emergence of dynamic co-operativity in terms of a slowing down of the Michaelis-Menten (MM) kinetics resulting in negative co-operativity. For fewer enzymes, dynamic co-operativity emerges due to the combined effects of enzymatic conformational fluctuations and molecular discreteness. The increase in the number of enzymes, however, suppresses the effect of enzymatic conformational fluctuations such that dynamic co-operativity emerges solely due to the discrete changes in the number of reacting species. These results confirm that the turnover kinetics of fluctuating enzyme based on the parallel-pathway MM mechanism switches over to the single-pathway MM mechanism with the increase in the number of enzymes. For large enzyme numbers, convergence to the exact MM equation occurs in the limit of very high substrate concentration as the stochastic kinetics approaches the deterministic behaviour.

  17. Emergence of dynamic cooperativity in the stochastic kinetics of fluctuating enzymes

    Science.gov (United States)

    Kumar, Ashutosh; Chatterjee, Sambarta; Nandi, Mintu; Dua, Arti

    2016-08-01

    Dynamic co-operativity in monomeric enzymes is characterized in terms of a non-Michaelis-Menten kinetic behaviour. The latter is believed to be associated with mechanisms that include multiple reaction pathways due to enzymatic conformational fluctuations. Recent advances in single-molecule fluorescence spectroscopy have provided new fundamental insights on the possible mechanisms underlying reactions catalyzed by fluctuating enzymes. Here, we present a bottom-up approach to understand enzyme turnover kinetics at physiologically relevant mesoscopic concentrations informed by mechanisms extracted from single-molecule stochastic trajectories. The stochastic approach, presented here, shows the emergence of dynamic co-operativity in terms of a slowing down of the Michaelis-Menten (MM) kinetics resulting in negative co-operativity. For fewer enzymes, dynamic co-operativity emerges due to the combined effects of enzymatic conformational fluctuations and molecular discreteness. The increase in the number of enzymes, however, suppresses the effect of enzymatic conformational fluctuations such that dynamic co-operativity emerges solely due to the discrete changes in the number of reacting species. These results confirm that the turnover kinetics of fluctuating enzyme based on the parallel-pathway MM mechanism switches over to the single-pathway MM mechanism with the increase in the number of enzymes. For large enzyme numbers, convergence to the exact MM equation occurs in the limit of very high substrate concentration as the stochastic kinetics approaches the deterministic behaviour.

  18. Comparison of the monotonic and cyclic mechanical properties of ultrafine-grained low carbon steels processed by continuous and conventional equal channel angular pressing

    International Nuclear Information System (INIS)

    Niendorf, T.; Böhner, A.; Höppel, H.W.; Göken, M.; Valiev, R.Z.; Maier, H.J.

    2013-01-01

    Highlights: ► UFG low-carbon steel was successfully processed by continuous ECAP-Conform. ► Continuously processed UFG steel shows high performance. ► High monotonic strength and good ductility. ► Microstructural stability under cyclic loading in the LCF regime. ► Established concepts can be used for predicting the properties. - Abstract: In the current study the mechanical properties of ultra-fine grained low carbon steel processed by conventional equal channel angular pressing and a continuous equal channel angular pressing-Conform process were investigated. Both monotonic and cyclic properties were determined for the steel in either condition and found to be very similar. Microstructural analyses employing electron backscatter diffraction were used for comparison of the low carbon steels processed by either technique. Both steels feature very similar grain sizes and misorientation angle distributions. With respect to fatigue life the low carbon steel investigated shows properties similar to ultra-fine grained interstitial-free steel processed by conventional equal channel angular pressing, and thus, the general fatigue behavior can be addressed following the same routines as proposed for interstitial-free steel. In conclusion, the continuously processed material exhibits very promising properties, and thus, equal channel angular pressing-Conform is a promising tool for production of ultra-fine grained steels in a large quantity

  19. The mechanical properties and microstructures of vanadium bearing high strength dual phase steels processed with continuous galvanizing line simulations

    Science.gov (United States)

    Gong, Yu

    microstructure exhibited a somewhat lower strength but much high general and local formabilities. In this thesis, both the physical and mechanical metallurgy of these steels and processes will be discussed. This research has shown that simple compositions and processes can result in DP steels with so-called Generation III properties.

  20. Transport and phosphorylation of choline in higher plant cells. Phosphorus-31 nuclear magnetic resonance studies

    Energy Technology Data Exchange (ETDEWEB)

    Bligny, R.; Foray, M.F.; Roby, C.; Douce, R.

    1989-03-25

    When sycamore cells were suspended in basal medium containing choline, the latter was taken up by the cells very rapidly. A facilitated diffusion system appertained at low concentrations of choline and exhibited Michaelis-Menten kinetics. At higher choline concentrations simple diffusion appeared to be the principal mode of uptake. Addition of choline to the perfusate of compressed sycamore cells monitored by /sup 31/P NMR spectroscopy resulted in a dramatic accumulation of P-choline in the cytoplasmic compartment containing choline kinase and not in the vacuole. The total accumulation of P-choline over a 10-h period exhibited Michaelis-Menten kinetics. During this period, in the absence of Pi in the perfusion medium there was a marked depletion of glucose-6-P, and the cytoplasmic Pi resonance disappeared almost completely. When a threshold of cytoplasmic Pi was attained, the phosphorylation of choline was sustained by the continuous release of Pi from the vacuole although at a much lower rate. However, when 100 microM inorganic phosphate was present in the perfusion medium, externally added Pi was preferentially used to sustain P-choline synthesis. It is clear, therefore, that cytosolic choline kinase associated with a carrier-mediated transport system for choline uptake appeared as effective systems for continuously trapping cytoplasmic Pi including vacuolar Pi entering the cytoplasm.

  1. Follow-up at the corrected age of 24 months of preterm newborns receiving continuous infusion of fentanyl for pain control during mechanical ventilation.

    Science.gov (United States)

    Ancora, Gina; Lago, Paola; Garetti, Elisabetta; Pirelli, Anna; Merazzi, Daniele; Pierantoni, Luca; Ferrari, Fabrizio; Faldella, Giacomo

    2017-05-01

    The neurodevelopmental impact of fentanyl given to preterm newborns for pain control is still unknown. The aim of this study was to assess the neurodevelopmental impact of 2 regimens of fentanyl administration by a prospective follow-up evaluation. In our previous multicenter, double-blind, randomized controlled trial, 131 mechanically ventilated newborns (gestational age ≤32 weeks) were randomized to fentanyl (continuous infusion of fentanyl + open label boluses of fentanyl) or placebo (continuous infusion of placebo + open label boluses of fentanyl). Infant development was evaluated using Griffiths Mental Developmental Scales (Griffiths, 1996) until 24 months of corrected age by trained psychologists who were not aware of the group allocation. 106/131 infants survived at discharge; 3 died after discharge, 25 were lost to follow-up (12 in the fentanyl and 13 in the placebo group). Seventy-eight patients were evaluated at 2 years of corrected age. Children in the fentanyl group, compared with those in the placebo group, obtained significantly lower Griffiths general developmental quotient (mean [SD]: 89.95 [13.64] vs 97.18 [12.72], P = 0.024) together with the scores on the eye-hand coordination (mean [SD]: 89.09 [12.13] vs 99.19 [13.19], P = 0.002) and performance skills (mean [SD]: 79.71 [15.80] vs 90.09 [15.28], P = 0.009) scales. After adjustment for clinical confounders (gestational age, CRIB score, and sex) only eye-hand co-ordination was associated with fentanyl infusion. This study demonstrates that continuous infusion of fentanyl in very preterm infants, given at 1 mcg·kg·h during mechanical ventilation, is associated with a significant decrease in eye and hand co-ordination skills. Longer follow-up is needed to evaluate the impact on future motor, cognitive, and behavioral functions.

  2. Static and dynamic mechanical properties of alkali treated unidirectional continuous Palmyra Palm Leaf Stalk Fiber/jute fiber reinforced hybrid polyester composites

    International Nuclear Information System (INIS)

    Shanmugam, D.; Thiruchitrambalam, M.

    2013-01-01

    Highlights: • New type of hybrid composite with Palmyra Palm Leaf Stalk Fibers (PPLSF) and jute. • Composites fabricated with continuous, unidirectional fibers. • Alkali treatment and hybridizing jute imparted good static and dynamic properties. • Properties are comparable with well know natural/glass fiber composites. • New hybrid composite can be an alternative in place of synthetic fiber composites. - Abstract: Alkali treated continuous Palmyra Palm Leaf Stalk Fiber (PPLSF) and jute fibers were used as reinforcement in unsaturated polyester matrix and their static and dynamic mechanical properties were evaluated. Continuous PPLSF and jute fibers were aligned unidirectionally in bi-layer arrangement and the hybrid composites were fabricated by compression molding process. Positive hybrid effect was observed for the composites due to hybridization. Increasing jute fiber loading showed a considerable increase in tensile and flexural properties of the hybrid composites as compared to treated PPLSF composites. Scanning Electron microscopy (SEM) of the fractured surfaces showed the nature of fiber/matrix interface. The impact strength of the hybrid composites were observed to be less compared to pure PPLSF composites. Addition of jute fibers to PPLSF and alkali treatment of the fibers has enhanced the storage and loss modulus of the hybrid composites. A positive shift of Tan δ peaks to higher temperature and reduction in the peak height of the composites was also observed. The composites with higher jute loading showed maximum damping behavior. Overall the hybridization was found to be efficient showing increased static and dynamic mechanical properties. A comparative study of properties of this hybrid composite with other hybrids made out of using natural/glass fibers is elaborated. Hybridization of alkali treated jute and PPLSF has resulted in enhanced properties which are comparable with other natural/glass fiber composites thus increasing the scope of

  3. Chemomics-based marker compounds mining and mimetic processing for exploring chemical mechanisms in traditional processing of herbal medicines, a continuous study on Rehmanniae Radix.

    Science.gov (United States)

    Zhou, Li; Xu, Jin-Di; Zhou, Shan-Shan; Shen, Hong; Mao, Qian; Kong, Ming; Zou, Ye-Ting; Xu, Ya-Yun; Xu, Jun; Li, Song-Lin

    2017-12-29

    Exploring processing chemistry, in particular the chemical transformation mechanisms involved, is a key step to elucidate the scientific basis in traditional processing of herbal medicines. Previously, taking Rehmanniae Radix (RR) as a case study, the holistic chemome (secondary metabolome and glycome) difference between raw and processed RR was revealed by integrating hyphenated chromatographic techniques-based targeted glycomics and untargeted metabolomics. Nevertheless, the complex chemical transformation mechanisms underpinning the holistic chemome variation in RR processing remain to be extensively clarified. As a continuous study, here a novel strategy by combining chemomics-based marker compounds mining and mimetic processing is proposed for further exploring the chemical mechanisms involved in herbal processing. First, the differential marker compounds between raw and processed herbs were rapidly discovered by untargeted chemomics-based mining approach through multivariate statistical analysis of the chemome data obtained by integrated metabolomics and glycomics analysis. Second, the marker compounds were mimetically processed under the simulated physicochemical conditions as in the herb processing, and the final reaction products were chemically characterized by targeted chemomics-based mining approach. Third, the main chemical transformation mechanisms involved were clarified by linking up the original marker compounds and their mimetic processing products. Using this strategy, a set of differential marker compounds including saccharides, glycosides and furfurals in raw and processed RR was rapidly found, and the major chemical mechanisms involved in RR processing were elucidated as stepwise transformations of saccharides (polysaccharides, oligosaccharides and monosaccharides) and glycosides (iridoid glycosides and phenethylalcohol glycosides) into furfurals (glycosylated/non-glycosylated hydroxymethylfurfurals) by deglycosylation and/or dehydration. The

  4. Rethinking fundamentals of enzyme action.

    Science.gov (United States)

    Northrop, D B

    1999-01-01

    Despite certain limitations, investigators continue to gainfully employ concepts rooted in steady-state kinetics in efforts to draw mechanistically relevant inferences about enzyme catalysis. By reconsidering steady-state enzyme kinetic behavior, this review develops ideas that allow one to arrive at the following new definitions: (a) V/K, the ratio of the maximal initial velocity divided by the Michaelis-Menten constant, is the apparent rate constant for the capture of substrate into enzyme complexes that are destined to yield product(s) at some later point in time; (b) the maximal velocity V is the apparent rate constant for the release of substrate from captured complexes in the form of free product(s); and (c) the Michaelis-Menten constant K is the ratio of the apparent rate constants for release and capture. The physiologic significance of V/K is also explored to illuminate aspects of antibiotic resistance, the concept of "perfection" in enzyme catalysis, and catalytic proficiency. The conceptual basis of congruent thermodynamic cycles is also considered in an attempt to achieve an unambiguous way for comparing an enzyme-catalyzed reaction with its uncatalyzed reference reaction. Such efforts promise a deeper understanding of the origins of catalytic power, as it relates to stabilization of the reactant ground state, stabilization of the transition state, and reciprocal stabilizations of ground and transition states.

  5. Fock space, symbolic algebra, and analytical solutions for small stochastic systems.

    Science.gov (United States)

    Santos, Fernando A N; Gadêlha, Hermes; Gaffney, Eamonn A

    2015-12-01

    Randomness is ubiquitous in nature. From single-molecule biochemical reactions to macroscale biological systems, stochasticity permeates individual interactions and often regulates emergent properties of the system. While such systems are regularly studied from a modeling viewpoint using stochastic simulation algorithms, numerous potential analytical tools can be inherited from statistical and quantum physics, replacing randomness due to quantum fluctuations with low-copy-number stochasticity. Nevertheless, classical studies remained limited to the abstract level, demonstrating a more general applicability and equivalence between systems in physics and biology rather than exploiting the physics tools to study biological systems. Here the Fock space representation, used in quantum mechanics, is combined with the symbolic algebra of creation and annihilation operators to consider explicit solutions for the chemical master equations describing small, well-mixed, biochemical, or biological systems. This is illustrated with an exact solution for a Michaelis-Menten single enzyme interacting with limited substrate, including a consideration of very short time scales, which emphasizes when stiffness is present even for small copy numbers. Furthermore, we present a general matrix representation for Michaelis-Menten kinetics with an arbitrary number of enzymes and substrates that, following diagonalization, leads to the solution of this ubiquitous, nonlinear enzyme kinetics problem. For this, a flexible symbolic maple code is provided, demonstrating the prospective advantages of this framework compared to stochastic simulation algorithms. This further highlights the possibilities for analytically based studies of stochastic systems in biology and chemistry using tools from theoretical quantum physics.

  6. Focal mechanisms and inter-event times of low-frequency earthquakes reveal quasi-continuous deformation and triggered slow slip on the deep Alpine Fault

    Science.gov (United States)

    Baratin, Laura-May; Chamberlain, Calum J.; Townend, John; Savage, Martha K.

    2018-02-01

    Characterising the seismicity associated with slow deformation in the vicinity of the Alpine Fault may provide constraints on the stresses acting on a major transpressive margin prior to an anticipated great (≥M8) earthquake. Here, we use recently detected tremor and low-frequency earthquakes (LFEs) to examine how slow tectonic deformation is loading the Alpine Fault late in its typical ∼300-yr seismic cycle. We analyse a continuous seismic dataset recorded between 2009 and 2016 using a network of 10-13 short-period seismometers, the Southern Alps Microearthquake Borehole Array. Fourteen primary LFE templates are used in an iterative matched-filter and stacking routine, allowing the detection of similar signals corresponding to LFE families sharing common locations. This yields an 8-yr catalogue containing 10,000 LFEs that are combined for each of the 14 LFE families using phase-weighted stacking to produce signals with the highest possible signal-to-noise ratios. We show that LFEs occur almost continuously during the 8-yr study period and highlight two types of LFE distributions: (1) discrete behaviour with an inter-event time exceeding 2 min; (2) burst-like behaviour with an inter-event time below 2 min. We interpret the discrete events as small-scale frequent deformation on the deep extent of the Alpine Fault and LFE bursts (corresponding in most cases to known episodes of tremor or large regional earthquakes) as brief periods of increased slip activity indicative of slow slip. We compute improved non-linear earthquake locations using a 3-D velocity model. LFEs occur below the seismogenic zone at depths of 17-42 km, on or near the hypothesised deep extent of the Alpine Fault. The first estimates of LFE focal mechanisms associated with continental faulting, in conjunction with recurrence intervals, are consistent with quasi-continuous shear faulting on the deep extent of the Alpine Fault.

  7. Supertoughened Biobased Poly(lactic acid)-Epoxidized Natural Rubber Thermoplastic Vulcanizates: Fabrication, Co-continuous Phase Structure, Interfacial in Situ Compatibilization, and Toughening Mechanism.

    Science.gov (United States)

    Wang, Youhong; Chen, Kunling; Xu, Chuanhui; Chen, Yukun

    2015-09-10

    In the presence of dicumyl peroxide (DCP), biobased thermoplastic vulcanizates (TPVs) composed of poly(lactic acid) (PLA) and epoxidized natural rubber (ENR) were prepared through dynamic vulcanization. Interfacial in situ compatibilization between PLA and ENR phases was confirmed by Fourier transform infrared spectroscopy (FT-IR). A novel "sea-sea" co-continuous phase in the PLA/ENR TPVs was observed through scanning electron microscopy (SEM) and differed from the typical "sea-island" morphology that cross-linked rubber particles dispersed in plastic matrix. A sharp, brittle-ductile transition occurred with 40 wt % of ENR, showing a significantly improved impact strength of 47 kJ/m(2), nearly 15 times that of the neat PLA and 2.6 times that of the simple blend with the same PLA/ENR ratio. Gel permeation chromatography (GPC) and dynamic mechanical analysis (DMA) results suggested that a certain amount of DCP was consumed in the PLA phase, causing a slight cross-linking or branching of PLA molecules. the effects of various DCP contents on the impact property were investigated. The toughening mechanism under impact testing was researched, and the influence factors for toughening were discussed.

  8. Comparison of continuous compression with regular ventilations versus 30:2 compressions-ventilations strategy during mechanical cardiopulmonary resuscitation in a porcine model of cardiac arrest.

    Science.gov (United States)

    Yang, Zhengfei; Liu, Qingyu; Zheng, Guanghui; Liu, Zhifeng; Jiang, Longyuan; Lin, Qing; Chen, Rui; Tang, Wanchun

    2017-09-01

    A compression-ventilation (C:V) ratio of 30:2 is recommended for adult cardiopulmonary resuscitation (CPR) by the current American Heart Association (AHA) guidelines. However, continuous chest compression (CCC) is an alternative strategy for CPR that minimizes interruption especially when an advanced airway exists. In this study, we investigated the effects of 30:2 mechanical CPR when compared with CCC in combination with regular ventilation in a porcine model. Sixteen male domestic pigs weighing 39±2 kg were utilized. Ventricular fibrillation was induced and untreated for 7 min. The animals were then randomly assigned to receive CCC combined with regular ventilation (CCC group) or 30:2 CPR (VC group). Mechanical chest compression was implemented with a miniaturized mechanical chest compressor. At the same time of beginning of precordial compression, the animals were mechanically ventilated at a rate of 10 breaths-per-minute in the CCC group or with a 30:2 C:V ratio in the VC group. Defibrillation was delivered by a single 150 J shock after 5 min of CPR. If failed to resuscitation, CPR was resumed for 2 min before the next shock. The protocol was stopped if successful resuscitation or at a total of 15 min. The resuscitated animals were observed for 72 h. Coronary perfusion pressure, end-tidal carbon dioxide and carotid blood flow in the VC group were similar to those achieved in the CCC group during CPR. No significant differences were observed in arterial blood gas parameters between two groups at baseline, VF 6 min, CPR 4 min and 30, 120 and 360 min post-resuscitation. Although extravascular lung water index of both groups significantly increased after resuscitation, no distinct difference was found between CCC and VC groups. All animals were successfully resuscitated and survived for 72 h with favorable neurologic outcomes in both groups. However, obviously more numbers of rib fracture were observed in CCC animals in comparison with VC animals. There was no

  9. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  10. Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies.

    Science.gov (United States)

    Rahman, N K; Kamaruddin, A H; Uzir, M H

    2011-08-01

    The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.

  11. Outcomes of pediatric patients supported with continuous-flow ventricular assist devices: A report from the Pediatric Interagency Registry for Mechanical Circulatory Support (PediMACS).

    Science.gov (United States)

    Rossano, Joseph W; Lorts, Angela; VanderPluym, Christina J; Jeewa, Aamir; Guleserian, Kristine J; Bleiweis, Mark S; Reinhartz, Olaf; Blume, Elizabeth D; Rosenthal, David N; Naftel, David C; Cantor, Ryan S; Kirklin, James K

    2016-05-01

    Continuous-flow (CF) ventricular assist devices (VADs) have largely replaced pulsatile-flow VADs in adult patients. However, there are few data on CF VADs among pediatric patients. In this study we aimed to describe the overall use, patients' characteristics and outcomes of CF VADs in this population. The Pediatric Interagency Registry for Mechanical Circulatory Support (PediMACS) is a national registry for U.S. Food and Drug Adminstration (FDA)-approved VADs in patients <19 years of age. Patients undergoing placement of durable CF VADs between September 2012 and June 2015 were included and outcomes were compared with those of adults from the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). CF VADs were implanted in 109 patients at 35 hospitals. The median age at implantation was 15 years (2.8 to 18.9 years) and median weight was 62 kg (range 16 to 141 kg). The underlying disease was cardiomyopathy in 89 (82%) patients. The INTERMACS level at time of implant was Level 1 in 20 (19%), Level 2 in 64 (61%) and Levels 3 to 7 in 21 (20%) patients. Most were implanted as LVADs (n = 102, 94%). Median duration of support was 2.3 months (range <1 day to 28 months). Serious adverse event rates were low, including neurologic dysfunction (early event rate 4.1 per 100 patient-months with 2 late events). Competing outcomes analysis at 6 months post-implant indicated 61% transplanted, 31% alive with device in place and 8% death before transplant. These outcomes compared favorably with the 3,894 adults supported with CF VADs as a bridge to transplant. CF VADs are commonly utilized in older children and adolescents, with excellent survival rates. Further study is needed to understand impact of patient and device characteristics on outcomes in pediatric patients. Copyright © 2016 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

  12. Continuous auditing & continuous monitoring : Continuous value?

    NARCIS (Netherlands)

    van Hillo, Rutger; Weigand, Hans; Espana, S; Ralyte, J; Souveyet, C

    2016-01-01

    Advancements in information technology, new laws and regulations and rapidly changing business conditions have led to a need for more timely and ongoing assurance with effectively working controls. Continuous Auditing (CA) and Continuous Monitoring (CM) technologies have made this possible by

  13. Effects of Hot-Hydrostatic Canned Extrusion on the Stock Utilization, Microstructure and Mechanical Properties of TiBw/TC4 Composites with Quasi-Continuous Network.

    Science.gov (United States)

    Feng, Yangju; Li, Bing; Cui, Guorong; Zhang, Wencong

    2017-10-25

    In-situ TiB whisker-reinforced Ti-6Al-4V (TC4) titanium matrix composites (TiBw/TC4) with quasi-continuous networks were successfully fabricated by vacuum hot-pressing sintering. The effects of the hot-hydrostatic canned extrusion on stock utilization, microstructure and mechanical properties of the TiBw/TC4 composites were investigated. It was satisfactory that the utilization of composites could be obviously improved by canned extrusion compared to that extruded without canned extrusion. The microstructure results showed that after canned extrusion the grain was refined and the TiB whiskers were distributed from a random array state to a state in which the whiskers were distributed along the extrusion direction. The properties testing results revealed that the tensile strength, the hardness and the ductility of the composites all significantly improved after extrusion due to the grain refinement and orientation of the TiB whisker caused by extrusion. Tensile fracture results showed that when the TiB whiskers were randomly distributed only part of them played a role in strengthening the matrix during the deformation process (as-sintered composites), while when the TiB whiskers were oriented all whiskers could strengthen the matrix during the tensile testing process (as-extruded composites).

  14. Variable-Frequency Ultrasonic Treatment on Microstructure and Mechanical Properties of ZK60 Alloy during Large Diameter Semi-Continuous Casting

    Directory of Open Access Journals (Sweden)

    Xingrui Chen

    2017-05-01

    Full Text Available Traditional fixed-frequency ultrasonic technology and a variable-frequency ultrasonic technology were applied to refine the as-cast microstructure and improve the mechanical properties of a ZK60 (Mg–Zn–Zr alloy during large diameter semi-continuous casting. The acoustic field propagation was obtained by numerical simulation. The microstructure of the as-cast samples was characterized by optical and scanning electron microscopy. The variable-frequency ultrasonic technology shows its outstanding ability in grain refinement compared with traditional fixed-ultrasonic technology. The variable-frequency acoustic field promoted the formation of small α-Mg globular grains and changed the distribution and morphology of β-phases throughout the castings. Ultimate tensile strength and elongation are increased to 280 MPa and 8.9%, respectively, which are 19.1% and 45.9% higher than the values obtained from billets without ultrasonic treatment and are 11.6% and 18.7% higher than fixed-frequency ultrasound treated billets. Different refinement efficiencies appear in different districts of billets attributed to the sound attenuation in melt. The variable-frequency acoustic field improves the refinement effect by enhancing cavitation-enhanced heterogeneous nucleation and dendrite fragmentation effects.

  15. Mechanical and microstructural characteristics of meat doughs, either heated by a continuous process in a radio-frequency field or conventionally in a waterbath.

    Science.gov (United States)

    van Roon, P S; Houben, J H; Koolmees, P A; van Vliet, T; Krol, B

    1994-01-01

    Meat doughs, all having the same chemical composition, were pasteurised to a comparable heat intensity (calculated as Cook values: target level of 5 min at 100°C): (i) while flowing through a glass tube (inner diameter 50 mm) mounted in a special radio-frequency (27 MHz) heating section; (ii) after flowing unheated through the glass tube at the same rate and heated in a waterbath; and (iii) after sampling immediately after the pump and heated in a waterbath. The cooked products were sampled in the core and at the rim of the product for rheological (oscillation and uniaxial compression tests at small strain), fracture measurements (uniaxial compression tests at high strain) and microstructural evaluation (light microscopy and video image analysis). Additional core samples were used for a sensory evaluation (triangle tests) of the texture of the differently processed doughs. The fast heating rate (25-30 K/min) at a mass flow of the dough of 100 kg/h (mean velocity 0.014 m/s) during dielectrical pasteurisation affected the mechanical character, the microstructure and the triangle test results of core samples from the sausages, compared to heating in a waterbath. Flow of the unheated dough through the tube of the continuous processing equipment, followed by heating in a waterbath, had little effect on the results of the mechanical tests, the microscopical evaluation and the triangle tests. The radio-frequency heated products had both higher storage and loss moduli (were more firm), fractured at higher stress values and were considered more firm in the sensory evaluation. The microstructure of dielectrically heated versus other samples displayed a more open structure of the protein matrix with larger irregularly shaped fat particles that were surrounded by relatively thin and compact protein bridges. The effects of flow and heating method on the behaviour of rim samples were very similar to their effects on the core of the products. A comparison of the mechanical

  16. [Effect of continuous aspiration of subglottic secretions on the prevention of ventilator-associated pneumonia in mechanically ventilated patients: a prospective, randomized, controlled clinical trial].

    Science.gov (United States)

    Yang, Cong-shan; Qiu, Hai-bo; Zhu, Yan-ping; Huang, Ying-zi; Xu, Xiao-ting; Gao, Liang

    2008-08-01

    To evaluate the effect of continuous aspiration of subglottic secretions (CASS) on the prevention of ventilator-associated pneumonia (VAP) in mechanically ventilated patients. Patients ventilated mechanically at the ICU from October, 2004 to April, 2006 were randomly divided into 2 groups: one group received CASS and the other did not (NASS group). CASS was performed immediately after admission for patients in the CASS group. The diagnosis of VAP was made based on clinical presentations, and the evaluation of VAP was done using simplified version of the clinical pulmonary infection score (CPIS). The general status of the patients, days of ventilated treatment, the volume of daily aspirated subglottic secretions, the morbidity and timing of VAP, days of stay in ICU and mortality within 28 days of hospitalization were recorded. One hundred and one patients were included in the study. There were 48 patients in the CASS group who were treated with mechanical ventilation more than 48 hours, and 43 patients in the NASS group. There was no significant difference in the general status of the patients and days of ventilation between 2 groups with the averaged score of APACHE II being 20.8 +/- 6.1. The average of CPIS was of 5.6 +/- 1.0 when VAP was diagnosed. The mean volume of aspirated subglottic secretions within the first 24 hours in the CASS group (n = 48) was (27.2 +/- 21.2) ml. The morbidity of VAP in the CASS and the NASS groups was 25.0% and 46.5% respectively (P = 0.032), and the length of time before the onset of VAP in these 2 groups was (7.3 +/- 4.2) days and (5.1 +/- 3.0) days respectively (P = 0.100). There was a significant increase in the percentage of gram-positive cocci from the lower respiratory tracts in the NASS group compared with that in the CASS group (P = 0.004). In the CASS group, the volume of the first daily aspirated subglottic secretions in patients with VAP was significantly less than that in patients without VAP (P = 0.006). The morbidity of

  17. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  18. Effect of friction time on mechanical and metallurgical properties of continuous drive friction welded Ti6Al4V/SUS321 joints

    International Nuclear Information System (INIS)

    Li, Peng; Li, Jinglong; Salman, Muhammad; Liang, Li; Xiong, Jiangtao; Zhang, Fusheng

    2014-01-01

    Highlights: • The effect of friction time on the microstructure and joint strength was studied. • The fit of burn-off lengths at different times yields a simple equation. • The longer friction time leads to oversized flash in Ti6Al4V side and overgrown IMCs. • An IMZ with width less than 3 μm is beneficial to make a strong metallurgical bond. • The average strength of 560 MPa is obtained and higher than ever reported results. - Abstract: Dissimilar joint of Ti6Al4V titanium alloy and SUS321 stainless steel was fabricated by continuous drive friction welding. The effect of friction time on the mechanical properties was evaluated by hardness measurement and tensile test, while the interfacial microstructure and fracture morphologies were analyzed by scanning electron microscope, energy dispersive spectroscope and X-ray Diffraction. The results show that the tensile strength increases with friction time under the experimental conditions. And the maximum average strength 560 MPa, which is 90.3% of the SUS321 base metal, is achieved at a friction time of 4 s. For all samples, studied fracture occurred along the joint interface, where intermetallic compounds like FeTi, Fe 2 Ti, Ni 3 (Al, Ti) and Fe 3 Ti 3 O and many other phases were formed among elements from the two base metals. The width of intermetallic compounds zone increases with friction time up to 3 μm, below which it is beneficial to make a strong metallurgical bond. However, the longer friction time leads to oversized flash on the Ti6Al4V side and overgrown intermetallic compounds. Finally the optimized friction time was discussed to be in the range of 2–4 s, under which the sound joint with good reproducibility can be expected

  19. Continuous Problem of Function Continuity

    Science.gov (United States)

    Jayakody, Gaya; Zazkis, Rina

    2015-01-01

    We examine different definitions presented in textbooks and other mathematical sources for "continuity of a function at a point" and "continuous function" in the context of introductory level Calculus. We then identify problematic issues related to definitions of continuity and discontinuity: inconsistency and absence of…

  20. Secondary Inorganic Soluble Aerosol in Hong Kong: Continuous Measurements, Formation Mechanism Discussion and Improvement of an Observation-Based Model to Study Control Strategies

    Science.gov (United States)

    Xue, Jian

    Work in this thesis focuses on half-hourly or hourly measurements of PM2.5 secondary inorganic aerosols (SIA) in two locations in Hong Kong (HK) using a continuous system, PILS (Particle-into-Liquid System) coupled to two ion chromatographs. The high-resolution data sets allow the examination of SIA temporal dynamics in the scale of hours that the filter-based approach is incapable of providing. (1) Impacts of local emissions, regional transports and their interactions on chemical composition and concentrations of PM2.5 SIA and other ionic species were investigated at the Hong Kong University of Science and Technology (HKUST), a receptor site, under three synoptic conditions. (2) Chemical compositions and size characteristics of ionic species were investigated at Tung Chung, a new town area located in the Southwest part of HK. The sampling period was from 17 to 26 December 2009, covering both normal conditions and an aerosol episode. The three major secondary inorganic ions, SO42, NH4+ and NO 3-, accounted for 47 +/- 6% of PM2.5 mass. Further examination of size characteristics of NO3 - shows that fine mode NO3- is more likely to occur in environments when the fine particles are less acidic and the sea-salt aerosol contributions are low. (3) The ionic chemical composition of PM2.5 and meteorological parameters (e.g., temperature, RH) obtained at the HKUST site under all three different synoptic conditions are input into Aerosol Inorganic Model (AIM-III) for estimation of in situ pH through calculation of H+ amount and aerosol liquid water content (LWC). The second part of this thesis work is to improve an observation-based model (OBAMAP) for SIA, which was first developed by Dr. Zibing Yuan (2006) to evaluate the sensitivity of formation of nitrate ad sulfate to changes in the emissions of their precursors (i.e., NOx, SO2, and VOCs). The improvement work includes incorporating updated chemical mechanisms, thermodynamic equilibrium for gas-aerosol phase

  1. Business continuity

    International Nuclear Information System (INIS)

    Breunhoelder, Gert

    2002-01-01

    This presentation deals with the following keypoints: Information Technology (IT) Business Continuity and Recovery essential for any business; lessons learned after Sept. 11 event; Detailed planning, redundancy and testing being the key elements for probability estimation of disasters

  2. Continuous tokamaks

    International Nuclear Information System (INIS)

    Peng, Y.K.M.

    1978-04-01

    A tokamak configuration is proposed that permits the rapid replacement of a plasma discharge in a ''burn'' chamber by another one in a time scale much shorter than the elementary thermal time constant of the chamber first wall. With respect to the chamber, the effective duty cycle factor can thus be made arbitrarily close to unity minimizing the cyclic thermal stress in the first wall. At least one plasma discharge always exists in the new tokamak configuration, hence, a continuous tokamak. By incorporating adiabatic toroidal compression, configurations of continuous tokamak compressors are introduced. To operate continuous tokamaks, it is necessary to introduce the concept of mixed poloidal field coils, which spatially groups all the poloidal field coils into three sets, all contributing simultaneously to inducing the plasma current and maintaining the proper plasma shape and position. Preliminary numerical calculations of axisymmetric MHD equilibria in continuous tokamaks indicate the feasibility of their continued plasma operation. Advanced concepts of continuous tokamaks to reduce the topological complexity and to allow the burn plasma aspect ratio to decrease for increased beta are then suggested

  3. Continuous Dropout.

    Science.gov (United States)

    Shen, Xu; Tian, Xinmei; Liu, Tongliang; Xu, Fang; Tao, Dacheng

    2017-10-03

    Dropout has been proven to be an effective algorithm for training robust deep networks because of its ability to prevent overfitting by avoiding the co-adaptation of feature detectors. Current explanations of dropout include bagging, naive Bayes, regularization, and sex in evolution. According to the activation patterns of neurons in the human brain, when faced with different situations, the firing rates of neurons are random and continuous, not binary as current dropout does. Inspired by this phenomenon, we extend the traditional binary dropout to continuous dropout. On the one hand, continuous dropout is considerably closer to the activation characteristics of neurons in the human brain than traditional binary dropout. On the other hand, we demonstrate that continuous dropout has the property of avoiding the co-adaptation of feature detectors, which suggests that we can extract more independent feature detectors for model averaging in the test stage. We introduce the proposed continuous dropout to a feedforward neural network and comprehensively compare it with binary dropout, adaptive dropout, and DropConnect on Modified National Institute of Standards and Technology, Canadian Institute for Advanced Research-10, Street View House Numbers, NORB, and ImageNet large scale visual recognition competition-12. Thorough experiments demonstrate that our method performs better in preventing the co-adaptation of feature detectors and improves test performance.

  4. Continuity theory

    CERN Document Server

    Nel, Louis

    2016-01-01

    This book presents a detailed, self-contained theory of continuous mappings. It is mainly addressed to students who have already studied these mappings in the setting of metric spaces, as well as multidimensional differential calculus. The needed background facts about sets, metric spaces and linear algebra are developed in detail, so as to provide a seamless transition between students' previous studies and new material. In view of its many novel features, this book will be of interest also to mature readers who have studied continuous mappings from the subject's classical texts and wish to become acquainted with a new approach. The theory of continuous mappings serves as infrastructure for more specialized mathematical theories like differential equations, integral equations, operator theory, dynamical systems, global analysis, topological groups, topological rings and many more. In light of the centrality of the topic, a book of this kind fits a variety of applications, especially those that contribute to ...

  5. Continuation calculus

    NARCIS (Netherlands)

    Geron, B.; Geuvers, J.H.; de'Liguoro, U.; Saurin, A.

    2013-01-01

    Programs with control are usually modeled using lambda calculus extended with control operators. Instead of modifying lambda calculus, we consider a different model of computation. We introduce continuation calculus, or CC, a deterministic model of computation that is evaluated using only head

  6. Continuation calculus

    Directory of Open Access Journals (Sweden)

    Bram Geron

    2013-09-01

    Full Text Available Programs with control are usually modeled using lambda calculus extended with control operators. Instead of modifying lambda calculus, we consider a different model of computation. We introduce continuation calculus, or CC, a deterministic model of computation that is evaluated using only head reduction, and argue that it is suitable for modeling programs with control. It is demonstrated how to define programs, specify them, and prove them correct. This is shown in detail by presenting in CC a list multiplication program that prematurely returns when it encounters a zero. The correctness proof includes termination of the program. In continuation calculus we can model both call-by-name and call-by-value. In addition, call-by-name functions can be applied to call-by-value results, and conversely.

  7. Kinetics of the norepinephrine analog [76Br]-meta-bromobenzylguanidine in isolated working rat heart

    International Nuclear Information System (INIS)

    Raffel, David; Loc'h, Christian; Mardon, Karine; Maziere, Bernard; Syrota, Andre

    1998-01-01

    A related set of kinetic studies of the norepinephrine analog [ 76 Br]-meta-bromobenzylguanidine (MBBG) were performed with an isolated working rat heart preparation. A series of constant infusion studies over a wide range of MBBG concentrations allowed estimation of the Michaelis-Menten constants for transport by the neuronal norepinephrine transporter (uptake 1 ) and the extraneuronal uptake system (uptake 2 ). Pharmacological blocking studies with inhibitors of uptake 1 , uptake 2 and vesicular uptake were performed to delineate the relative importance of these norepinephrine handling mechanisms on the kinetics of MBBG in the rat heart. Bolus injection studies were done to assess the ability of compartmental modeling techniques to characterize the kinetics of MBBG. These studies demonstrate that MBBG shares many of the same uptake mechanisms as norepinephrine in the rat heart. PET imaging studies with MBBG would be useful for assessing sympathetic nerve status in the living human heart

  8. No-threshold dose-response curves for nongenotoxic chemicals: Findings and applications for risk assessment

    International Nuclear Information System (INIS)

    Sheehan, Daniel M.

    2006-01-01

    We tested the hypothesis that no threshold exists when estradiol acts through the same mechanism as an active endogenous estrogen. A Michaelis-Menten (MM) equation accounting for response saturation, background effects, and endogenous estrogen level fit a turtle sex-reversal data set with no threshold and estimated the endogenous dose. Additionally, 31 diverse literature dose-response data sets were analyzed by adding a term for nonhormonal background; good fits were obtained but endogenous dose estimations were not significant due to low resolving power. No thresholds were observed. Data sets were plotted using a normalized MM equation; all 178 data points were accommodated on a single graph. Response rates from ∼1% to >95% were well fit. The findings contradict the threshold assumption and low-dose safety. Calculating risk and assuming additivity of effects from multiple chemicals acting through the same mechanism rather than assuming a safe dose for nonthresholded curves is appropriate

  9. Spectral Quasi-Equilibrium Manifold for Chemical Kinetics.

    Science.gov (United States)

    Kooshkbaghi, Mahdi; Frouzakis, Christos E; Boulouchos, Konstantinos; Karlin, Iliya V

    2016-05-26

    The Spectral Quasi-Equilibrium Manifold (SQEM) method is a model reduction technique for chemical kinetics based on entropy maximization under constraints built by the slowest eigenvectors at equilibrium. The method is revisited here and discussed and validated through the Michaelis-Menten kinetic scheme, and the quality of the reduction is related to the temporal evolution and the gap between eigenvalues. SQEM is then applied to detailed reaction mechanisms for the homogeneous combustion of hydrogen, syngas, and methane mixtures with air in adiabatic constant pressure reactors. The system states computed using SQEM are compared with those obtained by direct integration of the detailed mechanism, and good agreement between the reduced and the detailed descriptions is demonstrated. The SQEM reduced model of hydrogen/air combustion is also compared with another similar technique, the Rate-Controlled Constrained-Equilibrium (RCCE). For the same number of representative variables, SQEM is found to provide a more accurate description.

  10. Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source

    Science.gov (United States)

    Wells, R. P.; Ghiorso, W.; Staples, J.; Huang, T. M.; Sannibale, F.; Kramasz, T. D.

    2016-02-01

    A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

  11. Kinetic evaluation of an anaerobic fluidised-bed reactor treating slaughterhouse wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Borja, R. [Consejo Superior de Investigaciones Cientificas, Seville (Spain). Inst. de la Grasa; Banks, C.J.; Zhengjian Wang [Manchester Univ. (United Kingdom). Inst. of Science and Technology

    1995-09-01

    An anaerobic fluidised-bed reactor for purification of slaughterhouse wastewater was modelled as a continuous-flow, completely-mixed homogeneous microbial system, with the feed COD as the limiting-substrate concentration. The average microbial residence time in the reactor was defined in terms of conventional sludge-retention-time. The experimental data obtained indicated that the Michaelis-Menten expression was applicable to a description of substrate utilisation (i.e. COD removal) in the anaerobic fluidised-bed system. The maximum substrate utilisation rate, k, and the Michaelis constant, K{sub s}, were determined to be 1.2/day and 0.039 g/l. The observed biomass yield in the reactor decreased with increasing sludge-retention-time. The specific methane production rate observed was a linear function of the specific substrate-utilisation rate. (Author)

  12. Sufficient conditions for optimality for a mathematical model of drug treatment with pharmacodynamics

    Directory of Open Access Journals (Sweden)

    Maciej Leszczyński

    2017-01-01

    Full Text Available We consider an optimal control problem for a general mathematical model of drug treatment with a single agent. The control represents the concentration of the agent and its effect (pharmacodynamics is modelled by a Hill function (i.e., Michaelis-Menten type kinetics. The aim is to minimize a cost functional consisting of a weighted average related to the state of the system (both at the end and during a fixed therapy horizon and to the total amount of drugs given. The latter is an indirect measure for the side effects of treatment. It is shown that optimal controls are continuous functions of time that change between full or no dose segments with connecting pieces that take values in the interior of the control set. Sufficient conditions for the strong local optimality of an extremal controlled trajectory in terms of the existence of a solution to a piecewise defined Riccati differential equation are given.

  13. Nutrient Removal from Wastewater using Microalgae: A Kinetic Evaluation and Lipid Analysis.

    Science.gov (United States)

    2017-09-15

    The objective of this study was to examine the performance of mixed microalgal bioreactors in treating three differenttypes of wastewaters - kitchen wastewater (KWW), palm oil mill effluent (POME), and pharmaceutical wastewater (PWW) in semi-continuous mode and to analyze the lipid content in the harvested algal biomass. The reactors were monitored for total nitrogen and phosphate removal at eight solid retention times (SRTs) - 2, 4, 6, 8, 10, 12, 14, and 16 days. The nutrient uptake kinetic parameters were quantified using linearized Michaelis-Menten and Monod models at steady-state conditions. The nutrient removal efficiency and lipid production were found to be higher in KWW when compared with the other wastewaters. Saturated fatty acids (C16:0, C18:0, and C18:1) accounted for more than 60% of the algal fatty acids for all the wastewaters. The lipid is, therefore, considered suitable for synthesizing biodiesel.

  14. Modeling of an immobilized lipase tubular reactor for the production of glycerol and fatty acids from oils; Modelado de un reactor tubular de lipasas inmovilizadas para la produccion de glicerol y acidos grasos a partir de aceites

    Energy Technology Data Exchange (ETDEWEB)

    Oddone, S.; Grasselli, M.; Cuellas, A.

    2010-07-01

    Advances in the design of a bioreactor in the fats and oils industry have permitted the hydrolysis of triglycerides in mild conditions and improved productivity while avoiding the formation of unwanted byproducts. The present work develops a mathematical model that describes the hydrolytic activity of a tubular reactor with immobilized lipases for the production of glycerol and fatty acids from the oil trade. Runge Kuttas numerical method of high order has been applied, considering that there is no accumulation of the substratum in the surface of the membrane, where the enzyme is. At the same time, different equations based on the kinetic model of Michaelis Mentens and the Ping-Pong bi-bi mechanism were examined. Experimental data in discontinuous systems are the basis for the development of the quantitative mathematical model that was used to simulate the process computationally. The obtained results allow for optimizing both the operative variables and the economic aspects of industrial processes. (Author)

  15. Correlation analysis of reactivity in the oxidation of some organic diols by tripropylammonium fluorochromate in non-aqueous media

    Directory of Open Access Journals (Sweden)

    S. Sheik Mansoor

    2016-09-01

    Full Text Available The kinetics of oxidation of some organic diols by tripropylammonium fluorochromate (TriPAFC have been studied in dimethylsulfoxide (DMSO. The main product of oxidation is the corresponding hydroxy aldehydes. The reaction is first order with respect to TriPAFC and exhibited Michaelis-Menten type kinetics with respect to organic diols. The reaction is catalyzed by hydrogen ions. The hydrogen ion dependence has the form: kobs = a + b[H+]. Various thermodynamic parameters for the oxidation have been reported and discussed along with the validity of isokinetic relationship. Oxidation of diols was studied in 18 different organic solvents. The rate data are showing satisfactory correlation with Kamlet–Taft solvotochromic parameters (α, β and π∗. A suitable mechanism of oxidation has been proposed.

  16. AIR POLLUTION FROM ANIMAL AND MUNICIPAL WASTEWATER: ASSESSMENT OF PRODUCTION AND RELEASE OF NOXIOUS GASES

    DEFF Research Database (Denmark)

    Dai, Xiaorong

    from animal manure (mixture of urine and feces) by hydrolysis of urinary urea catalyzed by microbial urease present in feces. To better understand the enzymatic process of ammonia formation in manure, experiments based on Michaelis-Menten kinetics were conducted to obtain accurate estimates...... of the kinetic parameters of urease activity of feces and manure from pig and cattle, and to investigate the effects of pH on animal fecal urease by individual ammonium generation rate determination at five pH levels. Investigating the gas production and release mechanisms is important not only for estimating...... characteristics of different types of wastes (e.g., the total nitrogen, total ammoniacal nitrogen, dry matter, and pH) had great influence on the releases of NH3, CO2, H2S, and SO2. The investigation of kinetic parameter showed that the maximum urease activity for pig feces is at around pH 7, while...

  17. Catalytic Activity of μ-Carbido-Dimeric Iron(IV) Octapropylporphyrazinate in the 3,5,7,2',4'-Pentahydroxyflavone Oxidation Reaction with tert-Butyl Hydroperoxide

    Science.gov (United States)

    Tyurin, D. V.; Zaitseva, S. V.; Kudrik, E. V.

    2018-05-01

    It is found for the first time that μ-carbido-dimeric iron(IV) octapropylporphyrazinate displays catalytic activity in the oxidation reaction of natural flavonol morin with tert-butyl hydroperoxide, with the catalyst being stable under conditions of the reaction. The kinetics of this reaction are studied. It is shown the reaction proceeds via tentative formation of a complex between the catalyst and the oxidant, followed by O‒O bond homolytic cleavage. The kinetics of the reaction is described in the coordinates of the Michaelis-Menten equation. A linear dependence of the apparent reaction rate constant on the concentration of the catalyst is observed, testifying to its participation in the limiting reaction step. The equilibrium constants and rates of interaction are found. A mechanism is proposed for the reaction on the basis of the experimental data.

  18. Synthetic, structural mimetics of the β-hairpin flap of HIV-1 protease inhibit enzyme function.

    Science.gov (United States)

    Chauhan, Jay; Chen, Shen-En; Fenstermacher, Katherine J; Naser-Tavakolian, Aurash; Reingewertz, Tali; Salmo, Rosene; Lee, Christian; Williams, Emori; Raje, Mithun; Sundberg, Eric; DeStefano, Jeffrey J; Freire, Ernesto; Fletcher, Steven

    2015-11-01

    Small-molecule mimetics of the β-hairpin flap of HIV-1 protease (HIV-1 PR) were designed based on a 1,4-benzodiazepine scaffold as a strategy to interfere with the flap-flap protein-protein interaction, which functions as a gated mechanism to control access to the active site. Michaelis-Menten kinetics suggested our small-molecules are competitive inhibitors, which indicates the mode of inhibition is through binding the active site or sterically blocking access to the active site and preventing flap closure, as designed. More generally, a new bioactive scaffold for HIV-1PR inhibition has been discovered, with the most potent compound inhibiting the protease with a modest K(i) of 11 μM. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Electrochemical treatment of 2, 4-dichlorophenol using a nanostructured 3D-porous Ti/Sb-SnO2-Gr anode: Reaction kinetics, mechanism, and continuous operation.

    Science.gov (United States)

    Asim, Sumreen; Zhu, Yunqing; Batool, Aisha; Hailili, Reshalaiti; Luo, Jianmin; Wang, Yuanhao; Wang, Chuanyi

    2017-10-01

    2, 4-dichlorophenol (2, 4-DCP) is considered to be a highly toxic, mutagenic, and possibly carcinogenic pollutant. This study is focused on the electrochemical oxidation of 2, 4-DCP on nanostructured 3D-porous Ti/Sb-SnO 2 -Gr anodes, with the aim of presenting a comprehensive elucidation of mineralization process through the investigation of influential kinetics, the reactivity of hydroxyl radical's and analysis of intermediates. High efficiency was achieved at pH of 3 using Na 2 SO 4 electrolytes at a current density of 30 mA cm -2 . Under the optimized conditions, a maximum removal of 2, 4-DCP of up to 99.9% was reached, whereas a TOC removal of 81% was recorded with the lowest EC TOC (0.49 kW h g -1 ) within 40 min of electrolysis. To explore the stability of the 3D-Ti/Sb-SnO 2 -Gr electrodes, a continuous electrochemical operation was established, and the consistent mineralization results indicated the effectiveness of the 3D-Ti/Sb-SnO 2 -Gr system concerning its durability and practical utilization. EPR studies demonstrated the abundant generation of OH radicals on 3D-Ti/Sb-SnO 2 -Gr, resulting in fast recalcitrant pollutant incineration. From dechlorination and the reactivity of the OH radicals, several intermediates including six cyclic byproducts and three aliphatic carboxylic acids were detected, and two possible degradation pathways were proposed that justify the complete mineralization of 2, 4-DCP. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Effect of Continuous Galvanizing Heat Treatments on the Microstructure and Mechanical Properties of High Al-Low Si Transformation Induced Plasticity Steels

    Science.gov (United States)

    Bellhouse, E. M.; McDermid, J. R.

    2010-02-01

    Heat treatments were performed using an isothermal bainitic transformation (IBT) temperature compatible with continuous hot-dip galvanizing on two high Al-low Si transformation induced plasticity (TRIP)-assisted steels. Both steels had 0.2 wt pct C and 1.5 wt pct Mn; one had 1.5 wt pct Al and the other had 1 wt pct Al and 0.5 wt pct Si. Two different intercritical annealing (IA) temperatures were used, resulting in intercritical microstructures of 50 pct ferrite (α)-50 pct austenite (γ) and 65 pct α-35 pct γ. Using the IBT temperature of 465 °C, five IBT times were tested: 4, 30, 60, 90, and 120 seconds. Increasing the IBT time resulted in a decrease in the ultimate tensile strength (UTS) and an increase in the uniform elongation, yield strength, and yield point elongation. The uniform elongation was higher when using the 50 pct α-50 pct γ IA temperature when compared to the 65 pct α-35 pct γ IA temperature. The best combinations of strength and ductility and their corresponding heat treatments were as follows: a tensile strength of 895 MPa and uniform elongation of 0.26 for the 1.5 pct Al TRIP steel at the 50 pct γ IA temperature and 90-second IBT time; a tensile strength of 880 MPa and uniform elongation of 0.27 for the 1.5 pct Al TRIP steel at the 50 pct γ IA temperature and 120-second IBT time; and a tensile strength of 1009 MPa and uniform elongation of 0.22 for the 1 pct Al-0.5 pct Si TRIP steel at the 50 pct γ IA temperature and 120-second IBT time.

  1. Assessment of 17α-ethinylestradiol effects and underlying mechanisms in a continuous, multigeneration exposure of the Chinese rare minnow (Gobiocypris rarus)

    International Nuclear Information System (INIS)

    Zha Jinmiao; Sun Liwei; Zhou Yiqi; Spear, Philip A.; Ma, Mei; Wang Zijian

    2008-01-01

    17α-Ethinylestradiol (EE 2 ) is a synthetic estrogen used primarily in birth control pills and in hormone replacement therapy. Owing to its occurrence in surface waters at concentrations frequently greater than 1 ng/l and its projected future use, EE 2 is expected to pose a significant risk to aquatic organisms. This study was conducted to obtain long-term exposure data necessary for the establishment of water quality criteria and to investigate mechanisms associated with toxic effects. In a multigeneration experiment, Chinese rare minnows (Gobiocypris rarus) were constantly exposed to environmentally relevant concentrations of the synthetic estrogen EE 2 . Mortality, deformities, reproductive parameters, plasma vitellogenin and histopathology were assessed. The results showed that, in the F 0 generation, all endpoints were significantly affected at concentrations higher than 0.2 ng/l EE 2 . No F 1 phenotypic males developed to maturity at 0.2 ng/l and, when adult females of this exposure group were crossed with unexposed males, no F 2 fertile eggs were produced. Kidney histopathology and ultrastructure suggest anomalies possibly associated with increased vitellogenin accumulation. We concluded that the reproduction of the F 1 minnows was completely inhibited at the lowest concentration tested, 0.2 ng/l EE 2 , a concentration frequently detected in surface waters. Growth effects may be related to increased energy requirements including the energy used in VTG synthesis. Reproductive effects are presumably associated with male feminization and the occurrence of testis-ova in males; however, ovarian degeneration observed in females may also have contributed to reproductive failure

  2. An evaluation of the inhibition of human butyrylcholinesterase and acetylcholinesterase by the organophosphate chlorpyrifos oxon

    International Nuclear Information System (INIS)

    Shenouda, Josephine; Green, Paula; Sultatos, Lester

    2009-01-01

    Acetylcholinesterase (EC 3.1.1.7) and butyrylcholinesterase (EC 3.1.1.8) are enzymes that belong to the superfamily of α/β-hydrolase fold proteins. While they share many characteristics, they also possess many important differences. For example, whereas they have about 54% amino acid sequence identity, the active site gorge of acetylcholinesterase is considerably smaller than that of butyrylcholinesterase. Moreover, both have been shown to display simple and complex kinetic mechanisms, depending on the particular substrate examined, the substrate concentration, and incubation conditions. In the current study, incubation of butyrylthiocholine in a concentration range of 0.005-3.0 mM, with 317 pM human butyrylcholinesterase in vitro, resulted in rates of production of thiocholine that were accurately described by simple Michaelis-Menten kinetics, with a K m of 0.10 mM. Similarly, the inhibition of butyrylcholinesterase in vitro by the organophosphate chlorpyrifos oxon was described by simple Michaelis-Menten kinetics, with a k i of 3048 nM -1 h -1 , and a K D of 2.02 nM. In contrast to inhibition of butyrylcholinesterase, inhibition of human acetylcholinesterase by chlorpyrifos oxon in vitro followed concentration-dependent inhibition kinetics, with the k i increasing as the inhibitor concentration decreased. Chlorpyrifos oxon concentrations of 10 and 0.3 nM gave k i s of 1.2 and 19.3 nM -1 h -1 , respectively. Although the mechanism of concentration-dependent inhibition kinetics is not known, the much smaller, more restrictive active site gorge of acetylcholinesterase almost certainly plays a role. Similarly, the much larger active site gorge of butyrylcholinesterase likely contributes to its much greater reactivity towards chlorpyrifos oxon, compared to acetylcholinesterase.

  3. Bringing metabolic networks to life: convenience rate law and thermodynamic constraints

    Directory of Open Access Journals (Sweden)

    Klipp Edda

    2006-12-01

    Full Text Available Abstract Background Translating a known metabolic network into a dynamic model requires rate laws for all chemical reactions. The mathematical expressions depend on the underlying enzymatic mechanism; they can become quite involved and may contain a large number of parameters. Rate laws and enzyme parameters are still unknown for most enzymes. Results We introduce a simple and general rate law called "convenience kinetics". It can be derived from a simple random-order enzyme mechanism. Thermodynamic laws can impose dependencies on the kinetic parameters. Hence, to facilitate model fitting and parameter optimisation for large networks, we introduce thermodynamically independent system parameters: their values can be varied independently, without violating thermodynamical constraints. We achieve this by expressing the equilibrium constants either by Gibbs free energies of formation or by a set of independent equilibrium constants. The remaining system parameters are mean turnover rates, generalised Michaelis-Menten constants, and constants for inhibition and activation. All parameters correspond to molecular energies, for instance, binding energies between reactants and enzyme. Conclusion Convenience kinetics can be used to translate a biochemical network – manually or automatically - into a dynamical model with plausible biological properties. It implements enzyme saturation and regulation by activators and inhibitors, covers all possible reaction stoichiometries, and can be specified by a small number of parameters. Its mathematical form makes it especially suitable for parameter estimation and optimisation. Parameter estimates can be easily computed from a least-squares fit to Michaelis-Menten values, turnover rates, equilibrium constants, and other quantities that are routinely measured in enzyme assays and stored in kinetic databases.

  4. Heterotrophic and mixotrophic growth of Micractinium pusillum Fresenius in the presence of acetate and glucose: effect of light and acetate gradient concentration.

    Science.gov (United States)

    Bouarab, L; Dauta, A; Loudiki, M

    2004-06-01

    The main objective of this study was to determine the importance of secondary mechanism of organic carbon utilization (mixotrophic and heterotrophic modes) in addition to CO2 fixation (photoautotrophic mode) in the green alga, Micractinium pusillum Fresenius (chlorophyta), isolated from a waste stabilization pond. The growth was studied in the presence of acetate and glucose. The incorporation rate of 14C- acetate was measured in the light and in the dark at different concentrations. Finally, in order to underline the role of photosynthesis and respiration processes in the acetate assimilation, the effect of two specific metabolic inhibitors, a specific inhibitor of photosystem II (DCMU) and an uncoupler respiratory (DNP), has been studied. The obtained results showed that M. pusillum grows in the presence of organic substrates, i.e., glucose and acetate, in the light (mixotrophic growth) as well as in the dark (Heterotrophic growth). The growth was much more important in the light than in the dark and more in the presence of glucose than of acetate. In the light, the presence of acetate led to a variation of growth parameters mumax, iotaopt, and beta. The effect of acetate gradient on the growth of the microalga was severe as soon as its concentration in the medium was higher. The acetate uptake followed a Michaelis-Menten kinetic in the light as well as in the dark. The capacity of assimilation was slightly higher in the dark. The utilization of DNP and DCMU indicates that acetate incorporation is an active process depending on both anabolic (photosynthesis) and catabolic (respiration) metabolisms, corroborating the model of the Michaelis-Menten kinetic.

  5. Concentration-dependent interactions of the organophosphates chlorpyrifos oxon and methyl paraoxon with human recombinant acetylcholinesterase

    International Nuclear Information System (INIS)

    Kaushik, R.; Rosenfeld, Clint A.; Sultatos, L.G.

    2007-01-01

    For many decades it has been thought that oxygen analogs (oxons) of organophosphorus insecticides phosphorylate the catalytic site of acetylcholinesterase by a mechanism that follows simple Michaelis-Menten kinetics. More recently, the interactions of at least some oxons have been shown to be far more complex and likely involve binding of oxons to a second site on acetylcholinesterase that modulates the inhibitory capacity of other oxon molecules at the catalytic site. The current study has investigated the interactions of chlorpyrifos oxon and methyl paraoxon with human recombinant acetylcholinesterase. Both chlorpyrifos oxon and methyl paraoxon were found to have k i 's that change as a function of oxon concentration. Furthermore, 10 nM chlorpyrifos oxon resulted in a transient increase in acetylthiocholine hydrolysis, followed by inhibition. Moreover, in the presence of 100 nM chlorpyrifos oxon, acetylthiocholine was found to influence both the K d (binding affinity) and k 2 (phosphorylation constant) of this oxon. Collectively, these results demonstrate that the interactions of chlorpyrifos oxon and methyl paraoxon with acetylcholinesterase cannot be described by simple Michaelis-Menten kinetics but instead support the hypothesis that these oxons bind to a secondary site on acetylcholinesterase, leading to activation/inhibition of the catalytic site, depending on the nature of the substrate and inhibitor. Additionally, these data raise questions regarding the adequacy of estimating risk of low levels of insecticide exposure from direct extrapolation of insecticide dose-response curves since the capacity of individual oxon molecules at low oxon levels could be greater than individual oxon molecules in vivo associated with the dose-response curve

  6. The steady-state kinetics of the NADH-dependent nitrite reductase from Escherichia coli K 12. Nitrite and hydroxylamine reduction.

    Science.gov (United States)

    Jackson, R H; Cole, J A; Cornish-Bowden, A

    1981-01-01

    The reduction of both NO2- and hydroxylamine by the NADH-dependent nitrite reductase of Escherichia coli K 12 (EC 1.6.6.4) appears to follow Michaelis-Menten kinetics over a wide range of NADH concentrations. Substrate inhibition can, however, be detected at low concentrations of the product NAD+. In addition, NAD+ displays mixed product inhibition with respect to NADH and mixed or uncompetitive inhibition with respect to hydroxylamine. These inhibition characteristics are consistent with a mechanism in which hydroxylamine binds during catalysis to a different enzyme form from that generated when NAD+ is released. The apparent maximum velocity with NADH as varied substrate increases as the NAD+ concentration increases from 0.05 to 0.7 mM with 1 mM-NO2- or 100 mM-hydroxylamine as oxidized substrate. This increase is more marked for hydroxylamine reduction than for NO2- reduction. Models incorporating only one binding site for NAD can account for the variation in the Michaelis-Menten parameters for both NADH and hydroxylamine with [NAD+] for hydroxylamine reduction. According to these models, activation of the reaction occurs by reversal of an over-reduction of the enzyme by NADH. If the observed activation of the enzyme by NAD+ derives both from activation of the generation of the enzyme-hydroxylamine complex from the enzyme-NO2- complex during NO2- reduction and from activation of the reduction of the enzyme-hydroxylamine complex to form NH4+, then the variation of Vapp. for NO2- or hydroxylamine with [NAD+] is consistent with the occurrence of the same enzyme-hydroxylamine complex as an intermediate in both reactions. PMID:6279095

  7. An Assessment of Factors Affecting Reactive Transport of Biodegradable BTEX in an Unconfined Aquifer System, Tehran Oil Refinery, Iran

    Directory of Open Access Journals (Sweden)

    A. Agah

    2012-12-01

    Full Text Available Risk-based assessment methods are commonly used at the contaminated sites by hydrocarbon pollutants. This paper presents the results of a two-dimensional finite volume model of reactive transport of biodegradable BTEX which have been developed for the saturated zone of an unconfined aquifer in the Pump station area of Tehran oil refinery, Iran. The model governing equations were numerically solved by modification of a general commercial software called PHOENICS. To reduce costs in general, many input parameters of a model are often approximated based on the used values in the contaminated sites with same conditions. It was not fully recognised the effect of errors in these inputs on modelling outputs. Thus, a sensitivity analysis was carried out to determine the influence of parameters variability on the results of model. For this analysis, the sensitivity of the model to changes in the dispersivity, distribution coefficient, parameters of Monod, Michaelis-Menten, first- and zero- order kinetics modes on the BTEX contaminant plume were examined by performing several simulations. It was found that the model is sensitive to changes in dispersivity and parameters of Michaelis-Menten, first- and zero- order kinetics model. On the other hand, the predictions for plumes assuming Monod kinetics are similar, even if different values for parameterization are chosen. The reason for this insensibility is that degradation is not limited by microbial kinetics in the simulation, but by dispersive mixing. Quantifying the effect of changes in model input parameters on the modelling results is essential when it is desired to recognise which model parameters are more vital on the fate and transport of reactive pollutants. Furthermore, this process can provide an insight into understanding pollutant transportation mechanisms.

  8. Quantification of in vivo metabolic kinetics of hyperpolarized pyruvate in rat kidneys using dynamic 13C MRSI.

    Science.gov (United States)

    Xu, Tao; Mayer, Dirk; Gu, Meng; Yen, Yi-Fen; Josan, Sonal; Tropp, James; Pfefferbaum, Adolf; Hurd, Ralph; Spielman, Daniel

    2011-10-01

    With signal-to-noise ratio enhancements on the order of 10,000-fold, hyperpolarized MRSI of metabolically active substrates allows the study of both the injected substrate and downstream metabolic products in vivo. Although hyperpolarized [1-(13)C]pyruvate, in particular, has been used to demonstrate metabolic activities in various animal models, robust quantification and metabolic modeling remain important areas of investigation. Enzyme saturation effects are routinely seen with commonly used doses of hyperpolarized [1-(13)C]pyruvate; however, most metrics proposed to date, including metabolite ratios, time-to-peak of metabolic products and single exchange rate constants, fail to capture these saturation effects. In addition, the widely used small-flip-angle excitation approach does not correctly model the inflow of fresh downstream metabolites generated proximal to the target slice, which is often a significant factor in vivo. In this work, we developed an efficient quantification framework employing a spiral-based dynamic spectroscopic imaging approach. The approach overcomes the aforementioned limitations and demonstrates that the in vivo (13)C labeling of lactate and alanine after a bolus injection of [1-(13)C]pyruvate is well approximated by saturatable kinetics, which can be mathematically modeled using a Michaelis-Menten-like formulation, with the resulting estimated apparent maximal reaction velocity V(max) and apparent Michaelis constant K(M) being unbiased with respect to critical experimental parameters, including the substrate dose, bolus shape and duration. Although the proposed saturatable model has a similar mathematical formulation to the original Michaelis-Menten kinetics, it is conceptually different. In this study, we focus on the (13)C labeling of lactate and alanine and do not differentiate the labeling mechanism (net flux or isotopic exchange) or the respective contribution of various factors (organ perfusion rate, substrate transport

  9. What happened to anti-malarial markets after the Affordable Medicines Facility-malaria pilot? Trends in ACT availability, price and market share from five African countries under continuation of the private sector co-payment mechanism.

    Science.gov (United States)

    Tougher, Sarah; Hanson, Kara; Goodman, Catherine

    2017-04-25

    The private sector supplies anti-malarial treatment for large proportions of patients in sub-Saharan Africa. Following the large-scale piloting of the Affordable Medicines Facility-malaria (AMFm) from 2010 to 2011, a private sector co-payment mechanism (CPM) provided continuation of private sector subsidies for quality-assured artemisinin combination therapies (QAACT). This article analyses for the first time the extent to which improvements in private sector QAACT supply and distribution observed during the AMFm were maintained or intensified during continuation of the CPM through 2015 in Kenya, Madagascar, Nigeria, Tanzania and Uganda using repeat cross-sectional outlet survey data. QAACT market share in all five countries increased during the AMFm period (p private sector QAACT availability were maintained or improved. In 2014/15, private sector QAACT availability was greater than 70% in Nigeria (84.3%), Kenya (70.5%), Tanzania (83.0%) and Uganda (77.1%), but only 11.2% in Madagascar. QAACT market share was maintained or improved post-AMFm in Nigeria, Tanzania and Uganda, but statistically significant declines were observed in Kenya and Madagascar. In 2014/5, QAACT market share was highest in Kenya and Uganda (48.2 and 47.5%, respectively) followed by Tanzania (39.2%), Nigeria (35.0%), and Madagascar (7.0%). Four of the five countries experienced significant decreases in median QAACT price during the AMFm period. Private sector QAACT prices were maintained or further reduced in Tanzania, Nigeria and Uganda, but prices increased significantly in Kenya and Madagascar. SP prices were consistently lower than those of QAACT in the AMFm period, with the exception of Kenya and Tanzania in 2011, where they were equal. In 2014/5 QAACT remained two to three times more expensive than the most popular non-artemisinin therapy in all countries except Tanzania. Results suggest that a private sector co-payment mechanism for QAACT implemented at national scale for 5 years was

  10. Early Right Ventricular Assist Device Use in Patients Undergoing Continuous-Flow Left Ventricular Assist Device Implantation: Incidence and Risk Factors From the Interagency Registry for Mechanically Assisted Circulatory Support.

    Science.gov (United States)

    Kiernan, Michael S; Grandin, E Wilson; Brinkley, Marshall; Kapur, Navin K; Pham, Duc Thinh; Ruthazer, Robin; Rame, J Eduardo; Atluri, Pavan; Birati, Edo Y; Oliveira, Guilherme H; Pagani, Francis D; Kirklin, James K; Naftel, David; Kormos, Robert L; Teuteberg, Jeffrey J; DeNofrio, David

    2017-10-01

    To investigate preimplant risk factors associated with early right ventricular assist device (RVAD) use in patients undergoing continuous-flow left ventricular assist device (LVAD) surgery. Patients in the Interagency Registry for Mechanically Assisted Circulatory Support who underwent primary continuous-flow-LVAD surgery were examined for concurrent or subsequent RVAD implantation within 14 days of LVAD. Risk factors for RVAD implantation and the combined end point of RVAD or death within 14 days of LVAD were assessed with stepwise logistic regression. We compared survival between patients with and without RVAD using Kaplan-Meier method and Cox proportional hazards modeling. Of 9976 patients undergoing continuous-flow-LVAD implantation, 386 patients (3.9%) required an RVAD within 14 days of LVAD surgery. Preimplant characteristics associated with RVAD use included interagency registry for mechanically assisted circulatory support patient profiles 1 and 2, the need for preoperative extracorporeal membrane oxygenation or renal replacement therapy, severe preimplant tricuspid regurgitation, history of cardiac surgery, and concomitant procedures other than tricuspid valve repair at the time of LVAD. Hemodynamic determinants included elevated right atrial pressure, reduced pulmonary artery pulse pressure, and reduced stroke volume. The final model demonstrated good performance for both RVAD implant (area under the curve, 0.78) and the combined end point of RVAD or death within 14 days (area under the curve, 0.73). Compared with patients receiving an isolated LVAD, patients requiring RVAD had decreased 1- and 6-month survival: 78.1% versus 95.8% and 63.6% versus 87.9%, respectively ( P The need for RVAD implantation after LVAD is associated with indices of global illness severity, markers of end-organ dysfunction, and profiles of hemodynamic instability. © 2017 American Heart Association, Inc.

  11. application of ascorbic acid 2-phosphate as a new voltammetric

    African Journals Online (AJOL)

    a

    acid 2-phosphate (AAP) as a new voltammetric substrate has been described in this paper. In the alkaline buffer .... ALP labeled goat anti-rabbit ..... Classical Michaelis-Menten kinetic experiments were carried out to measure the maximum.

  12. A stochastic model of enzyme kinetics

    Science.gov (United States)

    Stefanini, Marianne; Newman, Timothy; McKane, Alan

    2003-10-01

    Enzyme kinetics is generally modeled by deterministic rate equations, and in the simplest case leads to the well-known Michaelis-Menten equation. It is plausible that stochastic effects will play an important role at low enzyme concentrations. We have addressed this by constructing a simple stochastic model which can be exactly solved in the steady-state. Throughout a wide range of parameter values Michaelis-Menten dynamics is replaced by a new and simple theoretical result.

  13. Fabrication, interfacial characterization and mechanical properties of continuous Al{sub 2}O{sub 3} ceramic fiber reinforced Ti/Al{sub 3}Ti metal-intermetallic laminated (CCFR-MIL) composite

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yuqiang; Lin, Chunfa; Han, Xiaoxiao; Chang, Yunpeng; Guo, Chunhuan, E-mail: guochunhuan@hrbeu.edu.cn; Jiang, Fengchun, E-mail: fengchunjiang@hrbeu.edu.cn

    2017-03-14

    Continuous Al{sub 2}O{sub 3} ceramic fiber reinforced Ti/Al{sub 3}Ti metal-intermetallic laminated (CCFR-MIL) composite was fabricated using a vacuum hot pressing (VHP) sintering method and followed by hot isostatic pressing (HIP). The microstructure characteristics of the interfaces between Ti and Al{sub 3}Ti, as well as Al{sub 2}O{sub 3} fiber and Al{sub 3}Ti intermetallic were analyzed by scanning electron microscopy (SEM). Elemental distribution in the interfacial reaction zones were quantitatively examined by energy-dispersive spectroscopy (EDS). The phases in the composite were identified by X-ray diffractometer (XRD). The mechanical properties of the CCFR-MIL composite were measured using compression and tensile tests under quasi-static strain rate. The experimental results indicated that the residual Al was found in Al{sub 3}Ti intermetallic layer of CCFR-MIL composite. The interfacial reactions occurred during HIP and the reaction products were determined to be Al{sub 2}Ti, TiSi{sub 2}, TiO{sub 2} and Al{sub 2}SiO{sub 5} phases. Compared to Ti/Al{sub 3}Ti MIL composite without fiber reinforcement, both the strength and failure strain of CCFR-MIL composite under both compressive and tensile stress states increased due to the contribution of the continuous ceramic Al{sub 2}O{sub 3} fiber.

  14. Between strong continuity and almost continuity

    Directory of Open Access Journals (Sweden)

    J.K. Kohli

    2010-04-01

    Full Text Available As embodied in the title of the paper strong and weak variants of continuity that lie strictly between strong continuity of Levine and almost continuity due to Singal and Singal are considered. Basic properties of almost completely continuous functions (≡ R-maps and δ-continuous functions are studied. Direct and inverse transfer of topological properties under almost completely continuous functions and δ-continuous functions are investigated and their place in the hier- archy of variants of continuity that already exist in the literature is out- lined. The class of almost completely continuous functions lies strictly between the class of completely continuous functions studied by Arya and Gupta (Kyungpook Math. J. 14 (1974, 131-143 and δ-continuous functions defined by Noiri (J. Korean Math. Soc. 16, (1980, 161-166. The class of almost completely continuous functions properly contains each of the classes of (1 completely continuous functions, and (2 al- most perfectly continuous (≡ regular set connected functions defined by Dontchev, Ganster and Reilly (Indian J. Math. 41 (1999, 139-146 and further studied by Singh (Quaestiones Mathematicae 33(2(2010, 1–11 which in turn include all δ-perfectly continuous functions initi- ated by Kohli and Singh (Demonstratio Math. 42(1, (2009, 221-231 and so include all perfectly continuous functions introduced by Noiri (Indian J. Pure Appl. Math. 15(3 (1984, 241-250.

  15. Sentirse apoyado: Experiencia de pacientes en Ventilación Mecánica sin efectos de sedación continua To feel leaning: Experience of patient in mechanical ventilation without continuous sedation effects

    Directory of Open Access Journals (Sweden)

    Ángela María Henao Castaño

    2010-09-01

    Full Text Available Objetivo: Describir los mecanismos de afrontamiento utilizados por los pacientes que se encuentran sometidos a ventilación mecánica sin efectos de sedación continúa en una UCI. Metodología: se realizó una investigación con enfoque fenomenológico que contó con la participación de siete hombres y dos mujeres con edades entre 24 y 75 años. La técnica de recolección de la información fue la entrevista a profundidad. Resultados: "Sentirse apoyado y magnificar la espiritualidad", estar críticamente enfermo hace que se vivan situaciones de sufrimiento y soledad, convirtiendo a la familia y a la creencia religiosa como partes del proceso de recuperación. Conclusión: vivir la experiencia de la ventilación mecánica sin efectos de sedación fue para los participantes trascendental debido a que percibieron durante su proceso de enfermedad el apoyo que la familia y la creencia religiosa les brindó para poder recuperarse; la familia son personas que dan palabras de aliento, brindan ayuda emocional y espiritual.Objective: to describe the confrontation mechanisms used by the patients that are subjected to mechanical ventilation without effects of continues sedation in an ICU. Methodology: it was carried out an investigation with phenomelogycal focus that had the participation of seven men and two women between 24 and 75 years old. The technique of gathering of the information was the interview in depth. Results: "to feel leaning and to magnify the spirituality". To be critically sick makes that situations of suffering and solitude been lived, converting the family and religious belief as parts of the recovery process. Conclusion: to live the experience of the mechanical ventilation without sedation effects was for the participants deeply significant because they perceived during their illness the support that the family and the religious belief offer them to be able to recover; the family is people that give words of encouragement, they

  16. Continuous culture apparatus and methodology

    International Nuclear Information System (INIS)

    Conway, H.L.

    1975-01-01

    At present, we are investigating the sorption of potentially toxic trace elements by phytoplankton under controlled laboratory conditions. Continuous culture techniques were used to study the mechanism of the sorption of the trace elements by unialgal diatom populations and the factors influencing this sorption. Continuous culture methodology has been used extensively to study bacterial kinetics. It is an excellent technique for obtaining a known physiological state of phytoplankton populations. An automated method for the synthesis of continuous culture medium for use in these experiments is described

  17. Multicentre randomised controlled trial to investigate the usefulness of continuous pneumatic regulation of tracheal cuff pressure for reducing ventilator-associated pneumonia in mechanically ventilated severe trauma patients: the AGATE study protocol.

    Science.gov (United States)

    Marjanovic, Nicolas; Frasca, Denis; Asehnoune, Karim; Paugam, Catherine; Lasocki, Sigismond; Ichai, Carole; Lefrant, Jean-Yves; Leone, Marc; Dahyot-Fizelier, Claire; Pottecher, Julien; Falcon, Dominique; Veber, Benoit; Constantin, Jean-Michel; Seguin, Sabrina; Guénézan, Jérémy; Mimoz, Olivier

    2017-08-07

    Severe trauma represents the leading cause of mortality worldwide. While 80% of deaths occur within the first 24 hours after trauma, 20% occur later and are mainly due to healthcare-associated infections, including ventilator-associated pneumonia (VAP). Preventing underinflation of the tracheal cuff is recommended to reduce microaspiration, which plays a major role in the pathogenesis of VAP. Automatic devices facilitate the regulation of tracheal cuff pressure, and their implementation has the potential to reduce VAP. The objective of this work is to determine whether continuous regulation of tracheal cuff pressure using a pneumatic device reduces the incidence of VAP compared with intermittent control in severe trauma patients. This multicentre randomised controlled and open-label trial will include patients suffering from severe trauma who are admitted within the first 24 hours, who require invasive mechanical ventilation to longer than 48 hours. Their tracheal cuff pressure will be monitored either once every 8 hours (control group) or continuously using a pneumatic device (intervention group). The primary end point is the proportion of patients that develop VAP in the intensive care unit (ICU) at day 28. The secondary end points include the proportion of patients that develop VAP in the ICU, early (≤7 days) or late (>7 days) VAP, time until the first VAP diagnosis, the number of ventilator-free days and antibiotic-free days, the length of stay in the ICU, the proportion of patients with ventilator-associated events and that die during their ICU stay. This protocol has been approved by the ethics committee of Poitiers University Hospital, and will be carried out according to the principles of the Declaration of Helsinki and the Good Clinical Practice guidelines. The results of this study will be disseminated through presentation at scientific conferences and publication in peer-reviewed journals. Clinical Trials NCT02534974. © Article author(s) (or

  18. 15 CFR 923.57 - Continuing consultation.

    Science.gov (United States)

    2010-01-01

    ... § 923.57 Continuing consultation. (a) As required by subsection 306(d)(3)(B) of the Act, a State must establish an effective mechanism for continuing consultation and coordination between the management agency... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Continuing consultation. 923.57...

  19. 21 CFR 868.5895 - Continuous ventilator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Continuous ventilator. 868.5895 Section 868.5895...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5895 Continuous ventilator. (a) Identification. A continuous ventilator (respirator) is a device intended to mechanically control or assist...

  20. Different Mechanisms of Soil Microbial Response to Global Change Result in Different Outcomes in the MIMICS-CN Model

    Science.gov (United States)

    Kyker-Snowman, E.; Wieder, W. R.; Grandy, S.

    2017-12-01

    Microbial-explicit models of soil carbon (C) and nitrogen (N) cycling have improved upon simulations of C and N stocks and flows at site-to-global scales relative to traditional first-order linear models. However, the response of microbial-explicit soil models to global change factors depends upon which parameters and processes in a model are altered by those factors. We used the MIcrobial-MIneral Carbon Stabilization Model with coupled N cycling (MIMICS-CN) to compare modeled responses to changes in temperature and plant inputs at two previously-modeled sites (Harvard Forest and Kellogg Biological Station). We spun the model up to equilibrium, applied each perturbation, and evaluated 15 years of post-perturbation C and N pools and fluxes. To model the effect of increasing temperatures, we independently examined the impact of decreasing microbial C use efficiency (CUE), increasing the rate of microbial turnover, and increasing Michaelis-Menten kinetic rates of litter decomposition, plus several combinations of the three. For plant inputs, we ran simulations with stepwise increases in metabolic litter, structural litter, whole litter (structural and metabolic), or labile soil C. The cumulative change in soil C or N varied in both sign and magnitude across simulations. For example, increasing kinetic rates of litter decomposition resulted in net releases of both C and N from soil pools, while decreasing CUE produced short-term increases in respiration but long-term accumulation of C in litter pools and shifts in soil C:N as microbial demand for C increased and biomass declined. Given that soil N cycling constrains the response of plant productivity to global change and that soils generate a large amount of uncertainty in current earth system models, microbial-explicit models are a critical opportunity to advance the modeled representation of soils. However, microbial-explicit models must be improved by experiments to isolate the physiological and stoichiometric

  1. Completely continuous and weakly completely continuous abstract ...

    Indian Academy of Sciences (India)

    An algebra A is called right completely continuous (right weakly completely continuous) ... Moreover, some applications of these results in group algebras are .... A linear subspace S(G) of L1(G) is said to be a Segal algebra, if it satisfies the.

  2. Providing Continuous Assurance

    NARCIS (Netherlands)

    Kocken, Jonne; Hulstijn, Joris

    2017-01-01

    It has been claimed that continuous assurance can be attained by combining continuous monitoring by management, with continuous auditing of data streams and the effectiveness of internal controls by an external auditor. However, we find that in existing literature the final step to continuous

  3. Quantum mechanics

    CERN Document Server

    Rae, Alastair I M

    2016-01-01

    A Thorough Update of One of the Most Highly Regarded Textbooks on Quantum Mechanics Continuing to offer an exceptionally clear, up-to-date treatment of the subject, Quantum Mechanics, Sixth Edition explains the concepts of quantum mechanics for undergraduate students in physics and related disciplines and provides the foundation necessary for other specialized courses. This sixth edition builds on its highly praised predecessors to make the text even more accessible to a wider audience. It is now divided into five parts that separately cover broad topics suitable for any general course on quantum mechanics. New to the Sixth Edition * Three chapters that review prerequisite physics and mathematics, laying out the notation, formalism, and physical basis necessary for the rest of the book * Short descriptions of numerous applications relevant to the physics discussed, giving students a brief look at what quantum mechanics has made possible industrially and scientifically * Additional end-of-chapter problems with...

  4. Business Continuity Management Plan

    Science.gov (United States)

    2014-12-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA MBA PROFESSIONAL REPORT BUSINESS CONTINUITY MANAGEMENT PLAN December 2014......maximum 200 words) Navy Supply Systems Command (NAVSUP) lacks a business process framework for the development of Business Continuity Management

  5. Smarandache Continued Fractions

    OpenAIRE

    Ibstedt, H.

    2001-01-01

    The theory of general continued fractions is developed to the extent required in order to calculate Smarandache continued fractions to a given number of decimal places. Proof is given for the fact that Smarandache general continued fractions built with positive integer Smarandache sequences baving only a finite number of terms equal to 1 is convergent. A few numerical results are given.

  6. Plants under continuous light

    NARCIS (Netherlands)

    Velez Ramirez, A.I.; Ieperen, van W.; Vreugdenhill, D.; Millenaar, F.F.

    2011-01-01

    Continuous light is an essential tool for understanding the plant circadian clock. Additionally, continuous light might increase greenhouse food production. However, using continuous light in research and practice has its challenges. For instance, most of the circadian clock-oriented experiments

  7. Insight into the mechanism revealing the peroxidase mimetic catalytic activity of quaternary CuZnFeS nanocrystals: colorimetric biosensing of hydrogen peroxide and glucose

    Science.gov (United States)

    Dalui, Amit; Pradhan, Bapi; Thupakula, Umamahesh; Khan, Ali Hossain; Kumar, Gundam Sandeep; Ghosh, Tanmay; Satpati, Biswarup; Acharya, Somobrata

    2015-05-01

    Artificial enzyme mimetics have attracted immense interest recently because natural enzymes undergo easy denaturation under environmental conditions restricting practical usefulness. We report for the first time chalcopyrite CuZnFeS (CZIS) alloyed nanocrystals (NCs) as novel biomimetic catalysts with efficient intrinsic peroxidase-like activity. Novel peroxidase activities of CZIS NCs have been evaluated by catalytic oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). CZIS NCs demonstrate the synergistic effect of elemental composition and photoactivity towards peroxidase-like activity. The quaternary CZIS NCs show enhanced intrinsic peroxidase-like activity compared to the binary NCs with the same constituent elements. Intrinsic peroxidase-like activity has been correlated with the energy band position of CZIS NCs extracted using scanning tunneling spectroscopy and ultraviolet photoelectron spectroscopy. Kinetic analyses indicate Michaelis-Menten enzyme kinetic model catalytic behavior describing the rate of the enzymatic reaction by correlating the reaction rate with substrate concentration. Typical color reactions arising from the catalytic oxidation of TMB over CZIS NCs with H2O2 have been utilized to establish a simple and sensitive colorimetric assay for detection of H2O2 and glucose. CZIS NCs are recyclable catalysts showing high efficiency in multiple uses. Our study may open up the possibility of designing new photoactive multi-component alloyed NCs as enzyme mimetics in biotechnology applications.Artificial enzyme mimetics have attracted immense interest recently because natural enzymes undergo easy denaturation under environmental conditions restricting practical usefulness. We report for the first time chalcopyrite CuZnFeS (CZIS) alloyed nanocrystals (NCs) as novel biomimetic catalysts with efficient intrinsic peroxidase-like activity. Novel peroxidase activities of CZIS NCs have been

  8. On the continuity of the entropy

    International Nuclear Information System (INIS)

    Lassner, G.; Lassner, G.A.

    1977-01-01

    It is shown for a quantum-mechanical system with finite degree of freedom taking into account also unbounded observables one gets physical topologies on the state-observable system with respect to which the entropy becomes a continuous function

  9. Cutting Out Continuations

    DEFF Research Database (Denmark)

    Bahr, Patrick; Hutton, Graham

    2016-01-01

    In the field of program transformation, one often transforms programs into continuation-passing style to make their flow of control explicit, and then immediately removes the resulting continuations using defunctionalisation to make the programs first-order. In this article, we show how these two...... transformations can be fused together into a single transformation step that cuts out the need to first introduce and then eliminate continuations. Our approach is calculational, uses standard equational reasoning techniques, and is widely applicable....

  10. Transient competitive complexation in biological kinetic isotope fractionation explains nonsteady isotopic effects: Theory and application to denitrification in soils

    Science.gov (United States)

    Maggi, Federico; Riley, William J.

    2009-12-01

    The theoretical formulation of biological kinetic isotope fractionation often assumes first-order or Michaelis-Menten kinetics, the latter solved under the quasi-steady state assumption. Both formulations lead to a constant isotope fractionation factor, therefore they may return incorrect estimations of isotopic effects and misleading interpretations of isotopic signatures when fractionation is not a steady process. We have analyzed the isotopic signature of denitrification in biogeochemical soil systems by Menyailo and Hungate (2006) in which high and variable 15N-N2O enrichment during N2O production and inverse isotope fractionation during N2O consumption could not be explained with first-order kinetics and the Rayleigh equation, or with Michaelis-Menten kinetics. When Michaelis-Menten kinetics were coupled to Monod kinetics to describe biomass and enzyme dynamics, and the quasi-steady state assumption was relaxed, transient Michaelis-Menten-Monod kinetics accurately reproduced the observed concentrations, and variable and inverse isotope fractionations. These results imply a substantial revision in modeling isotopic effects, suggesting that steady state kinetics such as first-order, Rayleigh, and classic Michaelis-Menten kinetics should be superseded by transient kinetics in conjunction with biomass and enzyme dynamics.

  11. Archives: Continuing Medical Education

    African Journals Online (AJOL)

    Items 51 - 88 of 88 ... Archives: Continuing Medical Education. Journal Home > Archives: Continuing Medical Education. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 51 - 88 of 88 ...

  12. Generalized analytic continuation

    CERN Document Server

    Ross, William T

    2002-01-01

    The theory of generalized analytic continuation studies continuations of meromorphic functions in situations where traditional theory says there is a natural boundary. This broader theory touches on a remarkable array of topics in classical analysis, as described in the book. This book addresses the following questions: (1) When can we say, in some reasonable way, that component functions of a meromorphic function on a disconnected domain, are "continuations" of each other? (2) What role do such "continuations" play in certain aspects of approximation theory and operator theory? The authors use the strong analogy with the summability of divergent series to motivate the subject. In this vein, for instance, theorems can be described as being "Abelian" or "Tauberian". The introductory overview carefully explains the history and context of the theory. The authors begin with a review of the works of Poincaré, Borel, Wolff, Walsh, and Gončar, on continuation properties of "Borel series" and other meromorphic func...

  13. Influence of continuous electron irradiation and different modes of mechanic-thermal treatment on structure-phase composition of alloys 36NKhTYu and 40KhNYu

    International Nuclear Information System (INIS)

    Alontseva, D.L.; Suslov, S.E.; Kupchishin, A.I.; Plotnikov, S.V.; Petrov, V.A.

    2002-01-01

    Principal regularities of structure formation in strongly deformed alloys 36NKhTYu and 40KhNYu under aging in certain temperature range and after electron irradiation are revealed. Morphological features of precipitating phases with purpose of development of methods for getting of optimal structural states providing essential properties rate were determined. Data of electron microscopic examinations of structure-phase composition are compared with data on mechanical properties

  14. Continuously rotating cat scanning apparatus and method

    International Nuclear Information System (INIS)

    Bax, R.F.

    1980-01-01

    A tomographic scanner with a continuously rotating source of radiation is energized by converting inertial mechanical energy to electrical energy. The mechanical-to-electrical conversion apparatus is mounted with the x-ray source to be energized on a rotating flywheel. The inertial mechanical energy stored in the rotating conversion apparatus, flywheel and x-ray source is utilized for generating electrical energy used, in turn, to energize the x-ray source

  15. Using a Mechanistic Reactive Transport Model to Represent Soil Organic Matter Dynamics and Climate Sensitivity

    Science.gov (United States)

    Guerry, N.; Riley, W. J.; Maggi, F.; Torn, M. S.; Kleber, M.

    2011-12-01

    The nature of long term Soil Organic Matter (SOM) dynamics is uncertain and the mechanisms involved are crudely represented in site, regional, and global models. Recent work challenging the paradigm that SOM is stabilized because of its sequential transformations to more intrinsically recalcitrant compounds motivated us to develop a mechanistic modeling framework that can be used to test hypotheses of SOM dynamics. We developed our C cycling model in TOUGHREACT, an established 3-dimensional reactive transport solver that accounts for multiple phases (aqueous, gaseous, sorbed), multiple species, advection and diffusion, and multiple microbial populations. Energy and mass exchange through the soil boundaries are accounted for via ground heat flux, rainfall, C sources (e.g., exudation, woody, leaf, root litter) and C losses (e.g., CO2 emissions and DOC deep percolation). SOM is categorized according to the various types of compounds commonly found in the above mentioned C sources and microbial byproducts, including poly- and monosaccharides, lignin, amino compounds, organic acids, nucleic acids, lipids, and phenols. Each of these compounds is accounted for by one or more representative species in the model. A reaction network was developed to describe the microbially-mediated processes and chemical interactions of these species, including depolymerization, microbial assimilation, respiration and deposition of byproducts, and incorporation of dead biomass into SOM stocks. Enzymatic reactions are characterized by Michaelis-Menten kinetics, with maximum reaction rates determined by the species' O/C ratio. Microbial activity is further regulated by soil moisture content, O2 availability, pH, and temperature. For the initial set of simulations, literature values were used to constrain microbial Monod parameters, Michaelis-Menten parameters, sorption parameters, physical protection, partitioning of microbial byproducts, and partitioning of litter inputs, although there is

  16. Trieste will continue

    International Nuclear Information System (INIS)

    1968-01-01

    Trieste will continue to be the home of the International Centre for Theoretical Physics for the foreseeable future. An agreement signed in Vienna during December between the Italian Government and the Agency brought this assurance. (author)

  17. Nocturnal continuous glucose monitoring

    DEFF Research Database (Denmark)

    Bay, Christiane; Kristensen, Peter Lommer; Pedersen-Bjergaard, Ulrik

    2013-01-01

    Abstract Background: A reliable method to detect biochemical nocturnal hypoglycemia is highly needed, especially in patients with recurrent severe hypoglycemia. We evaluated reliability of nocturnal continuous glucose monitoring (CGM) in patients with type 1 diabetes at high risk of severe...

  18. Continual improvement plan

    Science.gov (United States)

    1994-01-01

    NASA's approach to continual improvement (CI) is a systems-oriented, agency-wide approach that builds on the past accomplishments of NASA Headquarters and its field installations and helps achieve NASA's vision, mission, and values. The NASA of the future will fully use the principles of continual improvement in every aspect of its operations. This NASA CI plan defines a systematic approach and a model for continual improvement throughout NASA, stressing systems integration and optimization. It demonstrates NASA's constancy of purpose for improvement - a consistent vision of NASA as a worldwide leader in top-quality science, technology, and management practices. The CI plan provides the rationale, structures, methods, and steps, and it defines NASA's short term (1-year) objectives for improvement. The CI plan presents the deployment strategies necessary for cascading the goals and objectives throughout the agency. It also provides guidance on implementing continual improvement with participation from top leadership and all levels of employees.

  19. Continuing Medical Education

    African Journals Online (AJOL)

    Continuing Medical Education. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 25, No 9 (2007) >. Log in or Register to get access to full text downloads.

  20. Branching trajectory continual integral

    International Nuclear Information System (INIS)

    Maslov, V.P.; Chebotarev, A.M.

    1980-01-01

    Heuristic definition of the Feynman continual integral over branching trajectories is suggested which makes it possible to obtain in the closed form the solution of the Cauchy problem for the model Hartree equation. A number of properties of the solution is derived from an integral representation. In particular, the quasiclassical asymptotics, exact solution in the gaussian case and perturbation theory series are described. The existence theorem for the simpliest continual integral over branching trajectories is proved [ru

  1. Hydrodynamic chronoamperometry for probing kinetics of anaerobic microbial metabolism--case study of Faecalibacterium prausnitzii.

    Science.gov (United States)

    Prévoteau, Antonin; Geirnaert, Annelies; Arends, Jan B A; Lannebère, Sylvain; Van de Wiele, Tom; Rabaey, Korneel

    2015-07-01

    Monitoring in vitro the metabolic activity of microorganisms aids bioprocesses and enables better understanding of microbial metabolism. Redox mediators can be used for this purpose via different electrochemical techniques that are either complex or only provide non-continuous data. Hydrodynamic chronoamperometry using a rotating disc electrode (RDE) can alleviate these issues but was seldom used and is poorly characterized. The kinetics of Faecalibacterium prausnitzii A2-165, a beneficial gut microbe, were determined using a RDE with riboflavin as redox probe. This butyrate producer anaerobically ferments glucose and reduces riboflavin whose continuous monitoring on a RDE provided highly accurate kinetic measurements of its metabolism, even at low cell densities. The metabolic reaction rate increased linearly over a broad range of cell concentrations (9 × 10(4) to 5 × 10(7) cells.mL(-1)). Apparent Michaelis-Menten kinetics was observed with respect to riboflavin (KM = 6 μM; kcat = 5.3 × 10(5) s(-1), at 37 °C) and glucose (KM = 6 μM; kcat = 2.4 × 10(5) s(-1)). The short temporal resolution allows continuous monitoring of fast cellular events such as kinetics inhibition with butyrate. Furthermore, we detected for the first time riboflavin reduction by another potential probiotic, Butyricicoccus pullicaecorum. The ability of the RDE for fast, accurate, simple and continuous measurements makes it an ad hoc tool for assessing bioprocesses at high resolution.

  2. High-throughput continuous cryopump

    International Nuclear Information System (INIS)

    Foster, C.A.

    1986-01-01

    A cryopump with a unique method of regeneration which allows continuous operation at high throughput has been constructed and tested. Deuterium was pumped continuously at a throughput of 30 Torr.L/s at a speed of 2000 L/s and a compression ratio of 200. Argon was pumped at a throughput of 60 Torr.L/s at a speed of 1275 L/s. To produce continuous operation of the pump, a method of regeneration that does not thermally cycle the pump is employed. A small chamber (the ''snail'') passes over the pumping surface and removes the frost from it either by mechanical action with a scraper or by local heating. The material removed is topologically in a secondary vacuum system with low conductance into the primary vacuum; thus, the exhaust can be pumped at pressures up to an effective compression ratio determined by the ratio of the pumping speed to the leakage conductance of the snail. The pump, which is all-metal-sealed and dry and which regenerates every 60 s, would be an ideal system for pumping tritium. Potential fusion applications are for mpmp limiters, for repeating pneumatic pellet injection lines, and for the centrifuge pellet injector spin tank, all of which will require pumping tritium at high throughput. Industrial applications requiring ultraclean pumping of corrosive gases at high throughput, such as the reactive ion etch semiconductor process, may also be feasible

  3. Continuous Markovian Logics

    DEFF Research Database (Denmark)

    Mardare, Radu Iulian; Cardelli, Luca; Larsen, Kim Guldstrand

    2012-01-01

    Continuous Markovian Logic (CML) is a multimodal logic that expresses quantitative and qualitative properties of continuous-time labelled Markov processes with arbitrary (analytic) state-spaces, henceforth called continuous Markov processes (CMPs). The modalities of CML evaluate the rates...... of the exponentially distributed random variables that characterize the duration of the labeled transitions of a CMP. In this paper we present weak and strong complete axiomatizations for CML and prove a series of metaproperties, including the finite model property and the construction of canonical models. CML...... characterizes stochastic bisimilarity and it supports the definition of a quantified extension of the satisfiability relation that measures the "compatibility" between a model and a property. In this context, the metaproperties allows us to prove two robustness theorems for the logic stating that one can...

  4. Evaluation of rate law approximations in bottom-up kinetic models of metabolism

    DEFF Research Database (Denmark)

    Du, Bin; Zielinski, Daniel C.; Kavvas, Erol S.

    2016-01-01

    mass action rate law that removes the role of the enzyme from the reaction kinetics. We utilized in vivo data for the human red blood cell to compare the effect of rate law choices against the backdrop of physiological flux and concentration differences. We found that the Michaelis-Menten rate law......Background: The mechanistic description of enzyme kinetics in a dynamic model of metabolism requires specifying the numerical values of a large number of kinetic parameters. The parameterization challenge is often addressed through the use of simplifying approximations to form reaction rate laws....... These approximate rate laws were: 1) a Michaelis-Menten rate law with measured enzyme parameters, 2) a Michaelis-Menten rate law with approximated parameters, using the convenience kinetics convention, 3) a thermodynamic rate law resulting from a metabolite saturation assumption, and 4) a pure chemical reaction...

  5. Continuing bonds and place.

    Science.gov (United States)

    Jonsson, Annika; Walter, Tony

    2017-08-01

    Where do people feel closest to those they have lost? This article explores how continuing bonds with a deceased person can be rooted in a particular place or places. Some conceptual resources are sketched, namely continuing bonds, place attachment, ancestral places, home, reminder theory, and loss of place. The authors use these concepts to analyze interview material with seven Swedes and five Britons who often thought warmly of the deceased as residing in a particular place and often performing characteristic actions. The destruction of such a place, by contrast, could create a troubling, haunting absence, complicating the deceased's absent-presence.

  6. Introduction to Continuous Optimization

    DEFF Research Database (Denmark)

    Andreasson, Niclas; Evgrafov, Anton; Patriksson, Michael

    optimal solutions for continuous optimization models. The main part of the mathematical material therefore concerns the analysis and linear algebra that underlie the workings of convexity and duality, and necessary/sufficient local/global optimality conditions for continuous optimization problems. Natural...... algorithms are then developed from these optimality conditions, and their most important convergence characteristics are analyzed. The book answers many more questions of the form “Why?” and “Why not?” than “How?”. We use only elementary mathematics in the development of the book, yet are rigorous throughout...

  7. Continuous Platform Development

    DEFF Research Database (Denmark)

    Nielsen, Ole Fiil

    low risks and investments but also with relatively fuzzy results. When looking for new platform projects, it is important to make sure that the company and market is ready for the introduction of platforms, and to make sure that people from marketing and sales, product development, and downstream......, but continuous product family evolution challenges this strategy. The concept of continuous platform development is based on the fact that platform development should not be a one-time experience but rather an ongoing process of developing new platforms and updating existing ones, so that product family...

  8. Studies on continuous fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, K

    1958-01-01

    Continuous fermentation of molasses with a combined system of agitated vessel and flow pipe is studied. A new apparatus was designed. The rate of the fermentation was faster with this apparatus than with the former apparatus which was composed of two vessels.

  9. Continuous Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1996-01-01

    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...

  10. Continuous Adductor Canal Blocks

    DEFF Research Database (Denmark)

    Monahan, Amanda M; Sztain, Jacklynn F; Khatibi, Bahareh

    2016-01-01

    on cutaneous knee sensation in volunteers. METHODS: Bilateral adductor canal catheters were inserted in 24 volunteers followed by ropivacaine 0.2% administration for 8 hours. One limb of each subject was assigned randomly to a continuous infusion (8 mL/h) or automated hourly boluses (8 m...

  11. Continuous Personal Improvement.

    Science.gov (United States)

    Emiliani, M. L.

    1998-01-01

    Suggests that continuous improvement tools used in the workplace can be applied to self-improvement. Explains the use of such techniques as one-piece flow, kanban, visual controls, and total productive maintenance. Points out misapplications of these tools and describes the use of fishbone diagrams to diagnose problems. (SK)

  12. Continuity and Change.

    Science.gov (United States)

    Istance, David

    1985-01-01

    Examines issues related to continuity in education and educational change. Indicates that although schools must be responsive to changing social and economic conditions (and contribute to them), they must also be protected against fluctuating swings of educational fashion and safeguard their long-term mission, even when buffeted by short-term…

  13. Promoting Continuing Education Programs.

    Science.gov (United States)

    Hendrickson, Gayle A.

    This handbook is intended for use by institutions in marketing their continuing education programs. A section on "Devising Your Strategy" looks at identifying a target audience, determining the marketing approach, and developing a marketing plan and promotional techniques. A discussion of media options looks at the advantages and…

  14. Continuous quality improvement

    NARCIS (Netherlands)

    Rohlin, Madeleine; Schaub, Rob M.H.; Holbrook, Peter; Leibur, Edvitar; Lévy, Gérard; Roubalikova, Lenka; Nilner, Maria; Roger-Leroi, Valerie; Danner, Gunter; Iseri, Haluk; Feldman, Cecile

    2002-01-01

    Versch. in: Eur J Dent Educ; 6 (Suppl. 3): 67–77 Continuous quality improvement (CQI) can be envisaged as a circular process of goal-setting, followed by external and internal evaluations resulting in improvements that can serve as goals for a next cycle. The need for CQI is apparent, because of

  15. Continuous digital health

    NARCIS (Netherlands)

    Van Halteren, Aart; Gay, Vaĺerie

    2015-01-01

    A transformation is underway regarding how we deal with our health, not only because mobile Internet technology has made it possible to have continuous access to personal health information, but also because breaking the trend of ever-growing healthcare costs is increasingly necessary. Connectivity,

  16. Continuous quality improvement

    International Nuclear Information System (INIS)

    Bourne, P.B.

    1985-01-01

    This paper describes the various statistical tools used at the Hanford Engineering Development Laboratory to achieve continuous quality improvement in the development of Breeder Reactor Technology and in reactor operations. The role of the quality assurance professionals in this process, including quantifiable measurements using actual examples, is provided. The commitment to quality improvement through top management involvement is dramatically illustrated

  17. Continuous feedback fluid queues

    NARCIS (Netherlands)

    Scheinhardt, Willem R.W.; van Foreest, N.D.; Mandjes, M.R.H.

    2003-01-01

    We investigate a fluid buffer which is modulated by a stochastic background process, while the momentary behavior of the background process depends on the current buffer level in a continuous way. Loosely speaking the feedback is such that the background process behaves `as a Markov process' with

  18. Continuing Medical Education

    African Journals Online (AJOL)

    A review article willintroduce readers to the educational subject matter, along with one-page summarises (in print) of additional articles that may be accessed in full online. We will continue to offer topical and up-to-date CME material. Readers are encouraged to register with samj.org.za to receive future notifications of new ...

  19. Continuous venovenous haemodialysis

    DEFF Research Database (Denmark)

    Jensen, Dorte Møller; Bistrup, C; Pedersen, R S

    1996-01-01

    A simple three-pump-based system for the performance of continuous venovenous haemodialysis is described. The method employs access to the circulation via a double-lumen catheter, and by means of a standard extracorporeal peristaltic pump the blood is circulated through a haemofiltration filter....... Standard solutions for peritoneal dialysis are administered in a single-pass manner countercurrent to the blood flow. To control the dialysate flow through the filter, two separate pumps designed for intravenous infusion are used. Anticoagulation is achieved by means of continuous heparin infusion....... This three-pump system is effective in controlling the fluid balance and the level of azotemia. Furthermore, this system makes haemodialysis possible in spite of severe haemodynamic instability. The system is easy to use and inexpensive. 3 patients participated in the study....

  20. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Fareed, Ali [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States); Craig, Phillip A. [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States)

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  1. Deconstructing continuous flash suppression

    OpenAIRE

    Yang, Eunice; Blake, Randolph

    2012-01-01

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in co...

  2. Safety Campaign Continues

    CERN Multimedia

    2002-01-01

    If you see this poster, stop and read it! This is the third poster produced by TIS Division as part of its information campaign on health and safety in the workplace. It provides statistics on occupational accidents at CERN. You will see that, as in the rest of Europe, falls, slips and trips continue to be the main cause of accident. So, eyes open and take care! For more information : http://safety.cern.ch/

  3. Efecto del pastoreo sobre la resistencia mecánica del suelo en sistemas de producción bajo siembra directa continua Impact of cattle grazing on soil mechanical resistance in production systems under continuous no-till

    Directory of Open Access Journals (Sweden)

    Hugo R Krüger

    2008-12-01

    Full Text Available Los objetivos del estudio fueron: a caracterizar la variación de la resistencia mecánica a la penetración (RST de la capa de suelo de 0 a 20 cm en dos rotaciones con y sin pastoreo directo y b establecer su relación con el contenido de agua del suelo (W. El estudio se realizó sobre un Hapludol típico del sudoeste de la provincia de Buenos Aires, sobre secuencias basadas en girasol y trigo. Se estudiaron dos tratamientos: a Agrícola, que no incluyó pastoreo y b Mixta que incorporó un cultivo de avena pastoreado por novillos de 350 a 400 kg (25 cabezas/ha previo al girasol. Se determinaron RST y W en diez fechas de muestreo. Luego del pastoreo de avena, la RST de Mixta fue mayor que la de Agrícola en toda la capa, con picos en 2,5-7,5 cm. Ajustada a un W de 190 g kg-1, la RST de Agrícola mostró una tendencia lineal ligeramente creciente en el tiempo; la RST Mixta ajustó a un modelo cuadrático con tendencia a estabilizarse en valores cercanos a 2,5 MPa. Mixta presentó además un segundo nivel de variación relacionado con las fechas de muestreo: la RST luego del pastoreo de avena fue mayor que al final del ciclo avena-girasol-trigo. La disminución se atribuyó a una recuperación de la bioporosidad por efecto de las raíces de los cultivos. Las RST observadas fueron cercanas o mayores a las críticas para la penetración de las raíces en el 20 y 50% de las fechas de muestreo para Agrícola y Mixta, respectivamente.The objectives of this study, were: a to characterize the soil mechanical penetration resistance (RST variation in the 0 to 20 -cm depth of two rotation treatments with and without cattle grazing and b to determine the RST relationship with soil water content (W. The experiment took place on a Typic Haplustoll in SW Buenos Aires province, on sunflower-wheat based rotations. Treatments included: a 100 % cash-crop rotation with no cattle grazing and b Mixed rotation, including an oat forage crop with direct grazing by 350

  4. Robust continuous clustering.

    Science.gov (United States)

    Shah, Sohil Atul; Koltun, Vladlen

    2017-09-12

    Clustering is a fundamental procedure in the analysis of scientific data. It is used ubiquitously across the sciences. Despite decades of research, existing clustering algorithms have limited effectiveness in high dimensions and often require tuning parameters for different domains and datasets. We present a clustering algorithm that achieves high accuracy across multiple domains and scales efficiently to high dimensions and large datasets. The presented algorithm optimizes a smooth continuous objective, which is based on robust statistics and allows heavily mixed clusters to be untangled. The continuous nature of the objective also allows clustering to be integrated as a module in end-to-end feature learning pipelines. We demonstrate this by extending the algorithm to perform joint clustering and dimensionality reduction by efficiently optimizing a continuous global objective. The presented approach is evaluated on large datasets of faces, hand-written digits, objects, newswire articles, sensor readings from the Space Shuttle, and protein expression levels. Our method achieves high accuracy across all datasets, outperforming the best prior algorithm by a factor of 3 in average rank.

  5. Continuous microwave regeneration apparatus for absorption media

    Science.gov (United States)

    Smith, Douglas D.

    1999-01-01

    A method and apparatus for continuously drying and regenerating ceramic beads for use in process gas moisture drying operations such as glove boxes. A microwave energy source is coupled to a process chamber to internally heat the ceramic beads and vaporize moisture contained therein. In a preferred embodiment, the moisture laden ceramic beads are conveyed toward the microwave source by a screw mechanism. The regenerated beads flow down outside of the screw mechanism and are available to absorb additional moisture.

  6. Kinetic analysis of enzyme systems with suicide substrate in the presence of a reversible competitive inhibitor, tested by simulated progress curves.

    Science.gov (United States)

    Moruno-Dávila, M A; Garrido-del Solo, C; García-Moreno, M; Havsteen, B H; Garcia-Sevilla, F; Garcia-Cánovas, F; Varón, R

    2001-02-01

    The use of suicide substrates remains a very important and useful method in enzymology for studying enzyme mechanisms and designing potential drugs. Suicide substrates act as modified substrates for the target enzymes and bind to the active site. Therefore the presence of a competitive reversible inhibitor decreases the rate of substrate-induced inactivation and protects the enzyme from this inactivation. This lowering on the inactivation rate has evident physiological advantages, since it allows the easy acquisition of experimental data and facilitates kinetic data analysis by providing another variable (inhibitor concentration). However despite the importance of the simultaneous action of a suicide substrate and a competitive reversible inhibition, to date no corresponding kinetic analysis has been carried out. Therefore we present a general kinetic analysis of a Michaelis-Menten reaction mechanism with double inhibition caused by both, a suicide substrate and a competitive reversible inhibitor. We assume rapid equilibrium of the reversible reaction steps involved, while the time course equations for the reaction product have been derived with the assumption of a limiting enzyme. The goodness of the analytical solutions has been tested by comparison with the simulated curves obtained by numerical integration. A kinetic data analysis to determine the corresponding kinetic parameters from the time progress curve of the product is suggested. In conclusion, we present a complete kinetic analysis of an enzyme reaction mechanism as described above in an attempt to fill a gap in the theoretical treatment of this type of system.

  7. Collective behaviours: from biochemical kinetics to electronic circuits

    Science.gov (United States)

    Agliari, Elena; Barra, Adriano; Burioni, Raffaella; di Biasio, Aldo; Uguzzoni, Guido

    2013-12-01

    In this work we aim to highlight a close analogy between cooperative behaviors in chemical kinetics and cybernetics; this is realized by using a common language for their description, that is mean-field statistical mechanics. First, we perform a one-to-one mapping between paradigmatic behaviors in chemical kinetics (i.e., non-cooperative, cooperative, ultra-sensitive, anti-cooperative) and in mean-field statistical mechanics (i.e., paramagnetic, high and low temperature ferromagnetic, anti-ferromagnetic). Interestingly, the statistical mechanics approach allows a unified, broad theory for all scenarios and, in particular, Michaelis-Menten, Hill and Adair equations are consistently recovered. This framework is then tested against experimental biological data with an overall excellent agreement. One step forward, we consistently read the whole mapping from a cybernetic perspective, highlighting deep structural analogies between the above-mentioned kinetics and fundamental bricks in electronics (i.e. operational amplifiers, flashes, flip-flops), so to build a clear bridge linking biochemical kinetics and cybernetics.

  8. Design and application of a fluorogenic assay for monitoring inflammatory caspase activity.

    Science.gov (United States)

    Ranganathan, Raj; Lenti, Gena; Tassone, Nicholas M; Scannell, Brian J; Southern, Cathrine A; Karver, Caitlin E

    2018-02-15

    Various fluorogenic assays exist for monitoring the activity of inflammatory caspases. However, there are no continuous assays that provide C-terminal substrate sequence specificity for inflammatory caspases. As a first step towards this, we have developed a continuous in vitro assay that relies on monitoring emission from tryptophan after cleavage of a quenching coumarin chromophore. The coumarin can be attached as an amino acid side chain or capping the C-terminus of the peptide. When the coumarin is a side chain, it allows for C-terminal and N-terminal sequence specificities to be explored. Using this assay, we obtained Michaelis-Menten kinetic data for four proof-of-principle peptides: WEHD-AMC (K M  = 15 ± 2 μM), WEHD-MCA (K M  = 93 ± 19 μM), WEHDG-MCA (K M  = 21 ± 6 μM) and WEHDA-MCA (K M  = 151 ± 37 μM), where AMC is 7-amino-4-methylcoumarin and MCA is β-(7-methoxy-coumarin-4-yl)-Ala. The results indicate the viability of this new assay approach in the design of effective fluorogenic substrates for inflammatory caspases. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Development of a highly efficient indigo dyeing method using indican with an immobilized beta-glucosidase from Aspergillus niger.

    Science.gov (United States)

    Song, Jingyuan; Imanaka, Hiroyuki; Imamura, Koreyoshi; Kajitani, Kouichi; Nakanishi, Kazuhiro

    2010-09-01

    A highly efficient method for dyeing textiles with indigo is described. In this method, the substrate, indican is first hydrolyzed at an acidic pH of 3 using an immobilized beta-glucosidase to produce indoxyl, under which conditions indigo formation is substantially repressed. The textile sample is then dipped in the prepared indoxyl solution and the textile is finally exposed to ammonia vapor for a short time, resulting in rapid indigo dyeing. As an enzyme, we selected a beta-glucosidase from Aspergillus niger, which shows a high hydrolytic activity towards indican and was thermally stable at temperatures up to 50-60 degrees C, in an acidic pH region. The A. niger beta-glucosidase, when immobilized on Chitopearl BCW-3001 by treatment with glutaraldehyde, showed an optimum reaction pH similar to that of the free enzyme with a slightly higher thermal stability. The kinetics for the hydrolysis of indican at pH 3, using the purified free and immobilized enzymes was found to follow Michaelis-Menten type kinetics with weak competitive inhibition by glucose. Using the immobilized enzyme, we successfully carried out repeated-batch and continuous hydrolyses of indican at pH 3 when nitrogen gas was continuously supplied to the substrate solution. Various types of model textiles were dyed using the proposed method although the color yield varied, depending on the type of textile used. Copyright 2010 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  10. Continuous positive airway pressure (CPAP).

    Science.gov (United States)

    Sahni, R; Wung, J T

    1998-01-01

    Progress in neonatal intensive care is closely linked to improvements in the management of respiratory failure in small infants. This applies to the care of the preterm infants with immature lungs, and also to treatment of the preterm or full term infants with specific diseases that are associated with respiratory failure. Respiratory distress of the newborn continues to account for significant morbidity in the intensive care unit. The spectrum of disease ranges from mild distress to severe respiratory failure requiring varying degrees of support. The current modalities of ventilatory assistance range from the more benign continuous positive airway pressure (CPAP) to conventional mechanical ventilation, and on to high frequency ventilation. It is a reasonable supposition that the type of ventilatory assistance provided to these infants should be graded according to the severity of the disease. However, the principal objective in selecting the mode of respiratory support should be to use a modality which results in minimal volo- or barotrauma to the infant. The following detailed description on CPAP explains its physiological effects, delivery system, indications for use, application, maintenance, and associated complications. The equipment described is simple to use, has a greater cost benefit, and has a more universal application, which is of help to smaller units including those in the developing parts of the world. We have also included our institutional clinical experience of CPAP usage in very low birth weight infants from the periods before and after commercial availability of surfactant in the United States.

  11. Continuous multivariate exponential extension

    International Nuclear Information System (INIS)

    Block, H.W.

    1975-01-01

    The Freund-Weinman multivariate exponential extension is generalized to the case of nonidentically distributed marginal distributions. A fatal shock model is given for the resulting distribution. Results in the bivariate case and the concept of constant multivariate hazard rate lead to a continuous distribution related to the multivariate exponential distribution (MVE) of Marshall and Olkin. This distribution is shown to be a special case of the extended Freund-Weinman distribution. A generalization of the bivariate model of Proschan and Sullo leads to a distribution which contains both the extended Freund-Weinman distribution and the MVE

  12. Continuity and consensus

    DEFF Research Database (Denmark)

    Abrahamson, Peter

    2010-01-01

    maternal leave. These changes can be explained as adjustments to post-industrial conditions within a political culture relying on class compromises and a broad consensus informed by expert advice coming from civil servants and ad hoc policy commissions. The paper concludes that changes in Danish family...... policy reflect changing conditions for employment and the minding of children and that there has been a high degree of continuity and consensus about the change, as indicated by the strong increase in female labour market involvement....

  13. Continuous Integration in CFMGR

    CERN Document Server

    Frohlingsdorf, David

    2017-01-01

    Cfmgr is a managing tool for network devices. At the moment there is no way to automatically check the working behaviour of the tool, meaning that a lot of effort is spend into manually testing the tool after an update. During my stay at CERN I developed a black-box testing framework for Cfmgr according to Continuous Integration practices and successfully deployed the framework using Jenkins and Docker. This report discusses in detail how the framework works and how it can be configured, and equally gives a broad problem description and outlines future work directions.

  14. Continuous-infusion adriamycin

    International Nuclear Information System (INIS)

    Benjamin, R.S.; Chawla, S.P.; Ewer, M.S.; Hortobagyi, G.N.

    1986-01-01

    This chapter discusses the diminished cardiotoxicity as well as diminished nausea and vomiting with continuous infusions of adriamycin to patients undergoing radiation therapy, particularly with infusions of 48 hours or longer, and best with 96-hour infusions, the longest duration that has been studied systematically. In breast cancer, data show that more adriamycin is better, but only for a selected subgroup of patients: those with complete remission. The diminished cardiotoxicity makes the use of adriamycin more attractive in the adjuvant situation, where increased safety will decrease the chances of long-term complications and make retreatment easy for cured patients who develop second malignancies

  15. Continuous Shearlet Tight Frames

    KAUST Repository

    Grohs, Philipp

    2010-10-22

    Based on the shearlet transform we present a general construction of continuous tight frames for L2(ℝ2) from any sufficiently smooth function with anisotropic moments. This includes for example compactly supported systems, piecewise polynomial systems, or both. From our earlier results in Grohs (Technical report, KAUST, 2009) it follows that these systems enjoy the same desirable approximation properties for directional data as the previous bandlimited and very specific constructions due to Kutyniok and Labate (Trans. Am. Math. Soc. 361:2719-2754, 2009). We also show that the representation formulas we derive are in a sense optimal for the shearlet transform. © 2010 Springer Science+Business Media, LLC.

  16. Landsat Data Continuity Mission

    Science.gov (United States)

    ,

    2012-01-01

    The Landsat Data Continuity Mission (LDCM) is a partnership formed between the National Aeronautics and Space Administration (NASA) and the U.S. Geological Survey (USGS) to place the next Landsat satellite in orbit in January 2013. The Landsat era that began in 1972 will become a nearly 41-year global land record with the successful launch and operation of the LDCM. The LDCM will continue the acquisition, archiving, and distribution of multispectral imagery affording global, synoptic, and repetitive coverage of the Earth's land surfaces at a scale where natural and human-induced changes can be detected, differentiated, characterized, and monitored over time. The mission objectives of the LDCM are to (1) collect and archive medium resolution (30-meter spatial resolution) multispectral image data affording seasonal coverage of the global landmasses for a period of no less than 5 years; (2) ensure that LDCM data are sufficiently consistent with data from the earlier Landsat missions in terms of acquisition geometry, calibration, coverage characteristics, spectral characteristics, output product quality, and data availability to permit studies of landcover and land-use change over time; and (3) distribute LDCM data products to the general public on a nondiscriminatory basis at no cost to the user.

  17. Integrated, Continuous Emulsion Creamer.

    Science.gov (United States)

    Cochrane, Wesley G; Hackler, Amber L; Cavett, Valerie J; Price, Alexander K; Paegel, Brian M

    2017-12-19

    Automated and reproducible sample handling is a key requirement for high-throughput compound screening and currently demands heavy reliance on expensive robotics in screening centers. Integrated droplet microfluidic screening processors are poised to replace robotic automation by miniaturizing biochemical reactions to the droplet scale. These processors must generate, incubate, and sort droplets for continuous droplet screening, passively handling millions of droplets with complete uniformity, especially during the key step of sample incubation. Here, we disclose an integrated microfluidic emulsion creamer that packs ("creams") assay droplets by draining away excess oil through microfabricated drain channels. The drained oil coflows with creamed emulsion and then reintroduces the oil to disperse the droplets at the circuit terminus for analysis. Creamed emulsion assay incubation time dispersion was 1.7%, 3-fold less than other reported incubators. The integrated, continuous emulsion creamer (ICEcreamer) was used to miniaturize and optimize measurements of various enzymatic activities (phosphodiesterase, kinase, bacterial translation) under multiple- and single-turnover conditions. Combining the ICEcreamer with current integrated microfluidic DNA-encoded library bead processors eliminates potentially cumbersome instrumentation engineering challenges and is compatible with assays of diverse target class activities commonly investigated in drug discovery.

  18. Continuously adjustable Pulfrich spectacles

    Science.gov (United States)

    Jacobs, Ken; Karpf, Ron

    2011-03-01

    A number of Pulfrich 3-D movies and TV shows have been produced, but the standard implementation has inherent drawbacks. The movie and TV industries have correctly concluded that the standard Pulfrich 3-D implementation is not a useful 3-D technique. Continuously Adjustable Pulfrich Spectacles (CAPS) is a new implementation of the Pulfrich effect that allows any scene containing movement in a standard 2-D movie, which are most scenes, to be optionally viewed in 3-D using inexpensive viewing specs. Recent scientific results in the fields of human perception, optoelectronics, video compression and video format conversion are translated into a new implementation of Pulfrich 3- D. CAPS uses these results to continuously adjust to the movie so that the viewing spectacles always conform to the optical density that optimizes the Pulfrich stereoscopic illusion. CAPS instantly provides 3-D immersion to any moving scene in any 2-D movie. Without the glasses, the movie will appear as a normal 2-D image. CAPS work on any viewing device, and with any distribution medium. CAPS is appropriate for viewing Internet streamed movies in 3-D.

  19. Passage of delta sleep-inducing peptide (DSIP) across the blood-cerebrospinal fluid barrier

    International Nuclear Information System (INIS)

    Zlokovic, B.V.; Segal, M.B.; Davson, H.; Jankov, R.M.

    1988-01-01

    Unidirectional flux of 125 I-labeled DSIP at the blood-tissue interface of the blood-cerebrospinal fluid (CSF) barrier was studied in the perfused in situ choroid plexuses of the lateral ventricles of the sheep. Arterio-venous loss of 125 I-radioactivity suggested a low-to-moderate permeability of the choroid epithelium to the intact peptide from the blood side. A saturable mechanism with Michaelis-Menten type kinetics with high affinity and very low capacity (approximate values: Kt = 5.0 +/- 0.4 nM; Vmax = 272 +/- 10 fmol.min-1) was demonstrated at the blood-tissue interface of the choroid plexus. The clearance of DSIP from the ventricles during ventriculo-cisternal perfusion in the rabbit indicated no significant flux of the intact peptide out of the CSF. The results suggest that DSIP crosses the blood-CSF barrier, while the system lacks the specific mechanisms for removal from the CSF found with most, if not all, amino acids and several peptides

  20. Tracer kinetics: Modelling of tracer behaviour in nonlinear and nonsteady state systems exemplified by the evaluation of protein turnover in plant organs

    International Nuclear Information System (INIS)

    Winkler, E.

    1991-01-01

    If nonlinear biological processes are investigated by means of tracer experiments they can be modelled with linear kinetic equations (compartment equations) as long as the total system is in a stationary state. But if nonstationary behaviour is included considerations on the kinetics of the individual processes are necessary. Within the range of biological and agricultural investigations especially first order reactions (constant fraction processes), zero order reactions (constant amount process) and saturation reactions (Michaelis-Menten-kinetics) are to be taken into account. A rigorous treatment of data based on system theory can be preceeded by graphic-algebraic procedure which may be more or less uncertain in its results but which can easily be handled. An example is given of methodological considerations concerning the combination of evaluation procedures and the discrimination between different reaction mechanisms. It treats protein turnover in 2 different parts of growing wheat plants investigated by means of an 15 N-tracer experiment. Whereas in a stationary system (upper stalk section) linear tracer equations were sufficient irrespective of the true reaction mechanism, for protein synthesis in the upper leaf as a nonstationary system it was necessary to decide between the hypotheses of a zero order and a first order reaction. In accordance with statements in the literature the unambiguous result was a combination of protein synthesis as a zero order process and of protein degradation as a first order process. (orig.) [de

  1. A fundamental trade-off in covalent switching and its circumvention by enzyme bifunctionality in glucose homeostasis.

    Science.gov (United States)

    Dasgupta, Tathagata; Croll, David H; Owen, Jeremy A; Vander Heiden, Matthew G; Locasale, Jason W; Alon, Uri; Cantley, Lewis C; Gunawardena, Jeremy

    2014-05-09

    Covalent modification provides a mechanism for modulating molecular state and regulating physiology. A cycle of competing enzymes that add and remove a single modification can act as a molecular switch between "on" and "off" and has been widely studied as a core motif in systems biology. Here, we exploit the recently developed "linear framework" for time scale separation to determine the general principles of such switches. These methods are not limited to Michaelis-Menten assumptions, and our conclusions hold for enzymes whose mechanisms may be arbitrarily complicated. We show that switching efficiency improves with increasing irreversibility of the enzymes and that the on/off transition occurs when the ratio of enzyme levels reaches a value that depends only on the rate constants. Fluctuations in enzyme levels, which habitually occur due to cellular heterogeneity, can cause flipping back and forth between on and off, leading to incoherent mosaic behavior in tissues, that worsens as switching becomes sharper. This trade-off can be circumvented if enzyme levels are correlated. In particular, if the competing catalytic domains are on the same protein but do not influence each other, the resulting bifunctional enzyme can switch sharply while remaining coherent. In the mammalian liver, the switch between glycolysis and gluconeogenesis is regulated by the bifunctional 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2). We suggest that bifunctionality of PFK-2/FBPase-2 complements the metabolic zonation of the liver by ensuring coherent switching in response to insulin and glucagon.

  2. Biochemical characteristics and modulation by external and internal factors of aminopeptidase-N activity in the hepatopancreas of a euryhaline burrowing crab.

    Science.gov (United States)

    Michiels, M S; del Valle, J C; López Mañanes, A A

    2015-07-01

    Strikingly, in spite of its physiological importance, information about occurrence, biochemical characteristics and mechanisms of regulation of aminopeptidase-N (APN) in the hepatopancreas of intertidal euryhaline crabs is still lacking. In this work, we determined the occurrence, biochemical characteristics, response to environmental salinity and dopamine of APN in the hepatopancreas of the euryhaline crab Neohelice granulata (Dana 1851) from the open mudflat of Mar Chiquita coastal lagoon (Buenos Aires province, Argentina). APN activity was maximal at pH and temperature range of 7.6-9.0 and 37-45 °C, respectively. APN activity exhibited Michaelis-Menten kinetics (apparent Km = 0.19 ± 0.10 mM) (pH 7.6, 37 °C) and appeared to be sensitive to bestatin (I 50 = 15 mM) and EDTA (I 50 = 9 mM). In crabs acclimated to 10 psu (hyper-regulation conditions) and 37 psu (hypo-regulation conditions), APN activity was about 45 and 160% higher, respectively, than in 35 psu (osmoconformation). APN activity in the hepatopancreas was stimulated in vitro (about 137%) by 10(-4) M dopamine. Higher dopamine concentrations produced a similar extent of increase. The responses of APN activity to salinity and dopamine in vitro suggest the role of APN in digestive adjustments upon hyper and hypo-regulatory conditions and its modulation via direct mechanisms on hepatopancreas by dopamine.

  3. Physiological Response of Plants Grown on Porous Ceramic Tubes

    Science.gov (United States)

    Tsao, David; Okos, Martin

    1997-01-01

    This research involves the manipulation of the root-zone water potential for the purposes of discriminating the rate limiting step in the inorganic nutrient uptake mechanism utilized by higher plants. This reaction sequence includes the pathways controlled by the root-zone conditions such as water tension and gradient concentrations. Furthermore, plant based control mechanisms dictated by various protein productions are differentiated as well. For the nutrients limited by the environmental availability, the kinetics were modeled using convection and diffusion equations. Alternatively, for the nutrients dependent upon enzyme manipulations, the uptakes are modeled using Michaelis-Menten kinetics. In order to differentiate between these various mechanistic steps, an experimental apparatus known as the Porous Ceramic Tube - Nutrient Delivery System (PCT-NDS) was used. Manipulation of the applied suction pressure circulating a nutrient solution through this system imposes a change in the matric component of the water potential. This compensates for the different osmotic components of water potential dictated by nutrient concentration. By maintaining this control over the root-zone conditions, the rate limiting steps in the uptake of the essential nutrients into tomato plants (Lycopersicon esculentum cv. Cherry Elite) were differentiated. Results showed that the uptake of some nutrients were mass transfer limited while others were limited by the enzyme kinetics. Each of these were adequately modeled with calculations and discussions of the parameter estimations provided.

  4. Energetics of glucose metabolism: a phenomenological approach to metabolic network modeling.

    Science.gov (United States)

    Diederichs, Frank

    2010-08-12

    A new formalism to describe metabolic fluxes as well as membrane transport processes was developed. The new flux equations are comparable to other phenomenological laws. Michaelis-Menten like expressions, as well as flux equations of nonequilibrium thermodynamics, can be regarded as special cases of these new equations. For metabolic network modeling, variable conductances and driving forces are required to enable pathway control and to allow a rapid response to perturbations. When applied to oxidative phosphorylation, results of simulations show that whole oxidative phosphorylation cannot be described as a two-flux-system according to nonequilibrium thermodynamics, although all coupled reactions per se fulfill the equations of this theory. Simulations show that activation of ATP-coupled load reactions plus glucose oxidation is brought about by an increase of only two different conductances: a [Ca(2+)] dependent increase of cytosolic load conductances, and an increase of phosphofructokinase conductance by [AMP], which in turn becomes increased through [ADP] generation by those load reactions. In ventricular myocytes, this feedback mechanism is sufficient to increase cellular power output and O(2) consumption several fold, without any appreciable impairment of energetic parameters. Glucose oxidation proceeds near maximal power output, since transformed input and output conductances are nearly equal, yielding an efficiency of about 0.5. This conductance matching is fulfilled also by glucose oxidation of β-cells. But, as a price for the metabolic mechanism of glucose recognition, β-cells have only a limited capability to increase their power output.

  5. Continuous alcoholic fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Smidrkal, M; Nejedly, A

    1956-01-01

    Results are given of investigations on the continuous production of ethanol on a laboratory and on a semi-commercial scale. The suggested devices are particularly described. Under constant conditions the production cycle required 12 to 17 days, the acidity being 4.0 to 415 ml. 0.1 N NaOH/100 ml and the concentration of fermented wort 10.5 to 11%. The maximum production from 1 h of fermentation space during 24 h was 8.67 l of absolute alcohol when the efflux was divided into several basins; when the efflux of sweet wort was collected into one basin only, the maximum production was 7.20 l of absolute alcohol. The amount of alcohol produced was 62.20 l/100 kg sugar.

  6. Spaces of continuous functions

    CERN Document Server

    Groenewegen, G L M

    2016-01-01

    The space C(X) of all continuous functions on a compact space X carries the structure of a normed vector space, an algebra and a lattice. On the one hand we study the relations between these structures and the topology of X, on the other hand we discuss a number of classical results according to which an algebra or a vector lattice can be represented as a C(X). Various applications of these theorems are given. Some attention is devoted to related theorems, e.g. the Stone Theorem for Boolean algebras and the Riesz Representation Theorem. The book is functional analytic in character. It does not presuppose much knowledge of functional analysis; it contains introductions into subjects such as the weak topology, vector lattices and (some) integration theory.

  7. Questioning quantum mechanics

    Science.gov (United States)

    Frappier, Mélanie

    2018-03-01

    A century after its inception, quantum mechanics continues to puzzle us with dead-and-alive cats, waves "collapsing" into particles, and "spooky action at a distance." In his first book, What Is Real?, science writer and astrophysicist Adam Becker sets out to explore why the physics community is still arguing today about quantum mechanics's true meaning.

  8. Continuous spinal anesthesia.

    Science.gov (United States)

    Moore, James M

    2009-01-01

    Continuous spinal anesthesia (CSA) is an underutilized technique in modern anesthesia practice. Compared with other techniques of neuraxial anesthesia, CSA allows incremental dosing of an intrathecal local anesthetic for an indefinite duration, whereas traditional single-shot spinal anesthesia usually involves larger doses, a finite, unpredictable duration, and greater potential for detrimental hemodynamic effects including hypotension, and epidural anesthesia via a catheter may produce lesser motor block and suboptimal anesthesia in sacral nerve root distributions. This review compares CSA with other anesthetic techniques and also describes the history of CSA, its clinical applications, concerns regarding neurotoxicity, and other pharmacologic implications of its use. CSA has seen a waxing and waning of its popularity in clinical practice since its initial description in 1907. After case reports of cauda equina syndrome were reported with the use of spinal microcatheters for CSA, these microcatheters were withdrawn from clinical practice in the United States but continued to be used in Europe with no further neurologic sequelae. Because only large-bore catheters may be used in the United States, CSA is usually reserved for elderly patients out of concern for the risk of postdural puncture headache in younger patients. However, even in younger patients, sometimes the unique clinical benefits and hemodynamic stability involved in CSA outweigh concerns regarding postdural puncture headache. Clinical scenarios in which CSA may be of particular benefit include patients with severe aortic stenosis undergoing lower extremity surgery and obstetric patients with complex heart disease. CSA is an underutilized technique in modern anesthesia practice. Perhaps more accurately termed fractional spinal anesthesia, CSA involves intermittent dosing of local anesthetic solution via an intrathecal catheter. Where traditional spinal anesthesia involves a single injection with a

  9. Mechanisms of Exhaust Pollutants and Plume Formation in Continuous Combustion.

    Science.gov (United States)

    1984-06-01

    device. 4.1.3 Dilute Swirl Combustor (DSC) A swirl-stabilized geometry was developed to address the deficiencies observed with the swirl CBC geometry and...certain deficiencies were apparent in the ability of the model to predict experimental trends. For example: (1) The velocity profiles (Figure lOa) show that...25,000 Re - 50,000 HDF LA 1.1 0.55 Prediction 1.2 0.71 Flow Visualization 0.92 0.66 0 LCF LA 1.2 0.60 Prediction 1.3 0.70 5 J~55 -* - *7 2-- tK2

  10. Mechanical design criteria for continuously operating neutral beams

    International Nuclear Information System (INIS)

    Vosen, S.R.; Bender, D.J.; Fink, J.H.; Lee, J.D.

    1977-01-01

    A schematic of a neutral beam injector is shown. Neutral gas is injected into the ion source, where a discharge ionizes the gas. The ions are drawn from the source by an extractor grid and then accelerated to full energy by the accel grids. After acceleration the ions pass through the neutralizer cell. Once through the neutralizer cell, the beam consists of neutrals and ions. The ions traveling with the beam are space charge neutralized by background electrons. The grid which precedes the direct converter is negatively charged and acts to separate the electrons from the rest of the beam. As a result of the beam's uncompensated space charge the remaining ions spread out from the beam to be collected at the direct converter. This paper presents a generalized analysis which will be useful in determining effects of energy and particle fluxes on the long-term performance of the grids

  11. Growth, chamber building rate and reproduction time of Palaeonummulites venosus (Foraminifera) under natural conditions

    Science.gov (United States)

    Kinoshita, Shunichi; Eder, Wolfgang; Wöger, Julia; Hohenegger, Johann; Briguglio, Antonino

    2017-12-01

    We investigated the symbiont-bearing benthic foraminifer Palaeonummulites venosus to determine the chamber building rate (CBR), test diameter increase rate (DIR), reproduction time and longevity using the `natural laboratory' approach. This is based on the decomposition of monthly obtained frequency distributions of chamber number and test diameter into normally distributed components. Test measurements were taken using MicroCT. The shift of the mean and standard deviation of component parameters during the 15-month investigation period was used to calculate Michaelis-Menten functions applied to estimate the averaged CBR and DIR under natural conditions. The individual dates of birth were estimated using the inverse averaged CBR and the inverse DIR fitted by the individual chamber number or the individual test diameter at the sampling date. Distributions of frequencies and densities (i.e., frequency divided by sediment weight) based on both CBR and DIR revealed continuous reproduction throughout the year with two peaks, a stronger one in June determined as the onset of the summer generation (generation 1) and a weaker one in November determined as the onset of the winter generation (generation 2). This reproduction scheme explains the presence of small and large specimens in the same sample. Longevity, calculated as the maximum difference in days between the individual's birth date and the sampling date, is approximately 1.5 yr, an estimation obtained by using both CBR and DIR.

  12. SACCHARIFICATION OF NATIVE CASSAVA STARCH AT HIGH DRY SOLIDS IN AN ENZYMATIC MEMBRANE REACTOR

    Directory of Open Access Journals (Sweden)

    I Nyoman Widiasa

    2012-02-01

    Full Text Available This study is aimed to develop a novel process scheme for hydrolysis of native cassava starch at high dry solids using an enzymatic membrane reactor (EMR. Firstly, liquefied cassava starch having solids content up to 50% by weight was prepared by three stage liquefactions in a conventional equipment using a commercially available heat stable a-amylase (Termamyl 120L. The liquefied cassava starch was further saccharified in an EMR using glucoamylase (AMG E. By using the developed process scheme, a highly clear hydrolysate with dextrose equivalent (DE approximately 97 could be produced, provided the increase of solution viscosity during the liquefaction was precisely controlled. The excessive space time could result in reduction in conversion degree of starch. Moreover, a residence time distribution study confirmed that the EMR could be modelled as a simple continuous stirred tank reactor (CSTR. Using Lineweaver-Burk analysis, the apparent Michaelis-Menten constant (Km and glucose production rate constant (k2 were 552 (g/l and 4.04 (min-1, respectively. Application of simple CSTR model with those kinetic parameters was quietly appropriate to predict the reactor’s performance at low space time.

  13. The Flavin-Containing Reductase Domain of Cytochrome P450 BM3 Acts as a Surrogate for Mammalian NADPH-P450 Reductase.

    Science.gov (United States)

    Park, Seon-Ha; Kang, Ji-Yeon; Kim, Dong-Hyun; Ahn, Taeho; Yun, Chul-Ho

    2012-11-01

    Cytochrome P450 BM3 (CYP102A1) from Bacillus megaterium is a self-sufficient monooxygenase that consists of a heme domain and FAD/FMN-containing reductase domain (BMR). In this report, the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) by BMR was evaluated as a method for monitoring BMR activity. The electron transfer proceeds from NADPH to BMR and then to BMR substrates, MTT and CTC. MTT and CTC are monotetrazolium salts that form formazans upon reduction. The reduction of MTT and CTC followed classical Michaelis-Menten kinetics (kcat =4120 min(-1), Km =77 μM for MTT and kcat =6580 min(-1), Km =51 μM for CTC). Our continuous assay using MTT and CTC allows the simple, rapid measurement of BMR activity. The BMR was able to metabolize mitomycin C and doxorubicin, which are anticancer drug substrates for CPR, producing the same metabolites as those produced by CPR. Moreover, the BMR was able to interact with CYP1A2 and transfer electrons to promote the oxidation reactions of substrates by CYP1A2 and CYP2E1 in humans. The results of this study suggest the possibility of the utilization of BMR as a surrogate for mammalian CPR.

  14. Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes

    International Nuclear Information System (INIS)

    Bokoch, Michael P.; Devadoss, Anando; Palencsar, Mariela S.; Burgess, James D.

    2004-01-01

    Cholesterol oxidase is immobilized in electrode-supported lipid bilayer membranes. Platinum electrodes are initially modified with a self-assembled monolayer of thiolipid. A vesicle fusion method is used to deposit an outer leaflet of phospholipids onto the thiolipid monolayer forming a thiolipid/lipid bilayer membrane on the electrode surface. Cholesterol oxidase spontaneously inserts into the electrode-supported lipid bilayer membrane from solution and is consequently immobilized to the electrode surface. Cholesterol partitions into the membrane from buffer solutions containing cyclodextrin. Cholesterol oxidase catalyzes the oxidation of cholesterol by molecular oxygen, forming hydrogen peroxide as a product. Amperometric detection of hydrogen peroxide for continuous solution flow experiments are presented, where flow was alternated between cholesterol solution and buffer containing no cholesterol. Steady-state anodic currents were observed during exposures of cholesterol solutions ranging in concentration from 10 to 1000 μM. These data are consistent with the Michaelis-Menten kinetic model for oxidation of cholesterol as catalyzed by cholesterol oxidase immobilized in the lipid bilayer membrane. The cholesterol detection limit is below 1 μM for cholesterol solution prepared in buffered cyclodextrin. The response of the electrodes to low density lipoprotein solutions is increased upon addition of cyclodextrin. Evidence for adsorption of low density lipoprotein to the electrode surface is presented

  15. Eugenol nanocapsule for enhanced therapeutic activity against periodontal infections.

    Science.gov (United States)

    Pramod, Kannissery; Aji Alex, M R; Singh, Manisha; Dang, Shweta; Ansari, Shahid H; Ali, Javed

    2016-01-01

    Eugenol is a godsend to dental care due to its analgesic, local anesthetic, and anti-inflammatory and antibacterial effects. The aim of the present research work was to prepare, characterize and evaluate eugenol-loaded nanocapsules (NCs) against periodontal infections. Eugenol-loaded polycaprolactone (PCL) NCs were prepared by solvent displacement method. The nanometric size of the prepared NCs was confirmed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The in vitro drug release was found to follow a biphasic pattern and followed Michaelis-Menten like model. The percentage cell viability values near to 100 in the cell viability assay indicated that the NCs are not cytotoxic. In the in vivo studies, the eugenol NC group displayed significant difference in the continuity of epithelium of the interdental papilla in comparison to the untreated, pure eugenol and placebo groups. The in vivo performance of the eugenol-loaded NCs using ligature-induced periodontitis model in rats indicated that eugenol-loaded NCs could prevent septal bone resorption in periodontitis. On the basis of our research findings it could be concluded that eugenol-loaded PCL NCs could serve as a novel colloidal drug delivery system for enhanced therapeutic activity of eugenol in the treatment of periodontal infections.

  16. Kinetics of the removal of mono-chlorobenzene vapour from waste gases using a trickle bed air biofilter.

    Science.gov (United States)

    Mathur, Anil K; Sundaramurthy, J; Balomajumder, C

    2006-10-11

    The performance of a trickle bed air biofilter (TBAB) in the removal of mono-chlorobenzene (MCB) was evaluated in concentrations varying from 0.133 to 7.187 g m(-3) and at empty bed residence time (EBRT) varying from 37.7 to 188.52 s. More than 90% removal efficiency in the trickle bed air biofilter was achieved for the inlet MCB concentration up to 1.069 g m(-3) and EBRT less than 94.26 s. The trickle bed air biofilter was constructed with coal packing material, inoculated with a mixed consortium of activated sludge obtained from sewage treatment plant. The continuous performance of the removal of MCB in the trickle bed air biofilter was monitored for various gas concentrations, gas flow rates, and empty bed residence time. The experiment was conducted for a period of 75 days. The trickle bed air biofilter degrading MCB with an average elimination capacity of 80 g m(-3) h(-1) was obtained. The effect of starvation was also studied. After starvation period of 8 days, the degradation was low but recovered within a short period of time. Using macrokinetic determination method, the Michaelis-Menten kinetic constant K(m) and maximum reaction rate, r(max) evaluated as 0.121 g m(-3) s(-1) and 7.45 g m(-3), respectively.

  17. Hysteresis response of daytime net ecosystem exchange during drought

    Directory of Open Access Journals (Sweden)

    N. Pingintha

    2010-03-01

    Full Text Available Continuous measurements of net ecosystem CO2 exchange (NEE using the eddy-covariance method were made over an agricultural ecosystem in the southeastern US. During optimum environmental conditions, photosynthetically active radiation (PAR was the primary driver controlling daytime NEE, accounting for as much as 67 to 89% of the variation in NEE. However, soil water content became the dominant factor limiting the NEE-PAR response during the peak growth stage. NEE was significantly depressed when high PAR values coincided with very low soil water content. The presence of a counter-clockwise hysteresis of daytime NEE with PAR was observed during periods of water stress. This is a result of the stomatal closure control of photosynthesis at high vapor pressure deficit and enhanced respiration at high temperature. This result is significant since this hysteresis effect limits the range of applicability of the Michaelis-Menten equation and other related expressions in the determination of daytime NEE as a function of PAR. The systematic presence of hysteresis in the response of NEE to PAR suggests that the gap-filling technique based on a non-linear regression approach should take into account the presence of water-limited field conditions. Including this step is therefore likely to improve current evaluation of ecosystem response to increased precipitation variability arising from climatic changes.

  18. Growth, chamber building rate and reproduction time of Palaeonummulites venosus under natural conditions.

    Science.gov (United States)

    Kinoshita, Shunichi; Eder, Wolfgang; Wöger, Julia; Hohenegger, Johann; Briguglio, Antonino

    2017-04-01

    Investigations on Palaeonummulites venosus using the natural laboratory approach for determining chamber building rate, test diameter increase rate, reproduction time and longevity is based on the decomposition of monthly obtained frequency distributions based on chamber number and test diameter into normal-distributed components. The shift of the component parameters 'mean' and 'standard deviation' during the investigation period of 15 months was used to calculate Michaelis-Menten functions applied to estimate the averaged chamber building rate and diameter increase rate under natural conditions. The individual dates of birth were estimated using the inverse averaged chamber building rate and the inverse diameter increase rate fitted by the individual chamber number or the individual test diameter at the sampling date. Distributions of frequencies and densities (i.e. frequency divided by sediment weight) based on chamber building rate and diameter increase rate resulted both in a continuous reproduction through the year with two peaks, the stronger in May /June determined as the beginning of the summer generation (generation1) and the weaker in November determined as the beginning of the winter generation (generation 2). This reproduction scheme explains the existence of small and large specimens in the same sample. Longevity, calculated as the maximum difference in days between the individual's birth date and the sampling date seems to be round about one year, obtained by both estimations based on the chamber building rate and the diameter increase rate.

  19. Preparation of reusable bioreactors using reversible immobilization of enzyme on monolithic porous polymer support with attached gold nanoparticles.

    Science.gov (United States)

    Lv, Yongqin; Lin, Zhixing; Tan, Tianwei; Svec, Frantisek

    2014-01-01

    Porcine lipase has been reversibly immobilized on a monolithic polymer support containing thiol functionalities prepared within confines of a fused silica capillary and functionalized with gold nanoparticles. Use of gold nanoparticles enabled rejuvenation of the activity of the deactivated reactor simply by stripping the inactive enzyme from the nanoparticles using 2-mercaptoethanol and subsequent immobilization of fresh lipase. This flow through enzymatic reactor was then used to catalyze the hydrolysis of glyceryl tributyrate (tributyrin). The highest activity was found within a temperature range of 37-40°C. The reaction kinetics is characterized by Michaelis-Menten constant, Km  = 10.9 mmol/L, and maximum reaction rate, Vmax  = 5.0 mmol/L min. The maximum reaction rate for the immobilized enzyme is 1,000 times faster compared to lipase in solution. The fast reaction rate enabled to achieve 86.7% conversion of tributyrin in mere 2.5 min and an almost complete conversion in 10 min. The reactor lost only less than 10% of its activity even after continuous pumping through it a solution of substrate equaling 1,760 reactor volumes. Finally, potential application of this enzymatic reactor was demonstrated with the transesterification of triacylglycerides from kitchen oil to fatty acid methyl esters thus demonstrating the ability of the reactor to produce biodiesel. © 2013 Wiley Periodicals, Inc.

  20. Kinetics of butyrate, acetate, and hydrogen metabolism in a thermophilic, anaerobic, butyrate-degrading triculture.

    Science.gov (United States)

    Ahring, B K; Westermann, P

    1987-02-01

    Kinetics of butyrate, acetate, and hydrogen metabolism were determined with butyrate-limited, chemostat-grown tricultures of a thermophilic butyrate-utilizing bacterium together with Methanobacterium thermoautotrophicum and the TAM organism, a thermophilic acetate-utilizing methanogenic rod. Kinetic parameters were determined from progress curves fitted to the integrated form of the Michaelis-Menten equation. The apparent half-saturation constants, K(m), for butyrate, acetate, and dissolved hydrogen were 76 muM, 0.4 mM, and 8.5 muM, respectively. Butyrate and hydrogen were metabolized to a concentration of less than 1 muM, whereas acetate uptake usually ceased at a concentration of 25 to 75 muM, indicating a threshold level for acetate uptake. No significant differences in K(m) values for butyrate degradation were found between chemostat- and batch-grown tricultures, although the maximum growth rate was somewhat higher in the batch cultures in which the medium was supplemented with yeast extract. Acetate utilization was found to be the rate-limiting reaction for complete degradation of butyrate to methane and carbon dioxide in continuous culture. Increasing the dilution rate resulted in a gradual accumulation of acetate. The results explain the low concentrations of butyrate and hydrogen normally found during anaerobic digestion and the observation that acetate is the first volatile fatty acid to accumulate upon a decrease in retention time or increase in organic loading of a digestor.

  1. Evaluation of sources of variation on in vitro fermentation kinetics of feedstuffs in a gas production system.

    Science.gov (United States)

    Keim, Juan P; Alvarado-Gilis, Christian; Arias, Rodrigo A; Gandarillas, Mónica; Cabanilla, Jaime

    2017-10-01

    The aim of this study was to evaluate the effect of different sources of variation in gas production technique on the in vitro gas production kinetics of feedstuffs. Triplicates of commercial concentrate, grass silage, grass hay and grass pasture were incubated in three experiments: experiment 1 assessed two agitation methods; experiment 2 evaluated different rumen inocula (pooled or different donor cows for each incubation run); and experiment 3 used Goering-Van Soest or Mould buffers for media preparation. Gas production data were fitted into the Michaelis-Menten model and then subjected to analysis of variance. Gas production (GP) at 48 h and asymptote gas production (A) were lower when bottles were continuously under horizontal movement. Time to produce half and 75% of A, and A were affected by rumen inocula, while buffer type affected time to produce half and 25% of A and GP. No interactions between substrates and sources of variation were observed, suggesting that the effects of substrates on GP parameters were not modified. It is concluded that comparison of numerical data from in vitro experiments that follow different protocols must be done carefully. However, the ranking of different substrates is more robust and less affected by the sources of variation. © 2017 Japanese Society of Animal Science.

  2. A Study on Pharmacokinetics of Bosentan with Systems Modeling, Part 2: Prospectively Predicting Systemic and Liver Exposure in Healthy Subjects.

    Science.gov (United States)

    Li, Rui; Kimoto, Emi; Niosi, Mark; Tess, David A; Lin, Jian; Tremaine, Larry M; Di, Li

    2018-04-01

    Predicting human pharmacokinetics of novel compounds is a critical step in drug discovery and clinical study design but continues to be a challenging task for hepatic transporter substrates, particularly in predicting their liver exposures. In this study, using bosentan as an example, we prospectively predicted systemic exposure and the (pseudo) steady-state unbound liver-to-unbound plasma ratio ( K p uu ) in healthy subjects using 1) a mechanistic approach solely based on in vitro hepatocyte assays and 2) an approach based on hepatic process rates from monkey in vivo data but Michaelis-Menten constants from in vitro data. Both methods reasonably match the observed human systemic time course data, but the second method leads to better prediction accuracy. In addition, the second method can predict a human K p uu value that is close to the value deduced using clinical data. We also generated rat and monkey liver K p uu values in terminal studies. However, these directly measured animal values are different from the deduced human value. Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics.

  3. Mechanics without mechanisms

    Science.gov (United States)

    Eisenthal, Joshua

    2018-05-01

    At the time of Heinrich Hertz's premature death in 1894, he was regarded as one of the leading scientists of his generation. However, the posthumous publication of his treatise in the foundations of physics, Principles of Mechanics, presents a curious historical situation. Although Hertz's book was widely praised and admired, it was also met with a general sense of dissatisfaction. Almost all of Hertz's contemporaries criticized Principles for the lack of any plausible way to construct a mechanism from the "hidden masses" that are particularly characteristic of Hertz's framework. This issue seemed especially glaring given the expectation that Hertz's work might lead to a model of the underlying workings of the ether. In this paper I seek an explanation for why Hertz seemed so unperturbed by the difficulties of constructing such a mechanism. In arriving at this explanation, I explore how the development of Hertz's image-theory of representation framed the project of Principles. The image-theory brings with it an austere view of the "essential content" of mechanics, only requiring a kind of structural isomorphism between symbolic representations and target phenomena. I argue that bringing this into view makes clear why Hertz felt no need to work out the kinds of mechanisms that many of his readers looked for. Furthermore, I argue that a crucial role of Hertz's hypothesis of hidden masses has been widely overlooked. Far from acting as a proposal for the underlying structure of the ether, I show that Hertz's hypothesis ruled out knowledge of such underlying structure.

  4. Continuous process electrorefiner

    Science.gov (United States)

    Herceg, Joseph E [Naperville, IL; Saiveau, James G [Hickory Hills, IL; Krajtl, Lubomir [Woodridge, IL

    2006-08-29

    A new device is provided for the electrorefining of uranium in spent metallic nuclear fuels by the separation of unreacted zirconium, noble metal fission products, transuranic elements, and uranium from spent fuel rods. The process comprises an electrorefiner cell. The cell includes a drum-shaped cathode horizontally immersed about half-way into an electrolyte salt bath. A conveyor belt comprising segmented perforated metal plates transports spent fuel into the salt bath. The anode comprises the conveyor belt, the containment vessel, and the spent fuel. Uranium and transuranic elements such as plutonium (Pu) are oxidized at the anode, and, subsequently, the uranium is reduced to uranium metal at the cathode. A mechanical cutter above the surface of the salt bath removes the deposited uranium metal from the cathode.

  5. Mechanical lift of profile

    Energy Technology Data Exchange (ETDEWEB)

    O`Mahoney, H.

    1999-04-01

    Continuous ship unloaders (CSUs) are continuing to become more popular than grab unloaders for dealing with greater capacities of coal. The article surveys current major manufacturers` equipment. Krupp Foerdertechnik, for example, offers seven mechanical ship unloaders, including CSU with scraper chain or L-shaped bucket-elevators, CSU with vertical screw conveyor and horizontal screw-type feeder conveyors. CSU with bucket-elevator and feeding scraper and a continuous barge unloader with bucket elevator, BMH Marine Siwertell continues to be the benchmark for technology advances. HW Carlsan has recently entered the field with a new screw-type ship unloader. 4 photos.

  6. The effects of carbon nanotube addition and oxyfluorination on the glucose-sensing capabilities of glucose oxidase-coated carbon fiber electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Im, Ji Sun; Yun, Jumi; Kim, Jong Gu [Department of Fine Chemical Engineering and Applied Chemistry, BK21-E2 M, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Bae, Tae-Sung [Department of Fine Chemical Engineering and Applied Chemistry, BK21-E2 M, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Korea Basic Science Institute (KBSI), Jeonju 561-756 (Korea, Republic of); Lee, Young-Seak, E-mail: youngslee@cnu.ac.kr [Department of Fine Chemical Engineering and Applied Chemistry, BK21-E2 M, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

    2012-01-15

    Glucose-sensing electrodes were constructed from carbon fibers by electrospinning and heat treatment. By controlling the pore size, the specific surface area and pore volume of the electrospun carbon fibers were increased for efficient immobilization of the glucose oxidase. Carbon nanotubes were embedded as an electrically conductive additive to improve the electrical property of the porous carbon fibers. In addition, the surface of the porous carbon fibers was modified with hydrophilic functional groups by direct oxyfluorination to increase the affinity between the hydrophobic carbon surface and the hydrophilic glucose oxidase molecules. The porosity of the carbon fibers was improved significantly with approximately 28- and 35-fold increases in the specific surface area and pore volume, respectively. The number of chemical bonds between carbon and oxygen were increased with higher oxygen content during oxyfluorination based on the X-ray photoelectron spectroscopy results. Glucose sensing was carried out by current voltagram and amperometric methods. A high-performance glucose sensor was obtained with high sensitivity and rapid response time as a result of carbon nanotube addition, physical activation and surface modification. The mechanism of the highly sensitive prepared glucose sensor was modeled by an enzyme kinetics study using the Michaelis-Menten equation.

  7. Annealing helicase HARP closes RPA-stabilized DNA bubbles non-processively.

    Science.gov (United States)

    Burnham, Daniel R; Nijholt, Bas; De Vlaminck, Iwijn; Quan, Jinhua; Yusufzai, Timur; Dekker, Cees

    2017-05-05

    We investigate the mechanistic nature of the Snf2 family protein HARP, mutations of which are responsible for Schimke immuno-osseous dysplasia. Using a single-molecule magnetic tweezers assay, we construct RPA-stabilized DNA bubbles within torsionally constrained DNA to investigate the annealing action of HARP on a physiologically relevant substrate. We find that HARP closes RPA-stabilized bubbles in a slow reaction, taking on the order of tens of minutes for ∼600 bp of DNA to be re-annealed. The data indicate that DNA re-anneals through the removal of RPA, which is observed as clear steps in the bubble-closing traces. The dependence of the closing rate on both ionic strength and HARP concentration indicates that removal of RPA occurs via an association-dissociation mechanism where HARP does not remain associated with the DNA. The enzyme exhibits classical Michaelis-Menten kinetics and acts cooperatively with a Hill coefficient of 3 ± 1. Our work also allows the determination of some important features of RPA-bubble structures at low supercoiling, including the existence of multiple bubbles and that RPA molecules are mis-registered on the two strands. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  8. Brain glucose transport and phosphorylation under acute insulin-induced hypoglycemia in mice: an 18F-FDG PET study.

    Science.gov (United States)

    Alf, Malte F; Duarte, João M N; Schibli, Roger; Gruetter, Rolf; Krämer, Stefanie D

    2013-12-01

    We addressed the questions of how cerebral glucose transport and phosphorylation change under acute hypoglycemia and what the underlying mechanisms of adaptation are. Quantitative (18)F-FDG PET combined with the acquisition of real-time arterial input function was performed on mice. Hypoglycemia was induced and maintained by insulin infusion. PET data were analyzed with the 2-tissue-compartment model for (18)F-FDG, and the results were evaluated with Michaelis-Menten saturation kinetics. Glucose clearance from plasma to brain (K1,glc) and the phosphorylation rate constant increased with decreasing plasma glucose (Gp), in particular at a Gp of less than 2.5 mmol/L. Estimated cerebral glucose extraction ratios taking into account an increased cerebral blood flow (CBF) at a Gp of less than 2 mmol/L were between 0.14 and 0.79. CBF-normalized K1,glc values were in agreement with saturation kinetics. Phosphorylation rate constants indicated intracellular glucose depletion at a Gp of less than 2-3 mmol/L. When brain regions were compared, glucose transport under hypoglycemia was lowest in the hypothalamus. Alterations in glucose transport and phosphorylation, as well as intracellular glucose depletion, under acute hypoglycemia can be modeled by saturation kinetics taking into account an increase in CBF. Distinct transport kinetics in the hypothalamus may be involved in its glucose-sensing function.

  9. Structural Basis of Binding and Rationale for the Potent Urease Inhibitory Activity of Biscoumarins

    Science.gov (United States)

    Lodhi, Muhammad Arif; Choudhary, Muhammad Iqbal; Lodhi, Atif; Ul-Haq, Zaheer; Jalil, Saima; Nawaz, Sarfraz Ahmad; Khan, Khalid Mohammed; Iqbal, Sajid; Rahman, Atta-ur

    2014-01-01

    Urease belongs to a family of highly conserved urea-hydrolyzing enzymes. A common feature of these enzymes is the presence of two Lewis acid nickel ions and reactive cysteine residue in the active sites. In the current study we examined a series of biscoumarins 1–10 for their mechanisms of inhibition with the nickel containing active sites of Jack bean and Bacillus pasteurii ureases. All these compounds competitively inhibited Jack bean urease through interaction with the nickel metallocentre, as deduced from Michaelis-Menten kinetics, UV-visible absorbance spectroscopic, and molecular docking simulation studies. Some of the compounds behaved differently in case of Bacillus pasteurii urease. We conducted the enzyme kinetics, UV-visible spectroscopy, and molecular docking results in terms of the known protein structure of the enzyme. We also evaluated possible molecular interpretations for the site of biscoumarins binding and found that phenyl ring is the major active pharmacophore. The excellent in vitro potency and selectivity profile of the several compounds described combined with their nontoxicity against the human cells and plants suggest that these compounds may represent a viable lead series for the treatment of urease associated problems. PMID:25295281

  10. Oleamide synthesizing activity from rat kidney: identification as cytochrome c.

    Science.gov (United States)

    Driscoll, William J; Chaturvedi, Shalini; Mueller, Gregory P

    2007-08-03

    Oleamide (cis-9-octadecenamide) is the prototype member of an emerging class of lipid signaling molecules collectively known as the primary fatty acid amides. Current evidence suggests that oleamide participates in the biochemical mechanisms underlying the drive to sleep, thermoregulation, and antinociception. Despite the potential importance of oleamide in these physiologic processes, the biochemical pathway for its synthesis in vivo has not been established. We report here the discovery of an oleamide synthetase found in rat tissues using [(14)C]oleoyl-CoA and ammonium ion. Hydrogen peroxide was subsequently found to be a required cofactor. The enzyme displayed temperature and pH optima in the physiologic range, a remarkable resistance to proteolysis, and specificity for long-chain acyl-CoA substrates. The reaction demonstrated Michaelis-Menten kinetics with a K(m) for oleoyl-CoA of 21 microm. Proteomic, biochemical, and immunologic analyses were used to identify the source of the oleamide synthesizing activity as cytochrome c. This identification was based upon peptide mass fingerprinting of isolated synthase protein, a tight correlation between enzymatic activity and immunoreactivity for cytochrome c, and identical functional properties shared by the tissue-derived synthetase and commercially obtained cytochrome c. The ability of cytochrome c to catalyze the formation of oleamide experimentally raises the possibility that cytochrome c may mediate oleamide biosynthesis in vivo.

  11. Relation of cardiac energy metabolism to workload studied with 31P NMR

    International Nuclear Information System (INIS)

    Ligeti, L.; Osbakken, M.; Clark, B.J.; Schnall, M.; Bolinger, L.; Subramanian, H.; Leigh, J.S.; Chance, B.

    1986-01-01

    The relationship between myocardial work and concentration of mediators of oxidative phosphorylation (ATP, PCr, Pi) was studied in vivo in 6 dogs and 4 cats with 31 P NMR. The heart was exposed via thoracotomy for placement of surface coils and pacing electrodes. Work (defined as heart rate X blood pressure product) was increased by pacing the heart from 2Hz (rest) to 5Hz. In cats, an increase in work from 1.9 x 10 4 +/- .32 to 2.4 x 10 4 +/- .08 was associated with an increase in Pi/PCr ratio from .29 +/- .08 to .68 +/- .33; in dogs, work increase from 1.74 x 10 4 .82 to 3.4 x 10 4 +/- .84 did not cause significant change in Pi/PCr (.29 +/- .15 to .30 +/- .17). If these data are analyzed via the Michaelis-Menten algorithm, the cat heart can be considered to be set closer to V/sub max/ and the dog heart set closer to V/sub o/ (i.e. having a larger metabolic reserve). The difference between the 2 species could be due to microvascular and/or metabolic control mechanisms. Delineation of the different metabolic responses to work in these animal models may be helpful in understanding the physiological basis of heart disease

  12. Lipase-catalyzed synthesis of palmitanilide: Kinetic model and antimicrobial activity study.

    Science.gov (United States)

    Liu, Kuan-Miao; Liu, Kuan-Ju

    2016-01-01

    Enzymatic syntheses of fatty acid anilides are important owing to their wide range of industrial applications in detergents, shampoo, cosmetics, and surfactant formulations. The amidation reaction of Mucor miehei lipase Lipozyme IM20 was investigated for direct amidation of triacylglycerol in organic solvents. The process parameters (reaction temperature, substrate molar ratio, enzyme amount) were optimized to achieve the highest yield of anilide. The maximum yield of palmitanilide (88.9%) was achieved after 24 h of reaction at 40 °C at an enzyme concentration of 1.4% (70 mg). Kinetics of lipase-catalyzed amidation of aniline with tripalmitin has been investigated. The reaction rate could be described in terms of the Michaelis-Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. The kinetic constants were estimated by using non-linear regression method using enzyme kinetic modules. The enzyme operational stability study showed that Lipozyme IM20 retained 38.1% of the initial activity for the synthesis of palmitanilide (even after repeated use for 48 h). Palmitanilide, a fatty acid amide, exhibited potent antimicrobial activity toward Bacillus cereus. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Process Integration for the Disruption of Candida guilliermondii Cultivated in Rice Straw Hydrolysate and Recovery of Glucose-6-Phosphate Dehydrogenase by Aqueous Two-Phase Systems.

    Science.gov (United States)

    Gurpilhares, Daniela B; Pessoa, Adalberto; Roberto, Inês C

    2015-07-01

    Remaining cells of Candida guilliermondii cultivated in hemicellulose-based fermentation medium were used as intracellular protein source. Recovery of glucose-6-phosphate dehydrogenase (G6PD) was attained in conventional aqueous two-phase systems (ATPS) was compared with integrated process involving mechanical disruption of cells followed by ATPS. Influences of polyethylene glycol molar mass (M PEG) and tie line lengths (TLL) on purification factor (PF), yields in top (Y T ) and bottom (Y B ) phases and partition coefficient (K) were evaluated. First scheme resulted in 65.9 % enzyme yield and PF of 2.16 in salt-enriched phase with clarified homogenate (M PEG 1500 g mol(-1), TLL 40 %); Y B of 75.2 % and PF B of 2.9 with unclarified homogenate (M PEG 1000 g mol(-1), TLL 35 %). The highest PF value of integrated process was 2.26 in bottom phase (M PEG 1500 g mol(-1), TLL 40 %). In order to optimize this response, a quadratic model was predicted for the response PFB for process integration. Maximum response achieved was PFB = 3.3 (M PEG 1500 g mol(-1), TLL 40 %). Enzyme characterization showed G6P Michaelis-Menten constant (K M ) equal 0.07-0.05, NADP(+) K M 0.02-1.98 and optimum temperature 70 °C, before and after recovery. Overall, our data confirmed feasibility of disruption/extraction integration for single-step purification of intracellular proteins from remaining yeast cells.

  14. A physiologically based kinetic model for bacterial sulfide oxidation.

    Science.gov (United States)

    Klok, Johannes B M; de Graaff, Marco; van den Bosch, Pim L F; Boelee, Nadine C; Keesman, Karel J; Janssen, Albert J H

    2013-02-01

    In the biotechnological process for hydrogen sulfide removal from gas streams, a variety of oxidation products can be formed. Under natron-alkaline conditions, sulfide is oxidized by haloalkaliphilic sulfide oxidizing bacteria via flavocytochrome c oxidoreductase. From previous studies, it was concluded that the oxidation-reduction state of cytochrome c is a direct measure for the bacterial end-product formation. Given this physiological feature, incorporation of the oxidation state of cytochrome c in a mathematical model for the bacterial oxidation kinetics will yield a physiologically based model structure. This paper presents a physiologically based model, describing the dynamic formation of the various end-products in the biodesulfurization process. It consists of three elements: 1) Michaelis-Menten kinetics combined with 2) a cytochrome c driven mechanism describing 3) the rate determining enzymes of the respiratory system of haloalkaliphilic sulfide oxidizing bacteria. The proposed model is successfully validated against independent data obtained from biological respiration tests and bench scale gas-lift reactor experiments. The results demonstrate that the model is a powerful tool to describe product formation for haloalkaliphilic biomass under dynamic conditions. The model predicts a maximum S⁰ formation of about 98 mol%. A future challenge is the optimization of this bioprocess by improving the dissolved oxygen control strategy and reactor design. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. On enzyme kinetic parameters modification of gamma irradiation

    International Nuclear Information System (INIS)

    Ferdes, O.S.; Ferdes, M.; Turcu, G.R.

    1993-01-01

    To elucidate the molecular mechanisms of gamma-ray action on biomolecules there were investigated the modifications in activity and other kinetic parameters for some enzymes irradiated in pure dry state at relative high doses. There were considered bacterial and fungal α-amylases, glucoamylase and Mucor sp. protease irradiated by a 60 Co gamma-ray source in the dose range 1.0-30.0 kGy, at different dose-rates between 0.5-2.0 kGy/h, at room temperature. Considering the enzyme inactivation in this dose range, the dose-effect relationships have an expected form and depend on the irradiation conditions but not significantly on the dose rate. The catalytic properties of enzymes were modified by irradiation. By usual methods it is evidenced a direct correlation between the enzymatic activities, Michaelis-Menten constant, K m , reaction velocities, v, and the irradiation dose. These experimental findings can support a self-consistent theoretical approach on biophysical radiation action on biological active molecules like enzymes. At the same time, some enzyme behaviour to irradiation could be considered like a good biological indicator of radiation response. (Author) 4 Figs., 19 Refs

  16. Emergence of a code in the polymerization of amino acids along RNA templates.

    Directory of Open Access Journals (Sweden)

    Jean Lehmann

    2009-06-01

    Full Text Available The origin of the genetic code in the context of an RNA world is a major problem in the field of biophysical chemistry. In this paper, we describe how the polymerization of amino acids along RNA templates can be affected by the properties of both molecules. Considering a system without enzymes, in which the tRNAs (the translation adaptors are not loaded selectively with amino acids, we show that an elementary translation governed by a Michaelis-Menten type of kinetics can follow different polymerization regimes: random polymerization, homopolymerization and coded polymerization. The regime under which the system is running is set by the relative concentrations of the amino acids and the kinetic constants involved. We point out that the coding regime can naturally occur under prebiotic conditions. It generates partially coded proteins through a mechanism which is remarkably robust against non-specific interactions (mismatches between the adaptors and the RNA template. Features of the genetic code support the existence of this early translation system.

  17. Characterization of inorganic phosphate transport in the triple-negative breast cancer cell line, MDA-MB-231.

    Science.gov (United States)

    Russo-Abrahão, Thais; Lacerda-Abreu, Marco Antônio; Gomes, Tainá; Cosentino-Gomes, Daniela; Carvalho-de-Araújo, Ayra Diandra; Rodrigues, Mariana Figueiredo; Oliveira, Ana Carolina Leal de; Rumjanek, Franklin David; Monteiro, Robson de Queiroz; Meyer-Fernandes, José Roberto

    2018-01-01

    Recent studies demonstrate that interstitial inorganic phosphate is significantly elevated in the breast cancer microenvironment as compared to normal tissue. In addition it has been shown that breast cancer cells express high levels of the NaPi-IIb carrier (SLC34A2), suggesting that this carrier may play a role in breast cancer progression. However, the biochemical behavior of inorganic phosphate (Pi) transporter in this cancer type remains elusive. In this work, we characterize the kinetic parameters of Pi transport in the aggressive human breast cancer cell line, MDA-MB-231, and correlated Pi transport with cell migration and adhesion. We determined the influence of sodium concentration, pH, metabolic inhibitors, as well as the affinity for inorganic phosphate in Pi transport. We observed that the inorganic phosphate is dependent on sodium transport (K0,5 value = 21.98 mM for NaCl). Furthermore, the transport is modulated by different pH values and increasing concentrations of Pi, following the Michaelis-Menten kinetics (K0,5 = 0.08 mM Pi). PFA, monensin, furosemide and ouabain inhibited Pi transport, cell migration and adhesion. Taken together, these results showed that the uptake of Pi in MDA-MB-231 cells is modulated by sodium and by regulatory mechanisms of intracellular sodium gradient. General Significance: Pi transport might be regarded as a potential target for therapy against tumor progression.

  18. Functional and Structural Characterization of a (+)-Limonene Synthase from Citrus sinensis.

    Science.gov (United States)

    Morehouse, Benjamin R; Kumar, Ramasamy P; Matos, Jason O; Olsen, Sarah Naomi; Entova, Sonya; Oprian, Daniel D

    2017-03-28

    Terpenes make up the largest and most diverse class of natural compounds and have important commercial and medical applications. Limonene is a cyclic monoterpene (C 10 ) present in nature as two enantiomers, (+) and (-), which are produced by different enzymes. The mechanism of production of the (-)-enantiomer has been studied in great detail, but to understand how enantiomeric selectivity is achieved in this class of enzymes, it is important to develop a thorough biochemical description of enzymes that generate (+)-limonene, as well. Here we report the first cloning and biochemical characterization of a (+)-limonene synthase from navel orange (Citrus sinensis). The enzyme obeys classical Michaelis-Menten kinetics and produces exclusively the (+)-enantiomer. We have determined the crystal structure of the apoprotein in an "open" conformation at 2.3 Å resolution. Comparison with the structure of (-)-limonene synthase (Mentha spicata), which is representative of a fully closed conformation (Protein Data Bank entry 2ONG ), reveals that the short H-α1 helix moves nearly 5 Å inward upon substrate binding, and a conserved Tyr flips to point its hydroxyl group into the active site.

  19. Direct Visualization of Barrier Crossing Dynamics in a Driven Optical Matter System.

    Science.gov (United States)

    Figliozzi, Patrick; Peterson, Curtis W; Rice, Stuart A; Scherer, Norbert F

    2018-04-25

    A major impediment to a more complete understanding of barrier crossing and other single-molecule processes is the inability to directly visualize the trajectories and dynamics of atoms and molecules in reactions. Rather, the kinetics are inferred from ensemble measurements or the position of a transducer ( e. g., an AFM cantilever) as a surrogate variable. Direct visualization is highly desirable. Here, we achieve the direct measurement of barrier crossing trajectories by using optical microscopy to observe position and orientation changes of pairs of Ag nanoparticles, i. e. passing events, in an optical ring trap. A two-step mechanism similar to a bimolecular exchange reaction or the Michaelis-Menten scheme is revealed by analysis that combines detailed knowledge of each trajectory, a statistically significant number of repetitions of the passing events, and the driving force dependence of the process. We find that while the total event rate increases with driving force, this increase is due to an increase in the rate of encounters. There is no drive force dependence on the rate of barrier crossing because the key motion for the process involves a random (thermal) radial fluctuation of one particle allowing the other to pass. This simple experiment can readily be extended to study more complex barrier crossing processes by replacing the spherical metal nanoparticles with anisotropic ones or by creating more intricate optical trapping potentials.

  20. A simple theory of motor protein kinetics and energetics. II.

    Science.gov (United States)

    Qian, H

    2000-01-10

    A three-state stochastic model of motor protein [Qian, Biophys. Chem. 67 (1997) pp. 263-267] is further developed to illustrate the relationship between the external load on an individual motor protein in aqueous solution with various ATP concentrations and its steady-state velocity. A wide variety of dynamic motor behavior are obtained from this simple model. For the particular case of free-load translocation being the most unfavorable step within the hydrolysis cycle, the load-velocity curve is quasi-linear, V/Vmax = (cF/Fmax-c)/(1-c), in contrast to the hyperbolic relationship proposed by A.V. Hill for macroscopic muscle. Significant deviation from the linearity is expected when the velocity is less than 10% of its maximal (free-load) value--a situation under which the processivity of motor diminishes and experimental observations are less certain. We then investigate the dependence of load-velocity curve on ATP (ADP) concentration. It is shown that the free load Vmax exhibits a Michaelis-Menten like behavior, and the isometric Fmax increases linearly with ln([ATP]/[ADP]). However, the quasi-linear region is independent of the ATP concentration, yielding an apparently ATP-independent maximal force below the true isometric force. Finally, the heat production as a function of ATP concentration and external load are calculated. In simple terms and solved with elementary algebra, the present model provides an integrated picture of biochemical kinetics and mechanical energetics of motor proteins.

  1. Enzymatic Synthesis of Furfuryl Alcohol Ester with Oleic Acid by Candida antarctica Lipase B and Its Kinetic Study

    Science.gov (United States)

    Sengupta, Avery; Dey, Tanmoy; Ghosh, Mahua; Ghosh, Jaydip; Ghosh, Santinath

    2012-08-01

    This study investigated the successful enzymatic production of furfuryl oleate and its detailed kinetic study by Michaelis-Menten model. Esterification of oleic acid and furfuryl alcohol by Candida antarctica lipase B (Novozym 435 preparation) in a solvent free system was studied in the present work at 1:1 molar ratio of furfuryl alcohol and oleic acid. About 99 % conversion (on the basis of oleic acid) has been achieved within 6 h at 5 % enzyme concentration. Ping-pong bi-bi mechanism (inhibition phenomenon taken into account) was applied to describe the ratios as a complex kinetic model. The kinetic parameters were determined using MATLAB language programme. The two initial rate constants KA and KB respectively were found out by different progress curves plotted with the help of MATLAB language programme. It was concluded from the results that furfuryl alcohol considerably inhibited the enzymatic reaction while oleic acid had negligible inhibitory effect. It was clearly seen that the initial rate was increased with the increase in the furfuryl alcohol concentration until 2 M/L after which there was a drop in the initial rate depicting the inhibitory effect of furfuryl alcohol. Surprisingly, it has been observed that addition of 0.1 mol of product activated the esterification reaction. Finally, the model was found to be statistically fitting well with the experimental data.

  2. Uptake of acidic and basic sugar derivatives in Lemna gibba G1

    International Nuclear Information System (INIS)

    Sanz, A.; Ullrich, C.I.

    1989-01-01

    The uptake of acidic and basic sugar derivatives in Lemna gibba L. was studied. Uronic acids applied to the experimental solution induced a small decrease of the membrane potential. After incubation of the plants in a 0.1 millimolar solution of these substrates, no decrease in the concentration of reducing groups in the external solution was detected. Respiration increased by 31% with 50 millimolar galacturonic acid, whereas no effect was found with the same concentration of glucuronic acid. Glucosamine caused a considerable concentration-dependent membrane depolarization. ( 14 C)glucosamine uptake followed Michaelis-Menten kinetics together with a linear component. Influx of this substrate was inhibited by glucose but the type of competition could not be clearly distinguished. Glucosamine, 50 millimolar, inhibited the respiration rate by 30%. The glucosamine uptake was pH-dependent, with maximum uptake at around pH 7. Lack of enhancement of uptake by low pH as well as the permanent membrane depolarization suggest a uniport mechanism for the charged species of the substrate and an electroneutral diffusion of the uncharged species

  3. Kinetics of Oxidation of Metochlopramide withChloramine-T in HClO4 Medium

    Directory of Open Access Journals (Sweden)

    K. M. Meenakshi

    2009-01-01

    Full Text Available The kinetics of oxidation of metochlopramide hydrochloride (MCP with sodium N-chloro p-toluenesulfonamide (CAT in perchloric acid solution has been studied at 313K. The reaction rate shows a first order dependence on [CAT], fractional order on [MCP] and inverse fractional order on [H+]. There is a negative effect of dielectric constant of the solvent. The addition of the reduction product of CAT has no significant effect on the rate. The rate remained unchanged with the variation in the ionic strength of the medium. The reaction fails to induce the polymerization of acrylonitrile. Thermodynamic parameters have been computed by Arrhenius plot. The stoichiometry of the reaction was found to be 1:2 and oxidation products were identified. The Michaelis-Menten type of kinetics has been proposed. CH3C6H4SO2NHCl have been assumed to be the reactive oxidizing species. Thermodynamic parameters were computed by studying reactions at different temperatures. A mechanism consistent with observed kinetics is proposed.

  4. Diatomite Modified Immobilized Delftia sp. for the Bio-Abiotic Removal of Antibiotics Amoxicillin in the Aqueous System

    Science.gov (United States)

    Gao, Lijuan; Sun, Jing; Guan, Kai; Shen, Tingting; Wang, Xikui

    2017-05-01

    Diatomite modified sodium alginate (Si/SA) immobilized Delftia sp. A2(2011) (STT01) was applied to degrade amoxicillin. The immobilized pellets provided a direct and visual probe for the degradation process due to their intrinsic bright colour. The results demonstrated that 100% of amoxicillin and 68.5% of CODcr removal were achieved after 72 h, comparing with the cases of sodium alginate (SA) system (81.2%, 46.9%) and the free cells system (60.5%, 35.5%). The degradation kinetics was in good agreement with Michaelis-Menten equation. The maximum rate (Vm ) and Michaelis constant (Km ) were calculated as 9.09 mg L-1 h-1 and 228 mg L-1, respectively. The results further revealed that diatomite not only acted as immobilization support to improve the mechanical strength and lifetime of the pellets but also as absorbent to promote the treatment efficiency. Therefore, both enzymatic catalysis and chemisorption were responsible for the removal of amoxicillin.

  5. Continuous composite riser

    Energy Technology Data Exchange (ETDEWEB)

    Slagsvold, L. [ABB Offshore Systems (Norway)

    2002-12-01

    The industry is now looking at developing reserves in waters depths of up to 3000 m (10000 ft). When moving into deeper waters the un-bonded flexible riser becomes very heavy and introduces large hang-off forces on the vessel. We are therefore investigating riser concepts incorporating new materials and with a simpler cross section that can be used for floating production. Advanced composite materials have properties such as, low weight, high strength, good durability and very good fatigue performance. Composite materials are slowly being exploited in the oil industry; they are being prototype tested for drilling risers and small diameter lines. Part of the process for the industry to accept larger diameter production risers made out of composite materials is to understand both the advantages and limitations. A new continuous composite riser system is being developed which capitalizes on the technical benefits of this material while addressing the known constraints. The fully bonded riser is being developed for ultra deep waters and its' characteristics include high temperature (160 deg C), high pressure (500 barg min), light weight, chemical resistant, good insulation, excellent fatigue characteristics and installation by reeling. The concept is based on the use of a thermoplastic liner together with a thermoplastic carbon fibre composite. This paper summarises the ongoing development, which has a goal to manufacture and qualify an 8'' riser, and includes all the steps in a production process from material qualification to the winding process and analytical modelling. (author)

  6. Continuous cell recycle fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Warren, R K; Hill, G A; MacDonald, D G

    1991-10-01

    A cell recycle fermentor using a cross-flow membrane filter has been operated for extended periods. Productivities as high as 70 g/l/h were obtained at a cell concentration of 120 g/l and a product concentration of 70 g/l. The experimental results were then fitted to previously derived biokinetic models (Warren et al., 1990) for a continuous stirred tank fermentor. A good fit for growth rate was found and the cell yield was shown to decrease with product concentration. The product yield, however, was found to remain nearly constant at all cell, substrate and product concentrations. These biokinetics, along with a previous model for the membrane filter (Warren et al., 1991) were then used in a simulalation to estimate the costs of producing ethanol in a large scale system. This simulation was optimized using a variant of the steepest descent method from which a fermentor inlet substrate concentration of 150 g/l and a net cost of $CAN 253.5/1000 L ethanol were projected. From a sensitivity analysis, the yield parameters were found to have the greatest effect on ethanol net cost of the fermentor parameters, while the operating costs and the profit was found to be most sensitive to the wheat raw material cost and to the dried grains by-product value. 55 refs., 11 tabs., 7figs.

  7. Deconstructing continuous flash suppression.

    Science.gov (United States)

    Yang, Eunice; Blake, Randolph

    2012-03-08

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.

  8. The effects of continuous venovenous hemofiltration on coagulation activation

    NARCIS (Netherlands)

    Bouman, Catherine S. C.; de Pont, Anne-Cornélie J. M.; Meijers, Joost C. M.; Bakhtiari, Kamran; Roem, Dorina; Zeerleder, Sacha; Wolbink, Gertjan; Korevaar, Johanna C.; Levi, Marcel; de Jonge, Evert

    2006-01-01

    INTRODUCTION: The mechanism of coagulation activation during continuous venovenous hemofiltration (CVVH) has not yet been elucidated. Insight into the mechanism(s) of hemostatic activation within the extracorporeal circuit could result in a more rational approach to anticoagulation. The aim of the

  9. Redefining continuing education delivery.

    Science.gov (United States)

    Carlton, K H

    1997-01-01

    individual health-care worker consumer. A number of national and world-wide trends are propelling rapid changes in the delivery modalities and types of emerging providers for health-care CE. Examples of these advanced telecommunications applications of CE opportunities for health-care personnel are becoming more prevalent in the literature and the pattern of CE marketing, and delivery evolution can be seen readily on the Internet. Continued program success and viability will belong to the individuals and organizations who are able to conceptualize and envision the positive transformations and opportunities that can occur from the evolving paradigm of education for the lifelong learner of the 21st century.

  10. Sensitivity of Deep Soil Organic Carbon Age to Sorption, Transport and Microbial Interactions - Insights from a Calibrated Process Model

    Science.gov (United States)

    Ahrens, B.; Schrumpf, M.; Reichstein, M.

    2013-12-01

    Subsoil soil organic carbon (SOC) is characterized by conventional radiocarbon ages on the order of centuries to millennia. Most vertically explicit SOC turnover models represent this persistence of deep SOC by one pool that has millennial turnover times. This approach lumps different stabilizing mechanisms such as chemical recalcitrance, sorptive stabilization and energy limitation into a single rate constant. As an alternative, we present a continuous, vertically explicit SOC decomposition model that allows for stabilization via sorption and microbial interactions (COMISSION model). We compare the COMISSION model with the SOC profile of a Haplic Podzol under a Norway spruce forest. In the COMISSION model two pools receive aboveground litter input and vertically distributed root litter input. The readily leachable and soluble fraction of litter input enters a dissolved organic carbon pool (DOC), while the rest enters the residue pool which represents polymeric, non-soluble SOC. The residue pool is depolymerized with extracellular enzymes produced by a microbial pool to enter the DOC pool which represents SOC potentially available for assimilation by microbes. The adsorption/desorption of DOC from/to mineral surfaces controls the availability of carbon in the DOC pool for assimilatory uptake by microbes. The sorption of DOC is modeled with dynamic Langmuir equations. The desorbed part of the DOC pool not only constitutes the substrate for the microbial pool, but is also transported via advection. Interactions of microbes with the residue and DOC pool are modeled with Michaelis-Menten kinetics - this not only allows representing ';priming', but also the retardation of decomposition via energy limitation in the deep soil where substrate is scarce. Further, soil organic matter is recycled within the soil profile through microbial processing - dead microbes either enter the DOC or the residue pool, and thereby also contribute to longer residence times with soil depth

  11. Fracture Mechanics

    International Nuclear Information System (INIS)

    Jang, Dong Il; Jeong, Gyeong Seop; Han, Min Gu

    1992-08-01

    This book introduces basic theory and analytical solution of fracture mechanics, linear fracture mechanics, non-linear fracture mechanics, dynamic fracture mechanics, environmental fracture and fatigue fracture, application on design fracture mechanics, application on analysis of structural safety, engineering approach method on fracture mechanics, stochastic fracture mechanics, numerical analysis code and fracture toughness test and fracture toughness data. It gives descriptions of fracture mechanics to theory and analysis from application of engineering.

  12. [Generation continuity and integration].

    Science.gov (United States)

    Zakhvatkin, Iu A

    2008-01-01

    Transformation of the cyclic morphoprocesses in Protista toward the terminal-cyclic morphoprocesses in Metazoa had lead to integration of the fomer's life circles into the latter's ontogenesis and began to supply the newly emerging ecosystems with the regular income of mortomasses. According to the palintomic hypothesis of A.A. Zakhvatkin, it was the egg that became a means of the metazoan generation continuity, and not the half set of organells acquired by descendants of a divided maternal cell in Protozoa. Origin of Metazoa and of their ontogenesis was accomplished by hypetrophic distomy and subsequent palintomic division of the protist parental cell, these processes being comparable to the ovogenesis and ovocyte division in the Metazoa. Division process in the most primitive metazoans, Leptolida and Calcarea, retained certains features of its palintomic nature that are clear in the Ctenophora, the latter though specific being most similar in this respect to the spongs and not to the Coelenterata whith whom they were united in the same phylum formerly. The ovogenesis perfection controlled by the maternal organism and leading to an increment of the nuclear-plasmic tension due to enrichment of egg with the yolk, promoted the embrionization of development and formation of the egg morphogenetic environment providing for the earlier formation processes without participation of the parental recombined genotypes. With all this, far earlier appearence of symmetry elements of definitive forms is embriogenesis along the ascending trend from the lower Metazoa to the most advanced insects. The unordered correspondence of the polarity axis of egg and the oral-aboral axis of blastula-like larva (1) is replaced by protaxony (2) in which these axes coincide, all formation processes reaching their perfection in the homoquadrant spiral division of annelids, which became a means of ovoplasma segregation. Afterward, a herequadrant division and plagioxony are developed in the course

  13. Continuous Positive Airway Pressure (CPAP)

    Science.gov (United States)

    ... ENT Doctor Near You Continuous Positive Airway Pressure (CPAP) Continuous Positive Airway Pressure (CPAP) Patient Health Information ... relations staff at newsroom@entnet.org . What Is CPAP? The most common and effective nonsurgical treatment for ...

  14. A Dynamic Continuation-Passing Style for Dynamic Delimited Continuations

    DEFF Research Database (Denmark)

    Biernacki, Dariusz; Danvy, Olivier; Millikin, Kevin Scott

    2005-01-01

    We present a new abstract machine that accounts for dynamic delimited continuations. We prove the correctness of this new abstract machine with respect to a pre-existing, definitional abstract machine. Unlike this definitional abstract machine, the new abstract machine is in defunctionalized form......, which makes it possible to state the corresponding higher-order evaluator. This evaluator is in continuation+state passing style and threads a trail of delimited continuations and a meta-continuation. Since this style accounts for dynamic delimited continuations, we refer to it as `dynamic continuation......-passing style.' We show that the new machine operates more efficiently than the definitional one and that the notion of computation induced by the corresponding evaluator takes the form of a monad. We also present new examples and a new simulation of dynamic delimited continuations in terms of static ones....

  15. Mechanical Systems, Classical Models

    CERN Document Server

    Teodorescu, Petre P

    2009-01-01

    This third volume completes the Work Mechanical Systems, Classical Models. The first two volumes dealt with particle dynamics and with discrete and continuous mechanical systems. The present volume studies analytical mechanics. Topics like Lagrangian and Hamiltonian mechanics, the Hamilton-Jacobi method, and a study of systems with separate variables are thoroughly discussed. Also included are variational principles and canonical transformations, integral invariants and exterior differential calculus, and particular attention is given to non-holonomic mechanical systems. The author explains in detail all important aspects of the science of mechanics, regarded as a natural science, and shows how they are useful in understanding important natural phenomena and solving problems of interest in applied and engineering sciences. Professor Teodorescu has spent more than fifty years as a Professor of Mechanics at the University of Bucharest and this book relies on the extensive literature on the subject as well as th...

  16. Exoplanets: The Hunt Continues!

    Science.gov (United States)

    2001-04-01

    Swiss Telescope at La Silla Very Successful Summary The intensive and exciting hunt for planets around other stars ( "exoplanets" ) is continuing with great success in both hemispheres. Today, an international team of astronomers from the Geneva Observatory and other research institutes [1] is announcing the discovery of no less than eleven new, planetary companions to solar-type stars, HD 8574, HD 28185, HD 50554, HD 74156, HD 80606, HD 82943, HD 106252, HD 141937, HD 178911B, HD 141937, among which two new multi-planet systems . The masses of these new objects range from slightly less than to about 10 times the mass of the planet Jupiter [2]. The new detections are based on measured velocity changes of the stars [3], performed with the CORALIE spectrometer on the Swiss 1.2-m Leonard Euler telescope at the ESO La Silla Observatory , as well as with instruments on telescopes at the Haute-Provence Observatory and on the Keck telescopes on Mauna Kea (Hawaii, USA). Some of the new planets are unusual: * a two-planet system (around the star HD 82943) in which one orbital period is nearly exactly twice as long as the other - cases like this (refered to as "orbital resonance") are well known in our own solar system; * another two-planet system (HD 74156), with a Jupiter-like planet and a more massive planet further out; * a planet with the most elongated orbit detected so far (HD 80606), moving between 5 and 127 million kilometers from the central star; * a giant planet moving in an orbit around its Sun-like central star that is very similar to the one of the Earth and whose potential satellites (in theory, at least) might be "habitable". At this moment, there are 63 know exoplanet candidates with minimum masses below 10 Jupiter masses, and 67 known objects with minimum masses below 17 Jupiter masses. The present team of astronomers has detected about half of these. PR Photo 13a/01 : Radial-velocity measurements of HD 82943, a two-planet system . PR Photo 13b/01 : Radial

  17. The random continued fraction transformation

    Science.gov (United States)

    Kalle, Charlene; Kempton, Tom; Verbitskiy, Evgeny

    2017-03-01

    We introduce a random dynamical system related to continued fraction expansions. It uses random combinations of the Gauss map and the Rényi (or backwards) continued fraction map. We explore the continued fraction expansions that this system produces, as well as the dynamical properties of the system.

  18. Post-reform continuation of social goals

    Energy Technology Data Exchange (ETDEWEB)

    Graniere, R.J.

    1996-01-01

    Public utility regulators are currently wrestling with the issue of how and to what extent the social goals that have grown up around traditional regulation might be continued in a restructured electric power industry. This report critically examines six mechanisms that could be used for this purpose in the wake of the introduction of competition in the generation segment. Their pros and cons are thoroughly appraised in economic terms.

  19. Layerless fabrication with continuous liquid interface production.

    Science.gov (United States)

    Janusziewicz, Rima; Tumbleston, John R; Quintanilla, Adam L; Mecham, Sue J; DeSimone, Joseph M

    2016-10-18

    Despite the increasing popularity of 3D printing, also known as additive manufacturing (AM), the technique has not developed beyond the realm of rapid prototyping. This confinement of the field can be attributed to the inherent flaws of layer-by-layer printing and, in particular, anisotropic mechanical properties that depend on print direction, visible by the staircasing surface finish effect. Continuous liquid interface production (CLIP) is an alternative approach to AM that capitalizes on the fundamental principle of oxygen-inhibited photopolymerization to generate a continual liquid interface of uncured resin between the growing part and the exposure window. This interface eliminates the necessity of an iterative layer-by-layer process, allowing for continuous production. Herein we report the advantages of continuous production, specifically the fabrication of layerless parts. These advantages enable the fabrication of large overhangs without the use of supports, reduction of the staircasing effect without compromising fabrication time, and isotropic mechanical properties. Combined, these advantages result in multiple indicators of layerless and monolithic fabrication using CLIP technology.

  20. Unexpected results from direct measurement, with a torsion microbalance in a closed system, of calcification rates of the coral Agaricia agaricites (Scleractinia:Agariicidae and concomitant changes in seawater pH

    Directory of Open Access Journals (Sweden)

    Ian M. Sandeman

    2014-09-01

    Full Text Available Ocean acidification is impacting the calcification of corals, but the mechanisms of calcification are still unclear. To explore the relationship between calcification and pH, small pieces of coral were suspended from a torsion microbalance in gently stirred, temperature controlled, seawater in a closed chamber. Net calcification rate and pH were continuously monitored while light, temperature or pH could be manipulated. The coral pieces were from the edges of thin plates of Agaricia agaricites and were studied alive and freshly collected. Unexpectedly, when calcification was taking place (n=9, 0.082 mg.hr-1.cm-2, as determined by weight increase, the pH of the surrounding seawater medium changed little (n=10, -0.0047 pH units.hr-1.cm-2. When calcification was not taking place the decrease of seawater pH was an order of magnitude higher, -0.013 pH units.hr-1.cm-2. This is the opposite of what is expected when calcium carbonate (CaCO3 forms. Similarly, fresh skeleton initially showed no change of pH in the seawater medium although the rates of weight gain were high (upto 1.0 mg hr-1.cm-2. After 10 hours, as the rate of deposition decreased following a generalized Michaelis-Menten growth curve, the pH began to decrease dramatically indicating an increase of CO2 in the seawater. These unexpected results can be explained if unstable calcium bicarbonate (Ca(HCO³2 is formed in the organic matrix/carbonic anhydrase surface and slowly transforms later to CaCO3. Pieces of living coral monitored in the chamber for 30 hours gained weight during the day and loss it at night. The loss would be consistent with the transformation of Ca(HCO³2 to CaCO3 with the release of CO2. The mean calcification rate of live coral was greater (n=8, p=0.0027 in high light (120 μmol.s-1.m-2 at 0.098 mg.hr-1.cm-2, compared to 0.063 mg.hr-1.cm-2 in low light (12 μmol.s-1.m-2. However, at the same time the mean rate of pH change was -0.0076 under low light compared to -0

  1. Continuous downstream processing of biopharmaceuticals.

    Science.gov (United States)

    Jungbauer, Alois

    2013-08-01

    Continuous manufacturing has been applied in many different industries but has been pursued reluctantly in biotechnology where the batchwise process is still the standard. A shift to continuous operation can improve productivity of a process and substantially reduce the footprint. Continuous operation also allows robust purification of labile biomolecules. A full set of unit operations is available to design continuous downstream processing of biopharmaceuticals. Chromatography, the central unit operation, is most advanced in respect to continuous operation. Here, the problem of 'batch' definition has been solved. This has also paved the way for implementation of continuous downstream processing from a regulatory viewpoint. Economic pressure, flexibility, and parametric release considerations will be the driving force to implement continuous manufacturing strategies in future. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Continuous Biometric Authentication for Authorized Aircraft Personnel: A Proposed Design

    National Research Council Canada - National Science Library

    Carrillo, Cassandra

    2003-01-01

    .... The primary goal of this thesis is to propose a hypothetical design for the use of a non- intrusive mechanism on the flight deck of an aircraft to provide continuous or periodic authentication...

  3. Collected papers on wave mechanics

    CERN Document Server

    Schrödinger, Erwin

    1929-01-01

    Quantisation as a problem of proper values ; the continuous transition from micro- to macro-mechanics ; on the relation between the quantum mechanics of Heisenberg, Born, and Jordan, and that of Schrödinger ; the Compton effect ; the energy-momentum theorem for material waves ; the exchange of energy according to wave mechanics

  4. Puzzling Mechanisms

    Science.gov (United States)

    van Deventer, M. Oskar

    2009-01-01

    The basis of a good mechanical puzzle is often a puzzling mechanism. This article will introduce some new puzzling mechanisms, like two knots that engage like gears, a chain whose links can be interchanged, and flat gears that do not come apart. It illustrates how puzzling mechanisms can be transformed into real mechanical puzzles, e.g., by…

  5. (CSTR) and 1-plug flow reactor (PFR)

    African Journals Online (AJOL)

    Administrator

    2010-12-27

    Dec 27, 2010 ... 2Department of Chemical Engineering, Obafemi Awolowo University, Ile Ife, Osun State, Nigeria. ... modeled as PFR and described by Michaelis. Menten equation. Designed equations derived from the two equations are used for the reactor sizing of ... Herbivores make a living on cellulose by possessing.

  6. DETERMINATION OF THE SPECIFIC GROWTH RATE ON ...

    African Journals Online (AJOL)

    Sewage generation is one of the dense problems Nigerians encounter on daily bases, mostly at the urbanized area where factories and industries are located. This paper is aimed at determining the specific growth rate “K” of biological activities on cassava wastewater during degradation using Michaelis-Menten Equation.

  7. Cyclodextrin-based artificial oxidases with high rate accelerations and selectivity

    DEFF Research Database (Denmark)

    Zhou, You; Lindbäck, Emil Anders; Pedersen, Christian Marcus

    2014-01-01

    Three cyclodextrin derivatives with one to four 2-O-formylmethyl groups attached to the secondary rim were prepared and investigated as catalysts for the oxidation of aminophenols in buffered dilute hydrogen peroxide. The derivatives were found to be Michaelis-Menten catalysts and to give rate ac...

  8. Signaling Cascades: Consequences of Varying Substrate and Phosphatase Levels

    DEFF Research Database (Denmark)

    Feliu, Elisenda; Knudsen, Michael; Wiuf, Carsten Henrik

    2012-01-01

    We study signaling cascades with an arbitrary number of layers of one-site phosphorylation cycles. Such cascades are abundant in nature and integrated parts of many pathways. Based on the Michaelis-Menten model of enzyme kinetics and the law of mass-action, we derive explicit analytic expressions...

  9. MODELING OF MIXED CHEMOSTAT CULTURES OF AN AEROBIC BACTERIUM, COMAMONAS-TESTOSTERONI, AND AN ANAEROBIC BACTERIUM, VEILLONELLA-ALCALESCENS - COMPARISON WITH EXPERIMENTAL-DATA

    NARCIS (Netherlands)

    GERRITSE, J; SCHUT, F; GOTTSCHAL, JC

    A mathematical model of mixed chemostat cultures of the obligately aerobic bacterium Comamonas testosteroni and the anaerobic bacterium Veillonella alcalescens grown under dual limitation Of L-lactate and oxygen was constructed. The model was based on Michaelis-Menten-type kinetics for the

  10. A Qualitative Approach to Enzyme Inhibition

    Science.gov (United States)

    Waldrop, Grover L.

    2009-01-01

    Most general biochemistry textbooks present enzyme inhibition by showing how the basic Michaelis-Menten parameters K[subscript m] and V[subscript max] are affected mathematically by a particular type of inhibitor. This approach, while mathematically rigorous, does not lend itself to understanding how inhibition patterns are used to determine the…

  11. Metabolic stereoselectivity of cytochrome P450 3A4 towards deoxypodophyllotoxin : In silico predictions and experimental validation

    NARCIS (Netherlands)

    Julsing, Mattijs K.; Vasilev, Nikolay P.; Schneidman-Duhovny, Dina; Muntendarn, Remco; Woerdenbag, Herman J.; Quax, Wim J.; Wolfson, Haim J.; Ionkova, Iliana; Kayser, Oliver

    Deoxypodophyllotoxin is stereoselectively converted into epipodophyllotoxin by recombinant human cytochrome P450 3A4 (CY-P3A4). Further kinetic analysis revealed that the Michaelis-Menten K(m) and V(max) for hydroxylation of deoxypodophyllotoxin by CYP3A4 at C7 position were 1.93 mu M and 1.48

  12. Wang and Li Afr J Tradit Complement Altern Med. (2016) 13(1):99 ...

    African Journals Online (AJOL)

    PROF ADEWUNMI

    It possesses antiseptic, anti-inflammatory, analgesic, anti-cancer and antioxidant ... All experiments on animals were conducted in accordance with and after approval by the ... With the content of gallic acid control as horizontal coordinate and the ... The kinetic constants were calculated based on Michaelis-Menten equation ...

  13. Transient competitive complexation in biological kinetic isotope fractionation explains non-steady isotopic effects: Theory and application to denitrification in soils

    Energy Technology Data Exchange (ETDEWEB)

    Maggi, F.M.; Riley, W.J.

    2009-06-01

    The theoretical formulation of biological kinetic reactions in isotopic applications often assume first-order or Michaelis-Menten-Monod kinetics under the quasi-steady-state assumption to simplify the system kinetics. However, isotopic e ects have the same order of magnitude as the potential error introduced by these simpli cations. Both formulations lead to a constant fractionation factor which may yield incorrect estimations of the isotopic effect and a misleading interpretation of the isotopic signature of a reaction. We have analyzed the isotopic signature of denitri cation in biogeochemical soil systems by Menyailo and Hungate [2006], where high {sup 15}N{sub 2}O enrichment during N{sub 2}O production and inverse isotope fractionation during N{sub 2}O consumption could not be explained with first-order kinetics and the Rayleigh equation, or with the quasi-steady-state Michaelis-Menten-Monod kinetics. When the quasi-steady-state assumption was relaxed, transient Michaelis-Menten-Monod kinetics accurately reproduced the observations and aided in interpretation of experimental isotopic signatures. These results may imply a substantial revision in using the Rayleigh equation for interpretation of isotopic signatures and in modeling biological kinetic isotope fractionation with first-order kinetics or quasi-steady-state Michaelis-Menten-Monod kinetics.

  14. New functions to estimate 305-days milk production of Gir cows : Novas Funções para Estimar a Produção de Leite, em 305 Dias de Lactação, de Vacas da Raça Gir

    NARCIS (Netherlands)

    Reboucas, G.F.; Moraes Goncalves, de T.; Martines, M.L.; Azevedo Junior, J.; Koops, W.J.

    2008-01-01

    This study aimed to calculate new accumulated and daily functions based on the Michaelis-Menten equation to estimate the 305-days production of Gir cows using test day milk yields. Data consisted of 7,412 lactation records of 3,416 Gir cows (Bos indicus) collected from 1987 to 2004 in 51 herds

  15. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    ... behaves as an effective catalyst towards oxidation of 3,5-ditertiarybutyl catechol (3,5-DTBC) in acetonitrile to its corresponding quinone derivative in air. The reaction follows first-order reaction kinetics with rate constant 4.28 × 10−5 min-1. The reaction follows Michaelis-Menten enzymatic kinetics with a turnover number of ...

  16. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    The oxidation of eleven amino acids by tetrabutylammonium tribromide (TBATB) in aqueous acetic acid results in the formation of the corresponding carbonyl compounds and ammonia. The reaction is first order with respect to TBATB. Michaelis-Menten type kinetics is observed with some of the amino acids while others ...

  17. Interactions of NH4+ and L-glutamate with NO3- transport processes of non-mycorrhizal Fagus sylvatica roots

    NARCIS (Netherlands)

    Kreuzwieser, J; Herschbach, C; Stulen, [No Value; Wiersema, P; Vaalburg, W; Rennenberg, H

    The processes of NO3- uptake and transport and the effects of NH4+ or L-glutamate on these processes were investigated with excised non-mycorrhizal beech (Fagus sylvatica L,) roots, NO3- net uptake followed uniphasic Michaelis-Menten kinetics in a concentration range of 10 mu M to 1 mM with an

  18. Purification and characterization of a chlorite dismutase from Pseudomonas chloritidismutans

    NARCIS (Netherlands)

    Mehboob, F.; Wolterink, A.F.W.M.; Vermeulen, A.J.; Jiang, B.; Hagedoorn, P.L.; Stams, A.J.M.; Kengen, S.W.M.

    2009-01-01

    The chlorite dismutase (Cld) of Pseudomonas chloritidismutans was purified from the periplasmic fraction in one step by hydroxyapatite chromatography. The enzyme has a molecular mass of 110 kDa and consists of four 31-kDa subunits. Enzyme catalysis followed Michaelis-Menten kinetics, with Vmax and

  19. Nonthermal effect of microwave irradiation on nitrite uptake in Chlamydomonas reinhardtii

    International Nuclear Information System (INIS)

    Pedrajas, C.; Cotrino, J.

    1989-01-01

    When cells of the unicellular green alga Chlamydomonas reinhardtii were subjected to microwave irradiation at 2.45 GHz, nitrite uptake kinetics still obeyed the Michaelis-Menten equation, the Km of the process remaining constant, whereas V max increased, which indicates an enhanced nonthermal permeability in irradiated cells. (author)

  20. Nitrate transport processes in Fagus-Laccaria-mycorrhizae

    NARCIS (Netherlands)

    Kreuzwieser, J; Stulen, [No Value; Wiersema, P; Vaalburg, W; Rennenberg, H

    2000-01-01

    The contribution of influx and efflux of NO3- on NO3- net uptake has been studied in excised mycorrhizae of 18-20 week old beech (Fagus sylvatica L.) trees. Net uptake rates of NO3- followed uniphasic Michaelis-Menten kinetics in the concentration range between 10 mu M and 1.0 mM external NO3-, with

  1. Immobilization of urease on copper chelated EC-Tri beads and ...

    African Journals Online (AJOL)

    Maximum reaction rate (Vmax) and Michaelis-Menten constant (km) were determined for the free and immobilized enzymes. Various characteristics of immobilized urease such as the temperature activity curve, thermal stability, operational stability and storage stability were evaluated. The results demonstrated that triazole ...

  2. Benefits of a clinical pharmacokinetic service in optimising ...

    African Journals Online (AJOL)

    before the termination of the study (test period). Patients kept a seizure diary throughout the study. The MichaelisMenten model was used to calculate doses and predict steady-state serum concentrations. Setting. ine epilepsy clinics. Subjects. One hundred and ninety-five (113 black and 82 coloured) compliant people with ...

  3. Cyclodextrin Aldehydes are Oxidase Mimics

    DEFF Research Database (Denmark)

    Fenger, Thomas Hauch; Bjerre, Jeannette; Bols, Mikael

    2009-01-01

    Cyclodextrins containing 6-aldehyde groups were found to catalyse oxidation of aminophenols in the presence of hydrogen peroxide. The catalysis followed Michaelis-Menten kinetics and is related to the catalysis previously observed with cyclodextrin ketones. A range of different cyclodextrin aldeh...

  4. International Meeting on Cholinesterases (5th) Held in Madras, India on 24-28 September, 1994.

    Science.gov (United States)

    1994-09-01

    found that hydrolysis of thioesters deviated from simple Michaelis-Menten model. Kinetics was triphasic , displaying complexities of both BuChE and ACHE...of recombinant human acetylcholinesterase (rHuAChE) produced by human embryonic kidney cell line (293) in a fixed-bed reactor (1) was investigated at

  5. Asymptotic behaviour near extinction of continuous-state branching processes

    OpenAIRE

    Berzunza, Gabriel; Pardo, Juan Carlos

    2016-01-01

    In this note, we study the asymptotic behaviour near extinction of (sub-) critical continuous state branching processes. In particular, we establish an analogue of Khintchin's law of the iterated logarithm near extinction time for a continuous state branching process whose branching mechanism satisfies a given condition and its reflected process at its infimum.

  6. Continuous Non-malleable Codes

    DEFF Research Database (Denmark)

    Faust, Sebastian; Mukherjee, Pratyay; Nielsen, Jesper Buus

    2014-01-01

    or modify it to the encoding of a completely unrelated value. This paper introduces an extension of the standard non-malleability security notion - so-called continuous non-malleability - where we allow the adversary to tamper continuously with an encoding. This is in contrast to the standard notion of non...... is necessary to achieve continuous non-malleability in the split-state model. Moreover, we illustrate that none of the existing constructions satisfies our uniqueness property and hence is not secure in the continuous setting. We construct a split-state code satisfying continuous non-malleability. Our scheme...... is based on the inner product function, collision-resistant hashing and non-interactive zero-knowledge proofs of knowledge and requires an untamperable common reference string. We apply continuous non-malleable codes to protect arbitrary cryptographic primitives against tampering attacks. Previous...

  7. Sibling bereavement and continuing bonds.

    Science.gov (United States)

    Packman, Wendy; Horsley, Heidi; Davies, Betty; Kramer, Robin

    2006-11-01

    Historically, from a Freudian and medical model perspective, emotional disengagement from the deceased was seen as essential to the successful adaptation of bereavement. A major shift in the bereavement literature has occurred and it is now generally accepted that despite the permanence of physical separation, the bereaved remains involved and connected to the deceased and can be emotionally sustained through continuing bonds. The majority of literature has focused on adults and on the nature of continuing bonds following the death of a spouse. In this article, the authors demonstrate how the continuing bonds concept applies to the sibling relationship. We describe the unique continued relationship formed by bereaved children and adolescents following a sibling loss, highlight the factors that influence the siblings continuing bonds expressions, and offer clinical interventions. In our view, mental health professionals can play an important role in helping parents encourage activities that may facilitate the creation and maintenance of continuing bonds in their children.

  8. The Continued Assessment of Self-Continuity and Identity

    Science.gov (United States)

    Dunkel, Curtis S.; Minor, Leslie; Babineau, Maureen

    2010-01-01

    Studies have found that self-continuity is predictive of a substantial number of important outcome variables. However, a recent series of studies brings into question the traditional method of measuring self-continuity in favor of an alternative (B. M. Baird, K. Le, & R. E. Lucas, 2006). The present study represents a further comparison of…

  9. Beyond Continuous Delivery: An Empirical Investigation of Continuous Deployment Challenges

    DEFF Research Database (Denmark)

    Shahin, Mojtaba; Ali Babar, Muhammad; Zahedi, Mansooreh

    2017-01-01

    Context: A growing number of software organizations have been adopting Continuous DElivery (CDE) and Continuous Deployment (CD) practices. Researchers have started investing significant efforts in studying different aspects of CDE and CD. Many studies refer to CDE (i.e., where an application is p...

  10. Continuous exponential martingales and BMO

    CERN Document Server

    Kazamaki, Norihiko

    1994-01-01

    In three chapters on Exponential Martingales, BMO-martingales, and Exponential of BMO, this book explains in detail the beautiful properties of continuous exponential martingales that play an essential role in various questions concerning the absolute continuity of probability laws of stochastic processes. The second and principal aim is to provide a full report on the exciting results on BMO in the theory of exponential martingales. The reader is assumed to be familiar with the general theory of continuous martingales.

  11. Continuous acoustic emission from aluminium

    International Nuclear Information System (INIS)

    Fenici, P.; Kiesewetter, N.; Schiller, P.

    1976-01-01

    Continuous acoustic emission of aluminum single crystals and polycrystals during tensile tests at constant cross-head speed and at room temperature is measured with a Root Mean Square Level recorder. By means of the Kaiser effect it is shown that the continuous emission is related to the plastic deformation. The plot of continuous emission against strain takes different shapes for pure single crystals, pure polycrystals and impure polycrystals. The measured voltages have about the same value for pure single and polycrystals and are considerably greater than that for impure polycrystals. A method is developed to distinguish between continuous emission and burst

  12. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1968-01-01

    The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3......The B field configuration of a Q-device has been modified into a magnetic Laval nozzle. Continuous supersonic plasma flow is observed with M≈3...

  13. Perspectives: The Continuous Improvement Trap

    Science.gov (United States)

    Arnold, David L.

    2011-01-01

    Accrediting agencies, legislators, pundits, and even higher educational professionals have become enamored with applying the language of continuous improvement to learning outcomes. The Southern Association of Colleges and Schools Commission on Colleges specifically uses the term "continuing improvement" in Core Standard 2.5, one of its…

  14. Continual integral in perturbation theory

    International Nuclear Information System (INIS)

    Slavnov, A.A.

    1975-01-01

    It is shown that all results obtained by means of continual integration within the framework of perturbation theory are completely equivalent to those obtained by the usual diagram technique and are therfore just as rigorous. A rigorous justification is given for the rules for operating with continual integrals in perturbation theory. (author)

  15. Quantum mechanics

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    The book is on quantum mechanics. The emphasis is on the basic concepts and the methodology. The chapters include: Breakdown of classical concepts; Quantum mechanical concepts; Basic postulates of quantum mechanics; solution of problems in quantum mechanics; Simple harmonic oscillator; and Angular Momentum

  16. Applications of a fast, continuous wavelet transform

    Energy Technology Data Exchange (ETDEWEB)

    Dress, W.B.

    1997-02-01

    A fast, continuous, wavelet transform, based on Shannon`s sampling theorem in frequency space, has been developed for use with continuous mother wavelets and sampled data sets. The method differs from the usual discrete-wavelet approach and the continuous-wavelet transform in that, here, the wavelet is sampled in the frequency domain. Since Shannon`s sampling theorem lets us view the Fourier transform of the data set as a continuous function in frequency space, the continuous nature of the functions is kept up to the point of sampling the scale-translation lattice, so the scale-translation grid used to represent the wavelet transform is independent of the time- domain sampling of the signal under analysis. Computational cost and nonorthogonality aside, the inherent flexibility and shift invariance of the frequency-space wavelets has advantages. The method has been applied to forensic audio reconstruction speaker recognition/identification, and the detection of micromotions of heavy vehicles associated with ballistocardiac impulses originating from occupants` heart beats. Audio reconstruction is aided by selection of desired regions in the 2-D representation of the magnitude of the transformed signal. The inverse transform is applied to ridges and selected regions to reconstruct areas of interest, unencumbered by noise interference lying outside these regions. To separate micromotions imparted to a mass-spring system (e.g., a vehicle) by an occupants beating heart from gross mechanical motions due to wind and traffic vibrations, a continuous frequency-space wavelet, modeled on the frequency content of a canonical ballistocardiogram, was used to analyze time series taken from geophone measurements of vehicle micromotions. By using a family of mother wavelets, such as a set of Gaussian derivatives of various orders, features such as the glottal closing rate and word and phrase segmentation may be extracted from voice data.

  17. Continuum mechanics

    CERN Document Server

    Spencer, A J M

    2004-01-01

    The mechanics of fluids and the mechanics of solids represent the two major areas of physics and applied mathematics that meet in continuum mechanics, a field that forms the foundation of civil and mechanical engineering. This unified approach to the teaching of fluid and solid mechanics focuses on the general mechanical principles that apply to all materials. Students who have familiarized themselves with the basic principles can go on to specialize in any of the different branches of continuum mechanics. This text opens with introductory chapters on matrix algebra, vectors and Cartesian ten

  18. Nonextensive formalism and continuous Hamiltonian systems

    International Nuclear Information System (INIS)

    Boon, Jean Pierre; Lutsko, James F.

    2011-01-01

    A recurring question in nonequilibrium statistical mechanics is what deviation from standard statistical mechanics gives rise to non-Boltzmann behavior and to nonlinear response, which amounts to identifying the emergence of 'statistics from dynamics' in systems out of equilibrium. Among several possible analytical developments which have been proposed, the idea of nonextensive statistics introduced by Tsallis about 20 years ago was to develop a statistical mechanical theory for systems out of equilibrium where the Boltzmann distribution no longer holds, and to generalize the Boltzmann entropy by a more general function S q while maintaining the formalism of thermodynamics. From a phenomenological viewpoint, nonextensive statistics appeared to be of interest because maximization of the generalized entropy S q yields the q-exponential distribution which has been successfully used to describe distributions observed in a large class of phenomena, in particular power law distributions for q>1. Here we re-examine the validity of the nonextensive formalism for continuous Hamiltonian systems. In particular we consider the q-ideal gas, a model system of quasi-particles where the effect of the interactions are included in the particle properties. On the basis of exact results for the q-ideal gas, we find that the theory is restricted to the range q<1, which raises the question of its formal validity range for continuous Hamiltonian systems.

  19. Quantum mechanics and umbral calculus

    International Nuclear Information System (INIS)

    Lopez-Sendino, J E; Negro, J; Olmo, M A del; Salgado, E

    2008-01-01

    In this paper we present the first steps for obtaining a discrete Quantum Mechanics making use of the Umbral Calculus. The idea is to discretize the continuous Schroedinger equation substituting the continuous derivatives by discrete ones and the space-time continuous variables by well determined operators that verify some Umbral Calculus conditions. In this way we assure that some properties of integrability and symmetries of the continuous equation are preserved and also the solutions of the continuous case can be recovered discretized in a simple way. The case of the Schroedinger equation with a potential depending only in the space variable is discussed.

  20. Ferroelectric domain continuity over grain boundaries

    DEFF Research Database (Denmark)

    Mantri, Sukriti; Oddershede, Jette; Damjanovic, Dragan

    2017-01-01

    Formation and mobility of domain walls in ferroelectric materials is responsible for many of their electrical and mechanical properties. Domain wall continuity across grain boundaries has been observed since the 1950's and is speculated to affect the grain boundary-domain interactions, thereby...... impacting macroscopic ferroelectric properties in polycrystalline systems. However detailed studies of such correlated domain structures across grain boundaries are limited. In this work, we have developed the mathematical requirements for domain wall plane matching at grain boundaries of any given...... orientation. We have also incorporated the effect of grain boundary ferroelectric polarization charge created when any two domains meet at the grain boundary plane. The probability of domain wall continuity for three specific grain misorientations is studied. Use of this knowledge to optimize processing...

  1. Protein design using continuous rotamers.

    Directory of Open Access Journals (Sweden)

    Pablo Gainza

    2012-01-01

    Full Text Available Optimizing amino acid conformation and identity is a central problem in computational protein design. Protein design algorithms must allow realistic protein flexibility to occur during this optimization, or they may fail to find the best sequence with the lowest energy. Most design algorithms implement side-chain flexibility by allowing the side chains to move between a small set of discrete, low-energy states, which we call rigid rotamers. In this work we show that allowing continuous side-chain flexibility (which we call continuous rotamers greatly improves protein flexibility modeling. We present a large-scale study that compares the sequences and best energy conformations in 69 protein-core redesigns using a rigid-rotamer model versus a continuous-rotamer model. We show that in nearly all of our redesigns the sequence found by the continuous-rotamer model is different and has a lower energy than the one found by the rigid-rotamer model. Moreover, the sequences found by the continuous-rotamer model are more similar to the native sequences. We then show that the seemingly easy solution of sampling more rigid rotamers within the continuous region is not a practical alternative to a continuous-rotamer model: at computationally feasible resolutions, using more rigid rotamers was never better than a continuous-rotamer model and almost always resulted in higher energies. Finally, we present a new protein design algorithm based on the dead-end elimination (DEE algorithm, which we call iMinDEE, that makes the use of continuous rotamers feasible in larger systems. iMinDEE guarantees finding the optimal answer while pruning the search space with close to the same efficiency of DEE.Software is available under the Lesser GNU Public License v3. Contact the authors for source code.

  2. Interactive Development of Community Education and Migrant Workers’ Continuing Education

    Institute of Scientific and Technical Information of China (English)

    Ning; WANG

    2015-01-01

    Community education is an essential carrier of continuing education and plays a positive role in promoting continuing education of migrant workers. On the one hand,it can raise employment quality and labor skills of migrant workers; on the other hand,it manifests function of serving society of community education. Besides,it is also an important measure for building learning society and lifelong learning system.From the perspective of interactive development,it discusses interactive relationship between community education and migrant workers’ continuing education,analyzes their interactive mechanism,and comes up with recommendations for developing community education and migrant workers’ continuing education.

  3. Manipulating continuous variable photonic entanglement

    International Nuclear Information System (INIS)

    Plenio, M.B.

    2005-01-01

    I will review our work on photonic entanglement in the continuous variable regime including both Gaussian and non-Gaussian states. The feasibility and efficiency of various entanglement purification protocols are discussed this context. (author)

  4. Continuing education and professional development

    International Nuclear Information System (INIS)

    Adams, Edwina

    2002-01-01

    The success of a profession will be determined upon its education and training. A profession is required to encompass: a core body of knowledge; a set of ethical codes of practice; and have practitioners with humanistic qualities. In order to maintain the success of a profession it is necessary to have continuing education, which enhances professional development. Continuing professional education includes a form of self-regulation, which ensures the maintenance of a minimum standard of practice in this ever-changing workplace, and by regulating this standard, the discipline becomes more accountable to the client and the profession as a whole. In Australia, the Nuclear Medicine society's continuing education programs and Universities offering postgraduate programs promote continuing education. If technologists are to successfully keep up with developments in instrumentation, protocols and changing health care requirements, we must ensure that the education of practitioners does not cease at certification of entry to the workplace (Au)

  5. Rapid Continuous Multimaterial Extrusion Bioprinting

    NARCIS (Netherlands)

    Liu, Wanjun; Zhang, Yu Shrike; Heinrich, Marcel A.; De Ferrari, F; Jang, HL; Bakht, SM; Alvarez, MM; Yang, J; Li, YC; Trujillo-de Stantiago, G; Miri, AK; Zhu, K; Khoshakhlagh, P; Prakash, G; Cheng, H; Guan, X; Zhong, Z; Ju, J; Zhu, GH; Jin, X; Ryon Shin, Su; Dokmeci, M.R.; Khademhosseini, Ali

    The development of a multimaterial extrusion bioprinting platform is reported. This platform is capable of depositing multiple coded bioinks in a continuous manner with fast and smooth switching among different reservoirs for rapid fabrication of complex constructs, through digitally controlled

  6. Continuation of superpave projects monitoring.

    Science.gov (United States)

    2011-07-01

    This study involved the continuous monitoring of material properties and field performance of twelve Superpave project sections in Florida for the establishment of reasonable and effective mixture design guidelines and criteria, the identification an...

  7. Continuous Delivery and Quality Monitoring

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    After introducing Continuous Delivery, I will switch the topic and try to answer the question how much should we invest in quality and how to do it efficiently. My observations reveal that software quality is often considered as the slo...

  8. Stratigraphy -- The Fall of Continuity.

    Science.gov (United States)

    Byers, Charles W.

    1982-01-01

    Reviews advances in stratigraphy as illustrated in the current geological literature, discussing discontinuity and how the recognition of discontinuity in the stratigraphic record is changing views of Superposition and Original Lateral Continuity. (Author/JN)

  9. Qubit Complexity of Continuous Problems

    National Research Council Canada - National Science Library

    Papageorgiou, A; Traub, J. F

    2005-01-01

    .... The authors show how to obtain the classical query complexity for continuous problems. They then establish a simple formula for a lower bound on the qubit complexity in terms of the classical query complexity...

  10. Competitive Strategy in Continuing Education.

    Science.gov (United States)

    Baden, Clifford

    1987-01-01

    Reviews strategic variables available to those planning continuing education marketing programs. Discusses generic competitive strategies: (1) overall cost leadership, (2) differentiation, and (3) specialization. Mentions several potential problems. (CH)

  11. Novel device for creating continuous curvilinear capsulorhexis.

    Science.gov (United States)

    Soylak, Mustafa

    2016-01-01

    The purpose of this paper is to develop a novel capsulorhexis system. Mechatronics Laboratory, University of Erciyes and Kayseri Maya Eye Hospital. A 3D model was created and simulations were conducted to develop a new device which was designed, fabricated and tested for continuous curvilinear capsulorhexis (CCC). The name of this system is the electro-mechanical capsulorhexis system (EMCS). The 3D model was created by using a commercial design software and a 3D printer was used to fabricate the EMCS Finite element analysis and geometrical relation tests of the EMCS for different sized lenses were performed. The results show that the EMCS is a perfect solution for capsulorhexis surgeries, without mechanical or geometrical problems. The EMCS can open the anterior lens capsule more easily and effectively than manual CCC applications and needs less experience.

  12. Continuous-Energy Data Checks

    Energy Technology Data Exchange (ETDEWEB)

    Haeck, Wim [Radioprotection and Nuclear Safety Institute, Fontenay-aux-Roses (France); Conlin, Jeremy Lloyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); McCartney, Austin Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parsons, Donald Kent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-25

    The purpose of this report is to provide an overview of all Quality Assurance tests that have to be performed on a nuclear data set to be transformed into an ACE formatted nuclear data file. The ACE file is capable of containing different types of data such as continuous energy neutron data, thermal scattering data, etc. Within this report, we will limit ourselves to continuous energy neutron data.

  13. Atypical work and employment continuity

    OpenAIRE

    Addison, John T.; Surfield, Christopher J.

    2009-01-01

    Atypical employment arrangements such as agency temporary work and contracting have long been criticized as offering more precarious and unstable work than regular employment. Using data from two datasets – the CAEAS and the NLSY79 – we determine whether workers who take such jobs rather than regular employment, or the alternative of continued job search, subsequently experience greater or lesser employment continuity. Observed differences between the various working arrangements are starkest...

  14. Continuous Disintegrations of Gaussian Processes

    OpenAIRE

    LaGatta, Tom

    2010-01-01

    The goal of this paper is to understand the conditional law of a stochastic process once it has been observed over an interval. To make this precise, we introduce the notion of a continuous disintegration: a regular conditional probability measure which varies continuously in the conditioned parameter. The conditioning is infinite-dimensional in character, which leads us to consider the general case of probability measures in Banach spaces. Our main result is that for a certain quantity $M$ b...

  15. Mechanical Ventilation

    Science.gov (United States)

    ... ventilation is a life support treatment. A mechanical ventilator is a machine that helps people breathe when ... to breathe enough on their own. The mechanical ventilator is also called a ventilator , respirator, or breathing ...

  16. Mechanical design

    CERN Document Server

    Risitano, Antonino

    2011-01-01

    METHODOLOGICAL STATEMENT OF ENGINEERING DESIGNApproaches to product design and developmentMechanical design and environmental requirementsPROPERTIES OF ENGINEERING MATERIALSMaterials for mechanical designCharacterization of metalsStress conditionsFatigue of materialsOptimum material selection in mechanical designDESIGN OF MECHANICAL COMPONENTS AND SYSTEMSFailure theoriesHertz theoryLubrificationShafts and bearingsSplines and keysSpringsFlexible machine elementsSpur gearsPress and shrink fitsPressure tubesCouplingsClutchesBrakes

  17. NLC Mechanical

    Science.gov (United States)

    text only Mechanical Systems.gif (14697 bytes) NLC Home Page NLC Technical SLAC Permanent Magnets Organization Overview The Mechanical Systems Group Organization is shown on the NLC Project Group Organization Chart (Next Linear Collider Technical Web Page). The Mechanical Systems Group operates on a matrixed

  18. Mechanical Kinesiology.

    Science.gov (United States)

    Barham, Jerry N.

    Mechanical kinesiology is defined as a study of the mechanical factors affecting human movement, i.e., applying the physical laws of mechanics to the study of human motor behavior. This textbook on the subject is divided into thirty lessons. Each lesson is organized into three parts: a part on the text proper; a part entitled "study…

  19. Mechanisms Design

    DEFF Research Database (Denmark)

    Restrepo-Giraldo, John Dairo

    2006-01-01

    Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design such mechan......Most products and machines involve some kind of controlled movement. From window casements to DVD players, from harbor cranes to the shears to prune your garden, all these machines require mechanisms to move. This course intends to provide the analytical and conceptual tools to design...... using criteria such as size, performance parameters, operation environment, etc. Content: Understanding Mechanisms Design (2 weeks) Definitions, mechanisms representations, kinematic diagrams, the four bar linkage, mobility, applications of mechanisms, types of mechanisms, special mechanisms, the design......: equations for various mechanisms. At the end of this module you will be able to analyze existing mechanisms and to describe their movement. Designing mechanisms (7 weeks) Type synthesis and dimensional synthesis, function generation, path generation, three precision points in multi-loop mechanisms...

  20. Business continuity 2014: From traditional to integrated Business Continuity Management.

    Science.gov (United States)

    Ee, Henry

    As global change continues to generate new challenges and potential threats to businesses, traditional business continuity management (BCM) slowly reveals its limitations and weak points to ensuring 'business resiliency' today. Consequently, BCM professionals also face the challenge of re-evaluating traditional concepts and introducing new strategies and industry best practices. This paper points to why traditional BCM is no longer sufficient in terms of enabling businesses to survive in today's high-risk environment. It also looks into some of the misconceptions about BCM and other stumbling blocks to establishing effective BCM today. Most importantly, however, this paper provides tips based on the Business Continuity Institute's (BCI) Good Practices Guideline (GPG) and the latest international BCM standard ISO 22301 on how to overcome the issues and challenges presented.

  1. Discrete mechanics

    CERN Document Server

    Caltagirone, Jean-Paul

    2014-01-01

    This book presents the fundamental principles of mechanics to re-establish the equations of Discrete Mechanics. It introduces physics and thermodynamics associated to the physical modeling.  The development and the complementarity of sciences lead to review today the old concepts that were the basis for the development of continuum mechanics. The differential geometry is used to review the conservation laws of mechanics. For instance, this formalism requires a different location of vector and scalar quantities in space. The equations of Discrete Mechanics form a system of equations where the H

  2. Discrete mechanics

    International Nuclear Information System (INIS)

    Lee, T.D.

    1985-01-01

    This paper reviews the role of time throughout all phases of mechanics: classical mechanics, non-relativistic quantum mechanics, and relativistic quantum theory. As an example of the relativistic quantum field theory, the case of a massless scalar field interacting with an arbitrary external current is discussed. The comparison between the new discrete theory and the usual continuum formalism is presented. An example is given of a two-dimensional random lattice and its duel. The author notes that there is no evidence that the discrete mechanics is more appropriate than the usual continuum mechanics

  3. Continuous carbon nanotube reinforced composites.

    Science.gov (United States)

    Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M

    2008-09-01

    Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

  4. Mechanically Invisible Polymer Coatings

    DEFF Research Database (Denmark)

    2014-01-01

    phase comprises particles, said particles comprising a filler material and an encapsulating coating of a second polymeric material, wherein the backbones of the first and second polymeric materials are the same. The composition may be used in electroactive polymers (EAPs) in order to obtain mechanically......The present invention relates to a composition comprising encapsulated particles in a polymeric material. The composition comprises a continuous phase and a discontinuous phase incorporated therein, wherein the continuous phase comprises a first polymeric material and wherein the discontinuous...... invisible polymer coatings....

  5. Entanglement-continuous unitary transformations

    Energy Technology Data Exchange (ETDEWEB)

    Sahin, Serkan; Orus, Roman [Institute of Physics, Johannes Gutenberg University, 55099 Mainz (Germany)

    2016-07-01

    In this talk we present a new algorithm for quantum many-body systems using continuous unitary transformations (CUT) and tensor networks (TNs). With TNs we are able to approximate the solution to the flow equations that lie at the heart of continuous unitary transformations. We call this method Entanglement-Continuous Unitary Transformations (eCUT). It allows us to compute expectation values of local observables as well as tensor network representations of ground states and low-energy excited states. An implementation of the method is shown for 1d systems using matrix product operators. We show preliminary results for the 1d transverse-field Ising model to demonstrate the feasibility of the method.

  6. Continuous fractional distillation of petroleum

    Energy Technology Data Exchange (ETDEWEB)

    1921-11-05

    This invention has for its object a process of distillation, fractional, and continuous, of shale oil, tar, etc., characterized by the vapors leaving the evaporation chamber being forced, before condensation, to go over a continuous circuit. The vapors traverse first a preheater then return to the vaporization chamber in which they are passed along large surfaces and by application of the counter-current principle in contact with the liquid to be distilled. They stream through the chamber in a continuous manner (the quantity of vapor emitted in the circuit being determined in a manner to advance the distillation just to completion); the excess of vapor formed being removed from the circuit and sent to a condensing apparatus for fractionation.

  7. Baseline budgeting for continuous improvement.

    Science.gov (United States)

    Kilty, G L

    1999-05-01

    This article is designed to introduce the techniques used to convert traditionally maintained department budgets to baseline budgets. This entails identifying key activities, evaluating for value-added, and implementing continuous improvement opportunities. Baseline Budgeting for Continuous Improvement was created as a result of a newly named company president's request to implement zero-based budgeting. The president was frustrated with the mind-set of the organization, namely, "Next year's budget should be 10 to 15 percent more than this year's spending." Zero-based budgeting was not the answer, but combining the principles of activity-based costing and the Just-in-Time philosophy of eliminating waste and continuous improvement did provide a solution to the problem.

  8. Distributed synthesis in continuous time

    DEFF Research Database (Denmark)

    Hermanns, Holger; Krčál, Jan; Vester, Steen

    2016-01-01

    We introduce a formalism modelling communication of distributed agents strictly in continuous-time. Within this framework, we study the problem of synthesising local strategies for individual agents such that a specified set of goal states is reached, or reached with at least a given probability....... The flow of time is modelled explicitly based on continuous-time randomness, with two natural implications: First, the non-determinism stemming from interleaving disappears. Second, when we restrict to a subclass of non-urgent models, the quantitative value problem for two players can be solved in EXPTIME....... Indeed, the explicit continuous time enables players to communicate their states by delaying synchronisation (which is unrestricted for non-urgent models). In general, the problems are undecidable already for two players in the quantitative case and three players in the qualitative case. The qualitative...

  9. Continuous biodisel productions: A review

    Directory of Open Access Journals (Sweden)

    Stamenković Ivica S.

    2009-01-01

    Full Text Available Continuous biodiesel production on laboratory and industrial scale was analyzed, with focus on their advantages and disadvantages. Attention was paid to specific characteristics of industrial processes in order to point out the advanced technologies. The well-known base-catalyzed continuous biodiesel production processes are related to problems caused by the immiscibility of the reactants (alcohol and oil, application of relatively high operating temperature (usually the boiling temperature of alcohol or one near it and obtained yield of methyl ester yields lower than desired. One way to overcome these problems is to employ special reactor design favoring the emulsion process and increasing the overall rate of biodiesel production process, even at room temperature and atmospheric pressure. The second way is to apply heterogeneous catalysts in continuous processes, which will probably be the optimal approach to economically justified and environmentally friendly biodiesel production.

  10. Applied mechanics of solids

    CERN Document Server

    Bower, Allan F

    2009-01-01

    Modern computer simulations make stress analysis easy. As they continue to replace classical mathematical methods of analysis, these software programs require users to have a solid understanding of the fundamental principles on which they are based. Develop Intuitive Ability to Identify and Avoid Physically Meaningless Predictions Applied Mechanics of Solids is a powerful tool for understanding how to take advantage of these revolutionary computer advances in the field of solid mechanics. Beginning with a description of the physical and mathematical laws that govern deformation in solids, the text presents modern constitutive equations, as well as analytical and computational methods of stress analysis and fracture mechanics. It also addresses the nonlinear theory of deformable rods, membranes, plates, and shells, and solutions to important boundary and initial value problems in solid mechanics. The author uses the step-by-step manner of a blackboard lecture to explain problem solving methods, often providing...

  11. Rough case-based reasoning system for continues casting

    Science.gov (United States)

    Su, Wenbin; Lei, Zhufeng

    2018-04-01

    The continuous casting occupies a pivotal position in the iron and steel industry. The rough set theory and the CBR (case based reasoning, CBR) were combined in the research and implementation for the quality assurance of continuous casting billet to improve the efficiency and accuracy in determining the processing parameters. According to the continuous casting case, the object-oriented method was applied to express the continuous casting cases. The weights of the attributes were calculated by the algorithm which was based on the rough set theory and the retrieval mechanism for the continuous casting cases was designed. Some cases were adopted to test the retrieval mechanism, by analyzing the results, the law of the influence of the retrieval attributes on determining the processing parameters was revealed. A comprehensive evaluation model was established by using the attribute recognition theory. According to the features of the defects, different methods were adopted to describe the quality condition of the continuous casting billet. By using the system, the knowledge was not only inherited but also applied to adjust the processing parameters through the case based reasoning method as to assure the quality of the continuous casting and improve the intelligent level of the continuous casting.

  12. Continuous-variable quantum games

    International Nuclear Information System (INIS)

    Li Hui; Du Jiangfeng; Massar, Serge

    2002-01-01

    We investigate the quantization of games in which the players can access to a continuous set of classical strategies, making use of continuous-variable quantum systems. For the particular case of the Cournot's duopoly, we find that, even though the two players both act as 'selfishly' in the quantum game as they do in the classical game, they are found to virtually cooperate due to the quantum entanglement between them. We also find that the original Einstein-Podolksy-Rosen state contributes to the best profits that the two firms could ever attain. Moreover, we propose a practical experimental setup for the implementation of such quantum games

  13. Continuous lengths of oxide superconductors

    Science.gov (United States)

    Kroeger, Donald M.; List, III, Frederick A.

    2000-01-01

    A layered oxide superconductor prepared by depositing a superconductor precursor powder on a continuous length of a first substrate ribbon. A continuous length of a second substrate ribbon is overlaid on the first substrate ribbon. Sufficient pressure is applied to form a bound layered superconductor precursor powder between the first substrate ribbon and the second substrate ribbon. The layered superconductor precursor is then heat treated to establish the oxide superconducting phase. The layered oxide superconductor has a smooth interface between the substrate and the oxide superconductor.

  14. Continuous production of polymethylpentene membranes

    Science.gov (United States)

    Epperson, B.J.; Burnett, L.J.; Helm, V.D.

    1983-11-15

    Gas separation membranes may be prepared in a continuous manner by passing a porous support which may, if so desired, be backed by a fabric through a solution of polymethylpentene dissolved in an organic solvent such as hexane. The support member is passed through the solution while one side thereof is in contact with a roller, thereby permitting only one side of the support member to be coated with the polymer. After continuously withdrawing the support member from the bath, the solvent is allowed to evaporate and the resulting membrane is recovered.

  15. LANL continuity of operations plan

    Energy Technology Data Exchange (ETDEWEB)

    Senutovitch, Diane M [Los Alamos National Laboratory

    2010-12-22

    The Los Alamos National Laboratory (LANL) is a premier national security research institution, delivering scientific and engineering solutions for the nation's most crucial and complex problems. Our primary responsibility is to ensure the safety, security, and reliability of the nation's nuclear stockpile. LANL emphasizes worker safety, effective operational safeguards and security, and environmental stewardship, outstanding science remains the foundation of work at the Laboratory. In addition to supporting the Laboratory's core national security mission, our work advances bioscience, chemistry, computer science, earth and environmental sciences, materials science, and physics disciplines. To accomplish LANL's mission, we must ensure that the Laboratory EFs continue to be performed during a continuity event, including localized acts of nature, accidents, technological or attack-related emergencies, and pandemic or epidemic events. The LANL Continuity of Operations (COOP) Plan documents the overall LANL COOP Program and provides the operational framework to implement continuity policies, requirements, and responsibilities at LANL, as required by DOE 0 150.1, Continuity Programs, May 2008. LANL must maintain its ability to perform the nation's PMEFs, which are: (1) maintain the safety and security of nuclear materials in the DOE Complex at fixed sites and in transit; (2) respond to a nuclear incident, both domestically and internationally, caused by terrorist activity, natural disaster, or accident, including mobilizing the resources to support these efforts; and (3) support the nation's energy infrastructure. This plan supports Continuity of Operations for Los Alamos National Laboratory (LANL). This plan issues LANL policy as directed by the DOE 0 150.1, Continuity Programs, and provides direction for the orderly continuation of LANL EFs for 30 days of closure or 60 days for a pandemic/epidemic event. Initiation of COOP operations may

  16. Continuous Natural Fiber Reinforced Thermoplastic Composites by Fiber Surface Modification

    Directory of Open Access Journals (Sweden)

    Patcharat Wongsriraksa

    2013-01-01

    Full Text Available Continuous natural fiber reinforced thermoplastic materials are expected to replace inorganic fiber reinforced thermosetting materials. However, in the process of fabricating the composite, it is difficult to impregnate the thermoplastic resin into reinforcement fiber because of the high melt viscosity. Therefore, intermediate material, which allows high impregnation during molding, has been investigated for fabricating continuous fiber reinforced thermoplastic composite by aligning resin fiber alongside reinforcing fiber with braiding technique. This intermediate material has been called “microbraid yarn (MBY.” Moreover, it is well known that the interfacial properties between natural fiber and resin are low; therefore, surface treatment on continuous natural fiber was performed by using polyurethane (PU and flexible epoxy (FLEX to improve the interfacial properties. The effect of surface treatment on the mechanical properties of continuous natural fiber reinforced thermoplastic composites was examined. From these results, it was suggested that surface treatment by PU with low content could produce composites with better mechanical properties.

  17. Mechanical drawing

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Ho Seon; Lee, Geun Hui

    2004-04-15

    This book deals with how to read and draw the mechanical drawing, which includes the basic of drawing like purpose, kinds, and criterion, projection, special projection drawing, omission of the figure, section, and types of section, dimensioning method, writing way of allowable limit size, tolerance of regular size, parts list and assembling drawing, fitting, mechanical elements like screw, key, pin, rivet, spring, bearing, pipe, valve, welding, geometric tolerance and mechanical materials.

  18. Classical mechanics

    CERN Document Server

    Benacquista, Matthew J

    2018-01-01

    This textbook provides an introduction to classical mechanics at a level intermediate between the typical undergraduate and advanced graduate level. This text describes the background and tools for use in the fields of modern physics, such as quantum mechanics, astrophysics, particle physics, and relativity. Students who have had basic undergraduate classical mechanics or who have a good understanding of the mathematical methods of physics will benefit from this book.

  19. Mechanical science

    CERN Document Server

    Bolton, W C

    2013-01-01

    This book gives comprehensive coverage of mechanical science for HNC/HND students taking mechanical engineering courses, including all topics likely to be covered in both years of such courses, as well as for first year undergraduate courses in mechanical engineering. It features 500 problems with answers and 200 worked examples. The third edition includes a new section on power transmission and an appendix on mathematics to help students with the basic notation of calculus and solution of differential equations.

  20. Coordination in continuously repeated games

    NARCIS (Netherlands)

    Weeren, A.J.T.M.; Schumacher, J.M.; Engwerda, J.C.

    1995-01-01

    In this paper we propose a model to describe the effectiveness of coordination in a continuously repeated two-player game. We study how the choice of a decision rule by a coordinator affects the strategic behavior of the players, resulting in more or less cooperation. Our model requires the analysis

  1. Teamwork, Leadership, and Continuous Improvement

    NARCIS (Netherlands)

    Keijser, Wouter Alexander; Glaudemans, Andor; Medema, Jitze; Dierckx, Rudi; Ahaus, Kees

    2017-01-01

    In this chapter, we describe the enhanced TeamSTEPPS® curriculum as fundament to creating a “culture of continuous improvement” in nuclear medicine. This evidence-based and modular teamwork system is deployed in concordance with a novel medical leadership development program. It provides a

  2. For Time-Continuous Optimisation

    DEFF Research Database (Denmark)

    Heinrich, Mary Katherine; Ayres, Phil

    2016-01-01

    Strategies for optimisation in design normatively assume an artefact end-point, disallowing continuous architecture that engages living systems, dynamic behaviour, and complex systems. In our Flora Robotica investigations of symbiotic plant-robot bio-hybrids, we re- quire computational tools...

  3. Geodesic continued fractions and LLL

    NARCIS (Netherlands)

    Beukers, F

    2014-01-01

    We discuss a proposal for a continued fraction-like algorithm to determine simultaneous rational approximations to dd real numbers α1,…,αdα1,…,αd. It combines an algorithm of Hermite and Lagarias with ideas from LLL-reduction. We dynamically LLL-reduce a quadratic form with parameter tt as t↓0t↓0.

  4. Continuity and Change in Appalachia.

    Science.gov (United States)

    Shinn, Larry D.

    1999-01-01

    Appalachian continuities include attachment to land and religion, high teen pregnancy, and low literacy and income. Trends in Appalachia that institutions of higher education must address are higher rates of college attendance, migration to urban areas, changes in student learning styles, and increasing pressure to educate students to workplace…

  5. Continuous supersonic plasma wind tunnel

    DEFF Research Database (Denmark)

    Andersen, S.A.; Jensen, Vagn Orla; Nielsen, P.

    1969-01-01

    The normal magnetic field configuration of a Q device has been modified to obtain a 'magnetic Laval nozzle'. Continuous supersonic plasma 'winds' are obtained with Mach numbers ~3. The magnetic nozzle appears well suited for the study of the interaction of supersonic plasma 'winds' with either...

  6. Comprehensive geriatric assessment | Lipschitz | Continuing ...

    African Journals Online (AJOL)

    Continuing Medical Education. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 25, No 9 (2007) > ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

  7. Administrative Computing in Continuing Education.

    Science.gov (United States)

    Broxton, Harry

    1982-01-01

    Describes computer applications in the Division of Continuing Education at Brigham Young University. These include instructional applications (computer assisted instruction, computer science education, and student problem solving) and administrative applications (registration, payment records, grades, reports, test scoring, mailing, and others).…

  8. In the interest of continuity

    CERN Multimedia

    Association du personnel

    2009-01-01

    Every five years a new Management takes over the fifth floor of the Main Building. The arrival of a new Director-General comes with a desire to change the managerial style. Whilst not contesting the current need for this, we would like to remind you that continuity in the Organization is ensured by the personnel and its Staff Association representatives.

  9. Pythagorean Approximations and Continued Fractions

    Science.gov (United States)

    Peralta, Javier

    2008-01-01

    In this article, we will show that the Pythagorean approximations of [the square root of] 2 coincide with those achieved in the 16th century by means of continued fractions. Assuming this fact and the known relation that connects the Fibonacci sequence with the golden section, we shall establish a procedure to obtain sequences of rational numbers…

  10. Workload Control with Continuous Release

    NARCIS (Netherlands)

    Phan, B. S. Nguyen; Land, M. J.; Gaalman, G. J. C.

    2009-01-01

    Workload Control (WLC) is a production planning and control concept which is suitable for the needs of make-to-order job shops. Release decisions based on the workload norms form the core of the concept. This paper develops continuous time WLC release variants and investigates their due date

  11. Continuum Mechanics

    CERN Document Server

    Romano, Antonio

    2010-01-01

    This book offers a broad overview of the potential of continuum mechanics to describe a wide range of macroscopic phenomena in real-world problems. Building on the fundamentals presented in the authors' previous book, Continuum Mechanics using Mathematica(R), this new work explores interesting models of continuum mechanics, with an emphasis on exploring the flexibility of their applications in a wide variety of fields.Specific topics, which have been chosen to show the power of continuum mechanics to characterize the experimental behavior of real phenomena, include: * various aspects of nonlin

  12. Excursions in fluvial (dis)continuity

    Science.gov (United States)

    Grant, Gordon E.; O'Connor, James E.; Safran, Elizabeth

    2017-01-01

    : punctuated episodes of cutting and filling, discretization of landscapes into hierarchies of structure and control, the work of extreme events. Orderly and progressive evolution towards a steady or ideal state is replaced by chaotic episodes of disturbance and recovery. Recent developments in the field of geomorphology suggest that we may be on the cusp of a new paradigm that recognizes that both continuous and discontinuous processes and mechanisms play a role in fluvial processes and landscape evolution with neither holding sway over the other and both needed to see rivers as they are.

  13. Hot Ductility Behavior of a Peritectic Steel during Continuous Casting

    OpenAIRE

    Arıkan, Mustafa

    2015-01-01

    Hot ductility properties of a peritectic steel for welded gas cylinders during continuous casting were studied by performing hot tensile tests at certain temperatures ranging from 1200 to 700 °C for some cooling rates by using Gleeble-3500 thermo-mechanical test and simulation machine in this study. The effects of cooling rate and strain rate on hot ductility were investigated and continuous casting process map (time-temperature-ductility) were plotted for this material. Reduction of area ...

  14. Spacetime replication of continuous variable quantum information

    International Nuclear Information System (INIS)

    Hayden, Patrick; Nezami, Sepehr; Salton, Grant; Sanders, Barry C

    2016-01-01

    The theory of relativity requires that no information travel faster than light, whereas the unitarity of quantum mechanics ensures that quantum information cannot be cloned. These conditions provide the basic constraints that appear in information replication tasks, which formalize aspects of the behavior of information in relativistic quantum mechanics. In this article, we provide continuous variable (CV) strategies for spacetime quantum information replication that are directly amenable to optical or mechanical implementation. We use a new class of homologically constructed CV quantum error correcting codes to provide efficient solutions for the general case of information replication. As compared to schemes encoding qubits, our CV solution requires half as many shares per encoded system. We also provide an optimized five-mode strategy for replicating quantum information in a particular configuration of four spacetime regions designed not to be reducible to previously performed experiments. For this optimized strategy, we provide detailed encoding and decoding procedures using standard optical apparatus and calculate the recovery fidelity when finite squeezing is used. As such we provide a scheme for experimentally realizing quantum information replication using quantum optics. (paper)

  15. Hydrodynamic chronoamperometry for probing kinetics of anaerobic microbial metabolism - case study of Faecalibacterium prausnitzii

    Science.gov (United States)

    Prévoteau, Antonin; Geirnaert, Annelies; Arends, Jan B. A.; Lannebère, Sylvain; van de Wiele, Tom; Rabaey, Korneel

    2015-07-01

    Monitoring in vitro the metabolic activity of microorganisms aids bioprocesses and enables better understanding of microbial metabolism. Redox mediators can be used for this purpose via different electrochemical techniques that are either complex or only provide non-continuous data. Hydrodynamic chronoamperometry using a rotating disc electrode (RDE) can alleviate these issues but was seldom used and is poorly characterized. The kinetics of Faecalibacterium prausnitzii A2-165, a beneficial gut microbe, were determined using a RDE with riboflavin as redox probe. This butyrate producer anaerobically ferments glucose and reduces riboflavin whose continuous monitoring on a RDE provided highly accurate kinetic measurements of its metabolism, even at low cell densities. The metabolic reaction rate increased linearly over a broad range of cell concentrations (9 × 104 to 5 × 107 cells.mL-1). Apparent Michaelis-Menten kinetics was observed with respect to riboflavin (KM = 6 μM kcat = 5.3×105 s-1, at 37 °C) and glucose (KM = 6 μM kcat = 2.4 × 105 s-1). The short temporal resolution allows continuous monitoring of fast cellular events such as kinetics inhibition with butyrate. Furthermore, we detected for the first time riboflavin reduction by another potential probiotic, Butyricicoccus pullicaecorum. The ability of the RDE for fast, accurate, simple and continuous measurements makes it an ad hoc tool for assessing bioprocesses at high resolution.

  16. Mechanisms for generating froissaron

    International Nuclear Information System (INIS)

    Glushko, N.I.; Kobylinski, N.A.; Martynov, E.S.; Shelest, V.P.

    1982-01-01

    From a common point of view, we consider the mechanisms for generating froissaron which arise due to the quasieikonal approximation, the U-matrix approach and the method of continued unitarity. A realistic model for the input pomeron is suggested and the data on high-energy pp-scattering are described. Likeness and difference of asymptotic and preasymptotic regimes for three variants of froissaron are discussed

  17. Automotive Mechanics.

    Science.gov (United States)

    Linder, Ralph C.; And Others

    This curriculum guide, which was validated by vocational teachers and mechanics in the field, describes the competencies needed by entry-level automotive mechanics. This guide lists 15 competencies; for each competency, various tasks with their performance objective, student learning experiences, suggested instructional techniques, instructional…

  18. Respiratory mechanics

    CERN Document Server

    Wilson, Theodore A

    2016-01-01

    This book thoroughly covers each subfield of respiratory mechanics: pulmonary mechanics, the respiratory pump, and flow. It presents the current understanding of the field and serves as a guide to the scientific literature from the golden age of respiratory mechanics, 1960 - 2010. Specific topics covered include the contributions of surface tension and tissue forces to lung recoil, the gravitational deformation of the lung, and the interdependence forces that act on pulmonary airways and blood vessels. The geometry and kinematics of the ribs is also covered in detail, as well as the respiratory action of the external and internal intercostal muscles, the mechanics of the diaphragm, and the quantitative compartmental models of the chest wall is also described. Additionally, flow in the airways is covered thoroughly, including the wave-speed and viscous expiratory flow-limiting mechanisms; convection, diffusion and the stationary front; and the distribution of ventilation. This is an ideal book for respiratory ...

  19. College mechanics

    CERN Document Server

    Şengül, Caner

    2016-01-01

    College Mechanics QueBank has been designed to be different, enthusiastic, interesting and helpful to you. Therefore, it is not just a test bank about mechanics but also it is like a compass in order to find your way in mechanics Each chapter in this book is put in an order to follow a hierarchy of the mechanics topics; from vectors to simple harmonic motion. Throughout the book there are many multiple choice and long answer questions for you to solve. They have been created for YGS, LYS, SAT, IB or other standardized exams in the world because mechanics has no boundaries and so Physics has no country. Learn the main principle of each chapter and explore the daily life applications. Then you can start to solve the questions by planning a problem solving method carefully. Finally, enjoy solving the questions and discover the meachanics of the universe once more.

  20. Fracture Mechanics

    CERN Document Server

    Zehnder, Alan T

    2012-01-01

    Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

  1. A continuous wave RF vacuum window

    International Nuclear Information System (INIS)

    Walton, R.

    1999-09-01

    An essential part of an ICRF system to be used in fusion reactor is the RF window. This is fitted in a coaxial transmission line. It forms a vacuum and tritium boundary between the antenna, situated inside the machine, and the transmission line, which feeds it. A double window is required with a vacuum inter-space. The dielectric, which forms the vacuum boundary, must be brazed into its housing. The window must be of a robust construction, and capable of withstanding both axial and radial loads. The vacuum boundaries should be thick walled in order act as a suitable tritium barrier. A further requirement is that the window is capable of continuous operation. The design of such a window is presented below. A half scale prototype has been manufactured, which has successfully completed RF, vacuum, and mechanical testing at JET, but has no water cooling, which is a requirement for continuous operation. The design presented here is for a window to match the existing 30 Ω main transmission lines at JET. It employs two opposed ceramic dielectric cones with a much increased angle of incidence compared with existing JET windows. The housing is machined from titanium. Small corona rings are used, and the tracking distance along the ceramic surface is large. The geometry minimizes the peak electric field strength. The design uses substantial pre-stressing during manufacture, to produce a compressive stress field throughout the dielectric material. Significant tensile stresses in the ceramic, and therefore the possibility of fracture due to applied thermal and mechanical loading, are eliminated in this way. A full-scale actively cooled RF window using this basic design should be capable of continuous use at 50 kV in the 20 - 90 MHz range. A half scale, inertially cooled prototype window has been designed, built and tested successfully at JET to 48 kV for up to 20 seconds. The prototype uses alumina for the dielectric, whereas beryllia is more appropriate for continuous

  2. A graphical user interface for a method to infer kinetics and network architecture (MIKANA).

    Science.gov (United States)

    Mourão, Márcio A; Srividhya, Jeyaraman; McSharry, Patrick E; Crampin, Edmund J; Schnell, Santiago

    2011-01-01

    One of the main challenges in the biomedical sciences is the determination of reaction mechanisms that constitute a biochemical pathway. During the last decades, advances have been made in building complex diagrams showing the static interactions of proteins. The challenge for systems biologists is to build realistic models of the dynamical behavior of reactants, intermediates and products. For this purpose, several methods have been recently proposed to deduce the reaction mechanisms or to estimate the kinetic parameters of the elementary reactions that constitute the pathway. One such method is MIKANA: Method to Infer Kinetics And Network Architecture. MIKANA is a computational method to infer both reaction mechanisms and estimate the kinetic parameters of biochemical pathways from time course data. To make it available to the scientific community, we developed a Graphical User Interface (GUI) for MIKANA. Among other features, the GUI validates and processes an input time course data, displays the inferred reactions, generates the differential equations for the chemical species in the pathway and plots the prediction curves on top of the input time course data. We also added a new feature to MIKANA that allows the user to exclude a priori known reactions from the inferred mechanism. This addition improves the performance of the method. In this article, we illustrate the GUI for MIKANA with three examples: an irreversible Michaelis-Menten reaction mechanism; the interaction map of chemical species of the muscle glycolytic pathway; and the glycolytic pathway of Lactococcus lactis. We also describe the code and methods in sufficient detail to allow researchers to further develop the code or reproduce the experiments described. The code for MIKANA is open source, free for academic and non-academic use and is available for download (Information S1).

  3. Continuous hydrino thermal power system

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Randell L.; Zhao, Guibing; Good, William [BlackLight Power, Inc., 493 Old Trenton Road, Cranbury, NJ 08512 (United States)

    2011-03-15

    The specifics of a continuous hydrino reaction system design are presented. Heat from the hydrino reactions within individual cells provide both reactor power and the heat for regeneration of the reactants. These processes occur continuously and the power from each cell is constant. The conversion of thermal power to electrical power requires the use of a heat engine exploiting a cycle such as a Rankine, Brayton, Stirling, or steam-engine cycle. Due to the temperatures, economy goal, and efficiency, the Rankine cycle is the most practical and can produce electricity at 30-40% efficiency with a component capital cost of about $300 per kW electric. Conservatively, assuming a conversion efficiency of 25% the total cost with the addition of the boiler and chemical components is estimated at $1064 per kW electric. (author)

  4. Continuous-Variable Entanglement Swapping

    Directory of Open Access Journals (Sweden)

    Kevin Marshall

    2015-05-01

    Full Text Available We present a very brief overview of entanglement swapping as it relates to continuous-variable quantum information. The technical background required is discussed and the natural link to quantum teleportation is established before discussing the nature of Gaussian entanglement swapping. The limitations of Gaussian swapping are introduced, along with the general applications of swapping in the context of to quantum communication and entanglement distribution. In light of this, we briefly summarize a collection of entanglement swapping schemes which incorporate a non-Gaussian ingredient and the benefits of such schemes are noted. Finally, we motivate the need to further study and develop such schemes by highlighting requirements of a continuous-variable repeater.

  5. Continuous hydrino thermal power system

    International Nuclear Information System (INIS)

    Mills, Randell L.; Zhao, Guibing; Good, William

    2011-01-01

    The specifics of a continuous hydrino reaction system design are presented. Heat from the hydrino reactions within individual cells provide both reactor power and the heat for regeneration of the reactants. These processes occur continuously and the power from each cell is constant. The conversion of thermal power to electrical power requires the use of a heat engine exploiting a cycle such as a Rankine, Brayton, Stirling, or steam-engine cycle. Due to the temperatures, economy goal, and efficiency, the Rankine cycle is the most practical and can produce electricity at 30-40% efficiency with a component capital cost of about $300 per kW electric. Conservatively, assuming a conversion efficiency of 25% the total cost with the addition of the boiler and chemical components is estimated at $1064 per kW electric.

  6. Analytic continuation in perturbative QCD

    International Nuclear Information System (INIS)

    Caprini, Irinel

    2002-01-01

    We discuss some attempts to improve standard perturbative expansion in QCD by using the analytic continuation in the momentum and the Borel complex planes. We first analyse the momentum-plane analyticity properties of the Borel-summed Green functions in perturbative QCD and the connection between the Landau singularities and the infrared renormalons. By using the analytic continuation in the Borel complex plane, we propose a new perturbative series replacing the standard expansion in powers of the normalized coupling constant a. The new expansion functions have branch point and essential singularities at the origin of the complex a-plane and divergent Taylor expansions in powers of a. On the other hand the modified expansion of the QCD correlators is convergent under rather conservative conditions. (author)

  7. PIPER Continuous Adiabatic Demagnetization Refrigerator

    Science.gov (United States)

    Kimball, Mark O.; Shirron, Peter J.; Canavan, Edgar R.; James, Bryan L.; Sampson, Michael A.; Letmate, Richard V.

    2017-01-01

    We report upon the development and testing of a 4-stage adiabatic demagnetization refrigerator (ADR) capable of continuous cooling at 0.100 Kelvin. This cooler is being built to cool the detector array aboard NASA's Primordial Inflation Polarization Explorer (PIPER) observatory. The goal of this balloon mission is to measure the primordial gravitational waves that should exist if the theory of cosmological inflation is correct. At altitude, the ADR will hold the array of transition-edge sensors at 100 mK continuously while periodically rejecting heat to a 1.2 K pumped helium bath. During testing on ground, the array is held at the same temperature but heat is rejected to a 4.2 K helium bath indicating the flexibility in this coolers design.

  8. Nasal continuous positive airway pressure

    DEFF Research Database (Denmark)

    Scholze, Alexandra; Lamwers, Stephanie; Tepel, Martin

    2012-01-01

    Obstructive sleep apnoea (OSA) is linked to increased cardiovascular risk. This risk can be reduced by nasal continuous positive airway pressure (nCPAP) treatment. As OSA is associated with an increase of several vasoconstrictive factors, we investigated whether nCPAP influences the digital volume...... pulse wave. We performed digital photoplethysmography during sleep at night in 94 consecutive patients who underwent polysomnography and 29 patients treated with nCPAP. Digital volume pulse waves were obtained independently of an investigator and were quantified using an algorithm for continuous.......01; n = 94) and the arousal index (Spearman correlation, r = 0.21; p CPAP treatment, the AHI was significantly reduced from 27 ± 3 events · h(-1) to 4 ± 2 events · h(-1) (each n = 29; p

  9. Personal continuous route pattern mining

    Institute of Scientific and Technical Information of China (English)

    Qian YE; Ling CHEN; Gen-cai CHEN

    2009-01-01

    In the daily life, people often repeat regular routes in certain periods. In this paper, a mining system is developed to find the continuous route patterns of personal past trips. In order to count the diversity of personal moving status, the mining system employs the adaptive GPS data recording and five data filters to guarantee the clean trips data. The mining system uses a client/server architecture to protect personal privacy and to reduce the computational load. The server conducts the main mining procedure but with insufficient information to recover real personal routes. In order to improve the scalability of sequential pattern mining, a novel pattern mining algorithm, continuous route pattern mining (CRPM), is proposed. This algorithm can tolerate the different disturbances in real routes and extract the frequent patterns. Experimental results based on nine persons' trips show that CRPM can extract more than two times longer route patterns than the traditional route pattern mining algorithms.

  10. Continuous lactation in dairy cows

    DEFF Research Database (Denmark)

    Madsen, Torben Gosvig; Nielsen, Mette Benedicte Olaf; Andersen, Jens Bech

    2008-01-01

    Reports over the past decade have indicated that normal lactational performance can be achieved in genetically superior and high-producing dairy cows, even when the dry period between 2 lactations is omitted. The hypothesis tested in this experiment was that normal lactogenesis I and metabolic...... function may be achievable in continuously milked high-yielding dairy cows as a result of the genetic selection for lactation performance and hence longevity of mammary epithelial cells. The milk production and mammary nutrient uptake in response to omission of the dry period for cows with an expected peak...... milk yield higher than 45 kg/d were studied in 28 Holstein dairy cows managed without bovine somatotropin. Performance and metabolic parameters were followed in late gestation and in the following early lactation. Fourteen cows were milked continuously throughout late gestation, and another 14 dairy...

  11. Black holes by analytic continuation

    CERN Document Server

    Amati, Daniele

    1997-01-01

    In the context of a two-dimensional exactly solvable model, the dynamics of quantum black holes is obtained by analytically continuing the description of the regime where no black hole is formed. The resulting spectrum of outgoing radiation departs from the one predicted by the Hawking model in the region where the outgoing modes arise from the horizon with Planck-order frequencies. This occurs early in the evaporation process, and the resulting physical picture is unconventional. The theory predicts that black holes will only radiate out an energy of Planck mass order, stabilizing after a transitory period. The continuation from a regime without black hole formation --accessible in the 1+1 gravity theory considered-- is implicit in an S matrix approach and provides in this way a possible solution to the problem of information loss.

  12. Continuous monitoring of gaseous effluents

    International Nuclear Information System (INIS)

    Velasco, A.; Giraut, H.; Prado, M.; Bonino, A.D.

    1990-01-01

    The system allows to continuously determine the radioactive materials discharge (iodine, noble gases and aerosols) to the environment. It consists in compelling, by a pump, a known and fixed fraction of the total flow and preserving the aerosols by a filter. The gas -now free from aerosols- traverses an activated carbon filter which keeps the iodine; after being free from aerosols and iodine, the effluent traverses a measurement chambers for noble gases which has a scintillator. (Author) [es

  13. Developing a Continuous Improvement System

    Science.gov (United States)

    2016-09-16

    disagree that continuous improvement is critical to an organization’s suc-cess, since conducting business using a status quo philosophy will not work...for implementing one of these processes include: better operational efficiency, increased customer satisfaction, improved employee morale ...when a problem in reliability or maintenance may become the greatest opportunity. As described in the January-February 2011 issue of Defense AT&L

  14. Zeolites with continuously tuneable porosity

    OpenAIRE

    Wheatley, Paul S; Chlubná-Eliášová, Pavla; Greer, Heather; Zhou, Wuzong; Seymour, Valerie R; Dawson, Daniel M; Ashbrook, Sharon E; Pinar, Ana B; McCusker, Lynne B; Opanasenko, Maksym; Cejka, Jiří; Morris, Russell E

    2014-01-01

    Czech Science Foundation. Grant Number: P106/12/G015 Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneabl...

  15. Continuous alcoholic fermentation of molasses

    Energy Technology Data Exchange (ETDEWEB)

    Kazimierz, J

    1962-01-01

    The first Polish plant for ontinuous alcohol fermentation of molasses is described. Continuous fermentation permits a better use of the installation, automatic control, and shorter fermentation time. It yields more CO/sub 2/ for dry ice manufacture and decreases corrosion of apparatus. From 22 to 24% mash is used, giving a yield of 61.1 of 100-proof alc./kg. sucrose and an average of 37 kg. of dry yeast/1000 l. alcohol

  16. Manioc alcohol by continuous fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Del Bianco, V; de Queiroz Araujo, N; Miceli, A; Souza e Silva, P C; da Silva Burle, J A

    1976-01-01

    EtOH was produced from dry cassava meal by first obtaining a glucose syrup by enzymic action, then fermenting the syrup with yeast. Bacillus subtilis amylase and Aspergillus awamori amyloglucosidase were prepared by growing the organisms on cassava meal. Both enzymes were used to saccharify the cassava starch to syrup. Saccharomyces cervisiae ATCC 1133 was then used in a continuous process to produce EtOH.

  17. Correlates of oral contraception continuation.

    Science.gov (United States)

    Ewer, P A; Gibbs, J O

    1971-05-01

    A sample of 139 predominantly black, young, low-income patients who had accepted oral contraception at a publicly supported family planning clinic has been analyzed for correlates of oral contraception continuation. Interviews were conducted 10-12 months after the clinic visit; at this time 38% of the patients continued taking oral contraceptives. It was found that patients with the highest continuation rates were 18-24 years old, in the 2-3 parity group, living with their husbands, had low-parity mothers, and were able to fill prescriptions in less time with more convenient methods of transportation. Discontinuers tended to have high-parity mothers, live with parents or head their own households, and to be in the 13-17 or 25-45 year old age groups. Fear of long-term use of oral contraceptives and perceived side effects appeared to be implicated in discontinuation. The rate of discontinuation may be associated with irregular coital experience and less consistent exposure to pregnancy.

  18. Topological Photonics for Continuous Media

    Science.gov (United States)

    Silveirinha, Mario

    Photonic crystals have revolutionized light-based technologies during the last three decades. Notably, it was recently discovered that the light propagation in photonic crystals may depend on some topological characteristics determined by the manner how the light states are mutually entangled. The usual topological classification of photonic crystals explores the fact that these structures are periodic. The periodicity is essential to ensure that the underlying wave vector space is a closed surface with no boundary. In this talk, we prove that it is possible calculate Chern invariants for a wide class of continuous bianisotropic electromagnetic media with no intrinsic periodicity. The nontrivial topology of the relevant continuous materials is linked with the emergence of edge states. Moreover, we will demonstrate that continuous photonic media with the time-reversal symmetry can be topologically characterized by a Z2 integer. This novel classification extends for the first time the theory of electronic topological insulators to a wide range of photonic platforms, and is expected to have an impact in the design of novel photonic systems that enable a topologically protected transport of optical energy. This work is supported in part by Fundacao para a Ciencia e a Tecnologia Grant Number PTDC/EEI-TEL/4543/2014.

  19. Quantum mechanics

    CERN Document Server

    Powell, John L

    2015-01-01

    Suitable for advanced undergraduates, this thorough text focuses on the role of symmetry operations and the essentially algebraic structure of quantum-mechanical theory. Based on courses in quantum mechanics taught by the authors, the treatment provides numerous problems that require applications of theory and serve to supplement the textual material.Starting with a historical introduction to the origins of quantum theory, the book advances to discussions of the foundations of wave mechanics, wave packets and the uncertainty principle, and an examination of the Schrödinger equation that includ

  20. Quantum mechanics

    International Nuclear Information System (INIS)

    Rae, A.I.M.

    1981-01-01

    This book, based on a thirty lecture course given to students at the beginning of their second year, covers the quantum mechanics required by physics undergraduates. Early chapters deal with wave mechanics, including a discussion of the energy states of the hydrogen atom. These are followed by a more formal development of the theory, leading to a discussion of some advanced applications and an introduction to the conceptual problems associated with quantum measurement theory. Emphasis is placed on the fundamentals of quantum mechanics. Problems are included at the end of each chapter. (U.K.)

  1. Indexing mechanisms

    International Nuclear Information System (INIS)

    Wood, A.G.; Parker, G.E.; Berry, R.

    1976-01-01

    It is stated that the indexing mechanism described can be used in a nuclear reactor fuel element inspection rig. It comprises a tubular body adapted to house a canister containing a number of fuel elements located longtitudinally, and has two chucks spaced apart for displacing the fuel elements longitudinally in a stepwise manner, together with a plunger mechanism for displacing them successively into the chucks. A measuring unit is located between the chucks for measuring the diameter of the fuel elements at intervals about their circumferences, and a secondary indexing mechanism is provided for rotating the measuring unit in a stepwise manner. (U.K.)

  2. Robot Mechanisms

    CERN Document Server

    Lenarcic, Jadran; Stanišić, Michael M

    2013-01-01

    This book provides a comprehensive introduction to the area of robot mechanisms, primarily considering industrial manipulators and humanoid arms. The book is intended for both teaching and self-study. Emphasis is given to the fundamentals of kinematic analysis and the design of robot mechanisms. The coverage of topics is untypical. The focus is on robot kinematics. The book creates a balance between theoretical and practical aspects in the development and application of robot mechanisms, and includes the latest achievements and trends in robot science and technology.

  3. Measuring coating thicknesses on continuously moving material

    International Nuclear Information System (INIS)

    Holler, J.H.; Stanton, W.B.; Spongr, J.J.; Joffe, B.B.; Raffelsberger, P.W.; Tiebor, J.E.

    1982-01-01

    A method and apparatus using radiation techniques for measuring coating thicknesses on continuously moving strip material without altering a predetermined path along which it travels. A shuttle carrying a measuring probe having a radioactive isotope source and a detection device is provided for reciprocation along a preselected segment of the path of the strip. The shuttle and the probe are releasably engaged with the strip and carried thereby for synchronous movement therewith in the forward direction during a measurement cycle, and are disengaged from the strip when no measurement is being made, the movement of the shuttle then being controlled by an independent drive mechanism, shown as a belt drive, which reciprocates the shuttle along the rails. A belt drives it forward more slowly than the strip, which then engages the shuttle to pull it at strip speed, allowed by a pulley clutch. (author)

  4. Large lepton mixings from continuous symmetries

    International Nuclear Information System (INIS)

    Everett, Lisa; Ramond, Pierre

    2007-01-01

    Within the broad context of quark-lepton unification, we investigate the implications of broken continuous family symmetries which result from requiring that in the limit of exact symmetry, the Dirac mass matrices yield hierarchical masses for the quarks and charged leptons, but lead to degenerate light neutrino masses as a consequence of the seesaw mechanism, without requiring hierarchical right-handed neutrino mass terms. Quark mixing is then naturally small and proportional to the size of the perturbation, but lepton mixing is large as a result of degenerate perturbation theory, shifted from maximal mixing by the size of the perturbation. Within this approach, we study an illustrative two-family prototype model with an SO(2) family symmetry, and discuss extensions to three-family models

  5. Dissipative Continuous Spontaneous Localization (CSL) model.

    Science.gov (United States)

    Smirne, Andrea; Bassi, Angelo

    2015-08-05

    Collapse models explain the absence of quantum superpositions at the macroscopic scale, while giving practically the same predictions as quantum mechanics for microscopic systems. The Continuous Spontaneous Localization (CSL) model is the most refined and studied among collapse models. A well-known problem of this model, and of similar ones, is the steady and unlimited increase of the energy induced by the collapse noise. Here we present the dissipative version of the CSL model, which guarantees a finite energy during the entire system's evolution, thus making a crucial step toward a realistic energy-conserving collapse model. This is achieved by introducing a non-linear stochastic modification of the Schrödinger equation, which represents the action of a dissipative finite-temperature collapse noise. The possibility to introduce dissipation within collapse models in a consistent way will have relevant impact on the experimental investigations of the CSL model, and therefore also on the testability of the quantum superposition principle.

  6. Is Fitts' law continuous in discrete aiming?

    Directory of Open Access Journals (Sweden)

    Rita Sleimen-Malkoun

    Full Text Available The lawful continuous linear relation between movement time and task difficulty (i.e., index of difficulty; ID in a goal-directed rapid aiming task (Fitts' law has been recently challenged in reciprocal performance. Specifically, a discontinuity was observed at critical ID and was attributed to a transition between two distinct dynamic regimes that occurs with increasing difficulty. In the present paper, we show that such a discontinuity is also present in discrete aiming when ID is manipulated via target width (experiment 1 but not via target distance (experiment 2. Fitts' law's discontinuity appears, therefore, to be a suitable indicator of the underlying functional adaptations of the neuro-muscular-skeletal system to task properties/requirements, independently of reciprocal or discrete nature of the task. These findings open new perspectives to the study of dynamic regimes involved in discrete aiming and sensori-motor mechanisms underlying the speed-accuracy trade-off.

  7. CYP2E1 Metabolism of Styrene Involves Allostery

    Science.gov (United States)

    Hartman, Jessica H.; Boysen, Gunnar

    2012-01-01

    We are the first to report allosterism during styrene oxidation by recombinant CYP2E1 and human liver microsomes. At low styrene concentrations, oxidation is inefficient because of weak binding to CYP2E1 (Ks = 830 μM). A second styrene molecule then binds CYP2E1 with higher affinity (Kss = 110 μM) and significantly improves oxidation to achieve a kcat of 6.3 nmol · min−1 · nmol CYP2E1−1. The transition between these metabolic cycles coincides with reported styrene concentrations in blood from exposed workers; thus, this CYP2E1 mechanism may be relevant in vivo. Scaled modeling of the in vitro-positive allosteric mechanism for styrene metabolism to its in vivo clearance led to significant deviations from the traditional model based on Michaelis-Menten kinetics. Low styrene levels were notably much less toxic than generally assumed. We interrogated the allosteric mechanism using the CYP2E1-specific inhibitor and drug 4-methylpyrazole, which we have shown binds two CYP2E1 sites. From the current studies, styrene was a positive allosteric effector on 4-methylpyrazole binding, based on a 10-fold increase in 4-methylpyrazole binding affinity from Ki 0.51 to Ksi 0.043 μM. The inhibitor was a negative allosteric effector on styrene oxidation, because kcat decreased 6-fold to 0.98 nmol · min−1 · nmol CYP2E1−1. Consequently, mixtures of styrene and other molecules can induce allosteric effects on binding and metabolism by CYP2E1 and thus mitigate the efficiency of their metabolism and corresponding effects on human health. Taken together, our elucidation of mechanisms for these allosteric reactions provides a powerful tool for further investigating the complexities of CYP2E1 metabolism of drugs and pollutants. PMID:22807108

  8. Continuous Emission of A Radiation Quantum

    International Nuclear Information System (INIS)

    Zheng-Johansson, J X

    2013-01-01

    It is in accordance with such experiments as single photon self-interference that a photon, conveying one radiation energy quantum h × frequency , is spatially extensive and stretches an electromagnetic wave train. A wave train, hence an energy quantum, can only be emitted (or absorbed) by its source (or absorber) gradually. In both two processes the wave and ''particle'' attributes of the radiation field are simultaneously prominent, where an overall satisfactory theory has been lacking; for the latter process no known theoretical description currently exists. This paper presents a first principles treatment, in a unified framework of the classical and quantum mechanics, of the latter process, the emission (similarly absorption) of a single radiation quantum based on the dynamics of the radiation-emitting source, a charged oscillator, which is itself extensive across the potential well in which it oscillates. During the emission of one single radiation quantum, the extensive charged oscillator undergoes a continuous radiation damping and is non-stationary. This process is in this work treated using a quasi stationary approach, whereby the classical equation of motion, which directly facilitates the correspondence principle for a particle oscillator, and the quantum wave equation are established for each sufficiently brief time interval. As an inevitable consequence of the division of the total time for emitting one single quantum, a fractional Planck constant h is introduced. The solutions to the two simultaneous equations yield for the charged oscillator a continuously exponentially decaying Hamiltonian that is at the same time quantised with respect to the fractional-h at any instant of time; and the radiation wave field emitted over time stretches a wave train of finite length. The total system of the source and radiation field maintains at any time (integer n times) one whole energy quantum, (n×) h× frequency, in complete accordance with

  9. Fracture mechanics

    CERN Document Server

    Perez, Nestor

    2017-01-01

    The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...

  10. Analytical mechanics

    CERN Document Server

    Lemos, Nivaldo A

    2018-01-01

    Analytical mechanics is the foundation of many areas of theoretical physics including quantum theory and statistical mechanics, and has wide-ranging applications in engineering and celestial mechanics. This introduction to the basic principles and methods of analytical mechanics covers Lagrangian and Hamiltonian dynamics, rigid bodies, small oscillations, canonical transformations and Hamilton–Jacobi theory. This fully up-to-date textbook includes detailed mathematical appendices and addresses a number of advanced topics, some of them of a geometric or topological character. These include Bertrand's theorem, proof that action is least, spontaneous symmetry breakdown, constrained Hamiltonian systems, non-integrability criteria, KAM theory, classical field theory, Lyapunov functions, geometric phases and Poisson manifolds. Providing worked examples, end-of-chapter problems, and discussion of ongoing research in the field, it is suitable for advanced undergraduate students and graduate students studying analyt...

  11. Engineering mechanics

    CERN Document Server

    Gross, Dietmar; Schröder, Jörg; Wall, Wolfgang A; Rajapakse, Nimal

    Statics is the first volume of a three-volume textbook on Engineering Mechanics. The authors, using a time-honoured straightforward and flexible approach, present the basic concepts and principles of mechanics in the clearest and simplest form possible to advanced undergraduate engineering students of various disciplines and different educational backgrounds. An important objective of this book is to develop problem solving skills in a systematic manner. Another aim of this volume is to provide engineering students as well as practising engineers with a solid foundation to help them bridge the gap between undergraduate studies on the one hand and advanced courses on mechanics and/or practical engineering problems on the other. The book contains numerous examples, along with their complete solutions. Emphasis is placed upon student participation in problem solving. The contents of the book correspond to the topics normally covered in courses on basic engineering mechanics at universities and colleges. Now in i...

  12. Supersymmetric mechanics

    International Nuclear Information System (INIS)

    Stelle, Kellogg S

    2007-01-01

    With the development of the electronic archives in high-energy physics, there has been increasing questioning of the role of traditional publishing styles, particularly in the production of conference books. One aspect of traditional publishing that still receives wide appreciation, however, is in the production of well-focussed pedagogical material. The present two-volume edition, 'Supersymmetric Mechanics-Vol 1', edited by S Bellucci and 'Supersymmetric Mechanics-Vol 2', edited by S Bellucci, S Ferrara and A Marrani, is a good example of the kind of well-digested presentation that should still find its way into university libraries. This two-volume set presents the material of a set of pedagogical lectures presented at the INFN National Laboratory in Frascati over a two-year period on the subject of supersymmetric mechanics. The articles include the results of discussions with the attending students after the lectures. Overall, this makes for a useful compilation of material on a subject that underlies much of the current effort in supersymmetric approaches to cosmology and the unification programme. The first volume comprises articles on 'A journey through garden algebras' by S Bellucci, S J Gates Jr and E Orazi on linear supermultiplet realizations in supersymmetric mechanics,'Supersymmetric mechanics in superspace' by S Bellucci and S Krivonos, 'Noncommutative mechanics, Landau levels, twistors and Yang-Mills amplitudes' by V P Nair, 'Elements of (super) Hamiltonian formalism' by A Nersessian and 'Matrix mechanics' by C Sochichiu. The second volume consists entirely of a masterful presentation on 'The attractor mechanism and space time singularities' by S Ferrara. This presents a comprehensive and detailed overview of the structure of supersymmetric black hole solutions in supergravity, critical point structure in the scalar field moduli space and the thermodynamic consequences. This second volume alone makes the set a worthwhile addition to the research

  13. Soil Mechanics

    OpenAIRE

    Verruijt, A.

    2010-01-01

    This book is the text for the introductory course of Soil Mechanics in the Department of Civil Engineering of the Delft University of Technology, as I have given from 1980 until my retirement in 2002. It contains an introduction into the major principles and methods of soil mechanics, such as the analysis of stresses, deformations, and stability. The most important methods of determining soil parameters, in the laboratory and in situ, are also described. Some basic principles of applied mecha...

  14. Multifunctional, supramolecular, continuous artificial nacre fibres

    Science.gov (United States)

    Hu, Xiaozhen; Xu, Zhen; Gao, Chao

    2012-10-01

    Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized ``brick-and-mortar'' (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance.

  15. Disclinations, dislocations, and continuous defects: A reappraisal

    Science.gov (United States)

    Kleman, M.; Friedel, J.

    2008-01-01

    Disclinations were first observed in mesomorphic phases. They were later found relevant to a number of ill-ordered condensed-matter media involving continuous symmetries or frustrated order. Disclinations also appear in polycrystals at the edges of grain boundaries; but they are of limited interest in solid single crystals, where they can move only by diffusion climb and, owing to their large elastic stresses, mostly appear in close pairs of opposite signs. The relaxation mechanisms associated with a disclination in its creation, motion, and change of shape involve an interplay with continuous or quantized dislocations and/or continuous disclinations. These are attached to the disclinations or are akin to Nye’s dislocation densities, which are particularly well suited for consideration here. The notion of an extended Volterra process is introduced, which takes these relaxation processes into account and covers different situations where this interplay takes place. These concepts are illustrated by a variety of applications in amorphous solids, mesomorphic phases, and frustrated media in their curved habit space. These often involve disclination networks with specific node conditions. The powerful topological theory of line defects considers only defects stable against any change of boundary conditions or relaxation processes compatible with the structure considered. It can be seen as a simplified case of the approach considered here, particularly suited for media of high plasticity or/and complex structures. It cannot analyze the dynamical properties of defects nor the elastic constants involved in their static properties; topological stability cannot guarantee energetic stability, and sometimes cannot distinguish finer details of the structure of defects.

  16. Leaching mechanisms

    International Nuclear Information System (INIS)

    Dougherty, D.R.; Colombo, P.

    1984-01-01

    Sufficient data are lacking to provide a basis for adequately assessing the long term leaching behavior of solidified low level radioactive waste forms in their disposal environment. Although the release of radioactivity from a waste form to an aqueous environment is recognized to be due to one or more mechanisms such as diffusion, dissolution, corrosion or ion exchange, the leaching mechanisms and the factors which control the leaching behavior of waste forms are not fully understood. This study will determine the prevailing mechanisms for a variety of selected LLW solidification agents which are being considered for use by defense and commercial generators and which will cover the broadest possible number of mechanisms. The investigation will proceed by the postulation of mathematical models representative of the prevailing mechanism(s) and the use of statistically designed experiments to test the actual leaching behavior of laborattory samples against the postulated representations. Maximum use of existing leach data in the literature will be made by incorporating literature results into a computerized data base along with the experimental results generated in this task

  17. From turnaround to continuous innovation

    DEFF Research Database (Denmark)

    Bjarnø, Ole-Christian

    2002-01-01

    In this article a five year longitudinal study performed at a medium-sized producer of electronics is reported during which we studied the company's change process. The paper deals with the concept of strategic sourcing as a component in turnaround change management. Based on theories of strategic...... sourcing, explorative case research and continuous innovation a series of findings is identified, and from these findings a management model is proposed. This model is intended to fill in an identified gap in the toolbox for maintenance and further development of the business partners network established...

  18. Drift vortices in continuous media

    International Nuclear Information System (INIS)

    Chernousenko, V.M.; Chernenko, I.V.; Chernyshenko, S.V.

    1989-01-01

    The work is devoted to investigation into the problems of large-scale cortex drift and generation in continuous media based on the solution of notably non-linear differential equations. Using the capability of the modern computer technique it is possible to consider a series of cases with regard to medium viscosity and its inhomogeneity and with regard to three-dimensional vortex nature. Based on the solutions obtained the large-scale steady-state vortex generation processes are considered. The results can be used when studying non-linear phenomena in plasma and processes of substance and energy transfer in non-equilibrium media. 16 refs.; 5 figs

  19. Roc curves for continuous data

    CERN Document Server

    Krzanowski, Wojtek J

    2009-01-01

    Since ROC curves have become ubiquitous in many application areas, the various advances have been scattered across disparate articles and texts. ROC Curves for Continuous Data is the first book solely devoted to the subject, bringing together all the relevant material to provide a clear understanding of how to analyze ROC curves.The fundamental theory of ROC curvesThe book first discusses the relationship between the ROC curve and numerous performance measures and then extends the theory into practice by describing how ROC curves are estimated. Further building on the theory, the authors prese

  20. Fuzzy extractors for continuous distributions

    OpenAIRE

    Buhan, I.R.; Doumen, J.M.; Hartel, Pieter H.; Veldhuis, Raymond N.J.

    2006-01-01

    We show that there is a direct relation between the maximum length of the keys extracted from biometric data and the error rates of the biometric system. The length of the bio-key depends on the amount of distinguishing information that can be extracted from the source data. This information can be used a-priori to evaluate the potential of the biometric data in the context of a specific cryptographic application. We model the biometric data more naturally as a continuous distribution and we ...

  1. FACTORS INFLUENCING CONTINUOUS ORGANISATIONAL CHANGE

    Directory of Open Access Journals (Sweden)

    Alexandru Rizescu

    2016-10-01

    Full Text Available Change involves the continuous adjustment to the external conditions of organizations in the operating environment, in parallel with the growth of domestic stability. This process constitutes the dilemma of change-stability, which can be tackled only through a vision of the future, meaning the idorganization of organization-environment interaction along with a flexible organizational structure, the use of advanced technology and the existence of a system of rewarding employees that reflects the values and priorities of both, organizational norms and individual needs.

  2. Theoretical physics 2 analytical mechanics

    CERN Document Server

    Nolting, Wolfgang

    2016-01-01

    This textbook offers a clear and comprehensive introduction to analytical mechanics, one of the core components of undergraduate physics courses.It follows on naturally from the previous volumes in this series, thus expanding the knowledge in classical mechanics. The book starts with a thorough introduction into Lagrangian mechanics, detailing the d’Alembert principle, Hamilton’s principle and conservation laws. It continues with an in-depth explanation of Hamiltonian mechanics, illustrated by canonical and Legendre transformation, the generalization to quantum mechanics through Poisson brackets and all relevant variational principles. Finally, the Hamilton-Jacobi theory and the transition to wave mechanics are presented in detail. Ideally suited to undergraduate students with some grounding in classical mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by ...

  3. A community continuity programme: volunteer faculty mentors and continuity learning.

    Science.gov (United States)

    McGeehan, John; English, Richard; Shenberger, Keith; Tracy, Gerald; Smego, Raymond

    2013-02-01

    Longitudinal generalist preceptorship experiences early in medical education can have beneficial effects on how students practise the art and science of medicine, regardless of their eventual career choices. We evaluated the first 2 years of implementation of an integrated, regional campus-based, early clinical experience programme, the Community Continuity Program, at our new community-based medical school that is under the supervision of volunteer primary care faculty members acting as continuity mentors (CMs). Curricular components for years 1 and 2 consisted of three annual 1-week community-based experiences with CMs, extensive physical diagnosis practice, interprofessional learning activities, a multigenerational family care experience, a mandatory Community Health Research Project (CHRP) in year 1 and a mandatory Quality Improvement Project in year 2. Outcome measures included student, faculty member and programme evaluations, student reflective narratives in portal-based e-journals, a Liaison Committee on Medical Education (LCME) self-study student survey and serial level-of-empathy surveys.   Students found all elements of this integrated community experience programme beneficial and worthwhile, especially the CMs and the use of standardised and real-life patients. CMs noted effective and professional student-patient interactions. The number of reflective e-journal postings per student during year1 ranged from 14 to 81 (mean, 47). Serial empathy questionnaires administered over 2 years demonstrated preservation of student empathy, and students believed that the programme had a positive effect on their personal level of empathy.   An integrative, longitudinal, community-based, early clinical experience programme driven by volunteer CMs provides patient-centered instruction for preclinical students in the clinical, social, behavioural, ethical and research foundations of medicine. © Blackwell Publishing Ltd 2013.

  4. Exploring the validity of the continuous assessment strategy in ...

    African Journals Online (AJOL)

    ... subject areas such as mathematics and science. This article outlines how a Continuous Assessment (CASS) mechanism introduced in the second year mathematics for civil engineering students at Technikon Witwatersrand could attain the desired goals. South African Journal of Higher Education Vol.18(2) 2004: 302-312 ...

  5. 40 CFR 60.256 - Continuous monitoring requirements.

    Science.gov (United States)

    2010-07-01

    ... facilities that use wet scrubber emission control equipment: (A) A monitoring device for the continuous measurement of the pressure loss through the venturi constriction of the control equipment. The monitoring... paragraph (c) of this section. (2) For mechanical vents with wet scrubbers, monitoring devices according to...

  6. Statistics of resonances in one-dimensional continuous systems

    Indian Academy of Sciences (India)

    Vol. 73, No. 3. — journal of. September 2009 physics pp. 565–572. Statistics of resonances in one-dimensional continuous systems. JOSHUA FEINBERG. Physics Department, University of Haifa at Oranim, Tivon 36006, Israel ..... relativistic quantum mechanics (Israel Program for Scientific Translations, Jerusalem,. 1969).

  7. Multiple applications of the Boussignac continuous positive airway pressure system

    NARCIS (Netherlands)

    Dieperink, Willem

    2008-01-01

    Continuous positive airway pressure, (CPAP) is a form of treatment to support patients with dyspnea. For the application of CPAP a mechanical ventilator or complex CPAP apparatus is mostly used. The Boussignac CPAP (BCPAP) system developed by George Boussignac does not need such apparatus. The BCPAP

  8. Strong negative self regulation of Prokaryotic transcription factors increases the intrinsic noise of protein expression

    Directory of Open Access Journals (Sweden)

    Jenkins Dafyd J

    2008-01-01

    Full Text Available Abstract Background Many prokaryotic transcription factors repress their own transcription. It is often asserted that such regulation enables a cell to homeostatically maintain protein abundance. We explore the role of negative self regulation of transcription in regulating the variability of protein abundance using a variety of stochastic modeling techniques. Results We undertake a novel analysis of a classic model for negative self regulation. We demonstrate that, with standard approximations, protein variance relative to its mean should be independent of repressor strength in a physiological range. Consequently, in that range, the coefficient of variation would increase with repressor strength. However, stochastic computer simulations demonstrate that there is a greater increase in noise associated with strong repressors than predicted by theory. The discrepancies between the mathematical analysis and computer simulations arise because with strong repressors the approximation that leads to Michaelis-Menten-like hyperbolic repression terms ceases to be valid. Because we observe that strong negative feedback increases variability and so is unlikely to be a mechanism for noise control, we suggest instead that negative feedback is evolutionarily favoured because it allows the cell to minimize mRNA usage. To test this, we used in silico evolution to demonstrate that while negative feedback can achieve only a modest improvement in protein noise reduction compared with the unregulated system, it can achieve good improvement in protein response times and very substantial improvement in reducing mRNA levels. Conclusion Strong negative self regulation of transcription may not always be a mechanism for homeostatic control of protein abundance, but instead might be evolutionarily favoured as a mechanism to limit the use of mRNA. The use of hyperbolic terms derived from quasi-steady-state approximation should also be avoided in the analysis of stochastic

  9. Building New Bridges between In Vitro and In Vivo in Early Drug Discovery: Where Molecular Modeling Meets Systems Biology.

    Science.gov (United States)

    Pearlstein, Robert A; McKay, Daniel J J; Hornak, Viktor; Dickson, Callum; Golosov, Andrei; Harrison, Tyler; Velez-Vega, Camilo; Duca, José

    2017-01-01

    Cellular drug targets exist within networked function-generating systems whose constituent molecular species undergo dynamic interdependent non-equilibrium state transitions in response to specific perturbations (i.e.. inputs). Cellular phenotypic behaviors are manifested through the integrated behaviors of such networks. However, in vitro data are frequently measured and/or interpreted with empirical equilibrium or steady state models (e.g. Hill, Michaelis-Menten, Briggs-Haldane) relevant to isolated target populations. We propose that cells act as analog computers, "solving" sets of coupled "molecular differential equations" (i.e. represented by populations of interacting species)via "integration" of the dynamic state probability distributions among those populations. Disconnects between biochemical and functional/phenotypic assays (cellular/in vivo) may arise with targetcontaining systems that operate far from equilibrium, and/or when coupled contributions (including target-cognate partner binding and drug pharmacokinetics) are neglected in the analysis of biochemical results. The transformation of drug discovery from a trial-and-error endeavor to one based on reliable design criteria depends on improved understanding of the dynamic mechanisms powering cellular function/dysfunction at the systems level. Here, we address the general mechanisms of molecular and cellular function and pharmacological modulation thereof. We outline a first principles theory on the mechanisms by which free energy is stored and transduced into biological function, and by which biological function is modulated by drug-target binding. We propose that cellular function depends on dynamic counter-balanced molecular systems necessitated by the exponential behavior of molecular state transitions under non-equilibrium conditions, including positive versus negative mass action kinetics and solute-induced perturbations to the hydrogen bonds of solvating water versus kT. Copyright© Bentham

  10. Earl occurring and continuing effects

    International Nuclear Information System (INIS)

    Scott, B.R.; Hahn, F.F.

    1989-01-01

    This chapter develops health-risk models for early and continuing effects of exposure to beta or gamma radiation that could be associated with light water nuclear power plant accidents. The main purpose of the chapter is to provide details on each health-risk model and on the data used. Early and continuing effects considered are prodromal symptoms and nonneoplastic diseases that usually occur soon after a brief radiation exposure. These effects are generally associated with relatively high (greater than 1 Gy) absorbed organ doses. For most of the effects considered, there is an absorbed organ dose threshold below which no effects are seen. Some information is provided on health effects observed in victims of the Chernobyl power plant accident. Organs of primary interest, because of their high sensitivity or their potential for receiving large doses, are bone marrow, gastrointestinal tract, thyroid glands, lungs, skin, gonads, and eyes. Exposure of the fetus is also considered. Additional data and modeling techniques available since publication of the Reactor Safety Study were used to obtain models for morbidity and mortality

  11. Early occurring and continuing effects

    International Nuclear Information System (INIS)

    Scott, B.R.; Hahn, F.F.

    1985-01-01

    This chapter deals with health-risk estimates for early and continuing effects of exposure to ionizing radiations that could be associated with light water nuclear power plants accidents. Early and continuing effects considered are nonneoplastic diseases and symptoms that normally occur soon after radiation exposure, but may also occur after years have passed. They are generally associated with relatively high (greater than 1 Gy) doses. For most of the effects considered, there is a practical dose threshold. Organs of primary interest, because of their high sensitivity or the likelihood of receiving a large radiation dose, are bone marrow, gastrointestinal tract, thyroid glands, lungs, skin, gonads, and eyes. In utero exposure of the fetus is also considered. New data and modeling techniques available since publication of the Reactor Safety Study (WASH 1400, 1975) were used along with data cited in the Study to develop improved health-risk models for morbidity and mortality. The new models are applicable to a broader range of accident scenarios, provide a more detailed treatment of dose protraction effects, and include morbidity effects not considered in the Reactor Safety Study. 115 references, 20 figures, 19 tables

  12. Accelerator based continuous neutron source.

    CERN Document Server

    Shapiro, S M; Ruggiero, A G

    2003-01-01

    Until the last decade, most neutron experiments have been performed at steady-state, reactor-based sources. Recently, however, pulsed spallation sources have been shown to be very useful in a wide range of neutron studies. A major review of neutron sources in the US was conducted by a committee chaired by Nobel laureate Prof. W. Kohn: ''Neutron Sources for America's Future-BESAC Panel on Neutron Sources 1/93''. This distinguished panel concluded that steady state and pulsed sources are complementary and that the nation has need for both to maintain a balanced neutron research program. The report recommended that both a new reactor and a spallation source be built. This complementarity is recognized worldwide. The conclusion of this report is that a new continuous neutron source is needed for the second decade of the 20 year plan to replace aging US research reactors and close the US neutron gap. it is based on spallation production of neutrons using a high power continuous superconducting linac to generate pr...

  13. Continuous Risk Management: An Overview

    Science.gov (United States)

    Rosenberg, Linda; Hammer, Theodore F.

    1999-01-01

    Software risk management is important because it helps avoid disasters, rework, and overkill, but more importantly because it stimulates win-win situations. The objectives of software risk management are to identify, address, and eliminate software risk items before they become threats to success or major sources of rework. In general, good project managers are also good managers of risk. It makes good business sense for all software development projects to incorporate risk management as part of project management. The Software Assurance Technology Center (SATC) at NASA GSFC has been tasked with the responsibility for developing and teaching a systems level course for risk management that provides information on how to implement risk management. The course was developed in conjunction with the Software Engineering Institute at Carnegie Mellon University, then tailored to the NASA systems community. This is an introductory tutorial to continuous risk management based on this course. The rational for continuous risk management and how it is incorporated into project management are discussed. The risk management structure of six functions is discussed in sufficient depth for managers to understand what is involved in risk management and how it is implemented. These functions include: (1) Identify the risks in a specific format; (2) Analyze the risk probability, impact/severity, and timeframe; (3) Plan the approach; (4) Track the risk through data compilation and analysis; (5) Control and monitor the risk; (6) Communicate and document the process and decisions.

  14. Continuous auditing: A literature review

    Directory of Open Access Journals (Sweden)

    Flávia Cruz de Souza

    2008-09-01

    Full Text Available Recent fraud scandals involving highly known corporations like Enron, WorldCom, and Xerox have eroded public confidence in financial reporting. At the same time, the auditing profession has suffered a big hit. In this scenario, Continuous Auditing (CA seems to have emerged as a response to recover the credibility of the auditing profession as well as meeting Sarbanes-Oxley (SOX requirements. This study, that adopts an exploratory approach, analyzes the existing literature on this topic. First, we address the concepts, models and implications of CA. After, throughout a search on the journals indexed at the CAPES's Basis, a literature review is conducted. A total of 57 articles were selected. We analyze authorship, affiliation, publications, year and type of research of papers that have addressed CA. Findings evidence that most articles addressing CA are non-empirical and adopt a conceptual approach. Also, there is an increasing tendency of continuous auditing studies. Rutgers University seems to be the World's leading research center on CA. This study aims to contribute to the Accounting Science by evidencing possibilities for research and publication in CA.

  15. Operculina from the northwestern Pacific (Sesoko Island, Japan) Species Differentiation, Population Dynamics, Growth and Development

    Science.gov (United States)

    Woeger, Julia; Eder, Wolfgang; Kinoshita, Shunichi; Briguglio, Antonino; Hohenegger, Johann

    2017-04-01

    During the last decades larger benthic foraminifera have gained importance as indicator species and are used in a variety of applications, from ecological monitoring, studying the effects of ocean acidification, or reconstructing paleoenvironments. They significantly contribute to the carbonate budget of costal areas and are invaluable tools in biostratigraphy. Even before their advancement as bioindicators, laboratory experiments have been conducted to investigate the effects of various ecological parameters on community composition, biology of single species, or investigating the effects of salinity and temperature on stable isotope composition of the foraminiferal test, to name only a few. The natural laboratory approach (continuous sampling over a period of more than one year) was conducted at the island of Sesoko (Okinawa, Japan). in combination with µ-CT scanning was used to reveal population dynamics of 3 different morphotypes of Operculina. The clarification of reproductive cycles as well as generation and size abundances were used to calculate natural growth models. Best fit was achieved using Bertalanffy and Michaelis-Menten functions. Exponential-, logistic-, generalized logistic-, Gompertz-function yielded weaker fits, when compared by coefficient of determination as well as Akaike Information criterion. The resulting growth curves and inferred growth rates were in turn used to evaluate the quality of a laboratory cultivation experiment carried out simultaneously over a period of 15 months. Culturing parameters such as temperature, light intensities, salinity and pH and light-dark duration were continuously adapted to measurements in the field. The average investigation time in culture was 77days. 13 Individuals lived more than 200 days, 3 reproduced asexually and one sexually. 14% of 186 Individuals were lost, while 22% could not be kept alive for more than one month. Growth curves also represent an instrumental source of information for the various

  16. Mechanisms of mechanical strain memory in airway smooth muscle.

    Science.gov (United States)

    Kim, Hak Rim; Hai, Chi-Ming

    2005-10-01

    We evaluated the hypothesis that mechanical deformation of airway smooth muscle induces structural remodeling of airway smooth muscle cells, thereby modulating mechanical performance in subsequent contractions. This hypothesis implied that past experience of mechanical deformation was retained (or "memorized") as structural changes in airway smooth muscle cells, which modulated the cell's subsequent contractile responses. We termed this phenomenon mechanical strain memory. Preshortening has been found to induce attenuation of both force and isotonic shortening velocity in cholinergic receptor-activated airway smooth muscle. Rapid stretching of cholinergic receptor-activated airway smooth muscle from an initial length to a final length resulted in post-stretch force and myosin light chain phosphorylation that correlated significantly with initial length. Thus post-stretch muscle strips appeared to retain memory of the initial length prior to rapid stretch (mechanical strain memory). Cytoskeletal recruitment of actin- and integrin-binding proteins and Erk 1/2 MAPK appeared to be important mechanisms of mechanical strain memory. Sinusoidal length oscillation led to force attenuation during oscillation and in subsequent contractions in intact airway smooth muscle, and p38 MAPK appeared to be an important mechanism. In contrast, application of local mechanical strain to cultured airway smooth muscle cells induced local actin polymerization and cytoskeletal stiffening. It is conceivable that deep inspiration-induced bronchoprotection may be a manifestation of mechanical strain memory such that mechanical deformation from past breathing cycles modulated the mechanical performance of airway smooth muscle in subsequent cycles in a continuous and dynamic manner.

  17. On obtaining classical mechanics from quantum mechanics

    International Nuclear Information System (INIS)

    Date, Ghanashyam

    2007-01-01

    Constructing a classical mechanical system associated with a given quantum-mechanical one entails construction of a classical phase space and a corresponding Hamiltonian function from the available quantum structures and a notion of coarser observations. The Hilbert space of any quantum-mechanical system naturally has the structure of an infinite-dimensional symplectic manifold ('quantum phase space'). There is also a systematic, quotienting procedure which imparts a bundle structure to the quantum phase space and extracts a classical phase space as the base space. This works straightforwardly when the Hilbert space carries weakly continuous representation of the Heisenberg group and one recovers the linear classical phase space R 2N . We report on how the procedure also allows extraction of nonlinear classical phase spaces and illustrate it for Hilbert spaces being finite dimensional (spin-j systems), infinite dimensional but separable (particle on a circle) and infinite dimensional but non-separable (polymer quantization). To construct a corresponding classical dynamics, one needs to choose a suitable section and identify an effective Hamiltonian. The effective dynamics mirrors the quantum dynamics provided the section satisfies conditions of semiclassicality and tangentiality

  18. Quantum mechanics

    CERN Document Server

    Fitzpatrick, Richard

    2015-01-01

    Quantum mechanics was developed during the first few decades of the twentieth century via a series of inspired guesses made by various physicists, including Planck, Einstein, Bohr, Schroedinger, Heisenberg, Pauli, and Dirac. All these scientists were trying to construct a self-consistent theory of microscopic dynamics that was compatible with experimental observations. The purpose of this book is to present quantum mechanics in a clear, concise, and systematic fashion, starting from the fundamental postulates, and developing the theory in as logical manner as possible. Topics covered in the book include the fundamental postulates of quantum mechanics, angular momentum, time-dependent and time-dependent perturbation theory, scattering theory, identical particles, and relativistic electron theory.

  19. Analytical mechanics

    CERN Document Server

    Helrich, Carl S

    2017-01-01

    This advanced undergraduate textbook begins with the Lagrangian formulation of Analytical Mechanics and then passes directly to the Hamiltonian formulation and the canonical equations, with constraints incorporated through Lagrange multipliers. Hamilton's Principle and the canonical equations remain the basis of the remainder of the text. Topics considered for applications include small oscillations, motion in electric and magnetic fields, and rigid body dynamics. The Hamilton-Jacobi approach is developed with special attention to the canonical transformation in order to provide a smooth and logical transition into the study of complex and chaotic systems. Finally the text has a careful treatment of relativistic mechanics and the requirement of Lorentz invariance. The text is enriched with an outline of the history of mechanics, which particularly outlines the importance of the work of Euler, Lagrange, Hamilton and Jacobi. Numerous exercises with solutions support the exceptionally clear and concise treatment...

  20. Quantum mechanics

    CERN Document Server

    Ghosh, P K

    2014-01-01

    Quantum mechanics, designed for advanced undergraduate and graduate students of physics, mathematics and chemistry, provides a concise yet self-contained introduction to the formal framework of quantum mechanics, its application to physical problems and the interpretation of the theory. Starting with a review of some of the necessary mathematics, the basic concepts are carefully developed in the text. After building a general formalism, detailed treatment of the standard material - the harmonic oscillator, the hydrogen atom, angular momentum theory, symmetry transformations, approximation methods, identical particle and many-particle systems, and scattering theory - is presented. The concluding chapter discusses the interpretation of quantum mechanics. Some of the important topics discussed in the book are the rigged Hilbert space, deformation quantization, path integrals, coherent states, geometric phases, decoherene, etc. This book is characterized by clarity and coherence of presentation.

  1. Wave Mechanics or Wave Statistical Mechanics

    International Nuclear Information System (INIS)

    Qian Shangwu; Xu Laizi

    2007-01-01

    By comparison between equations of motion of geometrical optics and that of classical statistical mechanics, this paper finds that there should be an analogy between geometrical optics and classical statistical mechanics instead of geometrical mechanics and classical mechanics. Furthermore, by comparison between the classical limit of quantum mechanics and classical statistical mechanics, it finds that classical limit of quantum mechanics is classical statistical mechanics not classical mechanics, hence it demonstrates that quantum mechanics is a natural generalization of classical statistical mechanics instead of classical mechanics. Thence quantum mechanics in its true appearance is a wave statistical mechanics instead of a wave mechanics.

  2. Mechanical seals

    CERN Document Server

    Mayer, E

    1977-01-01

    Mechanical Seals, Third Edition is a source of practical information on the design and use of mechanical seals. Topics range from design fundamentals and test rigs to leakage, wear, friction and power, reliability, and special designs. This text is comprised of nine chapters; the first of which gives a general overview of seals, including various types of seals and their applications. Attention then turns to the fundamentals of seal design, with emphasis on six requirements that must be considered: sealing effectiveness, length of life, reliability, power consumption, space requirements, and c

  3. Statistical mechanics

    CERN Document Server

    Davidson, Norman

    2003-01-01

    Clear and readable, this fine text assists students in achieving a grasp of the techniques and limitations of statistical mechanics. The treatment follows a logical progression from elementary to advanced theories, with careful attention to detail and mathematical development, and is sufficiently rigorous for introductory or intermediate graduate courses.Beginning with a study of the statistical mechanics of ideal gases and other systems of non-interacting particles, the text develops the theory in detail and applies it to the study of chemical equilibrium and the calculation of the thermody

  4. Reliability and continuous regeneration model

    Directory of Open Access Journals (Sweden)

    Anna Pavlisková

    2006-06-01

    Full Text Available The failure-free function of an object is very important for the service. This leads to the interest in the determination of the object reliability and failure intensity. The reliability of an element is defined by the theory of probability.The element durability T is a continuous random variate with the probability density f. The failure intensity (tλ is a very important reliability characteristics of the element. Often it is an increasing function, which corresponds to the element ageing. We disposed of the data about a belt conveyor failures recorded during the period of 90 months. The given ses behaves according to the normal distribution. By using a mathematical analysis and matematical statistics, we found the failure intensity function (tλ. The function (tλ increases almost linearly.

  5. Zeolites with Continuously Tuneable Porosity**

    Science.gov (United States)

    Wheatley, Paul S; Chlubná-Eliášová, Pavla; Greer, Heather; Zhou, Wuzong; Seymour, Valerie R; Dawson, Daniel M; Ashbrook, Sharon E; Pinar, Ana B; McCusker, Lynne B; Opanasenko, Maksym; Čejka, Jiří; Morris, Russell E

    2014-01-01

    Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneable surface area and micropore volume over a wide range can be prepared. This means that a particular surface area or micropore volume can be precisely tuned. The range of porosity we can target covers the whole range of useful zeolite porosity: from small pores consisting of 8-rings all the way to extra-large pores consisting of 14-rings. PMID:25284344

  6. Continuous method of natrium purification

    International Nuclear Information System (INIS)

    Batoux, B.; Laurent-Atthalin, A.; Salmon, M.

    1975-01-01

    An improvement of the known method for the production of highly pure sodium from technically pure sodium which still contains several hundred ppm metallic impurities is proposed. These impurities, first of all Ca and Ba, are separated by oxidation with sodium peroxide. The continuous method is new which can also be performed on a technically large scale and which results in a degree of purity of less than 10 ppm Ca. Under N 2 -atmosphere, highly dispersed sodium peroxide is added to a flow of sodium, and at 100 0 C to 150 0 C, thoroughly mixed, the suspension is heated under turbulence to 200 0 C to 300 0 C, and the forming oxides are separated. Exact data for an optimum reaction guide as well as a flow diagram are supplied. (UWI) [de

  7. Continuously variable focal length lens

    Science.gov (United States)

    Adams, Bernhard W; Chollet, Matthieu C

    2013-12-17

    A material preferably in crystal form having a low atomic number such as beryllium (Z=4) provides for the focusing of x-rays in a continuously variable manner. The material is provided with plural spaced curvilinear, optically matched slots and/or recesses through which an x-ray beam is directed. The focal length of the material may be decreased or increased by increasing or decreasing, respectively, the number of slots (or recesses) through which the x-ray beam is directed, while fine tuning of the focal length is accomplished by rotation of the material so as to change the path length of the x-ray beam through the aligned cylindrical slows. X-ray analysis of a fixed point in a solid material may be performed by scanning the energy of the x-ray beam while rotating the material to maintain the beam's focal point at a fixed point in the specimen undergoing analysis.

  8. Production expansion continues to accelerate

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    This paper reports that Saudi Arabian Oil Co. (Saudi Aramco) is continuing its accelerated Crude Oil Expansion Program initiated in 1989 that aims at achieving a 10 million bpd productive capacity by 1995. In addition to major engineering, construction and renovation work related to production expansion, Saudi Aramco drilling and workover operations have been markedly expanded. Since January 1991, rig activity has doubled. As an indication of aging of Saudi production, projects include modernizing current injection water treatment facilities, installing a new seawater injection plant on the Persian Gulf, installing dewatering facilities in a number of locations and installing a pilot gas lift project. In addition, equipment orders indicate the new discoveries south of Riyadh may also need the assistance of water injection from inception of production

  9. Continuous method of natrium purification

    Energy Technology Data Exchange (ETDEWEB)

    Batoux, B; Laurent-Atthalin, A; Salmon, M

    1975-05-28

    An improvement of the known method for the production of highly pure sodium from technically pure sodium which still contains several hundred ppm metallic impurities is proposed. These impurities, first of all Ca and Ba, are separated by oxidation with sodium peroxide. The new continuous method can be performed on a technically large scale and results in a degree of purity of less than 10 ppm Ca. Under N/sub 2/ -atmosphere, highly dispersed sodium peroxide is added to a flow of sodium, and at 100/sup 0/C to 150/sup 0/C, thoroughly mixed, the suspension is heated under turbulence to 200/sup 0/C to 300/sup 0/C, and the forming oxides are separated. Exact data for an optimum reaction guide as well as a flow diagram are supplied.

  10. Sustaining motivation for continuous improvement

    DEFF Research Database (Denmark)

    Jørgensen, Frances; Kofoed, Lise Busk

    2007-01-01

    The objective of this article is to explore possibilities for improving motivation for participation in Continuous Improvement (CI). Due to a number of issues, for example, challenges with measuring outcomes of CI activities on performance, the inherent slower, incremental rather than big bang...... activities is an important issue for managers. The paper begins with a short description of CI, with an emphasis on barriers to successful implementation cited in the literature. Thereafter, a number of widely-acknowledged-albeit perhaps somewhat dated-theories of motivation are explored in relation...... to the elements of CI in practice. Based on their own experiences with CI implementation in numerous action-research based studies, the authors propose a scenario for motivating CI participation through emphasis on factors common to the presented motivational theories. The paper ends with insights into future...

  11. Continuous improvement of software quality

    International Nuclear Information System (INIS)

    Sivertsen, Terje

    1999-04-01

    The present report is the first Halden Work Report delivered from the OECD Halden Reactor Project's research activity on formal methods and software quality. Of particular concern in this activity is to reach a consensus between regulators, licensees and the nuclear industry on questions related to the effective, industrial use of formal methods. The report gives considerable attention to the importance of continuous improvement as a characteristic of a living software quality system, and to the need of providing a basis for software process/product quality integration. In particular, the report discusses these aspects from the perspectives of defect prevention, formal methods, Total Quality Management (TQM), and Bayesian Belief Nets. Another concern is to promote controlled experiments on the use of new methods, techniques, and tools. This is achieved partly by reviewing suggestions on the collection and experimental use of data, and by surveying a number of metrics believed to have some potential for comparison studies (author) (ml)

  12. Continuous improvement of pump seals

    International Nuclear Information System (INIS)

    Wong, W.; Eyvindson, A.; Rhodes, D.B.

    2003-01-01

    Pump seal reliability continues to be an area needing improvement and ongoing vigilance. Methods have been developed for identifying and assessing factors relating to seal performance, selecting the most relevant ones for a specific station, and then focusing on the most significant aspects and how to improve. Discussion invariably addresses maintenance practices, seal design, monitoring capabilities, operating conditions, transients, and pump and motor design. Success in reliability improvement requires ongoing dialogue among the station operators, pump manufacturers and seal designers. AECL CAN-seals lead the nuclear industry in reliability and seal life. They effectively save operators millions of dollars in outage time and person-rem. This paper describes some of the significant developments in AECL's ongoing program in seal R and D, as well as recent new installations following the most demanding seal qualification programs to date. (author)

  13. TEACHING AIDS – CONTINUITY, INTEGRATION

    Directory of Open Access Journals (Sweden)

    ABRUDAN Ovidiu

    2007-06-01

    Full Text Available For the authors of this paper, the teaching aids were and will always be a priority in their teaching activity. The contents of this paper is the result of a long strained period of efforts made to improve the teaching process, a period in which the teaching aids were permanently improved – as a result of attentively monitoring the students’ results. We can say that motivated students, who wanted to become mechanical engineers, used these teaching aids successfully in their learning activity.

  14. Participation in online continuing education.

    Science.gov (United States)

    Farrell, Barbara; Ward, Natalie; Jennings, Brad; Jones, Caitlin; Jorgenson, Derek; Gubbels-Smith, Ashley; Dolovich, Lisa; Kennie, Natalie

    2016-02-01

    The ADAPT (ADapting pharmacists' skills and Approaches to maximize Patients' drug Therapy effectiveness) e-learning programme requires weekly participation in module activities and facilitated discussion to support skill uptake. In this study, we sought to describe the extent and pattern of, satisfaction with and factors affecting participation in the initial programme offering and reasons for withdrawal. Mixed methods - convergent parallel approach. Participation was examined in qualitative data from discussion boards, assignments and action plans. Learner estimations of time commitment and action plan submission rates were calculated. Surveys (Likert scale and open-ended questions) included mid-point and final, exit and participation surveys. Eleven of 86 learners withdrew, most due to time constraints (eight completed an exit survey; seven said they would take ADAPT again). Thirty-five of 75 remaining learners completed a participation survey. Although 50-60% of the remaining 75 learners actively continued participating, only 15/35 respondents felt satisfied with their own participation. Learners spent 3-5 h/week (average) on module activities. Factors challenging participation included difficulty with technology, managing time and group work. Factors facilitating participation included willingness to learn (content of high interest) and supportive work environment. Being informed of programme time scheduling in advance was identified as a way to enhance participation. This study determined extent of learner participation in an online pharmacist continuing education programme and identified factors influencing participation. Interactions between learners and the online interface, content and with other learners are important considerations for designing online education programmes. Recommendations for programme changes were incorporated following this evaluation to facilitate participation. © 2015 Royal Pharmaceutical Society.

  15. Analytical Assessment for Transient Stability Under Stochastic Continuous Disturbances

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Ping [Hohai Univ., Nanjing (China); Li, Hongyu [Hohai Univ., Nanjing (China); Gan, Chun [The Univ. of Tennessee, Knoxville, TN (United States); Liu, Yong [The Univ. of Tennessee, Knoxville, TN (United States); Yu, Yiping [Hohai Univ., Nanjing (China); Liu, Yilu [Univ. of Tennessee, Knoxville, TN (United States)

    2017-06-28

    Here, with the growing integration of renewable power generation, plug-in electric vehicles, and other sources of uncertainty, increasing stochastic continuous disturbances are brought to power systems. The impact of stochastic continuous disturbances on power system transient stability attracts significant attention. To address this problem, this paper proposes an analytical assessment method for transient stability of multi-machine power systems under stochastic continuous disturbances. In the proposed method, a probability measure of transient stability is presented and analytically solved by stochastic averaging. Compared with the conventional method (Monte Carlo simulation), the proposed method is many orders of magnitude faster, which makes it very attractive in practice when many plans for transient stability must be compared or when transient stability must be analyzed quickly. Also, it is found that the evolution of system energy over time is almost a simple diffusion process by the proposed method, which explains the impact mechanism of stochastic continuous disturbances on transient stability in theory.

  16. LSA Large Area Silicon Sheet Task Continuous Czochralski Process Development

    Science.gov (United States)

    Rea, S. N.

    1979-01-01

    A commercial Czochralski crystal growing furnace was converted to a continuous growth facility by installation of a small, in-situ premelter with attendant silicon storage and transport mechanisms. Using a vertical, cylindrical graphite heater containing a small fused quartz test tube linear from which the molten silicon flowed out the bottom, approximately 83 cm of nominal 5 cm diamter crystal was grown with continuous melt addition furnished by the test tube premelter. High perfection crystal was not obtained, however, due primarily to particulate contamination of the melt. A major contributor to the particulate problem was severe silicon oxide buildup on the premelter which would ultimately drop into the primary melt. Elimination of this oxide buildup will require extensive study and experimentation and the ultimate success of continuous Czochralski depends on a successful solution to this problem. Economically, the continuous Czochralski meets near-term cost goals for silicon sheet material.

  17. Evidence of structurally continuous collagen fibrils in tendon

    DEFF Research Database (Denmark)

    Svensson, Rene B; Herchenhan, Andreas; Starborg, Tobias

    2017-01-01

    favor continuity. This study initially set out to trace the full length of individual fibrils in adult human tendons, using serial block face-scanning electron microscopy. But even with this advanced technique the required length could not be covered. Instead a statistical approach was used on a large...... volume of fibrils in shorter image stacks. Only a single end was observed after tracking 67.5 mm of combined fibril lengths, in support of fibril continuity. To shed more light on this observation, the full length of a short tendon (mouse stapedius, 125 μm) was investigated and continuity of individual...... fibrils was confirmed. In light of these results, possible mechanisms that could reconcile the opposing findings on fibril continuity are discussed. STATEMENT OF SIGNIFICANCE: Connective tissues hold all parts of the body together and are mostly constructed from thin threads of the protein collagen...

  18. One-dimensional Brownian motion of charged nanoparticles along microtubules: a model system for weak binding interactions.

    Science.gov (United States)

    Minoura, Itsushi; Katayama, Eisaku; Sekimoto, Ken; Muto, Etsuko

    2010-04-21

    Various proteins are known to exhibit one-dimensional Brownian motion along charged rodlike polymers, such as microtubules (MTs), actin, and DNA. The electrostatic interaction between the proteins and the rodlike polymers appears to be crucial for one-dimensional Brownian motion, although the underlying mechanism has not been fully clarified. We examined the interactions of positively-charged nanoparticles composed of polyacrylamide gels with MTs. These hydrophilic nanoparticles bound to MTs and displayed one-dimensional Brownian motion in a charge-dependent manner, which indicates that nonspecific electrostatic interaction is sufficient for one-dimensional Brownian motion. The diffusion coefficient decreased exponentially with an increasing particle charge (with the exponent being 0.10 kBT per charge), whereas the duration of the interaction increased exponentially (exponent of 0.22 kBT per charge). These results can be explained semiquantitatively if one assumes that a particle repeats a cycle of binding to and movement along an MT until it finally dissociates from the MT. During the movement, a particle is still electrostatically constrained in the potential valley surrounding the MT. This entire process can be described by a three-state model analogous to the Michaelis-Menten scheme, in which the two parameters of the equilibrium constant between binding and movement, and the rate of dissociation from the MT, are derived as a function of the particle charge density. This study highlights the possibility that the weak binding interactions between proteins and rodlike polymers, e.g., MTs, are mediated by a similar, nonspecific charge-dependent mechanism. Copyright 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Metabolic dynamics in skeletal muscle during acute reduction in blood flow and oxygen supply to mitochondria: in-silico studies using a multi-scale, top-down integrated model.

    Science.gov (United States)

    Dash, Ranjan K; Li, Yanjun; Kim, Jaeyeon; Beard, Daniel A; Saidel, Gerald M; Cabrera, Marco E

    2008-09-09

    Control mechanisms of cellular metabolism and energetics in skeletal muscle that may become evident in response to physiological stresses such as reduction in blood flow and oxygen supply to mitochondria can be quantitatively understood using a multi-scale computational model. The analysis of dynamic responses from such a model can provide insights into mechanisms of metabolic regulation that may not be evident from experimental studies. For the purpose, a physiologically-based, multi-scale computational model of skeletal muscle cellular metabolism and energetics was developed to describe dynamic responses of key chemical species and reaction fluxes to muscle ischemia. The model, which incorporates key transport and metabolic processes and subcellular compartmentalization, is based on dynamic mass balances of 30 chemical species in both capillary blood and tissue cells (cytosol and mitochondria) domains. The reaction fluxes in cytosol and mitochondria are expressed in terms of a general phenomenological Michaelis-Menten equation involving the compartmentalized energy controller ratios ATP/ADP and NADH/NAD(+). The unknown transport and reaction parameters in the model are estimated simultaneously by minimizing the differences between available in vivo experimental data on muscle ischemia and corresponding model outputs in coupled with the resting linear flux balance constraints using a robust, nonlinear, constrained-based, reduced gradient optimization algorithm. With the optimal parameter values, the model is able to simulate dynamic responses to reduced blood flow and oxygen supply to mitochondria associated with muscle ischemia of several key metabolite concentrations and metabolic fluxes in the subcellular cytosolic and mitochondrial compartments, some that can be measured and others that can not be measured with the current experimental techniques. The model can be applied to test complex hypotheses involving dynamic regulation of cellular metabolism and

  20. Insight into the recognition, binding, and reactivity of catalytic metallodrugs targeting stem loop IIb of hepatitis C IRES RNA.

    Science.gov (United States)

    Bradford, Seth S; Ross, Martin James; Fidai, Insiya; Cowan, James A

    2014-06-01

    The complex Cu-GGHYrFK-amide (1-Cu) was previously reported as a novel metallotherapeutic that catalytically inactivates stem loop IIb (SLIIb) of the hepatitis C virus (HCV) internal ribosomal entry site (IRES) RNA and demonstrates significant antiviral activity in a cellular HCV replicon assay. Herein we describe additional studies focused on understanding the cleavage mechanism as well as the relationship of catalyst configuration to structural recognition and site-selective cleavage of the structured RNA motif. These are advanced by use of a combination of MALDI-TOF mass spectrometry, melting temperature determinations, and computational analysis to develop a structural model for binding and reactivity toward SLIIb of the IRES RNA. In addition, the binding, reactivity, and structural chemistry of the all-D-amino acid form of this metallopeptide, complex 2-Cu, are reported and compared with those of complex 1-Cu. In vitro RNA binding and cleavage assays for complex 2-Cu show a KD value of 76 ± 3 nM, and Michaelis-Menten parameters of kcat =0.14 ± 0.01 min(-1) and KM =7.9 ± 1.2 μM, with a turnover number exceeding 40. In a luciferase-based cellular replicon assay Cu-GGhyrfk-amide shows activity similar to that of the 1-Cu parent peptide, with an IC50 value of 1.9 ± 0.4 μM and cytotoxicity exceeding 100 μM. RT-PCR experiments confirm a significant decrease in HCV RNA levels in replicon assays for up to nine days when treated with complex 1-Cu in three-day dosing increments. This study shows the influence that the α-carbon stereocenter has for this new class of compounds, while detailed mass spectrometry and computational analyses provide new insight into the mechanisms of recognition, binding, and reactivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.