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Sample records for michaelis-menten constant km

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  4. The Michaelis-Menten-Stueckelberg Theorem

    Directory of Open Access Journals (Sweden)

    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.

  5. 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…

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

    Science.gov (United States)

    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.

  7. 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...

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

  11. 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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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).

  20. 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…

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

    Science.gov (United States)

    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.)

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

    Science.gov (United States)

    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…

  3. 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...

  4. 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)

  5. 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 ...

  6. Kinetics of Butyrate, Acetate, and Hydrogen Metabolism in a Thermophilic, Anaerobic, Butyrate-Degrading Triculture

    OpenAIRE

    Ahring, Birgitte K.; Westermann, Peter

    1987-01-01

    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, Km, for butyrate, acetate, and dissolved hyd...

  7. Mechanistic kinetic modeling generates system-independent P-glycoprotein mediated transport elementary rate constants for inhibition and, in combination with 3D SIM microscopy, elucidates the importance of microvilli morphology on P-glycoprotein mediated efflux activity.

    Science.gov (United States)

    Ellens, Harma; Meng, Zhou; Le Marchand, Sylvain J; Bentz, Joe

    2018-06-01

    In vitro transporter kinetics are typically analyzed by steady-state Michaelis-Menten approximations. However, no clear evidence exists that these approximations, applied to multiple transporters in biological membranes, yield system-independent mechanistic parameters needed for reliable in vivo hypothesis generation and testing. Areas covered: The classical mass action model has been developed for P-glycoprotein (P-gp) mediated transport across confluent polarized cell monolayers. Numerical integration of the mass action equations for transport using a stable global optimization program yields fitted elementary rate constants that are system-independent. The efflux active P-gp was defined by the rate at which P-gp delivers drugs to the apical chamber, since as much as 90% of drugs effluxed by P-gp partition back into nearby microvilli prior to reaching the apical chamber. The efflux active P-gp concentration was 10-fold smaller than the total expressed P-gp for Caco-2 cells, due to their microvilli membrane morphology. The mechanistic insights from this analysis are readily extrapolated to P-gp mediated transport in vivo. Expert opinion: In vitro system-independent elementary rate constants for transporters are essential for the generation and validation of robust mechanistic PBPK models. Our modeling approach and programs have broad application potential. They can be used for any drug transporter with minor adaptations.

  8. 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 ...

  9. 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...

  10. 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...

  11. Monitoring the enzymatic conversion of urea to ammonium by conventional or microchip capillary electrophoresis with contactless conductivity detection.

    Science.gov (United States)

    Schuchert-Shi, Aiping; Hauser, Peter C

    2008-05-15

    Capillary electrophoresis with contactless conductivity detection was used to directly quantify the ammonium produced in the enzymatic conversion of urea with urease. This allowed the characterization of the reaction without having to use more elaborate indirect optical methods for quantification. The maximum rate of reaction, V(max), was determined as 5.1 mmol x mL(-1) x min(-1), and the Michaelis-Menten constant, K(m), was determined as 16 mM. Furthermore, the method was successfully applied to the determination of urea in clinical samples of human blood by using a conventional capillary and a microchip device.

  12. Differential potassium influx influences growth of two cotton varieties in hydroponics

    International Nuclear Information System (INIS)

    Ali, L.; Maqsood, M.A.; Kanwal, S.; Aziz, T.

    2010-01-01

    Potassium uptake rate of two cotton (Gossypium hirsutum L.) varieties viz., NIBGE-2 and MNH-786 was investigated in nutrient solution culture having deficient K at the rate 0.3 mM and deficient K+ Na at the rate 0.3 +2.7 mM. Depletion of K from solution was monitored over a period of 24 h at regular time intervals after 0, 0.5, 1.0, 1.5, 2, 3, 4, 5, 6, 8, 10, 12 and 24 h to estimate K uptake kinetics of the roots i.e. maximum influx, I/sub max/ and the Michaelis-Menten constant, Km. NIBGE-2 had about 2-fold higher (2.0 mg g rdw-1 hr-1) I/sub max/ value for K uptake rate at deficient K+Na than that (1.207 mg g rdw-1 hr-1) for MNH-786. Higher, Michaelis-Menten constant, Km (12.82 ppm) for K uptake rate was observed in both cultivars NIBGE-2 and MNH-786 at deficient K+Na than that at deficient K. Main effects of treatments and varieties had significant (p< 0.05) effect on shoot dry matter, root dry matter, total dry matter and leaf area per plant. Maximum K influx in NIBGE-2 at deficient K and deficient K +Na was attributed to enhanced growth response as compared to that in MNH-786. (author)

  13. Use of CdSe/ZnS luminescent quantum dots incorporated within sol-gel matrix for urea detection.

    Science.gov (United States)

    Duong, Hong Dinh; Rhee, Jong Il

    2008-09-19

    In this work, urea detection techniques based on the pH sensitivity of CdSe/ZnS QDs were developed using three types of sol-gel membranes: a QD-entrapped membrane, urease-immobilized membrane and double layer consisting of a QD-entrapped membrane and urease-immobilized membrane. The surface morphology of the sol-gel membranes deposited on the wells in a 24-well microtiter plate was investigated. The linear detection range of urea was in the range of 0-10mM with the three types of sol-gel membranes. The urea detection technique based on the double layer consisting of the QD-entrapped membrane and urease-immobilized membrane resulted in the highest sensitivity to urea due to the Michaelis-Menten kinetic parameters. That is, the Michaelis-Menten constant (K(m)=2.0745mM) of the free urease in the QD-entrapped membrane was about 4-fold higher than that (K(m)=0.549mM) of the immobilized urease in the urease-immobilized membrane and about 12-fold higher than that (K(m)=0.1698mM) of the immobilized urease in the double layer. The good stability of the three sol-gel membranes for urea sensing over 2 months showed that the use of sol-gel membranes immobilized with QDs or an enzyme is suitable for biomedical and environmental applications.

  14. Quantifying stream nutrient uptake from ambient to saturation with instantaneous tracer additions

    Science.gov (United States)

    Covino, T. P.; McGlynn, B. L.; McNamara, R.

    2009-12-01

    Stream nutrient tracer additions and spiraling metrics are frequently used to quantify stream ecosystem behavior. However, standard approaches limit our understanding of aquatic biogeochemistry. Specifically, the relationship between in-stream nutrient concentration and stream nutrient spiraling has not been characterized. The standard constant rate (steady-state) approach to stream spiraling parameter estimation, either through elevating nutrient concentration or adding isotopically labeled tracers (e.g. 15N), provides little information regarding the stream kinetic curve that represents the uptake-concentration relationship analogous to the Michaelis-Menten curve. These standard approaches provide single or a few data points and often focus on estimating ambient uptake under the conditions at the time of the experiment. Here we outline and demonstrate a new method using instantaneous nutrient additions and dynamic analyses of breakthrough curve (BTC) data to characterize the full relationship between spiraling metrics and nutrient concentration. We compare the results from these dynamic analyses to BTC-integrated, and standard steady-state approaches. Our results indicate good agreement between these three approaches but we highlight the advantages of our dynamic method. Specifically, our new dynamic method provides a cost-effective and efficient approach to: 1) characterize full concentration-spiraling metric curves; 2) estimate ambient spiraling metrics; 3) estimate Michaelis-Menten parameters maximum uptake (Umax) and the half-saturation constant (Km) from developed uptake-concentration kinetic curves, and; 4) measure dynamic nutrient spiraling in larger rivers where steady-state approaches are impractical.

  15. A novel H(2)O(2) amperometric biosensor based on gold nanoparticles/self-doped polyaniline nanofibers.

    Science.gov (United States)

    Chen, Xiaojun; Chen, Zixuan; Zhu, Jinwei; Xu, Chenbin; Yan, Wei; Yao, Cheng

    2011-10-01

    A new kind of gold nanoparticles/self-doped polyaniline nanofibers (Au/SPAN) with grooves has been prepared for the immobilization of horseradish peroxidase (HRP) on the surface of glassy carbon electrode (GCE). The ratio of gold in the composite nanofibers was up to 64%, which could promote the conductivity and biocompatibility of SPAN and increase the immobilized amount of HRP molecules greatly. The electrode exhibits enhanced electrocatalytic activity in the reduction of H(2)O(2) in the presence of the mediator hydroquinone (HQ). The effects of concentration of HQ, solution pH and the working potential on the current response of the modified electrode toward H(2)O(2) were optimized to obtain the maximal sensitivity. The proposed biosensor exhibited a good linear response in the range from 10 to 2000 μM with a detection limit of 1.6 μM (S/N=3) under the optimum conditions. The response showed Michaelis-Menten behavior at larger H(2)O(2) concentrations, and the apparent Michaelis-Menten constant K(m) was estimated to be 2.21 mM. The detection of H(2)O(2) concentration in real sample showed acceptable accuracy with the traditional potassium permanganate titration. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. 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.

  17. Preparation of biosensors by immobilization of polyphenol oxidase in conducting copolymers and their use in determination of phenolic compounds in red wine.

    Science.gov (United States)

    Böyükbayram, A Elif; Kiralp, Senem; Toppare, Levent; Yağci, Yusuf

    2006-10-01

    Electrochemically produced graft copolymers of thiophene capped polytetrahydofuran (TPTHF1 and TPTHF2) and pyrrole were achieved by constant potential electrolysis using sodium dodecylsulfate (SDS) as the supporting electrolyte. Characterizations were based on Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Electrical conductivities were measured by the four-probe technique. Novel biosensors for phenolic compounds were constructed by immobilizing polyphenol oxidase (PPO) into conducting copolymers prepared by electropolymerization of pyrrole with thiophene capped polytetrahydrofuran. Kinetic parameters, maximum reaction rate (V(max)) and Michaelis-Menten constant (K(m)) and optimum conditions regarding temperature and pH were determined for the immobilized enzyme. Operational stability and shelf-life of the enzyme electrodes were investigated. Enzyme electrodes of polyphenol oxidase were used to determine the amount of phenolic compounds in two brands of Turkish red wines and found very useful owing to their high kinetic parameters and wide pH working range.

  18. A novel hydrogen peroxide biosensor based on hemoglobin-collagen-CNTs composite nanofibers.

    Science.gov (United States)

    Li, J; Mei, H; Zheng, W; Pan, P; Sun, X J; Li, F; Guo, F; Zhou, H M; Ma, J Y; Xu, X X; Zheng, Y F

    2014-06-01

    In this paper, carbon nanotubes (CNTs) were successfully incorporated in the composite composed of hemoglobin (Hb) and collagen using co-electrospinning technology. The formed Hb-collagen-CNTs composite nanofibers possessed distinct advantage of three-dimensional porous structure, biocompatibility and excellent stability. The Hb immobilized in the electrospun nanofibers retained its natural structure and the heterogeneous electron transfer rate constant (ks) of the direct electron transfer between Hb and electrodes was 5.3s(-1). In addition, the electrospun Hb-collagen-CNTs nanofibers modified electrodes showed good electrocatalytic properties toward H2O2 with a detection limit of 0.91μM (signal-to-noise ratio of 3) and the apparent Michaelis-Menten constant (Km(app)) of 32.6μM. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. 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

  20. Parallel synthesis of libraries of anodic and cathodic functionalized electrodeposition paints as immobilization matrix for amperometric biosensors.

    Science.gov (United States)

    Ngounou, Bertrand; Aliyev, Elchin H; Guschin, Dmitrii A; Sultanov, Yusif M; Efendiev, Ayaz A; Schuhmann, Wolfgang

    2007-09-01

    The integration of flexible anchoring groups bearing imidazolyl or pyridyl substituents into the structure of electrodeposition paints (EDP) is the basis for the parallel synthesis of a library containing 107 members of different cathodic and anodic EDPs with a high variation in polymer properties. The obtained EDPs were used as immobilization matrix for biosensor fabrication using glucose oxidase as a model enzyme. Amperometric glucose sensors based on the different EDPs showed a wide variation in their sensor characteristics with respect to the apparent Michaelis-Menten constant (KM(app)) representing the linear measuring range and the maximum current (Imax(app)). Based on these results first assumptions concerning the impact of different side chains in the EDP on the expected biosensor properties could be obtained allowing for an improved rational optimization of EDPs used as immobilization matrix in amperometric biosensors.

  1. Catalytic monolayer voltammetry and in situ scanning tunneling microscopy of copper nitrite reductase on cysteamine-modified Au(111) electrodes

    DEFF Research Database (Denmark)

    Zhang, Jingdong; Welinder, A.C.; Hansen, Allan Glargaard

    2003-01-01

    electrochemical scanning tunneling microscopy (in situ STM) directly in aqueous acetate buffer, pH 6.0 has been used. High-resolution in situ STM shows that cysteamine packs into ordered domains with strip features of a periodic distance of 11.7 +/- 0.3 Angstrom. No voltammetric signals of the nitrite substrate...... on this surface could be detected. A strong cathodic catalytic wave appears in the presence of nitrite. The catalytic current follows a Michaelis-Menten pattern with a Michaelis constant of K-m approximate to 44 muM, which is close to the value for AxCuNiR in homogeneous solution. The apparent catalytic rate...

  2. 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 ...

  3. 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 ...

  4. A highly efficient nano-cluster artificial peroxidase and its direct electrochemistry on a nano complex modified glassy carbon electrode.

    Science.gov (United States)

    Hong, Jun; Wang, Wei; Huang, Kun; Yang, Wei-Yun; Zhao, Ying-Xue; Xiao, Bao-Lin; Gao, Yun-Fei; Moosavi-Movahedi, Zainab; Ghourchian, Hedayatollah; Moosavi-Movahedi, Ali Akbar

    2012-01-01

    A nano-cluster with highly efficient peroxide activity was constructed based on nafion (NF) and cytochrome c (Cyt c). UV-Vis spectrometry and transmission electron microscopy (TEM) methods were utilized for characterization of the nano-structured enzyme or artificial peroxidase (AP). The nano-cluster was composed of a Chain-Ball structure, with an average ball size of about 40 nm. The Michaelis-Menten (K(m)) and catalytic rate (k(cat)) constants of the AP were determined to be 2.5 ± 0.4 µM and 0.069 ± 0.001 s(-1), respectively, in 50 mM PBS at pH 7.0. The catalytic efficiency of the AP was evaluated to be 0.028 ± 0.005 µM(-1) s(-1), which was 39 ± 5% as efficient as the native horseradish peroxidase (HRP). The AP was also immobilized on a functional multi-wall carbon nanotube (MWNCTs)-gold colloid nanoparticles (AuNPs) nano-complex modified glassy carbon (GC) electrode. The cyclic voltammetry of AP on the nano complex modified GC electrode showed a pair of well-defined redox peaks with a formal potential (E°') of -45 ± 2 mV (vs. Ag/AgCl) at a scan rate of 0.05 V/s. The heterogeneous electron transfer rate constant (k(s)) was evaluated to be 0.65 s(-1). The surface concentration of electroactive AP on GC electrode (Γ) was 7 × 10(-10) mol cm(-2). The apparent Michaelis-Menten constant (K(m)(app)) was 0.23 nM.

  5. 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

  6. Characterization of the human cytochrome P450 enzymes involved in the metabolism of dihydrocodeine

    Science.gov (United States)

    Kirkwood, L. C.; Nation, R. L.; Somogyi, A. A.

    1997-01-01

    Aims Using human liver microsomes from donors of the CYP2D6 poor and extensive metabolizer genotypes, the role of individual cytochromes P-450 in the oxidative metabolism of dihydrocodeine was investigated. Methods The kinetics of formation of N- and O-demethylated metabolites, nordihydrocodeine and dihydromorphine, were determined using microsomes from six extensive and one poor metabolizer and the effects of chemical inhibitors selective for individual P-450 enzymes of the 1A, 2A, 2C, 2D, 2E and 3A families and of LKM1 (anti-CYP2D6) antibodies were studied. Results Nordihydrocodeine was the major metabolite in both poor and extensive metabolizers. Kinetic constants for N-demethylation derived from the single enzyme Michaelis-Menten model did not differ between the two groups. Troleandomycin and erythromycin selectively inhibited N-demethylation in both extensive and poor metabolizers. The CYP3A inducer, α-naphthoflavone, increased N-demethylation rates. The kinetics of formation of dihydromorphine in both groups were best described by a single enzyme Michaelis-Menten model although inhibition studies in extensive metabolizers suggested involvement of two enzymes with similar Km values. The kinetic constants for O-demethylation were significantly different in extensive and poor metabolizers. The extensive metabolizers had a mean intrinsic clearance to dihydromorphine more than ten times greater than the poor metabolizer. The CYP2D6 chemical inhibitors, quinidine and quinine, and LKM1 antibodies inhibited O-demethylation in extensive metabolizers; no effect was observed in microsomes from a poor metabolizer. Conclusions CYP2D6 is the major enzyme mediating O-demethylation of dihydrocodeine to dihydromorphine. In contrast, nordihydrocodeine formation is predominantly catalysed by CYP3A. PMID:9431830

  7. 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.

  8. Phenytoin pharmacokinetics in critically ill trauma patients.

    Science.gov (United States)

    Boucher, B A; Rodman, J H; Jaresko, G S; Rasmussen, S N; Watridge, C B; Fabian, T C

    1988-12-01

    Preliminary data have suggested that phenytoin systemic clearance may increase during initial therapy in critically ill patients. The objectives for this study were to model the time-variant phenytoin clearance and evaluate concomitant changes in protein binding and urinary metabolite elimination. Phenytoin was given as an intravenous loading dose of 15 mg/kg followed by an initial maintenance dose of 6 mg/kg/day in 10 adult critically ill trauma patients. Phenytoin bound and unbound plasma concentrations were determined in 10 patients and urinary excretion of the metabolite p-hydroxyphenyl phenylhydantoin (p-HPPH) was measured in seven patients for 7 to 14 days. A Michaelis-Menten one-compartment model incorporating a time-variant maximal velocity (Vmax) was sufficient to describe the data and superior to a conventional time-invariant Michaelis-Menten model. Vmax for the time-variant model was defined as V'max + Vmax delta (1 - e(-kindt)). Vmax infinity is the value for Vmax when t is large. The median values (ranges) for the parameters were Km = 4.8 (2.6 to 20) mg/L, Vmax infinity = 1348 (372 to 4741) mg/day, and kind = 0.0115 (0.0045 to 0.132) hr-1. Phenytoin free fraction increased in a majority of patients during the study period, with a binding ratio inversely related to albumin. Measured urinary p-HPPH data were consistent with the proposed model. A loading and constant maintenance dose of phenytoin frequently yielded a substantial, clinically significant fall in plasma concentrations with a pattern of apparently increasing clearance that may be a consequence of changes in protein binding, induction of metabolism, or the influence of stress on hepatic metabolic capacity.

  9. Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters.

    Science.gov (United States)

    Bristow, Laura A; Dalsgaard, Tage; Tiano, Laura; Mills, Daniel B; Bertagnolli, Anthony D; Wright, Jody J; Hallam, Steven J; Ulloa, Osvaldo; Canfield, Donald E; Revsbech, Niels Peter; Thamdrup, Bo

    2016-09-20

    A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (Chile at manipulated O2 levels between 5 nmol⋅L(-1) and 20 μmol⋅L(-1) Rates of both processes were detectable in the low nanomolar range (5-33 nmol⋅L(-1) O2), but demonstrated a strong dependence on O2 concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L(-1) O2 for ammonium oxidation and 778 ± 168 nmol⋅L(-1) O2 for nitrite oxidation assuming one-component Michaelis-Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis-Menten model, indicating a high-affinity component with a Km of just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2 affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2 is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss.

  10. Nuclear constants

    International Nuclear Information System (INIS)

    Foos, J.

    1999-01-01

    This paper is written in two tables. The first one describes the different particles (bosons and fermions). The second one gives the isotopes nuclear constants of the different elements, for Z = 1 to 56. (A.L.B.)

  11. Nuclear constants

    International Nuclear Information System (INIS)

    Foos, J.

    2000-01-01

    This paper is written in two tables. The first one describes the different particles (bosons and fermions). The second one gives the isotopes nuclear constants of the different elements, for Z = 56 to 68. (A.L.B.)

  12. Nuclear constants

    International Nuclear Information System (INIS)

    Foos, J.

    1998-01-01

    This paper is made of two tables. The first table describes the different particles (bosons and fermions) while the second one gives the nuclear constants of isotopes from the different elements with Z = 1 to 25. (J.S.)

  13. Nuclear constants

    International Nuclear Information System (INIS)

    Foos, J.

    1999-01-01

    This paper is written in two tables. The first one describes the different particles (bosons and fermions). The second one gives the isotopes nuclear constants of the different elements, for Z = 56 to 68. (A.L.B.)

  14. Are fundamental constants really constant

    International Nuclear Information System (INIS)

    Norman, E.B.

    1986-01-01

    Reasons for suspecting that fundamental constants might change with time are reviewed. Possible consequences of such variations are examined. The present status of experimental tests of these ideas is discussed

  15. The Hubble Constant

    Directory of Open Access Journals (Sweden)

    Neal Jackson

    2015-09-01

    Full Text Available I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give H_0 values of around 72–74 km s^–1 Mpc^–1, with typical errors of 2–3 km s^–1 Mpc^–1. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67–68 km s^–1 Mpc^–1 and typical errors of 1–2 km s^–1 Mpc^–1. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.

  16. Geomagnetic Kn, Ks, Km Indices

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A full description of the indices Kn, Ks, Km is given in a monography,"Indices Kn, Ks et Km, 1964-1967", edited in 1968 by the Centre National de la Recherche...

  17. KM3NeT

    CERN Multimedia

    KM3NeT is a large scale next-generation neutrino telescope located in the deep waters of the Mediterranean Sea, optimized for the discovery of galactic neutrino sources emitting in the TeV energy region.

  18. Rapid Determination of Enzyme Kinetics from Fluorescence: Overcoming the Inner Filter Effect

    Science.gov (United States)

    Palmier, Mark O.; Van Doren, Steven R.

    2007-01-01

    Fluorescence change is convenient for monitoring enzyme kinetics. Unfortunately, it looses linearity as the absorbance of the fluorescent substrate increases with concentration. When the sum of absorbance at excitation and emission wavelengths exceeds 0.08, this inner filtering effect (IFE) alters apparent initial velocities, Km, and kcat. The IFE distortion of apparent initial velocities can be corrected without doing fluorophore dilution assays. Using the substrate’s extinction coefficients at excitation and emission wavelengths, the inner filter effect can be modeled during curve fitting for more accurate Michaelis-Menten parameters. A faster and simpler approach is to derive kcat and Km from progress curves. Strategies to obtain reliable and reproducible estimates of kcat and Km from only two or three progress curves are illustrated using matrix metalloproteinase-12 and alkaline phosphatase. Accurate estimates of concentration of enzyme active sites and specificity constant kcat/Km (from one progress curve with [S] ≪ Km) confer accuracy, freedom of choices of [S], and robustness to kcat and Km globally fitted to a few progress curves. The economies of the progress curve approach make accurate kcat and Km more accessible from fluorescence measurements. PMID:17706587

  19. KM-Appunti : 5. KM e "nuova" logica

    OpenAIRE

    Bogliolo, Domenico

    2002-01-01

    Paolo Bisogno leaved many tracks that must be catalogued. One of his research paths, Knowledge Management, is a sort of “Science of knowledge organization” if we decide to join the idea of knowledge with practical, managerial and directional components. We will try to outline here an operative and epistemologic layout of knowledge modelling and categorizing, helping us in understanding new knowledge boundaries of KM.

  20. Function of muscle-type lactate dehydrogenase and citrate synthase of the Galápagos marine iguana, Amblyrhynchus cristatus, in relation to temperature.

    Science.gov (United States)

    Fields, Peter A; Strothers, Chad M; Mitchell, Mark A

    2008-05-01

    The Galápagos marine iguana, Amblyrhynchus cristatus, is unique among lizards in foraging subtidally, leading to activity across a broad range of ambient temperatures ( approximately 14-40 degrees C). To determine whether the marine iguana shows any biochemical changes consistent with maintaining enzyme function at both warm and cold body temperatures, we examined the function of the aerobic enzyme citrate synthase (CS) and the muscle isoform of the anaerobic enzyme lactate dehydrogenase (A(4)-LDH) in A. cristatus and a confamilial species, Iguana iguana, from 14 to 46 degrees C. We also deduced amino acid sequences from cDNA of each enzyme. In CS, despite two amino acid substitutions, we found no difference in the apparent Michaelis-Menten constant K(m) of oxaloacetate at any temperature, indicating that the substrate affinity of CS in A. cristatus has not adapted to changes in thermal environment. In A(4)-LDH, we used site-directed mutagenesis to show that the substitutions T9A and I283V (A. cristatus --> I. iguana) individually have no effect on kinetics, but together significantly decrease the K(m) of pyruvate and catalytic rate constant (k(cat)) of the A. cristatus ortholog. Thus, our data show that A. cristatus A(4)-LDH has not become cold adapted in response to this species' aquatic foraging behavior, and instead may be consistent with moderate warm adaptation with respect to the I. iguana ortholog.

  1. A new thermophilic nitrilase from an antarctic hyperthermophilic microorganism.

    Directory of Open Access Journals (Sweden)

    Geraldine V. Dennett

    2016-02-01

    Full Text Available Several environmental samples from Antarctica were collected and enriched to search for microorganisms with nitrilase activity. A new thermostable nitrilase from a novel hyperthermophilic archaea Pyrococcus sp. M24D13 was purified and characterized. The activity of this enzyme increased as the temperatures rise from 70 up to 85 °C. Its optimal activity occurred at 85 °C and pH 7.5. This new enzyme shows a remarkable resistance to thermal inactivation retaining more than 50% of its activity even after 8 h of incubation at 85 °C.In addition, this nitrilase is highly versatile demonstrating activity towards different substrates such as benzonitrile (60 mM, aromatic nitrile and butyronitrile (60 mM, aliphatic nitrile, with a specific activity of 3286.7 U mg-1 of protein and 4008.2 U mg-1 of protein respectively. Moreover the enzyme NitM24D13 also presents cyanidase activity.The apparent Michaelis-Menten constant (Km and Vmáx of this Nitrilase for benzonitrile were 0.3 mM and 333.3 µM min-1, respectively, and the specificity constant (kcat/Km for benzonitrile was 2.05×105 s-1 M-1.

  2. 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.

  3. The Non-Linear Child: Ontogeny, Isoniazid Concentration, and NAT2 Genotype Modulate Enzyme Reaction Kinetics and Metabolism

    Directory of Open Access Journals (Sweden)

    Zoe Rogers

    2016-09-01

    Full Text Available N-acetyltransferase 2 (NAT2 catalyzes the acetylation of isoniazid to N-acetylisoniazid. NAT2 polymorphism explains 88% of isoniazid clearance variability in adults. We examined the effects of clinical and genetic factors on Michaelis-Menten reaction kinetic constants of maximum velocity (Vmax and affinity (Km in children 0–10 years old. We measured the rates of isoniazid elimination and N-acetylisoniazid production in the blood of 30 children. Since maturation effects could be non-linear, we utilized a pharmacometric approach and the artificial intelligence method, multivariate adaptive regression splines (MARS, to identify factors predicting NAT2 Vmax and Km by examining clinical, genetic, and laboratory factors in toto. Isoniazid concentration predicted both Vmax and Km and superseded the contribution of NAT2 genotype. Age non-linearly modified the NAT2 genotype contribution until maturation at ≥5.3 years. Thus, enzyme efficiency was constrained by substrate concentration, genes, and age. Since MARS output is in the form of basis functions and equations, it allows multiscale systems modeling from the level of cellular chemical reactions to whole body physiological parameters, by automatic selection of significant predictors by the algorithm.

  4. Electrochemical quantification of the antioxidant capacity of medicinal plants using biosensors.

    Science.gov (United States)

    Rodríguez-Sevilla, Erika; Ramírez-Silva, María-Teresa; Romero-Romo, Mario; Ibarra-Escutia, Pedro; Palomar-Pardavé, Manuel

    2014-08-08

    The working area of a screen-printed electrode, SPE, was modified with the enzyme tyrosinase (Tyr) using different immobilization methods, namely entrapment with water-soluble polyvinyl alcohol (PVA), cross-linking using glutaraldehyde (GA), and cross-linking using GA and human serum albumin (HSA); the resulting electrodes were termed SPE/Tyr/PVA, SPE/Tyr/GA and SPE/Tyr/HSA/GA, respectively. These biosensors were characterized by means of amperometry and EIS techniques. From amperometric evaluations, the apparent Michaelis-Menten constant, Km', of each biosensor was evaluated while the respective charge transfer resistance, Rct, was assessed from impedance measurements. It was found that the SPE/Tyr/GA had the smallest Km' (57 ± 7) µM and Rct values. This electrode also displayed both the lowest detection and quantification limits for catechol quantification. Using the SPE/Tyr/GA, the Trolox Equivalent Antioxidant Capacity (TEAC) was determined from infusions prepared with "mirto" (Salvia microphylla), "hHierba dulce" (Lippia dulcis) and "salve real" (Lippia alba), medicinal plants commonly used in Mexico.

  5. THE KINETICS OF THE REACTIONS CATALYZED BY AN ENZYMATIC PREPARATION PRODUCED BY A BACILLUS LICHENIFORMIS STRAIN

    Directory of Open Access Journals (Sweden)

    MONICA DRAGOMIRESCU

    2007-05-01

    Full Text Available Robust immobilization techniques that preserve the activity of biomolecules have manypotential applications. In recent years, a number of new bioimobilisation methods in solgel-derived materials were reported. The interactions between the biomolecule and theinorganic material determine the degree to which the biomolecule retains its nativeproperties. The newer technological developments in the field of immobilizedbiocatalysts can offer the possibility of a wider and more economical exploitation ofbiocatalysts in biological applications, food and feed industry, medicine, and in thedevelopment of bioprocess monitoring devices, like the biosensors.The aim of this study was to obtain immobilized enzymatic preparations by methodswhich affect enzyme conformations and kinetic parameters as less as possible. Weimmobilized the enzymatic preparation with protease activity produced by a Bacilluslicheniformis B 40 local strain by physical bonding on ceramics and entrapment into solgel-derived glasses obtained from tetraethyl orthosilicate (TEOS, deposited in thin layeron a ceramic support (entrapment/deposition. Both physically adsorbed andentrapped/deposited enzymes follow Michaelis-Menten kinetics, similar with the solubleenzyme. In the case of immobilized enzymes, the apparent Michaelis constant, Km, wasgreater than that of the native one, as it was expected. The kinetic parameters indicatethat the enzymatic preparations adsorbed on ceramic support and entrapped/depositedshow less affinity for the substrate, Km being 1.3 and 2.1 times higher than that of thenative enzyme, respectively. The maximum velocity increased also by 3.5 and 7.9 timesrespectively, compared with the free counterpart (according to Lineweaver-Burklinearization.

  6. Fractionation and Characterization of Tannin Acyl Hydrolase from Aspergillus niger

    Directory of Open Access Journals (Sweden)

    YUNITA ARIAN SANI ANWAR

    2009-09-01

    Full Text Available We previously produced tannin acyl hydrolase (tannase from Aspergillus niger isolated from cacao pod. In the present study the enzyme was subjected to fractionation by ammonium sulphate followed by dialysis process. The saturation level of ammonium sulphate used was 30-80% where the best enzyme activity was obtained at the saturation level of 60%. Compared to that of crude enzyme, specific activity of tannase after dialysis was four folds. Characterization results showed that optimum activity was at 35-50 oC and pH 6. Tannase was activated by K+ and Na+ at concentration of 0.01 and 0.05 M respectively. Mg2+ was found activate tannase only at 0.01 M. Addition of metal ions like Zn2+, Cu2+, Ca2+, Mn2+ and Fe2+ inhibited the enzyme activity. Kinetics analysis of various substrates tested showed that the Km value of tannic acid and gallotannin was 0.401 and 6.611 mM respectively. Vmax value of tannic acid was 10.804 U/ml and of gallotannin was 12.406 U/ml. Based on Michaelis-Menten constant (Km, the tannase obtained in the present study was more active in hydrolysing depside bonds rather than ester bonds.

  7. Fractionation and Characterization of Tannin Acyl Hydrolase from Aspergillus niger

    Directory of Open Access Journals (Sweden)

    YUNITA ARIAN SANI ANWAR

    2009-09-01

    Full Text Available We previously produced tannin acyl hydrolase (tannase from Aspergillus niger isolated from cacao pod. In the present study the enzyme was subjected to fractionation by ammonium sulphate followed by dialysis process. The saturation level of ammonium sulphate used was 30–80% where the best enzyme activity was obtained at the saturation level of 60%. Compared to that of crude enzyme, specific activity of tannase after dialysis was four folds. Characterization results showed that optimum activity was at 35–50 °C and pH 6. Tannase was activated by K+ and Na+ at concentration of 0.01 and 0.05 M respectively. Mg2+ was found activate tannase only at 0.01 M. Addition of metal ions like Zn2+, Cu2+, Ca2+, Mn2+ and Fe2+ inhibited the enzyme activity. Kinetics analysis of various substrates tested showed that the Km value of tannic acid and gallotannin was 0.401 and 6.611 mM respectively. Vmax value of tannic acid was 10.804 U/ml and of gallotannin was 12.406 U/ml. Based on Michaelis-Menten constant (Km, the tannase obtained in the present study was more active in hydrolysing depside bonds rather than ester bonds.

  8. 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.

  9. 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.

  10. Direct electrochemistry of glucose oxidase and glucose biosensing on a hydroxyl fullerenes modified glassy carbon electrode.

    Science.gov (United States)

    Gao, Yun-Fei; Yang, Tian; Yang, Xiao-Lu; Zhang, Yu-Shuai; Xiao, Bao-Lin; Hong, Jun; Sheibani, Nader; Ghourchian, Hedayatollah; Hong, Tao; Moosavi-Movahedi, Ali Akbar

    2014-10-15

    Direct electrochemistry of glucose oxidase (GOD) was achieved when GOD-hydroxyl fullerenes (HFs) nano-complex was immobilized on a glassy carbon (GC) electrode and protected with a chitosan (Chit) membrane. The ultraviolet-visible absorption spectrometry (UV-vis), transmission electron microscopy (TEM), and circular dichroism spectropolarimeter (CD) methods were utilized for additional characterization of the GOD, GOD-HFs and Chit/GOD-HFs. Chit/HFs may preserve the secondary structure and catalytic properties of GOD. The cyclic voltammograms (CVs) of the modified GC electrode showed a pair of well-defined quasi-reversible redox peaks with the formal potential (E°') of 353 ± 2 mV versus Ag/AgCl at a scan rate of 0.05 V/s. The heterogeneous electron transfer constant (ks) was calculated to be 2.7 ± 0.2s(-1). The modified electrode response to glucose was linear in the concentrations ranging from 0.05 to 1.0mM, with a detection limit of 5 ± 1 μM. The apparent Michaelis-Menten constant (Km(app)) was 694 ± 8 μM. Thus, the modified electrode could be applied as a third generation biosensor for glucose with high sensitivity, selectivity and low detection limit. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Direct electron transfer of glucose oxidase and biosensing for glucose based on PDDA-capped gold nanoparticle modified graphene/multi-walled carbon nanotubes electrode.

    Science.gov (United States)

    Yu, Yanyan; Chen, Zuanguang; He, Sijing; Zhang, Beibei; Li, Xinchun; Yao, Meicun

    2014-02-15

    In this work, poly (diallyldimethylammonium chloride) (PDDA)-capped gold nanoparticles (AuNPs) functionalized graphene (G)/multi-walled carbon nanotubes (MWCNTs) nanocomposites were fabricated. Based on the electrostatic attraction, the G/MWCNTs hybrid material can be decorated with AuNPs uniformly and densely. The new hierarchical nanostructure can provide a larger surface area and a more favorable microenvironment for electron transfer. The AuNPs/G/MWCNTs nanocomposite was used as a novel immobilization platform for glucose oxidase (GOD). Direct electron transfer (DET) was achieved between GOD and the electrode. Field emission scanning electron microscopy (FESEM), UV-vis spectroscopy and cyclic voltammetry (CV) were used to characterize the electrochemical biosensor. The glucose biosensor fabricated based on GOD electrode modified with AuNPs/G/MWCNTs demonstrated satisfactory analytical performance with high sensitivity (29.72mAM(-1)cm(-2)) and low limit of detection (4.8 µM). The heterogeneous electron transfer rate constant (ΚS) and the apparent Michaelis-Menten constant (Km) of GOD were calculated to be 11.18s(-1) and 2.09 mM, respectively. With satisfactory selectivity, reproducibility, and stability, the nanostructure we proposed offered an alternative for electrode fabricating and glucose biosensing. © 2013 Elsevier B.V. All rights reserved.

  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. Radiochromatographic assay of N-acyl-phosphatidylethanolamine-specific phospholipase D activity.

    Science.gov (United States)

    Fezza, Filomena; Gasperi, Valeria; Mazzei, Cinzia; Maccarrone, Mauro

    2005-04-01

    A radiochromatographic method has been set up to assay the activity of N-acyl-phosphatidylethanolamine-specific phospholipase D (NAPE-PLD), based on reversed-phase high-performance liquid chromatography (HPLC) and online scintillation counting. The anandamide (N-arachidonoylethanolamine, AEA), product released by NAPE-PLD from the N-arachidonoyl-phosphatidylethanolamine (NArPE) substrate, was separated using a C18 column eluted with methanol-water-acetic acid and was quantified with an external standard method. Baseline separation of AEA and NArPE was completed in less than 15 min, with a detection limit of 0.5 fmol AEA at a signal-to-noise ratio of 4:1. The sensitivity and accuracy of the radiochromatographic procedure allowed detection and characterization of NAPE-PLD activity in very tiny tissue samples or in samples where the enzymatic activity is very low. With this method, we could determine the kinetic constants (i.e., apparent Michaelis-Menten constant (Km) of 40.0+/-5.6 microM and maximum velocity (Vmax) of 22.2+/-3.5 pmol/min per milligram protein toward NArPE) and the distribution of NAPE-PLD activity in brain areas and peripheral tissues of mouse. In addition, we could collect unprecedented evidence that compounds widely used in studies of the endocannabinoid system (e.g., AEA and congeners, receptor a(nta)gonists and inhibitors of AEA degradation) can also affect NAPE-PLD activity.

  14. Uptake, accumulation and metabolic response of ferricyanide in weeping willows.

    Science.gov (United States)

    Yu, Xiao-Zhang; Gu, Ji-Dong

    2009-01-01

    The remediation potential and metabolic responses of plants to ferricyanide were investigated using pre-rooted weeping willows (Salix babylonica L.) grown hydroponically in growth chambers and treated with potassium ferricyanide. Positive responses were observed for the plants exposed to cyanide recovered in plant biomass was constant in all treatments, indicating that transport is a major limiting step for the uptake of ferricyanide by plants. The majority of the ferricyanide taken up from the growth media was possibly assimilated during transport through plants. The velocity of the removal processes can be described by Michaelis-Menten kinetics, and the half-saturation constant (K(M)) and the maximum removal capacity (v(max)) were estimated to be 228.1 mg CN L(-1) and 36.43 mg CN kg(-1) d(-1), respectively, using non-linear regression methods. These results suggest that weeping willows can take up, transport and assimilate ferricyanide; and phytoremediation is an option for cleaning up the environmental sites contaminated with cyanide complexes.

  15. Some Investigations on Protease Enzyme Production Kinetics Using Bacillus licheniformis BBRC 100053 and Effects of Inhibitors on Protease Activity

    Directory of Open Access Journals (Sweden)

    Zahra Ghobadi Nejad

    2014-01-01

    Full Text Available Due to great commercial application of protease, it is necessary to study kinetic characterization of this enzyme in order to improve design of enzymatic reactors. In this study, mathematical modeling of protease enzyme production kinetics which is derived from Bacillus licheniformis BBRC 100053 was studied (at 37°C, pH 10 after 73 h in stationary phase, and 150 rpm. The aim of the present paper was to determine the best kinetic model and kinetic parameters for production of protease and calculating Ki (inhibition constant of different inhibitors to find the most effective one. The kinetic parameters Km (Michaelis-Menten constant and Vm (maximum rate were calculated 0.626 mM and 0.0523 mM/min. According to the experimental results, using DFP (diisopropyl fluorophosphate and PMSF (phenylmethanesulfonyl fluoride as inhibitors almost 50% of the enzyme activity could be inhibited when their concentrations were 0.525 and 0.541 mM, respectively. Ki for DFP and PMSF were 0.46 and 0.56 mM, respectively. Kinetic analysis showed that the Lineweaver-Burk model was the best fitting model for protease production kinetics DFP was more effective than PMSF and both of them should be covered in the group of noncompetitive inhibitors.

  16. Amyloglucosidase enzymatic reactivity inside lipid vesicles

    Directory of Open Access Journals (Sweden)

    Kim Jin-Woo

    2007-10-01

    Full Text Available Abstract Efficient functioning of enzymes inside liposomes would open new avenues for applications in biocatalysis and bioanalytical tools. In this study, the entrapment of amyloglucosidase (AMG (EC 3.2.1.3 from Aspergillus niger into dipalmitoylphosphatidylcholine (DPPC multilamellar vesicles (MLVs and large unilamellar vesicles (LUVs was investigated. Negative-stain, freeze-fracture, and cryo-transmission electron microscopy images verified vesicle formation in the presence of AMG. Vesicles with entrapped AMG were isolated from the solution by centrifugation, and vesicle lamellarity was identified using fluorescence laser confocal microscopy. The kinetics of starch hydrolysis by AMG was modeled for two different systems, free enzyme in aqueous solution and entrapped enzyme within vesicles in aqueous suspension. For the free enzyme system, intrinsic kinetics were described by a Michaelis-Menten kinetic model with product inhibition. The kinetic constants, Vmax and Km, were determined by initial velocity measurements, and Ki was obtained by fitting the model to experimental data of glucose concentration-time curves. Predicted concentration-time curves using these kinetic constants were in good agreement with experimental measurements. In the case of the vesicles, the time-dependence of product (glucose formation was experimentally determined and simulated by considering the kinetic behavior of the enzyme and the permeation of substrate into the vesicle. Experimental results demonstrated that entrapped enzymes were much more stable than free enyzme. The entrapped enzyme could be recycled with retention of 60% activity after 3 cycles. These methodologies can be useful in evaluating other liposomal catalysis operations.

  17. Constant physics and characteristics of fundamental constant

    International Nuclear Information System (INIS)

    Tarrach, R.

    1998-01-01

    We present some evidence which supports a surprising physical interpretation of the fundamental constants. First, we relate two of them through the renormalization group. This leaves as many fundamental constants as base units. Second, we introduce and a dimensional system of units without fundamental constants. Third, and most important, we find, while interpreting the units of the a dimensional system, that is all cases accessible to experimentation the fundamental constants indicate either discretization at small values or boundedness at large values of the corresponding physical quantity. (Author) 12 refs

  18. Cosmological Hubble constant and nuclear Hubble constant

    International Nuclear Information System (INIS)

    Horbuniev, Amelia; Besliu, Calin; Jipa, Alexandru

    2005-01-01

    The evolution of the Universe after the Big Bang and the evolution of the dense and highly excited nuclear matter formed by relativistic nuclear collisions are investigated and compared. Values of the Hubble constants for cosmological and nuclear processes are obtained. For nucleus-nucleus collisions at high energies the nuclear Hubble constant is obtained in the frame of different models involving the hydrodynamic flow of the nuclear matter. Significant difference in the values of the two Hubble constant - cosmological and nuclear - is observed

  19. Foot Temperatures and Toe Blood Flow during a 12 km Winter Hike and Guard Duty

    National Research Council Canada - National Science Library

    Mekjavic, Igor B; Kocjan, Nina; Vrhovec, Miro; Golja, Petra; House, Carol; Eiken, Ola

    2005-01-01

    .... During the 3-week study, the trails were covered with snow. Peripheral vasodilatation, presumably as a result of the elevated core temperature, maintained average skin temperature constant during the 12 km hike, and increased toe temperature...

  20. Effects of 3G cell phone exposure on the structure and function of the human cytochrome P450 reductase.

    Science.gov (United States)

    Tanvir, Shazia; Thuróczy, György; Selmaoui, Brahim; Silva Pires Antonietti, Viviane; Sonnet, Pascal; Arnaud-Cormos, Delia; Lévêque, Philippe; Pulvin, Sylviane; de Seze, René

    2016-10-01

    Cell phones increase exposure to radiofrequency (RF) electromagnetic fields (EMFs). Whether EMFs exert specific effects on biological systems remains debatable. This study investigated the effect of cell phone exposure on the structure and function of human NADPH-cytochrome P450 reductase (CPR). CPR plays a key role in the electron transfer to cytochrome P450, which takes part in a wide range of oxidative metabolic reactions in various organisms from microbes to humans. Human CPR was exposed for 60min to 1966-MHz RF inside a transverse electromagnetic cell (TEM-cell) placed in an incubator. The specific absorption rate (SAR) was 5W·kg(-1). Conformation changes have been detected through fluorescent spectroscopy of flavin and tryptophan residues, and investigated through circular dichroism, dynamic light scattering and microelectrophoresis. These showed that CPR was narrowed. By using cytochrome C reductase activity to assess the electron flux through the CPR, the Michaelis Menten constant (Km) and the maximum initial velocity (Vmax) decreased by 22% as compared with controls. This change was due to small changes in the tertiary and secondary structures of the protein at 37°C. The relevance of these findings to an actual RF exposure scenario demands further biochemical and in-vivo confirmation. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase

    Directory of Open Access Journals (Sweden)

    M Ahmed

    2012-01-01

    Full Text Available This study analyses venom from the elapid krait snake Bungarus sindanus, which contains a high level of acetylcholinesterase (AChE activity. The enzyme showed optimum activity at alkaline pH (8.5 and 45ºC. Krait venom AChE was inhibited by substrate. Inhibition was significantly reduced by using a high ionic strength buffer; low ionic strength buffer (10 mM PO4 pH 7.5 inhibited the enzyme by 1. 5mM AcSCh, while high ionic strength buffer (62 mM PO4 pH 7.5 inhibited it by 1 mM AcSCh. Venom acetylcholinesterase was also found to be thermally stable at 45ºC; it only lost 5% of its activity after incubation at 45ºC for 40 minutes. The Michaelis-Menten constant (Km for acetylthiocholine iodide hydrolysis was found to be 0.068 mM. Krait venom acetylcholinesterase was also inhibited by ZnCl2, CdCl2, and HgCl2 in a concentrationdependent manner. Due to the elevated levels of AChE with high catalytic activity and because it is more stable than any other sources, Bungarus sindanus venom is highly valuable for biochemical studies of this enzyme.

  2. 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.

  3. A highly efficient microfluidic nano biochip based on nanostructured nickel oxide.

    Science.gov (United States)

    Ali, Md Azahar; Solanki, Pratima R; Patel, Manoj K; Dhayani, Hemant; Agrawal, Ved Varun; John, Renu; Malhotra, Bansi D

    2013-04-07

    We present results of the studies relating to fabrication of a microfluidic biosensor chip based on nickel oxide nanorods (NRs-NiO) that is capable of directly measuring the concentration of total cholesterol in human blood through electrochemical detection. Using this chip we demonstrate, with high reliability and in a time efficient manner, the detection of cholesterol present in buffer solutions at clinically relevant concentrations. The microfluidic channel has been fabricated onto a nickel oxide nanorod-based electrode co-immobilized with cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) that serves as the working electrode. Bare indium tin oxide served as the counter electrode. A Ag/AgCl wire introduced to the outlet of the microchannel acts as a reference electrode. The fabricated NiO nanorod-based electrode has been characterized using X-ray diffraction, Raman spectroscopy, HR-TEM, FT-IR, UV-visible spectroscopy and electrochemical techniques. The presented NRs-NiO based microfluidic sensor exhibits linearity in the range of 1.5-10.3 mM, a high sensitivity of 0.12 mA mM(-1) cm(-2) and a low value of 0.16 mM of the Michaelis-Menten constant (Km).

  4. Enhancing Activity and Stability of Uricase from Lactobacillus plantarum by Zeolite immobilization

    Science.gov (United States)

    Iswantini, D.; Nurhidayat, N.; Sarah

    2017-03-01

    Lactobacillus plantarum has been known be able to produce uricase for uric acid biosensor. Durability and stability of L. plantarum in generating uricase enzyme was low. Hence, we tried to enhance its durability and stability by immobilizing it onto activated 250 mg zeolite at room temperature using 100 μL L.plantarum suspension and 2.87 mM uric acid, while Michaelis-Menten constant (KM) and Vmax were obtained at 6.7431 mM and 0.9171 µA consecutively, and the linearity range was 0.1-3.3 mM (R2 = 0.9667). Limit of detection (LOD) and limit of quantification (LOQ) value of the measurement were 0.4827 mM and 1.6092 mM respectively. Biosensor stability treatment was carried out in two different treatments, using the same electrode and using disposable electrode. The disposable electrode stability showed better result based on repeated measurements, but stability was still need improvement.

  5. Increase of a Calcium Independent Transglutaminase Activity in the Erythrocyte during the Infection with Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Wasserman Moisés

    1999-01-01

    Full Text Available We have studied the activity of a calcium dependent transglutaminase (EC 2.3.2.13 during the growth of the parasite Plasmodium falciparum inside the infected human erythrocyte. There is only one detectable transglutaminase in the two-cell-system, and its origin is erythrocytic. No activity was detected in preparations of the parasite devoid of erythrocyte cytoplasm. The Michaelis Menten constants (Km of the enzyme for the substrates N'N'dimethylcaseine and putrescine were undistinguishable whether the cell extracts used in their determination were obtained from normal or from infected red cells. The total activity of transglutaminase in stringently synchronized cultures, measured at 0.5mM Ca2+, decreased with the maturation of the parasite. However, a fraction which became irreversibly activated and independent of calcium concentration was detected. The proportion of this fraction grew with maturation; it represented only 20% of the activity in 20 hr-old-trophozoites while in 48-hr-schizonts it was more than 85% of the total activity. The activation of this fraction of transglutaminase did not depend on an increase in the erythrocyte cytoplasmic calcium, since most of the calcium was shown to be located in the parasite.

  6. Regulation of brain aromatase activity in rats

    International Nuclear Information System (INIS)

    Roselli, C.E.; Ellinwood, W.E.; Resko, J.A.

    1984-01-01

    The distribution and regulation of aromatase activity in the adult rat brain with a sensitive in vitro assay that measures the amount of 3 H 2 O formed during the conversion of [1 beta- 3 H]androstenedione to estrone. The rate of aromatase activity in the hypothalamus-preoptic area (HPOA) was linear with time up to 1 h, and with tissue concentrations up to 5 mgeq/200 microliters incubation mixture. The enzyme demonstrated a pH optimum of 7.4 and an apparent Michaelis-Menten constant (Km) of 0.04 microns. The greatest amount of aromatase activity was found in amygdala and HPOA from intact male rats. The hippocampus, midbrain tegmentum, cerebral cortex, cerebellum, and anterior pituitary all contained negligible enzymatic activity. Castration produced a significant decrease in aromatase activity in the HPOA, but not in the amygdala or cerebral cortex. The HPOAs of male rats contained significantly greater aromatase activity than the HPOAs of female rats. In females, this enzyme activity did not change during the estrous cycle or after ovariectomy. Administration of testosterone to gonadectomized male and female rats significantly enhanced HPOA aromatase activities to levels approximating those found in HPOA from intact males. Therefore, the results suggest that testosterone, or one of its metabolites, is a major steroidal regulator of HPOA aromatase activity in rats

  7. 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.

  8. Immobilization of glucose oxidase using CoFe2O4/SiO2 nanoparticles as carrier

    Science.gov (United States)

    Wang, Hai; Huang, Jun; Wang, Chao; Li, Dapeng; Ding, Liyun; Han, Yun

    2011-04-01

    Aminated-CoFe2O4/SiO2 magnetic nanoparticles (NPs) were prepared from primary silica particles using modified StÖber method. Glucose oxidase (GOD) was immobilized on CoFe2O4/SiO2 NPs via cross-linking with glutaraldehyde (GA). The optimal immobilization condition was achieved with 1% (v/v) GA, cross-linking time of 3 h, solution pH of 7.0 and 0.4 mg GOD (in 3.0 mg carrier). The immobilized GOD showed maximal catalytic activity at pH 6.5 and 40 °C. After immobilization, the GOD exhibited improved thermal, storage and operation stability. The immobilized GOD still maintained 80% of its initial activity after the incubation at 50 °C for 25 min, whereas free enzyme had only 20% of initial activity after the same incubation. After kept at 4 °C for 28 days, the immobilized and free enzyme retained 87% and 40% of initial activity, respectively. The immobilized GOD maintained approximately 57% of initial activity after reused 7 times. The KM (Michaelis-Menten constant) values for immobilized GOD and free GOD were 14.6 mM and 27.1 mM, respectively.

  9. Electrodeposition of gold-platinum alloy nanoparticles on ionic liquid-chitosan composite film and its application in fabricating an amperometric cholesterol biosensor.

    Science.gov (United States)

    Safavi, Afsaneh; Farjami, Fatemeh

    2011-01-15

    An electrodeposition method was applied to form gold-platinum (AuPt) alloy nanoparticles on the glassy carbon electrode (GCE) modified with a mixture of an ionic liquid (IL) and chitosan (Ch) (AuPt-Ch-IL/GCE). AuPt nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. AuPt-Ch-IL/GCE electrocatalyzed the reduction of H(2)O(2) and thus was suitable for the preparation of biosensors. Cholesterol oxidase (ChOx) was then, immobilized on the surface of the electrode by cross-linking ChOx and chitosan through addition of glutaraldehyde (ChOx/AuPt-Ch-IL/GCE). The fabricated biosensor exhibited two wide linear ranges of responses to cholesterol in the concentration ranges of 0.05-6.2 mM and 6.2-11.2 mM. The sensitivity of the biosensor was 90.7 μA mM(-1) cm(-2) and the limit of detection was 10 μM of cholesterol. The response time was less than 7 s. The Michaelis-Menten constant (K(m)) was found as 0.24 mM. The effect of the addition of 1 mM ascorbic acid and glucose was tested on the amperometric response of 0.5 mM cholesterol and no change in response current of cholesterol was observed. Copyright © 2010 Elsevier B.V. All rights reserved.

  10. Amperometric cholesterol biosensor based on the direct electrochemistry of cholesterol oxidase and catalase on a graphene/ionic liquid-modified glassy carbon electrode.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Khodadadian, Mehdi

    2014-03-15

    Cholesterol oxidase (ChOx) and catalase (CAT) were co-immobilized on a graphene/ionic liquid-modified glassy carbon electrode (GR-IL/GCE) to develop a highly sensitive amperometric cholesterol biosensor. The H2O2 generated during the enzymatic reaction of ChOx with cholesterol could be reduced electrocatalytically by immobilized CAT to obtain a sensitive amperometric response to cholesterol. The direct electron transfer between enzymes and electrode surface was investigated by cyclic voltammetry. Both enzymes showed well-defined redox peaks with quasi-reversible behaviors. An excellent sensitivity of 4.163 mA mM(-1)cm(-2), a response time less than 6s, and a linear range of 0.25-215 μM (R(2)>0.99) have been observed for cholesterol determination using the proposed biosensor. The apparent Michaelis-Menten constant (KM(app)) was calculated to be 2.32 mM. The bienzymatic cholesterol biosensor showed good reproducibility (RSDsascorbic acid and uric acid. The CAT/ChOx/GR-IL/GCE showed excellent analytical performance for the determination of free cholesterol in human serum samples. © 2013 Elsevier B.V. All rights reserved.

  11. 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.

  12. FORMATION CONSTANTS AND THERMODYNAMIC ...

    African Journals Online (AJOL)

    KEY WORDS: Metal complexes, Schiff base ligand, Formation constant, DFT calculation ... best values for the formation constants of the proposed equilibrium model by .... to its positive charge distribution and the ligand deformation geometry.

  13. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

  14. The role of CYP2D6 in primary and secondary oxidative metabolism of dextromethorphan: in vitro studies using human liver microsomes.

    Science.gov (United States)

    Kerry, N L; Somogyi, A A; Bochner, F; Mikus, G

    1994-01-01

    1. The enzyme kinetics of dextromethorphan O-demethylation in liver microsomes from three extensive metabolisers (EM) with respect to CYP2D6 indicated high (Km1 2.2-9.4 microM) and low (Km2 55.5-307.3 microM) affinity sites whereas microsomes from two poor metabolisers (PM) indicated a single site (Km 560 and 157 microM). Similar differences were shown for 3-methoxymorphinan O-demethylation to 3-hydroxymorphinan (Km 6.9-9.6 microM in EM subjects; Km 307 and 213 microM in PM subjects). 2. Dextromethorphan O-demethylation was inhibited competitively by quinidine (Ki 0.1 microM), rac-perhexiline (Ki 0.4 microM), dextropropoxyphene (Ki 6 microM), rac-methadone (Ki 8 microM), and 3-methoxymorphinan (Ki 15 microM). These compounds were also potent inhibitors of 3-methoxymorphinan O-demethylation with IC50 values ranging from 0.02-12 microM. Anti-LKM1 serum inhibited both dextromethorphan and 3-methoxymorphinan O-demethylations in a titre-dependent manner. 3. The Michaelis-Menten constant for dextromethorphan N-demethylation to 3-methoxymorphinan (Km 632-977 microM) and dextrorphan N-demethylation to 3-hydroxymorphinan (Km 1571-4286 microM) did not differ between EM and PM microsomes. These N-demethylation reactions were not inhibited by quinidine and rac-methadone or LKM1 antibodies. 4. Dextromethorphan and 3-methoxymorphinan are metabolised by the same P450 isoform, CYP2D6, whereas the N-demethylation reactions are not carried out by CYP2D6. PMID:7826826

  15. Sea Surface Temperature (14 KM North America)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Product shows local sea surface temperatures (degrees C). It is a composite gridded-image derived from 8-km resolution SST Observations. It is generated every 48...

  16. G1SST, 1km blended SST

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A daily, global Sea Surface Temperature (SST) data set is produced at 1-km (also known as ultra-high resolution) by the JPL ROMS (Regional Ocean Modeling System)...

  17. Climate Prediction Center IR 4km Dataset

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CPC IR 4km dataset was created from all available individual geostationary satellite data which have been merged to form nearly seamless global (60N-60S) IR...

  18. MODIS/Aqua Clouds 5-Min L2 Swath 1km and 5km V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS/Aqua Clouds 5-Min L2 Swath 1km and 5km (MYD06_L2) product consists of cloud optical and physical parameters. These parameters are derived using remotely...

  19. Beyond the Hubble Constant

    Science.gov (United States)

    1995-08-01

    about the distances to galaxies and thereby about the expansion rate of the Universe. A simple way to determine the distance to a remote galaxy is by measuring its redshift, calculate its velocity from the redshift and divide this by the Hubble constant, H0. For instance, the measured redshift of the parent galaxy of SN 1995K (0.478) yields a velocity of 116,000 km/sec, somewhat more than one-third of the speed of light (300,000 km/sec). From the universal expansion rate, described by the Hubble constant (H0 = 20 km/sec per million lightyears as found by some studies), this velocity would indicate a distance to the supernova and its parent galaxy of about 5,800 million lightyears. The explosion of the supernova would thus have taken place 5,800 million years ago, i.e. about 1,000 million years before the solar system was formed. However, such a simple calculation works only for relatively ``nearby'' objects, perhaps out to some hundred million lightyears. When we look much further into space, we also look far back in time and it is not excluded that the universal expansion rate, i.e. the Hubble constant, may have been different at earlier epochs. This means that unless we know the change of the Hubble constant with time, we cannot determine reliable distances of distant galaxies from their measured redshifts and velocities. At the same time, knowledge about such change or lack of the same will provide unique information about the time elapsed since the Universe began to expand (the ``Big Bang''), that is, the age of the Universe and also its ultimate fate. The Deceleration Parameter q0 Cosmologists are therefore eager to determine not only the current expansion rate (i.e., the Hubble constant, H0) but also its possible change with time (known as the deceleration parameter, q0). Although a highly accurate value of H0 has still not become available, increasing attention is now given to the observational determination of the second parameter, cf. also the Appendix at the

  20. The Fine Structure Constant

    Indian Academy of Sciences (India)

    IAS Admin

    The article discusses the importance of the fine structure constant in quantum mechanics, along with the brief history of how it emerged. Al- though Sommerfelds idea of elliptical orbits has been replaced by wave mechanics, the fine struc- ture constant he introduced has remained as an important parameter in the field of ...

  1. Cosmological constants and variations

    International Nuclear Information System (INIS)

    Barrow, John D

    2005-01-01

    We review properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that is consistent with time-variation in the fine structure 'constant' since a redshift of 3.5. The behaviour of a simple class of varying alpha cosmologies is outlined in the light of all the observational constraints. We also discuss some of the consequences of varying 'constants' for oscillating universes and show by means of exact solutions that they appear to evolve monotonically in time even though the scale factor of the universe oscillates

  2. The cosmological constant problem

    International Nuclear Information System (INIS)

    Dolgov, A.D.

    1989-05-01

    A review of the cosmological term problem is presented. Baby universe model and the compensating field model are discussed. The importance of more accurate data on the Hubble constant and the Universe age is stressed. 18 refs

  3. Why to Integrate KM into everyday practices?

    International Nuclear Information System (INIS)

    Chavez Flores, A.T.

    2014-01-01

    Researchers have argued that one process to achieve a succesful KM initiative is the creation of a culture that values the transfer and creation of knowledge. Therefore, it’s neccesary for organizations to set up mechanisms by which new ideas may be shared in order to produce innovative changes

  4. Solutions for 80 km DWDM systems

    DEFF Research Database (Denmark)

    Dochhan, Annika; Griesser, Helmut; Eiselt, Nicklas

    2016-01-01

    Currently discussed solutions for 80 km DWDM transmission targeting inter-data center connections at 100G and 400G line rates are reviewed. PDM-64QAM, PAM4, and discrete multi-tone transmission (DMT) are investigated, while the focus lies on directly detected solutions. For DMT, the vestigial...

  5. On Improving 4-km Mesoscale Model Simulations

    Science.gov (United States)

    Deng, Aijun; Stauffer, David R.

    2006-03-01

    A previous study showed that use of analysis-nudging four-dimensional data assimilation (FDDA) and improved physics in the fifth-generation Pennsylvania State University National Center for Atmospheric Research Mesoscale Model (MM5) produced the best overall performance on a 12-km-domain simulation, based on the 18 19 September 1983 Cross-Appalachian Tracer Experiment (CAPTEX) case. However, reducing the simulated grid length to 4 km had detrimental effects. The primary cause was likely the explicit representation of convection accompanying a cold-frontal system. Because no convective parameterization scheme (CPS) was used, the convective updrafts were forced on coarser-than-realistic scales, and the rainfall and the atmospheric response to the convection were too strong. The evaporative cooling and downdrafts were too vigorous, causing widespread disruption of the low-level winds and spurious advection of the simulated tracer. In this study, a series of experiments was designed to address this general problem involving 4-km model precipitation and gridpoint storms and associated model sensitivities to the use of FDDA, planetary boundary layer (PBL) turbulence physics, grid-explicit microphysics, a CPS, and enhanced horizontal diffusion. Some of the conclusions include the following: 1) Enhanced parameterized vertical mixing in the turbulent kinetic energy (TKE) turbulence scheme has shown marked improvements in the simulated fields. 2) Use of a CPS on the 4-km grid improved the precipitation and low-level wind results. 3) Use of the Hong and Pan Medium-Range Forecast PBL scheme showed larger model errors within the PBL and a clear tendency to predict much deeper PBL heights than the TKE scheme. 4) Combining observation-nudging FDDA with a CPS produced the best overall simulations. 5) Finer horizontal resolution does not always produce better simulations, especially in convectively unstable environments, and a new CPS suitable for 4-km resolution is needed. 6

  6. 5 km de autopista al mes

    Directory of Open Access Journals (Sweden)

    Editorial, Equipo

    1972-02-01

    Full Text Available This is one of the most important civil engineering projects of its kind currently under construction in the country. It consists of 93 km of motor road, with four traffic lanes, and it includes many ancillary works, using prefabricated units, multilevel crossings and overpasses of varying lengths, some of them 600 m long. The large scale use of prefabricated elements and of very modern machinery will make it possible to complete the project several months ahead of schedule.Esta obra, que puede contarse entre las más importantes del país, comprende 93 km de autopista con cuatro circulaciones, numerosas obras de fábrica —prefabricadas—, intersecciones a distinto nivel y pasos elevados con longitudes varias, algunos de 600 metros. La prefabricación masiva y el empleo de una modernísima maquinaria permitió terminar la obra varios meses antes del plazo previsto.

  7. PERANCANGAN SISTEM PERPIPAAN KM. NUSANTARA (PIPING SYSTEM

    Directory of Open Access Journals (Sweden)

    Aulia Windyandari

    2013-10-01

    Full Text Available Sistem perpipaan merupakan sistem komplek yang didesain seefektif dan  seefisien mungkin untuk memenuhi kebutuhan dalam kapal ,crew ,muatan dan menjaga keamanan kapal baik saat berlayar ataupun berlabuh. Secara umum sistem pipa dapat diartikan sebagai  bagian utama suatu sistem yang menghubungkan titik dimana fluida di simpan ke titik pengeluaran semua pipa baik untuk memindahkan tenaga atau pemompaan harus dipertimbangkan secara teliti karena keamanan dari sebuah kapal akan tergantung pada susunan perpipaaan seperti halnya pada perlengkapan kapal lainnya Paper ini akan menguraikan tahap-tahap yang harus dilakukan serta pertimbangan-pertimbangan matematis yang diambil  oleh seorang ship engineer  dalam merancang suatu system perpipaan pada kapal KM. Nusantara. Hasil akhir dari paper ini adalah sebuah desain system perpipaan pada pada sebuah kapal,yaitu KM Nusantara, dengan mempertimbangkan system perpipaan yang paling efektif dalam pengoperasiannya.

  8. Effects of multi-frequency power ultrasound on the enzymolysis of corn gluten meal: Kinetics and thermodynamics study.

    Science.gov (United States)

    Jin, Jian; Ma, Haile; Qu, Wenjuan; Wang, Kai; Zhou, Cunshan; He, Ronghai; Luo, Lin; Owusu, John

    2015-11-01

    The effects of multi-frequency power ultrasound (MPU) pretreatment on the kinetics and thermodynamics of corn gluten meal (CGM) were investigated in this research. The apparent constant (KM), apparent break-down rate constant (kA), reaction rate constants (k), energy of activation (Ea), enthalpy of activation (ΔH), entropy of activation (ΔS) and Gibbs free energy of activation (ΔG) were determined by means of the Michaelis-Menten equation, first-order kinetics model, Arrhenius equation and transition state theory, respectively. The results showed that MPU pretreatment can accelerate the enzymolysis of CGM under different enzymolysis conditions, viz. substrate concentration, enzyme concentration, pH, and temperature. Kinetics analysis revealed that MPU pretreatment decreased the KM value by 26.1% and increased the kA value by 7.3%, indicating ultrasound pretreatment increased the affinity between enzyme and substrate. In addition, the values of k for ultrasound pretreatment were increased by 84.8%, 41.9%, 28.9%, and 18.8% at the temperature of 293, 303, 313 and 323 K, respectively. For the thermodynamic parameters, ultrasound decreased Ea, ΔH and ΔS by 23.0%, 24.3% and 25.3%, respectively, but ultrasound had little change in ΔG value in the temperature range of 293-323 K. In conclusion, MPU pretreatment could remarkably enhance the enzymolysis of CGM, and this method can be applied to protein proteolysis industry to produce peptides. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Radiographic constant exposure technique

    DEFF Research Database (Denmark)

    Domanus, Joseph Czeslaw

    1985-01-01

    The constant exposure technique has been applied to assess various industrial radiographic systems. Different X-ray films and radiographic papers of two producers were compared. Special attention was given to fast film and paper used with fluorometallic screens. Radiographic image quality...... was tested by the use of ISO wire IQI's and ASTM penetrameters used on Al and Fe test plates. Relative speed and reduction of kilovoltage obtained with the constant exposure technique were calculated. The advantages of fast radiographic systems are pointed out...

  10. Erythrocyte glucose-6-phosphate dehydrogenase from Brazilian opossum Didelphis marsupialis

    Directory of Open Access Journals (Sweden)

    Barretto O.C. de O.

    2006-01-01

    Full Text Available In a comparative study of erythrocyte metabolism of vertebrates, the specific activity of glucose-6-phosphate dehydrogenase (G6PD of the Brazilian opossum Didelphis marsupialis in a hemolysate was shown to be high, 207 ± 38 IU g-1 Hb-1 min-1 at 37ºC, compared to the human erythrocyte activity of 12 ± 2 IU g-1 Hb-1 min-1 at 37ºC. The apparent high specific activity of the mixture led us to investigate the physicochemical properties of the opossum enzyme. We report that reduced glutathione (GSH in the erythrocytes was only 50% higher than in human erythrocytes, a value lower than expected from the high G6PD activity since GSH is maintained in a reduced state by G6PD activity. The molecular mass, determined by G-200 Sephadex column chromatography at pH 8.0, was 265 kDa, which is essentially the same as that of human G6PD (260 kDa. The Michaelis-Menten constants (Km: 55 µM for glucose-6-phosphate and nicotinamide adenine dinucleotide phosphate (Km: 3.3 µM were similar to those of the human enzyme (Km: 50-70 and Km: 2.9-4.4, respectively. A 450-fold purification of the opossum enzyme was achieved and the specific activity of the purified enzyme, 90 IU/mg protein, was actually lower than the 150 IU/mg protein observed for human G6PD. We conclude that G6PD after purification from the hemolysate of D. marsupialis does not have a high specific activity. Thus, it is quite probable that the red cell hyperactivity reported may be explained by increased synthesis of G6PD molecules per unit of hemoglobin or to reduced inactivation in the RBC hemolysate.

  11. On the cosmical constant

    International Nuclear Information System (INIS)

    Chandra, R.

    1977-01-01

    On the grounds of the two correspondence limits, the Newtonian limit and the special theory limit of Einstein field equations, a modification of the cosmical constant has been proposed which gives realistic results in the case of a homogeneous universe. Also, according to this modification an explanation for the negative pressure in the steady-state model of the universe has been given. (author)

  12. Cosmological constant problem

    International Nuclear Information System (INIS)

    Weinberg, S.

    1989-01-01

    Cosmological constant problem is discussed. History of the problem is briefly considered. Five different approaches to solution of the problem are described: supersymmetry, supergravity, superstring; anthropic approach; mechamism of lagrangian alignment; modification of gravitation theory and quantum cosmology. It is noted that approach, based on quantum cosmology is the most promising one

  13. The Yamabe constant

    International Nuclear Information System (INIS)

    O Murchadha, N.

    1991-01-01

    The set of riemannian three-metrics with positive Yamabe constant defines the space of independent data for the gravitational field. The boundary of this set is investigated, and it is shown that metrics close to the boundary satisfy the positive-energy theorem. (Author) 18 refs

  14. Metabolomics on integrated circuit

    OpenAIRE

    Cheah, Boon Chong; MacDonald, Alasdair I.; Barrett, Michael P.; Cumming, David R.S.

    2017-01-01

    We have demonstrated a chip-based diagnostics tool for the quantification of metabolites, using specific enzymes, to study enzyme kinetics and calculate the Michaelis-Menten constant. An array of 256×256 ion-sensitive field effect transistors (ISFETs) fabricated in a complementary metal oxide semiconductor (CMOS) process is used for this prototype. We have used hexokinase enzyme reaction on the ISFET CMOS chip with glucose concentration in the physiological range of 0.05 mM – 231 mM and succe...

  15. Covalent immobilization of invertase on PAMAM-dendrimer modified superparamagnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Uzun, K.; Cevik, E.; Senel, M.; Soezeri, H.; Baykal, A.; Abasiyanik, M. F.; Toprak, M. S.

    2010-01-01

    In this study, polyamidoamine (PAMAM) dendrimer was synthesized on the surface of superparamagnetite nanoparticles to enhance invertase immobilization. The amount of immobilized enzyme on the surface-hyperbranched magnetite nanoparticle was up to 2.5 times (i.e., 250%) as much as that of magnetite nanoparticle modified with only amino silane. Maximum reaction rate (V max ) and Michaelis-Menten constant (K m ) were determined for the free and immobilized enzymes. Various characteristics of immobilized invertase such as; the temperature activity, thermal stability, operational stability, and storage stability were evaluated and results revealed that stability of the enzyme is improved upon immobilization.

  16. Production in constant evolution

    International Nuclear Information System (INIS)

    Lozano, T.

    2009-01-01

    The Cofrentes Nuclear Power Plant now has 25 years of operation behind it: a quarter century adding value and demonstrating the reasons why it is one of the most important energy producing facilities in the Spanish power market. Particularly noteworthy is the enterprising spirit of the plant, which has strived to continuously improve with the large number of modernization projects that it has undertaken over the past 25 years. The plant has constantly evolved thanks to the amount of investments made to improve safety and reliability and the perseverance to stay technologically up to date. Efficiency, training and teamwork have been key to the success of the plant over these 25 years of constant change and progress. (Author)

  17. Is the sun constant

    International Nuclear Information System (INIS)

    Blake, J.B.; Dearborn, D.S.P.

    1979-01-01

    Small fluctuations in the solar constant can occur on timescales much shorter than the Kelvin time. Changes in the ability of convection to transmit energy through the superadiabatic and transition regions of the convection zone cause structure adjustments which can occur on a time scale of days. The bulk of the convection zone reacts to maintain hydrostatic equilibrium (though not thermal equilibrium) and causes a luminosity change. While small radius variations will occur, most of the change will be seen in temperature

  18. Stabilized power constant alimentation

    International Nuclear Information System (INIS)

    Roussel, L.

    1968-06-01

    The study and realization of a stabilized power alimentation variable from 5 to 100 watts are described. In order to realize a constant power drift of Lithium compensated diodes, we have searched a 1 per cent precision of regulation and a response time minus than 1 sec. Recent components like Hall multiplicator and integrated amplifiers give this possibility and it is easy to use permutable circuits. (author) [fr

  19. Universe of constant

    Science.gov (United States)

    Yongquan, Han

    2016-10-01

    The ideal gas state equation is not applicable to ordinary gas, it should be applied to the Electromagnetic ``gas'' that is applied to the radiation, the radiation should be the ultimate state of matter changes or initial state, the universe is filled with radiation. That is, the ideal gas equation of state is suitable for the Singular point and the universe. Maybe someone consider that, there is no vessel can accommodate radiation, it is because the Ordinary container is too small to accommodate, if the radius of your container is the distance that Light through an hour, would you still think it can't accommodates radiation? Modern scientific determinate that the radius of the universe now is about 1027 m, assuming that the universe is a sphere whose volume is approximately: V = 4.19 × 1081 cubic meters, the temperature radiation of the universe (cosmic microwave background radiation temperature of the universe, should be the closest the average temperature of the universe) T = 3.15k, radiation pressure P = 5 × 10-6 N / m 2, according to the law of ideal gas state equation, PV / T = constant = 6 × 1075, the value of this constant is the universe, The singular point should also equal to the constant Author: hanyongquan

  20. Connecting Fundamental Constants

    International Nuclear Information System (INIS)

    Di Mario, D.

    2008-01-01

    A model for a black hole electron is built from three basic constants only: h, c and G. The result is a description of the electron with its mass and charge. The nature of this black hole seems to fit the properties of the Planck particle and new relationships among basic constants are possible. The time dilation factor in a black hole associated with a variable gravitational field would appear to us as a charge; on the other hand the Planck time is acting as a time gap drastically limiting what we are able to measure and its dimension will appear in some quantities. This is why the Planck time is numerically very close to the gravitational/electric force ratio in an electron: its difference, disregarding a π√(2) factor, is only 0.2%. This is not a coincidence, it is always the same particle and the small difference is between a rotating and a non-rotating particle. The determination of its rotational speed yields accurate numbers for many quantities, including the fine structure constant and the electron magnetic moment

  1. 10 km running performance predicted by a multiple linear regression model with allometrically adjusted variables.

    Science.gov (United States)

    Abad, Cesar C C; Barros, Ronaldo V; Bertuzzi, Romulo; Gagliardi, João F L; Lima-Silva, Adriano E; Lambert, Mike I; Pires, Flavio O

    2016-06-01

    The aim of this study was to verify the power of VO 2max , peak treadmill running velocity (PTV), and running economy (RE), unadjusted or allometrically adjusted, in predicting 10 km running performance. Eighteen male endurance runners performed: 1) an incremental test to exhaustion to determine VO 2max and PTV; 2) a constant submaximal run at 12 km·h -1 on an outdoor track for RE determination; and 3) a 10 km running race. Unadjusted (VO 2max , PTV and RE) and adjusted variables (VO 2max 0.72 , PTV 0.72 and RE 0.60 ) were investigated through independent multiple regression models to predict 10 km running race time. There were no significant correlations between 10 km running time and either the adjusted or unadjusted VO 2max . Significant correlations (p 0.84 and power > 0.88. The allometrically adjusted predictive model was composed of PTV 0.72 and RE 0.60 and explained 83% of the variance in 10 km running time with a standard error of the estimate (SEE) of 1.5 min. The unadjusted model composed of a single PVT accounted for 72% of the variance in 10 km running time (SEE of 1.9 min). Both regression models provided powerful estimates of 10 km running time; however, the unadjusted PTV may provide an uncomplicated estimation.

  2. The inconstant solar constant

    International Nuclear Information System (INIS)

    Willson, R.C.; Hudson, H.

    1984-01-01

    The Active Cavity Radiometer Irradiance Monitor (ACRIM) of the Solar Maximum Mission satellite measures the radiant power emitted by the sun in the direction of the earth and has worked flawlessly since 1980. The main motivation for ACRIM's use to measure the solar constant is the determination of the extent to which this quantity's variations affect earth weather and climate. Data from the solar minimum of 1986-1987 is eagerly anticipated, with a view to the possible presence of a solar cycle variation in addition to that caused directly by sunspots

  3. 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.

  4. Toward 10-km mesh global climate simulations

    Science.gov (United States)

    Ohfuchi, W.; Enomoto, T.; Takaya, K.; Yoshioka, M. K.

    2002-12-01

    An atmospheric general circulation model (AGCM) that runs very efficiently on the Earth Simulator (ES) was developed. The ES is a gigantic vector-parallel computer with the peak performance of 40 Tflops. The AGCM, named AFES (AGCM for ES), was based on the version 5.4.02 of an AGCM developed jointly by the Center for Climate System Research, the University of Tokyo and the Japanese National Institute for Environmental Sciences. The AFES was, however, totally rewritten in FORTRAN90 and MPI while the original AGCM was written in FORTRAN77 and not capable of parallel computing. The AFES achieved 26 Tflops (about 65 % of the peak performance of the ES) at resolution of T1279L96 (10-km horizontal resolution and 500-m vertical resolution in middle troposphere to lower stratosphere). Some results of 10- to 20-day global simulations will be presented. At this moment, only short-term simulations are possible due to data storage limitation. As ten tera flops computing is achieved, peta byte data storage are necessary to conduct climate-type simulations at this super-high resolution global simulations. Some possibilities for future research topics in global super-high resolution climate simulations will be discussed. Some target topics are mesoscale structures and self-organization of the Baiu-Meiyu front over Japan, cyclogenecsis over the North Pacific and typhoons around the Japan area. Also improvement in local precipitation with increasing horizontal resolution will be demonstrated.

  5. Teleportation of entanglement over 143 km.

    Science.gov (United States)

    Herbst, Thomas; Scheidl, Thomas; Fink, Matthias; Handsteiner, Johannes; Wittmann, Bernhard; Ursin, Rupert; Zeilinger, Anton

    2015-11-17

    As a direct consequence of the no-cloning theorem, the deterministic amplification as in classical communication is impossible for unknown quantum states. This calls for more advanced techniques in a future global quantum network, e.g., for cloud quantum computing. A unique solution is the teleportation of an entangled state, i.e., entanglement swapping, representing the central resource to relay entanglement between distant nodes. Together with entanglement purification and a quantum memory it constitutes a so-called quantum repeater. Since the aforementioned building blocks have been individually demonstrated in laboratory setups only, the applicability of the required technology in real-world scenarios remained to be proven. Here we present a free-space entanglement-swapping experiment between the Canary Islands of La Palma and Tenerife, verifying the presence of quantum entanglement between two previously independent photons separated by 143 km. We obtained an expectation value for the entanglement-witness operator, more than 6 SDs beyond the classical limit. By consecutive generation of the two required photon pairs and space-like separation of the relevant measurement events, we also showed the feasibility of the swapping protocol in a long-distance scenario, where the independence of the nodes is highly demanded. Because our results already allow for efficient implementation of entanglement purification, we anticipate our research to lay the ground for a fully fledged quantum repeater over a realistic high-loss and even turbulent quantum channel.

  6. The diffusion of radioactive gases in the meso-scale (20 km-400 km)

    International Nuclear Information System (INIS)

    Wippermann, F.

    1974-01-01

    The term ''Mesoscale'' refers to distances between 20 km and 400 km from the source; in defining this range, the structure of atmospheric turbulence is taken into account. To arrive at an evaluation of diffusion in the mesoscale, quantitative methods from the microscale (source distance 400 km) are extrapolated into the mesoscale. In the first case a table is given to read off the minimum factor by which the concentration is reduced in the mesoscale as the source distance increases to obtain the diffusion for the worst possible case, the existence of a mixing-layer topped by a temperature inversion, was assumed. For this it was essential, first of all, to determine the source distance xsub(D) beyond which the diffusing gases are completely mixed within the mixing-layer of thickness D. To make allowance for all possible thicknesses of this mixing-layer, a measurement carried out at ground level at only 10 km from the source can be used to calculate the correct concentrations in the mixing-layer; the dilution factors will then be related to this value. Possible ways of an improved incorporation of certain factors in the diffusion estimate, such as the topography of the earth's surface, the roughness of terrain, the vertical profiles of wind and exchange coefficients and the effects of non-stability are given in the last section

  7. Characterization of β-glucosidase from Aspergillus terreus and its application in the hydrolysis of soybean isoflavones.

    Science.gov (United States)

    Yan, Feng-Ying; Xia, Wei; Zhang, Xiao-Xu; Chen, Sha; Nie, Xin-Zheng; Qian, Li-Chun

    2016-06-01

    An extracellular β-glucosidase produced by Aspergillus terreus was identified, purified, characterized and was tested for the hydrolysis of soybean isoflavone. Matrix-assisted laser desorption/ionization with tandem time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS) revealed the protein to be a member of the glycosyl hydrolase family 3 with an apparent molecular mass of about 120 kDa. The purified β-glucosidase showed optimal activity at pH 5.0 and 65 °C and was very stable at 50 °C. Moreover, the enzyme exhibited good stability over pH 3.0-8.0 and possessed high tolerance towards pepsin and trypsin. The kinetic parameters Km (apparent Michaelis-Menten constant) and Vmax (maximal reaction velocity) for p-nitrophenyl-β-D-glucopyranoside (pNPG) were 1.73 mmol/L and 42.37 U/mg, respectively. The Km and Vmax for cellobiose were 4.11 mmol/L and 5.7 U/mg, respectively. The enzyme efficiently converted isoflavone glycosides to aglycones, with a hydrolysis rate of 95.8% for daidzin, 86.7% for genistin, and 72.1% for glycitin. Meanwhile, the productivities were 1.14 mmol/(L·h) for daidzein, 0.72 mmol/(L·h) for genistein, and 0.19 mmol/(L·h) for glycitein. This is the first report on the application of A. terreus β-glucosidase for converting isoflavone glycosides to their aglycones in soybean products.

  8. New fluorescent bile acids: synthesis, chemical characterization, and disastereoselective uptake by Caco-2 cells of 3-deoxy 3-NBD-amino deoxycholic and ursodeoxycholic acid.

    Science.gov (United States)

    Májer, Ferenc; Salomon, Johanna J; Sharma, Ruchika; Etzbach, Simona V; Najib, Mohd Nadzri Mohd; Keaveny, Ray; Long, Aideen; Wang, Jun; Ehrhardt, Carsten; Gilmer, John F

    2012-03-01

    Deoxycholic acid (DCA), a secondary bile acid (BA), and ursodeoxycholic acid (UDCA), a tertiary BA, cause opposing effects in vivo and in cell suspensions. Fluorescent analogues of DCA and UDCA could help investigate important questions about their cellular interactions and distribution. We have prepared a set of isomeric 3α- and 3β-amino analogues of UDCA and DCA and derivatised these with the discrete fluorophore, 4-nitrobenzo-2-oxa-1,3-diazol (NBD), forming the corresponding four fluorescent adducts. These absorb in the range 465-470 nm and fluoresce at approx. 535 nm. In order to determine the ability of the new fluorescent bile acids to mimic the parents, their uptake was studied using monolayers of Caco-2 cells, which are known to express multiple proteins of the organic anion-transporting peptide (OATP) subfamily of transporters. Cellular uptake was monitored over time at 4 and 37°C to distinguish between passive and active transport. All four BA analogues were taken up but in a strikingly stereo- and structure-specific manner, suggesting highly discriminatory interactions with transporter protein(s). The α-analogues of DCA and to a lesser extent UDCA were actively transported, whereas the β-analogues were not. The active transport process was saturable, with Michaelis-Menten constants for 3α-NBD DCA (5) being K(m)=42.27±12.98 μM and V(max)=2.8 ± 0.4 nmol/(mg protein*min) and for 3α-NBD UDCA (3) K(m)=28.20 ± 7.45 μM and V(max)=1.8 ± 0.2 nmol/(mg protein*min). These fluorescent bile acids are promising agents for investigating questions of bile acid biology and for detection of bile acids and related organic anion transport processes. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. 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.

  10. Digestive enzyme activities and gastrointestinal fermentation in wood-eating catfishes.

    Science.gov (United States)

    German, Donovan P; Bittong, Rosalie A

    2009-11-01

    To determine what capabilities wood-eating and detritivorous catfishes have for the digestion of refractory polysaccharides with the aid of an endosymbiotic microbial community, the pH, redox potentials, concentrations of short-chain fatty acids (SCFAs), and the activity levels of 14 digestive enzymes were measured along the gastrointestinal (GI) tracts of three wood-eating taxa (Panaque cf. nigrolineatus "Marañon", Panaque nocturnus, and Hypostomus pyrineusi) and one detritivorous species (Pterygoplichthys disjunctivus) from the family Loricariidae. Negative redox potentials (-600 mV) were observed in the intestinal fluids of the fish, suggesting that fermentative digestion was possible. However, SCFA concentrations were low (<3 mM in any intestinal region), indicating that little GI fermentation occurs in the fishes' GI tracts. Cellulase and xylanase activities were low (<0.03 U g(-1)), and generally decreased distally in the intestine, whereas amylolytic and laminarinase activities were five and two orders of magnitude greater, respectively, than cellulase and xylanase activities, suggesting that the fish more readily digest soluble polysaccharides. Furthermore, the Michaelis-Menten constants (K(m)) of the fishes' beta-glucosidase and N-acetyl-beta-D-glucosaminidase enzymes were significantly lower than the K(m) values of microbial enzymes ingested with their food, further suggesting that the fish efficiently digest soluble components of their detrital diet rather than refractory polysaccharides. Coupled with rapid gut transit and poor cellulose digestibility, the wood-eating catfishes appear to be detritivores reliant on endogenous digestive mechanisms, as are other loricariid catfishes. This stands in contrast to truly "xylivorous" taxa (e.g., beavers, termites), which are reliant on an endosymbiotic community of microorganisms to digest refractory polysaccharides.

  11. KARAKTERISTIK KM. ZAISAN STAR AKIBAT PERUBAHAN MUATAN

    Directory of Open Access Journals (Sweden)

    Samuel Samuel

    2014-02-01

    Full Text Available KM. Zaisan Star yang semula merupakan kapal general cargo dimodifikasi menjadi kapal pengangkut kendaraan (vehicle carrier dengan penambahan geladak pada ruang muat dan diatas geladak utama. Penelitian ini bertujuan mengetahui nilai stabilitas dan kekuatan memanjang kapal dari 32 simulasi kondisi karena pengaruh pengisian geladak muat dan kondisi pelayaran kapal. Perhitungan dan analisa pada penelitian ini dilakukan dengan metode pendekatan rumus stabilitas dan kekuatan memanjang kapal yang terintegrasi pada perangkat lunak pekapalan yang mengacu standar IMO dan Rules BKI. Hasil analisa stabilitas menunjukkan nilai GZ terendah pada kondisi XXXI dengan 1,103 m sedangkan kriteria minimumnya 0,200 m. Nilai GM terendah pada kondisi XXXII dengan 1,160 m, sedangkan nilai minimumnya 0,150 m. Pada analisa kekuatan memanjang diperoleh nilai tegangan geladak kondisi air tenang 0,009 N/mm2, sagging 0,013 N/mm2 dan hogging 3,40 N/mm2 serta tegangan alas kondisi air tenang 0,020 N/mm2, sagging 0,029 N/mm2 dan hogging 7,825 N/mm2, nilai tersebut tidak melebihi nilai tegangan ijin kapal 188,815 N/mm2. Perhitungan modulus penampang menunjukkan nilai modulus penampang geladak 831,990 m3 dan alas 1913,974 m3, nilai tersebut memenuhi nilai modulus minimum kapal 0,1824 m3. Perhitungan momen inersia menunjukkan nilai momen inersia sebesar 2899,540 m4, nilai ini memenuhi nilai minimum momen inersia kapal 0,4103 m4.

  12. Modified fractal iron oxide magnetic nanostructure: A novel and high performance platform for redox protein immobilization, direct electrochemistry and bioelectrocatalysis application.

    Science.gov (United States)

    Bagheri, Hasan; Ranjbari, Elias; Amiri-Aref, Mohaddeseh; Hajian, Ali; Ardakani, Yalda Hosseinzadeh; Amidi, Salimeh

    2016-11-15

    A novel biosensing platform based on fractal-pattern of iron oxides magnetic nanostructures (FIOMNs) and mixed hemi/ad-micelle of sodium dodecyl sulfate (SDS) was designed for the magnetic immobilization of hemoglobin (Hb) at a screen printed carbon electrode (SPCE). The FIOMNs was successfully synthesized through hydrothermal approach and characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). In order to provide guidelines for the mixed hemi/ad-micelle formation, zeta-potential isotherms were investigated. The construction steps of the biosensor were evaluated by electrochemical impedance spectroscopy, cyclic voltammetry and Fourier transform infrared spectroscopy. Direct electron transfer of Hb incorporated into the biocomposite film was realized with a pair of quasi-reversible redox peak at the formal potential of -0.355V vs. Ag/AgCl attributing to heme Fe(III)/Fe(II) redox couple. The results suggested that synergistic functions regarding to the hyper-branched and multidirectional structure of FIOMNs and the dual interaction ability of mixed hemi/ad-micelle array of SDS molecules not only induce an effective electron transfer between the Hb and the underlying electrode (high heterogeneous electron transfer rate constant of 2.08s(-1)) but also provide powerful and special microenvironment for the adsorption of the redox proteins. Furthermore, the biosensor displayed an excellent performance to the electrocatalytic reduction of H2O2 with a detection limit of 0.48µM and Michaelis-Menten constant (Km) value of 44.2µM. The fabricated biosensor represented the features of sensitivity, disposable design, low sample volume, rapid and simple preparation step, and acceptable anti-interferences, which offer great perspectives for the screen-determination of H2O2 in real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Modulation of catechol estrogen synthesis by rat liver microsomes: effects of treatment with growth hormone or testosterone

    International Nuclear Information System (INIS)

    Quail, J.A.; Jellinck, P.H.

    1987-01-01

    The ability of GH from various mammalian species, administered to normal mature male rats by constant infusion, to decrease the hepatic 2-hydroxylation of estradiol (E2) to female levels, as measured by the release of 3 H 2 O from [2-3H]E2, was determined. Rat and human GH (hGH) showed the highest activity while ovine GH was inactive. PRL (0.6 IU/h X kg) administered together with hGH (0.02 IU/h X kg) did not antagonize the feminizing action of GH. Infusion of hGH into male rats decreased the affinity of estradiol 2-hydroxylase for its steroid substrate and altered the linear Lineweaver-Burk plot towards a nonlinear hyperbolic plot characteristic of the female. The apparent Michaelis-Menten constant (Km) for the reaction was 1.69 microM for males and 2.75 microM for testosterone-treated ovariectomized females. An equal mixture of liver microsomes from male and female rats gave kinetic values similar to those observed with males alone. Neonatal imprinting with androgen did not alter the magnitude of the response of female rats to treatment with testosterone and/or GH at maturity and the androgen effect could only be shown in ovariectomized animals. The results with rats of different endocrine status were corroborated by the kinetic data and by the pattern of metabolites obtained with [4- 14 C]E2 when examined by TLC and autoradiography. The hormonal control of estradiol 2-hydroxylase, the key enzyme in catechol estrogen formation, and the contribution of sex-specific multiple forms of the enzyme to this reaction are discussed

  14. Decreased uptake of 3H-serotonin and endogenous content of serotonin in blood platelets in hypertensive patients

    International Nuclear Information System (INIS)

    Kamal, L.A.; Le Quan-Bui, K.H.; Meyer, P.

    1984-01-01

    The uptake and content of serotonin in blood platelets were studied in patients with essential hypertension and in five families in which at least one member was hypertensive. Blood was obtained from male and female normotensive volunteers and hypertensive patients who were free of medication. Lineweaver-Burk plots of 3H-serotonin uptake from both control subjects and hypertensive patients were linear, which suggested simple Michaelis-Menten uptake kinetics. The maximal uptake velocity (Vmax) in hypertensive patients was significantly lower than in control subjects (control . 41.7 +/- 3.3 pmol/min/10(8) platelets, n . 17; hypertensive . 26.6 +/- 3.0 pmol/min/10(8) platelets, n . 16; p less than 0.005). The affinity constant (Km) was slightly but significantly lower in hypertensive patients (control . 0.70 +/- 0.08 microM; hypertensive . 0.46 +/- 0.08 microM; p less than 0.05). The serotonin content in blood platelets determined by high pressure liquid chromatography with electrochemical detection was significantly lower in hypertensive patients (control . 165.0 +/- 12.9 nmol/10(11) platelets, n . 29; hypertensive . 105.9 +/- 10.4 nmol/10(11) platelets, n . 27; p less than 0.001). In the five families investigated, the lowered serotonin content was observed in some normotensive members. The reduced number of carriers of serotonin uptake and the slight decrease in the affinity constant observed in platelets of patients with essential hypertension suggest that serotonin metabolism is altered in essential hypertension and that blood platelets may be a useful model in studying the serotonergic modifications at the molecular level

  15. Imidazoline derivative templated synthesis of broccoli-like Bi2S3 and its electrocatalysis towards the direct electrochemistry of hemoglobin.

    Science.gov (United States)

    Chen, Xiaoqian; Wang, Qingxiang; Wang, Liheng; Gao, Feng; Wang, Wei; Hu, Zhengshui

    2015-04-15

    A broccoli-like bismuth sulfide (bBi2S3) was synthesized via a solvothermal method using a self-made imidazoline derivative of 2-undecyl-1-dithioureido-ethyl-imidazoline as the soft template. The morphology and chemical constitution of the product were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). Electrochemical characterization experiments show that the bBi2S3 has the higher specific surface area and standard heterogeneous electron transfer rate constant than the rod-like Bi2S3 (rBi2S3). Hemoglobin (Hb) was then chosen as a protein model to investigate the electrocatalytic property of the synthesized bBi2S3. The results show that Hb entrapped in the composite film of chitosan and bBi2S3 displays an excellent direct electrochemistry, and retains its biocatalytic activity toward the electro-reduction of hydrogen peroxide. The current response in the amperometry shows a linear response to H2O2 concentrations in the range from 0.4 to 4.8µM with high sensitivity (444µAmM(-1)) and low detection limit (0.096µM). The Michaelis-Menten constant (KM(app)) of the fabricated bioelectrode for H2O2 was determined as low as 1µM. These results demonstrate that the synthesized bBi2S3 offers a new path for the immobilization of redox-active protein and the construction of the third-generation biosensors. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Exploring the Mediation Between KM Infrastructure Capabilities and Organisational Performance: The Penetration of Learning by KM Practices

    OpenAIRE

    Meng-Lin Shih; Shu-Hui Chuang; Chechen Liao

    2009-01-01

    Previous studies have examined the relationship between knowledge management (KM) infrastructure capabilities and organisational performance. However, most studies neglect the mediating effect of organisational learning by KM practices (OLKMP) in the relationship between KM infrastructure capabilities and organisational performance. This study uses the survey method to discuss the relationships governing KM infrastructure capabilities, OLKMP and organisational performance. Results of the anal...

  17. Microbial respiration and kinetics of extracellular enzymes activities through rhizosphere and detritusphere at agricultural site

    Science.gov (United States)

    Löppmann, Sebastian; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2014-05-01

    detritivore communities in the soil. The kinetics (Km and Vmax) of four extracellular hydrolytic enzymes responsible for C- and phosphorous-cycle (β-glucosidase, β-xylosidase, β-cellobiohydrolase and acid phosphatase), microbial biomass, basal respiration (BR) and substrate-induced respiration (SIR) were measured in rhizosphere, detritusphere and control from 0 - 10 and 10 - 20 cm. The metabolic quotient (qCO2) was calculated as specific indicator for efficiency of microbial substrate utilization. We observed clear differences in enzymes activities at low and high concentrations of substrate. At substrate saturation enzyme activity rates of were significantly higher in rooted plots compared to litter amended plots, whereas at lower concentration no treatment effect could be found. The BR, SIR and qCO2 values were significantly higher at 0 - 10 cm of the planted treatment compared to litter and control plots, revealing a significantly higher respiration at lower efficiency of microbial substrate utilization in the rhizosphere. The Michaelis-Menten constant (Km) decreased with depth, especially for β-glucosidase, acid phosphatase and β-xylosidase, indicating higher substrate affinity of microorganisms in deeper soil and therefore different enzyme systems functioning. The substrate affinity factor (Vmax/Km) increased 2-fold with depth for various enzymes, reflecting a switch of predominantly occurring microbial strategies. Vmax/Km ratio indicated relative domination of zymogenous microbial communities (r-strategists) in 0 - 10 cm depth as compared with 10 - 20 cm depth where the K-strategists dominated.

  18. Potential constants and centrifugal distortion constants of octahedral hexafluoride molecules

    Energy Technology Data Exchange (ETDEWEB)

    Manivannan, G [Government Thirumagal Mill' s Coll., Gudiyattam, Tamil Nadu (India)

    1981-04-01

    The kinetic constants method outlined by Thirugnanasambandham (1964) based on Wilson's (1955) group theory has been adapted in evaluating the potential constants for SF/sub 6/, SeF/sub 6/, WF/sub 6/, IrF/sub 6/, UF/sub 6/, NpF/sub 6/, and PuF/sub 6/ using the experimentally observed vibrational frequency data. These constants are used to calculate the centrifugal distortion constants for the first time.

  19. Arbuscular mycorrhiza and kinetic parameters of phosphorus absorption by bean plants Micorriza arbuscular e os parâmetros cinéticos de absorção de fósforo pelo feijoeiro

    Directory of Open Access Journals (Sweden)

    Adriana Parada Dias da Silveira

    2004-04-01

    Full Text Available The mechanisms that determine greater P absorption by mycorrhizal plants are still not completely clear, and are attributed, in part, to an increase in the number of absorption sites promoted by the hyphae, and/or to a greater affinity of the colonized hypha or root carriers to P. The effect of mycorrhizae formed by Glomus etunicatum on the kinetic parameters of P absorption by the roots and on P influx in bean plants of the IAC-Carioca cultivar was evaluated, in two distinct plant development periods: at the onset of flowering and at the pod-filling stage (35 and 50 days after sowing, respectively. A mixture of sand and silica (9:1 was utilized as substrate and irrigated with nutrient solution. The kinetics assay was performed by the method of 32P depletion from the solution (depletion curve, using intact plants. Mycorrhization promoted greater growth and P absorption by bean plants, which was more conspicuously observed at the pod-filling stage. Mycorrhizal plants showed higher values of maximum ion uptake rate (Vmax and net P influx at the flowering stage. Lower minimum ion concentration (Cmin and Michaelis-Menten constant (Km values were verified in mycorrhizal plants at the pod-filling stage. Mycorrhizal plants also presented higher net P influx per plant, in both stages. Cmin was the kinetic parameter more intimately related to P absorption, and a significant correlation was obtained between this parameter and shoot P content and accumulation in bean plants.Os mecanismos envolvidos na maior absorção de P pela planta micorrizada ainda não estão totalmente esclarecidos, atribuindo-se, em parte, ao aumento no número de sítios de absorção promovido pela hifa e/ou maior afinidade dos carregadores da hifa ou da raiz colonizada ao P. Avaliou-se o efeito da micorriza formada por Glomus etunicatum nos parâmetros cinéticos da absorção radicular de P e no influxo de P em feijoeiro, cultivar IAC-Carioca, em duas épocas do ciclo da planta

  20. Association constants of telluronium salts

    International Nuclear Information System (INIS)

    Kovach, N.A.; Rivkin, B.B.; Sadekov, T.D.; Shvajka, O.P.

    1996-01-01

    Association constants in acetonitrile of triphenyl telluronium salts, which are dilute electrolytes, are determined through the conductometry method. Satisfactory correlation dependence of constants of interion association and threshold molar electroconductivity on the Litvinenko-Popov constants for depositing groups is identified. 6 refs

  1. Anisotropic constant-roll inflation

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Asuka; Soda, Jiro [Kobe University, Department of Physics, Kobe (Japan)

    2018-01-15

    We study constant-roll inflation in the presence of a gauge field coupled to an inflaton. By imposing the constant anisotropy condition, we find new exact anisotropic constant-roll inflationary solutions which include anisotropic power-law inflation as a special case. We also numerically show that the new anisotropic solutions are attractors in the phase space. (orig.)

  2. Quintessence and the cosmological constant

    International Nuclear Information System (INIS)

    Doran, M.; Wetterich, C.

    2003-01-01

    Quintessence -- the energy density of a slowly evolving scalar field -- may constitute a dynamical form of the homogeneous dark energy in the universe. We review the basic idea in the light of the cosmological constant problem. Cosmological observations or a time variation of fundamental 'constants' can distinguish quintessence from a cosmological constant

  3. Comparison between constant methanol feed and on-line ...

    African Journals Online (AJOL)

    Two methanol feeding methods, namely constant methanol feed and on-line monitoring feed control by methanol sensor were investigated to improve the production of recombinant human growth hormone (rhGH) in high cell density cultivation of Pichia pastoris KM71 in 2 L bioreactor. The yeast utilized glycerol as a carbon ...

  4. ZnO nanowire-based glucose biosensors with different coupling agents

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Juneui [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Lim, Sangwoo, E-mail: swlim@yonsei.ac.kr [Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Fabrication of ZnO nanowire-based glucose biosensors using different coupling agents. Black-Right-Pointing-Pointer Highest sensitivity for (3-aminopropyl)methyldiethoxysilane-treated biosensor. Black-Right-Pointing-Pointer Larger amount of glucose oxidase and lower electron transfer resistance for (3-aminopropyl)methyldiethoxysilane-treated biosensor. - Abstract: ZnO-nanowire-based glucose biosensors were fabricated by immobilizing glucose oxidase (GOx) onto a linker attached to ZnO nanowires. Different coupling agents were used, namely (3-aminopropyl)trimethoxysilane (APTMS), (3-aminopropyl)triethoxysilane (APTES), and (3-aminopropyl)methyldiethoxysilane (APS), to increase the affinity of GOx binding to ZnO nanowires. The amount of GOx immobilized on the ZnO nanowires, the performance, sensitivity, and Michaelis-Menten constant of each biosensor, and the electron transfer resistance through the biosensor were all measured in order to investigate the effect of the coupling agent on the ZnO nanowire-based biosensor. Among the different biosensors, the APS-treated biosensor had the highest sensitivity (17.72 {mu}A cm{sup -2} mM{sup -1}) and the lowest Michaelis-Menten constant (1.37 mM). Since APS-treated ZnO nanowires showed the largest number of C-N groups and the lowest electron transfer resistance through the biosensor, we concluded that these properties were the key factors in the performance of APS-treated glucose biosensors.

  5. Modeling uptake kinetics of cadmium by field-grown lettuce

    Energy Technology Data Exchange (ETDEWEB)

    Chen Weiping [Department of Environmental Sciences, University of California, 900 University Avenue, Riverside, CA 92521 (United States)], E-mail: chenweip@yahoo.com.cn; Li Lianqing [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095 (China); Chang, Andrew C.; Wu Laosheng [Department of Environmental Sciences, University of California, 900 University Avenue, Riverside, CA 92521 (United States); Kwon, Soon-Ik [Agricultural Environmental and Ecology Division, National Institute of Agricultural Science and Technology, Suwon 441-707 (Korea, Republic of); Bottoms, Rick [Desert Research and Extension Center, 1004 East Holton Road, El Centro, CA 92243 (United States)

    2008-03-15

    Cadmium uptake by field grown Romaine lettuce treated with P-fertilizers of different Cd levels was investigated over an entire growing season. Results indicated that the rate of Cd uptake at a given time of the season can be satisfactorily described by the Michaelis-Menten kinetics, that is, plant uptake increases as the Cd concentration in soil solution increases, and it gradually approaches a saturation level. However, the rate constant of the Michaelis-Menten kinetics changes over the growing season. Under a given soil Cd level, the cadmium content in plant tissue decreases exponentially with time. To account for the dynamic nature of Cd uptake, a kinetic model integrating the time factor was developed to simulate Cd plant uptake over the growing season: C{sub Plant} = C{sub Solution} . PUF{sub max} . exp[-b . t], where C{sub Plant} and C{sub Solution} refer to the Cd content in plant tissue and soil solution, respectively, PUF{sub max} and b are kinetic constants. - A kinetic model was developed to evaluate the uptake of Cd under field conditions.

  6. Modeling uptake kinetics of cadmium by field-grown lettuce

    International Nuclear Information System (INIS)

    Chen Weiping; Li Lianqing; Chang, Andrew C.; Wu Laosheng; Kwon, Soon-Ik; Bottoms, Rick

    2008-01-01

    Cadmium uptake by field grown Romaine lettuce treated with P-fertilizers of different Cd levels was investigated over an entire growing season. Results indicated that the rate of Cd uptake at a given time of the season can be satisfactorily described by the Michaelis-Menten kinetics, that is, plant uptake increases as the Cd concentration in soil solution increases, and it gradually approaches a saturation level. However, the rate constant of the Michaelis-Menten kinetics changes over the growing season. Under a given soil Cd level, the cadmium content in plant tissue decreases exponentially with time. To account for the dynamic nature of Cd uptake, a kinetic model integrating the time factor was developed to simulate Cd plant uptake over the growing season: C Plant = C Solution . PUF max . exp[-b . t], where C Plant and C Solution refer to the Cd content in plant tissue and soil solution, respectively, PUF max and b are kinetic constants. - A kinetic model was developed to evaluate the uptake of Cd under field conditions

  7. Control of Acid Phosphatases Expression from Aspergillus niger by Soil Characteristics

    Directory of Open Access Journals (Sweden)

    Ely Nahas

    2015-10-01

    Full Text Available ABSTRACTThis work studied the acid phosphatase (APase activity from culture medium (extracellular, eAPase and mycelial extract (intracellular, iAPase ofAspergillus niger F111. The influence of fungus growth and phosphate concentration of the media on the synthesis and secretion of phosphatase was demonstrated. The effects of pH, substrate concentration and inorganic and organic compounds added to the reaction mixture on APase activity were also studied. Both enzymes were repressed by high concentrations of phosphate. Overexpression of iAPase in relation to eAPase was detected; iAPase activity was 46.1 times higher than eAPase. The maximal activity of eAPase was after 24h of fungus growth and for iAPase was after 96h. Optimal pH and substrate concentrations were 4.5 and 8.0 mM, respectively. Michaelis-Menten constant (Km for the hydrolysis of p-nitrophenyl phosphate was 0.57 mM with Vmax = 14,285.71 U mg-1 mycelium for the iAPase and 0.31 mM with V max = 147.06 U mg-1 mycelium for eAPase. Organic substances had little effect on acid phosphatases when compared with the salts. Both the APases were inhibited by 10 mM KH 2PO4 and 5 mM (NH42MoO4; eAPase was also inhibited by 1 mM CoCl2.

  8. Novel, reagentless, amperometric biosensor for uric acid based on a chemically modified screen-printed carbon electrode coated with cellulose acetate and uricase.

    Science.gov (United States)

    Gilmartin, M A; Hart, J P

    1994-05-01

    Amperometry in stirred solution has been used for the systematic evaluation of modified screen-printed carbon electrodes (SPCEs) with a view to developing a reagentless biosensor for uric acid. The developed system consists of a base cobalt phthalocyanine (CoPC) electrode tailored to the electrocatalytic oxidation of H2O2 by means of a cellulose acetate (CA)-uricase bilayer. Uricase was immobilized by drop-coating the enzyme onto the CA membrane covering the CoPC-SPCE. The device exploits the near-universal H2O2-generating propensity of oxidases, the permselectivity of the CA film towards H2O2 and the electrocatalytic oxidation of this product at the CoPC-SPCE. The electrochemical oxidation of the resulting Co+ species was used as the analytical signal, facilitating the application of a greatly reduced operating potential when compared with that required for direct oxidation of H2O2 at unmodified electrodes. The time required to achieve 95% of the steady-state current (t95i(ss)) was 44 s [relative standard deviation = 7.5% (n = 10)]. Amperometric calibrations were linear over the range from 13 x 10(-6) to 1 x 10(-3) mol dm-3, with the former representing the limit of detection. The CA membrane extended the linear range of the biosensor by over two orders of magnitude, when apparent Michaelis-Menten constants (Km') of immobilized and free enzymes are compared. This suggests that the process is diffusion-controlled and not governed by the kinetics of the enzyme. The precision of electrode fabrication was determined by cyclic voltammetry to be 4.9% (n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Covalent immobilization of α-amylase on magnetic particles as catalyst for hydrolysis of high-amylose starch.

    Science.gov (United States)

    Guo, Hui; Tang, Yi; Yu, Yang; Xue, Lu; Qian, Jun-Qing

    2016-06-01

    Enzyme immobilized on magnetic particles can be used as efficient recoverable biocatalysts under strong magnetic response. To enable re-use of enzyme, modified Fe3O4 particles were used as carrier to immobilize α-amylase in this paper. Firstly, the surface of Fe3O4 particles were coated with amino groups by direct using TEOS (tetraethoxysilane) followed by treatment with APTES (3-aminopropyltriethoxysilane) and then carboxylated by reacting it with succinic anhydride. In addition, the effect of the immobilization condition on enzyme activity recovery and immobilization efficiency were investigated. The results showed that the optimal immobilization occurred under following conditions: pH 5.5, 40°C, enzyme concentration of 20mgmL(-1), reaction time for 36h. Using immobilized α-amylase as biocatalyst, the optimum pH and temperature for hydrolysis were observed to be 6.5 and 60°C. The kinetics of hydrolysis reaction were studied using Michaelis-Menten equation. The affinity constant (Km) and maximum reaction rate (vmax) of magnetic particles immobilization α-amylase (MPIA) was 0.543mgmL(-1) and 1.321mgmin(-1) compared to those of 0.377mgmL(-1) and 6.859mgmin(-1) of free enzyme. After immobilization, enzymatic activity, storage stability, thermo-stability, and reusability of MPIA were found superior to those of the free one. MPIA maintained 86% enzyme activity after 30 days and maintained 78% enzyme activity after recycling six times. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Biosensing hydrogen peroxide utilizing carbon paste electrodes containing peroxidases naturally immobilized on coconut (Cocus nucifera L.) fibers.

    Science.gov (United States)

    Kozan, J V B; Silva, R P; Serrano, S H P; Lima, A W O; Angnes, L

    2007-05-22

    A novel unmediated hydrogen peroxide biosensor based on the incorporation of fibrous tissue of coconut fruit in carbon paste matrix is presented. Cyclic voltammetry and amperometry were utilized to characterize the main electrochemical parameters and the performance of this new biosensor under different preparation and operation conditions. The resulting H2O2-sensitive biosensors respond rapidly (7 s to attain 90% of the signal), was operated at -0.15 V, presented linear response between 2.0x10(-4) and 3.4x10(-3) mol L(-1), the detection limit was estimated as 4.0x10(-5) mol L(-1). Its operation potential was situated between -0.2 and 0.1 V and the best pH was determined as 5.2. Electrodes containing 5% (w/w) of coconut fiber presented the best signal and their lifetime was extended to 3 months. The apparent Michaelis-Menten constant KM(app) and Vmax were estimated to be 8.90 mmol L(-1) and 6.92 mmol L(-1) microA(-1), respectively. The results obtained for determination of hydrogen peroxide in four pharmaceutical products (antiseptic solution, contact lenses cleaning solution, hair coloring cream and antiseptic dental rinse solution) were in agreement with those obtained by the spectrophotometric method. An additional advantage of these biosensors is the capacity to measure hydrogen peroxide even in samples with relatively low pH. To demonstrate the enzymatic activity of the coconut tissue, a very simple way was created during this work. Coconut fibers were immersed in H2O2 solution between two glass slides. Sequential images were taken to show the rapid generation of O2, attesting the high activity of the enzymes.

  11. Catalytic properties of IgMs with amylolytic activity isolated from patients with multiple sclerosis.

    Science.gov (United States)

    Ivanen, Dina R; Kulminskaya, Anna A; Shabalin, Konstantin A; Isaeva-Ivanova, Luydmila V; Ershova, Nadezhda A; Saveliev, Andrew N; Nevinsky, Gregory A; Neustroev, Kirill N

    2004-08-01

    Recently, amylolytic activity was detected in IgMs isolated from the sera of the patients with multiple sclerosis. All purified samples of IgM were electrophoretically homogenous and did not contain any co-purified a-amylase and a-glucosidase activities, in accordance with a set of criteria developed for abzymes. The amylolytic activity of abzymes was studied in the hydrolysis of p-nitrophenyl a-D-maltooligosaccharides with different degrees of polymerization from 1 to 8 by TLC and reverse-phase HPLC techniques. All IgM samples isolated from 54 patients with clinically definite multiple sclerosis demonstrated hydrolytic activity towards the above artificial substrates. The Michaelis constant values (Km) in the hydrolysis of p-nitrophenyl a-D-maltoheptaoside were in the range of 10 p-nitrophenyl or p-nitrophenyl a-D-glucosides, thus indicating the presence of an a-D-glucosidase activity. For a number of the investigated samples, specific amylolytic activity increased depending on the length of substrates (from p-nitrophenyl maltopentaoside to p-nitrophenyl maltohexaoside); for other IgMs, the opposite dependence was observed. All IgMs studied did not exhibit any other glycoside hydrolase activities toward p-nitrophenyl glycoside substrates. Abzyme fractions from different donors demonstrated catalytic heterogeneity in Michaelis-Menten parameters and different modes of action in the hydrolysis of p-nitrophenyl maltooligosaccharides. Enzymatic properties of the IgMs tested varied from human a-amylases. All investigated abzyme samples did not show transglycosylating ability.

  12. Bilirubin glucuronidation revisited: proper assay conditions to estimate enzyme kinetics with recombinant UGT1A1.

    Science.gov (United States)

    Zhou, Jin; Tracy, Timothy S; Remmel, Rory P

    2010-11-01

    Bilirubin, an end product of heme catabolism, is primarily eliminated via glucuronic acid conjugation by UGT1A1. Impaired bilirubin conjugation, caused by inhibition of UGT1A1, can result in clinical consequences, including jaundice and kernicterus. Thus, evaluation of the ability of new drug candidates to inhibit UGT1A1-catalyzed bilirubin glucuronidation in vitro has become common practice. However, the instability of bilirubin and its glucuronides presents substantial technical challenges to conduct in vitro bilirubin glucuronidation assays. Furthermore, because bilirubin can be diglucuronidated through a sequential reaction, establishment of initial rate conditions can be problematic. To address these issues, a robust high-performance liquid chromatography assay to measure both bilirubin mono- and diglucuronide conjugates was developed, and the incubation conditions for bilirubin glucuronidation by human embryonic kidney 293-expressed UGT1A1 were carefully characterized. Our results indicated that bilirubin glucuronidation should be assessed at very low protein concentrations (0.05 mg/ml protein) and over a short incubation time (5 min) to assure initial rate conditions. Under these conditions, bilirubin total glucuronide formation exhibited a hyperbolic (Michaelis-Menten) kinetic profile with a K(m) of ∼0.2 μM. In addition, under these initial rate conditions, the relative proportions between the total monoglucuronide and the diglucuronide product were constant across the range of bilirubin concentration evaluated (0.05-2 μM), with the monoglucuronide being the predominant species (∼70%). In conclusion, establishment of appropriate incubation conditions (i.e., very low protein concentrations and short incubation times) is necessary to properly characterize the kinetics of bilirubin glucuronidation in a recombinant UGT1A1 system.

  13. Administration of progesterone after trauma and hemorrhagic shock prevents hepatocellular injury.

    Science.gov (United States)

    Kuebler, Joachim F; Yokoyama, Yukihiro; Jarrar, Doraid; Toth, Balazs; Rue, Loring W; Bland, Kirby I; Wang, Ping; Chaudry, Irshad H

    2003-07-01

    Administration of a single dose of progesterone following trauma and hemorrhage in progesterone-deficient rats would ameliorate the inflammatory response and hepatocellular damage. A university laboratory. Ovariectomized female Sprague-Dawley rats (250-350 g; Charles River Laboratories, Wilmington, Mass) underwent a 5-cm midline laparotomy (ie, induction of soft tissue trauma), were bled to a mean arterial blood pressure of 35 mm Hg for about 90 minutes, and then were resuscitated using Ringer lactate solution. Progesterone (25 mg/kg of body weight) or vehicle was administered subcutaneously at the end of resuscitation. In additional animals, Kupffer cells were isolated following trauma, hemorrhage, and resuscitation and treated in vitro with progesterone, lipopolysaccharide, or both. Six hours following resuscitation, plasma tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) levels and liver myeloperoxidase activity were determined. Hepatocellular function (maximum velocity of indocyanine green clearance [Vmax] and the efficiency of the active transport or Michaelis-Menten constant [Km]) and plasma levels of transaminases were measured 20 hours after resuscitation. Kupffer cell IL-6 and TNF-alpha production were assessed. Plasma levels of TNF-alpha, IL-6, aspartate aminotransferase, and alanine aminotransferase, as well as hepatic myeloperoxidase activity were increased, whereas indocyanine green clearance was depressed in vehicle-treated rats following trauma-hemorrhage. Animals treated with progesterone showed significantly reduced levels of the TNF-alpha, IL-6, and transaminases as well as reduced myeloperoxidase activity in the liver. Progesterone-treated animals showed increased Vmax and Kmax values for indocyanine green. In vitro treatment of Kupffer cells with progesterone decreased TNF-alpha production but did not affect the production of IL-6. Progesterone administration following trauma-hemorrhage ameliorates the proinflammatory response

  14. Choline transport via choline transporter-like protein 1 in conditionally immortalized rat syncytiotrophoblast cell lines TR-TBT.

    Science.gov (United States)

    Lee, N-Y; Choi, H-M; Kang, Y-S

    2009-04-01

    Choline is an essential nutrient for phospholipids and acetylcholine biosynthesis in normal development of fetus. In the present study, we investigated the functional characteristics of choline transport system and inhibitory effect of cationic drugs on choline transport in rat conditionally immortalized syncytiotrophoblast cell line (TR-TBT). Choline transport was weakly Na(+) dependent and significantly influenced by extracellular pH and by membrane depolarization. The transport process of choline is saturable with Michaelis-Menten constants (K(m)) of 68microM and 130microM in TR-TBT 18d-1 and TR-TBT 18d-2 respectively. Choline uptake in the cells was inhibited by unlabeled choline and hemicholinium-3 as well as various organic cations including guanidine, amiloride and acetylcholine. However, the prototypical organic cation tetraethylammonium and cimetidine showed very little inhibitory effect of choline uptake in TR-TBT cells. RT-PCR revealed that choline transporter-like protein 1 (CTL1) and organic cation transporter 2 (OCT2) are expressed in TR-TBT cells. The transport properties of choline in TR-TBT cells were similar or identical to that of CTL1 but not OCT2. CTL1 was also detected in human placenta. In addition, several cationic drugs such as diphenhydramine and verapamil competitively inhibited choline uptake in TR-TBT 18d-1 with K(i) of 115microM and 55microM, respectively. Our results suggest that choline transport system, which has intermediate affinity and weakly Na(+) dependent, in TR-TBT seems to occur through a CTL1 and this system may have relevance with the uptake of pharmacologically important organic cation drugs.

  15. Mixed hemi/ad-micelles coated magnetic nanoparticles for the entrapment of hemoglobin at the surface of a screen-printed carbon electrode and its direct electrochemistry and electrocatalysis.

    Science.gov (United States)

    Amiri-Aref, Mohaddeseh; Raoof, Jahan Bakhsh; Kiekens, Filip; De Wael, Karolien

    2015-12-15

    An efficient procedure for the physical entrapment of proteins within a biocompatible matrix and their immobilization on electrode surfaces is of utmost importance in the fabrication of biosensors. In this work, the magnetic entrapment of hemoglobin (Hb) at the surface of a screen-printed carbon electrode (SPCE), through mixed hemi/ad-micelles (MHAM) array of positively charged surfactant supported iron oxide magnetic nanoparticles (Mag-NPs), is reported. The Hb/MHAM@Mag-NPs biocomposite is captured at SPCE by a super magnet (Hb/MHAM@Mag-NPs/SPCE). To gain insight in the configuration of the mixed hemi/ad-micelles of CTAB at Mag-NPs, zeta-potential measurements were performed. The entrapment of Hb at MHAM@Mag-NPs was confirmed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FT-IR). Direct electron transfer of the Hb intercalated into the composite film showed a pair of well-defined quasi-reversible redox peak at formal potential of -0.255 V vs. Ag/AgCl corresponding to heme Fe(III)/Fe(II) redox couple. It shows that the MHAM@Mag-NPs composite could increase the adsorption ability for Hb, thus provides a facile direct electron transfer between the Hb and the substrate. The proposed biosensor showed excellent electrocatalytic activity to the H2O2 reduction in the wide concentration range from 5.0 to 300.0 µM obtained by amperometric measurement. The Michaelis-Menten constant (Km) value of Hb at the modified electrode is 55.4 µM, showing its high affinity. Magnetic entrapment offers a promising design for fast, convenient and effective immobilization of protein within a few minutes for determination of the target molecule in low sample volume at disposable cost-effective SPCE. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Determination of Unbound Partition Coefficient and in Vitro-in Vivo Extrapolation for SLC13A Transporter-Mediated Uptake.

    Science.gov (United States)

    Riccardi, Keith; Li, Zhenhong; Brown, Janice A; Gorgoglione, Matthew F; Niosi, Mark; Gosset, James; Huard, Kim; Erion, Derek M; Di, Li

    2016-10-01

    Unbound partition coefficient (Kpuu) is important to an understanding of the asymmetric free drug distribution of a compound between cells and medium in vitro, as well as between tissue and plasma in vivo, especially for transporter-mediated processes. Kpuu was determined for a set of compounds from the SLC13A family that are inhibitors and substrates of transporters in hepatocytes and transporter-transfected cell lines. Enantioselectivity was observed, with (R)-enantiomers achieving much higher Kpuu (>4) than the (S)-enantiomers (<1) in human hepatocytes and SLC13A5-transfected human embryonic 293 cells. The intracellular free drug concentration correlated directly with in vitro pharmacological activity rather than the nominal concentration in the assay because of the high Kpuu mediated by SLC13A5 transporter uptake. Delivery of the diacid PF-06649298 directly or via hydrolysis of the ethyl ester prodrug PF-06757303 resulted in quite different Kpuu values in human hepatocytes (Kpuu of 3 for diacid versus 59 for prodrug), which was successfully modeled on the basis of passive diffusion, active uptake, and conversion rate from ester to diacid using a compartmental model. Kpuu values changed with drug concentrations; lower values were observed at higher concentrations possibly owing to a saturation of transporters. Michaelis-Menten constant (Km) of SLC13A5 was estimated to be 24 μM for PF-06649298 in human hepatocytes. In vitro Kpuu obtained from rat suspension hepatocytes supplemented with 4% fatty acid free bovine serum albumin showed good correlation with in vivo Kpuu of liver-to-plasma, illustrating the potential of this approach to predict in vivo Kpuu from in vitro systems. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  17. Diferencias cinéticas de las plasminas de ocho especies mamíferas: activaciones y secuencias de los terminales-N

    Directory of Open Access Journals (Sweden)

    Omaira Cañás Bermúdez

    2013-12-01

    Full Text Available El artículo determina los parámetros cinéticos de las plasminas de ocho especies de mamíferos y sus terminales-N. Los ocho plasminógenos fueron purificados por los mismos métodos (cromatografías de afinidad e intercambio iónico, y activados con urocinasa, partiendo de una concentración común y su cinética valorada según las coordenadas de Lineweaver- Burk. Para esto se utilizó la cinética enzimática de Michaelis Menten, ampliamente usada en el estudio de enzimas. Todos los plasminógenos mostraron una pureza superior al 95 % y una banda de 92 kDa en la electroforesis, al comparar con el estándar de peso molecular utilizado. Las plasminas del equino y canino mostraron la misma KM por el sustrato cromogénico (0,438 mM, siendo esta la de mayor afinidad en este estudio y la humana la de menor afinidad (5,3 mM. También fueron determinadas la constante catalítica y la velocidad de conversión del sustrato cromogénico a producto. Los terminales-N de los plasminógenos de las ocho especies fueron determinados, y se encontraron diferencias entre el humano y los animales; así mismo entre algunos animales. Solo el porcino y el ovino no mostraron diferencia alguna en su terminal-N (DPPDDY. Se demostró la unificación del método de purificación de los plasminógenos para cualquier especie, las diferencias cinéticas de las ocho plasminas estudiadas, y las similitudes y diferencias en la secuencia de los terminales-N de las ocho especies.

  18. Environmental Factors Modulating the Stability and Enzymatic Activity of the Petrotoga mobilis Esterase (PmEst.

    Directory of Open Access Journals (Sweden)

    Jose L S Lopes

    Full Text Available Enzymes isolated from thermophilic organisms found in oil reservoirs can find applications in many fields, including the oleochemical, pharmaceutical, bioenergy, and food/dairy industries. In this study, in silico identification and recombinant production of an esterase from the extremophile bacteria Petrotoga mobilis (designated PmEst were performed. Then biochemical, bioinformatics and structural characterizations were undertaken using a combination of synchrotron radiation circular dichroism (SRCD and fluorescence spectroscopies to correlate PmEst stability and hydrolytic activity on different substrates. The enzyme presented a high Michaelis-Menten constant (KM 0.16 mM and optimum activity at ~55°C for p-nitrophenyl butyrate. The secondary structure of PmEst was preserved at acid pH, but not under alkaline conditions. PmEst was unfolded at high concentrations of urea or guanidine through apparently different mechanisms. The esterase activity of PmEst was preserved in the presence of ethanol or propanol and its melting temperature increased ~8°C in the presence of these organic solvents. PmEst is a mesophilic esterase with substrate preference towards short-to medium-length acyl chains. The SRCD data of PmEst is in agreement with the prediction of an α/β protein, which leads us to assume that it displays a typical fold of esterases from this family. The increased enzyme stability in organic solvents may enable novel applications for its use in synthetic biology. Taken together, our results demonstrate features of the PmEst enzyme that indicate it may be suitable for applications in industrial processes, particularly, when the use of polar organic solvents is required.

  19. Creatinine and urea biosensors based on a novel ammonium ion-selective copper-polyaniline nano-composite.

    Science.gov (United States)

    Zhybak, M; Beni, V; Vagin, M Y; Dempsey, E; Turner, A P F; Korpan, Y

    2016-03-15

    The use of a novel ammonium ion-specific copper-polyaniline nano-composite as transducer for hydrolase-based biosensors is proposed. In this work, a combination of creatinine deaminase and urease has been chosen as a model system to demonstrate the construction of urea and creatinine biosensors to illustrate the principle. Immobilisation of enzymes was shown to be a crucial step in the development of the biosensors; the use of glycerol and lactitol as stabilisers resulted in a significant improvement, especially in the case of the creatinine, of the operational stability of the biosensors (from few hours to at least 3 days). The developed biosensors exhibited high selectivity towards creatinine and urea. The sensitivity was found to be 85 ± 3.4 mAM(-1)cm(-2) for the creatinine biosensor and 112 ± 3.36 mAM(-1)cm(-2) for the urea biosensor, with apparent Michaelis-Menten constants (KM,app), obtained from the creatinine and urea calibration curves, of 0.163 mM for creatinine deaminase and 0.139 mM for urease, respectively. The biosensors responded linearly over the concentration range 1-125 µM, with a limit of detection of 0.5 µM and a response time of 15s. The performance of the biosensors in a real sample matrix, serum, was evaluated and a good correlation with standard spectrophotometric clinical laboratory techniques was found. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Fatty acid uptake in normal human myocardium

    International Nuclear Information System (INIS)

    Vyska, K.; Meyer, W.; Stremmel, W.; Notohamiprodjo, G.; Minami, K.; Machulla, H.J.; Gleichmann, U.; Meyer, H.; Koerfer, R.

    1991-01-01

    Fatty acid binding protein has been found in rat aortic endothelial cell membrane. It has been identified to be a 40-kDa protein that corresponds to a 40-kDa fatty acid binding protein with high affinity for a variety of long chain fatty acids isolated from rat heart myocytes. It is proposed that this endothelial membrane fatty acid binding protein might mediate the myocardial uptake of fatty acids. For evaluation of this hypothesis in vivo, influx kinetics of tracer-labeled fatty acids was examined in 15 normal subjects by scintigraphic techniques. Variation of the plasma fatty acid concentration and plasma perfusion rate has been achieved by modulation of nutrition state and exercise conditions. The clinical results suggest that the myocardial fatty acid influx rate is saturable by increasing fatty acid plasma concentration as well as by increasing plasma flow. For analysis of these data, functional relations describing fatty acid transport from plasma into myocardial tissue in the presence and absence of an unstirred layer were developed. The fitting of these relations to experimental data indicate that the free fatty acid influx into myocardial tissue reveals the criteria of a reaction on a capillary surface in the vicinity of flowing plasma but not of a reaction in extravascular space or in an unstirred layer and that the fatty acid influx into normal myocardium is a saturable process that is characterized by the quantity corresponding to the Michaelis-Menten constant, Km, and the maximal velocity, Vmax, 0.24 ± 0.024 mumol/g and 0.37 ± 0.013 mumol/g(g.min), respectively. These data are compatible with a nondiffusional uptake process mediated by the initial interaction of fatty acids with the 40-kDa membrane fatty acid binding protein of cardiac endothelial cells

  1. A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

    Science.gov (United States)

    Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

    2016-10-15

    The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Studies on the kinetics of absorption of phosphorus by rice (Orysa sativa L.) and beans (Phaseolus vulgaris L.)

    International Nuclear Information System (INIS)

    Baraibar, A.; Villamil, J.; Fiore, M.F.; Marcondes, R.F.; Muraoka, T.; Cabral, C.P.; Malavolta, M.L.; Malavolta, E.

    1987-01-01

    Three experiments were conducted under controlled conditions with the objectives of evaluating the effect of different concentrations of phosphorus and on the presence of other ions on the kinetic of absorption. Excised roots of rice and bean were placed in aereated solutions containing increasing concentrations of NaH 2 PO 4 (10 -7 M to 5x10 -2 M) during 90 minutes. The rate of absorption (v = umols P/g dry matter) and the kinetic constants Vmax and Km were determined. Similar procedure was used to to evaluate the interaction of Mg +2 , Al +3 , K + , N-NH 4 + , N-NO 3 - and N-ureia in the uptake of phosphorus during 120 minutes. In another experiment, the effect of the presence of Mg +2 and/for Al +3 in the uptake and redistribution of phosphorus, was evaluated by varying the external concentration (1 ppm, 5 ppm, 10 ppm and 20 ppm) during a period of 17 hours, and utilizing whole rice plants. It was observed a dual mechanism, with two phases following the Michaelis-Menten kinetics and with transition phase 1 - 50 x 10 -5 M. The best explanation of the experimental data was obtained, by transforming the data in accordance with HOFSTEE (1952). Bean was more efficient than rice in the first phase of uptake (higher Vmax). Al 3 had a clear stimulatory effect on the uptake of phosphorus, promoting, however, the anion fixation in the root at lower concentrations. At the highest concentrations (20 ppm) of phosphorus this effect was not evident. No effect on the uptake was observed with Mg +2 , K + and different forms of nitrogen. Urea could have a depressive effect although, not significant. Possible mechanisms involved are discussed. (author) [pt

  3. MODIS 3km Aerosol Product: Algorithm and Global Perspective

    Science.gov (United States)

    Remer, L. A.; Mattoo, S.; Levy, R. C.; Munchak, L.

    2013-01-01

    After more than a decade of producing a nominal 10 km aerosol product based on the dark target method, the MODIS aerosol team will be releasing a nominal 3 km product as part of their Collection 6 release. The new product differs from the original 10 km product only in the manner in which reflectance pixels are ingested, organized and selected by the aerosol algorithm. Overall, the 3 km product closely mirrors the 10 km product. However, the finer resolution product is able to retrieve over ocean closer to islands and coastlines, and is better able to resolve fine aerosol features such as smoke plumes over both ocean and land. In some situations, it provides retrievals over entire regions that the 10 km product barely samples. In situations traditionally difficult for the dark target algorithm, such as over bright or urban surfaces the 3 km product introduces isolated spikes of artificially high aerosol optical depth (AOD) that the 10 km algorithm avoids. Over land, globally, the 3 km product appears to be 0.01 to 0.02 higher than the 10 km product, while over ocean, the 3 km algorithm is retrieving a proportionally greater number of very low aerosol loading situations. Based on collocations with ground-based observations for only six months, expected errors associated with the 3 km land product are determined to be greater than for the 10 km product: 0.05 0.25 AOD. Over ocean, the suggestion is for expected errors to be the same as the 10 km product: 0.03 0.05 AOD. The advantage of the product is on the local scale, which will require continued evaluation not addressed here. Nevertheless, the new 3 km product is expected to provide important information complementary to existing satellite-derived products and become an important tool for the aerosol community.

  4. Optimization of enzyme parameters for fermentative production of biorenewable fuels and chemicals

    Directory of Open Access Journals (Sweden)

    Ping Liu

    2012-10-01

    Full Text Available Microbial biocatalysts such as Escherichia coli and Saccharomyces cerevisiae have been extensively subjected to Metabolic Engineering for the fermentative production of biorenewable fuels and chemicals. This often entails the introduction of new enzymes, deletion of unwanted enzymes and efforts to fine-tune enzyme abundance in order to attain the desired strain performance. Enzyme performance can be quantitatively described in terms of the Michaelis-Menten type parameters Km, turnover number kcat and Ki, which roughly describe the affinity of an enzyme for its substrate, the speed of a reaction and the enzyme sensitivity to inhibition by regulatory molecules. Here we describe examples of where knowledge of these parameters have been used to select, evolve or engineer enzymes for the desired performance and enabled increased production of biorenewable fuels and chemicals. Examples include production of ethanol, isobutanol, 1-butanol and tyrosine and furfural tolerance. The Michaelis-Menten parameters can also be used to judge the cofactor dependence of enzymes and quantify their preference for NADH or NADPH. Similarly, enzymes can be selected, evolved or engineered for the preferred cofactor preference. Examples of exporter engineering and selection are also discussed in the context of production of malate, valine and limonene.

  5. OPTIMIZATION OF ENZYME PARAMETERS FOR FERMENTATIVE PRODUCTION OF BIORENEWABLE FUELS AND CHEMICALS

    Directory of Open Access Journals (Sweden)

    Laura R. Jarboe

    2012-10-01

    Full Text Available Microbial biocatalysts such as Escherichia coli and Saccharomyces cerevisiae have been extensively subjected to Metabolic Engineering for the fermentative production of biorenewable fuels and chemicals. This often entails the introduction of new enzymes, deletion of unwanted enzymes and efforts to fine-tune enzyme abundance in order to attain the desired strain performance. Enzyme performance can be quantitatively described in terms of the Michaelis-Menten type parameters Km, turnover number kcat and Ki, which roughly describe the affinity of an enzyme for its substrate, the speed of a reaction and the enzyme sensitivity to inhibition by regulatory molecules. Here we describe examples of where knowledge of these parameters have been used to select, evolve or engineer enzymes for the desired performance and enabled increased production of biorenewable fuels and chemicals. Examples include production of ethanol, isobutanol, 1-butanol and tyrosine and furfural tolerance. The Michaelis-Menten parameters can also be used to judge the cofactor dependence of enzymes and quantify their preference for NADH or NADPH. Similarly, enzymes can be selected, evolved or engineered for the preferred cofactor preference. Examples of exporter engineering and selection are also discussed in the context of production of malate, valine and limonene.

  6. Elongational flow of polymer melts at constant strain rate, constant stress and constant force

    Science.gov (United States)

    Wagner, Manfred H.; Rolón-Garrido, Víctor H.

    2013-04-01

    Characterization of polymer melts in elongational flow is typically performed at constant elongational rate or rarely at constant tensile stress conditions. One of the disadvantages of these deformation modes is that they are hampered by the onset of "necking" instabilities according to the Considère criterion. Experiments at constant tensile force have been performed even more rarely, in spite of the fact that this deformation mode is free from necking instabilities and is of considerable industrial relevance as it is the correct analogue of steady fiber spinning. It is the objective of the present contribution to present for the first time a full experimental characterization of a long-chain branched polyethylene melt in elongational flow. Experiments were performed at constant elongation rate, constant tensile stress and constant tensile force by use of a Sentmanat Extensional Rheometer (SER) in combination with an Anton Paar MCR301 rotational rheometer. The accessible experimental window and experimental limitations are discussed. The experimental data are modelled by using the Wagner I model. Predictions of the steady-start elongational viscosity in constant strain rate and creep experiments are found to be identical, albeit only by extrapolation of the experimental data to Hencky strains of the order of 6. For constant stress experiments, a minimum in the strain rate and a corresponding maximum in the elongational viscosity is found at a Hencky strain of the order of 3, which, although larger than the steady-state value, follows roughly the general trend of the steady-state elongational viscosity. The constitutive analysis also reveals that constant tensile force experiments indicate a larger strain hardening potential than seen in constant elongation rate or constant tensile stress experiments. This may be indicative of the effect of necking under constant elongation rate or constant tensile stress conditions according to the Considère criterion.

  7. Use of an uncertainty analysis for genome-scale models as a prediction tool for microbial growth processes in subsurface environments.

    Science.gov (United States)

    Klier, Christine

    2012-03-06

    The integration of genome-scale, constraint-based models of microbial cell function into simulations of contaminant transport and fate in complex groundwater systems is a promising approach to help characterize the metabolic activities of microorganisms in natural environments. In constraint-based modeling, the specific uptake flux rates of external metabolites are usually determined by Michaelis-Menten kinetic theory. However, extensive data sets based on experimentally measured values are not always available. In this study, a genome-scale model of Pseudomonas putida was used to study the key issue of uncertainty arising from the parametrization of the influx of two growth-limiting substrates: oxygen and toluene. The results showed that simulated growth rates are highly sensitive to substrate affinity constants and that uncertainties in specific substrate uptake rates have a significant influence on the variability of simulated microbial growth. Michaelis-Menten kinetic theory does not, therefore, seem to be appropriate for descriptions of substrate uptake processes in the genome-scale model of P. putida. Microbial growth rates of P. putida in subsurface environments can only be accurately predicted if the processes of complex substrate transport and microbial uptake regulation are sufficiently understood in natural environments and if data-driven uptake flux constraints can be applied.

  8. Inhibition of serotonin transport by (+)McN5652 is noncompetitive

    Energy Technology Data Exchange (ETDEWEB)

    Hummerich, Rene [Biochemical Laboratory, Central Institute of Mental Health, 68159 Mannheim (Germany); Schulze, Oliver [Department of Nuclear Medicine, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg (Germany); Raedler, Thomas [Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg (Germany); Mikecz, Pal [Department of Nuclear Medicine, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg (Germany); Reimold, Matthias [Department of Nuclear Medicine, University Hospital Tuebingen, D-72076 Tuebingen (Germany); Brenner, Winfried [Department of Nuclear Medicine, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg (Germany); Clausen, Malte [Department of Nuclear Medicine, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg (Germany); Schloss, Patrick [Biochemical Laboratory, Central Institute of Mental Health, 68159 Mannheim (Germany); Buchert, Ralph [Department of Nuclear Medicine, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg (Germany)]. E-mail: buchert@uke.uni-hamburg.de

    2006-04-15

    Introduction: Imaging of the serotonergic innervation of the brain using positron emission tomography (PET) with the serotonin transporter (SERT) ligand [{sup 11C}] (+)McN5652 might be affected by serotonin in the synaptic cleft if there is relevant interaction between [{sup 11}C] (+)McN5652 and serotonin at the SERT. The aim of the present study therefore was to pharmacologically characterize the interaction of [{sup 11}C] (+)McN5652 and serotonin at the SERT. Methods: In vitro saturation analyses of [{sup 3}H]serotonin uptake into HEK293 cells stably expressing the human SERT were performed in the absence and presence of unlabelled (+)McN5652. Data were evaluated assuming Michaelis-Menten kinetics. Results: Unlabelled (+)McN5652 significantly reduced the maximal rate of serotonin transport V {sub max} of SERT without affecting the Michaelis-Menten constant K {sub M}. Conclusions: This finding indicates that (+)McN5652 inhibits serotonin transport through the SERT in a noncompetitive manner. This might suggest that [{sup 11}C] (+)McN5652 PET is not significantly affected by endogenous serotonin.

  9. Use of CdSe/ZnS luminescent quantum dots incorporated within sol-gel matrix for urea detection

    International Nuclear Information System (INIS)

    Duong, Hong Dinh; Rhee, Jong Il

    2008-01-01

    In this work, urea detection techniques based on the pH sensitivity of CdSe/ZnS QDs were developed using three types of sol-gel membranes: a QD-entrapped membrane, urease-immobilized membrane and double layer consisting of a QD-entrapped membrane and urease-immobilized membrane. The surface morphology of the sol-gel membranes deposited on the wells in a 24-well microtiter plate was investigated. The linear detection range of urea was in the range of 0-10 mM with the three types of sol-gel membranes. The urea detection technique based on the double layer consisting of the QD-entrapped membrane and urease-immobilized membrane resulted in the highest sensitivity to urea due to the Michaelis-Menten kinetic parameters. That is, the Michaelis-Menten constant (K m =2.0745 mM) of the free urease in the QD-entrapped membrane was about 4-fold higher than that (K m =0.549 mM) of the immobilized urease in the urease-immobilized membrane and about 12-fold higher than that (K m =0.1698 mM) of the immobilized urease in the double layer. The good stability of the three sol-gel membranes for urea sensing over 2 months showed that the use of sol-gel membranes immobilized with QDs or an enzyme is suitable for biomedical and environmental applications

  10. A Critical View on In Vitro Analysis of P-glycoprotein (P-gp) Transport Kinetics.

    Science.gov (United States)

    Saaby, Lasse; Brodin, Birger

    2017-09-01

    Transport proteins expressed in the different barriers of the human body can have great implications on absorption, distribution, and excretion of drug compounds. Inhibition or saturation of a transporter can potentially alter these absorbtion, distribution, metabolism and elimination properties and thereby also the pharmacokinetic profile and bioavailability of drug compounds. P-glycoprotein (P-gp, ABCB1) is an efflux transporter which is present in most of the barriers of the body, including the small intestine, the blood-brain barrier, the liver, and the kidney. In all these tissues, P-gp may mediate efflux of drug compounds and may also be a potential site for drug-drug interactions. Consequently, there is a need to be able to predict the saturation and inhibition of P-gp and other transporters in vivo. For this purpose, Michaelis-Menten steady-state analysis has been applied to estimate kinetic parameters, such as K m and V max , for carrier-mediated transport, whereas half-maximal inhibitor concentration (IC 50 ) and the disassociation constant for an inhibitor/P-gp complex (K i ) have been determined to estimate P-gp inhibition. This review addresses in vitro methods commonly used to study P-gp transport kinetics and aims at providing a critical evaluation of the application of steady-state Michaelis-Menten analysis of kinetic parameters for substrate/P-gp interactions. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  11. Crude Aloe vera Gel Shows Antioxidant Propensities and Inhibits Pancreatic Lipase and Glucose Movement In Vitro

    Science.gov (United States)

    Taukoorah, Urmeela; Mahomoodally, M. Fawzi

    2016-01-01

    Aloe vera gel (AVG) is traditionally used in the management of diabetes, obesity, and infectious diseases. The present study aimed to investigate the inhibitory potential of AVG against α-amylase, α-glucosidase, and pancreatic lipase activity in vitro. Enzyme kinetic studies using Michaelis-Menten (K m) and Lineweaver-Burk equations were used to establish the type of inhibition. The antioxidant capacity of AVG was evaluated for its ferric reducing power, 2-diphenyl-2-picrylhydrazyl hydrate scavenging ability, nitric oxide scavenging power, and xanthine oxidase inhibitory activity. The glucose entrapment ability, antimicrobial activity, and total phenolic, flavonoid, tannin, and anthocyanin content were also determined. AVG showed a significantly higher percentage inhibition (85.56 ± 0.91) of pancreatic lipase compared to Orlistat. AVG was found to increase the Michaelis-Menten constant and decreased the maximal velocity (V max) of lipase, indicating mixed inhibition. AVG considerably inhibits glucose movement across dialysis tubes and was comparable to Arabic gum. AVG was ineffective against the tested microorganisms. Total phenolic and flavonoid contents were 66.06 ± 1.14 (GAE)/mg and 60.95 ± 0.97 (RE)/mg, respectively. AVG also showed interesting antioxidant properties. The biological activity observed in this study tends to validate some of the traditional claims of AVG as a functional food. PMID:26880905

  12. Inhibition of serotonin transport by (+)McN5652 is noncompetitive

    International Nuclear Information System (INIS)

    Hummerich, Rene; Schulze, Oliver; Raedler, Thomas; Mikecz, Pal; Reimold, Matthias; Brenner, Winfried; Clausen, Malte; Schloss, Patrick; Buchert, Ralph

    2006-01-01

    Introduction: Imaging of the serotonergic innervation of the brain using positron emission tomography (PET) with the serotonin transporter (SERT) ligand [ 11C ] (+)McN5652 might be affected by serotonin in the synaptic cleft if there is relevant interaction between [ 11 C] (+)McN5652 and serotonin at the SERT. The aim of the present study therefore was to pharmacologically characterize the interaction of [ 11 C] (+)McN5652 and serotonin at the SERT. Methods: In vitro saturation analyses of [ 3 H]serotonin uptake into HEK293 cells stably expressing the human SERT were performed in the absence and presence of unlabelled (+)McN5652. Data were evaluated assuming Michaelis-Menten kinetics. Results: Unlabelled (+)McN5652 significantly reduced the maximal rate of serotonin transport V max of SERT without affecting the Michaelis-Menten constant K M . Conclusions: This finding indicates that (+)McN5652 inhibits serotonin transport through the SERT in a noncompetitive manner. This might suggest that [ 11 C] (+)McN5652 PET is not significantly affected by endogenous serotonin

  13. Spectrophotometric determination of association constant

    DEFF Research Database (Denmark)

    2016-01-01

    Least-squares 'Systematic Trial-and-Error Procedure' (STEP) for spectrophotometric evaluation of association constant (equilibrium constant) K and molar absorption coefficient E for a 1:1 molecular complex, A + B = C, with error analysis according to Conrow et al. (1964). An analysis of the Charge...

  14. Linear and Nonlinear Infrasound Propagation to 1000 km

    Science.gov (United States)

    2015-12-15

    AFRL-RV-PS- AFRL-RV-PS- TR-2016-0017 TR-2016-0017 LINEAR AND NONLINEAR INFRASOUND PROPAGATION TO 1000 KM Catherine de Groot-Hedlin Scripps...Nonlinear Infrasound Propagation to 1000 km 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6. AUTHOR(S) Catherine de Groot

  15. 7 CFR 29.1035 - Mixed color (KM).

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Mixed color (KM). 29.1035 Section 29.1035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1035 Mixed color (KM). Distinctly different colors of the type mingled together. (See...

  16. Status of the KM3NeT project

    International Nuclear Information System (INIS)

    Katz, U.F.

    2009-01-01

    KM3NeT is a future research infrastructure in the Mediterranean Sea, hosting a cubic-kilometre scale neutrino telescope and nodes for associated sciences such as marine biology, oceanology and geophysics. The status of the KM3NeT project and the progress made in the EU-funded Design Study is reviewed. Some physics studies indicating the sensitivity of the KM3NeT neutrino telescope are highlighted and selected major technical design options to be further pursued are described. Finally, the remaining steps towards construction of KM3NeT will be discussed. This document reflects the status of the KM3NeT Conceptual Design Report (CDR), which has been presented to the public for the first time at the VLVnT08 Workshop.

  17. Knowledge Management (KM): a new management paradigm in MINT

    International Nuclear Information System (INIS)

    Amy Hamijah Ab Hamid

    2006-01-01

    Knowledge management (KM) is one of the leading approaches to improve organizational benefits by introducing into an organization a range of specific processes and practices for identifying and capturing knowledge, know-how, expertise and other intellectual properties, and for making such knowledge assets available for transfer and reuse across the organization. This paper identified and compared some of the KM theories, methodologies and best practices from various literatures. It also pointed out the KM Life Cycle and KM Transformation through Organization as a prior case study. This forms the guidelines for MINT, local agencies and overseas conglomerates experiences through some challenges and opportunities identification. As MINT is still in the early stages in doing so, it is important to start small but continuously doing incremental improvement overtime. Finally, an improvement towards KM culture in MINT is proposed referring to the ideas and facts stated above

  18. Varying Constants, Gravitation and Cosmology

    Directory of Open Access Journals (Sweden)

    Jean-Philippe Uzan

    2011-03-01

    Full Text Available Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. Thus, it is of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, solar system observations, meteorite dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.

  19. Acoustic calibration for the KM3NeT pre-production module

    Energy Technology Data Exchange (ETDEWEB)

    Enzenhöfer, A., E-mail: alexander.enzenhoefer@physik.uni-erlangen.de [Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, D-91058 Erlangen (Germany)

    2013-10-11

    The proposed large scale Cherenkov neutrino telescope KM3NeT will carry photo-sensors on flexible structures, the detection units. The Mediterranean Sea, where KM3NeT will be installed, constitutes a highly dynamic environment in which the detection units are constantly in motion. Thus it is necessary to monitor the exact sensor positions continuously to achieve the desired resolution for the neutrino telescope. A common way to perform this monitoring is the use of acoustic positioning systems with emitters and receivers based on the piezoelectric effect. The acoustic receivers are attached to detection units whereas the emitters are located at known positions on the sea floor. There are complete commercial systems for this application with sufficient precision. But these systems are limited in the use of their data and inefficient as they were designed to perform only this single task. Several working groups in the KM3NeT consortium are cooperating to custom-design a positioning system for the specific requirements of KM3NeT. Most of the studied solutions hold the possibility to extend the application area from positioning to additional tasks like acoustic particle detection or monitoring of the deep-sea acoustic environment. The KM3NeT Pre-Production Module (PPM) is a test system to verify the correct operation and interoperability of the major involved hardware and software components developed for KM3NeT. In the context of the PPM, alternative designs of acoustic sensors including small piezoelectric elements equipped with preamplifiers inside the same housing as the optical sensors will be tested. These will be described in this article.

  20. Constant envelope OFDM scheme for 6PolSK-QPSK

    Science.gov (United States)

    Li, Yupeng; Ding, Ding

    2018-03-01

    A constant envelope OFDM scheme with phase modulator (PM-CE-OFDM) for 6PolSK-QPSK modulation was demonstrated. Performance under large fiber launch power is measured to check its advantages in counteracting fiber nonlinear impairments. In our simulation, PM-CE-OFDM, RF-assisted constant envelope OFDM (RF-CE-OFDM) and conventional OFDM (Con-OFDM) are transmitted through 80 km standard single mode fiber (SSMF) single channel and WDM system. Simulation results confirm that PM-CE-OFDM has best performance in resisting fiber nonlinearity. In addition, benefiting from the simple system structure, the complexity and cost of PM-CE-OFDM system could be reduced effectively.

  1. Value of the Cosmological Constant in Emergent Quantum Gravity

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, Craig [Fermilab

    2018-03-30

    It is suggested that the exact value of the cosmological constant could be derived from first principles, based on entanglement of the Standard Model field vacuum with emergent holographic quantum geometry. For the observed value of the cosmological constant, geometrical information is shown to agree closely with the spatial information density of the QCD vacuum, estimated in a free-field approximation. The comparison is motivated by a model of exotic rotational fluctuations in the inertial frame that can be precisely tested in laboratory experiments. Cosmic acceleration in this model is always positive, but fluctuates with characteristic coherence length $\\approx 100$km and bandwidth $\\approx 3000$ Hz.

  2. Stabilized power constant alimentation; Alimentation regulee a puissance constante

    Energy Technology Data Exchange (ETDEWEB)

    Roussel, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    The study and realization of a stabilized power alimentation variable from 5 to 100 watts are described. In order to realize a constant power drift of Lithium compensated diodes, we have searched a 1 per cent precision of regulation and a response time minus than 1 sec. Recent components like Hall multiplicator and integrated amplifiers give this possibility and it is easy to use permutable circuits. (author) [French] On decrit l'etude et la realisation d'une alimentation a puissance constante reglable dans une gamme de 5 a 100 watts. Prevue pour le drift a puissance constante des diodes compensees au lithium, l'etude a ete menee en vue d'obtenir une precision de regulation de 1 pour cent et un temps de reponse inferieur a la seconde. Des systemes recents tels que multiplicateurs a effet Hall et circuits integres ont permis d'atteindre ce but tout en facilitant l'emploi de modules interchangeables. (auteur)

  3. From the Rydberg constant to the fundamental constants metrology

    International Nuclear Information System (INIS)

    Nez, F.

    2005-06-01

    This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)

  4. Learning Read-constant Polynomials of Constant Degree modulo Composites

    DEFF Research Database (Denmark)

    Chattopadhyay, Arkadev; Gavaldá, Richard; Hansen, Kristoffer Arnsfelt

    2011-01-01

    Boolean functions that have constant degree polynomial representation over a fixed finite ring form a natural and strict subclass of the complexity class \\textACC0ACC0. They are also precisely the functions computable efficiently by programs over fixed and finite nilpotent groups. This class...... is not known to be learnable in any reasonable learning model. In this paper, we provide a deterministic polynomial time algorithm for learning Boolean functions represented by polynomials of constant degree over arbitrary finite rings from membership queries, with the additional constraint that each variable...

  5. Temperature sensitivity of extracellular enzyme kinetics in subtropical wetland soils under different nutrient and water level conditions

    Science.gov (United States)

    Goswami, S.; Inglett, K.; Inglett, P.

    2012-12-01

    Microbial extracellular enzymes play an important role in the initial steps of soil organic matter decomposition and are involved in regulating nutrient cycle processes. Moreover, with the recent concern of climate change, microbial extracellular enzymes may affect the functioning (C losses, C sequestration, greenhouse gas emissions, vegetation changes) of different ecosystems. Hence, it is imperative to understand the biogeochemical processes that may be climate change sensitive. Here, we have measured the Michaelis Menten Kinetics [maximal rate of velocity (Vmax) and half-saturation constant (Km)] of 6 enzymes involved in soil organic matter decomposition (phosphatase, phosphodiesterase, β-D-glucosidase, cellobiohydrolase, leucine aminopeptidase, N-Acetyl-β-D glucosaminidase) in different nutrient(P) concentration both aerobically and anaerobically in Everglade water conservation area 2A (F1, F4-slough and U3-slough). Temperature sensitivity of different enzymes is assessed within soil of different P concentrations. We hypothesized that the temperature sensitivity of the enzyme changes with the biogeochemical conditions including water level and nutrient condition. Furthermore, we have tested specific hypothesis that higher P concentration will initiate more C demand for microbes leading to higher Vmax value for carbon processing enzymes in high P site. We found temperature sensitivity of all enzymes for Vmax and Km under both aerobic and anaerobic condition ranges from 0.6 to 3.2 for Vmax and 0.5 to 2.5 for Km. Q10 values of Km for glucosidase indicate more temperature sensitivity under anaerobic condition. Under aerobic condition higher temperature showed significant effect on Vmax for bisphosphatase between high P and low P site. Decreasing P concentration from F1 site to U3-S site had showed significant effect in all temperature on carbon processing enzyme. This suggests that in high P site, microbes will use more carbon-processing enzyme to get more carbon

  6. New model for the lunar interior to 250 km

    International Nuclear Information System (INIS)

    Piwinskii, A.J.; Duba, A.G.

    1975-01-01

    A new model for the structure of the lunar interior to about a 250-km depth is proposed. It is suggested that this region is composed of plagioclase-bearing rocks, and that the 65-km seismic discontinuity represents the appearance of garnet. A variety of rock types mainly composed of plagioclase, pyroxene, olivine and garnet is envisioned, with at least half of the outer 250 km of the moon made of plagioclase, which dominates the electrical conductivity. This model agrees with recent petrological and electrical conductivity results and does not violate velocity-depth profiles obtained from elastic-wave studies of lunar and terrestrial materials. (U.S.)

  7. On the Luminosity Distance and the Hubble Constant

    OpenAIRE

    Yuri Heymann

    2013-01-01

    By differentiating luminosity distance with respect to time using its standard formula we find that the peculiar velocity is a time varying velocity of light. Therefore, a new definition of the luminosity distance is provided such that the peculiar velocity is equal to c. Using this definition a Hubble constant H0 = 67.3 km s−1 Mpc−1 is obtained from supernovae data.

  8. From the Rydberg constant to the fundamental constants metrology; De la constante de Rydberg a la metrologie des constantes fondamentales

    Energy Technology Data Exchange (ETDEWEB)

    Nez, F

    2005-06-15

    This document reviews the theoretical and experimental achievements of the author since the beginning of his scientific career. This document is dedicated to the spectroscopy of hydrogen, deuterium and helium atoms. The first part is divided into 6 sub-sections: 1) the principles of hydrogen spectroscopy, 2) the measurement of the 2S-nS/nD transitions, 3) other optical frequency measurements, 4) our contribution to the determination of the Rydberg constant, 5) our current experiment on the 1S-3S transition, 6) the spectroscopy of the muonic hydrogen. Our experiments have improved the accuracy of the Rydberg Constant by a factor 25 in 15 years and we have achieved the first absolute optical frequency measurement of a transition in hydrogen. The second part is dedicated to the measurement of the fine structure constant and the last part deals with helium spectroscopy and the search for optical references in the near infrared range. (A.C.)

  9. Systematics of constant roll inflation

    Science.gov (United States)

    Anguelova, Lilia; Suranyi, Peter; Wijewardhana, L. C. R.

    2018-02-01

    We study constant roll inflation systematically. This is a regime, in which the slow roll approximation can be violated. It has long been thought that this approximation is necessary for agreement with observations. However, recently it was understood that there can be inflationary models with a constant, and not necessarily small, rate of roll that are both stable and compatible with the observational constraint ns ≈ 1. We investigate systematically the condition for such a constant-roll regime. In the process, we find a whole new class of inflationary models, in addition to the known solutions. We show that the new models are stable under scalar perturbations. Finally, we find a part of their parameter space, in which they produce a nearly scale-invariant scalar power spectrum, as needed for observational viability.

  10. Global 1-km Sea Surface Temperature (G1SST)

    Data.gov (United States)

    National Aeronautics and Space Administration — JPL OurOcean Portal: A daily, global Sea Surface Temperature (SST) data set is produced at 1-km (also known as ultra-high resolution) by the JPL ROMS (Regional Ocean...

  11. Strain fluctuations and elastic constants

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, M.; Rahman, A.

    1982-03-01

    It is shown that the elastic strain fluctuations are a direct measure of elastic compliances in a general anisotropic medium; depending on the ensemble in which the fluctuation is measured either the isothermal or the adiabatic compliances are obtained. These fluctuations can now be calculated in a constant enthalpy and pressure, and hence, constant entropy, ensemble due to recent develpments in the molecular dynamics techniques. A calculation for a Ni single crystal under uniform uniaxial 100 tensile or compressive load is presented as an illustration of the relationships derived between various strain fluctuations and the elastic modulii. The Born stability criteria and the behavior of strain fluctuations are shown to be related.

  12. Status of the KM3NeT project

    International Nuclear Information System (INIS)

    Margiotta, A

    2014-01-01

    KM3NeT is a deep-sea research infrastructure being constructed in the Mediterranean Sea. It will be installed at three sites: KM3NeT-Fr, offshore Toulon, France, KM3NeT-It, offshore Portopalo di Capo Passero, Sicily (Italy) and KM3NeT-Gr, offshore Pylos, Peloponnese, Greece. It will host the next generation Cherenkov neutrino telescope and nodes for a deep sea multidisciplinary observatory, providing oceanographers, marine biologists, and geophysicists with real time measurements. The neutrino telescope will search for Galactic and extra-Galactic sources of neutrinos, complementing IceCube in its field of view. The detector will have a modular structure and consists of six building blocks, each including about one hundred Detection Units (DUs). Each DU will be equipped with 18 multi-PMT digital optical modules. The first phase of construction has started and shore and deep-sea infrastructures hosting the future KM3NeT detector are being prepared in France near Toulon and in Italy, near Capo Passero in Sicily. The technological solutions for KM3NeT and the expected performance of the detector are presented and discussed

  13. Magma reservoir at Mt. Vesuvius: Deeper than 10 km

    International Nuclear Information System (INIS)

    Natale, M.; Luongo, G.; Nunziata, C.; Panza, G.F.

    2005-07-01

    One- and two-dimensional Vp models were obtained by TomoVes experiment, all characterized by low Vp in the uppermost 500 m and a sharp discontinuity at about 2-3 km beneath the volcano. Large amplitude late arrivals were identified as P- to S-phases converted at the top, between 8 and 10 km deep, of a low velocity layer with a dramatic drop of Vs, from approximately 3.6 km/s to less than 1.0 km/s. Here we synthesize the interpretation of Rayleigh wave dispersion measurements, made by several authors, to delineate the extent of such anomalous layer of hot, partially molten, crust material. Our non-linear inversion of broad-band dispersion measurements, gives a thickness not greater than 0.35 km, if we assume Vs equal to 1.0 km/s. The volume occupied by this very low velocity layer, sill shaped, is compatible with the size of Mt. Vesuvius cone, but it develops above a much larger hot mass which could be the parental source as the erupted products are only few percent of magma chamber. (author)

  14. Universal relation between spectroscopic constants

    Indian Academy of Sciences (India)

    (3) The author has used eq. (6) of his paper to calculate De. This relation leads to a large deviation from the correct value depending upon the extent to which experimental values are known. Guided by this fact, in our work, we used experimentally observed De values to derive the relation between spectroscopic constants.

  15. Tachyon constant-roll inflation

    Science.gov (United States)

    Mohammadi, A.; Saaidi, Kh.; Golanbari, T.

    2018-04-01

    The constant-roll inflation is studied where the inflaton is taken as a tachyon field. Based on this approach, the second slow-roll parameter is taken as a constant which leads to a differential equation for the Hubble parameter. Finding an exact solution for the Hubble parameter is difficult and leads us to a numerical solution for the Hubble parameter. On the other hand, since in this formalism the slow-roll parameter η is constant and could not be assumed to be necessarily small, the perturbation parameters should be reconsidered again which, in turn, results in new terms appearing in the amplitude of scalar perturbations and the scalar spectral index. Utilizing the numerical solution for the Hubble parameter, we estimate the perturbation parameter at the horizon exit time and compare it with observational data. The results show that, for specific values of the constant parameter η , we could have an almost scale-invariant amplitude of scalar perturbations. Finally, the attractor behavior for the solution of the model is presented, and we determine that the feature could be properly satisfied.

  16. Similarities and Differences in Pacing Patterns in a 161-km and 101-km Ultra-Distance Road Race.

    Science.gov (United States)

    Tan, Philip L S; Tan, Frankie H Y; Bosch, Andrew N

    2016-08-01

    Tan, PLS, Tan, FHY, and Bosch, AN. Similarities and differences in pacing patterns in a 161-km and 101-km ultra-distance road race. J Strength Cond Res 30(8): 2145-2155, 2016-The purpose of this study was to establish and compare the pacing patterns of fast and slow finishers in a tropical ultra-marathon. Data were collected from the Craze Ultra-marathon held on the 22nd and 21st of September in 2012 and 2013, respectively. Finishers of the 161-km (N = 47) and 101-km (N = 120) categories of the race were divided into thirds (groups A-C) by merit of finishing time. Altogether, 17 and 11 split times were recorded for the 161-km and 101-km finishers, respectively, and used to calculate the mean running speed for each distance segment. Running speed for the first segment was normalized to 100, with all subsequent splits adjusted accordingly. Running speed during the last 5 km was calculated against the mean race pace to establish the existence of an end spurt. A reverse J-shaped pacing profile was demonstrated in all groups for both distance categories and only 38% of the finishers executed an end spurt. In the 101-km category, in comparison with groups B and C, group A maintained a significantly more even pace (p = 0.013 and 0.001, respectively) and completed the race at a significantly higher percent of initial starting speed (p = 0.001 and 0.001, respectively). Descriptive data also revealed that the top 5 finishers displayed a "herd-behavior" by staying close to the lead runner in the initial portion of the race. These findings demonstrate that to achieve a more even pace, recreational ultra-runners should adopt a patient sustainable starting speed, with less competitive runners setting realistic performance goals whereas competitive runners with a specific time goal to consider running in packs of similar pace.

  17. Stabilized power constant alimentation; Alimentation regulee a puissance constante

    Energy Technology Data Exchange (ETDEWEB)

    Roussel, L. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-06-01

    The study and realization of a stabilized power alimentation variable from 5 to 100 watts are described. In order to realize a constant power drift of Lithium compensated diodes, we have searched a 1 per cent precision of regulation and a response time minus than 1 sec. Recent components like Hall multiplicator and integrated amplifiers give this possibility and it is easy to use permutable circuits. (author) [French] On decrit l'etude et la realisation d'une alimentation a puissance constante reglable dans une gamme de 5 a 100 watts. Prevue pour le drift a puissance constante des diodes compensees au lithium, l'etude a ete menee en vue d'obtenir une precision de regulation de 1 pour cent et un temps de reponse inferieur a la seconde. Des systemes recents tels que multiplicateurs a effet Hall et circuits integres ont permis d'atteindre ce but tout en facilitant l'emploi de modules interchangeables. (auteur)

  18. Development of prediction models for radioactive caesium distribution within the 80-km radius of the Fukushima Daiichi nuclear power plant

    International Nuclear Information System (INIS)

    Kinase, Sakae; Sato, Satoshi; Saito, Kimiaki; Takahashi, Tomoyuki; Sakamoto, Ryuichi

    2014-01-01

    Preliminary prediction models have been studied for the radioactive caesium distribution within the 80-km radius of the Fukushima Daiichi nuclear power plant. The models were represented by exponential functions using ecological half-life of radioactive caesium in the environment. The ecological half-lives were derived from the changes in ambient dose equivalent rates through vehicle-borne surveys. It was found that the ecological half-lives of radioactive caesium were not constant within the 80-km radius of the Fukushima Daiichi nuclear power plant. The ecological half-life of radioactive caesium in forest areas was found to be much larger than that in urban and water areas. (authors)

  19. Evolution of the solar constant

    International Nuclear Information System (INIS)

    Newman, M.J.

    1978-01-01

    The ultimate source of the energy utilized by life on Earth is the Sun, and the behavior of the Sun determines to a large extent the conditions under which life originated and continues to thrive. What can be said about the history of the Sun. Has the solar constant, the rate at which energy is received by the Earth from the Sun per unit area per unit time, been constant at its present level since Archean times. Three mechanisms by which it has been suggested that the solar energy output can vary with time are discussed, characterized by long (approx. 10 9 years), intermediate (approx. 10 8 years), and short (approx. years to decades) time scales

  20. Calculation of magnetic hyperfine constants

    International Nuclear Information System (INIS)

    Bufaical, R.F.; Maffeo, B.; Brandi, H.S.

    1975-01-01

    The magnetic hyperfine constants of the V sub(K) center in CaF 2 , SrF 2 and BaF 2 have been calculated assuming a phenomenological model, based on the F 2 - 'central molucule', to describe the wavefunction of the defect. Calculations have shown that introduction of a small degree of covalence, between this central molecule and neighboring ions, is necessary to improve the electronic structure description of the defect. It was also shown that the results for the hyperfine constants are strongly dependent on the relaxations of the ions neighboring the central molecule; these relaxations have been determined by fitting the experimental data. The present results are compared with other previous calculations where similar and different theoretical methods have been used

  1. On the gravitational constant change

    International Nuclear Information System (INIS)

    Milyukov, V.K.

    1986-01-01

    The nowadays viewpoint on the problem of G gravitational constant invariability is presented in brief. The methods and results of checking of the G dependence on the nature of substance (checking of the equivalence principle), G dependepce on distance (checking of Newton gravity law) and time (cosmological experiments) are presented. It is pointed out that all performed experiments don't give any reasons to have doubts in G constancy in space and time and G independence on the nature of the substance

  2. Photodissociation constant of NO2

    International Nuclear Information System (INIS)

    Nootebos, M.A.; Bange, P.

    1992-01-01

    The velocity of the dissociation of NO 2 into ozone and NO mainly depends on the ultraviolet sunlight quantity, and with that the cloudiness. A correct value for this reaction constant is important for the accurate modelling of O 3 - and NO 2 -concentrations in plumes of electric power plants, in particular in the case of determination of the amount of photochemical summer smog. An advanced signal processing method (deconvolution, correlation) was applied on the measurements. The measurements were carried out from aeroplanes

  3. Knowledge management (KM) processes in organizations theoretical foundations and practice

    CERN Document Server

    McInerney, Claire R

    2011-01-01

    Knowledge Management (KM) is an effort to increase useful knowledge in the organization. It is a natural outgrowth of late twentieth century movements to make organizational management and operations more effective, of higher quality, and more responsive to constituents in a rapidly changing global environment. This document traces the evolution of KM in organizations, summarizing the most influential research and literature in the field. It also presents an overview of selected common and current practices in knowledge management, including the relationship between knowledge management and de

  4. Evaluation of triggering schemes for KM3NeT

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, T., E-mail: Thomas.Seitz@physik.uni-erlangen.de [Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Herold, B., E-mail: Bjoern.Herold@physik.uni-erlangen.de [Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany); Shanidze, R., E-mail: shanidze@physik.uni-erlangen.de [Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen (Germany)

    2013-10-11

    The future neutrino telescope KM3NeT, to be built in the Mediterranean Sea, will be the largest of its kind. It will include nearly two hundred thousand photomultiplier tubes (PMT) mounted in multi-PMT digital optical modules (DOM). The dominant source of the PMT signals is decays of {sup 40}K and marine fauna bioluminescence. Selection of neutrino and muon events from this continuous optical background signals requires the implementation of fast and efficient triggers. Various schemes for the filtering of background data and the selection of neutrino and muon events were evaluated for the KM3NeT telescope using Monte Carlo simulations.

  5. Fine-structure constant: Is it really a constant

    International Nuclear Information System (INIS)

    Bekenstein, J.D.

    1982-01-01

    It is often claimed that the fine-structure ''constant'' α is shown to be strictly constant in time by a variety of astronomical and geophysical results. These constrain its fractional rate of change alpha-dot/α to at least some orders of magnitude below the Hubble rate H 0 . We argue that the conclusion is not as straightforward as claimed since there are good physical reasons to expect alpha-dot/α 0 . We propose to decide the issue by constructing a framework for a variability based on very general assumptions: covariance, gauge invariance, causality, and time-reversal invariance of electromagnetism, as well as the idea that the Planck-Wheeler length (10 -33 cm) is the shortest scale allowable in any theory. The framework endows α with well-defined dynamics, and entails a modification of Maxwell electrodynamics. It proves very difficult to rule it out with purely electromagnetic experiments. In a cosmological setting, the framework predicts an alpha-dot/α which can be compatible with the astronomical constraints; hence, these are too insensitive to rule out α variability. There is marginal conflict with the geophysical constraints: however, no firm decision is possible because of uncertainty about various cosmological parameters. By contrast the framework's predictions for spatial gradients of α are in fatal conflict with the results of the Eoetvoes-Dicke-Braginsky experiments. Hence these tests of the equivalence principle rule out with confidence spacetime variability of α at any level

  6. The 27-km circular path of the LHC tunnel

    CERN Multimedia

    AC-DI-MM

    1994-01-01

    This aerial view of the CERN site shows the path of the 27-km circumference tunnel that housed the LEP accelerator and now contains the accelerator for CERN's new flagship project, the LHC. The ring stretches from Geneva airport, which can be seen on the lower left, to the French countryside.

  7. 40km tunnel will try to unravel secrets of universe

    CERN Multimedia

    Connor, Steve

    2004-01-01

    An international panel of particle physicists has decided that the high-nergy linera collider will use revolutionary superconducting technology to shed light on the origin and nature of the universe. The collider will be housed in a dead-straight tunnel up to 40km long (1 page)

  8. Gravity wave vertical energy flux at 95 km

    Science.gov (United States)

    Jacob, P. G.; Jacka, F.

    1985-01-01

    A three-field photometer (3FP) located at Mt. Torrens near Adelaide, is capable of monitoring different airglow emissions from three spaced fields in the sky. A wheel containing up to six different narrow bandpass interference filters can be rotated, allowing each of the filters to be sequentially placed into each of the three fields. The airglow emission of interest is the 557.7 nm line which has an intensity maximum at 95 km. Each circular field of view is located at the apexes of an equilateral triangle centered on zenith with diameters of 5 km and field separations of 13 km when projected to the 95-km level. The sampling period was 30 seconds and typical data lengths were between 7 and 8 hours. The analysis and results from the interaction of gravity waves on the 557.7 nm emission layer are derived using an atmospheric model similar to that proposed by Hines (1960) where the atmosphere is assumed isothermal and perturbations caused by gravity waves are small and adiabatic, therefore, resulting in linearized equations of motion. In the absence of waves, the atmosphere is also considered stationary. Thirteen nights of quality data from January 1983 to October 1984, covering all seasons, are used in this analysis.

  9. Chandra Independently Determines Hubble Constant

    Science.gov (United States)

    2006-08-01

    A critically important number that specifies the expansion rate of the Universe, the so-called Hubble constant, has been independently determined using NASA's Chandra X-ray Observatory. This new value matches recent measurements using other methods and extends their validity to greater distances, thus allowing astronomers to probe earlier epochs in the evolution of the Universe. "The reason this result is so significant is that we need the Hubble constant to tell us the size of the Universe, its age, and how much matter it contains," said Max Bonamente from the University of Alabama in Huntsville and NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala., lead author on the paper describing the results. "Astronomers absolutely need to trust this number because we use it for countless calculations." Illustration of Sunyaev-Zeldovich Effect Illustration of Sunyaev-Zeldovich Effect The Hubble constant is calculated by measuring the speed at which objects are moving away from us and dividing by their distance. Most of the previous attempts to determine the Hubble constant have involved using a multi-step, or distance ladder, approach in which the distance to nearby galaxies is used as the basis for determining greater distances. The most common approach has been to use a well-studied type of pulsating star known as a Cepheid variable, in conjunction with more distant supernovae to trace distances across the Universe. Scientists using this method and observations from the Hubble Space Telescope were able to measure the Hubble constant to within 10%. However, only independent checks would give them the confidence they desired, considering that much of our understanding of the Universe hangs in the balance. Chandra X-ray Image of MACS J1149.5+223 Chandra X-ray Image of MACS J1149.5+223 By combining X-ray data from Chandra with radio observations of galaxy clusters, the team determined the distances to 38 galaxy clusters ranging from 1.4 billion to 9.3 billion

  10. Cryptography in constant parallel time

    CERN Document Server

    Applebaum, Benny

    2013-01-01

    Locally computable (NC0) functions are 'simple' functions for which every bit of the output can be computed by reading a small number of bits of their input. The study of locally computable cryptography attempts to construct cryptographic functions that achieve this strong notion of simplicity and simultaneously provide a high level of security. Such constructions are highly parallelizable and they can be realized by Boolean circuits of constant depth.This book establishes, for the first time, the possibility of local implementations for many basic cryptographic primitives such as one-way func

  11. Low power constant fraction discriminator

    International Nuclear Information System (INIS)

    Krishnan, Shanti; Raut, S.M.; Mukhopadhyay, P.K.

    2001-01-01

    This paper describes the design of a low power ultrafast constant fraction discriminator, which significantly reduces the power consumption. A conventional fast discriminator consumes about 1250 MW of power whereas this low power version consumes about 440 MW. In a multi detector system, where the number of discriminators is very large, reduction of power is of utmost importance. This low power discriminator is being designed for GRACE (Gamma Ray Atmospheric Cerenkov Experiments) telescope where 1000 channels of discriminators are required. A novel method of decreasing power consumption has been described. (author)

  12. Can coupling constants be related

    International Nuclear Information System (INIS)

    Nandi, Satyanarayan; Ng, Wing-Chiu.

    1978-06-01

    We analyze the conditions under which several coupling constants in field theory can be related to each other. When the relation is independent of the renormalization point, the relation between any g and g' must satisfy a differential equation as follows from the renormalization group equations. Using this differential equation, we investigate the criteria for the feasibility of a power-series relation for various theories, especially the Weinberg-Salam type (including Higgs bosons) with an arbitrary number of quark and lepton flavors. (orig./WL) [de

  13. Exact constants in approximation theory

    CERN Document Server

    Korneichuk, N

    1991-01-01

    This book is intended as a self-contained introduction for non-specialists, or as a reference work for experts, to the particular area of approximation theory that is concerned with exact constants. The results apply mainly to extremal problems in approximation theory, which in turn are closely related to numerical analysis and optimization. The book encompasses a wide range of questions and problems: best approximation by polynomials and splines; linear approximation methods, such as spline-approximation; optimal reconstruction of functions and linear functionals. Many of the results are base

  14. Hydrodynamic constants from cosmic censorship

    International Nuclear Information System (INIS)

    Nakamura, Shin

    2008-01-01

    We study a gravity dual of Bjorken flow of N=4 SYM-theory plasma. We point out that the cosmic censorship hypothesis may explain why the regularity of the dual geometry constrains the hydrodynamic constants. We also investigate the apparent horizon of the dual geometry. We find that the dual geometry constructed on Fefferman-Graham (FG) coordinates is not appropriate for examination of the apparent horizon since the coordinates do not cover the trapped region. However, the preliminary analysis on FG coordinates suggests that the location of the apparent horizon is very sensitive to the hydrodynamic parameters. (author)

  15. Relaxing a large cosmological constant

    International Nuclear Information System (INIS)

    Bauer, Florian; Sola, Joan; Stefancic, Hrvoje

    2009-01-01

    The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times, it has been rephrased as the dark energy (DE) problem in order to encompass a wider spectrum of possibilities. It is, in any case, a polyhedric puzzle with many faces, including the cosmic coincidence problem, i.e. why the density of matter ρ m is presently so close to the CC density ρ Λ . However, the oldest, toughest and most intriguing face of this polyhedron is the big CC problem, namely why the measured value of ρ Λ at present is so small as compared to any typical density scale existing in high energy physics, especially taking into account the many phase transitions that our Universe has undergone since the early times, including inflation. In this Letter, we propose to extend the field equations of General Relativity by including a class of invariant terms that automatically relax the value of the CC irrespective of the initial size of the vacuum energy in the early epochs. We show that, at late times, the Universe enters an eternal de Sitter stage mimicking a tiny positive cosmological constant. Thus, these models could be able to solve the big CC problem without fine-tuning and have also a bearing on the cosmic coincidence problem. Remarkably, they mimic the ΛCDM model to a large extent, but they still leave some characteristic imprints that should be testable in the next generation of experiments.

  16. Formas estructurales de fuerza constante

    Directory of Open Access Journals (Sweden)

    Zalewski, Waclaw

    1963-05-01

    Full Text Available The author seeks to prove the need to obtain the most essential form in the various types of structures by applying a number of rational principles, of which the constant stress principle is one of the most decisive. The structural form should be a logical consequence of all its functional circumstances, and this requires a clear understanding of the general behaviour of each part of the structure, and also of the main stresses which operate on it, considered as a unitary whole. To complete his theoretical argument, the author gives some examples, in the design of which the criterion of constant stress has been adopted. The author considers the various aspects which are involved in obtaining a structural design that satisfies given functional and aesthetic requirements. In doing so he refers to his personal experience within Poland, and infers technical principles of general validity which should determine the rational design of the form, as an integrated aspect of the structural pattern. The projects which illustrate this paper are Polish designs of undoubted constructive significance, in which the principle of constant stress has been applied. Finally the author condenses his whole theory in a simple and straightforward practical formula, which should be followed if a truly rational form is to be achieved: the constancy of stress in the various structural elements.El autor se esfuerza en mostrar la necesidad de llegar a la forma real en las distintas estructuras siguiendo una serie de principios racionales, entre los que domina el criterio de la fuerza constante. La forma ha de ser una consecuencia lógica en todos sus aspectos, y esto exige un claro conocimiento del comportamiento general de cada una de las partes de la estructura, y de los esfuerzos generales que dominan en la misma al considerarla como un todo. Para completar la exposición de orden teórico, el autor presenta algunos ejemplos en cuyo proyecto se ha seguido el criterio de

  17. Investigation into constant envelope orthogonal frequency division multiplexing for polarization-division multiplexing coherent optical communication

    Science.gov (United States)

    Li, Yupeng; Ding, Ding

    2017-09-01

    Benefiting from the high spectral efficiency and low peak-to-average power ratio, constant envelope orthogonal frequency division multiplexing (OFDM) is a promising technique in coherent optical communication. Polarization-division multiplexing (PDM) has been employed as an effective way to double the transmission capacity in the commercial 100 Gb/s PDM-QPSK system. We investigated constant envelope OFDM together with PDM. Simulation results show that the acceptable maximum launch power into the fiber improves 10 and 6 dB for 80- and 320-km transmission, respectively (compared with the conventional PDM OFDM system). The maximum reachable distance of the constant envelope OFDM system is able to reach 800 km, and even 1200 km is reachable if an ideal erbium doped fiber amplifier is employed.

  18. Remote (250 km Fiber Bragg Grating Multiplexing System

    Directory of Open Access Journals (Sweden)

    Manuel Lopez-Amo

    2011-09-01

    Full Text Available We propose and demonstrate two ultra-long range fiber Bragg grating (FBG sensor interrogation systems. In the first approach four FBGs are located 200 km from the monitoring station and a signal to noise ratio of 20 dB is obtained. The second improved version is able to detect the four multiplexed FBGs placed 250 km away, offering a signal to noise ratio of 6–8 dB. Consequently, this last system represents the longest range FBG sensor system reported so far that includes fiber sensor multiplexing capability. Both simple systems are based on a wavelength swept laser to scan the reflection spectra of the FBGs, and they are composed by two identical-lengths optical paths: the first one intended to launch the amplified laser signal by means of Raman amplification and the other one is employed to guide the reflection signal to the reception system.

  19. Magical properties of a 2540 km baseline superbeam experiment

    International Nuclear Information System (INIS)

    Raut, Sushant K.; Singh, Ravi Shanker; Uma Sankar, S.

    2011-01-01

    Lack of any information on the CP violating phase δ CP weakens our ability to determine neutrino mass hierarchy. Magic baseline of 7500 km was proposed to overcome this problem. However, to obtain large enough fluxes, at this very long baseline, one needs new techniques of generating high intensity neutrino beams. In this Letter, we highlight the magical properties of a 2540 km baseline. At such a baseline, using a narrow band neutrino superbeam whose no oscillation event rate peaks around the energy 3.5 GeV, we can determine neutrino mass hierarchy independently of the CP phase. For sin 2 2θ 13 ≥0.05, a very modest exposure of 10 Kiloton-years is sufficient to determine the hierarchy. For 0.02≤sin 2 2θ 13 ≤0.05, an exposure of about 100 Kiloton-years is needed.

  20. Enterprise KM System: IT based Tool for Nuclear Malaysia

    International Nuclear Information System (INIS)

    Mohamad Safuan Sulaiman; Siti Nurbahyah Hamdan; Mohd Dzul Aiman Aslan

    2014-01-01

    Implementation of right and suitable tool for enterprise Knowledge Management (KM) system to an organization is not an easy task. Everything needs to be taken into account before its implementation come true. One of them is to ensure full cooperation is given by the whole entire organization to succeed the knowledge sharing culture utilizing the tool. From selection of potential tools until the implementation and deployment strategies, these shall be thoroughly and carefully organized. A study of choosing the suitable tools and those strategies has been done in Nuclear Malaysia as resulted from Process Oriented Knowledge Management (POKM) project. As far as enterprise KM system is concerned, Microsoft Share Point technology is one of the potential tools in this context. This paper articulates approach and methodology of choosing the technology including its planning, deployment and implementation strategies. (author)

  1. Hypervelocity launch capabilities to over 10 km/s

    International Nuclear Information System (INIS)

    Chhabildas, L.C.

    1991-01-01

    Very high pressure and acceleration is necessary to launch flier plates to hypervelocities. In addition, the high pressure loading must be uniform, structured, and shockless, i.e., time-dependent to prevent the flier plate from either fracturing or melting. In this paper, a novel technique is described which allows the use of megabar level loading pressures, and 10 9 g acceleration to launch intact flier plates to velocities of 12.2 km/s. 32 refs., 2 figs

  2. Technical description of the Tansy Spectrometer, TANSY-KM5

    International Nuclear Information System (INIS)

    Grosshoeg, G.; Aronsson, D.; Hoek, M.; Rydz, R.; Norberg, L.; Urholm, L.

    1991-07-01

    The TANSY-KM5 neutron spectrometer is a system containing a lot of advanced electronic and mechanical components. The design of the system has been reported in two documents (CTH-RF--54 (INIS 17:10206) and CTH-RF--43 (INIS 14:797424)). The purpose of this documentation is to give a brief overview of the system as it is defined at the time of delivery

  3. Computerized radiation control system in the Chernobyl 30-km zone

    International Nuclear Information System (INIS)

    Vasil'chenko, D.L.; Pis'mak, A.D.; Livertovskij, G.P.; Chikhladze, V.S.

    1992-01-01

    Computerized radiation control system is intended for monitoring radiation in the zone of radiation-hazardous objects for providing nuclear power station services with current information on radiactive situation in the zone of observation and the doses of radiation taken by the personnel. Described are tasks and functions of the system, as well as its structure. It is noted that unique conditions of the Chernobyl' 30-km zone open up opportunities for experiments and testing new models of equipment. 2 figs

  4. Model evaluation for travel distances 30 to 140 km

    International Nuclear Information System (INIS)

    Pendergast, M.M.

    1978-01-01

    The assessment of environmental effects from industrial pollution for travel distances over 50 km has been made largely without verification of the models used. Recently the Savannah River Laboratory, in cooperation with the Air Resources Laboratory of NOAA, has compiled a data base capable of providing this important verification. The data consists of (1) hourly release rates of 85 Kr from 62 m stacks near the center of the Savannah River Plant (SRP), Aiken, SC; (2) turbulence quality meteorological data from seven 62 m towers at SRP and the 335 m WJBF-TV tower at Beech Island, SC, located 25 km from the center of the SRP; (3) National Weather Service surface and upper air observations including Bush Field Airport, Augusta, Ga., about 30 km from the center of SRP; (4) hourly estimates of the mixing depth obtained with an acoustic sounder located on the SRP; and (5) weekly and 10-hour averaged 85 Kr air concentrations at 13 sites surrounding the SRP at distances ranging between 30 and 143 km. An earlier report has shown that annual averaged air concentrations for 1975 agree with observed values at the 13 sites within a factor of two (Pendergast, 1977). This report presents more detailed results based upon 10-hour averaged air concentrations. The models evaluated were variations of the stability wind-rose model and a segmented plume model. The meteorological models depend upon several key input variables: (1) stability category, (2) sigma/sub y/ and sigma/sub z/ curves, (3) wind velocity, and (4) mixing depth. Each of these key variables can be estimated by a variety of methods averaging processes. Several of the more commonly used methods for estimating the four key variables were evaluated using calculated and measured 85 Kr air concentrations. Estimates of error were obtained for monthly and 10-hour sampling times

  5. Activation of molybdenite concentrate of KM-4 index mark

    International Nuclear Information System (INIS)

    Bogomolov, A.M.; Mitskevich, A.A.; Shuvaev, A.P.

    1991-01-01

    A study was made on the effect of mechanical activation in DU-73 disintegrator on structural characteristics, dissolution rate and leaching degree of molybdenite in KM-4 concentrated. The following facts were established in experiments: high amorphization degree of basal planes (plate surfaces) ∼ 80%, increase of oxidation degree by 35% on the average. All this testify to the fact, that oxidation reaction in activated molybdenite proceeds both on plate edges and on broken basal planes

  6. Venous hemogasometry of equines finalists in 90 km endurance races

    Directory of Open Access Journals (Sweden)

    Cinthia B.S. Dumont

    2014-06-01

    Full Text Available Front of exercise, the organic systems may suffer water-electrolyte and acid-base imbalances, particularly in the case of blood gases, demonstrating variations from different causes, whether respiratory and/or metabolic. Understanding the physiological adaptations to exercise is essential in the search for the optimum performance. In this way, this study measured the venous blood gases (pO2, pCO2, as well as the oxygen saturation (SatO2 in healthy equines, Arabian horses finalists in 90km endurance races. A total of fourteen Arabian horses were evaluated, nine males and five females, between six and 12 years old, finalists in 90km endurance races. There was a significant reduction in pO2, pCO2 and SatO2 after the exercise, however, the values remained within the normality range, and did not change the athletic performance of the animals, indicating a temporary alteration, assuming thus a character of physiological response to the exercise performed. The equines, finalists in 90 Km endurance races, demonstrated efficient ventilatory process, without any alterations in the athletic performance, being adapted to the type of exercise imposed.

  7. Constant Proportion Debt Obligations (CPDOs)

    DEFF Research Database (Denmark)

    Cont, Rama; Jessen, Cathrine

    2012-01-01

    be made arbitrarily small—and thus the credit rating arbitrarily high—by increasing leverage, but the ratings obtained strongly depend on assumptions on the credit environment (high spread or low spread). More importantly, CPDO loss distributions are found to exhibit a wide range of tail risk measures......Constant Proportion Debt Obligations (CPDOs) are structured credit derivatives that generate high coupon payments by dynamically leveraging a position in an underlying portfolio of investment-grade index default swaps. CPDO coupons and principal notes received high initial credit ratings from...... the major rating agencies, based on complex models for the joint transition of ratings and spreads for all names in the underlying portfolio. We propose a parsimonious model for analysing the performance of CPDO strategies using a top-down approach that captures the essential risk factors of the CPDO. Our...

  8. Energy, stability and cosmological constant

    International Nuclear Information System (INIS)

    Deser, S.

    1982-01-01

    The definition of energy and its use in studying stability in general relativity are extended to the case when there is a nonvanishing cosmological constant Λ. Existence of energy is first demonstrated for any model (with arbitrary Λ). It is defined with respect to sets of solutions tending asymptotically to any background space possessing timelike Killing symmetry, and is both conserved and of flux integral form. When Λ O, small excitations about De Sitter space are stable inside the event horizon. Outside excitations can contribute negatively due to the Killing vector's flip at the horizon. This is a universal phenomenon associated with the possibility of Hawking radiation. Apart from this effect, the Λ>O theory appears to be stable, also at the semi-classical level. (author)

  9. Filament instability under constant loads

    Science.gov (United States)

    Monastra, A. G.; Carusela, M. F.; D’Angelo, M. V.; Bruno, L.

    2018-04-01

    Buckling of semi-flexible filaments appears in different systems and scales. Some examples are: fibers in geophysical applications, microtubules in the cytoplasm of eukaryotic cells and deformation of polymers freely suspended in a flow. In these examples, instabilities arise when a system’s parameter exceeds a critical value, being the Euler force the most known. However, the complete time evolution and wavelength of buckling processes are not fully understood. In this work we solve analytically the time evolution of a filament under a constant compressive force in the small amplitude approximation. This gives an insight into the variable force scenario in terms of normal modes. The evolution is highly sensitive to the initial configuration and to the magnitude of the compressive load. This model can be a suitable approach to many different real situations.

  10. Evolution of the solar 'constant'

    Energy Technology Data Exchange (ETDEWEB)

    Newman, M J

    1980-06-01

    Variations in solar luminosity over geological time are discussed in light of the effect of the solar constant on the evolution of life on earth. Consideration is given to long-term (5 - 7% in a billion years) increases in luminosity due to the conversion of hydrogen into helium in the solar interior, temporary enhancements to solar luminosity due to the accretion of matter from the interstellar medium at intervals on the order of 100 million years, and small-amplitude rapid fluctuations of luminosity due to the stochastic nature of convection on the solar surface. It is noted that encounters with dense interstellar clouds could have had serious consequences for life on earth due to the peaking of the accretion-induced luminosity variation at short wavelengths.

  11. Asympotics with positive cosmological constant

    Science.gov (United States)

    Bonga, Beatrice; Ashtekar, Abhay; Kesavan, Aruna

    2014-03-01

    Since observations to date imply that our universe has a positive cosmological constant, one needs an extension of the theory of isolated systems and gravitational radiation in full general relativity from the asymptotically flat to asymptotically de Sitter space-times. In current definitions, one mimics the boundary conditions used in asymptotically AdS context to conclude that the asymptotic symmetry group is the de Sitter group. However, these conditions severely restricts radiation and in fact rules out non-zero flux of energy, momentum and angular momentum carried by gravitational waves. Therefore, these formulations of asymptotically de Sitter space-times are uninteresting beyond non-radiative spacetimes. The situation is compared and contrasted with conserved charges and fluxes at null infinity in asymptotically flat space-times.

  12. 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.

  13. 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

  14. Glucose biosensing using glassy carbon electrode modified with polyhydroxy-C60, glucose oxidase and ionic-liquid.

    Science.gov (United States)

    Yang, Tian; Yang, Xiao-Lu; Zhang, Yu-Shuai; Xiao, BaoLin; Hong, Jun

    2014-01-01

    Direct electrochemistry of glucose oxidase (GOD) was achieved when an ionic liquid/GOD-Polyhydroxy-C60 functional membrane was confined on a glassy carbon electrode (GCE). The cyclic voltammograms (CVs) of the modified GCE showed a pair of redox peaks with a formal potential (E°') of - 329 ± 2 mV. The heterogeneous electron transfer constant (k(s)) was 1.43 s-1. The modified GCE response to glucose was linear in the range from 0.02 to 2.0 mM. The detection limit was 1 μM. The apparent Michaelis-Menten constant (K(m)(app)) was 1.45 mM.

  15. 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.

  16. The fundamental constants a mystery of physics

    CERN Document Server

    Fritzsch, Harald

    2009-01-01

    The speed of light, the fine structure constant, and Newton's constant of gravity — these are just three among the many physical constants that define our picture of the world. Where do they come from? Are they constant in time and across space? In this book, physicist and author Harald Fritzsch invites the reader to explore the mystery of the fundamental constants of physics in the company of Isaac Newton, Albert Einstein, and a modern-day physicist

  17. A constraint on the distance dependence of the gravitational constant

    International Nuclear Information System (INIS)

    Hut, P.

    1981-01-01

    Extended supergravity theories predict the existence of vector and scalar bosons, besides the gravitation, which in the static limit couple to the mass. An example is the gravitation, leading to antigravity. If these bosons have a small mass (approx. -4 eV), an observable Yukawa term would be present in the gravitational potential in the newtonian limit. This can be parametrized by a distance dependent effective gravitational constant G(γ). Defining G 0 = G (10 cm) and Gsub(e) = G (10 3 km), the comparison between theory and observations of the white dwarf Sirius B results in Gsub(c)/G 0 = 0.98 +- 0.08. (orig.)

  18. A nuclear data approach for the Hubble constant measurements

    Directory of Open Access Journals (Sweden)

    Pritychenko Boris

    2017-01-01

    Full Text Available An extraordinary number of Hubble constant measurements challenges physicists with selection of the best numerical value. The standard U.S. Nuclear Data Program (USNDP codes and procedures have been applied to resolve this issue. The nuclear data approach has produced the most probable or recommended Hubble constant value of 67.2(69 (km/sec/Mpc. This recommended value is based on the last 20 years of experimental research and includes contributions from different types of measurements. The present result implies (14.55 ± 1.51 × 109 years as a rough estimate for the age of the Universe. The complete list of recommended results is given and possible implications are discussed.

  19. Nitrous oxide production kinetics during nitrate reduction in river sediments.

    Science.gov (United States)

    Laverman, Anniet M; Garnier, Josette A; Mounier, Emmanuelle M; Roose-Amsaleg, Céline L

    2010-03-01

    A significant amount of nitrogen entering river basins is denitrified in riparian zones. The aim of this study was to evaluate the influence of nitrate and carbon concentrations on the kinetic parameters of nitrate reduction as well as nitrous oxide emissions in river sediments in a tributary of the Marne (the Seine basin, France). In order to determine these rates, we used flow-through reactors (FTRs) and slurry incubations; flow-through reactors allow determination of rates on intact sediment slices under controlled conditions compared to sediment homogenization in the often used slurry technique. Maximum nitrate reduction rates (R(m)) ranged between 3.0 and 7.1microg Ng(-1)h(-1), and affinity constant (K(m)) ranged from 7.4 to 30.7mg N-NO(3)(-)L(-1). These values were higher in slurry incubations with an R(m) of 37.9microg Ng(-1)h(-1) and a K(m) of 104mg N-NO(3)(-)L(-1). Nitrous oxide production rates did not follow Michaelis-Menten kinetics, and we deduced a rate constant with an average of 0.7 and 5.4ng Ng(-1)h(-1) for FTR and slurry experiments respectively. The addition of carbon (as acetate) showed that carbon was not limiting nitrate reduction rates in these sediments. Similar rates were obtained for FTR and slurries with carbon addition, confirming the hypothesis that homogenization increases rates due to release of and increasing access to carbon in slurries. Nitrous oxide production rates in FTR with carbon additions were low and represented less than 0.01% of the nitrate reduction rates and were even negligible in slurries. Maximum nitrate reduction rates revealed seasonality with high potential rates in fall and winter and low rates in late spring and summer. Under optimal conditions (anoxia, non-limiting nitrate and carbon), nitrous oxide emission rates were low, but significant (0.01% of the nitrate reduction rates). Copyright 2009 Elsevier Ltd. All rights reserved.

  20. Hidrólisis enzimática de residuos de la cosecha de caña de azúcar

    Directory of Open Access Journals (Sweden)

    Jairo G. Salcedo Mendoza

    2012-01-01

    Full Text Available Título en inglés: Hydrolysis Enzymatic of crop residues sugar cane Resumen: En esta investigación, se hidrolizó un sustrato deslignificado proveniente de residuos de la cosecha caña de azúcar  (hojas y cogollos usando un  preparado enzimático con 27.53 unidades de papel filtro (FPU, obtenido a partir de enzimas comerciales. La hidrólisis se llevó a cabo a un pH de 4.2 y una temperatura de 50 oC. Fueron analizados  modelos de inhibición por sustrato, glucosa e inhibición total por producto. Los resultados mostraron que los modelos que mejor se ajustan a los datos experimentales, son los modelos de inhibición competitiva por glucosa, con una constante de Michaelis (Km de 20.37 g/L,  velocidad máxima (Vmax 39 g/L h y una constante de inhibición  (ki de 0.442. En el caso que las relaciones  enzima – Sustrato (E/S sean mayores  de 0.5, se puede aplicar el modelo cinético de Michaelis-Menten. Palabras clave: Inhibición; modelos cinéticos; hojas y cogollos; coctel de enzimas Abstract: In this research, a delignified substrate from crops residues sugar cane residues (leaves and top cane was hydrolyzed using an enzyme preparation with 27.53 FPU. This enzyme was obtained from trade. Hydrolysis was carried out to pH of 4.2 and a temperature of 50 oC. Models of inhibition models substrate, glucose and total inhibition product was analyzed. The results showed that models that best fit the data experimental was the models competitive glucose inhibition (Km= 20.37, Vmax=39 and ki= 0.442. In the event that E/S is above 0.5, can applied kinetic models of Michaelis – Menten. Keywords: Inhibition; kinetic models; leaves and tops cane; enzyme cocktail.

  1. Three-dimensional spatial structures of solar wind turbulence from 10 000-km to 100-km scales

    Directory of Open Access Journals (Sweden)

    Y. Narita

    2011-10-01

    Full Text Available Using the four Cluster spacecraft, we have determined the three-dimensional wave-vector spectra of fluctuating magnetic fields in the solar wind. Three different solar wind intervals of Cluster data are investigated for this purpose, representing three different spatial scales: 10 000 km, 1000 km, and 100 km. The spectra are determined using the wave telescope technique (k-filtering technique without assuming the validity of Taylor's frozen-in-flow hypothesis nor are any assumptions made as to the symmetry properties of the fluctuations. We find that the spectra are anisotropic on all the three scales and the power is extended primarily in the directions perpendicular to the mean magnetic field, as might be expected of two-dimensional turbulence, however, the analyzed fluctuations are not axisymmetric. The lack of axisymmetry invalidates some earlier techniques using single spacecraft observations that were used to estimate the percentage of magnetic energy residing in quasi-two-dimensional power. However, the dominance of two-dimensional turbulence is consistent with the relatively long mean free paths of cosmic rays in observed in the heliosphere. On the other hand, the spectra also exhibit secondary extended structures oblique from the mean magnetic field direction. We discuss possible origins of anisotropy and asymmetry of solar wind turbulence spectra.

  2. Comparison of dopamine kinetics in the larval Drosophila ventral nerve cord and protocerebrum with improved optogenetic stimulation.

    Science.gov (United States)

    Privman, Eve; Venton, B Jill

    2015-11-01

    Dopamine release and uptake have been studied in the Drosophila larval ventral nerve cord (VNC) using optogenetics to stimulate endogenous release. However, other areas of the central nervous system remain uncharacterized. Here, we compare dopamine release in the VNC and protocerebrum of larval Drosophila. Stimulations were performed with CsChrimson, a new, improved, red light-activated channelrhodopsin. In both regions, dopamine release was observed after only a single, 4 ms duration light pulse. Michaelis-Menten modeling was used to understand release and uptake parameters for dopamine. The amount of dopamine released ([DA]p ) on the first stimulation pulse is higher than the average [DA]p released from subsequent pulses. The initial and average amount of dopamine released per stimulation pulse is smaller in the protocerebrum than in the VNC. The average Vmax of 0.08 μM/s in the protocerebrum was significantly higher than the Vmax of 0.05 μM/s in the VNC. The average Km of 0.11 μM in the protocerebrum was not significantly different from the Km of 0.10 μM in the VNC. When the competitive dopamine transporter (DAT) inhibitor nisoxetine was applied, the Km increased significantly in both regions while Vmax stayed the same. This work demonstrates regional differences in dopamine release and uptake kinetics, indicating important variation in the amount of dopamine available for neurotransmission and neuromodulation. We use a new optogenetic tool, red light activated CsChrimson, to stimulate the release of dopamine in the ventral nerve cord and medial protocerebrum of the larval Drosophila central nervous system. We monitored extracellular dopamine by fast scan cyclic voltammetry and used Michaelis-Menten modeling to probe the regulation of extracellular dopamine, discovering important similarities and differences in these two regions. © 2015 International Society for Neurochemistry.

  3. Mapping the global land surface using 1 km AVHRR data

    Science.gov (United States)

    Lauer, D.T.; Eidenshink, J.C.

    1998-01-01

    The scientific requirements for mapping the global land surface using 1 km advanced very high resolution radiometer (AVHRR) data have been set forth by the U.S. Global Change Research Program; the International Geosphere Biosphere Programme (IGBP); The United Nations; the National Oceanic and Atmospheric Administration (NOAA); the Committee on Earth Observations Satellites; and the National Aeronautics and Space Administration (NASA) mission to planet Earth (MTPE) program. Mapping the global land surface using 1 km AVHRR data is an international effort to acquire, archive, process, and distribute 1 km AVHRR data to meet the needs of the international science community. A network of AVHRR receiving stations, along with data recorded by NOAA, has been acquiring daily global land coverage since April 1, 1992. A data set of over 70,000 AVHRR images is archived and distributed by the United States Geological Survey (USGS) EROS Data Center, and the European Space Agency. Under the guidance of the IGBP, processing standards have been developed for calibration, atmospheric correction, geometric registration, and the production of global 10-day maximum normalized difference vegetation index (NDVI) composites. The major uses of the composites are for the study of surface vegetation condition, mapping land cover, and deriving biophysical characteristics of terrestrial ecosystems. A time-series of 54 10-day global vegetation index composites for the period of April 1, 1992 through September 1993 has been produced. The production of a time-series of 33 10-day global vegetation index composites using NOAA-14 data for the period of February 1, 1995 through December 31, 1995 is underway. The data products are available from the USGS, in cooperation with NASA's MTPE program and other international organizations.

  4. Arrhenius Rate: constant volume burn

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-12-06

    A constant volume burn occurs for an idealized initial state in which a large volume of reactants at rest is suddenly raised to a high temperature and begins to burn. Due to the uniform spatial state, there is no fluid motion and no heat conduction. This reduces the time evolu tion to an ODE for the reaction progress variable. With an Arrhenius reaction rate, two characteristics of thermal ignition are illustrated: induction time and thermal runaway. The Frank-Kamenetskii approximation then leads to a simple expression for the adiabatic induction time. For a first order reaction, the analytic solution is derived and used to illustrate the effect of varying the activation temperature; in particular, on the induction time. In general, the ODE can be solved numerically. This is used to illustrate the effect of varying the reaction order. We note that for a first order reaction, the time evolution of the reaction progress variable has an exponential tail. In contrast, for a reaction order less than one, the reaction completes in a nite time. The reaction order also affects the induction time.

  5. The relational database system of KM3NeT

    Science.gov (United States)

    Albert, Arnauld; Bozza, Cristiano

    2016-04-01

    The KM3NeT Collaboration is building a new generation of neutrino telescopes in the Mediterranean Sea. For these telescopes, a relational database is designed and implemented for several purposes, such as the centralised management of accounts, the storage of all documentation about components and the status of the detector and information about slow control and calibration data. It also contains information useful during the construction and the data acquisition phases. Highlights in the database schema, storage and management are discussed along with design choices that have impact on performances. In most cases, the database is not accessed directly by applications, but via a custom designed Web application server.

  6. Gate-keeper module for TANSY-KM5

    International Nuclear Information System (INIS)

    Rydz, R.; Norberg, L.; Urholm, L.; Grosshoeg, G.

    1991-01-01

    The purpose of the Gate-keeper is the control of the RDCs, the ADCs, and the constant fraction discriminator. The Gate-keeper synchronizes the units and ensures that the data taking is clean and not intermixed with other events. There are six Gate-Keepers in the system, one for each proton detector. All input circuits are designed to accept TTL as well as negative NIM signals. The output is 50 ohm TTL or negative NIM as defined by internal jumpers

  7. Nighttime ionization by energetic particles at Wallops Island in the altitude region 120 to 200 km

    Science.gov (United States)

    Voss, H. D.; Smith, L. G.

    1979-01-01

    Five Nike Apache rockets, each including an energetic particle spectrometer and an electron density-electron temperature experiment, have been launched from Wallops Island (L = 2.6) near midnight under varying geomagnetic conditions. On the most recent of these (5 January 1978) an additional spectrometer with a broom magnet, and a 391.4 nm photometer were flown. The data from this flight indicate that the energetic particle flux consists predominantly of protons, neutral hydrogen and possibly other energetic nuclei. The energy spectrum becomes much softer and the flux more intense with increasing Kp for 10-100 keV. The pitch angle distribution at 180 km is asymmetrical with a peak at 90 deg indicating that the majority of particles are near their mirroring altitude. Ionization rates are calculated based on the measured energy spectrum and mirror height distribution. The resulting ionization rate profile is found to be nearly constant with altitude in the region 120 to 200 km. The measured energetic particle flux and calculated ionization rate from the five flights are found to vary with magnetic activity (based on the Kp and Dst indexes) in the same way as the independently derived ionization rates deduced from the electron density profile.

  8. Characterization of the anion sensitive ATPase in intact vacuoles of Kalanchoe diagremontiana

    Energy Technology Data Exchange (ETDEWEB)

    Kobza, J.; Uribe, E.G.

    1986-04-01

    A method for the isolation of intact vacuoles from K. daigremontiana was developed which produced high yields of relatively pure vacuoles as determined by marker enzyme contamination. Upon isolation, the vacuoles were stabilized by the inclusion of 5% (w/v) ficoll. Enzyme activity was insensitive to vanadate and azide but was strongly inhibited by DCCD. Enzyme activity was strictly dependent on the inclusion of Mg/sup 2 +/ and was stimulated by anions as depicted by the series, NO/sub 3//sup -/ < Br/sup -/ < SO/sub 4//sup -/ < HCO/sub 3//sup -/ < Cl/sup -/. It was found that in intact vacuoles the ATPase activity was stimulated by phosphate to a level equivalent to that found with the chloride. The enzyme exhibited Michaelis-Menten kinetics with a Km for Mg-ATP complex of 0.51 mM.

  9. Projected Population Proximity Indices (30km for 2005, 2030 & 2050

    Directory of Open Access Journals (Sweden)

    Neil S. Alexander

    2013-07-01

    Full Text Available This data package includes nine population proximity index layers for 2005, 2030 and 2050, for rural, urban and total populations.  The layers are distributed as 1km GeoTIFFs and GeoJPGss at 1km. The aim of these layers is to describe the population which may be likely to visit a specific locality where access is determined by Euclidean distance. By using the layers alongside other geographic datasets relating to disease risk it may help identify where people may come into contact with a disease.  Human population layers are often used in models to identify risk areas where humans and viruses interact, however most pathogens are not restricted to areas of human habitation: many are found in lesser populated areas such as forests.  This dataset will help identify less populated areas that may well still receive high visitor numbers. The layers have been projected to 2030 and 2050 to enable projections of human/disease interfaces in the medium-term which are required to inform policy makers at country and continental level. Urban and rural populations have been separated into individual layers as in some cases it is useful to distinguish between the behaviour and associated risks attributed to the different population segments.  There may be a different risk of contacting diseases in rural habitats for rural workers than for than urban visitors.

  10. Capacitive Cells for Dielectric Constant Measurement

    Science.gov (United States)

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

    A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

  11. The Dielectric Constant of Lubrication Oils

    National Research Council Canada - National Science Library

    Carey, A

    1998-01-01

    The values of the dielectric constant of simple molecules is discussed first, along with the relationship between the dielectric constant and other physical properties such as boiling point, melting...

  12. Globally Coupled Chaotic Maps with Constant Force

    International Nuclear Information System (INIS)

    Li Jinghui

    2008-01-01

    We investigate the motion of the globally coupled maps (logistic map) with a constant force. It is shown that the constant force can cause multi-synchronization for the globally coupled chaotic maps studied by us.

  13. STABILITY CONSTANT OF THE TRISGLYCINATO METAL ...

    African Journals Online (AJOL)

    DR. AMINU

    overall stability constants of the complexes were found to be similar. Keywords: Glycinato, titration ... +. −. = 1 where Ka = dissociation constant of the amino acid. [ ]+. H = concentration of the .... Synthesis and techniques in inorganic chemistry.

  14. In vitro modulation of cytochrome P450 reductase supported indoleamine 2,3-dioxygenase activity by allosteric effectors cytochrome b(5) and methylene blue.

    Science.gov (United States)

    Pearson, Josh T; Siu, Sophia; Meininger, David P; Wienkers, Larry C; Rock, Dan A

    2010-03-30

    Indoleamine 2,3-dioxygenase (IDO) is a heme-containing dioxygenase involved in the degradation of several indoleamine derivatives and has been indicated as an immunosuppressive. IDO is an attractive target for therapeutic intervention in diseases which are known to capitalize on immune suppression, including cancer, HIV, and inflammatory diseases. Conventionally, IDO activity is measured through chemical reduction by the addition of ascorbate and methylene blue. Identification of potential coenzymes involved in the reduction of IDO in vivo should improve in vitro reconstitution systems used to identify potential IDO inhibitors. In this study we show that NADPH-cytochrome P450 reductase (CPR) is capable of supporting IDO activity in vitro and that oxidation of l-Trp follows substrate inhibition kinetics (k(cat) = 0.89 +/- 0.04 s(-1), K(m) = 0.72 +/- 0.15 microM, and K(i) = 9.4 +/- 2.0 microM). Addition of cytochrome b(5) to CPR-supported l-Trp incubations results in modulation from substrate inhibition to sigmoidal kinetics (k(cat) = 1.7 +/- 0.3 s(-1), K(m) = 1.5 +/- 0.9 microM, and K(i) = 1.9 +/- 0.3). CPR-supported d-Trp oxidations (+/-cytochrome b(5)) exhibit Michaelis-Menten kinetics. Addition of methylene blue (minus ascorbate) to CPR-supported reactions resulted in inhibition of d-Trp turnover and modulation of l-Trp kinetics from allosteric to Michaelis-Menten with a concurrent decrease in substrate affinity for IDO. Our data indicate that CPR is capable of supporting IDO activity in vitro and oxidation of tryptophan by IDO displays substrate stereochemistry dependent atypical kinetics which can be modulated by the addition of cytochrome b(5).

  15. A glassy carbon electrode modified with a composite consisting of reduced graphene oxide, zinc oxide and silver nanoparticles in a chitosan matrix for studying the direct electron transfer of glucose oxidase and for enzymatic sensing of glucose

    International Nuclear Information System (INIS)

    Li, Zhenjiang; Sheng, Liying; Xie, Cuicui; Meng, Alan; Zhao, Kun

    2016-01-01

    The authors describe the fabrication of a nanocomposite consisting of reduced graphene oxide, zinc oxide and silver nanoparticles by microwave-assisted synthesis. The composite was further reduced in-situ with hydrazine hydrate and then placed, along with the enzyme glucose oxidase, on a glassy carbon electrode. The synergistic effect of the materials employed in the nanocomposite result in excellent electrocatalytic activity. The Michaelis-Menten constant of the adsorbed GOx is 0.25 mM, implying a remarkable affinity of the GOx for glucose. The amperometric response of the modified GCE is linearly proportional to the concentration of glucose in 0.1 to 12.0 mM concentration range, and the detection limit is 10.6 µM. The biosensor is highly selective, well reproducible and stable. (author)

  16. Simple method for preparing glucose biosensor based on in-situ polypyrrole cross-linked chitosan/glucose oxidase/gold bionanocomposite film.

    Science.gov (United States)

    Şenel, Mehmet

    2015-03-01

    A film of chitosan-polypyrrole-gold nanoparticles was fabricated by in-situ chemical synthesis method and its application in glucose biosensor was investigated. The obtained biosensor exhibited a high and reproducible sensitivity of 0.58μA/mM, response time ~4s, linear dynamic range from 1 to 20mM, correlation coefficient of R(2)=0.9981, and limit of detection (LOD), based on S/N ratio (S/N=3) of 0.068mM. A value of 1.83mM for the apparent Michaelis-Menten constant was obtained. The resulting bio-nanocomposite provided a suitable environment for the enzyme to retain its bioactivity at considerably extreme conditions, and the decorated gold nanoparticles in the bio-nanocomposite offer good affinity to enzyme. Copyright © 2014. Published by Elsevier B.V.

  17. 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)

  18. Characteristics of 36C103- influx into nitrate reductase deficient mutant E1 pisum sativum seedlings: evidence for restricted ''induction'' by nitrate compared with wild type

    International Nuclear Information System (INIS)

    Deane-Drummond, C.E.; Jacobsen, E.

    1986-01-01

    The characteristics of nitrate uptake into seedlings of Pisum sativum L. cv. Rondo mutant E 1 defective for nitrate reductase (NR) and of its parent variety Rondo have been investigated using 36 C10 3 - as an analogue for nitrate. The apparent Michaelis Menten constants (K m ) for 36 ClO 3 - influx measured over 10 min were similar for mutant E 1 and the wild type (Wt). There was a 28% increase in 36 C10 3 - into Wt seedlings following nitrate pretreatment but this was not found when mutant seedlings were used. N starvation increased 36 C10 3 - influx into both mutant and Wt seedlings, and the rate of cycling E/I was also enhanced to a similar extent. The results are discussed in terms of current ideas on the regulation of nitrate uptake and assimilation. (author)

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

    Science.gov (United States)

    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.

  20. Fabrication of a sulfite biosensor by the use of conducting polymer

    International Nuclear Information System (INIS)

    Hosseini, M.; Bahmani, B; Moztarzadeh, F.; Rabiee, M.

    2008-01-01

    In this research, an enzyme modified electrode has been produced during the electro polymerization of aniline through incorporation of Sulfite oxidase into a conducting polymer. Then the bioelectrochemical response of resulted sulfite biosensor was investigated at different experimental conditions. Study of the stability of the resulted sulfite biosensor revealed that formation of a passive film on the aluminum surface causes improved stability of the electro active films formed on the electrode surface. The bioelectrochemical response of the enzyme-modified electrode as a sulfite biosensor was investigated at different experimental conditions. The optimum p H and temperature were 8.5 and 35 d eg C , respectively. The apparent Michaelis-Menten constant and the activation energy of the enzyme catalyzed reaction were calculated

  1. Kinetic Studies on Trichoderna Viride Cellulase

    International Nuclear Information System (INIS)

    Saw Aung; Oo Aung; Aung Myint

    2002-02-01

    Studies on cellulase enzyme (EC 3.2.1.4), which catalyzes the hydrolysis of. cellulose to yield glucose, were made. Cellulase from a fungus source, Trichoderma viride was cultivated on Czapek's agar medium and enzyme production broth medium was employed for parameter tests. The microscopic examination and cellulase hydrolysis test on subcultured fungi were applied to confirm the T. viride species. A calibration curve for standard glucose was plotted by using visible spectroscopy. Dinitrosalicylic acid was used as enzyme reaction inhibitor and the colour intensity was measured in a UV-visible spectrophotometer at a λ max of 570 nm. The parameters such as optimum pH, optimum temperature, effect of substrate concentration, effect, of enzyme concentration, enzyme unit (EU), reaction order (n), maximum velocity (V max ), Michaelis-Menten constant (K m ) using various substrates, viz., carboxy methylcellulose, cotton fibre and filter paper determined. (author)

  2. Evidence of enzymatic catalysis of oxygen reduction on stainless steels under marine biofilm.

    Science.gov (United States)

    Faimali, Marco; Benedetti, Alessandro; Pavanello, Giovanni; Chelossi, Elisabetta; Wrubl, Federico; Mollica, Alfonso

    2011-04-01

    Cathodic current trends on stainless steel samples with different surface percentages covered by biofilm and potentiostatically polarized in natural seawater were studied under oxygen concentration changes, temperature increases, and additions of enzymic inhibitors to the solution. The results showed that on each surface fraction covered by biofilm the oxygen reduction kinetics resembled a reaction catalyzed by an immobilised enzyme with high oxygen affinity (apparent Michaelis-Menten dissociation constant close to K(O(2))(M)  ≈ 10 μM) and low activation energy (W ≈ 20 KJ mole(-1)). The proposed enzyme rapidly degraded when the temperature was increased above the ambient (half-life time of ∼1 day at 25°C, and of a few minutes at 50°C). Furthermore, when reversible enzymic inhibitors (eg sodium azide and cyanide) were added, the cathodic current induced by biofilm growth was inhibited.

  3. Cholesterol biosensor based on rf sputtered zinc oxide nanoporous thin film

    International Nuclear Information System (INIS)

    Singh, S. P.; Arya, Sunil K.; Pandey, Pratibha; Malhotra, B. D.; Saha, Shibu; Sreenivas, K.; Gupta, Vinay

    2007-01-01

    Cholesterol oxidase (ChOx) has been immobilized onto zinc oxide (ZnO) nanoporous thin films grown on gold surface. A preferred c-axis oriented ZnO thin film with porous surface morphology has been fabricated by rf sputtering under high pressure. Optical studies and cyclic voltammetric measurements show that the ChOx/ZnO/Au bioelectrode is sensitive to the detection of cholesterol in 25-400 mg/dl range. A relatively low value of enzyme's kinetic parameter (Michaelis-Menten constant) ∼2.1 mM indicates enhanced enzyme affinity of ChOx to cholesterol. The observed results show promising application of nanoporous ZnO thin film for biosensing application without any functionalization

  4. Characterization of lipase in reversed micelles formulated by Cibacron Blue F-3GA modified Span 85

    DEFF Research Database (Denmark)

    Zhang, Dong Hao; Guo, Zheng; Sun, Yan

    2007-01-01

    Sorbitan trioleate (Span 85) modified by Cibacron Blue F-3GA (CB) was prepared and used as an affinity surfactant to formulate a reversed micellar system for Candida rugosa lipase (CRL) solubilization. The system was characterized and evaluated by employing CRL-catalyzed hydrolysis of olive oil...... of the encapsulated lipase remained unchanged, but the apparent activity was significantly higher than that of the native enzyme in bulk solution. Kinetic studies indicated that the encapsulated lipase in the reversed micelles of CB-formulated Span 85 followed the Michaelis-Menten equation. The Michaelis constant...... was found to decrease with increasing surfactant concentration, suggesting an increase of the enzyme affinity for the substrate. Stability of the lipase in the reversed micelles was negatively correlated to W0. Introduction Reversed micelles are nanometer-scale transparent aggregates of water and surfactant...

  5. Nanoporous cerium oxide thin film for glucose biosensor.

    Science.gov (United States)

    Saha, Shibu; Arya, Sunil K; Singh, S P; Sreenivas, K; Malhotra, B D; Gupta, Vinay

    2009-03-15

    Nanoporous cerium oxide (CeO(2)) thin film deposited onto platinum (Pt) coated glass plate using pulsed laser deposition (PLD) has been utilized for immobilization of glucose oxidase (GOx). Atomic force microscopy studies reveal the formation of nanoporous surface morphology of CeO(2) thin film. Response studies carried out using differential pulsed voltammetry (DPV) and optical measurements show that the GOx/CeO(2)/Pt bio-electrode shows linearity in the range of 25-300 mg/dl of glucose concentration. The low value of Michaelis-Menten constant (1.01 mM) indicates enhanced enzyme affinity of GOx to glucose. The observed results show promising application of the nanoporous CeO(2) thin film for glucose sensing application without any surface functionalization or mediator.

  6. 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.

  7. The kinetics of denitrification in permeable sediments

    DEFF Research Database (Denmark)

    Evrard, Victor; Glud, Ronnie N.; Cook, Perran L. M.

    2013-01-01

    Permeable sediments comprise the majority of shelf sediments, yet the rates of denitrification remain highly uncertain in these environments. Computational models are increasingly being used to understand the dynamics of denitrification in permeable sediments, which are complex environments...... on sediments taken from six shallow coastal sites in Port Phillip Bay, Victoria, Australia. The results showed that denitrification commenced rapidly (within 30 min) after the onset of anoxia and the kinetics could be well described by Michaelis-Menten kinetics with half saturation constants (apparent K...... in cohesive sediments despite organic carbon contents one order of magnitude lower for the sediments studied here. The ratio of sediment O-2 consumption to V-max was in the range of 0.02-0.09, and was on average much lower than the theoretical ratio of 0.8. As a consequence, models implemented...

  8. Rainforest metropolis casts 1,000-km defaunation shadow.

    Science.gov (United States)

    Tregidgo, Daniel J; Barlow, Jos; Pompeu, Paulo S; de Almeida Rocha, Mayana; Parry, Luke

    2017-08-08

    Tropical rainforest regions are urbanizing rapidly, yet the role of emerging metropolises in driving wildlife overharvesting in forests and inland waters is unknown. We present evidence of a large defaunation shadow around a rainforest metropolis. Using interviews with 392 rural fishers, we show that fishing has severely depleted a large-bodied keystone fish species, tambaqui ( Colossoma macropomum ), with an impact extending over 1,000 km from the rainforest city of Manaus (population 2.1 million). There was strong evidence of defaunation within this area, including a 50% reduction in body size and catch rate (catch per unit effort). Our findings link these declines to city-based boats that provide rural fishers with reliable access to fish buyers and ice and likely impact rural fisher livelihoods and flooded forest biodiversity. This empirical evidence that urban markets can defaunate deep into rainforest wilderness has implications for other urbanizing socioecological systems.

  9. Calibration methods and tools for KM3NeT

    Directory of Open Access Journals (Sweden)

    Kulikovskiy Vladimir

    2016-01-01

    Full Text Available The KM3NeT detectors, ARCA and ORCA, composed of several thousands digital optical modules, are in the process of their realization in the Mediterranean Sea. Each optical module contains 31 3-inch photomultipliers. Readout of the optical modules and other detector components is synchronized at the level of sub-nanoseconds. The position of the module is measured by acoustic piezo detectors inside the module and external acoustic emitters installed on the bottom of the sea. The orientation of the module is obtained with an internal attitude and heading reference system chip. Detector calibration, i.e. timing, positioning and sea-water properties, is overviewed in this talk and discussed in detail in this conference. Results of the procedure applied to the first detector unit ready for installation in the deep sea will be shown.

  10. Ambient Seismic Imaging of Hydraulically Active Fractures at km Depths

    Science.gov (United States)

    Malin, P. E.; Sicking, C.

    2017-12-01

    Streaming Depth Images of ambient seismic signals using numerous, densely-distributed, receivers have revealed their connection to hydraulically active fractures at 0.5 to 5 km depths. Key for this type of imaging is very high-fold stacking over both multiple receives and periods of a few hours. Also important is suppression of waveforms from fixed, repeating sources such as pumps, generators, and traffic. A typical surface-based ambient SDI survey would use a 3D seismic receiver grid. It would have 1,000 to 4,000 uniformly distributed receivers at a density of 50/km2over the target. If acquired by borehole receivers buried 100 m deep, the density can be dropped by an order of magnitude. We show examples of the acquisition and signal processing scenarios used to produce the ambient images. (Sicking et al., SEG Interpretation, Nov 2017.) While the fracture-fluid source connection of SDI has been verified by drilling and various types of hydraulic tests, the precise nature of the signal's origin is not clear. At the current level of observation, the signals do not have identifiable phases, but can be focused using P wave velocities. Suggested sources are resonances of pressures fluctuations in the fractures, or small, continuous, slips on fractures surfaces. In either case, it appears that the driving mechanism is tectonic strain in an inherently unstable crust. Solid earth tides may enhance these strains. We illustrate the value of the ambient SDI method in its industrial application by showing case histories from energy industry and carbon-capture-sequestration projects. These include ambient images taken before, during, and after hydraulic treatments in un-conventional reservoirs. The results show not only locations of active fractures, but also their time responses to stimulation and production. Time-lapse ambient imaging can forecast and track events such as well interferences and production changes that can result from nearby treatments.

  11. Nonlinear pharmacokinetics of visnagin in rats after intravenous bolus administration.

    Science.gov (United States)

    Haug, Karin G; Weber, Benjamin; Hochhaus, Guenther; Butterweck, Veronika

    2012-01-23

    Ammi visnaga L. (syn. Khella, Apiaceae) preparations have traditionally been used in the Middle East for the treatment of kidney stone disease. Visnagin, a furanocoumarin derivative, is one of the main compounds of Ammi visnaga with potential effects on kidney stone prevention. To date, no information is available about the pharmacokinetic (PK) properties of visnagin. It was the aim of the study to characterize the PK properties of visnagin after intravenous (i.v.) bolus administration in rats and to develop an adequate model for the description of the observed data, including model parameter estimates. Therefore, three doses of visnagin (1.25, 2.5, and 5mg/kg) solubilized in 25% Captisol® were administered by i.v. bolus injection to male Sprague-Dawley rats. Plasma samples were extracted and subsequently analyzed using a validated LC-MS/MS method. Both non-compartmental and compartmental PK analyses were performed. A stepwise model building approach was applied including nonlinear mixed effect modeling for final model selection and to obtain final model estimates in NONMEM VI. The average areas under the curve (AUC(0-last)) after doses of 1.25, 2.5, and 5mg/kg were 1.03, 3.61, and 12.6 mg *h/l, respectively. The shape of the plasma concentration-time profiles and the observed disproportionate increase in AUC(0-last) with increasing dose suggested nonlinearity in the elimination of visnagin. A two-compartment Michaelis-Menten model provided the best fit with following typical values of the parameter estimates: 2.09 mg/(l*h) (V(max)), 0.08 mg/l (K(M)), 0.175 l (V(C)), 1.0 h⁻¹ (k₁₂), and 1.22 h⁻¹ (k₂₁). Associated inter-subject variability estimates (% CV) for V(max), K(M) and V(C) were 21.8, 70.9, and 9.2, respectively. Intra-subject variability (constant CV error model) was estimated to be 7.0%. The results suggest the involvement of a saturable process in the elimination of visnagin, possibly an enzyme or transporter system. Copyright © 2011

  12. Bioprospecting arsenite oxidizing bacteria in the soil of the Comarca Lagunera

    Directory of Open Access Journals (Sweden)

    Edelweiss A. Rangel-Montoya

    2015-01-01

    Full Text Available Resumen El arsénico es uno de los metaloides más tóxicos presente en el ambiente y la exposición prolongada a este metal causa efectos crónicos en la salud. Por ello, la búsqueda de alternativas amigables con el medio ambiente, para el tratamiento de agua y suelos contaminados con arsénico es importante. En este trabajo se aislaron cepas bacterianas de suelos con presencia de arsénico en la Comarca Lagunera, para analizar aquellas con capacidad oxidante de arsenito. Las cepas 04-SP1qa y 14-SP1qh de metabolismo quimiolitoautotrófico y quimioheterotrófico, respectivamente, tuvieron mayor actividad de la enzima arsenito oxidasa. Las condiciones óptimas de crecimiento y la actividad enzimática de dichas cepas se investigaron. La cepa 04-SP1qa presentó actividad enzimática específica de 0.162 μmol·min- 1 ·mg-1, constante de Michaelis-Menten (Km de 3.37 μM y velocidad máxima (Vmax de 5.20 μM·min-1·mg-1 en condiciones óptimas de pH 8.0 y 40 °C. La cepa 14-SP1qh presentó actividad enzimática específica de 0.16 μmol·min-1·mg-1, Km de 3.70 μM y Vmax de 14.39 μM·min-1·mg-1 a pH 7.0 y 40 °C. Los resultados demostraron la presencia de bacterias oxidantes de arsenito con actividad enzimática en suelos de la Comarca Lagunera, identificando potencial para desarrollar nuevas tecnologías de biorremediación de aguas y suelos contaminados con arsénico en la región.

  13. Effects of a 4-week high-intensity interval training on pacing during 5-km running trial

    Directory of Open Access Journals (Sweden)

    R. Silva

    2017-10-01

    Full Text Available This study analyzed the influence of a 4-week high-intensity interval training on the pacing strategy adopted by runners during a 5-km running trial. Sixteen male recreational long-distance runners were randomly assigned to a control group (CON, n=8 or a high-intensity interval training group (HIIT, n=8. The HIIT group performed high-intensity interval-training twice per week, while the CON group maintained their regular training program. Before and after the training period, the runners performed an incremental exercise test to exhaustion to measure the onset of blood lactate accumulation, maximal oxygen uptake (VO2max, and peak treadmill speed (PTS. A submaximal constant-speed test to measure the running economy (RE and a 5-km running trial on an outdoor track to establish pacing strategy and performance were also done. During the 5-km running trial, the rating of perceived exertion (RPE and time to cover the 5-km trial (T5 were registered. After the training period, there were significant improvements in the HIIT group of ∼7 and 5% for RE (P=0.012 and PTS (P=0.019, respectively. There was no significant difference between the groups for VO2max (P=0.495 or onset of blood lactate accumulation (P=0.101. No difference was found in the parameters measured during the 5-km trial before the training period between HIIT and CON (P>0.05. These findings suggest that 4 weeks of HIIT can improve some traditional physiological variables related to endurance performance (RE and PTS, but it does not alter the perception of effort, pacing strategy, or overall performance during a 5-km running trial.

  14. Ultra-high velocity impacts: Cratering studies of microscopic impacts from 3 km/s to 30 km/s

    International Nuclear Information System (INIS)

    Stradling, G.L.; Idzorek, G.C.; Shafer, B.P.; Curling, H.L. Jr.; Collopy, M.T.; Hopkins Blossom, A.A.; Fuerstenau, S.

    1992-01-01

    Cratering experiments performed under carefully controlled conditions at impact velocities ranging from 3 km/s to 30 km/s into a wide variety of target materials are presented. These impact experiments use the 6 MV vertical Van de Graaff accelerator of the Ion Beam Facility at the Los Alamos National Laboratory to electrostatically accelerate highly charged iron microspheres. The sub-micron spheres, from a random size distribution, are shocklessly accelerated along an 8 m flight path. Ultra-sensitive charge detectors monitor the passage of the projectiles at a rate of up to 100 projectiles/second. An online computer records and displays in real time the charge, velocity and mass of the projectiles and provides cross correlation between the events observed by the several in-flight charge detectors and impact detectors. Real-time logic controls an electrostatic kicker which deflects projectiles of selected charge and velocity onto the target. Thus each experiment consists of an ensemble of 10 to 40 impacts onto a single target within a narrow window of the projectile parameter space, providing excellent statistical resolution of each data point. The target materials used include single crystal copper and single crystal aluminum, gold, and quartz as well as pyrolytic graphic and epoxy used in composite materials of interest to space applications. We also conducted impact experiments onto thin Mylar and nickel foils. This paper presents these experiments and summarizes the cratering characterization performed to date. Emphasis is placed on cratering results in several materials over a range of impact velocities

  15. Evaluation of the 7-km GEOS-5 Nature Run

    Science.gov (United States)

    Gelaro, Ronald; Putman, William M.; Pawson, Steven; Draper, Clara; Molod, Andrea; Norris, Peter M.; Ott, Lesley; Prive, Nikki; Reale, Oreste; Achuthavarier, Deepthi; hide

    2015-01-01

    This report documents an evaluation by the Global Modeling and Assimilation Office (GMAO) of a two-year 7-km-resolution non-hydrostatic global mesoscale simulation produced with the Goddard Earth Observing System (GEOS-5) atmospheric general circulation model. The simulation was produced as a Nature Run for conducting observing system simulation experiments (OSSEs). Generation of the GEOS-5 Nature Run (G5NR) was motivated in part by the desire of the OSSE community for an improved high-resolution sequel to an existing Nature Run produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), which has served the community for several years. The intended use of the G5NR in this context is for generating simulated observations to test proposed observing system designs regarding new instruments and their deployments. Because NASA's interest in OSSEs extends beyond traditional weather forecasting applications, the G5NR includes, in addition to standard meteorological components, a suite of aerosol types and several trace gas concentrations, with emissions downscaled to 10 km using ancillary information such as power plant location, population density and night-light information. The evaluation exercise described here involved more than twenty-five GMAO scientists investigating various aspects of the G5NR performance, including time mean temperature and wind fields, energy spectra, precipitation and the hydrological cycle, the representation of waves, tropical cyclones and midlatitude storms, land and ocean surface characteristics, the representation and forcing effects of clouds and radiation, dynamics of the stratosphere and mesosphere, and the representation of aerosols and trace gases. Comparisons are made with observational data sets when possible, as well as with reanalyses and other long model simulations. The evaluation is broad in scope, as it is meant to assess the overall realism of basic aspects of the G5NR deemed relevant to the conduct of OSSEs

  16. 1km Global Terrestrial Carbon Flux: Estimations and Evaluations

    Science.gov (United States)

    Murakami, K.; Sasai, T.; Kato, S.; Saito, M.; Matsunaga, T.; Hiraki, K.; Maksyutov, S. S.

    2017-12-01

    Estimating global scale of the terrestrial carbon flux change with high accuracy and high resolution is important to understand global environmental changes. Furthermore the estimations of the global spatiotemporal distribution may contribute to the political and social activities such as REDD+. In order to reveal the current state of terrestrial carbon fluxes covering all over the world and a decadal scale. The satellite-based diagnostic biosphere model is suitable for achieving this purpose owing to observing on the present global land surface condition uniformly at some time interval. In this study, we estimated the global terrestrial carbon fluxes with 1km grids by using the terrestrial biosphere model (BEAMS). And we evaluated our new carbon flux estimations on various spatial scales and showed the transition of forest carbon stocks in some regions. Because BEAMS required high resolution meteorological data and satellite data as input data, we made 1km interpolated data using a kriging method. The data used in this study were JRA-55, GPCP, GOSAT L4B atmospheric CO2 data as meteorological data, and MODIS land product as land surface satellite data. Interpolating process was performed on the meteorological data because of insufficient resolution, but not on MODIS data. We evaluated our new carbon flux estimations using the flux tower measurement (FLUXNET2015 Datasets) in a point scale. We used 166 sites data for evaluating our model results. These flux sites are classified following vegetation type (DBF, EBF, ENF, mixed forests, grass lands, croplands, shrub lands, Savannas, wetlands). In global scale, the BEAMS estimations was underestimated compared to the flux measurements in the case of carbon uptake and release. The monthly variations of NEP showed relatively high correlations in DBF and mixed forests, but the correlation coefficients of EBF, ENF, and grass lands were less than 0.5. In the meteorological factors, air temperature and solar radiation showed

  17. ASIC design in the KM3NeT detector

    International Nuclear Information System (INIS)

    Gajanana, D; Gromov, V; Timmer, P

    2013-01-01

    In the KM3NeT project [1], Cherenkov light from the muon interactions with transparent matter around the detector, is used to detect neutrinos. Photo multiplier tubes (PMT) used as photon sensor, are housed in a glass sphere (aka Optical Module) to detect single photons from the Cherenkov light. The PMT needs high operational voltage ( ∼ 1.5 kV) and is generated by a Cockroft-Walton (CW) multiplier circuit. The electronics required to control the PMT's and collect the signals is integrated in two ASIC's namely: 1) a front-end mixed signal ASIC (PROMiS) for the readout of the PMT and 2) an analog ASIC (CoCo) to generate pulses for charging the CW circuit and to control the feedback of the CW circuit. In this article, we discuss the two integrated circuits and test results of the complete setup. PROMiS amplifies the input charge, converts it to a pulse width and delivers the information via LVDS signals. These LVDS signals carry accurate information on the Time of arrival ( 2 C bus. This unique combination of the ASIC's results in a very cost and power efficient PMT base design.

  18. Stratospheric microbiology at 20 km over the Pacific Ocean

    Science.gov (United States)

    Smith, David J.; Griffin, Dale W.; Schuerger, Andrew C.

    2010-01-01

    An aerobiology sampling flight at 20 km was conducted on 28 April 2008 over the Pacific Ocean (36.5° N, 118–149° W), a period of time that coincided with the movement of Asian dust across the ocean. The aim of this study was to confirm the presence of viable bacteria and fungi within a transoceanic, atmospheric bridge and to improve the resolution of flight hardware processing techniques. Isolates of the microbial strains recovered were analyzed with ribosomal ribonucleic acid (rRNA) sequencing to identify bacterial species Bacillus sp., Bacillus subtilis, Bacillus endophyticus, and the fungal genus Penicillium. Satellite imagery and ground-based radiosonde observations were used to measure dust movement and characterize the high-altitude environment at the time of collection. Considering the atmospheric residency time (7–10 days), the extreme temperature regime of the environment (-75°C), and the absence of a mechanism that could sustain particulates at high altitude, it is unlikely that our samples indicate a permanent, stratospheric ecosystem. However, the presence of viable fungi and bacteria in transoceanic stratosphere remains relevant to understanding the distribution and extent of microbial life on Earth.

  19. Production of Biodiesel from Waste Vegetable Oil via KM Micromixer

    Directory of Open Access Journals (Sweden)

    M. F. Elkady

    2015-01-01

    Full Text Available The production of biodiesel from waste vegetable oils through its pretreatment followed by transesterification process in presence of methanol was investigated using a KM micromixer reactor. The parameters affecting biodiesel production process such as alcohol to oil molar ratio, catalyst concentration, the presence of tetrahydrofuran (THF as a cosolvent, and the volumetric flow rates of inlet fluids were optimized. The properties of the produced biodiesel were compared with its parent waste oil through different characterization techniques. The presence of methyl ester groups at the produced biodiesel was confirmed using both the gas chromatography-mass spectrometry (GC-MS and the infrared spectroscopy (FT-IR. Moreover, the thermal analysis of the produced biodiesel and the comparable waste oil indicated that the product after the transesterification process began to vaporize at 120°C which makes it lighter than its parent oil which started to vaporize at around 300°C. The maximum biodiesel production yield of 97% was recorded using 12 : 1 methanol to oil molar ratio in presence of both 1% NaOH and THF/methanol volume ratio 0.3 at 60 mL/h flow rate.

  20. CODATA recommended values of the fundamental constants

    International Nuclear Information System (INIS)

    Mohr, Peter J.; Taylor, Barry N.

    2000-01-01

    A review is given of the latest Committee on Data for Science and Technology (CODATA) adjustment of the values of the fundamental constants. The new set of constants, referred to as the 1998 values, replaces the values recommended for international use by CODATA in 1986. The values of the constants, and particularly the Rydberg constant, are of relevance to the calculation of precise atomic spectra. The standard uncertainty (estimated standard deviation) of the new recommended value of the Rydberg constant, which is based on precision frequency metrology and a detailed analysis of the theory, is approximately 1/160 times the uncertainty of the 1986 value. The new set of recommended values as well as a searchable bibliographic database that gives citations to the relevant literature is available on the World Wide Web at physics.nist.gov/constants and physics.nist.gov/constantsbib, respectively

  1. Stability constants of scandium complexes, 1

    International Nuclear Information System (INIS)

    Itoh, Hisako; Itoh, Naomi; Suzuki, Yasuo

    1984-01-01

    The stability constants of scandium complexes with some carboxylate ligands were determined potentiometrically at 25.0 and 40.0 0 C and at an ionic strength of 0.10 with potassium nitrate as supporting electrolyte. The constants of the scandium complexes were appreciably greater than those of the corresponding lanthanoid complexes, as expected. The changes in free energy, enthalpy, and entropy for the formation of the scandium complexes were calculated from the stability constants at two temperatures. (author)

  2. Constant exposure technique in industrial radiography

    International Nuclear Information System (INIS)

    Domanus, J.C.

    1983-08-01

    The principles and advantages of the constant exposure technique are explained. Choice of exposure factors is analyzed. Film, paper and intensifying screens used throughout the investigation and film and paper processing are described. Exposure technique and the use of image quality indicators are given. Methods of determining of radiographic image quality are presented. Conclusions about the use of constant exposure vs. constant kilovoltage technique are formulated. (author)

  3. Dose rate constants for new dose quantities

    International Nuclear Information System (INIS)

    Tschurlovits, M.; Daverda, G.; Leitner, A.

    1992-01-01

    Conceptual changes and new quantities made is necessary to reassess dose rate quantities. Calculations of the dose rate constant were done for air kerma, ambient dose equivalent and directional dose equivalent. The number of radionuclides is more than 200. The threshold energy is selected as 20 keV for the dose equivalent constants. The dose rate constant for the photon equivalent dose as used mainly in German speaking countries as a temporary quantity is also included. (Author)

  4. A natural cosmological constant from chameleons

    International Nuclear Information System (INIS)

    Nastase, Horatiu; Weltman, Amanda

    2015-01-01

    We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero) and the coincidence problem (why Λ is comparable to the matter density now)

  5. A natural cosmological constant from chameleons

    Directory of Open Access Journals (Sweden)

    Horatiu Nastase

    2015-07-01

    Full Text Available We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero and the coincidence problem (why Λ is comparable to the matter density now.

  6. A natural cosmological constant from chameleons

    Energy Technology Data Exchange (ETDEWEB)

    Nastase, Horatiu, E-mail: nastase@ift.unesp.br [Instituto de Física Teórica, UNESP-Universidade Estadual Paulista, R. Dr. Bento T. Ferraz 271, Bl. II, Sao Paulo 01140-070, SP (Brazil); Weltman, Amanda, E-mail: amanda.weltman@uct.ac.za [Astrophysics, Cosmology & Gravity Center, Department of Mathematics and Applied Mathematics, University of Cape Town, Private Bag, Rondebosch 7700 (South Africa)

    2015-07-30

    We present a simple model where the effective cosmological constant appears from chameleon scalar fields. For a Kachru–Kallosh–Linde–Trivedi (KKLT)-inspired form of the potential and a particular chameleon coupling to the local density, patches of approximately constant scalar field potential cluster around regions of matter with density above a certain value, generating the effect of a cosmological constant on large scales. This construction addresses both the cosmological constant problem (why Λ is so small, yet nonzero) and the coincidence problem (why Λ is comparable to the matter density now)

  7. File Specification for the 7-km GEOS-5 Nature Run, Ganymed Release Non-Hydrostatic 7-km Global Mesoscale Simulation

    Science.gov (United States)

    da Silva, Arlindo M.; Putman, William; Nattala, J.

    2014-01-01

    This document describes the gridded output files produced by a two-year global, non-hydrostatic mesoscale simulation for the period 2005-2006 produced with the non-hydrostatic version of GEOS-5 Atmospheric Global Climate Model (AGCM). In addition to standard meteorological parameters (wind, temperature, moisture, surface pressure), this simulation includes 15 aerosol tracers (dust, sea-salt, sulfate, black and organic carbon), O3, CO and CO2. This model simulation is driven by prescribed sea-surface temperature and sea-ice, daily volcanic and biomass burning emissions, as well as high-resolution inventories of anthropogenic sources. A description of the GEOS-5 model configuration used for this simulation can be found in Putman et al. (2014). The simulation is performed at a horizontal resolution of 7 km using a cubed-sphere horizontal grid with 72 vertical levels, extending up to to 0.01 hPa (approximately 80 km). For user convenience, all data products are generated on two logically rectangular longitude-latitude grids: a full-resolution 0.0625 deg grid that approximately matches the native cubed-sphere resolution, and another 0.5 deg reduced-resolution grid. The majority of the full-resolution data products are instantaneous with some fields being time-averaged. The reduced-resolution datasets are mostly time-averaged, with some fields being instantaneous. Hourly data intervals are used for the reduced-resolution datasets, while 30-minute intervals are used for the full-resolution products. All full-resolution output is on the model's native 72-layer hybrid sigma-pressure vertical grid, while the reduced-resolution output is given on native vertical levels and on 48 pressure surfaces extending up to 0.02 hPa. Section 4 presents additional details on horizontal and vertical grids. Information of the model surface representation can be found in Appendix B. The GEOS-5 product is organized into file collections that are described in detail in Appendix C. Additional

  8. A high resolution (1 km) groundwater model for Indonesia

    Science.gov (United States)

    Sutanudjaja, Edwin; Verkaik, Jarno; de Graaf, Inge; van Beek, Rens; Erkens, Gilles; Bierkens, Marc

    2015-04-01

    Groundwater is important in many parts of Indonesia. It serves as a primary source of drinking water and industrial activities. During times of drought, it sustains water flows in streams, rivers, lakes and wetlands, and thus support ecosystem habitat and biodiversity as well as preventing hazardous forest fire. Besides its importance, groundwater is known as a vulnerable resource as unsustainable groundwater exploitation and management occurs in many areas of the country. Therefore, in order to ensure sustainable management of groundwater resources, monitoring and predicting groundwater changes in Indonesia are imperative. However, large extent groundwater models to assess these changes on a regional scale are almost non-existent and are hampered by the strong topographical and lithological transitions that characterize Indonesia. In this study, we built an 1 km resolution groundwater model for the entire Indonesian archipelago (total inland area: about 2 million km2). We adopted the approaches of Sutanudjaja et al. (2011, 2014a) and de Graaf et al. (2014) in order to make a MODFLOW (Harbaugh et al., 2000) groundwater model by using only global datasets. Aquifer schematization and properties of the groundwater model were developed from available global lithological maps (e.g. Dürr et al., 2005; Gleeson et al., 2011; Hartmann & Moorsdorf, 2012; Gleeson et al., 2014). We forced the groundwater model with the recent output of global hydrological model PCR-GLOBWB version 2.0 (Sutanudjaja et al., 2014b; van Beek et al., 2011), specifically the long term average of groundwater recharge and average surface water levels derived from channel discharge. Simulation results were promising. The MODFLOW model converged with realistic aquifer properties (i.e. transmissivities) and produced reasonable groundwater head spatial distribution reflecting the positions of major groundwater bodies and surface water bodies in the country. In Vienna, we aim to show and demonstrate these

  9. Inference of viscosity jump at 670 km depth and lower mantle viscosity structure from GIA observations

    Science.gov (United States)

    Nakada, Masao; Okuno, Jun'ichi; Irie, Yoshiya

    2018-03-01

    A viscosity model with an exponential profile described by temperature (T) and pressure (P) distributions and constant activation energy (E_{{{um}}}^{{*}} for the upper mantle and E_{{{lm}}}^* for the lower mantle) and volume (V_{{{um}}}^{{*}} and V_{{{lm}}}^*) is employed in inferring the viscosity structure of the Earth's mantle from observations of glacial isostatic adjustment (GIA). We first construct standard viscosity models with an average upper-mantle viscosity ({\\bar{η }_{{{um}}}}) of 2 × 1020 Pa s, a typical value for the oceanic upper-mantle viscosity, satisfying the observationally derived three GIA-related observables, GIA-induced rate of change of the degree-two zonal harmonic of the geopotential, {\\dot{J}_2}, and differential relative sea level (RSL) changes for the Last Glacial Maximum sea levels at Barbados and Bonaparte Gulf in Australia and for RSL changes at 6 kyr BP for Karumba and Halifax Bay in Australia. Standard viscosity models inferred from three GIA-related observables are characterized by a viscosity of ˜1023 Pa s in the deep mantle for an assumed viscosity at 670 km depth, ηlm(670), of (1 - 50) × 1021 Pa s. Postglacial RSL changes at Southport, Bermuda and Everglades in the intermediate region of the North American ice sheet, largely dependent on its gross melting history, have a crucial potential for inference of a viscosity jump at 670 km depth. The analyses of these RSL changes based on the viscosity models with {\\bar{η }_{{{um}}}} ≥ 2 × 1020 Pa s and lower-mantle viscosity structures for the standard models yield permissible {\\bar{η }_{{{um}}}} and ηlm (670) values, although there is a trade-off between the viscosity and ice history models. Our preferred {\\bar{η }_{{{um}}}} and ηlm (670) values are ˜(7 - 9) × 1020 and ˜1022 Pa s, respectively, and the {\\bar{η }_{{{um}}}} is higher than that for the typical value of oceanic upper mantle, which may reflect a moderate laterally heterogeneous upper

  10. KINETIKA FERMENTASI SELULOSA MURNI OLEH Trichoderma reesi QM 9414 MENJADI GLUKOSA DAN PENERAPANNYA PADA JERAMI PADI BEBAS LIGNIN [Kinetics of Pure Cellulose Fermentation by Trichoderma Reesei QM 9414 to Glucose and Its Application of on Lignin Free Rice Straw

    Directory of Open Access Journals (Sweden)

    M Iyan Sofyan

    2004-12-01

    Full Text Available The objectives of this research were: 1 to determine aeration rate and substrate concentration of pure cellulose to produce maximum glucose by Trichoderma reesei QM 9414 at 30 oC, and agitation 150 rpm; 2 to study the kinetics of pure cellulose fermentation by Trichoderma reesei QM 9414 to glucose and its implication upon fermentation of the lignin free rice straw. The experiment was arranged in factorial randomized complete design in three times replication. Treatments consisted of three levels of aeration (1,00 vvm; 1,5 vvm; 2,0 vvm and three levels of substrate concentration (0,75 ; 1,00 ; 1,25 % w/v. The results showed that at the exponential phase the average specific growth of Trichoderma reesei QM 9414 was 0,05374 hour-1, the maximum glucose product concentration of pure cellulose was 0.1644 gL-1,and the oxygen transfer was 0,0328 mg L-1 hour-1. According to t-test, the kinetics of pure cellulose fermentation model just the same as the lignin free rice straw fermentation.The enzymes produced by Trichoderma reesei QM 9414 in pure cellulose fermentation media followed the Michaelis-Menten model. The enzyme kinetic parameters were the maximum growth rate was 37x10-3 hour-1 and Michaelis-Menten constant was ½ maximum μ =17,5x10-3 hour-1. The volumetric oxygen transfer (KLa using rice straw was 0,0337 mg.hour-1. The value of KLa could be used for conversion from bioreactor at laboratory scale to commercial scale design.

  11. 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

  12. Equilibrium-constant expressions for aqueous plutonium

    International Nuclear Information System (INIS)

    Silver, G.L.

    2010-01-01

    Equilibrium-constant expressions for Pu disproportionation reactions traditionally contain three or four terms representing the concentrations or fractions of the oxidation states. The expressions can be rewritten so that one of the oxidation states is replaced by a term containing the oxidation number of the plutonium. Experimental estimations of the numerical values of the constants can then be checked in several ways. (author)

  13. A null test of the cosmological constant

    International Nuclear Information System (INIS)

    Chiba, Takeshi; Nakamura, Takashi

    2007-01-01

    We provide a consistency relation between cosmological observables in general relativity with the cosmological constant. Breaking of this relation at any redshift would imply the breakdown of the hypothesis of the cosmological constant as an explanation of the current acceleration of the universe. (author)

  14. A stringy nature needs just two constants

    International Nuclear Information System (INIS)

    Veneziano, G.

    1986-01-01

    Dual string theories of everything, being purely geometrical, contain only two fundamental constants: c, for relativistic invariance, and a length lambda, for quantization. Planck's and Newton's constants appear only through Planck's length, a ''calculable'' fraction of lambda. Only the existence of a light sector breaks a ''reciprocity'' principle and unification at lambda, which is also the theory's cut-off

  15. On special relativity with cosmological constant

    International Nuclear Information System (INIS)

    Guo Hanying; Huang Chaoguang; Xu Zhan; Zhou Bin

    2004-01-01

    Based on the principle of relativity and the postulate of invariant speed and length, we propose the theory of special relativity with cosmological constant SRc,R, in which the cosmological constant is linked with the invariant length. Its relation with the doubly special relativity is briefly mentioned

  16. DETERMINATION OF STABILITY CONSTANTS OF MANGANESE (II ...

    African Journals Online (AJOL)

    DR. AMINU

    Keywords: Amino acids, dissociation constant, potentiometry, stability constant. INTRODUCTION. Acids – base titration involves the gradual addition or removal of protons for example using the deprotic form of glycine. The plot has two distinct stages corresponding to the deprotonation of the two different groups on glycine.

  17. Shapley Value for Constant-sum Games

    NARCIS (Netherlands)

    Khmelnitskaya, A.B.

    2002-01-01

    It is proved that Young's axiomatization for the Shapley value by marginalism, efficiency, and symmetry is still valid for the Shapley value defined on the class of nonnegative constant-sum games and on the entire class of constant-sum games as well. To support an interest to study the class of

  18. Constant Width Planar Computation Characterizes ACC0

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Arnsfelt

    2006-01-01

    We obtain a characterization of ACC0 in terms of a natural class of constant width circuits, namely in terms of constant width polynomial size planar circuits. This is shown via a characterization of the class of acyclic digraphs which can be embedded on a cylinder surface in such a way that all...

  19. Experimental Determination of the Avogadro Constant

    Indian Academy of Sciences (India)

    mental physical constant such as charge of an electron or the. Boltzmann constant ... ideas was that the number of particles or molecules in a gas of given volume could not ... knowledge of at least one property of a single molecule. Loschmidt ...

  20. The time constant of the somatogravic illusion.

    Science.gov (United States)

    Correia Grácio, B J; de Winkel, K N; Groen, E L; Wentink, M; Bos, J E

    2013-02-01

    Without visual feedback, humans perceive tilt when experiencing a sustained linear acceleration. This tilt illusion is commonly referred to as the somatogravic illusion. Although the physiological basis of the illusion seems to be well understood, the dynamic behavior is still subject to discussion. In this study, the dynamic behavior of the illusion was measured experimentally for three motion profiles with different frequency content. Subjects were exposed to pure centripetal accelerations in the lateral direction and were asked to indicate their tilt percept by means of a joystick. Variable-radius centrifugation during constant angular rotation was used to generate these motion profiles. Two self-motion perception models were fitted to the experimental data and were used to obtain the time constant of the somatogravic illusion. Results showed that the time constant of the somatogravic illusion was on the order of two seconds, in contrast to the higher time constant found in fixed-radius centrifugation studies. Furthermore, the time constant was significantly affected by the frequency content of the motion profiles. Motion profiles with higher frequency content revealed shorter time constants which cannot be explained by self-motion perception models that assume a fixed time constant. Therefore, these models need to be improved with a mechanism that deals with this variable time constant. Apart from the fundamental importance, these results also have practical consequences for the simulation of sustained accelerations in motion simulators.

  1. Zero cosmological constant from normalized general relativity

    International Nuclear Information System (INIS)

    Davidson, Aharon; Rubin, Shimon

    2009-01-01

    Normalizing the Einstein-Hilbert action by the volume functional makes the theory invariant under constant shifts in the Lagrangian. The associated field equations then resemble unimodular gravity whose otherwise arbitrary cosmological constant is now determined as a Machian universal average. We prove that an empty space-time is necessarily Ricci tensor flat, and demonstrate the vanishing of the cosmological constant within the scalar field paradigm. The cosmological analysis, carried out at the mini-superspace level, reveals a vanishing cosmological constant for a universe which cannot be closed as long as gravity is attractive. Finally, we give an example of a normalized theory of gravity which does give rise to a non-zero cosmological constant.

  2. Graviton fluctuations erase the cosmological constant

    Science.gov (United States)

    Wetterich, C.

    2017-10-01

    Graviton fluctuations induce strong non-perturbative infrared renormalization effects for the cosmological constant. The functional renormalization flow drives a positive cosmological constant towards zero, solving the cosmological constant problem without the need to tune parameters. We propose a simple computation of the graviton contribution to the flow of the effective potential for scalar fields. Within variable gravity, with effective Planck mass proportional to the scalar field, we find that the potential increases asymptotically at most quadratically with the scalar field. The solutions of the derived cosmological equations lead to an asymptotically vanishing cosmological "constant" in the infinite future, providing for dynamical dark energy in the present cosmological epoch. Beyond a solution of the cosmological constant problem, our simplified computation also entails a sizeable positive graviton-induced anomalous dimension for the quartic Higgs coupling in the ultraviolet regime, substantiating the successful prediction of the Higgs boson mass within the asymptotic safety scenario for quantum gravity.

  3. Solar constant values for estimating solar radiation

    International Nuclear Information System (INIS)

    Li, Huashan; Lian, Yongwang; Wang, Xianlong; Ma, Weibin; Zhao, Liang

    2011-01-01

    There are many solar constant values given and adopted by researchers, leading to confusion in estimating solar radiation. In this study, some solar constant values collected from literature for estimating solar radiation with the Angstroem-Prescott correlation are tested in China using the measured data between 1971 and 2000. According to the ranking method based on the t-statistic, a strategy to select the best solar constant value for estimating the monthly average daily global solar radiation with the Angstroem-Prescott correlation is proposed. -- Research highlights: → The effect of the solar constant on estimating solar radiation is investigated. → The investigation covers a diverse range of climate and geography in China. → A strategy to select the best solar constant for estimating radiation is proposed.

  4. Receptor protein of Lysinibacillus sphaericus mosquito-larvicidal toxin displays amylomaltase activity.

    Science.gov (United States)

    Sharma, Mahima; Gupta, Gagan D; Kumar, Vinay

    2018-02-01

    The activated binary toxin (BinAB) from Lysinibacillus sphaericus binds to surface receptor protein (Cqm1) on the midgut cell membrane and kills Culex quinquefasciatus larvae on internalization. Cqm1 is attached to cells via a glycosyl-phosphatidylinositol (GPI) anchor. It has been classified as a member of glycoside hydrolase family 13 of the CAZy database. Here, we report characterization of the ordered domain (residues 23-560) of Cqm1. Gene expressing Cqm1 of BinAB susceptible mosquito was chemically synthesized and the protein was purified using E. coli expression system. Values for the Michaelis-Menten kinetics parameters towards 4-nitrophenyl α-D-glucopyranoside (α-pNPG) substrate were estimated to be 0.44 mM (Km) and 1.9 s -1 (kcat). Thin layer chromatography experiments established Cqm1 as α-glucosidase competent to cleave α-1,4-glycosidic bonds of maltose and maltotriose with high glycosyltransferase activity to form glucose-oligomers. The observed hydrolysis and synthesis of glucose-oligomers is consistent with open and accessible active-site in the structural model. The protein also hydrolyses glycogen and sucrose. These activities suggest that Cqm1 may be involved in carbohydrate metabolism in mosquitoes. Further, toxic BinA component does not inhibit α-glucosidase activity of Cqm1, while BinB reduced the activity by nearly 50%. The surface plasmon resonance study reveals strong binding of BinB with Cqm1 (Kd, 9.8 nM). BinA interaction with Cqm1 however, is 1000-fold weaker. Notably the estimated Kd values match well with dissociation constants reported earlier with larvae brush border membrane fractions. The Cqm1 protein forms a stable dimer that is consistent with its apical localization in lipid rafts. Its melting temperature (T m ) as observed by thermofluor-shift assay is 51.5 °C and Ca 2+ provides structural stability to the protein. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Constraints on the gravitational constant from observations of white dwarfs

    International Nuclear Information System (INIS)

    Blinnikov, S.I.

    1978-01-01

    Recently some authors have questioned whether Newton's law of gravitation is actually true on scales less than 1 km. The available constraints on the gravitational constant show that its laboratory value G 0 may differ from the value at infinity Gsub(infinity) by approximately 40%. Long (1976) reported experimental evidence for departures from Newton's law. In this note it is shown that the difference between G 0 and Gsub(infinity) modifies the mass-radius relation of degenerate stars. The observations of white dwarfs are consistent with the theory of stellar evolution only if G 0 differs from Gsub(infinity) by not more than approximately 10%. This estimate may be improved by a higher accuracy of observations. (Auth.)

  6. The Effect of Creatin and Carnitine Supplementation on 5 kmClassic and 10 km Free Styles Race Performance of Cross Country Skiers

    OpenAIRE

    Ebru ÇETİN

    2004-01-01

    This İnvestigation examined the effect of creatin and carnitine supplementation on 5 km classic and 10 km free styles race performance of competitive cross country skiers.Eighteen highly trained (12 male and 6 female) cross country skiers aged 13-16 years seperated into 3 equal groups. All groups participated in the 5 km classic and 10 km free races styles in Erciyes at 2200m altitude ski center before the carnitine and creatine loading. After the race subjects were seperated into carnitine, ...

  7. Nighttime ionization by energetic particles at Wallops Island in the altitude region 120 to 200 km

    International Nuclear Information System (INIS)

    Voss, H.D.; Smith, L.G.

    1979-01-01

    Five Nike Apache rockets, each including an energetic particle spectrometer and an electron density-electron temperature experiment, have been launched from Wallops Island (L=2.6) near midnight under varying geomagnetic conditions. On the most recent of these (5 January 1978) an additional spectrometer with a broom magnet, and a 391.4 nm photometer were flown. The data from this flight indicate that the energetic particle flux consists predominantly of protons, neutral hydrogen and possibly other energetic nuclei. The energy spectrum becomes much softer and the flux more intense with increasing Kp for 10 0 indicating that the majority of particles are near their mirroring altitude. Ionization rates are calculated based on the measured energy spectrum and mirror height distribution. The resulting ionization rate profile is found to be nearly constant with altitude in the region 120 to 200 km. The measured energetic particle flux and calculated ionization rate from the five flights are found to vary with magnetic activity (based on the Kp and Dst indexes) in the same way as the independently derived ionization rates deduced from the electron density profile

  8. Statistical orientation fluctuations: constant angular momentum versus constant rotational frequency constraints

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, A L [Tulane Univ., New Orleans, LA (United States)

    1992-08-01

    Statistical orientation fluctuations are calculated with two alternative assumptions: the rotational frequency remains constant as the shape orientation fluctuates; and, the average angular momentum remains constant as the shape orientation fluctuates. (author). 2 refs., 3 figs.

  9. On the constants for some Sobolev imbeddings

    Directory of Open Access Journals (Sweden)

    Pizzocchero Livio

    2001-01-01

    Full Text Available We consider the imbedding inequality is the Sobolev space (or Bessel potential space of type and (integer or fractional order . We write down upper bounds for the constants , using an argument previously applied in the literature in particular cases. We prove that the upper bounds computed in this way are in fact the sharp constants if , , and exhibit the maximising functions. Furthermore, using convenient trial functions, we derive lower bounds on for in many cases these are close to the previous upper bounds, as illustrated by a number of examples, thus characterizing the sharp constants with little uncertainty.

  10. On the constant-roll inflation

    Science.gov (United States)

    Yi, Zhu; Gong, Yungui

    2018-03-01

    The primordial power spectra of scalar and tensor perturbations during slow-roll inflation are usually calculated with the method of Bessel function approximation. For constant-roll or ultra slow-roll inflation, the method of Bessel function approximation may be invalid. We compare the numerical results with the analytical results derived from the Bessel function approximation, and we find that they differ significantly on super-horizon scales if the constant slow-roll parameter ηH is not small. More accurate method is needed for calculating the primordial power spectrum for constant-roll inflation.

  11. Scalar-tensor cosmology with cosmological constant

    International Nuclear Information System (INIS)

    Maslanka, K.

    1983-01-01

    The equations of scalar-tensor theory of gravitation with cosmological constant in the case of homogeneous and isotropic cosmological model can be reduced to dynamical system of three differential equations with unknown functions H=R/R, THETA=phi/phi, S=e/phi. When new variables are introduced the system becomes more symmetrical and cosmological solutions R(t), phi(t), e(t) are found. It is shown that when cosmological constant is introduced large class of solutions which depend also on Dicke-Brans parameter can be obtained. Investigations of these solutions give general limits for cosmological constant and mean density of matter in plane model. (author)

  12. Cosmological constant and advanced gravitational wave detectors

    International Nuclear Information System (INIS)

    Wang, Y.; Turner, E.L.

    1997-01-01

    Interferometric gravitational wave detectors could measure the frequency sweep of a binary inspiral (characterized by its chirp mass) to high accuracy. The observed chirp mass is the intrinsic chirp mass of the binary source multiplied by (1+z), where z is the redshift of the source. Assuming a nonzero cosmological constant, we compute the expected redshift distribution of observed events for an advanced LIGO detector. We find that the redshift distribution has a robust and sizable dependence on the cosmological constant; the data from advanced LIGO detectors could provide an independent measurement of the cosmological constant. copyright 1997 The American Physical Society

  13. Constant strength fuel-fuel cell

    International Nuclear Information System (INIS)

    Vaseen, V.A.

    1980-01-01

    A fuel cell is an electrochemical apparatus composed of both a nonconsumable anode and cathode; and electrolyte, fuel oxidant and controls. This invention guarantees the constant transfer of hydrogen atoms and their respective electrons, thus a constant flow of power by submergence of the negative electrode in a constant strength hydrogen furnishing fuel; when said fuel is an aqueous absorbed hydrocarbon, such as and similar to ethanol or methnol. The objective is accomplished by recirculation of the liquid fuel, as depleted in the cell through specific type membranes which pass water molecules and reject the fuel molecules; thus concentrating them for recycle use

  14. Reactor group constants and benchmark test

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Hideki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-08-01

    The evaluated nuclear data files such as JENDL, ENDF/B-VI and JEF-2 are validated by analyzing critical mock-up experiments for various type reactors and assessing applicability for nuclear characteristics such as criticality, reaction rates, reactivities, etc. This is called Benchmark Testing. In the nuclear calculations, the diffusion and transport codes use the group constant library which is generated by processing the nuclear data files. In this paper, the calculation methods of the reactor group constants and benchmark test are described. Finally, a new group constants scheme is proposed. (author)

  15. Geology and petrography in basaltic rocks (Arapey formation) cropping out in road 4 between Arapey river (92 km) and Artigas city (200 Km)

    International Nuclear Information System (INIS)

    Oyhantcabal, P.; Pineiro, G.

    2007-01-01

    This contribution presents a geological map of the basaltic flows of Arapey formation (Mezosoic) cropping out in Road 4 between the Arapey river (92 Km) and Artigas city (200 Km) together with the description of the petrographic features of the different portions of the 13 recognized flow units. (author)

  16. Future changes in the East Asian rain band projected by global atmospheric models with 20-km and 60-km grid size

    Energy Technology Data Exchange (ETDEWEB)

    Kusunoki, Shoji; Mizuta, Ryo [Meteorological Research Institute, Climate Research Department, Tsukuba, Ibaraki (Japan); Matsueda, Mio [Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Tsukuba, Ibaraki (Japan)

    2011-12-15

    Global warming projection experiments were conducted using a 20-km mesh global atmospheric model, focusing on the change in the rain band of East Asian summer monsoon. To assess the uncertainty of climate change projections, we performed ensemble simulations with the 60-km resolution model combining four different SSTs and three atmospheric initial conditions. In the present-day climate simulations, the 20-km model reproduces the rain band of East Asian summer monsoon better than lower resolution models in terms of geographical distribution and seasonal march. In the future climate simulation by the 20-km model, precipitation increases over the Yangtze River valley in May through July, Korean peninsula in May, and Japan in July. The termination of rainy season over Japan tends to be delayed until August. Ensemble simulations by the 60-km model show that precipitation in the future climate for July increases over the Yangtze River valley, the East China Sea and Japan. These changes in precipitation are partly consistent with those projected by the 20-km model. Simulations by the 20-km and 60-km models consistently show that in the future climate the termination of rainy season over Japan tends to be delayed until August. The changes in the vertically integrated water vapor flux show the intensification of clockwise moisture transport over the western Pacific subtropical high. Most precipitation changes over the East Asia can be interpreted as the moisture convergence resulting from change in the horizontal transport of water vapor. (orig.)

  17. Geology and petrography of the basaltic rocks (Arapey formation) cropping out in toad 4 between Arapey river (92 km) and Artigas (200 Km)

    International Nuclear Information System (INIS)

    Oyhantcabal, P.; Pineiro, G.

    2007-01-01

    This contribution presents a geological map of the basaltic flows of Arapey formation (Mezosoic) cropping out in Road 4 between the Arapey river (92 Km) and Artigas city (200 Km) together with the description of the petrographic features of the different portions of the 13 recognized flow units. (author)

  18. Geology and petrography in basaltic rocks (Arapey formation) cropping out in road 30 between the Bella Union round point (27 km) and Penas cuesta (225 Km)

    International Nuclear Information System (INIS)

    Oyhantcabal, P.; Pineiro, G.

    2007-01-01

    This contribution presents a geological map of the basaltic flows of Arapey formation (Mezosoic) cropping out in Road 30 between the Bella Union round point (27 Km) and Pena s cuesta (225 Km) together with the description of the petrographic features of the different portions of the 20 recognized flow units

  19. Relationship between electrophilicity index, Hammett constant and ...

    Indian Academy of Sciences (India)

    Unknown

    Inter-relationships between the electrophilicity index (ω), Hammett constant (óp) and nucleus- independent chemical ... cess of DFT is that it provides simple working equa- tions to elucidate ... compasses both the ability of an electrophile to ac-.

  20. Canonoid transformations and constants of motion

    International Nuclear Information System (INIS)

    Negri, L.J.; Oliveira, L.C.; Teixeira, J.M.

    1986-01-01

    The necessary and sufficient conditions for a canonoid transformation with respect to a given Hamiltonian are obtained in terms of the Lagrange brackets of the trasformation. The relation of these conditions with the constants of motion is discussed. (Author) [pt

  1. An improved dosimeter having constant flow pump

    International Nuclear Information System (INIS)

    Baker, W.B.

    1980-01-01

    A dosemeter designed for individual use which can be used to monitor toxic radon gas and toxic related products of radon gas in mines and which incorporates a constant air stream flowing through the dosimeter is described. (U.K.)

  2. Interacting universes and the cosmological constant

    International Nuclear Information System (INIS)

    Alonso-Serrano, A.; Bastos, C.; Bertolami, O.; Robles-Pérez, S.

    2013-01-01

    In this Letter it is studied the effects that an interaction scheme among universes can have in the values of their cosmological constants. In the case of two interacting universes, the value of the cosmological constant of one of the universes becomes very close to zero at the expense of an increasing value of the cosmological constant of the partner universe. In the more general case of a chain of N interacting universes with periodic boundary conditions, the spectrum of the Hamiltonian splits into a large number of levels, each of them associated with a particular value of the cosmological constant, that can be occupied by single universes revealing a collective behavior that plainly shows that the multiverse is much more than the mere sum of its parts

  3. Interacting universes and the cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-Serrano, A. [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado 14, 06411 Medellín (Spain); Bastos, C. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bertolami, O. [Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Robles-Pérez, S., E-mail: salvarp@imaff.cfmac.csic.es [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado 14, 06411 Medellín (Spain); Física Teórica, Universidad del País Vasco, Apartado 644, 48080 Bilbao (Spain)

    2013-02-12

    In this Letter it is studied the effects that an interaction scheme among universes can have in the values of their cosmological constants. In the case of two interacting universes, the value of the cosmological constant of one of the universes becomes very close to zero at the expense of an increasing value of the cosmological constant of the partner universe. In the more general case of a chain of N interacting universes with periodic boundary conditions, the spectrum of the Hamiltonian splits into a large number of levels, each of them associated with a particular value of the cosmological constant, that can be occupied by single universes revealing a collective behavior that plainly shows that the multiverse is much more than the mere sum of its parts.

  4. Constant conditional entropy and related hypotheses

    International Nuclear Information System (INIS)

    Ferrer-i-Cancho, Ramon; Dębowski, Łukasz; Moscoso del Prado Martín, Fermín

    2013-01-01

    Constant entropy rate (conditional entropies must remain constant as the sequence length increases) and uniform information density (conditional probabilities must remain constant as the sequence length increases) are two information theoretic principles that are argued to underlie a wide range of linguistic phenomena. Here we revise the predictions of these principles in the light of Hilberg’s law on the scaling of conditional entropy in language and related laws. We show that constant entropy rate (CER) and two interpretations for uniform information density (UID), full UID and strong UID, are inconsistent with these laws. Strong UID implies CER but the reverse is not true. Full UID, a particular case of UID, leads to costly uncorrelated sequences that are totally unrealistic. We conclude that CER and its particular cases are incomplete hypotheses about the scaling of conditional entropies. (letter)

  5. New perspectives on constant-roll inflation

    Science.gov (United States)

    Cicciarella, Francesco; Mabillard, Joel; Pieroni, Mauro

    2018-01-01

    We study constant-roll inflation using the β-function formalism. We show that the constant rate of the inflaton roll is translated into a first order differential equation for the β-function which can be solved easily. The solutions to this equation correspond to the usual constant-roll models. We then construct, by perturbing these exact solutions, more general classes of models that satisfy the constant-roll equation asymptotically. In the case of an asymptotic power law solution, these corrections naturally provide an end to the inflationary phase. Interestingly, while from a theoretical point of view (in particular in terms of the holographic interpretation) these models are intrinsically different from standard slow-roll inflation, they may have phenomenological predictions in good agreement with present cosmological data.

  6. Hydrolysis and formation constants at 250C

    International Nuclear Information System (INIS)

    Phillips, S.L.

    1982-05-01

    A database consisting of hydrolysis and formation constants for about 20 metals associated with the disposal of nuclear waste is given. Complexing ligands for the various ionic species of these metals include OH, F, Cl, SO 4 , PO 4 and CO 3 . Table 1 consists of tabulated calculated and experimental values of log K/sub xy/, mainly at 25 0 C and various ionic strengths together with references to the origin of the data. Table 2 consists of a column of recommended stability constants at 25 0 C and zero ionic strength tabulated in the column headed log K/sub xy/(0); other columns contain coefficients for an extended Debye-Huckel equation to permit calculations of stability constants up to 3 ionic strength, and up to 0.7 ionic strength using the Davies equation. Selected stability constants calculated with these coefficients for various ionic strengths agree to an average of +- 2% when compared with published experimental and calculated values

  7. Wormholes and the cosmological constant problem.

    Science.gov (United States)

    Klebanov, I.

    The author reviews the cosmological constant problem and the recently proposed wormhole mechanism for its solution. Summation over wormholes in the Euclidean path integral for gravity turns all the coupling parameters into dynamical variables, sampled from a probability distribution. A formal saddle point analysis results in a distribution with a sharp peak at the cosmological constant equal to zero, which appears to solve the cosmological constant problem. He discusses the instabilities of the gravitational Euclidean path integral and the difficulties with its interpretation. He presents an alternate formalism for baby universes, based on the "third quantization" of the Wheeler-De Witt equation. This approach is analyzed in a minisuperspace model for quantum gravity, where it reduces to simple quantum mechanics. Once again, the coupling parameters become dynamical. Unfortunately, the a priori probability distribution for the cosmological constant and other parameters is typically a smooth function, with no sharp peaks.

  8. Building evolutionary architectures support constant change

    CERN Document Server

    Ford, Neal; Kua, Patrick

    2017-01-01

    The software development ecosystem is constantly changing, providing a constant stream of new tools, frameworks, techniques, and paradigms. Over the past few years, incremental developments in core engineering practices for software development have created the foundations for rethinking how architecture changes over time, along with ways to protect important architectural characteristics as it evolves. This practical guide ties those parts together with a new way to think about architecture and time.

  9. Nuclei quadrupole coupling constants in diatomic molecule

    International Nuclear Information System (INIS)

    Ivanov, A.I.; Rebane, T.K.

    1993-01-01

    An approximate relationship between the constants of quadrupole interaction of nuclei in a two-atom molecule is found. It enabled to establish proportionality of oscillatory-rotation corrections to these constants for both nuclei in the molecule. Similar results were obtained for the factors of electrical dipole-quadrupole screening of nuclei. Applicability of these relationships is proven by the example of lithium deuteride molecule. 4 refs., 1 tab

  10. Parametrised Constants and Replication for Spatial Mobility

    DEFF Research Database (Denmark)

    Hüttel, Hans; Haagensen, Bjørn

    2009-01-01

    Parametrised replication and replication are common ways of expressing infinite computation in process calculi. While parametrised constants can be encoded using replication in the π-calculus, this changes in the presence of spatial mobility as found in e.g. the distributed π- calculus...... of the distributed π-calculus with parametrised constants and replication are incomparable. On the other hand, we shall see that there exists a simple encoding of recursion in mobile ambients....

  11. A model for solar constant secular changes

    Science.gov (United States)

    Schatten, Kenneth H.

    1988-01-01

    In this paper, contrast models for solar active region and global photospheric features are used to reproduce the observed Active Cavity Radiometer and Earth Radiation Budget secular trends in reasonably good fashion. A prediction for the next decade of solar constant variations is made using the model. Secular trends in the solar constant obtained from the present model support the view that the Maunder Minimum may be related to the Little Ice Age of the 17th century.

  12. A quadri-constant fraction discriminator

    International Nuclear Information System (INIS)

    Wang Wei; Gu Zhongdao

    1992-01-01

    A quad Constant Fraction (Amplitude and Rise Time Compensation) Discriminator Circuit is described, which is based on the ECL high-speed dual comparator AD 9687. The CFD (ARCD) is of the constant fraction timing type (the amplitude and rise time compensation timing type) employing a leading edge discriminator to eliminate error triggers caused by noises. A timing walk measurement indicates a timing walk of less than +- 150 ps from -50 mV to -5 V

  13. Renormalization group equations with multiple coupling constants

    International Nuclear Information System (INIS)

    Ghika, G.; Visinescu, M.

    1975-01-01

    The main purpose of this paper is to study the renormalization group equations of a renormalizable field theory with multiple coupling constants. A method for the investigation of the asymptotic stability is presented. This method is applied to a gauge theory with Yukawa and self-quartic couplings of scalar mesons in order to find the domains of asymptotic freedom. An asymptotic expansion for the solutions which tend to the origin of the coupling constants is given

  14. Inflation with a constant rate of roll

    International Nuclear Information System (INIS)

    Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi

    2015-01-01

    We consider an inflationary scenario where the rate of inflaton roll defined by ·· φ/H φ-dot remains constant. The rate of roll is small for slow-roll inflation, while a generic rate of roll leads to the interesting case of 'constant-roll' inflation. We find a general exact solution for the inflaton potential required for such inflaton behaviour. In this model, due to non-slow evolution of background, the would-be decaying mode of linear scalar (curvature) perturbations may not be neglected. It can even grow for some values of the model parameter, while the other mode always remains constant. However, this always occurs for unstable solutions which are not attractors for the given potential. The most interesting particular cases of constant-roll inflation remaining viable with the most recent observational data are quadratic hilltop inflation (with cutoff) and natural inflation (with an additional negative cosmological constant). In these cases even-order slow-roll parameters approach non-negligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime

  15. RNA structure and scalar coupling constants

    Energy Technology Data Exchange (ETDEWEB)

    Tinoco, I. Jr.; Cai, Z.; Hines, J.V.; Landry, S.M.; SantaLucia, J. Jr.; Shen, L.X.; Varani, G. [Univ. of California, Berkeley, CA (United States)

    1994-12-01

    Signs and magnitudes of scalar coupling constants-spin-spin splittings-comprise a very large amount of data that can be used to establish the conformations of RNA molecules. Proton-proton and proton-phosphorus splittings have been used the most, but the availability of {sup 13}C-and {sup 15}N-labeled molecules allow many more coupling constants to be used for determining conformation. We will systematically consider the torsion angles that characterize a nucleotide unit and the coupling constants that depend on the values of these torsion angles. Karplus-type equations have been established relating many three-bond coupling constants to torsion angles. However, one- and two-bond coupling constants can also depend on conformation. Serianni and coworkers measured carbon-proton coupling constants in ribonucleosides and have calculated their values as a function of conformation. The signs of two-bond coupling can be very useful because it is easier to measure a sign than an accurate magnitude.

  16. The prototype detection unit of the KM3NeT detector

    NARCIS (Netherlands)

    Adrian-Martinez, S.; Ageron, M.; Aharonian, F.; Aiello, S.; Albert, A.; Ameli, F.; Anassontzis, E. G.; Androulakis, G. C.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Avgitas, T.; Balasi, K.; Band, H.; Barbarino, G.; Barbarito, E.; Barbato, F.; Baret, B.; Baron, S.; Barrios, J.; Belias, A.; Berbee, E.; van den Berg, A. M.; Berkien, A.; Bertin, V.; Beurthey, S.; van Beveren, V.; Beverini, N.; Biagi, S.; Biagioni, A.; Bianucci, S.; Billault, M.; Birbas, A.; Rookhuizen, H. Boer; Bormuth, R.; Bouche, V.; Bouhadef, B.; Bourlis, G.; Boutonnet, C.; Bouwhuis, M.; Bozza, C.; Bruijn, R.; Brunner, J.; Cacopardo, G.; Dorosti-Hasankiadeh, Q.; Hevinga, M. A.; Kavatsyuk, O.; Löhner, H.; van Wooning, R. H. L.

    2016-01-01

    A prototype detection unit of the KM3NeT deep-sea neutrino telescope has been installed at 3500m depth 80 km offshore the Italian coast. KM3NeT in its final configuration will contain several hundreds of detection units. Each detection unit is a mechanical structure anchored to the sea floor, held

  17. Underwater acoustic positioning system for the SMO and KM3NeT - Italia projects

    Energy Technology Data Exchange (ETDEWEB)

    Viola, S.; Barbagallo, G.; Cacopardo, G.; Calí, C.; Cocimano, R.; Coniglione, R.; Costa, M.; Cuttone, G.; D' Amato, C.; D' Amato, V.; D' Amico, A.; De Luca, V.; Del Tevere, F.; Distefano, C.; Ferrera, F.; Gmerk, A.; Grasso, R.; Imbesi, M.; Larosa, G.; Lattuada, D. [INFN - Laboratori Nazionali del Sud, via Santa Sofia 62, 95125 Catania (Italy); and others

    2014-11-18

    In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their movements must be known with an accuracy of few tens of centimetres. In this work, the activities of the SMO and KM3NeT-Italia teams for the development of an acoustic positioning system for KM3NeT-Italia project are presented. The KM3NeT-Italia project foresees the construction, within two years, of 8 towers in the view of the several km{sup 3}-scale neutrino telescope KM3NeT.

  18. Underwater acoustic positioning system for the SMO and KM3NeT - Italia projects

    International Nuclear Information System (INIS)

    Viola, S.; Barbagallo, G.; Cacopardo, G.; Calí, C.; Cocimano, R.; Coniglione, R.; Costa, M.; Cuttone, G.; D'Amato, C.; D'Amato, V.; D'Amico, A.; De Luca, V.; Del Tevere, F.; Distefano, C.; Ferrera, F.; Gmerk, A.; Grasso, R.; Imbesi, M.; Larosa, G.; Lattuada, D.

    2014-01-01

    In the underwater neutrino telescopes, the positions of the Cherenkov light sensors and their movements must be known with an accuracy of few tens of centimetres. In this work, the activities of the SMO and KM3NeT-Italia teams for the development of an acoustic positioning system for KM3NeT-Italia project are presented. The KM3NeT-Italia project foresees the construction, within two years, of 8 towers in the view of the several km 3 -scale neutrino telescope KM3NeT

  19. An overview of knowledge management (KM) issues for implementation in consultant firms in Malaysian construction industry

    Science.gov (United States)

    Othman, Azlan; Ismail, Syuhaida; Yahya, Khairulzan

    2017-12-01

    In the past few years, there has been a growing interest in treating knowledge as a significant organisational resource. Thus, effective development and implementation of KM requires a foundation in several rich literatures. As a preparation for the competitive industrial nation, KM is an important countenance that should be the point of convergence for the industry players. This paper wishes to draw the attention on the current situation of KM practice, focusing on consultant firms in Malaysian construction industry. Questionnaires were distributed to about 200 respondents working in the industry, with the objective of appraising the KM implementation amongst consultant firms working in construction industry in Malaysia. This paper also gives the overview on KM definition, process, understanding and challenges in construction industry, besides the critical success factor of KM implementation. The literature is restricted on the recent KM study of 17 years research from 2000 to 2017. Finally, this paper proposes the conceptual ideas of relationship between KM process, KM understanding and KM challenges with critical success factor of KM implementation.

  20. Determination of Methane and Carbon Dioxide Formation Rate Constants for Semi-Continuously Fed Anaerobic Digesters

    Directory of Open Access Journals (Sweden)

    Jan Moestedt

    2015-01-01

    Full Text Available To optimize commercial-scale biogas production, it is important to evaluate the performance of each microbial step in the anaerobic process. Hydrolysis and methanogenesis are usually the rate-limiting steps during digestion of organic waste and by-products. By measuring biogas production and methane concentrations on-line in a semi-continuously fed reactor, gas kinetics can be evaluated. In this study, the rate constants of the fermentative hydrolysis step (kc and the methanogenesis step (km were determined and evaluated in a continuously stirred tank laboratory-scale reactor treating food and slaughterhouse waste and glycerin. A process additive containing Fe2+, Co2+ and Ni2+ was supplied until day 89, after which Ni2+ was omitted. The omission resulted in a rapid decline in the methanogenesis rate constant (km to 70% of the level observed when Ni2+ was present, while kc remained unaffected. This suggests that Ni2+ mainly affects the methanogenic rather than the hydrolytic microorganisms in the system. However, no effect was initially observed when using conventional process monitoring parameters such as biogas yield and volatile fatty acid concentration. Hence, formation rate constants can reveal additional information on process performance and km can be used as a complement to conventional process monitoring tools for semi-continuously fed anaerobic digesters.

  1. Constant-roll (quasi-)linear inflation

    Science.gov (United States)

    Karam, A.; Marzola, L.; Pappas, T.; Racioppi, A.; Tamvakis, K.

    2018-05-01

    In constant-roll inflation, the scalar field that drives the accelerated expansion of the Universe is rolling down its potential at a constant rate. Within this framework, we highlight the relations between the Hubble slow-roll parameters and the potential ones, studying in detail the case of a single-field Coleman-Weinberg model characterised by a non-minimal coupling of the inflaton to gravity. With respect to the exact constant-roll predictions, we find that assuming an approximate slow-roll behaviour yields a difference of Δ r = 0.001 in the tensor-to-scalar ratio prediction. Such a discrepancy is in principle testable by future satellite missions. As for the scalar spectral index ns, we find that the existing 2-σ bound constrains the value of the non-minimal coupling to ξphi ~ 0.29–0.31 in the model under consideration.

  2. Cosmological constant is a conserved charge

    Science.gov (United States)

    Chernyavsky, Dmitry; Hajian, Kamal

    2018-06-01

    Cosmological constant can always be considered as the on-shell value of a top form in gravitational theories. The top form is the field strength of a gauge field, and the theory enjoys a gauge symmetry. We show that cosmological constant is the charge of the global part of the gauge symmetry, and is conserved irrespective of the dynamics of the metric and other fields. In addition, we introduce its conjugate chemical potential, and prove the generalized first law of thermodynamics which includes variation of cosmological constant as a conserved charge. We discuss how our new term in the first law is related to the volume–pressure term. In parallel with the seminal Wald entropy, this analysis suggests that pressure can also be considered as a conserved charge.

  3. Fast optimization algorithms and the cosmological constant

    Science.gov (United States)

    Bao, Ning; Bousso, Raphael; Jordan, Stephen; Lackey, Brad

    2017-11-01

    Denef and Douglas have observed that in certain landscape models the problem of finding small values of the cosmological constant is a large instance of a problem that is hard for the complexity class NP (Nondeterministic Polynomial-time). The number of elementary operations (quantum gates) needed to solve this problem by brute force search exceeds the estimated computational capacity of the observable Universe. Here we describe a way out of this puzzling circumstance: despite being NP-hard, the problem of finding a small cosmological constant can be attacked by more sophisticated algorithms whose performance vastly exceeds brute force search. In fact, in some parameter regimes the average-case complexity is polynomial. We demonstrate this by explicitly finding a cosmological constant of order 10-120 in a randomly generated 1 09-dimensional Arkani-Hamed-Dimopoulos-Kachru landscape.

  4. Conformally invariant braneworld and the cosmological constant

    International Nuclear Information System (INIS)

    Guendelman, E.I.

    2004-01-01

    A six-dimensional braneworld scenario based on a model describing the interaction of gravity, gauge fields and 3+1 branes in a conformally invariant way is described. The action of the model is defined using a measure of integration built of degrees of freedom independent of the metric. There is no need to fine tune any bulk cosmological constant or the tension of the two (in the scenario described here) parallel branes to obtain zero cosmological constant, the only solutions are those with zero 4D cosmological constant. The two extra dimensions are compactified in a 'football' fashion and the branes lie on the two opposite poles of the compact 'football-shaped' sphere

  5. Vanishing cosmological constant in elementary particles theory

    International Nuclear Information System (INIS)

    Pisano, F.; Tonasse, M.D.

    1997-01-01

    The quest of a vanishing cosmological constant is considered in the simplest anomaly-free chiral gauge extension of the electroweak standard model where the new physics is limited to a well defined additional flavordynamics above the Fermi scale, namely up to a few TeVs by matching the gauge coupling constants at the electroweak scale, and with an extended Higgs structure. In contrast to the electroweak standard model, it is shown how the extended scalar sector of the theory allows a vanishing or a very small cosmological constant. the details of the cancellation mechanism are presented. At accessible energies the theory is indistinguishable from the standard model of elementary particles and it is in agreement with all existing data. (author). 32 refs

  6. Stability constants for silicate adsorbed to ferrihydrite

    DEFF Research Database (Denmark)

    Hansen, Hans Christian Bruun; Wetche, T.P.; Raulund-Rasmussen, Karsten

    1994-01-01

    Intrinsic surface acidity constants (K(a1)intr, K(a2)intr) and surface complexation constant for adsorption of orthosilicate onto synthetic ferrihydrite (K(Si) for the complex = FeOSi(OH)3) have been determined from acid/base titrations in 0.001-0.1 m NaClO4 electrolytes and silicate adsorption...... experiments in 0.01 m NaNO3 electrolyte (pH 3-6). The surface equilibrium constants were calculated according to the two-layer model by Dzombak & Morel (1990). Near equilibrium between protons/hydroxyls in solution and the ferrihydrite surface was obtained within minutes while equilibration with silicate...

  7. Derivation of the optical constants of anisotropic

    Science.gov (United States)

    Aronson, J. R.; Emslie, A. G.; Smith, E. M.; Strong, P. F.

    1985-07-01

    This report concerns the development of methods for obtaining the optical constants of anisotropic crystals of the triclinic and monoclinic systems. The principal method used, classical dispersion theory, is adapted to these crystal systems by extending the Lorentz line parameters to include the angles characterizing the individual resonances, and by replacing the dielectric constant by a dielectric tensor. The sample crystals are gypsium, orthoclase and chalcanthite. The derived optical constants are shown to be suitable for modeling the optical properties of particulate media in the infrared spectral region. For those materials where suitable size single crystals are not available, an extension of a previously used method is applied to alabaster, a polycrystalline material of the monoclinic crystal system.

  8. Effects of quantum entropy on bag constant

    International Nuclear Information System (INIS)

    Miller, D.E.; Tawfik, A.

    2012-01-01

    The effects of quantum entropy on the bag constant are studied at low temperatures and for small chemical potentials. The inclusion of the quantum entropy of the quarks in the equation of state provides the hadronic bag with an additional heat which causes a decrease in the effective latent heat inside the bag. We have considered two types of baryonic bags, Δ and Ω - . In both cases we have found that the bag constant without the quantum entropy almost does not change with temperature and quark chemical potential. The contribution from the quantum entropy to the equation of state clearly decreases the value of the bag constant. Furthermore, we construct states densities for quarks using the 'Thomas Fermi model' and take into consideration a thermal potential for the interaction. (author)

  9. 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.

  10. The Cosmological Constant Problem (1/2)

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    I will review the cosmological constant problem as a serious challenge to our notion of naturalness in Physics. Weinberg’s no go theorem is worked through in detail. I review a number of proposals possibly including Linde's universe multiplication, Coleman's wormholes, the fat graviton, and SLED, to name a few. Large distance modifications of gravity are also discussed, with causality considerations pointing towards a global modification as being the most sensible option. The global nature of the cosmological constant problem is also emphasized, and as a result, the sequestering scenario is reviewed in some detail, demonstrating the cancellation of the Standard Model vacuum energy through a global modification of General Relativity.

  11. The Cosmological Constant Problem (2/2)

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    I will review the cosmological constant problem as a serious challenge to our notion of naturalness in Physics. Weinberg’s no go theorem is worked through in detail. I review a number of proposals possibly including Linde's universe multiplication, Coleman's wormholes, the fat graviton, and SLED, to name a few. Large distance modifications of gravity are also discussed, with causality considerations pointing towards a global modification as being the most sensible option. The global nature of the cosmological constant problem is also emphasized, and as a result, the sequestering scenario is reviewed in some detail, demonstrating the cancellation of the Standard Model vacuum energy through a global modification of General Relativity.

  12. Atomic weights: no longer constants of nature

    Science.gov (United States)

    Coplen, Tyler B.; Holden, Norman E.

    2011-01-01

    Many of us were taught that the standard atomic weights we found in the back of our chemistry textbooks or on the Periodic Table of the Chemical Elements hanging on the wall of our chemistry classroom are constants of nature. This was common knowledge for more than a century and a half, but not anymore. The following text explains how advances in chemical instrumentation and isotopic analysis have changed the way we view atomic weights and why they are no longer constants of nature

  13. [An oral chemical vaccine from the hypertoxigenic strains of the causative agent of cholera KM-76 Inaba and KM-68 Ogawa].

    Science.gov (United States)

    Dzhaparidze, M N; Naumov, A V; Nikitina, G P; Meleshchenko, M V; Dobrova, G V; Zavorotnykh, V I; Gracheva, V P; Zakharova, T L

    1991-04-01

    The material on the development of chemical vaccine, prepared from two newly formed strains (KM-76 Inaba and KM-68 Ogawa) and intended for oral administration, is presented. The conditions for the submerged cultivation of these strains have been established, which makes it possible to increase the production of choleragen 8- to 10-fold and O-antigen 3- to 4-fold in comparison with V. cholerae natural strain 569B. The maximum accumulation of neuraminidase, protease, phospholipase, along with choleragen, has been registered in the logarithmic phase and that of O-antigen, in the stationary phase of growth. The use of strains KM-76 and KM-68 has led to the fourfold increase of the specific activity of the main immunogens, thus permitting the respective increase of the yield of the oral vaccine without changes in its high capacity for the formation of specific antibodies and its low residual toxigenicity.

  14. Metabolic evaluation of Crioulo horses participating in competitions of 750 km

    Directory of Open Access Journals (Sweden)

    Lorena Alvariza Amaral

    2013-12-01

    Full Text Available The Crioulo breed of horses performs in one of the most physically demanding equestrian competitions, the Marcha de Resistência, which is a contest in which the horses run 750 km in 15 days. The study's aim was to characterize the metabolic responses during this period. We evaluated eleven Crioulo horses in the competition, specifically, two males and nine females. Blood samples were collected 24 hours before the contest and on the 4th, 9th, 11th, 14th and 15th days of competition. We evaluated CK, AST, LDH, glucose, lactate, urea, creatinine, sodium, potassium, chloride, magnesium, total calcium, ionized calcium, total protein, hematocrit and the white blood cell count. At the end of the competition, the mean values of serum AST were 1151±358 IU/ L the mean LDH values were 7418±1695 IU/L and CK was 13,867±3998UI /L. There was a significant increase in urea, creatinine and lactate (p<0.0001. A decrease in the mean values of chloride, sodium, potassium, and total and ionized calcium was observed (p≤0.0002. An evaluation of the total leukocytes and segmented neutrophils (p≤0.0002 revealed their increased values, and decreased values were observed for hematocrit, plasma protein and total lymphocytes (p≤0.0003. The values of glucose, on average, remained constant. Based on these data, we conclude that the Marcha de Resistência competition necessitated a high muscular demand and the depletion of energy and electrolytes, suggesting an inflammatory process in the animals evaluated.

  15. Mimicking the cosmological constant: Constant curvature spherical solutions in a nonminimally coupled model

    International Nuclear Information System (INIS)

    Bertolami, Orfeu; Paramos, Jorge

    2011-01-01

    The purpose of this study is to describe a perfect fluid matter distribution that leads to a constant curvature region, thanks to the effect of a nonminimal coupling. This distribution exhibits a density profile within the range found in the interstellar medium and an adequate matching of the metric components at its boundary. By identifying this constant curvature with the value of the cosmological constant and superimposing the spherical distributions arising from different matter sources throughout the universe, one is able to mimic a large-scale homogeneous cosmological constant solution.

  16. Time constant of logarithmic creep and relaxation

    CSIR Research Space (South Africa)

    Nabarro, FRN

    2001-07-15

    Full Text Available length and hardness which vary logarithmically with time. For dimensional reasons, a logarithmic variation must involve a time constant tau characteristic of the process, so that the deformation is proportional to ln(t/tau). Two distinct mechanisms...

  17. The Nature of the Cosmological Constant Problem

    Science.gov (United States)

    Maia, M. D.; Capistrano, A. J. S.; Monte, E. M.

    General relativity postulates the Minkowski space-time as the standard (flat) geometry against which we compare all curved space-times and also as the gravitational ground state where particles, quantum fields and their vacua are defined. On the other hand, experimental evidences tell that there exists a non-zero cosmological constant, which implies in a deSitter ground state, which not compatible with the assumed Minkowski structure. Such inconsistency is an evidence of the missing standard of curvature in Riemann's geometry, which in general relativity manifests itself in the form of the cosmological constant problem. We show how the lack of a curvature standard in Riemann's geometry can be fixed by Nash's theorem on metric perturbations. The resulting higher dimensional gravitational theory is more general than general relativity, similar to brane-world gravity, but where the propagation of the gravitational field along the extra dimensions is a mathematical necessity, rather than a postulate. After a brief introduction to Nash's theorem, we show that the vacuum energy density must remain confined to four-dimensional space-times, but the cosmological constant resulting from the contracted Bianchi identity represents a gravitational term which is not confined. In this case, the comparison between the vacuum energy and the cosmological constant in general relativity does not make sense. Instead, the geometrical fix provided by Nash's theorem suggests that the vacuum energy density contributes to the perturbations of the gravitational field.

  18. A Memorandum Report: Physical Constants of MCE

    Science.gov (United States)

    2016-08-01

    the density and surface tension. In effect, this constant is a corrected molar volume = P = MS / = S / where P = Parachor M = molar volume ...3 3. Vapor Pressure of MCE Calculated from the Experimental Data by Method of Least Squares...values were obtained by averaging the determinations for each sample separately, and then averaging those values. **No average was calculated due to

  19. Study on electromagnetic constants of rotational bands

    International Nuclear Information System (INIS)

    Abdurazakov, A.A.; Adib, Yu.Sh.; Karakhodzhaev, A.K.

    1991-01-01

    Values of electromagnetic constant S and rotation bands of odd nuclei with Z=64-70 within the mass number change interval A=153-173 are determined. Values of γ-transition mixing parameter with M1+E2 multipolarity are presented. ρ parameter dependence on mass number A is discussed

  20. On the determination of the Hubble constant

    International Nuclear Information System (INIS)

    Gurzadyan, V.G.; Harutyunyan, V.V.; Kocharyan, A.A.

    1990-10-01

    The possibility of an alternative determination of the distance scale of the Universe and the Hubble constant based on the numerical analysis of the hierarchical nature of the large scale Universe (galaxies, clusters and superclusters) is proposed. The results of computer experiments performed by means of special numerical algorithms are represented. (author). 9 refs, 7 figs

  1. Dissociative electron attachment to ozone: rate constant

    International Nuclear Information System (INIS)

    Skalny, J.D.; Cicman, P.; Maerk, T.D.

    2002-01-01

    The rate constant for dissociative electron attachment to ozone has been derived over the energy range of 0-10 eV by using previously measured cross section data revisited here in regards to discrimination effect occurring during the extraction of ions. The obtained data for both possible channels exhibit the maximum at mean electron energies close to 1 eV. (author)

  2. Running coupling constants of the Luttinger liquid

    International Nuclear Information System (INIS)

    Boose, D.; Jacquot, J.L.; Polonyi, J.

    2005-01-01

    We compute the one-loop expressions of two running coupling constants of the Luttinger model. The obtained expressions have a nontrivial momentum dependence with Landau poles. The reason for the discrepancy between our results and those of other studies, which find that the scaling laws are trivial, is explained

  3. Constant force linear permanent magnet actuators

    NARCIS (Netherlands)

    Paulides, J.J.H.; Encica, L.; Meessen, K.J.; Lomonova, E.A.

    2009-01-01

    In applications, such as vibration isolation, gravity compensation, pick-and-place machines, etc., there is a need for (long-stroke) passive constant force actuators combined with tubular permanent magnet actuators to minimize the power consumption, hence, passively counteract the gravitational

  4. Lifetime of titanium filament at constant current

    International Nuclear Information System (INIS)

    Chou, T.S.; Lanni, C.

    1981-01-01

    Titanium Sublimation Pump (TSP) represents the most efficient and the least expensive method to produce Ultra High Vacuum (UHV) in storage rings. In ISABELLE, a proton storage accelerator under construction at Brookhaven National Laboratory, for example, TSP provides a pumping speed for hydrogen of > 2 x 10 6 l/s. Due to the finite life of titanium filaments, new filaments have to be switched in before the end of filament burn out, to ensure smooth operation of the accelerator. Therefore, several operational modes that can be used to activate the TSP were studied. The constant current mode is a convenient way of maintaining constant evaporating rate by increasing the power input while the filament diameter decreases as titanium evaporates. The filaments used in this experiment were standard Varian 916-0024 filaments made of Ti 85%, Mo 15% alloy. During their lifetime at a constant current of 48 amperes, the evaporation rate rose to a maximum at about 10% of their life and then flattened out to a constant value, 0.25 g/hr. The maximum evaporation rate occurs coincidently with the recrystallization of 74% Ti 26% Mo 2 from microstructure crystalline at higher titanium concentration to macrostructure crystalline at lower titanium concentration. As the macrocrystal grows, the slip plane develops at the grain boundary resulting in high resistance at the slip plane which will eventually cause the filament burn out due to local heating

  5. Derivation of the fine-structure constant

    International Nuclear Information System (INIS)

    Samec, A.

    1980-01-01

    The fine-structure constant is derived as a dynamical property of quantum electrodynamics. Single-particle solutions of the coupled Maxwell and Dirac equations have a physical charge spectrum. The solutions are used to construct lepton-and quark-like particles. The strong, weak, electromagnetic, and gravitational forces are described as the interactions of complex charges in multiple combinations

  6. Administration of exercise-conditioned plasma alters muscle catalase kinetics in rat: An argument for in vivo-like Km instead of in vitro-like Vmax

    Directory of Open Access Journals (Sweden)

    Aristidis S. Veskoukis

    2018-05-01

    Full Text Available Maximal velocity (Vmax is a well established biomarker for the assessment of tissue redox status. There is scarce evidence, though, that it does not probably reflect sufficiently in vivo tissue redox profile. Instead, the Michaelis constant (Km could more adequately image tissue oxidative stress and, thus, be a more physiologically relevant redox biomarker. Therefore, the aim of the present study was to side-by-side compare Vmax and Km of an antioxidant enzyme after implementing an in vivo set up that induces alterations in tissue redox status. Forty rats were divided into two groups including rats injected with blood plasma originating from rats that had previously swam until exhaustion and rats injected with blood plasma originating from sedentary rats. Tail-vein injections were performed daily for 21 days. Catalase Vmax and Km measured in gastrocnemius muscle were increased after administration of the exercise-conditioned plasma, denoting enhancement of the enzyme activity but impairment of its affinity for the substrate, respectively. These alterations are potential adaptations stimulated by the administered plasma pointing out that blood is an active fluid capable of regulating tissue homeostasis. Our findings suggest that Km adequately reflects in vivo modifications of skeletal muscle catalase and seems to surpass Vmax regarding its physiological relevance and biological interpretation. In conclusion, Km can be regarded as an in vivo-like biomarker that satisfactorily images the intracellular environment, as compared to Vmax that could be aptly parallelized with a biomarker that describes tissue oxidative stress in an in vitro manner.

  7. 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.

  8. Seismic Observations Indicating That the 2015 Ogasawara (Bonin) Earthquake Ruptured Beneath the 660 km Discontinuity

    Science.gov (United States)

    Kuge, Keiko

    2017-11-01

    The termination of deep earthquakes at a depth of 700 km is a key feature for understanding the physical mechanism of deep earthquakes. The 680 km deep 30 May 2015, Ogasawara (Bonin) earthquake (Mw 7.9) and its aftershocks were recorded by seismic stations at distances from 7° to 19°. Synthetic seismograms indicate that the P waveforms depend on whether the earthquake is located above or below the 660 km discontinuity. In this study, I show that broadband recordings indicate that the 2015 earthquake may have occurred below the 660 km velocity discontinuity. Recordings of the P wave from the strongest aftershock lack evidence for wave triplication expected when a subhorizontal discontinuity underlies the hypocenter. Theoretical waveforms computed with a 660 km discontinuity above the aftershock and mainshock match the observed waveforms more accurately. These observations may indicate earthquake ruptures due to mantle minerals other than olivine or strong deformation of the 660 km phase transition.

  9. Construction of Lines of Constant Density and Constant Refractive Index for Ternary Liquid Mixtures.

    Science.gov (United States)

    Tasic, Aleksandar Z.; Djordjevic, Bojan D.

    1983-01-01

    Demonstrates construction of density constant and refractive index constant lines in triangular coordinate system on basis of systematic experimental determinations of density and refractive index for both homogeneous (single-phase) ternary liquid mixtures (of known composition) and the corresponding binary compositions. Background information,…

  10. Molecular equilibrium structures from experimental rotational constants and calculated vibration-rotation interaction constants

    DEFF Research Database (Denmark)

    Pawlowski, F; Jorgensen, P; Olsen, Jeppe

    2002-01-01

    A detailed study is carried out of the accuracy of molecular equilibrium geometries obtained from least-squares fits involving experimental rotational constants B(0) and sums of ab initio vibration-rotation interaction constants alpha(r)(B). The vibration-rotation interaction constants have been...... calculated for 18 single-configuration dominated molecules containing hydrogen and first-row atoms at various standard levels of ab initio theory. Comparisons with the experimental data and tests for the internal consistency of the calculations show that the equilibrium structures generated using Hartree......-Fock vibration-rotation interaction constants have an accuracy similar to that obtained by a direct minimization of the CCSD(T) energy. The most accurate vibration-rotation interaction constants are those calculated at the CCSD(T)/cc-pVQZ level. The equilibrium bond distances determined from these interaction...

  11. Developing a Maturity Model for Knowledge Management (KM) in the Digital Age

    OpenAIRE

    Thornley, Clare; Carcary, Marian; Connolly, Niall; O'Duffy, Michael; Pierce, John

    2016-01-01

    This paper arises from a work-in-progress academia/industry collaborative research project to develop a knowledge management (KM) maturity model as a component (critical capability) of the IT Capability Maturity Framework (IT-CMF). The aim of the project is to develop a knowledge management (KM) maturity model that is ‘fit for purpose’ for organisations in the digital age. In undertaking this work it became clear that, outside of the fundamental challenges of KM, new significant challenges an...

  12. 320 Gb/s Single polarization OTDM Transmission over 80 km Standard Transmission Fiber

    DEFF Research Database (Denmark)

    Siahlo, Andrei; Seoane, Jorge; Clausen, Anders

    2005-01-01

    Optical time-division multiplexing (OTDM) is an attractive technique for increasing the capacity of optical transmission systems. 320 Gbit/s single-channel and single-polarization error-free transmission over continuous spans of either 80 km SMF or 77 km NZDSF are realized.......Optical time-division multiplexing (OTDM) is an attractive technique for increasing the capacity of optical transmission systems. 320 Gbit/s single-channel and single-polarization error-free transmission over continuous spans of either 80 km SMF or 77 km NZDSF are realized....

  13. Protective effect of kombucha mushroom (KM) tea on phenol-induced cytotoxicity in albino mice.

    Science.gov (United States)

    Yapar, Kursad; Cavusoglu, Kultigin; Oruc, Ertan; Yalcin, Emine

    2010-09-01

    The present study was carried out to evaluate the protective role of kombucha mushroom (KM) tea on cytotoxicity induced by phenol (PHE) in mice. We used weight gain and micronucleus (MN) frequency as indicators of cytotoxicity and supported these parameters with pathological findings. The animals were randomly divided into seven groups: (Group I) only tap water (Group II) 1000 microl kg(-1) b. wt KM-tea, (Group III) 35 mg kg(-1) body wt. PHE (Group IV) 35 mg kg(-1) body wt. PHE + 250 microl kg(-1) b. wt KM-tea (Group V) 35 mg kg(-1) b. wt PHE + 500 microl kg(-1) b. wt KM-tea (Group VI) 35 mg kg(-1) b. wt PHE + 750 microl kg(-1) b. wt KM-tea, (Group VII) 35 mg kg(-1) b. wt PHE + 1000 microl kg(-1) b. wt KM-tea, for 20 consecutive days by oral gavage. The results indicated that all KM-tea supplemented mice showed a lower MN frequency than erythrocytes in only PHE-treated group. There was an observable regression on account of lesions in tissues of mice supplemented with different doses of KM-tea in histopathological observations. In conclusion, the KM-tea supplementation decreases cytotoxicity induced by PHE and its protective role is dose-dependent.

  14. Experimental Demonstration of 32 Gbaud 4-PAM for Data Center Interconnections of up to 320 km

    DEFF Research Database (Denmark)

    Madsen, Peter; Suhr, Lau Frejstrup; Clausen, Anders

    2017-01-01

    This paper presents experimental results demonstrating a 64 Gbps 4-PAM transmission over a 320 km SSMF span employing standard 80 km fiber spans for metro links. The receiver consists of a LPF and a DFE utilizing the DD-LMS algorithm.......This paper presents experimental results demonstrating a 64 Gbps 4-PAM transmission over a 320 km SSMF span employing standard 80 km fiber spans for metro links. The receiver consists of a LPF and a DFE utilizing the DD-LMS algorithm....

  15. Early changes of the anemia phenomenon in male 100-km ultramarathoners

    Directory of Open Access Journals (Sweden)

    Yu-Hui Chiu

    2015-02-01

    Conclusion: Running a 100-km ultramarathon will induce substantial sports anemia, and oxidative stress response, hemolysis, hematuria, and gastrointestinal bleeding are typical factors that contribute to its onset.

  16. Evaluation of NLDAS 12-km and downscaled 1-km temperature products in New York State for potential use in health exposure response studies

    Science.gov (United States)

    Estes, M. G., Jr.; Insaf, T.; Crosson, W. L.; Al-Hamdan, M. Z.

    2017-12-01

    Heat exposure metrics (maximum and minimum daily temperatures,) have a close relationship with human health. While meteorological station data provide a good source of point measurements, temporal and spatially consistent temperature data are needed for health studies. Reanalysis data such as the North American Land Data Assimilation System's (NLDAS) 12-km gridded product are an effort to resolve spatio-temporal environmental data issues; the resolution may be too coarse to accurately capture the effects of elevation, mixed land/water areas, and urbanization. As part of this NASA Applied Sciences Program funded project, the NLDAS 12-km air temperature product has been downscaled to 1-km using MODIS Land Surface Temperature patterns. Limited validation of the native 12-km NLDAS reanalysis data has been undertaken. Our objective is to evaluate the accuracy of both the 12-km and 1-km downscaled products using the US Historical Climatology Network station data geographically dispersed across New York State. Statistical methods including correlation, scatterplots, time series and summary statistics were used to determine the accuracy of the remotely-sensed maximum and minimum temperature products. The specific effects of elevation and slope on remotely-sensed temperature product accuracy were determined with 10-m digital elevation data that were used to calculate percent slope and link with the temperature products at multiple scales. Preliminary results indicate the downscaled temperature product improves accuracy over the native 12-km temperature product with average correlation improvements from 0.81 to 0.85 for minimum and 0.71 to 0.79 for maximum temperatures in 2009. However, the benefits vary temporally and geographically. Our results will inform health studies using remotely-sensed temperature products to determine health risk from excessive heat by providing a more robust assessment of the accuracy of the 12-km NLDAS product and additional accuracy gained from

  17. H0, q0 and the local velocity field. [Hubble and deceleration constants in Big Bang expansion

    Science.gov (United States)

    Sandage, A.; Tammann, G. A.

    1982-01-01

    An attempt is made to find a systematic deviation from linearity for distances that are under the control of the Virgo cluster, and to determine the value of the mean random motion about the systematic flow, in order to improve the measurement of the Hubble and the deceleration constants. The velocity-distance relation for large and intermediate distances is studied, and type I supernovae are calibrated relatively as distance indicators and absolutely to obtain a new value for the Hubble constant. Methods of determining the deceleration constant are assessed, including determination from direct measurement, mean luminosity density, virgocentric motion, and the time scale test. The very local velocity field is investigated, and a solution is preferred with a random peculiar radial velocity of very nearby field galaxies of 90-100 km/s, and a Virgocentric motion of the local group of 220 km/s, leading to an underlying expansion rate of 55, in satisfactory agreement with the global value.

  18. Constant force extensional rheometry of polymer solutions

    DEFF Research Database (Denmark)

    Szabo, Peter; McKinley, Gareth H.; Clasen, Christian

    2012-01-01

    We revisit the rapid stretching of a liquid filament under the action of a constant imposed tensile force, a problem which was first considered by Matta and Tytus [J. Non-Newton. Fluid Mech. 35 (1990) 215–229]. A liquid bridge formed from a viscous Newtonian fluid or from a dilute polymer solution...... is first established between two cylindrical disks. The upper disk is held fixed and may be connected to a force transducer while the lower cylinder falls due to gravity. By varying the mass of the falling cylinder and measuring its resulting acceleration, the viscoelastic nature of the elongating fluid...... filament can be probed. In particular, we show that with this constant force pull (CFP) technique it is possible to readily impose very large material strains and strain rates so that the maximum extensibility of the polymer molecules may be quantified. This unique characteristic of the experiment...

  19. f(R) constant-roll inflation

    Energy Technology Data Exchange (ETDEWEB)

    Motohashi, Hayato [Universidad de Valencia-CSIC, Instituto de Fisica Corpuscular (IFIC), Valencia (Spain); Starobinsky, Alexei A. [L.D. Landau Institute for Theoretical Physics, RAS, Moscow (Russian Federation); National Research University Higher School of Economics, Moscow (Russian Federation)

    2017-08-15

    The previously introduced class of two-parametric phenomenological inflationary models in general relativity in which the slow-roll assumption is replaced by the more general, constant-roll condition is generalized to the case of f(R) gravity. A simple constant-roll condition is defined in the original Jordan frame, and exact expressions for a scalaron potential in the Einstein frame, for a function f(R) (in the parametric form) and for inflationary dynamics are obtained. The region of the model parameters permitted by the latest observational constraints on the scalar spectral index and the tensor-to-scalar ratio of primordial metric perturbations generated during inflation is determined. (orig.)

  20. Benjamin Constant. Libertad, democracia y pluralismo

    Directory of Open Access Journals (Sweden)

    Claudia Patricia Fonnegra Osorio

    2015-12-01

    Full Text Available A partir de un enfoque interpretativo, en este artículo se aborda por qué para Benjamin Constant la democracia solo puede darse en donde se presenta una relación necesaria entre la libertad entendida como defensa de los derechos individuales -libertad como independencia o negativa- y la libertad concebida como principio de la participación pública -libertad como autonomía o positiva-. Asimismo, se presenta la importancia que atribuye el autor a las tradiciones que dan vida a la configuración del universo cultural de un pueblo. Se concluye que en la obra de Constant se encuentra una clara defensa del Estado de derecho y del pluralismo, la cual puede iluminar la comprensión de los problemas políticos de la contemporaneidad.

  1. Varying constants, black holes, and quantum gravity

    International Nuclear Information System (INIS)

    Carlip, S.

    2003-01-01

    Tentative observations and theoretical considerations have recently led to renewed interest in models of fundamental physics in which certain 'constants' vary in time. Assuming fixed black hole mass and the standard form of the Bekenstein-Hawking entropy, Davies, Davis and Lineweaver have argued that the laws of black hole thermodynamics disfavor models in which the fundamental electric charge e changes. I show that with these assumptions, similar considerations severely constrain 'varying speed of light' models, unless we are prepared to abandon cherished assumptions about quantum gravity. Relaxation of these assumptions permits sensible theories of quantum gravity with ''varying constants,'' but also eliminates the thermodynamic constraints, though the black hole mass spectrum may still provide some restrictions on the range of allowable models

  2. Cosmological constant in the quantum multiverse

    International Nuclear Information System (INIS)

    Larsen, Grant; Nomura, Yasunori; Roberts, Hannes L. L.

    2011-01-01

    Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. In this paper, we elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein.

  3. On determining dose rate constants spectroscopically

    International Nuclear Information System (INIS)

    Rodriguez, M.; Rogers, D. W. O.

    2013-01-01

    Purpose: To investigate several aspects of the Chen and Nath spectroscopic method of determining the dose rate constants of 125 I and 103 Pd seeds [Z. Chen and R. Nath, Phys. Med. Biol. 55, 6089–6104 (2010)] including the accuracy of using a line or dual-point source approximation as done in their method, and the accuracy of ignoring the effects of the scattered photons in the spectra. Additionally, the authors investigate the accuracy of the literature's many different spectra for bare, i.e., unencapsulated 125 I and 103 Pd sources. Methods: Spectra generated by 14 125 I and 6 103 Pd seeds were calculated in vacuo at 10 cm from the source in a 2.7 × 2.7 × 0.05 cm 3 voxel using the EGSnrc BrachyDose Monte Carlo code. Calculated spectra used the initial photon spectra recommended by AAPM's TG-43U1 and NCRP (National Council of Radiation Protection and Measurements) Report 58 for the 125 I seeds, or TG-43U1 and NNDC(2000) (National Nuclear Data Center, 2000) for 103 Pd seeds. The emitted spectra were treated as coming from a line or dual-point source in a Monte Carlo simulation to calculate the dose rate constant. The TG-43U1 definition of the dose rate constant was used. These calculations were performed using the full spectrum including scattered photons or using only the main peaks in the spectrum as done experimentally. Statistical uncertainties on the air kerma/history and the dose rate/history were ⩽0.2%. The dose rate constants were also calculated using Monte Carlo simulations of the full seed model. Results: The ratio of the intensity of the 31 keV line relative to that of the main peak in 125 I spectra is, on average, 6.8% higher when calculated with the NCRP Report 58 initial spectrum vs that calculated with TG-43U1 initial spectrum. The 103 Pd spectra exhibit an average 6.2% decrease in the 22.9 keV line relative to the main peak when calculated with the TG-43U1 rather than the NNDC(2000) initial spectrum. The measured values from three different

  4. Some Dynamical Effects of the Cosmological Constant

    Science.gov (United States)

    Axenides, M.; Floratos, E. G.; Perivolaropoulos, L.

    Newton's law gets modified in the presence of a cosmological constant by a small repulsive term (antigravity) that is proportional to the distance. Assuming a value of the cosmological constant consistent with the recent SnIa data (Λ~=10-52 m-2), we investigate the significance of this term on various astrophysical scales. We find that on galactic scales or smaller (less than a few tens of kpc), the dynamical effects of the vacuum energy are negligible by several orders of magnitude. On scales of 1 Mpc or larger however we find that the vacuum energy can significantly affect the dynamics. For example we show that the velocity data in the local group of galaxies correspond to galactic masses increased by 35% in the presence of vacuum energy. The effect is even more important on larger low density systems like clusters of galaxies or superclusters.

  5. Daylight calculations using constant luminance curves

    Energy Technology Data Exchange (ETDEWEB)

    Betman, E. [CRICYT, Mendoza (Argentina). Laboratorio de Ambiente Humano y Vivienda

    2005-02-01

    This paper presents a simple method to manually estimate daylight availability and to make daylight calculations using constant luminance curves calculated with local illuminance and irradiance data and the all-weather model for sky luminance distribution developed in the Atmospheric Science Research Center of the University of New York (ARSC) by Richard Perez et al. Work with constant luminance curves has the advantage that daylight calculations include the problem's directionality and preserve the information of the luminous climate of the place. This permits accurate knowledge of the resource and a strong basis to establish conclusions concerning topics related to the energy efficiency and comfort in buildings. The characteristics of the proposed method are compared with the method that uses the daylight factor. (author)

  6. Understanding fine structure constants and three generations

    International Nuclear Information System (INIS)

    Bennett, D.L.; Nielsen, H.B.

    1988-02-01

    We put forward a model inspired by random dynamics that relates the smallness of the gauge coupling constants to the number of generations being 'large'. The new element in the present version of our model is the appearance of a free parameter χ that is a measure of the (presumably relatively minor) importance of a term in the plaquette action proportional to the trace in the (1/6, 2, 3) representation of the Standard Model. Calling N gen the number of generations, the sets of allowed (N gen , χN gen )-pairs obtained by imposing the three measured coupling constant values of the Standard Model form three lines. In addition to finding that these lines cross at a single point (as needed for a consistent fit), the intersection occurs with surprising accuracy at the integer N gen = 3 (thereby predicting exactly three generations). It is also encouraging that the parameter χ turns out to be small and positive as expected. (orig.)

  7. Bardeen-Cooper-Schrieffer universal constants generalized

    International Nuclear Information System (INIS)

    Hazaimeh, A.H.

    1992-01-01

    Weak- and moderate-coupling BCS superconductivity theory is shown to admit a more general T c formula, wherein T c approaches zero somewhat faster than with the familiar BCS T c -formula. This theory leads to a departure from the universal behavior of the gap-to-T c ratio and is consistent with some recent empirical values for exotic superconductors. This ratio is smaller than the universal BCS value of 3.53 in a way which is consistent with weak electron-boson coupling. Similarly, other universal constants related to specific heat and critical magnetic field are modified. In this dissertation, The author investigates the latter constants for weak-coupling and moderate-coupling and carry out detailed comparisons with experimental data for the cuprates and with the corresponding predictions of strong-coupling theory. This effort is to elucidate the nature of these superconductors with regards to coupling strength within an electron-boson mechanism

  8. Multiphoton amplitude in a constant background field

    Science.gov (United States)

    Ahmad, Aftab; Ahmadiniaz, Naser; Corradini, Olindo; Kim, Sang Pyo; Schubert, Christian

    2018-01-01

    In this contribution, we present our recent compact master formulas for the multiphoton amplitudes of a scalar propagator in a constant background field using the worldline fomulation of quantum field theory. The constant field has been included nonperturbatively, which is crucial for strong external fields. A possible application is the scattering of photons by electrons in a strong magnetic field, a process that has been a subject of great interest since the discovery of astrophysical objects like radio pulsars, which provide evidence that magnetic fields of the order of 1012G are present in nature. The presence of a strong external field leads to a strong deviation from the classical scattering amplitudes. We explicitly work out the Compton scattering amplitude in a magnetic field, which is a process of potential relevance for astrophysics. Our final result is compact and suitable for numerical integration.

  9. Piezooptical constants of Rochelle salt crystals

    OpenAIRE

    V.Yo. Stadnyk; M.O. Romanyuk; V.Yu. Kurlyak; V.F.Vachulovych

    2000-01-01

    The influence of uniaxial mechanical pressure applied along the principal axes and the corresponding bisectors on the birefringent properties of Rochelle salt (RS) crystals are studied. The temperature (77-300 K) and spectral (300-700 nm) dependencies of the effective and absolute piezooptical constants of the RS crystals are calculated. The intercept of dispersion curves of is revealed in the region of the birefringence sign inversion. This testifies that the anizotropy of the piezooptical ...

  10. Simulated annealing with constant thermodynamic speed

    International Nuclear Information System (INIS)

    Salamon, P.; Ruppeiner, G.; Liao, L.; Pedersen, J.

    1987-01-01

    Arguments are presented to the effect that the optimal annealing schedule for simulated annealing proceeds with constant thermodynamic speed, i.e., with dT/dt = -(v T)/(ε-√C), where T is the temperature, ε- is the relaxation time, C ist the heat capacity, t is the time, and v is the thermodynamic speed. Experimental results consistent with this conjecture are presented from simulated annealing on graph partitioning problems. (orig.)

  11. A noteworthy dimensionless constant in gravitation theory

    International Nuclear Information System (INIS)

    Fayos, F.; Lobo, J.A.; Llanta, E.

    1986-01-01

    A simple problem of gravitation is studied classically and in the Schwarzchild framework. A relationship is found between the parameters that define the trajectories of two particles (the first in radial motion and the second in a circular orbit) which are initially together and meet again after one revolution of particle 2. Dimensional analysis is the clue to explain the appearance of a dimensionless constant in the Newtonian case. (author)

  12. Electromagnetic corrections to pseudoscalar decay constants

    Energy Technology Data Exchange (ETDEWEB)

    Glaessle, Benjamin Simon

    2017-03-06

    First principles Lattice quantum chromodynamics (LQCD) calculations enable the determination of low energy hadronic amplitudes. Precision LQCD calculations with relative errors smaller than approximately 1% require the inclusion of electromagnetic effects. We demonstrate that including (quenched) quantum electrodynamics effects in the LQCD calculation effects the values obtained for pseudoscalar decay constants in the per mille range. The importance of systematic effects, including finite volume effects and the charge dependence of renormalization and improvement coefficients, is highlighted.

  13. Cosmological Constant and the Final Anthropic Hypothesis

    OpenAIRE

    Cirkovic, Milan M.; Bostrom, Nick

    1999-01-01

    The influence of recent detections of a finite vacuum energy ("cosmological constant") on our formulation of anthropic conjectures, particularly the so-called Final Anthropic Principle is investigated. It is shown that non-zero vacuum energy implies the onset of a quasi-exponential expansion of our causally connected domain ("the universe") at some point in the future, a stage similar to the inflationary expansion at the very beginning of time. The transition to this future inflationary phase...

  14. Singlet axial constant from QCD sum rules

    International Nuclear Information System (INIS)

    Belitskij, A.V.; Teryaev, O.V.

    1995-01-01

    We analyze the singlet axial form factor of the proton for small momentum transferred in the framework of QCD sum rules using the interpolating nucleon current which explicitly accounts for the gluonic degrees of freedom. As the result we come to the quantitative prediction of the singlet axial constant. It is shown that the bilocal power corrections play the most important role in the analysis. 21 refs., 3 figs

  15. Lattice Paths and the Constant Term

    International Nuclear Information System (INIS)

    Brak, R; Essam, J; Osborn, J; Owczarek, A L; Rechnitzer, A

    2006-01-01

    We firstly review the constant term method (CTM), illustrating its combinatorial connections and show how it can be used to solve a certain class of lattice path problems. We show the connection between the CTM, the transfer matrix method (eigenvectors and eigenvalues), partial difference equations, the Bethe Ansatz and orthogonal polynomials. Secondly, we solve a lattice path problem first posed in 1971. The model stated in 1971 was only solved for a special case - we solve the full model

  16. Elastic constants from microscopic strain fluctuations

    Science.gov (United States)

    Sengupta; Nielaba; Rao; Binder

    2000-02-01

    Fluctuations of the instantaneous local Lagrangian strain epsilon(ij)(r,t), measured with respect to a static "reference" lattice, are used to obtain accurate estimates of the elastic constants of model solids from atomistic computer simulations. The measured strains are systematically coarse-grained by averaging them within subsystems (of size L(b)) of a system (of total size L) in the canonical ensemble. Using a simple finite size scaling theory we predict the behavior of the fluctuations as a function of L(b)/L and extract elastic constants of the system in the thermodynamic limit at nonzero temperature. Our method is simple to implement, efficient, and general enough to be able to handle a wide class of model systems, including those with singular potentials without any essential modification. We illustrate the technique by computing isothermal elastic constants of "hard" and "soft" disk triangular solids in two dimensions from Monte Carlo and molecular dynamics simulations. We compare our results with those from earlier simulations and theory.

  17. Emergent gravity in spaces of constant curvature

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Orlando; Haddad, Matthew [Department of Physics, University of Miami,1320 Campo Sano Ave, Coral Gables, FL 33146 (United States)

    2017-03-07

    In physical theories where the energy (action) is localized near a submanifold of a constant curvature space, there is a universal expression for the energy (or the action). We derive a multipole expansion for the energy that has a finite number of terms, and depends on intrinsic geometric invariants of the submanifold and extrinsic invariants of the embedding of the submanifold. This is the second of a pair of articles in which we try to develop a theory of emergent gravity arising from the embedding of a submanifold into an ambient space equipped with a quantum field theory. Our theoretical method requires a generalization of a formula due to by Hermann Weyl. While the first paper discussed the framework in Euclidean (Minkowski) space, here we discuss how this framework generalizes to spaces of constant sectional curvature. We focus primarily on anti de Sitter space. We then discuss how such a theory can give rise to a cosmological constant and Planck mass that are within reasonable bounds of the experimental values.

  18. Planck Constant Determination from Power Equivalence

    Science.gov (United States)

    Newell, David B.

    2000-04-01

    Equating mechanical to electrical power links the kilogram, the meter, and the second to the practical realizations of the ohm and the volt derived from the quantum Hall and the Josephson effects, yielding an SI determination of the Planck constant. The NIST watt balance uses this power equivalence principle, and in 1998 measured the Planck constant with a combined relative standard uncertainty of 8.7 x 10-8, the most accurate determination to date. The next generation of the NIST watt balance is now being assembled. Modification to the experimental facilities have been made to reduce the uncertainty components from vibrations and electromagnetic interference. A vacuum chamber has been installed to reduce the uncertainty components associated with performing the experiment in air. Most of the apparatus is in place and diagnostic testing of the balance should begin this year. Once a combined relative standard uncertainty of one part in 10-8 has been reached, the power equivalence principle can be used to monitor the possible drift in the artifact mass standard, the kilogram, and provide an accurate alternative definition of mass in terms of fundamental constants. *Electricity Division, Electronics and Electrical Engineering Laboratory, Technology Administration, U.S. Department of Commerce. Contribution of the National Institute of Standards and Technology, not subject to copyright in the U.S.

  19. Constant leverage and constant cost of capital : A common knowledge half-truth

    OpenAIRE

    Vélez Pareja, Ignacio; Ibragimov, Rauf; Tham , Joseph

    2008-01-01

    Un enfoque típico para valorar flujos de caja finitos es suponer que el endeudamiento es constante (generalmente como un endeudamiento objetivo o deseado) y que por tanto, el costo del patrimonio, Ke y el costo promedio ponderado de capital CPPC, también son constantes. Para los flujos de caja perpetuos, y con el costo de la deuda, Kd como la tasa de descuento para el ahorro en impuestos o escudo fiscal, Ke y el CPPC aplicado al flujo de caja libre FCL son constantes si el endeudamiento es co...

  20. An independent determination of the local Hubble constant

    Science.gov (United States)

    Fernández Arenas, David; Terlevich, Elena; Terlevich, Roberto; Melnick, Jorge; Chávez, Ricardo; Bresolin, Fabio; Telles, Eduardo; Plionis, Manolis; Basilakos, Spyros

    2018-02-01

    The relationship between the integrated H β line luminosity and the velocity dispersion of the ionized gas of H II galaxies and giant H II regions represents an exciting standard candle that presently can be used up to redshifts z ˜ 4. Locally it is used to obtain precise measurements of the Hubble constant by combining the slope of the relation obtained from nearby (z ≤ 0.2) H II galaxies with the zero-point determined from giant H II regions belonging to an `anchor sample' of galaxies for which accurate redshift-independent distance moduli are available. We present new data for 36 giant H II regions in 13 galaxies of the anchor sample that includes the megamaser galaxy NGC 4258. Our data are the result of the first 4 yr of observation of our primary sample of 130 giant H II regions in 73 galaxies with Cepheid determined distances. Our best estimate of the Hubble parameter is 71.0 ± 2.8(random) ± 2.1(systematic) km s- 1Mpc- 1. This result is the product of an independent approach and, although at present less precise than the latest SNIa results, it is amenable to substantial improvement.

  1. The Far-Field Hubble Constant

    Science.gov (United States)

    Lauer, Tod

    1995-07-01

    We request deep, near-IR (F814W) WFPC2 images of five nearby Brightest Cluster Galaxies (BCG) to calibrate the BCG Hubble diagram by the Surface Brightness Fluctuation (SBF) method. Lauer & Postman (1992) show that the BCG Hubble diagram measured out to 15,000 km s^-1 is highly linear. Calibration of the Hubble diagram zeropoint by SBF will thus yield an accurate far-field measure of H_0 based on the entire volume within 15,000 km s^-1, thus circumventing any strong biases caused by local peculiar velocity fields. This method of reaching the far field is contrasted with those using distance ratios between Virgo and Coma, or any other limited sample of clusters. HST is required as the ground-based SBF method is limited to team developed the SBF method, the first BCG Hubble diagram based on a full-sky, volume-limited BCG sample, played major roles in the calibration of WFPC and WFPC2, and are conducting observations of local galaxies that will validate the SBF zeropoint (through GTO programs). This work uses the SBF method to tie both the Cepheid and Local Group giant-branch distances generated by HST to the large scale Hubble flow, which is most accurately traced by BCGs.

  2. Quality control considerations for the KM3NeT Very Large Volume Neutrino Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Sollima, C., E-mail: c.sollima@ing.unipi.it

    2013-10-11

    Within the KM3NeT project a quality management system was proposed that included a qualification process and a database to store information on the design. This paper highlights quality control procedures applicable to KM3NeT and describes the database.

  3. GHRSST Level 4 Australian Bureau of Meteorology GAMSSA_28km Global SST:1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GAMSSA v1.0 system blends NAVOCEANO's GAC 9.9 km x 4.4 km resolution AVHRR L2P SST1m data (NOAA-17, NOAA-18 and METOP-A), European Space Agency's 0.17 AATSR skin...

  4. Resting sympatho-vagal balance is related to 10 km running performance in master endurance athletes

    Directory of Open Access Journals (Sweden)

    Angelo Cataldo

    2018-02-01

    Full Text Available Relationships between heart rate recovery after exercise (HRR, baseline heart rate variability measures (HRV, and time to perform a 10Km running trial (t10Km were evaluated in "master" athletes of endurance to assess whether the measured indexes may be useful for monitoring the training status of the athletes. Ten “master” athletes of endurance, aged 40-60 years, were recruited. After baseline measures of HRV, the athletes performed a graded maximal test on treadmill and HRR was measured at 1 and 2 minutes from recovery. Subsequently they performed a 10Km running trial and t10Km was related to HRV and HRR indexes. The time to perform a 10Km running trial was significantly correlated with baseline HRV indexes. No correlation was found between t10Km and HRR. Baseline HRV measures, but not HRR, were significantly correlated with the time of performance on 10km running in “master” athletes. The enhanced parasympathetic function at rest appears to be a condition to a better performance on 10km running. HRV can be simple and useful measurements for monitoring the training stratus of athletes and their physical condition in proximity of a competition.

  5. MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km (MOD021KM) contains calibrated and geolocated at-aperture radiances for 36 discrete bands located in the 0.4...

  6. The landscape basis of the complex monitoring of 30-km zone of NPP

    International Nuclear Information System (INIS)

    Malisheva, L.L.; Romanchuk, S.P.; Schur, U.V.; Rybalko, S.I.; Proskura, N.I.; Lury, D.I.

    1992-01-01

    This publication reviews works on the problem of creation the landscape basis of complex monitoring in 30 km zone of NPP(nuclear power plants). The objectives, subject and designation of monitoring system are considered. The monitoring network and organization of systematical observations are justified. The structure of radiation monitoring in NPP 30 km zone is considered in details. (author)

  7. A Co-Creation Blended KM Model for Cultivating Critical-Thinking Skills

    Science.gov (United States)

    Yeh, Yu-chu

    2012-01-01

    Both critical thinking (CT) and knowledge management (KM) skills are necessary elements for a university student's success. Therefore, this study developed a co-creation blended KM model to cultivate university students' CT skills and to explore the underlying mechanisms for achieving success. Thirty-one university students participated in this…

  8. Ad-libitum drinking and performance during a 40-km cycling time trial in the heat

    NARCIS (Netherlands)

    Berkulo, M.A.R.; Bol, S.; Levels, K.; Lamberts, R.P.; Daanen, H.A.M.; Noakes, T.D.

    2015-01-01

    The aim of this study was to investigate if drinking ad-libitum can counteract potential negative effects of a hypohydrated start caused by fluid restriction during a 40-km time trial (TT) in the heat. Twelve trained males performed one 40-km cycling TT euhydrated (EU: no water during the TT) and

  9. Ad-libitum drinking and performance during a 40-km cycling time trial in the heat

    NARCIS (Netherlands)

    Berkulo, M.A.R.; Bol, S.; Levels, K.; Lamberts, R.P.; Daanen, H.A.M.; Noakes, T.D.

    2016-01-01

    The aim of this study was to investigate if drinking ad-libitum can counteract potential negative effects of a hypohydrated start caused by fluid restriction during a 40-km time trial (TT) in the heat. Twelve trained males performed one 40-km cycling TT euhydrated (EU: no water during the TT) and

  10. Assessment of the 2,4 km run as a predictor of aerobic capacity ...

    African Journals Online (AJOL)

    Since the 2,4 km run time test is routinely used in military training programmes as an indicator of aerobic capacity and its possible improvement, an attempt was made to: (i) establish a regression equation of V02max V. 2,4 km run time in a group of 20 young military volunteers; and (ii) determine whether this equation could ...

  11. MODIS/Terra Calibrated Radiances 5-Min L1B Swath 1km Subsetted V005

    Data.gov (United States)

    National Aeronautics and Space Administration — This data type (MOD02SSH) is a subsample from the MODIS Level 1B 1-km data. Every fifth pixel is taken from the MOD021KM product and written out to MOD02SSH. The...

  12. Towards an integrated methodology to develop KM solutions with the support of agents

    NARCIS (Netherlands)

    Guizzardi-Silva Souza, R.; Dignum, V.; Perini, A.; Wagner, G.; Thompson, C.; Hexmoor, H.

    Activities related to Knowledge Management (KM) processes require changes within the organizational processes in order to accommodate new goals and tasks, besides changing the way people view and do their work. In this paper, we argue that agents are suitable for modeling KM contexts, due to their

  13. Design and mass production of the optical modules for KM3NeT-Italia project

    Directory of Open Access Journals (Sweden)

    Leonora Emanuele

    2016-01-01

    Full Text Available The KM3NeT European project aims at constructing a km3 underwater neutrino telescope in the depths of the Mediterranean Sea. The first phase that is under construction will comprise eight tower-like detection structures (KM3NeT-Italia, which will form the internal core of a km3-scale detector. The detection element of KM3NeT-Italia, the optical module, is made of a 13-inch pressure-resistant glass-vessel that contains a single 10-inch photomultiplier and the relative electronics. The design of the whole optical module, the main results obtained from the massive photomultipliers measurements, and the foremost phases of the mass production procedure performed at the production site of Catania are also presented.

  14. Pure Rotational Raman Lidar for Temperature Measurements from 5-40 Km Over Wuhan, China

    Directory of Open Access Journals (Sweden)

    Li Yajuan

    2016-01-01

    Full Text Available In this paper a pure rotational Raman lidar (PRR was established for the atmospheric temperature measurements from 5 km to 40 km over Wuhan, China (30.5°N, 114.5°E. To extract the expected PRR signals and simultaneously suppress the elastically backscattered light, a high-spectral resolution polychromator for light splitting and filtering was designed. Observational results revealed that the temperature difference measured by PRR lidar and the local radiosonde below 30 km was less than 3.0 K. The good agreement validated the reliability of the PRR lidar. With the 1-h integration and 150-m spatial resolution, the statistical temperature error for PRR lidar increases from 0.4 K at 10 km up to 4 K at altitudes of about 30 km. In addition, the whole night temperature profiles were obtained for study of the long-term observation of atmospheric fluctuations.

  15. Determination of protonation constants of hydroquinone and stability constants of Th(IV) hydroquinone complex

    International Nuclear Information System (INIS)

    Sawant, R.M.; Ramakumar, K.L.; Sharma, R.S.

    2003-01-01

    Protonation constants of hydroquinone and stability constants of thorium hydroquinone complexes were determined in 1 M NaClO 4 medium at 25 ± 0.5 degC, by varying concentration of thorium, using pH titration technique. Protonation constants of hydroquinone (β 1H = [HQ]/[H][Q] and β 2H = [H 2 Q]/[H] 2 [Q]) were found to be β 1H = 11.404 ± 0.014 and β 2H = 21.402 ± 0.012. The analysis of titration data of thorium-hydroquinone system appears to indicate the formation of species Th(H 2 Q) 3 (OH) and Th(H 2 O) 4 (OH). Equilibrium constants obtained for these species are -log β 13-I = 48.51 ± 0.67 and -log β 14-1 64.86 ± 1.25 respectively which are not reported in the literature. (author)

  16. Dispersion studies with continuous release near Petten, 3.5 km from the shore

    International Nuclear Information System (INIS)

    Westhoff, J.W.; Dam, G.C. van; Davids, J.A.G.

    1971-01-01

    An experiment is described in which the spread of a continuously injected tracer, rhodamine-B, was studied as a function of time and place. The tracer was released over a period of 12 days at a constant rate with the implementation of an existing pipeline which debouches into the sea at a distance of 3.5 km from the Netherlands' coast near Petten. The main experiment was performed in the fall of 1966; a preparative experiment on a smaller scale was made in 1965. The investigation as a whole has three purposes: a) acquisition of an immediate and direct insight into the pattern of spreading arising with continuous release of conservative, dissolvable materials at the Petten disposal site; b) the obtaining of parametric values to be used in mathematical models by which situations other than the one observed can be computed (e.g. release of non-conservative substances, longer release periods, periods with different net current values etc.); c) an increase in the understanding of diffusion and advection processes in the sea, as well as pertinent information concerning currents and turbulence patterns. In broadening this understanding, mathematical models play the part of an auxiliary tool. Comparison with results from other times and places is important. The knowledge gained may lead, among other things, to an extension of the set of models or to modifications within the existing models and in this way achieve a certain degree of feedback for various practical applications. For direct application the report at hand can only be used for purpose a). The remaining two purposes require a further examination of the material, for which the reader is referred to the proposed supplementary report (ref. 8). The principal expedients used for the observations in the present experiments have been fluorimetric determination of tracer concentration (by means of both surf zone samples and continuous sampling with direct detection and recording aboard cruising ships) and aerial

  17. Effects of training and anthropometric factors on marathon and 100 km ultramarathon race performance

    Directory of Open Access Journals (Sweden)

    Tanda G

    2015-04-01

    Full Text Available Giovanni Tanda,1 Beat Knechtle2,3 1Polytechnic School, University of Genoa, Genoa, Italy; 2Gesundheitszentrum St Gallen, St Gallen, 3Institute of Primary Care, University of Zurich, Zurich, Switzerland Background: Marathon (42 km and 100 km ultramarathon races are increasing in popularity. The aim of the present study was to investigate the potential associations of anthropometric and training variables with performance in these long-distance running competitions. Methods: Training and anthropometric data from a large cohort of marathoners and 100 km ultramarathoners provided the basis of this work. Correlations between training and anthropometric indices of subjects and race performance were assessed using bivariate and multiple regression analyses. Results: A combination of volume and intensity in training was found to be suitable for prediction of marathon and 100 km ultramarathon race pace. The relative role played by these two variables was different, in that training volume was more important than training pace for the prediction of 100 km ultramarathon performance, while the opposite was found for marathon performance. Anthropometric characteristics in terms of body fat percentage negatively affected 42 km and 100 km race performance. However, when this factor was relatively low (ie, less than 15% body fat, the performance of 42 km and 100 km races could be predicted solely on the basis of training indices. Conclusion: Mean weekly training distance run and mean training pace were key predictor variables for both marathon and 100 km ultramarathon race performance. Predictive correlations for race performance are provided for runners with a relatively low body fat percentage. Keywords: running, performance, training indices, body fat, sports training

  18. Constant load and constant displacement stress corrosion in simulated water reactor environments

    International Nuclear Information System (INIS)

    Lloyd, G.J.

    1987-02-01

    The stress corrosion behaviour of selected water reactor constructional materials, as determined by constant load or constant displacement test techniques, is reviewed. Experimental results obtained using a very wide range of conditions have been collected in a form for easy reference. A discussion is given of some apparent trends in these data. The possible reasons for these trends are considered together with a discussion of how the observed discrepancies may be resolved. (author)

  19. CONSTANT LEVERAGE AND CONSTANT COST OF CAPITAL: A COMMON KNOWLEDGE HALF-TRUTH

    Directory of Open Access Journals (Sweden)

    IGNACIO VÉLEZ-PAREJA

    2008-01-01

    Full Text Available Un enfoque típico para valorar flujos de caja finitos es suponer que el endeudamiento es constante (generalmente como un endeudamiento objetivo o deseado y que por tanto, el costo del patrimonio, Ke y el costo promedio ponderado de capital CPPC, también son constantes. Para los flujos de caja perpetuos, y con el costo de la deuda, Kd como la tasa de descuento para el ahorro en impuestos o escudo fiscal, Ke y el CPPC aplicado al flujo de caja libre FCL son constantes si el endeudamiento es constante. Sin embargo esto no es verdad para los flujos de caja finitos. En este documento mostramos que para flujos de caja finitos, Ke y por lo tanto el CPPC dependen de la tasa de descuento que se utiliza para valorar el ahorro en impuestos, AI y según lo esperado, Ke y el CPPC no son constantes con Kd como la tasa de descuento para el ahorro en impuestos, aunque el endeudamiento sea constante. Ilustramos esta situación con un ejemplo simple. Analizamos cinco métodos: el flujo de caja descontado, FCD, usando APV, el FCD y la formulación tradicional y general del CPPC, el valor presente del flujo de caja del accionista, FCA más deuda y el flujo de caja de capital, FCC.

  20. Inflation with a smooth constant-roll to constant-roll era transition

    Science.gov (United States)

    Odintsov, S. D.; Oikonomou, V. K.

    2017-07-01

    In this paper, we study canonical scalar field models, with a varying second slow-roll parameter, that allow transitions between constant-roll eras. In the models with two constant-roll eras, it is possible to avoid fine-tunings in the initial conditions of the scalar field. We mainly focus on the stability of the resulting solutions, and we also investigate if these solutions are attractors of the cosmological system. We shall calculate the resulting scalar potential and, by using a numerical approach, we examine the stability and attractor properties of the solutions. As we show, the first constant-roll era is dynamically unstable towards linear perturbations, and the cosmological system is driven by the attractor solution to the final constant-roll era. As we demonstrate, it is possible to have a nearly scale-invariant power spectrum of primordial curvature perturbations in some cases; however, this is strongly model dependent and depends on the rate of the final constant-roll era. Finally, we present, in brief, the essential features of a model that allows oscillations between constant-roll eras.

  1. Allocating emissions to 4 km and 1 km horizontal spatial resolutions and its impact on simulated NOx and O3 in Houston, TX

    Science.gov (United States)

    Pan, Shuai; Choi, Yunsoo; Roy, Anirban; Jeon, Wonbae

    2017-09-01

    A WRF-SMOKE-CMAQ air quality modeling system was used to investigate the impact of horizontal spatial resolution on simulated nitrogen oxides (NOx) and ozone (O3) in the Greater Houston area (a non-attainment area for O3). We employed an approach recommended by the United States Environmental Protection Agency to allocate county-based emissions to model grid cells in 1 km and 4 km horizontal grid resolutions. The CMAQ Integrated Process Rate analyses showed a substantial difference in emissions contributions between 1 and 4 km grids but similar NOx and O3 concentrations over urban and industrial locations. For example, the peak NOx emissions at an industrial and urban site differed by a factor of 20 for the 1 km and 8 for the 4 km grid, but simulated NOx concentrations changed only by a factor of 1.2 in both cases. Hence, due to the interplay of the atmospheric processes, we cannot expect a similar level of reduction of the gas-phase air pollutants as the reduction of emissions. Both simulations reproduced the variability of NASA P-3B aircraft measurements of NOy and O3 in the lower atmosphere (from 90 m to 4.5 km). Both simulations provided similar reasonable predictions at surface, while 1 km case depicted more detailed features of emissions and concentrations in heavily polluted areas, such as highways, airports, and industrial regions, which are useful in understanding the major causes of O3 pollution in such regions, and to quantify transport of O3 to populated communities in urban areas. The Integrated Reaction Rate analyses indicated a distinctive difference of chemistry processes between the model surface layer and upper layers, implying that correcting the meteorological conditions at the surface may not help to enhance the O3 predictions. The model-observation O3 bias in our studies (e.g., large over-prediction during the nighttime or along Gulf of Mexico coastline), were due to uncertainties in meteorology, chemistry or other processes. Horizontal grid

  2. Global Investigation of the Mg Atom and ion Layers using SCIAMACHY/Envisat Observations between 70 km and 150 km Altitude and WACCM-MG Model Results

    Science.gov (United States)

    Langowski, M.; vonSavigny, C.; Burrows, J. P.; Feng, W.; Plane, J. M. C.; Marsh, D. R.; Janches, Diego; Sinnhuber, M.; Aikin, A. C.

    2014-01-01

    Mg and Mg+ concentration fields in the upper mesosphere/lower thermosphere (UMLT) region are retrieved from SCIAMACHY/Envisat limb measurements of Mg and Mg+ dayglow emissions using a 2-D tomographic retrieval approach. The time series of monthly means of Mg and Mg+ for number density as well as vertical column density in different latitudinal regions are shown. Data from the limb mesosphere-thermosphere mode of SCIAMACHY/Envisat are used, which covers the 50 km to 150 km altitude region with a vertical sampling of 3.3 km and a highest latitude of 82 deg. The high latitudes are not covered in the winter months, because there is no dayglow emission during polar night. The measurements were performed every 14 days from mid-2008 until April 2012. Mg profiles show a peak at around 90 km altitude with a density between 750 cm(exp-3) and 2000 cm(exp-3). Mg does not show strong seasonal variation at mid-latitudes. The Mg+ peak occurs 5-15 km above the neutral Mg peak at 95-105 km. Furthermore, the ions show a significant seasonal cycle with a summer maximum in both hemispheres at mid- and high-latitudes. The strongest seasonal variations of the ions are observed at mid-latitudes between 20-40 deg and densities at the peak altitude range from 500 cm(exp-3) to 6000 cm(exp-3). The peak altitude of the ions shows a latitudinal dependence with a maximum at mid-latitudes that is up to 10 km higher than the peak altitude at the equator. The SCIAMACHY measurements are compared to other measurements and WACCM model results. In contrast to the SCIAMACHY results, the WACCM results show a strong seasonal variability for Mg with a winter maximum, which is not observable by SCIAMACHY, and globally higher peak densities. Although the peak densities do not agree the vertical column densities agree, since SCIAMACHY results show a wider vertical profile. The agreement of SCIAMACHY and WACCM results is much better for Mg+, showing the same seasonality and similar peak densities. However

  3. TASI Lectures on the cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Bousso, Raphael; Bousso, Raphael

    2007-08-30

    The energy density of the vacuum, Lambda, is at least 60 orders of magnitude smaller than several known contributions to it. Approaches to this problem are tightly constrained by data ranging from elementary observations to precision experiments. Absent overwhelming evidence to the contrary, dark energy can only be interpreted as vacuum energy, so the venerable assumption that Lambda=0 conflicts with observation. The possibility remains that Lambda is fundamentally variable, though constant over large spacetime regions. This can explain the observed value, but only in a theory satisfying a number of restrictive kinematic and dynamical conditions. String theory offers a concrete realization through its landscape of metastable vacua.

  4. Theoretical isochrones with decreasing gravitational constant

    International Nuclear Information System (INIS)

    Vandenberg, D.A.

    1976-01-01

    Van Flandern has postulated a variation of the gravitational constant at the rate approximately -8 x 10 -11 /yr. This variation, consistent with Hoyle-Narlikar and Dirac cosmologies, has been assumed in the computation of a 5 x 10 9 yr theoretical isochrone. Present results show that, even for this age, theory predicts a cluster turn-off luminosity approximately 0.5 to 1.0 mag fainter than the observed turn-offs of globular clusters. Unsatisfactory agreement between theoretical and observed luminosity functions is also indicated. (author)

  5. Quantum black holes and Planck's constant

    International Nuclear Information System (INIS)

    Ross, D.K.

    1987-01-01

    It is shown that the Planck-scale black holes of quantum gravity must obey a consistency condition relating Planck's constant to the integral of the mass of the black holes over time, if the usual path integral formulation of quantum mechanics is to make sense on physical spacetime. It is also shown, using time-dependent perturbation theory in ordinary quantum mechanics, that a massless particle will not propagate on physical spacetime with the black holes present unless the same condition is met. (author)

  6. Constant displacement rate testing at elevated temperatures

    International Nuclear Information System (INIS)

    Pepe, J.J.; Gonyea, D.C.

    1989-01-01

    A short time test has been developed which is capable of determining the long time notch sensitivity tendencies of CrMoV rotor forging materials. This test is based on Constant Displacement Rate (CDR) testing of a specific notch bar specimen at 1200 0 F at 2 mils/in/hour displacement rate. These data were correlated to conventional smooth and notch bar rupture behavior for a series of CrMoV materials with varying long time ductility tendencies. The purpose of this paper is to describe the details of this new test procedure and some of the relevant mechanics of material information generated during its development

  7. Radiation balances and the solar constant

    Science.gov (United States)

    Crommelynck, D.

    1981-01-01

    The radiometric concepts are defined in order to consider various types of radiation balances and relate them to the diabetic form of the energy balance. Variability in space and time of the components of the radiation field are presented. A specific concept for sweeping which is tailored to the requirements is proposed. Finally, after establishing the truncated character of the present knowledge of the radiation balance. The results of the last observations of the solar constant are given. Ground and satellite measurement techniques are discussed.

  8. O(4) texture with a cosmological constant

    International Nuclear Information System (INIS)

    Cho, Inyong

    2002-01-01

    We investigate O(4) textures in a background with a positive cosmological constant. We find static solutions which comove with the expanding background. There exists a solution in which the scalar field is regular at the horizon. This solution has a noninteger winding number smaller than 1. There also exist solutions in which scalar-field derivatives are singular at the horizon. Such solutions can complete one winding within the horizon. If the winding number is larger than some critical value, static solutions including the regular one are unstable under perturbations

  9. Can the cosmological constant undergo abrupt changes?

    CERN Document Server

    Cabo-Montes de Oca, Alejandro; Rosabal, A; Cabo, Alejandro; Garcia-Chung, Alejandro; Rosabal, Alejandro

    2005-01-01

    The existence of a simple spherically symmetric and static solution of the Einstein equations in the presence of a cosmological constant vanishing outside a definite value of the radial distance is investigated. A particular succession of field configurations, which are solutions of the Einstein equations in the presence of the considered cosmological term and auxiliary external sources, is constructed. Then, it is shown that the associated succession of external sources tend to zero in the sense of the generalized functions. The type of weak solution that is found becomes the deSitter homogeneous space-time for the interior region, and the Schwartzschild space in the outside zone.

  10. The Boltzmann constant from a snifter

    International Nuclear Information System (INIS)

    Tyukodi, B; Sárközi, Zs; Néda, Z; Tunyagi, A; Györke, E

    2012-01-01

    Evaporation of a small glass of ethylic alcohol is studied both experimentally and through an elementary thermal physics approach. For a cylindrical beaker and no air flow in the room, a simple quadratic relation is found between the evaporation time and the mass of evaporated liquid. This problem and the obtained results offer excellent possibilities for simple student experiments and for testing basic principles of thermal physics. As an example, we use the obtained results for estimating the value of the Boltzmann constant from evaporation experiments. (paper)

  11. Asymptotics with a positive cosmological constant II

    Science.gov (United States)

    Kesavan, Aruna; Ashtekar, Abhay; Bonga, Beatrice

    2015-04-01

    The study of isolated systems has been vastly successful in the context of vanishing cosmological constant, Λ = 0 . However, there is no physically useful notion of asymptotics for the universe we inhabit with Λ > 0 . This means that presently there is no fundamental understanding of gravitational waves in our own universe. The full non-linear framework is still under development, but some interesting results at the linearized level have been obtained. In particular, I will discuss the quadrupole formula for gravitational radiation and its implications.

  12. The Hubble Constant from SN Refsdal

    Science.gov (United States)

    Vega-Ferrero, J.; Diego, J. M.; Miranda, V.; Bernstein, G. M.

    2018-02-01

    Hubble Space Telescope observations from 2015 December 11 detected the expected fifth counter-image of supernova (SN) Refsdal at z = 1.49. In this Letter, we compare the time-delay predictions from numerous models with the measured value derived by Kelly et al. from very early data in the light curve of the SN Refsdal and find a best value for {H}0={64}-11+9 {km} {{{s}}}-1 {{Mpc}}-1 (68% CL), in excellent agreement with predictions from cosmic microwave background and recent weak lensing data + baryon acoustic oscillations + Big Bang nucleosynthesis (from the DES Collaboration). This is the first constraint on H 0 derived from time delays between multiple-lensed SN images, and the first with a galaxy cluster lens, subject to systematic effects different from other time-delay H 0 estimates. Additional time-delay measurements from new multiply imaged SNe will allow derivation of competitive constraints on H 0.

  13. Marshall Space Flight Center Propulsion Systems Department (PSD) Knowledge Management (KM) Initiative

    Science.gov (United States)

    Caraccioli, Paul; Varnedoe, Tom; Smith, Randy; McCarter, Mike; Wilson, Barry; Porter, Richard

    2006-01-01

    NASA Marshall Space Flight Center's Propulsion Systems Department (PSD) is four months into a fifteen month Knowledge Management (KM) initiative to support enhanced engineering decision making and analyses, faster resolution of anomalies (near-term) and effective, efficient knowledge infused engineering processes, reduced knowledge attrition, and reduced anomaly occurrences (long-term). The near-term objective of this initiative is developing a KM Pilot project, within the context of a 3-5 year KM strategy, to introduce and evaluate the use of KM within PSD. An internal NASA/MSFC PSD KM team was established early in project formulation to maintain a practitioner, user-centric focus throughout the conceptual development, planning and deployment of KM technologies and capabilities within the PSD. The PSD internal team is supported by the University of Alabama's Aging Infrastructure Systems Center of Excellence (AISCE), lntergraph Corporation, and The Knowledge Institute. The principle product of the initial four month effort has been strategic planning of PSD KNI implementation by first determining the "as is" state of KM capabilities and developing, planning and documenting the roadmap to achieve the desired "to be" state. Activities undertaken to suppoth e planning phase have included data gathering; cultural surveys, group work-sessions, interviews, documentation review, and independent research. Assessments and analyses have beon pedormed including industry benchmarking, related local and Agency initiatives, specific tools and techniques used and strategies for leveraging existing resources, people and technology to achieve common KM goals. Key findings captured in the PSD KM Strategic Plan include the system vision, purpose, stakeholders, prioritized strategic objectives mapped to the top ten practitioner needs and analysis of current resource usage. Opportunities identified from research, analyses, cultural1KM surveys and practitioner interviews include

  14. A radiolabeled peptide ligand of the hERG channel, [125I]-BeKm-1

    DEFF Research Database (Denmark)

    Angelo, Kamilla; Korolkova, Yuliya V; Grunnet, Morten

    2003-01-01

    The wild-type scorpion toxin BeKm-1, which selectively blocks human ether-a-go-go related (hERG) channels, was radiolabeled with iodine at tyrosine 11. Both the mono- and di-iodinated derivatives were found to be biologically active. In electrophysiological patch-clamp recordings mono-[127I]-BeKm-1...... had a concentration of half-maximal inhibition (IC50 value) of 27 nM, while wild-type BeKm-1 inhibited hERG channels with an IC50 value of 7 nM. Mono-[125I]-BeKm-1 was found to bind in a concentration-dependent manner and with picomolar affinity to hERG channel protein in purified membrane vesicles...... of [125I]-BeKm-1 to the hERG channel to an IC50 of 7 nM. In autoradiographic studies on rat hearts, binding of [125I]-BeKm-1 was dose-dependent and could partially be displaced by the addition of excess amounts of non-radioactive BeKm-1. The density of the radioactive signal was equally distributed...

  15. Effect of β-alanine supplementation on 20 km cycling time trial performance

    Directory of Open Access Journals (Sweden)

    Ruth Margaret JAMES

    2014-09-01

    Full Text Available The effects of β-alanine supplementation on high-intensity cycling performance and capacity have been evaluated, although the effects on longer duration cycling performance are unclear. Nineteen UK category 1 male cyclists completed four 20 km cycling time trials, two before and two after supplementation with either 6.4 g•d-1 β-alanine (n = 10; BA or a matched placebo (n = 9; P. Performance time for the 20 km time trial and 1 km split times were recorded. There was no significant effect of β-alanine supplementation on 20 km time trial performance (BA-pre 1943 ± 129 s; BA-post 1950 ± 147 s; P-pre 1989 ± 106 s; P-post 1986 ± 115 s or on the performance of each 1 km split. The effect of β-alanine on 20 km time trial performance was deemed unclear as determined by magnitude based inferences. Supplementation with 6.4 g•d-1 of β-alanine for 4 weeks did not affect 20 km cycling time trial performance in well trained male cyclists.

  16. PSR B0329+54: substructure in the scatter-broadened image discovered with RadioAstron on baselines up to 330 000 km

    Science.gov (United States)

    Popov, Mikhail V.; Bartel, Norbert; Gwinn, Carl R.; Johnson, Michael D.; Andrianov, Andrey; Fadeev, Evgeny; Joshi, Bhal Chandra; Kardashev, Nikolay; Karuppusamy, Ramesh; Kovalev, Yuri Y.; Kramer, Michael; Rudnitskiy, Alexey; Shishov, Vladimir; Smirnova, Tatiana; Soglasnov, Vladimir A.; Zensus, J. Anton

    2017-02-01

    We have resolved the scatter-broadened image of PSR B0329+54 and detected a substructure within it. These results are not influenced by any extended structure of a source but instead are directly attributed to the interstellar medium. We obtained these results at 324 MHz with the ground-space interferometer RadioAstron, which included the Space Radio Telescope, ground-based Westerbork Synthesis Radio Telescope and 64-m Kalyazin Radio Telescope on baseline projections up to 330 000 km in 2013 November 22 and 2014 January 1 to 2. At short 15 000 to 35 000 km ground-space baseline projections, the visibility amplitude decreases with baseline length, providing a direct measurement of the size of the scattering disc of 4.8 ± 0.8 mas. At longer baselines, no visibility detections from the scattering disc would be expected. However, significant detections were obtained with visibility amplitudes of 3 to 5 per cent of the maximum scattered around a mean and approximately constant up to 330 000 km. These visibilities reflect a substructure from scattering in the interstellar medium and offer a new probe of ionized interstellar material. The size of the diffraction spot near Earth is 17 000 ± 3 000 km. With the assumption of turbulent irregularities in the plasma of the interstellar medium, we estimate that the effective scattering screen is located 0.6 ± 0.1 of the distance from the Earth towards the pulsar.

  17. Positive Cosmological Constant and Quantum Theory

    Directory of Open Access Journals (Sweden)

    Felix M. Lev

    2010-11-01

    Full Text Available We argue that quantum theory should proceed not from a spacetime background but from a Lie algebra, which is treated as a symmetry algebra. Then the fact that the cosmological constant is positive means not that the spacetime background is curved but that the de Sitter (dS algebra as the symmetry algebra is more relevant than the Poincare or anti de Sitter ones. The physical interpretation of irreducible representations (IRs of the dS algebra is considerably different from that for the other two algebras. One IR of the dS algebra splits into independent IRs for a particle and its antiparticle only when Poincare approximation works with a high accuracy. Only in this case additive quantum numbers such as electric, baryon and lepton charges are conserved, while at early stages of the Universe they could not be conserved. Another property of IRs of the dS algebra is that only fermions can be elementary and there can be no neutral elementary particles. The cosmological repulsion is a simple kinematical consequence of dS symmetry on quantum level when quasiclassical approximation is valid. Therefore the cosmological constant problem does not exist and there is no need to involve dark energy or other fields for explaining this phenomenon (in agreement with a similar conclusion by Bianchi and Rovelli.

  18. Advances in constant-velocity Moessbauer instrumentation

    International Nuclear Information System (INIS)

    Veiga, A.; Martinez, N.; Zelis, P. Mendoza; Pasquevich, G. A.; Sanchez, F. H.

    2006-01-01

    A prototype of a programmable constant-velocity scaler is presented. This instrument allows the acquisition of partial Moessbauer spectra in selected energy regions using standard drivers and transducers. It can be fully operated by a remote application, thus data acquisition can be automated. The instrument consists of a programmable counter and a constant-velocity reference. The reference waveform generator is amplitude modulated with 13-bit resolution, and is programmable in a wide range of frequencies and waveforms in order to optimize the performance of the transducer. The counter is compatible with most standard SCA, and is configured as a rate-meter that provides counts per selectable time slice at the programmed velocity. As a demonstration of the instrument applications, a partial Moessbauer spectrum of a natural iron foil was taken. Only positive energies were studied in 512 channels, accumulating 20 s per channel. A line width of 0.20 mm/s was achieved, performing with an efficiency of 80%.

  19. Local Pain Dynamics during Constant Exhaustive Exercise.

    Directory of Open Access Journals (Sweden)

    Agne Slapsinskaite

    Full Text Available The purpose of this study was to delineate the topological dynamics of pain and discomfort during constant exercise performed until volitional exhaustion. Eleven physical education students were tested while cycling and running at a "hard" intensity level (e.g., corresponding to Borg's RPE (6-20 = 15. During the tests, participants reported their discomfort and pain on a body map every 15s. "Time on task" for each participant was divided into five equal non-overlapping temporal windows within which their ratings were considered for analysis. The analyses revealed that the number of body locations with perceived pain and discomfort increased throughout the five temporal windows until reaching the mean (± SE values of 4.2 ± 0.7 and 4.1 ± 0.6 in cycling and running, respectively. The dominant locations included the quadriceps and hamstrings during cycling and quadriceps and chest during running. In conclusion, pain seemed to spread throughout the body during constant cycling and running performed up to volitional exhaustion with differences between cycling and running in the upper body but not in the lower body dynamics.

  20. Ventricular fibrillation time constant for swine

    International Nuclear Information System (INIS)

    Wu, Jiun-Yan; Sun, Hongyu; Nimunkar, Amit J; Webster, John G; O'Rourke, Ann; Huebner, Shane; Will, James A

    2008-01-01

    The strength–duration curve for cardiac excitation can be modeled by a parallel resistor–capacitor circuit that has a time constant. Experiments on six pigs were performed by delivering current from the X26 Taser dart at a distance from the heart to cause ventricular fibrillation (VF). The X26 Taser is an electromuscular incapacitation device (EMD), which generates about 50 kV and delivers a pulse train of about 15–19 pulses s −1 with a pulse duration of about 150 µs and peak current about 2 A. Similarly a continuous 60 Hz alternating current of the amplitude required to cause VF was delivered from the same distance. The average current and duration of the current pulse were estimated in both sets of experiments. The strength–duration equation was solved to yield an average time constant of 2.87 ms ± 1.90 (SD). Results obtained may help in the development of safety standards for future electromuscular incapacitation devices (EMDs) without requiring additional animal tests

  1. Simple liquid models with corrected dielectric constants

    Science.gov (United States)

    Fennell, Christopher J.; Li, Libo; Dill, Ken A.

    2012-01-01

    Molecular simulations often use explicit-solvent models. Sometimes explicit-solvent models can give inaccurate values for basic liquid properties, such as the density, heat capacity, and permittivity, as well as inaccurate values for molecular transfer free energies. Such errors have motivated the development of more complex solvents, such as polarizable models. We describe an alternative here. We give new fixed-charge models of solvents for molecular simulations – water, carbon tetrachloride, chloroform and dichloromethane. Normally, such solvent models are parameterized to agree with experimental values of the neat liquid density and enthalpy of vaporization. Here, in addition to those properties, our parameters are chosen to give the correct dielectric constant. We find that these new parameterizations also happen to give better values for other properties, such as the self-diffusion coefficient. We believe that parameterizing fixed-charge solvent models to fit experimental dielectric constants may provide better and more efficient ways to treat solvents in computer simulations. PMID:22397577

  2. Holographic dark energy with cosmological constant

    Science.gov (United States)

    Hu, Yazhou; Li, Miao; Li, Nan; Zhang, Zhenhui

    2015-08-01

    Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the ΛHDE model. By studying the ΛHDE model theoretically, we find that the parameters d and Ωhde are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the ΛHDE model by using the recent observational data. We find the model yields χ2min=426.27 when constrained by Planck+SNLS3+BAO+HST, comparable to the results of the HDE model (428.20) and the concordant ΛCDM model (431.35). At 68.3% CL, we obtain -0.07<ΩΛ0<0.68 and correspondingly 0.04<Ωhde0<0.79, implying at present there is considerable degeneracy between the holographic dark energy and cosmological constant components in the ΛHDE model.

  3. Holographic dark energy with cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yazhou; Li, Nan; Zhang, Zhenhui [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190 (China); Li, Miao, E-mail: asiahu@itp.ac.cn, E-mail: mli@itp.ac.cn, E-mail: linan@itp.ac.cn, E-mail: zhangzhh@mail.ustc.edu.cn [School of Astronomy and Space Science, Sun Yat-Sen University, Guangzhou 510275 (China)

    2015-08-01

    Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the ΛHDE model. By studying the ΛHDE model theoretically, we find that the parameters d and Ω{sub hde} are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the ΛHDE model by using the recent observational data. We find the model yields χ{sup 2}{sub min}=426.27 when constrained by Planck+SNLS3+BAO+HST, comparable to the results of the HDE model (428.20) and the concordant ΛCDM model (431.35). At 68.3% CL, we obtain −0.07<Ω{sub Λ0}<0.68 and correspondingly 0.04<Ω{sub hde0}<0.79, implying at present there is considerable degeneracy between the holographic dark energy and cosmological constant components in the ΛHDE model.

  4. Holographic dark energy with cosmological constant

    International Nuclear Information System (INIS)

    Hu, Yazhou; Li, Nan; Zhang, Zhenhui; Li, Miao

    2015-01-01

    Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the ΛHDE model. By studying the ΛHDE model theoretically, we find that the parameters d and Ω hde are divided into a few domains in which the fate of the universe is quite different. We investigate dynamical behaviors of this model, and especially the future evolution of the universe. We perform fitting analysis on the cosmological parameters in the ΛHDE model by using the recent observational data. We find the model yields χ 2 min =426.27 when constrained by Planck+SNLS3+BAO+HST, comparable to the results of the HDE model (428.20) and the concordant ΛCDM model (431.35). At 68.3% CL, we obtain −0.07<Ω Λ0 <0.68 and correspondingly 0.04<Ω hde0 <0.79, implying at present there is considerable degeneracy between the holographic dark energy and cosmological constant components in the ΛHDE model

  5. Modified large number theory with constant G

    International Nuclear Information System (INIS)

    Recami, E.

    1983-01-01

    The inspiring ''numerology'' uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the ''gravitational world'' (cosmos) with the ''strong world'' (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the ''Large Number Theory,'' cosmos and hadrons are considered to be (finite) similar systems, so that the ratio R-bar/r-bar of the cosmos typical length R-bar to the hadron typical length r-bar is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle: according to the ''cyclical big-bang'' hypothesis: then R-bar and r-bar can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P.Caldirola, G. D. Maccarrone, and M. Pavsic

  6. Lepton Collider Operation with Constant Currents

    CERN Document Server

    Wienands, Ulrich

    2005-01-01

    Traditionally, electron-positron colliders have been operating in a top-off-and-coast fashion with a cycle time depending on the beam life time, typically on the order of an hour. Each top-off involves ramping detector systems in addition to the actual filling time. The loss in accumulated luminosity is typically 20-50%. During the last year, both B-Factories have commissioned a continuous-injection mode of operation in which beam is injected without ramping the detector, thus raising luminosity integration by constant operation at peak luminosity. Constant beam currents reduce thermal drift and trips caused by change in beam loading. To achieve this level of operation, special efforts were made to reduce the injection losses and also to implement special gating procedures in the detectors, minimizing dead time. Bunch-injection control decides which bunch to inject into next while maintaining small charge variation between bunches. Beam collimation can reduce injection noise but also cause an increase in back...

  7. PREFACE: Fundamental Constants in Physics and Metrology

    Science.gov (United States)

    Klose, Volkmar; Kramer, Bernhard

    1986-01-01

    This volume contains the papers presented at the 70th PTB Seminar which, the second on the subject "Fundamental Constants in Physics and Metrology", was held at the Physikalisch-Technische Bundesanstalt in Braunschweig from October 21 to 22, 1985. About 100 participants from the universities and various research institutes of the Federal Republic of Germany participated in the meeting. Besides a number of review lectures on various broader subjects there was a poster session which contained a variety of topical contributed papers ranging from the theory of the quantum Hall effect to reports on the status of the metrological experiments at the PTB. In addition, the participants were also offered the possibility to visit the PTB laboratories during the course of the seminar. During the preparation of the meeting we noticed that even most of the general subjects which were going to be discussed in the lectures are of great importance in connection with metrological experiments and should be made accessible to the scientific community. This eventually resulted in the idea of the publication of the papers in a regular journal. We are grateful to the editor of Metrologia for providing this opportunity. We have included quite a number of papers from basic physical research. For example, certain aspects of high-energy physics and quantum optics, as well as the many-faceted role of Sommerfeld's fine-structure constant, are covered. We think that questions such as "What are the intrinsic fundamental parameters of nature?" or "What are we doing when we perform an experiment?" can shed new light on the art of metrology, and do, potentially, lead to new ideas. This appears to be especially necessary when we notice the increasing importance of the role of the fundamental constants and macroscopic quantum effects for the definition and the realization of the physical units. In some cases we have reached a point where the limitations of our knowledge of a fundamental constant and

  8. Drift velocities of 150-km Field-Aligned Irregularities observed by the Equatorial Atmosphere Radar

    Directory of Open Access Journals (Sweden)

    Yuichi Otsuka

    2013-11-01

    Full Text Available Between 130 and 170 km altitude in the daytime ionosphere, the so-called 150-km field-aligned irregularities (FAIs have been observed since the 1960s at equatorial regions with several very high frequency (VHF radars. We report statistical results of 150-km FAI drift velocities on a plane perpendicular to the geomagnetic field, acquired by analyzing the Doppler velocities of 150-km FAIs observed with the Equatorial Atmosphere Radar (EAR at Kototabang, Indonesia during the period from Aug. 2007 to Oct. 2009. We found that the southward/upward perpendicular drift velocity of the 150-km FAIs tends to decrease in the afternoon and that this feature is consistent with that of F-region plasma drift velocities over the magnetic equator. The zonal component of the 150-km FAI drift velocity is westward and decreases with time, whereas the F-region plasma drift velocity observed with the incoherent scatter radar at Jicamarca, Peru, which is westward, reaches a maximum at about noon. The southward/upward and zonal drift velocities of the 150-km FAIs are smaller than that of the F-region plasma drift velocity by approximately 3 m/s and 25 m/s, respectively, on average. The large difference between the 150-km FAI and F-region plasma drift velocities may not arise from a difference in the magnetic latitudes at which their electric fields are generated. Electric fields generated at the altitude at which the 150-km FAIs occur may not be negligible.

  9. Digital optical modules for the KM3NeT neutrino telescope

    Energy Technology Data Exchange (ETDEWEB)

    Kalekin, Oleg [Universitaet Erlangen, ECAP (Germany); Collaboration: ANTARES-KM3NeT-Erlangen-Collaboration

    2015-07-01

    KM3NeT is multi-cubic-kilometer neutrino telescope under construction in the Mediterranean Sea. In the currently running Phase 1 of the project, almost 30 detection units - 700 m tall vertical structures holding 18 Digital Optical Modules (DOMs) each - will be produced and deployed. A KM3NeT DOM consists of a pressure resistant glass sphere encapsulating 31 photomultiplier tubes of 80 mm diameter, readout electronics and additional instrumentation for calibration and monitoring. The Erlangen Centre for Astroparticle Physics is one of the DOM integration sites of the project. This contribution describes the design, functionality and integration procedure of the KM3NeT DOM.

  10. KM3NeT/ARCA sensitivity and discovery potential for neutrino point-like sources

    Directory of Open Access Journals (Sweden)

    Trovato A.

    2016-01-01

    Full Text Available KM3NeT is a large research infrastructure with a network of deep-sea neutrino telescopes in the abyss of the Mediterranean Sea. Of these, the KM3NeT/ARCA detector, installed in the KM3NeT-It node of the network, is optimised for studying high-energy neutrinos of cosmic origin. Sensitivities to galactic sources such as the supernova remnant RXJ1713.7-3946 and the pulsar wind nebula Vela X are presented as well as sensitivities to a generic point source with an E−2 spectrum which represents an approximation for the spectrum of extragalactic candidate neutrino sources.

  11. Blood cholinesterases as human biomarkers of organophosphorus pesticide exposure.

    Science.gov (United States)

    Nigg, H N; Knaak, J B

    2000-01-01

    phosphorothioates and phosphorodithioates (e.g., parathion and azinphosmethyl, respectively) to the more toxic oxons (P = O(S to O)). In some cases, P-450 isozymes catalyze the oxidative cleavage of P-O-aryl bonds (e.g., parathion, methyl parathion, fenitrothion, and diazinon) to form inactive water-soluble alkyl phosphates and aryl leaving groups that are readily conjugated with glucuronic or sulfuric acids and excreted. In addition to the P-450 isozymes, mammalian tissues contain ('A' and 'B') esterases capable of reacting with OPs to produce hydrolysis products or phosphorylated enzymes. 'A'-esterases hydrolyze OPs (i.e., oxons), while 'B'-esterases with serine at the active center are inhibited by OPs. OPs possessing carboxylesters, such as malathion and isofenphos, are hydrolyzed by the direct action of 'B'-esterases (i.e., carboxylesterase, CaE). Metabolic pathways shown for isofenphos, parathion, and malathion define the order in which these reactions occur, while Michaelis-Menten kinetics define reaction parameters (Vmax, K(m)) for the enzymes and substrates involved, and rates of inhibition of 'B'-esterases (kis, bimolecular rate constants) by OPs and their oxons. OPs exert their insecticidal action by their ability to inhibit AChE at the cholinergic synapse, resulting in the accumulation of acetylcholine. The extent to which AChE or other 'B'-esterases are inhibited in workers is dependent upon the rate the OP pesticide is activated (i.e., oxon formation), metabolized to nontoxic products by tissue enzymes, its affinity for AChE and other 'B'-esterases, and esterase concentrations in tissues. Rapid recovery of OP BChE inhibition may be related to reactivation of inhibited forms. AChE, BChE, and CaE appear to function in vivo as scavengers, protecting workers against the inhibition of AChE at synapses. Species sensitivity to OPs varies widely and results in part from binding affinities (Ka) and rates of phosphorylation (kp) rather than rates of activation and detoxif

  12. Search for a Variation of Fundamental Constants

    Science.gov (United States)

    Ubachs, W.

    2013-06-01

    Since the days of Dirac scientists have speculated about the possibility that the laws of nature, and the fundamental constants appearing in those laws, are not rock-solid and eternal but may be subject to change in time or space. Such a scenario of evolving constants might provide an answer to the deepest puzzle of contemporary science, namely why the conditions in our local Universe allow for extreme complexity: the fine-tuning problem. In the past decade it has been established that spectral lines of atoms and molecules, which can currently be measured at ever-higher accuracies, form an ideal test ground for probing drifting constants. This has brought this subject from the realm of metaphysics to that of experimental science. In particular the spectra of molecules are sensitive for probing a variation of the proton-electron mass ratio μ, either on a cosmological time scale, or on a laboratory time scale. A comparison can be made between spectra of molecular hydrogen observed in the laboratory and at a high redshift (z=2-3), using the Very Large Telescope (Paranal, Chile) and the Keck telescope (Hawaii). This puts a constraint on a varying mass ratio Δμ/μ at the 10^{-5} level. The optical work can also be extended to include CO molecules. Further a novel direction will be discussed: it was discovered that molecules exhibiting hindered internal rotation have spectral lines in the radio-spectrum that are extremely sensitive to a varying proton-electron mass ratio. Such lines in the spectrum of methanol were recently observed with the radio-telescope in Effelsberg (Germany). F. van Weerdenburg, M.T. Murphy, A.L. Malec, L. Kaper, W. Ubachs, Phys. Rev. Lett. 106, 180802 (2011). A. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison, J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs, Mon. Not. Roy. Astron. Soc. 403, 1541 (2010). E.J. Salumbides, M.L. Niu, J. Bagdonaite, N. de Oliveira, D. Joyeux, L. Nahon, W. Ubachs, Phys. Rev. A 86, 022510

  13. Statistical Modelling of the Soil Dielectric Constant

    Science.gov (United States)

    Usowicz, Boguslaw; Marczewski, Wojciech; Bogdan Usowicz, Jerzy; Lipiec, Jerzy

    2010-05-01

    The dielectric constant of soil is the physical property being very sensitive on water content. It funds several electrical measurement techniques for determining the water content by means of direct (TDR, FDR, and others related to effects of electrical conductance and/or capacitance) and indirect RS (Remote Sensing) methods. The work is devoted to a particular statistical manner of modelling the dielectric constant as the property accounting a wide range of specific soil composition, porosity, and mass density, within the unsaturated water content. Usually, similar models are determined for few particular soil types, and changing the soil type one needs switching the model on another type or to adjust it by parametrization of soil compounds. Therefore, it is difficult comparing and referring results between models. The presented model was developed for a generic representation of soil being a hypothetical mixture of spheres, each representing a soil fraction, in its proper phase state. The model generates a serial-parallel mesh of conductive and capacitive paths, which is analysed for a total conductive or capacitive property. The model was firstly developed to determine the thermal conductivity property, and now it is extended on the dielectric constant by analysing the capacitive mesh. The analysis is provided by statistical means obeying physical laws related to the serial-parallel branching of the representative electrical mesh. Physical relevance of the analysis is established electrically, but the definition of the electrical mesh is controlled statistically by parametrization of compound fractions, by determining the number of representative spheres per unitary volume per fraction, and by determining the number of fractions. That way the model is capable covering properties of nearly all possible soil types, all phase states within recognition of the Lorenz and Knudsen conditions. In effect the model allows on generating a hypothetical representative of

  14. Development code for group constant processing

    International Nuclear Information System (INIS)

    Su'ud, Z.

    1997-01-01

    In this paper methods, formalism and algorithm related to group constant processing problem from basic library such as ENDF/B VI will be described. Basically the problems can be grouped as follows; the treatment of resolved resonance using NR approximation, the treatment of unresolved resonance using statistical method, the treatment of low lying resonance using intermediate resonance approximation, the treatment of thermal energy regions, and the treatment group transfer matrices cross sections. it is necessary to treat interference between resonance properly especially in the unresolved region. in this paper the resonance problems are treated based on Breit-wigner method, and doppler function is treated using Pade approximation for calculation efficiency. finally, some samples of calculational result for some nuclei, mainly for comparison between many methods are discussed in this paper

  15. Hawking temperature of constant curvature black holes

    International Nuclear Information System (INIS)

    Cai Ronggen; Myung, Yun Soo

    2011-01-01

    The constant curvature (CC) black holes are higher dimensional generalizations of Banados-Teitelboim-Zanelli black holes. It is known that these black holes have the unusual topology of M D-1 xS 1 , where D is the spacetime dimension and M D-1 stands for a conformal Minkowski spacetime in D-1 dimensions. The unusual topology and time-dependence for the exterior of these black holes cause some difficulties to derive their thermodynamic quantities. In this work, by using a globally embedding approach, we obtain the Hawking temperature of the CC black holes. We find that the Hawking temperature takes the same form when using both the static and global coordinates. Also, it is identical to the Gibbons-Hawking temperature of the boundary de Sitter spaces of these CC black holes.

  16. Dielectric Constant Measurements of Solid 4He

    Science.gov (United States)

    Yin, L.; Xia, J. S.; Huan, C.; Sullivan, N. S.; Chan, M. H. W.

    2011-03-01

    Careful measurements of the dielectric properties of solid 4He have been carried out down to 35 mK, considerably lower than the temperature range of previous studies. The sample was prepared from high purity gas with 3He concentrations of the order of 200 ppb and were formed by the blocked capillary method. The molar volume of the sample was 20.30 cm3. The dielectric constant of the samples was found to be independent of temperature down to 120 mK before showing a continuous increase with decreasing temperature and saturating below 50 mK. The total increase in ɛ is 2 parts in 10-5. The temperature dependence of ɛ mimics the increase in the resonant frequency found in the torsional oscillator studies and also the increase found in the shear modulus measurements.

  17. Parallel computational in nuclear group constant calculation

    International Nuclear Information System (INIS)

    Su'ud, Zaki; Rustandi, Yaddi K.; Kurniadi, Rizal

    2002-01-01

    In this paper parallel computational method in nuclear group constant calculation using collision probability method will be discuss. The main focus is on the calculation of collision matrix which need large amount of computational time. The geometry treated here is concentric cylinder. The calculation of collision probability matrix is carried out using semi analytic method using Beckley Naylor Function. To accelerate computation speed some computer parallel used to solve the problem. We used LINUX based parallelization using PVM software with C or fortran language. While in windows based we used socket programming using DELPHI or C builder. The calculation results shows the important of optimal weight for each processor in case there area many type of processor speed

  18. Cosmological constant and general isocurvature initial conditions

    International Nuclear Information System (INIS)

    Trotta, R.; Riazuelo, A.; Durrer, R.

    2003-01-01

    We investigate in detail the question of whether a nonvanishing cosmological constant is required by the present-day cosmic microwave background and large scale structure data when general isocurvature initial conditions are taken into account. We also discuss the differences between the usual Bayesian and the frequentist approaches in data analysis. We show that the Cosmic Background Explorer (COBE)-normalized matter power spectrum is dominated by the adiabatic mode and therefore breaks the degeneracy between initial conditions which is present in the cosmic microwave background anisotropies. We find that in a flat universe the Bayesian analysis requires Ω Λ =e0 to more than 3σ, while in the frequentist approach Ω Λ =0 is still within 3σ for a value of h≤0.48. Both conclusions hold regardless of the initial conditions

  19. Constant-parameter capture-recapture models

    Science.gov (United States)

    Brownie, C.; Hines, J.E.; Nichols, J.D.

    1986-01-01

    Jolly (1982, Biometrics 38, 301-321) presented modifications of the Jolly-Seber model for capture-recapture data, which assume constant survival and/or capture rates. Where appropriate, because of the reduced number of parameters, these models lead to more efficient estimators than the Jolly-Seber model. The tests to compare models given by Jolly do not make complete use of the data, and we present here the appropriate modifications, and also indicate how to carry out goodness-of-fit tests which utilize individual capture history information. We also describe analogous models for the case where young and adult animals are tagged. The availability of computer programs to perform the analysis is noted, and examples are given using output from these programs.

  20. Lepton Collider Operation With Constant Currents

    International Nuclear Information System (INIS)

    Wienands, U.

    2006-01-01

    Electron-positron colliders have been operating in a top-up-and-coast fashion with a cycle time depending on the beam life time, typically one or more hours. Each top-up involves ramping detector systems in addition to the actual filling time. The loss in accumulated luminosity may be 20-50%. During the last year, both B-Factories have commissioned a continuous-injection mode of operation in which beam is injected without ramping the detector, thus raising luminosity integration by always operating at peak luminosity. Constant beam currents also reduce thermal drift and trips caused by change in beam loading. To achieve this level of operation, special efforts were made to reduce the injection losses and also to implement gating procedures in the detectors, minimizing dead time. Beam collimation can reduce injection noise but also cause an increase in background rates. A challenge can be determining beam lifetime, important to maintain tuning of the beams

  1. MODIS/Terra Geolocation Fields 5-Min L1A Swath 1km V005

    Data.gov (United States)

    National Aeronautics and Space Administration — The geolocation fields are calculated for each 1 km MODIS Instantaneous Field of Views (IFOV) for all orbits daily. The locations and ancillary information...

  2. LBA-ECO CD-04 Dendrometry, km 83 Tower Site, Tapajos National Forest, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — A dendrometry study was conducted at the logged forest tower site, km 83 site, Tapajos National Forest, Para, Brazil over a period of 4 years following the...

  3. 14 km Sea Surface Temperature for North America, 1986 - present (NODC Accession 0099042)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This product presents local sea surface temperatures (degrees C). It is a composite gridded-image derived from 8-km resolution SST observations collected by Advanced...

  4. KM3NeT tower data acquisition and data transport electronics

    Science.gov (United States)

    Nicolau, C. A.; Ameli, F.; Biagioni, A.; Capone, A.; Frezza, O.; Lonardo, A.; Masullo, R.; Mollo, C. M.; Orlando, A.; Simeone, F.; Vicini, P.

    2016-04-01

    In the framework of the KM3Net European project, the production stage of a large volume underwater neutrino telescope has started. The forthcoming installation includes 8 towers and 24 strings, that will be installed 100 km off-shore Capo Passero (Italy) at 3500 m depth. The KM3NeT tower, whose layout is strongly based on the NEMO Phase-2 prototype tower deployed in March 2013, has been re-engineered and partially re-designed in order to optimize production costs, power consumption, and usability. This contribution gives a description of the main electronics, including front-end, data transport and clock distribution system, of the KM3NeT tower detection unit.

  5. KM3NeT tower data acquisition and data transport electronics

    Directory of Open Access Journals (Sweden)

    Nicolau C.A.

    2016-01-01

    Full Text Available In the framework of the KM3Net European project, the production stage of a large volume underwater neutrino telescope has started. The forthcoming installation includes 8 towers and 24 strings, that will be installed 100 km off-shore Capo Passero (Italy at 3500 m depth. The KM3NeT tower, whose layout is strongly based on the NEMO Phase-2 prototype tower deployed in March 2013, has been re-engineered and partially re-designed in order to optimize production costs, power consumption, and usability. This contribution gives a description of the main electronics, including front-end, data transport and clock distribution system, of the KM3NeT tower detection unit.

  6. LBA-ECO CD-04 Meteorological and Flux Data, km 83 Tower Site, Tapajos National Forest

    Data.gov (United States)

    National Aeronautics and Space Administration — Tower flux measurements of carbon dioxide,water vapor, heat, and meteorological variables were obtained at the Tapajos National Forest, km 83 site, Santarem, Para,...

  7. Gridded 5km GHCN-Daily Temperature and Precipitation Dataset, Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Gridded 5km GHCN-Daily Temperature and Precipitation Dataset (nClimGrid) consists of four climate variables derived from the GHCN-D dataset: maximum temperature,...

  8. SAFARI 2000 Land Cover from AVHRR, 8-km, 1984 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of a southern African subset of the University of Maryland (UMD) 8-km Global Land Cover product in ASCII GRID and binary image files formats.

  9. LBA Regional Land Cover from AVHRR, 8-km, 1984 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is a subset of an 8-km global land cover product (DeFries et al. 1998). This subset was created for the study area of the Large Scale...

  10. LBA Regional Tree Cover from AVHRR, 1-km, 1992-1993 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set is a subset of the 1-km global tree cover data set (DeFries et al. 1999) developed at the Laboratory for Global Remote Sensing Studies (LGRSS) at the...

  11. LBA Regional Tree Cover from AVHRR, 1-km, 1992-1993 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set is a subset of the 1-km global tree cover data set (DeFries et al. 1999) developed at the Laboratory for Global Remote Sensing Studies...

  12. SAFARI 2000 Tree Cover from AVHRR, 1-km, 1992-1993 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set consists of a southern African subset of the 1-km Global Tree Cover Data Set developed at the Laboratory for Global Remote Sensing Studies (LGRSS) at...

  13. SAFARI 2000 Land Cover from AVHRR, 8-km, 1984 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set consists of a southern African subset of the University of Maryland (UMD) 8-km Global Land Cover product in ASCII GRID and binary image files...

  14. SAFARI 2000 Tree Cover from AVHRR, 1-km, 1992-1993 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set consists of a southern African subset of the 1-km Global Tree Cover Data Set developed at the Laboratory for Global Remote Sensing Studies...

  15. LBA Regional Land Cover from AVHRR, 8-km, 1984 (DeFries et al.)

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set is a subset of an 8-km global land cover product (DeFries et al. 1998). This subset was created for the study area of the Large Scale...

  16. LBA-ECO CD-04 Leaf Litter Data, km 83 Tower Site, Tapajos National Forest, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — Above-ground litter productivity was measured in a 18 ha plot adjacent to the eddy flux tower at the logged forest tower site, km 83, Tapajos National Forest, Para,...

  17. LBA-ECO CD-10 Forest Litter Data for km 67 Tower Site, Tapajos National Forest

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains a single text file which reports litter type and mass in the old-growth upland forest at the Para Western (Santarem) - km 67,...

  18. LBA-ECO CD-04 Leaf Area Index, km 83 Tower Site, Tapajos National Forest, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Leaf area index was estimated in an 18 ha plot at the logged forest tower site, km 83, Tapajos National Forest, Para, Brazil. The plot was adjacent to the...

  19. LBA-ECO CD-04 Leaf Litter Data, km 83 Tower Site, Tapajos National Forest, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Above-ground litter productivity was measured in a 18 ha plot adjacent to the eddy flux tower at the logged forest tower site, km 83, Tapajos National...

  20. LBA-ECO CD-04 Leaf Area Index, km 83 Tower Site, Tapajos National Forest, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — Leaf area index was estimated in an 18 ha plot at the logged forest tower site, km 83, Tapajos National Forest, Para, Brazil. The plot was adjacent to the eddy flux...

  1. Spetsialistid soovitavad kesklinnas piirata sõidukite kiirust 40 km/h-ni / Askur Alas

    Index Scriptorium Estoniae

    Alas, Askur, 1973-

    2004-01-01

    Liiklusspetsialistid soovitavad inimvigastustega õnnetuste vähendamiseks piirata Tallinna kesklinnas kiirust 40 km/h-ni. Linna liiklusteenistus ei pea seda põhjendatuks. Lisa: Helsingi positiivne kogemus

  2. NACP North American 8-km Net Ecosystem Exchange and Component Fluxes, 2004

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides modeled carbon flux estimates at 8-km spatial resolution over North America for the year 2004 of (1) net ecosystem exchange (NEE) of...

  3. NACP North American 8-km Net Ecosystem Exchange and Component Fluxes, 2004

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides modeled carbon flux estimates at 8-km spatial resolution over North America for the year 2004 of (1) net ecosystem exchange (NEE) of carbon...

  4. Internal γ Decay and the Superallowed Branching Ratio for the β+ Emitter Km38

    Science.gov (United States)

    Leach, K. G.; Svensson, C. E.; Ball, G. C.; Leslie, J. R.; Austin, R. A. E.; Bandyopadhyay, D.; Barton, C.; Bassiachvilli, E.; Ettenauer, S.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hackman, G.; Melconian, D.; Morton, A. C.; Mythili, S.; Newman, O.; Pearson, C. J.; Pearson, M. R.; Phillips, A. A.; Savajols, H.; Schumaker, M. A.; Wong, J.

    2008-05-01

    The branching ratio for the superallowed β+ decay of Km38 was measured at TRIUMF’s ISAC radioactive ion beam facility. The M3 internal transition between the isomer and the ground state of Km38 was observed with a branching ratio of 330(43) ppm. A search for the nonanalogue β-decay branch to the first excited 0+ state in Ar38 was also performed and yielded an upper limit of ≤12ppm at 90% C.L. These measurements lead to a revised superallowed branching ratio for Km38 of 99.967(4)%, and increase the Km38 ft value by its entire quoted uncertainty to ft=3052.1(10)s. Implications for tests of the nuclear-structure dependent corrections in superallowed β decays and the extraction of the Cabibbo-Kobayashi-Maskawa matrix element Vud are discussed.

  5. MODIS/Aqua Aerosol 5-Min L2 Swath 10km V006

    Data.gov (United States)

    National Aeronautics and Space Administration — The MODIS/Aqua Aerosol 5-Min L2 Swath 10km (MYD04_L2) product continues to provide full global coverage of aerosol properties from the Dark Target (DT) and Deep Blue...

  6. LBA-ECO CD-10 Temperature Profiles at km 67 Tower Site, Tapajos National Forest

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a single text file which reports temperature measurements at the Para Western (Santarem) - km 67, Primary Forest Tower Site. This site is in...

  7. LBA-ECO CD-10 Temperature Profiles at km 67 Tower Site, Tapajos National Forest

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains a single text file which reports temperature measurements at the Para Western (Santarem) - km 67, Primary Forest Tower Site. This...

  8. LBA-ECO CD-10 Forest Litter Data for km 67 Tower Site, Tapajos National Forest

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains a single text file which reports litter type and mass in the old-growth upland forest at the Para Western (Santarem) - km 67, Primary Forest...

  9. LBA-ECO ND-02 Soil Gas Flux, Rainfall Exclusion, km 67, Tapajos National Forest

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports the results of a rainfall exclusion experiment in the Tapajos National Forest (Flona-Tapajos) at km 67 along the Santarem-Cuiaba...

  10. LBA-ECO ND-02 Soil Gas Flux, Rainfall Exclusion, km 67, Tapajos National Forest

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports the results of a rainfall exclusion experiment in the Tapajos National Forest (Flona-Tapajos) at km 67 along the Santarem-Cuiaba BR-163...

  11. Higgs inflation and the cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Jegerlehner, Fred [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2014-02-15

    The Higgs not only induces the masses of all SM particles, the Higgs, given its special mass value, is the natural candidate for the inflaton and in fact is ruling the evolution of the early universe, by providing the necessary dark energy which remains the dominant energy density. SM running couplings not only allow us to extrapolate SM physics up to the Planck scale, but equally important they are triggering the Higgs mechanism. This is possible by the fact that the bare mass term in the Higgs potential changes sign at about μ{sub 0}≅1.40 x 10{sup 16} GeV and in the symmetric phase is enhanced by quadratic terms in the Planck mass. Such a huge Higgs mass term is able to play a key role in triggering inflation in the early universe. In this article we extend our previous investigation by working out the details of a Higgs inflation scenario. We show how different terms contributing to the Higgs Lagrangian are affecting inflation. Given the SM and its extrapolation to scales μ>μ{sub 0} we find a calculable cosmological constant V(0) which is weakly scale dependent and actually remains large during inflation. This is different to the Higgs fluctuation field dependent ΔV(φ), which decays exponentially during inflation, and actually would not provide a sufficient amount of inflation. The fluctuation field has a different effective mass which shifts the bare Higgs transition point to a lower value μ'{sub 0} ≅7.7 x 10{sup 14} GeV. The vacuum energy V(0) being proportional to M{sub Pl}{sup 4} has a coefficient which vanishes near the Higgs transition point, such that the bare and the renormalized cosmological constant match at this point. The role of the Higgs in reheating and baryogenesis is emphasized.

  12. Universal equations and constants of turbulent motion

    International Nuclear Information System (INIS)

    Baumert, H Z

    2013-01-01

    This paper presents a parameter-free theory of shear-generated turbulence at asymptotically high Reynolds numbers in incompressible fluids. It is based on a two-fluids concept. Both components are materially identical and inviscid. The first component is an ensemble of quasi-rigid dipole-vortex tubes (vortex filaments, excitations) as quasi-particles in chaotic motion. The second is a superfluid performing evasive motions between the tubes. The local dipole motions follow Helmholtz' law. The vortex radii scale with the energy-containing length scale. Collisions between quasi-particles lead either to annihilation (likewise rotation, turbulent dissipation) or to scattering (counterrotation, turbulent diffusion). There are analogies with birth and death processes of population dynamics and their master equations and with Landau's two-fluid theory of liquid helium. For free homogeneous decay the theory predicts the turbulent kinetic energy to follow t −1 . With an adiabatic wall condition it predicts the logarithmic law with von Kármán's constant as 1/√(2 π)= 0.399. Likewise rotating couples form localized dissipative patches almost at rest (→ intermittency) wherein under local quasi-steady conditions the spectrum evolves into an ‘Apollonian gear’ as discussed first by Herrmann (1990 Correlation and Connectivity (Dordrecht: Kluwer) pp 108–20). Dissipation happens exclusively at scale zero and at finite scales this system is frictionless and reminds of Prigogine's (1947 Etude Thermodynamique des Phenomenes Irreversibles (Liege: Desoer) p 143) law of minimum (here: zero) entropy production. The theory predicts further the prefactor of the 3D-wavenumber spectrum (a Kolmogorov constant) as 1/3 (4 π) 2/3 =1.802, well within the scatter range of observational, experimental and direct numerical simulation results. (paper)

  13. Universal equations and constants of turbulent motion

    Science.gov (United States)

    Baumert, H. Z.

    2013-07-01

    This paper presents a parameter-free theory of shear-generated turbulence at asymptotically high Reynolds numbers in incompressible fluids. It is based on a two-fluids concept. Both components are materially identical and inviscid. The first component is an ensemble of quasi-rigid dipole-vortex tubes (vortex filaments, excitations) as quasi-particles in chaotic motion. The second is a superfluid performing evasive motions between the tubes. The local dipole motions follow Helmholtz' law. The vortex radii scale with the energy-containing length scale. Collisions between quasi-particles lead either to annihilation (likewise rotation, turbulent dissipation) or to scattering (counterrotation, turbulent diffusion). There are analogies with birth and death processes of population dynamics and their master equations and with Landau's two-fluid theory of liquid helium. For free homogeneous decay the theory predicts the turbulent kinetic energy to follow t-1. With an adiabatic wall condition it predicts the logarithmic law with von Kármán's constant as 1/\\sqrt {2\\,\\pi }= 0.399 . Likewise rotating couples form localized dissipative patches almost at rest (→ intermittency) wherein under local quasi-steady conditions the spectrum evolves into an ‘Apollonian gear’ as discussed first by Herrmann (1990 Correlation and Connectivity (Dordrecht: Kluwer) pp 108-20). Dissipation happens exclusively at scale zero and at finite scales this system is frictionless and reminds of Prigogine's (1947 Etude Thermodynamique des Phenomenes Irreversibles (Liege: Desoer) p 143) law of minimum (here: zero) entropy production. The theory predicts further the prefactor of the 3D-wavenumber spectrum (a Kolmogorov constant) as \\frac {1}{3}(4\\,\\pi )^{2/3}=1.802 , well within the scatter range of observational, experimental and direct numerical simulation results.

  14. Depth and sharpness variations of 410-km and 660-km discontinuities in North China Craton from dense array ambient noise interferometry

    Science.gov (United States)

    Yao, H.; Feng, J.; Poli, P.; Fang, L.; Wu, Y.

    2017-12-01

    Recent studies have demonstrated that body waves between pairs of stations can be successfully retrieved from ambient noise cross-correlation at both regional and global scales, although surface waves are the dominant signals. However, it is still difficult to use these retrieved body wave signals to map lateral depth variations of main structural discontinuities or velocity contrasts because of its low signal to noise ratio (SNR). In this research, based on a dense seismic array in eastern North China Craton, reflected P-wave signals from 410-km and 660-km discontinuities can be successfully recovered from ambient noise cross-correlation. To improve SNR of the reflected phases, the cross-correlations are stacked within each bin with the phase-weighted stack (PWS) method. In addition, there exist apparent spatial variations of the relative amplitude ratios between the reflected P410P and P660P phases. The retrieved P410P and P660P phases from stacked correlations reveal lateral variations of both depths and sharpness of the 410-km and 660-km discontinuities along two profiles, which may be related with hot material upwelling and the effect of stagnant Pacific plate in the transition zone beneath North China Craton. The imaging results are generally consistent with the results from teleseismic receiver functions, which demonstrate the possibility of mapping high-resolution topography and sharpness of deep internal discontinuities without earthquake-station geometric limitations. Future joint imaging with both interferometric and passive signals will be better for understanding interface architectures and related dynamic processes of the Earth.

  15. Constant Leverage And Constant Cost Of Capital: A Common Knowledge Half-Truth

    Directory of Open Access Journals (Sweden)

    Ignacio Vélez–Pareja

    2008-04-01

    In this document we show that for finite cash flows, Ke and hence WACC depend on the discount rate that is used to value the tax shield, TS and as expected, Ke and WACC are not constant with Kd as the discount rate for the tax shield, even if the leverage is constant. We illustrate this situation with a simple example. We analyze five methods: DCF using APV, FCF and traditional and general formulation for WACC, present value of CFE plus debt and Capital Cash Flow, CCF.

  16. Results of the first detection units of KM3NeT

    Science.gov (United States)

    Biagi, Simone; KM3NeT Collaboration

    2017-12-01

    The KM3NeT collaboration is building a km3-scale neutrino telescope in the Mediterranean Sea. The current phase of construction comprises the deep-sea and onshore infrastructures at two installation sites and the installation of the first detection units for the "ARCA" (Astroparticle Research with Cosmics in the Abyss) and "ORCA" (Oscillation Research with Cosmics in the Abyss) detector. At the KM3NeT-It site, 80 km offshore Capo Passero, Italy, the first 32 detection units for the ARCA detector are being installed and at the KM3Net-Fr site, 40 km offshore Toulon, France, 7 detection units for the ORCA detector will be deployed. The second phase of KM3NeT foresees the completion of ARCA for neutrino astronomy at energies above TeV and ORCA for neutrino mass hierarchy studies at energies in the GeV range. The basic element of the KM3NeT detector is the detection unit. In the ARCA geometry, the detection unit is a 700 m long vertical structure hosting 18 optical modules. Each optical module comprises 31 3 in photomultiplier tubes, instruments to monitor environmental parameters, and the electronic boards for the digitisation of the PMT signals and the management of data acquisition. In their final configuration, both ARCA and ORCA will be composed of about 200 detection units. The first detection unit was installed at the KM3NeT-It site in December 2015. It is active and taking data since its connection to the subsea network. The time of arrival and the duration of photon hits on each of the photomultipliers is measured with a time resolution of 1 ns and transferred onshore where the measurements are processed, triggered and stored on disk. A time calibration procedure, based on data recorded with flashing LED beacons during dedicated periods, allows for time synchronisation of the signals from the optical modules at the nanosecond level. In May 2016, an additional detection unit was installed at the KM3NeT-It site. The first results with two active detection units

  17. Some aspects of preparation and testing of group constants group constant system ABBN-90

    International Nuclear Information System (INIS)

    Nikolaev, M.N.; Tsiboulia, A.M.; Manturov, G.N.

    1996-01-01

    This paper presents an overview of activities performed to prepare and test the group constants ABBN-90. The ABBN-90 set is designed for application calculations of fast, intermediate and thermal nuclear reactors. The calculations of subgroup parameters are discussed. The processing code system GRUCON is mentioned in comparison to the NJOY code system. Proposals are made for future activities. (author). Figs, tabs

  18. The isolated 678-km deep 30 May 2015 MW 7.9 Ogasawara (Bonin) Islands earthquake

    Science.gov (United States)

    Ye, L.; Lay, T.; Zhan, Z.; Kanamori, H.; Hao, J.

    2015-12-01

    Deep-focus earthquakes, located 300 to 700 km below the Earth's surface within sinking slabs of relatively cold oceanic lithosphere, are mysterious phenomena. Seismic radiation from deep events is essentially indistinguishable from that for shallow stick-slip frictional-sliding earthquakes, but the confining pressure and temperature are so high for deep-focus events that a distinct process is likely needed to account for their abrupt energy release. The largest recorded deep-focus earthquake (MW 7.9) in the Izu-Bonin slab struck on 30 May 2015 beneath the Ogasawara (Bonin) Islands, isolated from prior seismicity by over 100 km in depth, and followed by only 2 small aftershocks. Globally, this is the deepest (678 km) major (MW > 7) earthquake in the seismological record. Seismicity indicates along-strike contortion of the Izu-Bonin slab, with horizontal flattening near a depth of 550 km in the Izu region and progressive steepening to near-vertical toward the south above the location of the 2015 event. Analyses of a large global data set of P, SH and pP seismic phases using short-period back-projection, subevent directivity, and broadband finite-fault inversion indicate that the mainshock ruptured a shallowly-dipping fault plane with patchy slip that spread over a distance of ~40 km with variable expansion rate (~5 km/s down-dip initially, ~3 km/s up-dip later). During the 17 s rupture duration the radiated energy was ~3.3 x 1016 J and the stress drop was ~38 MPa. The radiation efficiency is moderate (0.34), intermediate to that of the 1994 Bolivia and 2013 Sea of Okhotsk MW 8.3 earthquakes, indicating a continuum of processes. The isolated occurrence of the event suggests that localized stress concentration associated with the pronounced deformation of the Izu-Bonin slab likely played a role in generating this major earthquake.

  19. Temperature lidar measurements from 1 to 105 km altitude using resonance, Rayleigh, and Rotational Raman scattering

    Directory of Open Access Journals (Sweden)

    M. Alpers

    2004-01-01

    Full Text Available For the first time, three different temperature lidar methods are combined to obtain time-resolved complete temperature profiles with high altitude resolution over an altitude range from the planetary boundary layer up to the lower thermosphere (about 1–105 km. The Leibniz-Institute of Atmospheric Physics (IAP at Kühlungsborn, Germany (54° N, 12° E operates two lidar instruments, using three different temperature measurement methods, optimized for three altitude ranges: (1 Probing the spectral Doppler broadening of the potassium D1 resonance lines with a tunable narrow-band laser allows atmospheric temperature profiles to be determined at metal layer altitudes (80–105 km. (2 Between about 20 and 90 km, temperatures were calculated from Rayleigh backscattering by air molecules, where the upper start values for the calculation algorithm were taken from the potassium lidar results. Correction methods have been applied to account for, e.g. Rayleigh extinction or Mie scattering of aerosols below about 32 km. (3 At altitudes below about 25 km, backscattering in the Rotational Raman lines is strong enough to obtain temperatures by measuring the temperature dependent spectral shape of the Rotational Raman spectrum. This method works well down to about 1 km. The instrumental configurations of the IAP lidars were optimized for a 3–6 km overlap of the temperature profiles at the method transition altitudes. We present two night-long measurements with clear wave structures propagating from the lower stratosphere up to the lower thermosphere.

  20. Price of shifting the Hubble constant

    Science.gov (United States)

    Evslin, Jarah; Sen, Anjan A.; Ruchika

    2018-05-01

    An anisotropic measurement of the baryon acoustic oscillation (BAO) feature fixes the product of the Hubble constant and the acoustic scale H0rd. Therefore, regardless of the dark energy dynamics, to accommodate a higher value of H0 one needs a lower rd and so necessarily a modification of early time cosmology. One must either reduce the age of the Universe at the drag epoch or else the speed of sound in the primordial plasma. The first can be achieved, for example, with dark radiation or very early dark energy, automatically preserving the angular size of the acoustic scale in the cosmic microwave background (CMB) with no modifications to post-recombination dark energy. However, it is known that the simplest such modifications fall afoul of CMB constraints at higher multipoles. As an example, we combine anisotropic BAO with geometric measurements from strong lensing time delays from H0LiCOW and megamasers from the Megamaser Cosmology Project to measure rd, with and without the local distance ladder measurement of H0. We find that the best fit value of rd is indeed quite insensitive to the dark energy model and is also hardly affected by the inclusion of the local distance ladder data.