Infinite dilution conductimetry of plasma and urine: correlation with osmolality.
Genain, C; Tellier, P; Syrota, A; Pocidalo, J J; Hans, M
1978-08-15
The infinite dilution conductivity (IDC) of plasma and urine allows a measurement of the electrolyte content in small samples (5 to 15 microliter). The method was compared to the corrected osmolality (II'p) measured by the freezing-point depression. A linear correlation existed between II'p and the IDC: for plasma: II'p = 13.10 sigma o,p + 37.00 (n = 46 and r = 0.9949) for urine: II'u = 12.75 sigma o,u + 16.56 (n = 85 and r = 0.9504). The measurement of the IDC does not depend on protein concentration and can be used instead of the osmometer methods to determine the total plasma and urine electrolyte content.
Eljack, Mahmoud D; Wilson, Rachael E; Hussam, Abul; Khan, Shahamat U
2015-02-27
Fulvic acid (FA), the most important water soluble fraction of humic substances in nature, is known to form aggregate pseudophase and complexes with organic and inorganic species. Here, we report a novel equilibrium headspace gas chromatography (eHSGC) and a two-step reaction model to measure n-alkylbenzene-FA association constant (K11) and n-alkylbenzene-pseudophase FAn association constant (Kn1) without solute concentration and response factor. The K11 and Kn1 values were 2-3 orders of magnitude higher than those for sodium dodecylsulfate. Changes in peak area were used to calculate the critical FA-aggregation concentration (cfc), mole fraction based partition coefficients (Kx), activity coefficients of solute inside the aggregate pseudophase (γm(∞)), and transfer free energies of alkyl CH2 at infinite dilution. The cfc was found to be 10±0.5μM. The Kx values are of the order of 10(7) in the FA-aggregate pseudophase. The data shows that benzene has the lowest (0.0002) and n-butylbenzene has the highest (0.01) γm(∞) values, which are seven orders of magnitude smaller than γw(∞) in water. The transfer free energy of association of a CH2 group, -155cal/mol, compared to that of benzene, -9722cal/mol, indicates that the FA-aggregate pseudophase is more polarizable benzene-like and less n-alkane aliphatic-like.
Infinitely dilute partial molar properties of proteins from computer simulation.
Ploetz, Elizabeth A; Smith, Paul E
2014-11-13
A detailed understanding of temperature and pressure effects on an infinitely dilute protein's conformational equilibrium requires knowledge of the corresponding infinitely dilute partial molar properties. Established molecular dynamics methodologies generally have not provided a way to calculate these properties without either a loss of thermodynamic rigor, the introduction of nonunique parameters, or a loss of information about which solute conformations specifically contributed to the output values. Here we implement a simple method that is thermodynamically rigorous and possesses none of the above disadvantages, and we report on the method's feasibility and computational demands. We calculate infinitely dilute partial molar properties for two proteins and attempt to distinguish the thermodynamic differences between a native and a denatured conformation of a designed miniprotein. We conclude that simple ensemble average properties can be calculated with very reasonable amounts of computational power. In contrast, properties corresponding to fluctuating quantities are computationally demanding to calculate precisely, although they can be obtained more easily by following the temperature and/or pressure dependence of the corresponding ensemble averages.
Noel, J.M.; Erkey, C.; Bukur, D.B.; Akgerman, A. . Chemical Engineering Dept.)
1994-10-01
The Fischer-Tropsch synthesis (FTS) is a method for converting synthesis gas into petroleum products such as gasoline and diesel fuel. The FTS can be carried out in the gas phase using fixed bed reactors or in the liquid phase in a slurry reactor. Effective pore diffusion is a rate-controlling phenomenon in both reactor types. The authors have utilized the Taylor dispersion technique to measure the infinite dilution mutual diffusion coefficients of 1-octene and 1-tetradecane in subcritical and supercritical ethane and in subcritical propane in the temperature range 293.15--338.15 K and the pressure range 5.52--11.03 MPa. For ethane, the measurements were done on either side of the critical temperature with the pressure above the critical pressure.
Kozłowska, Marta Karolina; Domańska, Urszula; Lempert, Małgorzata; Rogalski, Marek
2005-03-18
The partial molar volumes, V1(M), and the molar volume of isotactic crystalline low-molecular-weight poly(1-butene), iPBu-1, V1, have been calculated from the measured density of {iPBu-1 + solvent (n-hexane, n-heptane, n-nonane, n-decane, p-xylene, cyclohexane and chloroform)} systems. Some of the thermodynamic quantities were also obtained for the iPBu-1 with eight hydrocarbons (n-octane, n-decane, n-undecane, n-dodecane, n-tridecane, o-xylene, m-xylene, p-xylene) by the method of inverse gas chromatography at various temperatures. The weight fraction activity coefficients of the solvent at infinite dilution, omega2(infinity) and the Flory-Huggins thermodynamic interaction parameters, chi21(infinity), between polymer and solvents were determined. The partial molar free energy, deltaG2(infinity), the partial molar heat of mixing, deltaH2(infinity), at infinite dilution and the polymer solubility parameter, delta1, were calculated. Additionally, the (solid + liquid) binary mixtures equilibria, SLE, of iPBu-1 with three hydrocarbons (n-octane, n-decane and m-xylene) were studied by a dynamic method. By performing these experiments over a large concentration range, the T-x phase diagrams of the polymer-solvent systems were constructed. The excess Gibbs energy models were used to describe the nonideal behaviour of the liquid phase. The omega2(infinity) were determined from the solubility measurements and were predicted by using the UNIFAC FV model.
Yang, Jing; Bonomi, Massimiliano; Calero, Carles; Martí, Jordi
2016-04-01
Exploring the free energy landscapes of metal cations on phospholipid membrane surfaces is important for the understanding of chemical and biological processes in cellular environments. Using metadynamics simulations we have performed systematic free energy calculations of sodium cations bound to DMPC phospholipid membranes with cholesterol concentration varying between 0% (cholesterol-free) and 50% (cholesterol-rich) at infinite dilution. The resulting free energy landscapes reveal the competition between binding of sodium to water and to lipid head groups. Moreover, the binding competitiveness of lipid head groups is diminished by cholesterol contents. As cholesterol concentration increases, the ionic affinity to membranes decreases. When cholesterol concentration is greater than 30%, the ionic binding is significantly reduced, which coincides with the phase transition point of DMPC-cholesterol membranes from a liquid-disordered phase to a liquid-ordered phase. We have also evaluated the contributions of different lipid head groups to the binding free energy separately. The DMPC's carbonyl group is the most favorable binding site for sodium, followed by DMPC's phosphate group and then the hydroxyl group of cholesterol.
Glass transition of adsorbed stereoregular PPMA by inverse gas chromatography at infinite dilution
NASA Astrophysics Data System (ADS)
Hamieh, T.; Rezzaki, M.; Grohens, Y.; Schultz, J.
1998-10-01
In this paper, we used inverse gas chromatography (IGC) at infinite dilution that proved to be a powerful technique to determine glass transition and other transitions of PMMA adsorbed on α-alumina. We highlighted the glass transition temperature of the system PMMA/α-Al2O3 with defined polymer tacticity at various covered surface fractions. Thus, the Tg of the adsorbed isotactic PMMA increases strongly as compared to the bulk value. The study of the physical chemical properties of PMMA/α-alumina revealed an important difference in the acidic and basic behaviour, in Lewis terms, of aluminium oxide covered by various concentrations of PMMA. It appears that there is a stabilisation of the physical chemical properties of PMMA/α-Al2O3 for a surface coverage above 50%. This study also highlighted an important effect of the tacticity of the polymer on the acid-base character of the system PMMA/Al2O3. Dans cet article, nous montrons que la chromatographie gazeuse inverse (CGI) à dilution infinie se révèle être une technique très intéressante pour la détermination de la transition vitreuse de polymères stéréoréguliers adsorbés sur des substrats solides tels que l'alumine. Nous avons mis en évidence des transitions attribuées aux phénomènes de relaxation béta, transition vitreuse et autres transitions des systèmes PMMA/Al2O3 de tacticité définie à différents taux de recouvrement. Ainsi, la Tg du PMMA isotactique adsorbé augmente de façon significative par rapport a celle du polymère massique. L'étude des propriétés physico-chimiques du système PMMA/Al2O3, révèle une différence importante dans le comportement acido-basique, au sens de Lewis, de l'alumine pour de taux de recouvrement en PMMA variables. Il apparaît qu'il y a stabilisation des propriétés physico-chimiques de PMMA/Al2O3 pour un taux de recouvrement en PMMA supérieur à 50 %. Cette étude a montré également une influence importante de la tacticité du polymère sur le
Kong, Chang Yi; Siratori, Tomoya; Funazukuri, Toshitaka; Wang, Guosheng
2014-10-01
The effects of temperature and density on retention of platinum(II) 2,4-pentanedionate in supercritical fluid chromatography were investigated at temperatures of 308.15-343.15K and pressure range from 8 to 40MPa by the chromatographic impulse response method with curve fitting. The retention factors were utilized to derive the infinite dilution partial molar volumes of platinum(II) 2,4-pentanedionate in supercritical carbon dioxide. The determined partial molar volumes were small and positive at high pressures but exhibited very large and negative values in the highly compressible near critical region of carbon dioxide.
Measures of correlations in infinite-dimensional quantum systems
NASA Astrophysics Data System (ADS)
Shirokov, M. E.
2016-05-01
Several important measures of correlations of the state of a finite-dimensional composite quantum system are defined as linear combinations of marginal entropies of this state. This paper is devoted to infinite-dimensional generalizations of such quantities and to an analysis of their properties. We introduce the notion of faithful extension of a linear combination of marginal entropies and consider several concrete examples, the simplest of which are quantum mutual information and quantum conditional entropy. Then we show that quantum conditional mutual information can be defined uniquely as a lower semicontinuous function on the set of all states of a tripartite infinite-dimensional system possessing all the basic properties valid in finite dimensions. Infinite-dimensional generalizations of some other measures of correlations in multipartite quantum systems are also considered. Applications of the results to the theory of infinite-dimensional quantum channels and their capacities are considered. The existence of a Fawzi-Renner recovery channel reproducing marginal states for all tripartite states (including states with infinite marginal entropies) is shown. Bibliography: 47 titles.
Wang, Jinyang; Zhong, Haimin; Feng, Huajie; Qiu, Wenda; Chen, Liuping
2014-03-14
The binary infinite dilute diffusion coefficients, D₁₂(∞), of some alkylbenzenes (Ph-C(n), from Ph-H to Ph-C12) from 313 K to 333 K at 15 MPa in supercritical carbon dioxide (scCO2) have been studied by molecular dynamics (MD) simulation. The MD values agree well with the experimental ones, which indicate MD simulation technique is a powerful way to predict and obtain diffusion coefficients of solutes in supercritical fluids. Besides, the local structures of Ph-C(n)/CO2 fluids are further investigated by calculating radial distribution functions and coordination numbers. It qualitatively convinces that the first solvation shell of Ph-C(n) in scCO2 is significantly influenced by the structure of Ph-C(n) solute. Meanwhile, the mean end-to-end distance, the mean radius of gyration and dihedral angle distribution are calculated to gain an insight into the structural properties of Ph-C(n) in scCO2. The abnormal trends of radial distribution functions and coordination numbers can be reasonably explained in term of molecular flexibility. Moreover, the computed results of dihedral angle clarify that flexibility of long-chain Ph-C(n) is the result of internal rotation of C-C single bond (σ(c-c)) in alkyl chain. It is interesting that compared with n-alkane, because of the existence of benzene ring, the flexibility of alkyl chain in Ph-C(n) with same carbon atom number is significantly reduced, as a result, the carbon chain dependence of diffusion behaviors for long-chain n-alkane (n ≥ 5) and long-chain Ph-C(n) (n ≥ 4) in scCO2 are different.
Wang, Jinyang; Zhong, Haimin; Qiu, Wenda; Chen, Liuping; Feng, Huajie
2014-03-14
The binary infinite dilute diffusion coefficients, D{sub 12}{sup ∞}, of some alkylbenzenes (Ph-C{sub n}, from Ph-H to Ph-C{sub 12}) from 313 K to 333 K at 15 MPa in supercritical carbon dioxide (scCO{sub 2}) have been studied by molecular dynamics (MD) simulation. The MD values agree well with the experimental ones, which indicate MD simulation technique is a powerful way to predict and obtain diffusion coefficients of solutes in supercritical fluids. Besides, the local structures of Ph-C{sub n}/CO{sub 2} fluids are further investigated by calculating radial distribution functions and coordination numbers. It qualitatively convinces that the first solvation shell of Ph-C{sub n} in scCO{sub 2} is significantly influenced by the structure of Ph-C{sub n} solute. Meanwhile, the mean end-to-end distance, the mean radius of gyration and dihedral angle distribution are calculated to gain an insight into the structural properties of Ph-C{sub n} in scCO{sub 2}. The abnormal trends of radial distribution functions and coordination numbers can be reasonably explained in term of molecular flexibility. Moreover, the computed results of dihedral angle clarify that flexibility of long-chain Ph-C{sub n} is the result of internal rotation of C-C single bond (σ{sub c-c}) in alkyl chain. It is interesting that compared with n-alkane, because of the existence of benzene ring, the flexibility of alkyl chain in Ph-C{sub n} with same carbon atom number is significantly reduced, as a result, the carbon chain dependence of diffusion behaviors for long-chain n-alkane (n ≥ 5) and long-chain Ph-C{sub n} (n ≥ 4) in scCO{sub 2} are different.
Feng, Huajie; Gao, Wei; Sun, Zhenfan; Lei, Bingxin; Li, Gaonan; Chen, Liuping
2013-10-17
The diffusion coefficients of n-alkanes (from CH4 to C14H30) in near critical and supercritical carbon dioxide at infinite dilution have been studied by molecular dynamics simulation. The simulation results agree well with experiment, which suggests that the simulation method is a powerful tool to obtain diffusion coefficients of solutes in fluids at high pressures. The local structures of such fluids are further investigated by calculating radial distribution functions and coordination numbers. Meanwhile, the dihedral, end-to-end distance and radius of gyration, which are calculated to characterize the flexibility of n-alkanes, are used to reasonably explain the abnormal trends on radial distribution functions and coordination numbers. Moreover, it is found that the flexibility effects on diffusion in pure n-alkanes and infinitely dilute n-alkane/CO2 system are different. The differences in MD simulation results of molecular diffusion in such systems could be qualitatively explained by the flexibility.
Isotropic probability measures in infinite-dimensional spaces
NASA Technical Reports Server (NTRS)
Backus, George
1987-01-01
Let R be the real numbers, R(n) the linear space of all real n-tuples, and R(infinity) the linear space of all infinite real sequences x = (x sub 1, x sub 2,...). Let P sub in :R(infinity) approaches R(n) be the projection operator with P sub n (x) = (x sub 1,...,x sub n). Let p(infinity) be a probability measure on the smallest sigma-ring of subsets of R(infinity) which includes all of the cylinder sets P sub n(-1) (B sub n), where B sub n is an arbitrary Borel subset of R(n). Let p sub n be the marginal distribution of p(infinity) on R(n), so p sub n(B sub n) = p(infinity) (P sub n to the -1 (B sub n)) for each B sub n. A measure on R(n) is isotropic if it is invariant under all orthogonal transformations of R(n). All members of the set of all isotropic probability distributions on R(n) are described. The result calls into question both stochastic inversion and Bayesian inference, as currently used in many geophysical inverse problems.
Measuring dilution of microbicide gels with optical imaging.
Drake, Tyler K; Shah, Tejen; Peters, Jennifer J; Wax, Adam; Katz, David F
2013-01-01
We present a novel approach for measuring topical microbicide gel dilution using optical imaging. The approach compares gel thickness measurements from fluorimetry and multiplexed low coherence interferometry in order to calculate dilution of a gel. As a microbicide gel becomes diluted at fixed thickness, its mLCI thickness measurement remains constant, while the fluorimetry signal decreases in intensity. The difference between the two measurements is related to the extent of gel dilution. These two optical modalities are implemented in a single endoscopic instrument that enables simultaneous data collection. A preliminary validation study was performed with in vitro placebo gel measurements taken in a controlled test socket. It was found that change in slope of the regression line between fluorimetry and mLCI based measurements indicates dilution. A dilution calibration curve was then generated by repeating the test socket measurements with serial dilutions of placebo gel with vaginal fluid simulant. This methodology can provide valuable dilution information on candidate microbicide products, which could substantially enhance our understanding of their in vivo functioning.
Evaluation of heavy water for indicator dilution cardiac output measurement
Schreiner, M.S.; Leksell, L.G.; Neufeld, G.R. )
1989-10-01
We evaluated deuterium oxide (D2O) as a tracer for cardiac output measurements. Cardiac output measurements made by thermodilution were compared with those made by indicator dilution with D2O and indocyanine green as tracers. Five triplicate measurements for each method were made at intervals of 30 minutes in each of 9 anesthetized, mechanically ventilated goats. Cardiac output ranged between 0.68 and 3.79 L/min. The 45 data points yielded a correlation coefficient of 0.948 for the comparison of D2O indicator dilution cardiac output measurements with thermodilution measurements and a linear regression slope of 1.046. D2O indicator dilution measurements were biased by -0.11 +/- 0.22 L/min compared with thermodilution measurements and had a standard deviation of +/- 0.12 L/min for triplicate measurements. Hematocrits ranging between 20 and 50 vol% had no effect on optical density for D2O. D2O is more stable than indocyanine green and approximately one-tenth the price (40 cents per injection compared with $4). The basic instrumentation cost of approximately $9,000 is an additional initial expense, but provides the ability to perform pulmonary extravascular water measurements with a double-indicator dilution technique. D2O has potential as a tracer for the clinical determination of indicator dilution cardiac output measurements and pulmonary extravascular water measurements.
Paduszyński, Kamil
2016-08-22
The aim of the paper is to address all the disadvantages of currently available models for calculating infinite dilution activity coefficients (γ(∞)) of molecular solutes in ionic liquids (ILs)-a relevant property from the point of view of many applications of ILs, particularly in separations. Three new models are proposed, each of them based on distinct machine learning algorithm: stepwise multiple linear regression (SWMLR), feed-forward artificial neural network (FFANN), and least-squares support vector machine (LSSVM). The models were established based on the most comprehensive γ(∞) data bank reported so far (>34 000 data points for 188 ILs and 128 solutes). Following the paper published previously [J. Chem. Inf. Model 2014, 54, 1311-1324], the ILs were treated in terms of group contributions, whereas the Abraham solvation parameters were used to quantify an impact of solute structure. Temperature is also included in the input data of the models so that they can be utilized to obtain temperature-dependent data and thus related thermodynamic functions. Both internal and external validation techniques were applied to assess the statistical significance and explanatory power of the final correlations. A comparative study of the overall performance of the investigated SWMLR/FFANN/LSSVM approaches is presented in terms of root-mean-square error and average absolute relative deviation between calculated and experimental γ(∞), evaluated for different families of ILs and solutes, as well as between calculated and experimental infinite dilution selectivity for separation problems benzene from n-hexane and thiophene from n-heptane. LSSVM is shown to be a method with the lowest values of both training and generalization errors. It is finally demonstrated that the established models exhibit an improved accuracy compared to the state-of-the-art model, namely, temperature-dependent group contribution linear solvation energy relationship, published in 2011 [J. Chem
Paduszyński, Kamil
2016-08-22
The aim of the paper is to address all the disadvantages of currently available models for calculating infinite dilution activity coefficients (γ(∞)) of molecular solutes in ionic liquids (ILs)-a relevant property from the point of view of many applications of ILs, particularly in separations. Three new models are proposed, each of them based on distinct machine learning algorithm: stepwise multiple linear regression (SWMLR), feed-forward artificial neural network (FFANN), and least-squares support vector machine (LSSVM). The models were established based on the most comprehensive γ(∞) data bank reported so far (>34 000 data points for 188 ILs and 128 solutes). Following the paper published previously [J. Chem. Inf. Model 2014, 54, 1311-1324], the ILs were treated in terms of group contributions, whereas the Abraham solvation parameters were used to quantify an impact of solute structure. Temperature is also included in the input data of the models so that they can be utilized to obtain temperature-dependent data and thus related thermodynamic functions. Both internal and external validation techniques were applied to assess the statistical significance and explanatory power of the final correlations. A comparative study of the overall performance of the investigated SWMLR/FFANN/LSSVM approaches is presented in terms of root-mean-square error and average absolute relative deviation between calculated and experimental γ(∞), evaluated for different families of ILs and solutes, as well as between calculated and experimental infinite dilution selectivity for separation problems benzene from n-hexane and thiophene from n-heptane. LSSVM is shown to be a method with the lowest values of both training and generalization errors. It is finally demonstrated that the established models exhibit an improved accuracy compared to the state-of-the-art model, namely, temperature-dependent group contribution linear solvation energy relationship, published in 2011 [J. Chem
Underestimation of access flow by ultrasound dilution flow measurements
NASA Astrophysics Data System (ADS)
Bos, Clemens; Smits, Johannes H. M.; Zijlstra, Jan J.; Blankestijn, Peter J.; Bakker, Chris J. G.; Viergever, Max A.
2002-02-01
For hemodialysis access surveillance, flow measurements are increasingly considered important because they identify accesses at risk of thrombosis. Usually these flow measurements are performed with the ultrasound dilution technique. In a previous patient study it was observed that the resulting flow values were systematically low as compared to magnetic resonance flow measurements, but a satisfactory explanation was lacking. In the present study, we will demonstrate by hemodynamic calculations and in vitro experiments that this discrepancy can be explained by a temporary reduction of the access flow rate, caused by the reversed needle configuration during ultrasound dilution flow measurements. In this configuration, blood is injected retrogressively at one needle and flow between the needles is increased, causing an increased dissipation of energy. The proposed explanation is subsequently confirmed in a patient with a loop graft, by measuring the blood velocity by Doppler ultrasound as a function of reversed dialyzer flow rate. Apart from the ultrasound dilution technique, these findings are applicable to other recently proposed methods for measuring access flow that employ the reversed needle configuration.
NASA Astrophysics Data System (ADS)
Hoshino, H.; Shimada, T.; Yamamoto, M.; Iwase, M.
1992-03-01
In order to obtain the activities of titanium in molten copper at dilute concentrations, i.e., between 5 x 10-6 and 3.4 x 10-3 titanium mole fractions, liquid copper was brought into equilibrium with molten {CaCl2 + Ti2O3} slag saturated with Ti2O3 (s) at 1373 K and the equilibrium oxygen partial pressures were measured by means of a solid-oxide galvanic cell of the type Mo/Mo + MoO2/ZrO2(MgO)/(Cu + Ti)alloy + Ti2O3 + CaCl2 + Ti2O3 slag/Mo The free energy change for the dissolution of solid titanium in molten copper at infinite dilution referred to 1 wt pet was determined as Ti (s) = Ti(1 wt pet in Cu) ΔG°/J = -86,100 ± 8900 at 1373 K
Accuracy of dilution techniques for access flow measurement during hemodialysis.
Krivitski, N M; MacGibbon, D; Gleed, R D; Dobson, A
1998-03-01
Access flow is now widely measured by creating artificial recirculation with the dialysis lines reversed and using dilution methods that sense either ultrasound velocity, electrical impedance, optical, or thermal changes. This study identifies and quantifies factors that influence the accuracy of access flow measurements and recommends ways to reduce these errors. Two major sources of access flow measurement error are identified, arising firstly from the second pass of the indicator by recirculation through the cardiopulmonary system (cardiopulmonary recirculation, CPR), and secondly from changes in venous line blood flow (Qb) and vascular access flow induced by the pressure of venous bolus injections. These errors are considered from theory, by direct measurement of access flow in a sheep model, and by analysis of clinical data. Two extremes for the venous introduction of indicator can be considered in access flow measurements, a slow infusion, which perturbs neither the venous line flow nor access flow but increases the error attributable to the second pass of the indicator by recirculation through cardiopulmonary system, or rapid injection, which eases separation of the second pass of the indicator signal but generates changes in the venous flow and access flow. If CPR is not eliminated, the area added to that of the first pass of indicator ranges up to 40%. Good time resolution could permit the separation of the areas generated by the first and second passage of the indicator. In sheep experiments, injections of 5 or 10 mL into a venous port close to the vascular access caused Qb to change by 20% to 40%. Both the animal experiments and analysis of raw data collected during routine clinical dialysis showed that moving the injection site sufficiently far from the patient, before or into the venous bubble trap, reduced the increase in Qb to only approximately 5% during the critical time when the concentration curve is changing for most tubing brands (Baxter, Belco
Accuracy of dilution techniques for access flow measurement during hemodialysis.
Krivitski, N M; MacGibbon, D; Gleed, R D; Dobson, A
1998-03-01
Access flow is now widely measured by creating artificial recirculation with the dialysis lines reversed and using dilution methods that sense either ultrasound velocity, electrical impedance, optical, or thermal changes. This study identifies and quantifies factors that influence the accuracy of access flow measurements and recommends ways to reduce these errors. Two major sources of access flow measurement error are identified, arising firstly from the second pass of the indicator by recirculation through the cardiopulmonary system (cardiopulmonary recirculation, CPR), and secondly from changes in venous line blood flow (Qb) and vascular access flow induced by the pressure of venous bolus injections. These errors are considered from theory, by direct measurement of access flow in a sheep model, and by analysis of clinical data. Two extremes for the venous introduction of indicator can be considered in access flow measurements, a slow infusion, which perturbs neither the venous line flow nor access flow but increases the error attributable to the second pass of the indicator by recirculation through cardiopulmonary system, or rapid injection, which eases separation of the second pass of the indicator signal but generates changes in the venous flow and access flow. If CPR is not eliminated, the area added to that of the first pass of indicator ranges up to 40%. Good time resolution could permit the separation of the areas generated by the first and second passage of the indicator. In sheep experiments, injections of 5 or 10 mL into a venous port close to the vascular access caused Qb to change by 20% to 40%. Both the animal experiments and analysis of raw data collected during routine clinical dialysis showed that moving the injection site sufficiently far from the patient, before or into the venous bubble trap, reduced the increase in Qb to only approximately 5% during the critical time when the concentration curve is changing for most tubing brands (Baxter, Belco
Temperature variation of the size effect in dilute AlMg and AlCa alloys: Measurement and theory
NASA Astrophysics Data System (ADS)
Gilder, H. M.; Asty, M.; Audit, Ph.
1980-12-01
Optical-interferometric-differential-length and x-ray lattice-parameter measurements performed at low temperatures in dilute AlMg and AlCa alloys indicate that the temperature variation of the size effect corresponds to a relatively large difference between the intrinsic coefficient of thermal expansion βi of the solute atom structure and that, β, of the solvent. This result is another example of the surprising expansive properties of point defects previously described by Gilder and co-workers (high-temperature vacancy diffusion) and more recently by Ganne (low-temperature dilatometry on irradiated specimens). Specifically, in the temperature range 0.2
Measured absorbed dose rates from semi-infinite hemispherical volumes of 133Xe.
Munyon, W J; Barber, D E; Howley, J R
1986-07-01
Surface absorbed dose rates from different hemispheric volumes of 133Xe have been measured directly with an extrapolation chamber. The results indicate that a linear relationship exists between the radius of the cloud volume and the surface absorbed dose rate for radii between 0 and 23 cm. If cloud volumes with radii larger than 23 cm are taken to be infinite with respect to the range of the charged particles emitted, the absorbed dose rate calculated based on that assumption will be within the uncertainty of any measurement of absorbed dose rate that might be made. For hemispheric volumes having radii less than or equal to 23 cm, the surface absorbed dose rate in tissue-equivalent material, in mGy h-1, is approximated (+/- 20%) by the product of [1.30 mGy h-1 cm-1 kBq-1 cm3] X [cloud radius, cm] X [cloud activity concentration, kBq cm-3].
Piccirillo, Bruno; Slussarenko, Sergei; Marrucci, Lorenzo; Santamato, Enrico
2015-01-01
The standard method for experimentally determining the probability distribution of an observable in quantum mechanics is the measurement of the observable spectrum. However, for infinite-dimensional degrees of freedom, this approach would require ideally infinite or, more realistically, a very large number of measurements. Here we consider an alternative method which can yield the mean and variance of an observable of an infinite-dimensional system by measuring only a two-dimensional pointer weakly coupled with the system. In our demonstrative implementation, we determine both the mean and the variance of the orbital angular momentum of a light beam without acquiring the entire spectrum, but measuring the Stokes parameters of the optical polarization (acting as pointer), after the beam has suffered a suitable spin–orbit weak interaction. This example can provide a paradigm for a new class of useful weak quantum measurements. PMID:26477715
DOE R&D Accomplishments Database
Nambu, Y.
1967-01-01
The main ingredients of the method of infinite multiplets consist of: 1) the use of wave functions with an infinite number of components for describing an infinite tower of discrete states of an isolated system (such as an atom, a nucleus, or a hadron), 2) the use of group theory, instead of dynamical considerations, in determining the properties of the wave functions.
NASA Technical Reports Server (NTRS)
Backus, George
1987-01-01
Let R be the real numbers, R(n) the linear space of all real n-tuples, and R(infinity) the linear space of all infinite real sequences x = (x sub 1, x sub 2,...). Let P sub n :R(infinity) approaches R(n) be the projection operator with P sub n (x) = (x sub 1,...,x sub n). Let p(infinity) be a probability measure on the smallest sigma-ring of subsets of R(infinity) which includes all of the cylinder sets P sub n(-1) (B sub n), where B sub n is an arbitrary Borel subset of R(n). Let p sub n be the marginal distribution of p(infinity) on R(n), so p sub n(B sub n) = p(infinity)(P sub n to the -1(B sub n)) for each B sub n. A measure on R(n) is isotropic if it is invariant under all orthogonal transformations of R(n). All members of the set of all isotropic probability distributions on R(n) are described. The result calls into question both stochastic inversion and Bayesian inference, as currently used in many geophysical inverse problems.
NASA Astrophysics Data System (ADS)
Gallot, T.; Fehler, M. C.; Brown, S. R.; Buns, D.; Szabo, T.; Malcolm, A. E.
2013-12-01
The nonlinear mechanical behavior of rocks is a well known phenomenon at a laboratory scale and has been observed during earthquakes, slow slip events, volcanic activity, reservoir fracturing, etc. he present work explores the possibility of measuring nonlinear parameters in a semi-infinite medium. Contrary to existing methods that rely on vibrating a sample at a fixed resonant frequency, a pulsed wave is used to create a high amplitude perturbation (the pump) responsible for the nonlinear response. At the same time, a low amplitude wave probes the material to measure changes in elastic properties. Laboratory experiments have been performed in rocks (berea sandstones) to explore the possibility of using such a method for Earth imaging. The strain created by the pump (a shear wave in the tens of kHz), is on the order of a microstrain and is measured by laser vibrometry and extrapolated to the whole sample by a finite difference simulation. A compressional pulse (in the hundreds of kHz range) probes the 15-cm size sample. The variation in time of flight is related to a change in elasticity as described as a function of the strain through quadratic and cubic nonlinearities. Those nonlinear coefficients are shown to be sensitive to several environmental parameters such as temperature, humidity, and also physical properties such as the amplitude of the strain and the relative orientation of the pump and the probing wave. Experimental set-up: a P-wave transducer generates an ultrasonic pulse at 500 kHz recorded by an identical transducer after propagation through the sample. The medium is then perturbed with a S-wave transducer on the top of the sample at 50 kHz .
NASA Astrophysics Data System (ADS)
Tzamkiozis, T.; Ntziachristos, L.; Amanatidis, S.; Niemelä, V.; Ukkonen, A.; Samaras, Z.
2013-08-01
This paper presents a new concept of a partial flow sampling system (PFSS), involving a two-stage diluter which operates on the principle of underpressure, while exhaust is sampled through a capillary. Due to the low flowrate through the capillary, the diluter may be sampling from a freely exhausting tailpipe and is not prone to pressure variations in the exhaust line. In addition, the PFSS operates at constant pressure conditions even upstream of diesel particle filters that increase the backpressure in the tailpipe. As a result, the PFSS offers a constant dilution ratio (DR) over any engine or vehicle operation condition. This study presents the diluter concept and a straightforward model developed to calculate the DR, depending on the dilution air flowrate and the diluter underpressure. The model is validated using CO2 as a trace gas, and very good agreement is demonstrated between the calculated and the measured DR values. Following validation, the PFSS is combined with aerosol measurement instruments to measure the exhaust particle concentration of a diesel engine operating at different steady-state modes. For demonstrating the stability of the DR and applicability of the PFSS, measurements are conducted with both heavy duty and light duty diesel exhaust gases. Future applications of this device include gas and particle exhaust measurements both in laboratory environments and on-board vehicles.
Measuring the Soret coefficient of nanoparticles in a dilute suspension
Zhao, Chao; Fu, Jinxin; Oztekin, Alparslan; Cheng, Xuanhong
2014-01-01
Thermophoresis is an efficient process for the manipulation of molecules and nanoparticles due to the strong force it generates on the nanoscale. Thermophoresis is characterized by the Soret coefficient. Conventionally, the Soret coefficient of nanosized species is obtained by fitting the concentration profile under a temperature gradient at the steady state to a continuous phase model. However, when the number density of the target is ultralow and the dispersed species cannot be treated as a continuous phase, the bulk concentration fluctuates spatially, preventing extraction of temperature-gradient induced concentration profile. The present work demonstrates a strategy to tackle this problem by superimposing snapshots of nanoparticle distribution. The resulting image is suitable for the extraction of the Soret coefficient through the conventional data fitting method. The strategy is first tested through a discrete phase model that illustrates the spatial fluctuation of the nanoparticle concentration in a dilute suspension in response to the temperature gradient. By superimposing snapshots of the stochastic distribution, a thermophoretic depletion profile with low standard error is constructed, indicative of the Soret coefficient. Next, confocal analysis of nanoparticle distribution in response to a temperature gradient is performed using polystyrene nanobeads down to 1e-5% (v/v). The experimental results also reveal that superimposing enhances the accuracy of extracted Soret coefficient. The critical particle number density in the superimposed image for predicting the Soret coefficient is hypothesized to depend on the spatial resolution of the image. This study also demonstrates that the discrete phase model is an effective tool to study particle migration under thermophoresis in the liquid phase. PMID:25221433
Thermal dilution measurement of cardiac output in dogs using an analog computer.
Hendriks, F F; Schipperheyn, J J; Quanjer, P H
1978-01-01
Thermal dilution cardiac output determinations in dogs were compared to simultaneously performed Fick oxygen measurements. The purpose of this study was to validate in dog experiments a method for thermal dilution measurement which employs a double-thermistor catheter combined with an automatic computer as described by Olsson et al. Dilution and injectate temperature are entered directly into the calculation. The method does not employ logarithmic extrapolation, integration of the dilution signal being terminated when a preset cut-off level is reached. Errors due to recirculation, thermal capacitance of the right heart and heat exchange with the catheter's dead space require the use of an empirically derived correction factor, which in dogs was found to be significantly different from the factor used for human thermal dilution curves. With the appropriate cut-off level and correction factor a good agreement was found between the results of the thermal dilution and the Fick method. The regression equation for 47 experiments was found to be COtd = 0.95 COFick + 0.08; the correlation coefficient was 0.94. PMID:728031
Haridas, Divya; P, Vibin Antony; Sajith, V.; Sobhan, C. B.
2014-10-15
Interferometric method, which utilizes the interference of coherent light beams, is used to determine the temperature distribution in the vicinity of a vertical heater plate. The optical components are arranged so as to obtain wedge fringe and infinite fringe patterns and isotherms obtained in each case were compared. In wedge fringe setting, image processing techniques has been used for obtaining isotherms by digital subtraction of initial parallel fringe pattern from deformed fringe pattern. The experimental results obtained are compared with theoretical correlations. The merits and demerits of the fringe analysis techniques are discussed on the basis of the experimental results.
NASA Astrophysics Data System (ADS)
Haridas, Divya; P, Vibin Antony; Sajith, V.; Sobhan, C. B.
2014-10-01
Interferometric method, which utilizes the interference of coherent light beams, is used to determine the temperature distribution in the vicinity of a vertical heater plate. The optical components are arranged so as to obtain wedge fringe and infinite fringe patterns and isotherms obtained in each case were compared. In wedge fringe setting, image processing techniques has been used for obtaining isotherms by digital subtraction of initial parallel fringe pattern from deformed fringe pattern. The experimental results obtained are compared with theoretical correlations. The merits and demerits of the fringe analysis techniques are discussed on the basis of the experimental results.
Dye tracers as a tool for outfall studies: dilution measurement approach.
Pecly, J O G; Roldão, J S F
2013-01-01
Dye tracer technique is well established and of wide application for assessment of outfalls and for delineation of near field and far field extensions. Common goals of a tracer study include the measurement of the dilution factor, estimation of the dispersion coefficients, measurement of the effluent discharge and calibration of a contaminant transport model. This paper presents a brief review of the methods involving the use of dye tracer for outfall assessment and illustrates the methods of slug release and continuous injection based on two real cases of campaigns carried out on Brazilian coastal waters. Slug injection on the surface of the water body was used for preliminary dispersion studies aiming at outfall positioning. During the operational phase of an outfall, the continuous injection of dye tracer was used to determine effluent dilution in different seasons. In coastal waters of Rio de Janeiro city, sea current pattern, tidal modulation and thermal stratification explained the main features of the dilution field.
This environmental research brief reports on innovative measures for addressing 1) the source zone soils, 2) the concentrated portion of the ground-water plume, and 3) the dilute portion of the ground-water plume. For the source zone, surfactant-enhanced chromium extraction is ev...
Depletion potential in the infinite dilution limit
NASA Astrophysics Data System (ADS)
Yuste, Santos Bravo; Santos, Andrés; López de Haro, Mariano
2008-04-01
The depletion force and depletion potential between two in principle unequal "big" hard spheres embedded in a multicomponent mixture of "small" hard spheres are computed using the rational function approximation method for the structural properties of hard-sphere mixtures [S. B. Yuste, A. Santos, and M. López de Haro, J. Chem. Phys. 108, 3683 (1998)]. The cases of equal solute particles and of one big particle and a hard planar wall in a background monodisperse hard-sphere fluid are explicitly analyzed. An improvement over the performance of the Percus-Yevick theory and good agreement with available simulation results are found.
Kawaguchi, Migaku; Eyama, Sakae; Takatsu, Akiko
2014-08-01
A candidate reference measurement procedure involving automated isotope dilution coupled with liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) with on-line dilution and solid phase extraction (SPE) has been developed and critically evaluated. We constructed the LC-MS/MS with on-line dilution and SPE system. An isotopically labelled internal standard, cortisol-d4, was added to serum sample. After equilibration, the methanol was added to the sample, and deproteination was performed. Then, the sample was applied to the LC-MS/MS system. The limit of detection (LOD) and limit of quantification (LOQ) were 0.2 and 1ngg(-1), respectively. Excellent precision was obtained with within-day variation (RSD) of 1.9% for ID-LC-MS/MS analysis (n=6). This method, which demonstrates simple, easy, good accuracy, high precision, and is free from interferences from structural analogues, qualifies as a reference measurement procedure.
Taylor, Diane M; Chow, Fotini K; Delkash, Madjid; Imhoff, Paul T
2016-10-01
Landfills are a significant contributor to anthropogenic methane emissions, but measuring these emissions can be challenging. This work uses numerical simulations to assess the accuracy of the tracer dilution method, which is used to estimate landfill emissions. Atmospheric dispersion simulations with the Weather Research and Forecast model (WRF) are run over Sandtown Landfill in Delaware, USA, using observation data to validate the meteorological model output. A steady landfill methane emissions rate is used in the model, and methane and tracer gas concentrations are collected along various transects downwind from the landfill for use in the tracer dilution method. The calculated methane emissions are compared to the methane emissions rate used in the model to find the percent error of the tracer dilution method for each simulation. The roles of different factors are examined: measurement distance from the landfill, transect angle relative to the wind direction, speed of the transect vehicle, tracer placement relative to the hot spot of methane emissions, complexity of topography, and wind direction. Results show that percent error generally decreases with distance from the landfill, where the tracer and methane plumes become well mixed. Tracer placement has the largest effect on percent error, and topography and wind direction both have significant effects, with measurement errors ranging from -12% to 42% over all simulations. Transect angle and transect speed have small to negligible effects on the accuracy of the tracer dilution method. These tracer dilution method simulations provide insight into measurement errors that might occur in the field, enhance understanding of the method's limitations, and aid interpretation of field data. PMID:27395754
Taylor, Diane M; Chow, Fotini K; Delkash, Madjid; Imhoff, Paul T
2016-10-01
Landfills are a significant contributor to anthropogenic methane emissions, but measuring these emissions can be challenging. This work uses numerical simulations to assess the accuracy of the tracer dilution method, which is used to estimate landfill emissions. Atmospheric dispersion simulations with the Weather Research and Forecast model (WRF) are run over Sandtown Landfill in Delaware, USA, using observation data to validate the meteorological model output. A steady landfill methane emissions rate is used in the model, and methane and tracer gas concentrations are collected along various transects downwind from the landfill for use in the tracer dilution method. The calculated methane emissions are compared to the methane emissions rate used in the model to find the percent error of the tracer dilution method for each simulation. The roles of different factors are examined: measurement distance from the landfill, transect angle relative to the wind direction, speed of the transect vehicle, tracer placement relative to the hot spot of methane emissions, complexity of topography, and wind direction. Results show that percent error generally decreases with distance from the landfill, where the tracer and methane plumes become well mixed. Tracer placement has the largest effect on percent error, and topography and wind direction both have significant effects, with measurement errors ranging from -12% to 42% over all simulations. Transect angle and transect speed have small to negligible effects on the accuracy of the tracer dilution method. These tracer dilution method simulations provide insight into measurement errors that might occur in the field, enhance understanding of the method's limitations, and aid interpretation of field data.
Pleural liquid clearance rate measured in awake sheep by the volume of dilution method
Broaddus, V.C.; Wiener-Kronish, J.P.; Berthiaume, Y.; Staub, N.C.
1986-03-01
The authors reported 24h clearance of mock pleural effusions measured terminally in sheep. To measure effusion volume at different times in the same sheep, they injected /sup 111/In-transferrin and measured its dilution. In 5 sheep with effusions of known sizes, the method was accurate to +/-10%. In 5 awake sheep, the authors injected 10 ml/kg of a 1% protein solution via a non-penetrating rib capsule. At 6h, the authors measured the volume by the dilution method and at 24h by direct recovery. The clearance rate in each animal was constant at 2.9-6.0%/h (average 4.8 +/- 1.3%/h). This new method gives a reliable two point clearance rate and requires fewer animals.
iFit and Light Dilution: Ultraviolet volcanic SO2 measurements under the microscope
NASA Astrophysics Data System (ADS)
Burton, Michael; Sawyer, Georgina
2013-04-01
Volcanic SO2 flux measurement systems are a staple of volcano monitoring networks, as this volcanic gas flux reflects the magma input rate into the volcano's feeding system. SO2 flux monitoring has been used since the seventies, with some notable successes at Pinatubo, Mt. St. Helens, Montserrat and Italian volcanoes. However, there are some subtle aspects of the atmospheric radiative transfer processed inherent in the technique which have been ignored for many years; or perhaps better, they have been forgotten, as these subtleties were clearly spelt out in early COSPEC papers by Millán and co-workers. Recent work by Kern et al. (2010, 2012) has re-focussed attention on the light dilution effect during SO2 plume measurements. This occurs when solar radiation is scattered into the slant column observed by a UV spectrometer or imaging system below the height of the volcanic plume, such that it has not passed through the plume. This below-plume light dilutes the SO2 absorption produced by light passing through the plume from above, apparently reducing the amount of SO2 present. Fortunately, the light dilution process leaves a signature in the shape of the SO2 absorption spectrum, due to the non-linear behaviour of absorption lines with respect to gas amount, following the Beer-Lamber law. This signature can be used to quantify the magnitude of the light dilution in real field spectra. We developed a new intensity spectrum UV fitting code called iFit that allows fitting of the light dilution signature, and applied this to examples from Stromboli and Etna. here we summarise the results from these studies and highlight the importance of this previously ignored process for quantify SO2 gas emissions from volcanoes.
Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames
Weiland, N.T.; Strakey, P.A.
2007-03-01
Turbulent hydrogen diffusion flames diluted with nitrogen are currently being studied to assess their ability to achieve the DOE Turbine Program’s aggressive emissions goal of 2 ppm NOx in a hydrogen-fueled IGCC gas turbine combustor. Since the unstrained adiabatic flame temperatures of these diluted flames are not low enough to eliminate thermal NOx formation the focus of the current work is to study how the effects of flame residence time and global flame strain can be used to help achieve the stated NOx emissions goal. Dry NOx measurements are presented as a function of jet diameter nitrogen dilution and jet velocity for a turbulent hydrogen/nitrogen jet issuing from a thin-lipped tube in an atmospheric pressure combustor. The NOx emission indices from these experiments are normalized by the flame residence time to ascertain the effects of global flame strain and fuel Lewis Number on the NOx emissions. In addition dilute hydrogen diffusion flame experiments were performed in a high-pressure combustor at 2 4 and 8 atm. The NOx emission data from these experiments are discussed as well as the results from a Computational Fluid Dynamics modeling effort currently underway to help explain the experimental data.
Structure of Finite-RSB Asymptotic Gibbs Measures in the Diluted Spin Glass Models
NASA Astrophysics Data System (ADS)
Panchenko, Dmitry
2016-01-01
We suggest a possible approach to proving the Mézard-Parisi formula for the free energy in the diluted spin glass models, such as diluted K-spin or random K-sat model at any positive temperature. In the main contribution of the paper, we show that a certain small modification of the Hamiltonian in any of these models forces all finite-RSB asymptotic Gibbs measures in the sense of the overlaps to satisfy the Mézard-Parisi ansatz for the distribution of spins. Unfortunately, what is still missing is a description of the general full-RSB asymptotic Gibbs measures. If one could show that the general case can be approximated by finite-RSB case in the right sense then one could a posteriori remove the small modification of the Hamiltonian to recover the Mézard-Parisi formula for the original model.
Bancon-Montigny, Chrystelle; Maxwell, Paulette; Yang, Lu; Mester, Zoltán; Sturgeon, Ralph E
2002-11-01
A unique approach was developed to improve the precision of quantification of tributyltin (TBT) in sedimentsby solid phase microextraction (SPME) using isotope dilution GC/MS. The precision of the analytical technique was initially evaluated using standard calibration solutions. In selective ion monitoring (SIM) mode, the relative standard deviation (RSD) obtained for TBT based on peak area response was 18% (n = 11). When an internal standard, tripropyltin (TPrT), was used, the RSD decreased to 12%. A significant improvement in the precision using SPME was noted when a 117Sn-enriched TBT spike was employed; the RSD decreased 4-fold to 3%. Detection limits of 0.2 and 20 ng(Sn) L(-1) were achieved with SPME sampling and liquid-liquid extraction, respectively. Six analyses were performed for determination of TBT in PACS-2 sediment Certified Reference Material using both standard additions and isotope dilution procedures. For the latter, a 117Sn-enriched TBT spike was used. A concentration of 0.88 +/- 0.03 microg g(-1) (RSD 3.4%) obtained using standard additions was in good agreement with the certified value of 0.98 +/- 0.13 microg g(-1) as tin. Concentrations found using isotope dilution were 0.895 +/- 0.015 microg g(-1) (RSD 1.73%) as tin and 0.874 +/- 0.014 microg g(-1) (RSD 1.66%) as tin using a liquid-liquid extraction and SPME sampling, respectively. A 2-fold improvement in the precision of TBT concentration measurement using isotope dilution was clearly achieved, demonstrating its superiority in providing more accurate and precise results as compared to the method of standard additions. The isotope dilution technique eliminated the problem of poor reproducibility, which typically plagues SPME. PMID:12433095
Short course on St-02 applications of isotope dilutions and isotopic measurements
Miller, P.
1998-01-05
This short course includes information on these topics and subtopics: (I) Nuclear Properties: (A) Historic roots; (B) Nomenclature; (C) Nuclear Stability and abundance; (D) Uses of isotopic techniques; (II) Instrumentation: (A) Sources; (B) Mass resolving elements; (C) Detectors; (III) Making Isotopic Measurements by ICP-MS: (A) Deadtime Correction; (B) Mass Discrimination; (C) Signal /Noise considerations; (IV) Applications and examples: (A) Isotope dilution; (B) Double Spike; (C) Biological Application; (D) Environmental Application; (E) Geological.
NASA Technical Reports Server (NTRS)
Socolovsky, Eduardo A.; Bushnell, Dennis M. (Technical Monitor)
2002-01-01
The cosine or correlation measures of similarity used to cluster high dimensional data are interpreted as projections, and the orthogonal components are used to define a complementary dissimilarity measure to form a similarity-dissimilarity measure pair. Using a geometrical approach, a number of properties of this pair is established. This approach is also extended to general inner-product spaces of any dimension. These properties include the triangle inequality for the defined dissimilarity measure, error estimates for the triangle inequality and bounds on both measures that can be obtained with a few floating-point operations from previously computed values of the measures. The bounds and error estimates for the similarity and dissimilarity measures can be used to reduce the computational complexity of clustering algorithms and enhance their scalability, and the triangle inequality allows the design of clustering algorithms for high dimensional distributed data.
Three-terminal capacitance cell for stopped-flow measurements of very dilute solutions
NASA Astrophysics Data System (ADS)
Tjahjono, Martin; Davis, Thomas; Garland, Marc
2007-02-01
A capacitance cell has been designed, constructed, and tested for stopped-flow measurements of very dilute low-relative permittivity liquid solutions. The capacitance cell utilizes a three-terminal design and is connected to ultrahigh sensitivity capacitance bridge. The cell was designed for operating conditions T ≈243.15-373.15K and P ≈0-1MPa and tested with pure anhydrous cyclohexane and with dilute acetone/cyclohexane solutions at 298.15K and 0.1MPa under an argon blanket in a thermostated bath with a temperature variation of <0.001K. Details of the design and materials of construction are reported. The measured relative permittivity of cyclohexane was 2.015 565, in agreement with the literature, and the long term variation of the measurement was ±5×10-6. The relative permittivities of the acetone/cyclohexane solutions were very linear (R2=0.9997) in the measured interval of 0.001-0.008mole fraction. These measurements confirm that the design specifications for stability and resolution/sensitivity of better than 1×10-5 have been realized. Finally, the present online capacitance cell was connected online to an ultrasensitive densitometer and ultrasensitive refractometer and binary acetone/cyclohexane solutions were measured. The measurements of density, refractive index, and relative permittivity were combined to provide a dipole moment of acetone of 2.750±0.005D, which is in good agreement with literature.
Automated measurement of respiratory gas exchange by an inert gas dilution technique
NASA Technical Reports Server (NTRS)
Sawin, C. F.; Rummel, J. A.; Michel, E. L.
1974-01-01
A respiratory gas analyzer (RGA) has been developed wherein a mass spectrometer is the sole transducer required for measurement of respiratory gas exchange. The mass spectrometer maintains all signals in absolute phase relationships, precluding the need to synchronize flow and gas composition as required in other systems. The RGA system was evaluated by comparison with the Douglas bag technique. The RGA system established the feasibility of the inert gas dilution method for measuring breath-by-breath respiratory gas exchange. This breath-by-breath analytical capability permits detailed study of transient respiratory responses to exercise.
NASA Astrophysics Data System (ADS)
Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.
2013-08-01
An important starting point for designing management improvements, particularly in irrigation areas, is to record the baseline state of the water resources, including the amount of discharge from canals. In this respect discharge measurements by means of the salt dilution method is a traditional and well-documented technique. However, this methodology can be strongly influenced by the natural streaming characteristics of the canal (e.g. laminar vs. turbulent flow) and accurate precautions must be considered in the choice of both the measuring section and the length of the measuring reach of the canal which can affect the plume shape. The knowledge of plume distribution in the measuring cross-section is of primary importance for a correct location of sampling points aimed in obtaining a reliable measurement. To obtain this, geophysical imaging of an NaCl plume from a slug-injection salt dilution test has been performed within this paper by means of cross-flow fast electric resistivity tomography (FERT) in a real case history. Direct sampling of the same plume has been also performed with a multisampling optimization technique to obtain an average value over the measuring section by means of contemporarily sampling water in nine points. Results show that a correct visualization of the passage of the salt plume is possible by means of geophysical controls and that this can potentially help in the correct location of sampling points.
Hirtz, P.; Lovekin, J.
1995-12-31
The tracer dilution technique for the measurement of steam and water mass flowrates and total enthalpy of two-phase geothermal fluids has been in routine use in the U.S.A. for almost three years. The tracer technique was first tested and adopted on a field-wide basis at the Coso geothermal field in California. Validation of the method was performed at the Roosevelt Hot Springs geothermal project in Utah and the Salton Sea and Heber geothermal projects in California by direct comparison to orifice-plate flowmeter measurements of the separated phases. Production well mass flowrates and total enthalpy are now regularly measured by this technique in the Coso, Salton Sea and Heber geothermal fields. Implementation of the tracer method is currently underway for the Tiwi and Bulalo geothermal fields in the Philippines. This paper presents the conceptual design of the measurement process, the results of field validations, and operating experience during field-wide testing in Coso.
Fernandez-Fernandez, Alicia; Carvajal, Denny A.; Lei, Tingjun; McGoron, Anthony J.
2014-01-01
Anthracyclines cause severe irreversible cardiac toxicity. The study of changes in cardiac permeability with chemotherapy could enhance the understanding of mechanisms behind cardiac damage, and provide useful information to evaluate anthracycline cardiotoxicity. Thirty-six rats (12 Sprague-Dawley, 12 Wistar, 12 Fischer-344) were randomly assigned to control (n= 21) or doxorubicin (n = 15), and injected i.p. with a cumulative dose of 18 mg/kg doxorubicin in saline (vehicle) or vehicle over 12 days. Echocardiography was performed at baseline and on day 11. An isolated heart experiment was done on day 12 to obtain perfused heart pressure values, and to measure cardiac capillary permeability using a Texas Red/sodium fluorescein multiple indicator dilution method. Control animals had significantly lower average permeability-surface-area-products (0.035±0.013 cm3/s) than doxorubicin animals (0.066±0.023 cm3/s), PSP±SD, p<0.001. These permeability changes correlated with significant functional changes. There was a significant decline in cardiac function with a deleterious effect of chemotherapy on fractional shortening (p<0.001), left ventricular developed pressure (p<0.001), contractility (p<0.001), and relaxation (p=0.02). Based on our results, cardiac capillary permeability changes can be detected after in vivo chemotherapy treatment using our fluorescent multiple indicator dilution technique, and may provide valuable information in evaluating cardiotoxicity of novel drugs. PMID:25224075
Measurement of the body composition of living gray seals by hydrogen isotope dilution
Reilly, J.J.; Fedak, M.A. )
1990-09-01
The body composition of living gray seals (Halichoerus grypus) can be accurately predicted from a two-step model that involves measurement of total body water (TBW) by {sup 2}H or {sup 3}H dilution and application of predictive relationships between body components and TBW that were derived empirically by slaughter chemical analysis. TBW was overestimated by both {sup 2}HHO and {sup 3}HHO dilution; mean overestimates were 2.8 +/- 0.9% (SE) with 2H and 4.0 +/- 0.6% with {sup 3}H. The relationships for prediction of total body fat (TBF), protein (TBP), gross energy (TBGE), and ash (TBA) were as follows: %TBF = 105.1 - 1.47 (%TBW); %TBP = 0.42 (%TBW) - 4.75; TBGE (MJ) = 40.8 (mass in kg) - 48.5 (TBW in kg) - 0.4; and TBA (kg) = 0.1 - 0.008 (mass in kg) + 0.05 (TBW in kg). These relationships are applicable to gray seals of both sexes over a wide range of age and body conditions, and they predict the body composition of gray seals more accurately than the predictive equations derived from ringed seals (Pusa hispida) and from the equation of Pace and Rathbun, which has been reported to be generally applicable to mammals.
Fan, Fan; Chen, Chun Cheng Andy; Zhang, Jin; Schreck, Carlos M N; Roman, Eric A; Williams, Jan M; Hirata, Takashi; Sharma, Mukut; Beard, Daniel A; Savin, Virginia J; Roman, Richard J
2015-12-15
This study describes a high-throughput fluorescence dilution technique to measure the albumin reflection coefficient (σAlb) of isolated glomeruli. Rats were injected with FITC-dextran 250 (75 mg/kg), and the glomeruli were isolated in a 6% BSA solution. Changes in the fluorescence of the glomerulus due to water influx in response to an imposed oncotic gradient was used to determine σAlb. Adjustment of the albumin concentration of the bath from 6 to 5, 4, 3, and 2% produced a 10, 25, 35, and 50% decrease in the fluorescence of the glomeruli. Pretreatment of glomeruli with protamine sulfate (2 mg/ml) or TGF-β1 (10 ng/ml) decreased σAlb from 1 to 0.54 and 0.48, respectively. Water and solute movement were modeled using Kedem-Katchalsky equations, and the measured responses closely fit the predicted behavior, indicating that loss of albumin by solvent drag or diffusion is negligible compared with the movement of water. We also found that σAlb was reduced by 17% in fawn hooded hypertensive rats, 33% in hypertensive Dahl salt-sensitive (SS) rats, 26% in streptozotocin-treated diabetic Dahl SS rats, and 21% in 6-mo old type II diabetic nephropathy rats relative to control Sprague-Dawley rats. The changes in glomerular permeability to albumin were correlated with the degree of proteinuria in these strains. These findings indicate that the fluorescence dilution technique can be used to measure σAlb in populations of isolated glomeruli and provides a means to assess the development of glomerular injury in hypertensive and diabetic models.
The measurement of extravascular lung water by thermal-green dye indicator dilution.
Lewis, F R; Elings, V B; Hill, S L; Christensen, J M
1982-01-01
The theory and practice of the thermal-dye indicator-dilution method for measurement of EVLW has been discussed, and all available animal data from our laboratory correlating EVTV and gravimetric EVLW have been presented. The method appears to function well over the entire range of edema seen , and to be minimally dependent on cardiac output. Thermal-indicator loss does not seem to be a significant problem and does not impair the accuracy of this method. Out results are consistent with earlier works in the field in identifying significant differences between the isotopic EVLW methods and the thermal-dye method, and it seems likely that these differences are due to the much greater diffusion rate of the thermal indicator.
A stable isotope dilution method for measuring bioavailability of organic contaminants
Delgado-Moreno, Laura; Gan, Jay
2014-01-01
Methods for determining bioavailability of organic contaminants suffer various operational limitations. We explored the use of stable isotope labeled references in developing an isotope dilution method (IDM) to measure the exchangeable pool (E) of pyrene and bifenthrin as an approximation of their bioavailability in sediments. The exchange of deuterated bifenthrin or pyrene with its native counterpart was completed within 48 h. The derived E was 38–82% for pyrene and 28–59% for bifenthrin. Regression between E and the sum of rapid and slow desorption fractions obtained from sequential desorption showed a slope close to 1.0. The ability of IDM to predict bioavailability was further shown from a strong relationship (r2 > 0.93) between E and bioaccumulation into Chironomus tentans. Given the abundance of stable isotope labeled references and their relatively easy analysis, the IDM has the potential to become a readily adoptable tool for estimating organic contaminants bioaccessibility in various matrices. PMID:23434573
NASA Astrophysics Data System (ADS)
Fussen, D.; Tetard, C.; Dekemper, E.; Pieroux, D.; Mateshvili, N.; Vanhellemont, F.; Franssens, G.; Demoulin, P.
2015-08-01
In this paper, we consider occultations of celestial bodies through the atmospheric limb from low Earth orbit satellites and we show how the usual change of tangent altitude associated with atmospheric refraction is inseparably connected to a variation of the observed apparent intensity, for extended and pointlike sources. We demonstrate, in the regime of weak refraction angles, that atmospheric optical dilution and image deformation are strictly concomitant. The approach leads to the integration of a simple differential equation related to the observed transmittance in the absence of other absorbing molecules along the optical path. The algorithm does not rely on the absolute knowledge of the radiometer pointing angle that is related to the accurate knowledge of the satellite attitude. We successfully applied the proposed method to the measurements performed by two past occultation experiments: GOMOS for stellar and ORA for solar occultations. The developed algorithm (named ARID) will be applied to the imaging of solar occultations in a forthcoming pico-satellite mission.
NASA Astrophysics Data System (ADS)
Fussen, D.; Tétard, C.; Dekemper, E.; Pieroux, D.; Mateshvili, N.; Vanhellemont, F.; Franssens, G.; Demoulin, P.
2015-04-01
In this paper, we show how the usual change of tangent altitude associated with atmospheric refraction is inseparably connected to a variation of the observed apparent intensity, for extended and pointlike sources. We demonstrate, in the regime of weak refraction angles, that atmospheric optical dilution and image deformation are strictly concomitant. The approach leads to the integration of a simple differential equation related to the observed transmittance in the absence of other absorbing molecules along the optical path. We successfully applied the proposed method to the measurements performed by two past occultation experiments: GOMOS for stellar and ORA for solar occultations. The developed algorithm (named ARID) will be applied to the imaging of solar occultations in a forthcoming pico-satellite mission.
Berry Yelverton, T.L.; Roberts, W.L.
2008-10-15
Soot surface temperature was measured in laminar jet diffusion flames at atmospheric and elevated pressures. The soot surface temperature was measured in flames at one, two, four, and eight atmospheres with both pure and diluted (using helium, argon, nitrogen, or carbon dioxide individually) ethylene fuels with a calibrated two-color soot pyrometry technique. These two dimensional temperature profiles of the soot aid in the analysis and understanding of soot production, leading to possible methods for reducing soot emission. Each flame investigated was at its smoke point, i.e., at the fuel flow rate where the overall soot production and oxidation rates are equal. The smoke point was chosen because it was desirable to have similar soot loadings for each flame. A second set of measurements were also taken where the fuel flow rate was held constant to compare with earlier work. These measurements show that overall flame temperature decreases with increasing pressure, with increasing pressure the position of peak temperature shifts to the tip of the flame, and the temperatures measured were approximately 10% lower than those calculated assuming equilibrium and neglecting radiation. (author)
Influence of probe sampling on reacting species measurement in diluted combustion
Lupant, D.; Pesenti, B.; Lybaert, P.
2010-07-15
In-flame measurements of temperature and major species are realized with intrusive probes in a laboratory scale furnace working in diluted combustion. The shape and the position of the reaction zone are experimentally identified from the distribution of temperature and carbon monoxide in a particular symmetry plane. For this purpose, two probes were designed: the sampling probe, to measure species content of the gas sample and the suction pyrometer, for the temperature. The first is completely cooled to quench the reaction, but the second is just partly cooled for handling. However, as both probes take gas sample, the species content is available in either case. Consequently the suction pyrometer can be used to measure simultaneously temperature and species, reducing by half the length of the experimental campaign. Comparing species contents on a non-reactive mixture, it has been observed that the spatial averaging is the same with both probes. The perturbation of the flow is assessed thanks to a CFD modeling of the furnace including the probe. Even if it is significant - the differences between the computed values and the measurements are about 3-4 times the measurement error - the position and the value of the maximum is well captured as well as the opening of the jet. However, the species contents measured within a reactive mixture differ significantly. For a stable regime, the levels and the distribution of CO are similar with both probes, but the gradients at the border of the reaction zone are sharper with the suction pyrometer. For another regime, for which the reaction zone is lifted and less stable, the fields of species are completely different following the probe used. A chemical kinetic modeling has shown that the reaction inside the non-cooled part of the suction pyrometer is promoted when it is placed in particular region. The use of the suction pyrometer as sampling probe inside a reaction zone should therefore be avoided even in diluted combustion
McGlasson, David L; Fritsma, George A
2016-01-01
The dabigatran dose-response is predictable; however, it is necessary to measure plasma levels in a variety of clinical conditions. We evaluated a novel dabigatran measure - the 'dilute Russell viper venom confirm (DRVVC) assay' - against current developmental assays and a reference method. We measured plasma dabigatran and compared results from the Stago Sta-Clot DRVVC assay, Stago Ecarin Chromogenic Assay, Biophen Hemoclot Thrombin Inhibitor, and liquid chromatography tandem mass spectrometry. We obtained dabigatran calibrators and controls from Biophen, and performed the coagulation assays using a Stago STA-R Evolution coagulometer. Liquid chromatography tandem mass spectrometry method specimens were performed on an AB Sciex instrument at LabCorp. We enrolled 97 anticoagulation clinic patients (mean age 76 years) who were taking 150 mg dabigatran twice daily. All had creatinine clearances above 30 ml/min; patients were not excluded for concurrent medications or health issues. Citrated blood specimens were processed immediately, and stored at -70°C. We did not correlate collection time with medication time. We employed descriptive statistics, analysis of variance, and the Bland-Altman difference plot to assess the data. The range for all assays was 11.6-917 ng/ml. Analysis of variance generated a P value of 0.1 and Bland-Altman differences were all below 4.0% compared with DRVVC. The DRVVC measures dabigatran with validity comparable to other methods.
Validity of deuterium oxide dilution for the measurement of body fat among Singaporeans.
Deurenberg-Yap, Mabel; Deurenberg, Paul
2002-09-01
Body fat percent (BF%) was measured in 108 adult Chinese, 76 Malays, and 107 Indians in Singapore by densitometry, deuterium oxide dilution (hydrometry), dual energy x-ray absorptiometry (DXA) and a chemical four-compartment model (BF%4c). The hydration of the fat-free mass (FFM) was calculated. Subjects ranged in age from 18 to 69 years and their body mass index ranged from 16 to 40 kg/m2. BF%4c for the various subgroups were: Chinese females (33.5 +/- 7.5%), Chinese males (24.4 +/- 6.1%), Malay females (37.8 +/- 6.3%), Malay males (26.0 +/- 7.6%), Indian females (38.2 +/- 7.0%) and Indian males (28.1 +/- 5.5%). Biases were found between BF%4c and BF% measured by 2-compartment models (hydrometry, densitometry, DXA), with systematic underestimation by DXA and densitometry. On a group level hydrometry had the lowest bias while DXA gave the highest bias. When validated against BF%4c, 2-compartment models were found to be unsuitable for accurate measures of body fat due to high biases at the individual level and the violation of assumptions of constant hydration of FFM and density FFM among the ethnic groups. On a group level the best 2-compartment model for measuring body fat was found to be hydrometry. PMID:12362808
Image-based correction of the light dilution effect for SO2 camera measurements
NASA Astrophysics Data System (ADS)
Campion, Robin; Delgado-Granados, Hugo; Mori, Toshiya
2015-07-01
Ultraviolet SO2 cameras are increasingly used in volcanology because of their ability to remotely measure the 2D distribution of SO2 in volcanic plumes, at a high frequency. However, light dilution, i.e., the scattering of ambient photons within the instrument's field of view (FoV) on air parcels located between the plume and the instrument, induces a systematic underestimation of the measurements, whose magnitude increases with distance, SO2 content, atmospheric pressure and turbidity. Here we describe a robust and straightforward method to quantify and correct this effect. We retrieve atmospheric scattering coefficients based on the contrast attenuation between the sky and the increasingly distant slope of the volcanic edifice. We illustrate our method with a case study at Etna volcano, where difference between corrected and uncorrected emission rates amounts to 40% to 80%, and investigate the temporal variations of the scattering coefficient during 1 h of measurements on Etna. We validate the correction method at Popocatépetl volcano by performing measurements of the same plume at different distances from the volcano. Finally, we reported the atmospheric scattering coefficients for several volcanoes at different latitudes and altitudes.
Swart, D J; Simeonsson, J B
1999-11-01
A procedure for the direct determination of arsenic in diluted serum by electrothermal atomization laser-excited atomic fluorescence spectrometry (ETA-LEAFS) is reported. Laser radiation needed to excite As at 193.696 and 197.197 nm is generated as the second anti-Stokes stimulated Raman scattering output of a frequency-doubled dye laser operating near 230.5 and 235.5 nm, respectively. Two different LEAFS schemes have been utilized and provide limits of detection of 200-300 fg for As in aqueous standards. When measurements of serum samples diluted 1:10 with deionized water are performed, a stable background signal is observed that can be accounted for by taking measurements with the laser tuned off-wavelength. No As is detected in any of the bovine or human serum samples analyzed. Measurements of 100 pg/mL standard additions of As to a diluted bovine serum sample utilizing either inorganic or organic As species demonstrate a linear relationship of the fluorescence signal to As spike concentration, but exhibit a sensitivity of approximately half that observed in pure aqueous standards. The limit of detection for As in 1:10 diluted serum samples is 65 pg/mL or 650 fg absolute mass, which corresponds to 0.65 ng/mL As in undiluted serum. To our knowledge, the ETA-LEAFS procedure is currently the only one capable of directly measuring As in diluted serum at these levels.
Chew, Gina; Walczyk, Thomas
2013-04-01
Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.
NASA Technical Reports Server (NTRS)
Soller, Babs R.; Favreau, Janice; Idwasi, Patrick O.
2003-01-01
The feasibility of using near-infrared (NIR) spectroscopy in combination with partial least-squares (PLS) regression was explored to measure electrolyte concentration in whole blood samples. Spectra were collected from diluted blood samples containing randomized, clinically relevant concentrations of Na+, K+, and Ca2+. Sodium was also studied in lysed blood. Reference measurements were made from the same samples using a standard clinical chemistry instrument. Partial least squares (PLS) was used to develop calibration models for each ion with acceptable results (Na+, R2 = 0.86, CVSEP = 9.5 mmol/L; K+, R2 = 0.54, CVSEP = 1.4 mmol/L; Ca2+, R2 = 0.56, CVSEP = 0.18 mmol/L). Slightly improved results were obtained using a narrower wavelength region (470-925 nm) where hemoglobin, but not water, absorbed indicating that ionic interaction with hemoglobin is as effective as water in causing measurable spectral variation. Good models were also achieved for sodium in lysed blood, illustrating that cell swelling, which is correlated with sodium concentration, is not required for calibration model development.
Adolfsson-Erici, Margaretha; Åkerman, Gun; McLachlan, Michael S
2012-08-01
Modern chemical legislation requires measuring the bioconcentration factor (BCF) of large numbers of chemicals in fish. The BCF must be corrected for growth dilution, because fish growth rates vary between laboratories. Two hypotheses were tested: (1) that BCFs of multiple chemicals can be measured simultaneously in one experiment, and (2) that internal benchmarking using a conservative test substance in the chemical mixture can be used to correct for growth dilution. Bioconcentration experiments were conducted following major elements of the OECD 305 guideline. Fish were simultaneously exposed to 11 chemicals selected to cover a range of BCFs and susceptibility to biotransformation. A method was developed to calculate the growth-corrected elimination rate constant from the concentration ratio of the analyte and a benchmarking chemical for which growth dilution dominated other elimination mechanisms. This method was applied to the experimental data using hexachlorobenzene as the benchmarking chemical. The growth dilution correction lowered the apparent elimination rate constants by between 5% and a factor of four for eight chemicals, while for two chemicals the growth-corrected elimination rate constant was not significantly different from zero. The benchmarking method reduced the uncertainty in the elimination rate constant compared to the existing method for growth dilution correction. The BCFs from exposing fish to 10 chemicals at once were consistent with BCF values from single-chemical exposures from the literature, supporting hypothesis 1.
Indicator dilution measurements of lung volumes and alveolar air exchange during breathing.
Hechtman, H B; Reid, M H; Dorn, B C; Weisel, R D
1973-05-01
A new triple tracer indicator dilution technique has been used to measure alveolar ventilation as well as air and tissue volumes in the lungs of experimental animals and man. The tracers indocyanine green, [(121)I]antipyrine and xenon-133 were rapidly injected into the right atrium, while sampling was carried out from a peripheral artery. Blood flow and tissue volumes were obtained by classical analysis of the indocyanine green and antipyrine concentration-time curves. A double exit-port, constant air flow model was used to analyze the xenon curves, because ventilatory loss led to incomplete recovery of the gas tracer in effluent blood. Uniform ventilation and perfusion were assumed. This analysis permitted calculation of alveolar ventilation (VA(Xe)) and functional residual capacity (FRC(Xe)) during normal breathing. In control studies, VA(Xe) was similar to VA(co2), obtained with the steady-state CO(2) method (r = 0.87), while in critically ill patients the xenon measurement was significantly lower, averaging 54% of VA(co2). In theory, underestimates in VA(Xe) and decrease in the ratio VA(Xe)/VA(co2) relate to nonuniformity in regional ventilation and perfusion. The effect is greatest for the slightly soluble gas, xenon. The significant inverse correlation between VA(Xe)/VA(co2) and the physiologic shunt is consistent with this postulate.FRC(Xe) was similar to the predicted FRC in animals but was 76% of the helium measured FRC in patients. FRC(Xe) was significantly lower than the xenon measured air volumes during breath-holding when nonuniformity of ventilation was not operative. Lung tissue volumes in animals were 83% of gravimetric lung weights, while in patients the volumes were much lower than predicted. Nonhomogeneous lung function, including failure to perfuse the entire capillary bed, with resultant incomplete penetration of tracers into all segments of lung air and tissue, may explain these findings. The resultant errors can be significant in sick
Agnew, R E; Yan, T; McCaughey, W J; McEvoy, J D; Patterson, D C; Porter, M G; Steen, R W J
2005-07-01
The objective of the present study was to investigate the potential of the urea dilution technique, coupled with live animal measures to predict the body components of dairy cattle. The study involved 104 lactating Holstein-Friesian cows offered grass silage-based diets. Urea space volume (USV) was calculated from 2 collection periods of blood samples following infusion of urea at 12 (USV12, kg) and 30 (USV30, kg) min after infusion, and then as a proportion of live weight (LW) or empty body weight (EBW). All cows were slaughtered within 2 d of the USV trials. Large ranges existed in EBW and empty body concentrations of water, crude protein (CP), lipid, ash, and gross energy (GE). The USV12 and USV30 were both positively related to LW, EBW, and empty body component weights. The r2 values for USV12 were greater than USV30. The r2 values in the relationships of EBW and empty body composition with USV, however, were smaller than those with LW. Nevertheless, the relationships were improved when both USV and LW were used as predictors, rather than using either alone. Adding milk yield and body condition score as supporting predictors to prediction equations using USV and LW data for EBW, lipid, and GE contents further improved the relationships (r2 = 0.93, 0.66, and 0.77, respectively). Internal evaluation of one-third of the present data using equations developed from two-thirds of the present data indicated that using USV, live weight, and other live animal variables as predictors, rather than using USV alone, considerably improved the prediction accuracy. It was concluded that USV can be used to predict body composition, but the relationships with USV were poorer than those with LW. The USV can only be used as a supporting variable to live weight for prediction of body components in lactating dairy cows.
Measurement of solute transport in the endothelial glycocalyx using indicator dilution techniques.
Gao, Lujia; Lipowsky, Herbert H
2009-09-01
A new method is presented to quantify changes in permeability of the endothelial glycocalyx to small solutes and fluid flow using techniques of indicator dilution. Following infusion of a bolus of fluorescent solutes (either FITC or FITC conjugated Dextran70) into the rat mesenteric circulation, its transient dispersion through post-capillary venules was recorded and analyzed offline. To represent dispersion of solute as a function of radial position in a microvessel, a virtual transit time (VTT) was calculated from the first moment of fluorescence intensity-time curves. Computer simulations and subsequent in vivo measurements showed that the radial gradient of VTT within the glycocalyx layer (Delta VTT/Delta r) may be related to the hydraulic resistance within the layer along the axial direction in a post-capillary venule and the effective diffusion coefficient within the glycocalyx. Modeling the inflammatory process by superfusion of the mesentery with 10(-7) M fMLP, Delta VTT/Delta r was found to decrease significantly from 0.23 +/- 0.08 SD s/microm to 0.18 +/- 0.09 SD s/microm. Computer simulations demonstrated that Delta VTT/Delta r is principally determined by three independent variables: glycocalyx thickness (delta), hydraulic resistivity (K(r)) and effective diffusion coefficient of the solute (D(eff)) within the glycocalyx. Based upon these simulations, the measured 20% decrease in Delta VTT/Delta r at the endothelial cell surface corresponds to a 20% increase in D(eff) over a broad range in K(r), assuming a constant thickness delta. The absolute magnitude of D(eff) required to match Delta VTT/Delta r between in vivo measurements and simulations was found to be on the order of 2.5 x 10(-3) x D(free), where D(free) is the diffusion coefficient of FITC in aqueous media. Thus the present method may provide a useful tool for elucidating structural and molecular alterations in the glycocalyx as occur with ischemia, metabolic and inflammatory events.
Assay dilution factors confound measures of total antioxidant capacity in polyphenol-rich juices
Technology Transfer Automated Retrieval System (TEKTRAN)
The extent to which sample dilution factor (DF) affects Total Antioxidant Capacity (TAC) values is poorly understood. Thus, we examined the impact of DF on the ORAC, FRAP, DPPH, and Total Phenols (TP) assays using pomegranate juice (PJ), grape juice (GJ), selected flavonoids, ascorbic acid, and ella...
Martineau, Charlotte; Fayon, Franck; Legein, Christophe; Buzaré, Jean-Yves; Silly, Gilles; Massiot, Dominique
2007-07-14
A new solid-state MAS NMR experiment is proposed to accurately measure heteronuclear (19)F-(207)Pb J-coupling constants, even though these couplings are not visible on high speed (19)F 1D MAS spectra; in particular, we demonstrate that the J-resolved experiment combined with scalar multiple-quantum filtering considerably improves the resolution of J-multiplet patterns for dilute spin systems. PMID:17594032
Hamilton, W.A.; Butler, P.D.; Hayter, J.B.; Magid, L.J.; Kreke, P.J.
1995-06-24
Although the behavior of a fluid under shear near a surface can be expected to be critically important to its drag and lubrication properties, most shear measurements to date have been of the bulk. This paper outlines the use of a specially developed Poiseuille shear cell at grazing incidence to measure the small-angle neutron scattering (SANS) signal from the first few tens of microns in the interfacial region. The authors illustrate the technique with measurements made on the near-surface ordering in flow past a quartz surface of dilute surfactant solutions comprising highly extended self-assembling ``threadlike`` micelles.
Instrumental measurements of different homeopathic dilutions of potassium iodide in water.
Jerman, I; Berden, M; Skarja, M
1999-01-01
Although more than 200 years have elapsed since the beginning of homeopathy and in spite of numerous confirmatory scientific experiments, the so-called memory of water is still a highly disputable and controversial theme in scientific circles. To make a contribution to solving this riddle, our research group tried to examine memory properties of water by the method of differential corona discharge Kirlian electrophotography of water-drop pairs. The method is based on a modified form of Kirlian photography with a subsequent thorough computer picture analysis. The potassium iodide (KI) mother solution (0.1M) was diluted in the standard way (without potentisation) or with potentisation (succussion by hand - by striking the vial 60 times against a large book as used traditionally) to 10(-3)M, 10(-6)M, 10(-10)M, 10(-16)M, 10(-17)M and 10(-24)M KI solutions. In the electrophotography method a drop of KI solution was compared with a drop of control water. To get a dependable system of results we compared homeopathic dilutions with ordinary distilled water, sham-potentised distilled water and non-potentised (standard) solutions. The results were analyzed by the Chi-square Goodness-of-fit test and the Sign test. They showed repeatable and statistically significant effects of concentration of KI dilutions as well as potentisation on the corona discharge process (from p < 0.05 to p < 0.001). This indicates that there is some physical basis of molecular (ionic) information imprinted into water. PMID:10472820
Fu, Riqiang; Li, Jun; Cui, Jingyu; Peng, Xinhua
2016-07-01
Numerous nuclear magnetic resonance (NMR) measurements of spin-lattice relaxation times (T1S) for dilute spins such as (13)C have led to investigations of the motional dynamics of individual functional groups in solid materials. In this work, we revisit the Solomon equations and analyze how the heteronuclear cross relaxation between the dilute S (e.g. (13)C) and abundant I (e.g. (1)H) spins affects the measured T1S values in solid-state NMR in the absence of (1)H saturation during the recovery time. It is found theoretically that at the beginning of the S spin magnetization recovery, the existence of non-equilibrium I magnetization introduces the heteronuclear cross relaxation effect onto the recovery of the S spin magnetization and confirmed experimentally that such a heteronuclear cross relaxation effect results in the recovery overshoot phenomena for the dilute spins when T1S is on the same order of T1H, leading to inaccurate measurements of the T1S values. Even when T1S is ten times larger than T1H, the heteronuclear cross relaxation effect on the measured T1S values is still noticeable. Furthermore, this cross relaxation effect on recovery trajectory of the S spins can be manipulated and even suppressed by preparing the initial I and S magnetization, so as to obtain the accurate T1S values. A sample of natural abundance l-isoleucine powder has been used to demonstrate the T1S measurements and their corresponding measured T1C values under various experimental conditions. PMID:27187211
Fu, Riqiang; Li, Jun; Cui, Jingyu; Peng, Xinhua
2016-07-01
Numerous nuclear magnetic resonance (NMR) measurements of spin-lattice relaxation times (T1S) for dilute spins such as (13)C have led to investigations of the motional dynamics of individual functional groups in solid materials. In this work, we revisit the Solomon equations and analyze how the heteronuclear cross relaxation between the dilute S (e.g. (13)C) and abundant I (e.g. (1)H) spins affects the measured T1S values in solid-state NMR in the absence of (1)H saturation during the recovery time. It is found theoretically that at the beginning of the S spin magnetization recovery, the existence of non-equilibrium I magnetization introduces the heteronuclear cross relaxation effect onto the recovery of the S spin magnetization and confirmed experimentally that such a heteronuclear cross relaxation effect results in the recovery overshoot phenomena for the dilute spins when T1S is on the same order of T1H, leading to inaccurate measurements of the T1S values. Even when T1S is ten times larger than T1H, the heteronuclear cross relaxation effect on the measured T1S values is still noticeable. Furthermore, this cross relaxation effect on recovery trajectory of the S spins can be manipulated and even suppressed by preparing the initial I and S magnetization, so as to obtain the accurate T1S values. A sample of natural abundance l-isoleucine powder has been used to demonstrate the T1S measurements and their corresponding measured T1C values under various experimental conditions.
NASA Astrophysics Data System (ADS)
Fu, Riqiang; Li, Jun; Cui, Jingyu; Peng, Xinhua
2016-07-01
Numerous nuclear magnetic resonance (NMR) measurements of spin-lattice relaxation times (T1S) for dilute spins such as 13C have led to investigations of the motional dynamics of individual functional groups in solid materials. In this work, we revisit the Solomon equations and analyze how the heteronuclear cross relaxation between the dilute S (e.g. 13C) and abundant I (e.g. 1H) spins affects the measured T1S values in solid-state NMR in the absence of 1H saturation during the recovery time. It is found theoretically that at the beginning of the S spin magnetization recovery, the existence of non-equilibrium I magnetization introduces the heteronuclear cross relaxation effect onto the recovery of the S spin magnetization and confirmed experimentally that such a heteronuclear cross relaxation effect results in the recovery overshoot phenomena for the dilute spins when T1S is on the same order of T1H, leading to inaccurate measurements of the T1S values. Even when T1S is ten times larger than T1H, the heteronuclear cross relaxation effect on the measured T1S values is still noticeable. Furthermore, this cross relaxation effect on recovery trajectory of the S spins can be manipulated and even suppressed by preparing the initial I and S magnetization, so as to obtain the accurate T1S values. A sample of natural abundance L-isoleucine powder has been used to demonstrate the T1S measurements and their corresponding measured T1C values under various experimental conditions.
Peng, Liying; Jiang, Dandan; Wang, Zhenxin; Liu, Jiwei; Li, Haiyang
2016-01-01
Exhaled nitric oxide (NO) is one of the most promising breath markers for respiratory diseases. Its profile for exhalation and the respiratory NO production sites can provide useful information for medical disease diagnosis and therapeutic procedures. However, the high-level moisture in exhaled gas always leads to the poor selectivity and sensitivity for ion spectrometric techniques. Herein, a method based on fast non-equilibrium dilution ion mobility spectrometry (NED-IMS) was firstly proposed to directly monitor the exhaled NO profile on line. The moisture interference was eliminated by turbulently diluting the original moisture to 21% of the original with the drift gas and dilution gas. Weak enhancement was observed for humid NO response and its limit of detection at 100% relative humidity was down to 0.58 ppb. The NO concentrations at multiple exhalation flow rates were measured, while its respiratory production sites were determined by using two-compartment model (2CM) and Högman and Meriläinen algorithm (HMA). Last but not the least, the NO production sites were analyzed hourly to tentatively investigate the daily physiological process of NO. The results demonstrated the capacity of NED-IMS in the real-time analysis of exhaled NO and its production sites for clinical diagnosis and assessment. PMID:26975333
Assay Dilution Factors Confound Measures of Total Antioxidant Capacity in Polyphenol-Rich Juices
Bolling, Bradley W.; Chen, Ya-Yen; Kamil, Alison G.; Chen, C-Y. Oliver
2016-01-01
The extent to which sample dilution factor (DF) affects total antioxidant capacity (TAC) values is poorly understood. Thus, we examined the impact of DF on the ORAC, FRAP, DPPH, and total phenols (TP) assays using pomegranate juice (PJ), grape juice (GJ), selected flavonoids, ascorbic acid, and ellagic acid. For ORAC, GJ was comparable to PJ at DF 750, but at DF 2000, the ORAC value of GJ was 40% more than PJ. Increasing DF increased GJ and PJ, DPPH, TP, and FRAP values 11% and 14%, respectively. Increased test concentrations of quercetin and catechin resulted in 51% and 126% greater ORAC values, but decreased naringenin by 68%. Flavonoids, but not ellagic acid or ascorbic acid, may contribute to the dilution effect on the variation of final TAC values. Thus, reporting TAC or TP using a single DF may introduce uncertainty about the confidence of TAC assay values, especially when comparing different juices. These results underscore the importance of using compatible test standards for reporting TAC values. PMID:22251245
Unification and Infinite Series
ERIC Educational Resources Information Center
Leyendekkers, J. V.; Shannon, A. G.
2008-01-01
Some infinite series are analysed on the basis of the hypergeometric function and integer structure and modular rings. The resulting generalized functions are compared with differentiation of the "mother" series. (Contains 1 table.)
Acoustoelastic constants in dilute two-phase alloys
NASA Technical Reports Server (NTRS)
Salama, K.; Schneider, E.; Chu, S. L.
1986-01-01
Acoustoelastic constants are calculated for two-phase alloys containing dilute concentrations of precipitates in a solid-solution matrix, on the basis of a model in which the precipitates are represented as a dilute elastic suspension of spherical particle inclusions in an infinite matrix. The longitudinal propagation velocity in the alloy is thereby obtained in terms of the precipitates' concentration and the elastic moduli of the two phases. Results are presented which indicate that the acoustoelastic constant of longitudinal waves in a dilute two-phase alloy varies linearly with the concentration of second-phase precipitates, in agreement with recent measurements in aluminum and steel alloys where the acoustoelastic constants changed linearly with the second phase's volume fraction.
Haldimann, M; Eastgate, A; Zimmerli, B
2000-11-01
A new ICP-MS method for the determination of iodine in food samples is presented. The method makes use of a new miniature cyclonic spray chamber and a concentric glass nebulizer that is designed for low sample uptakes and is operated in a self-aspirating mode. As a consequence the wash-out was accelerated over conventional systems. This configuration allows the direct determination of iodine in mineralized solutions following digestion with nitric acid only. No strong oxidizing reagents such as perchloric acid or lengthy sample preparation were necessary to alter the chemical form of potentially volatile species. The isotope dilution technique using the long-lived isotope 129I was applied to obtain freedom from matrix effects. The present study reports on results for total iodine in selected nutritional and biological reference materials and makes a comparison with instrumental neutron activation analysis.
NASA Astrophysics Data System (ADS)
Mudra, R.; Muroi, C.; Niederer, P.; Keller, E.
2008-09-01
The cerebral blood flow (CBF) is an important vital parameter in neurointensive care. Currently, there is no non-invasive method for its measurement that can easily be applied at the bedside. A new tool to determine CBF is based on near-infrared spectroscopy (NIRS) applied together with indocyanine green (ICG) dye dilution. From a bilateral measurement on selected regions on the head of infrared (IR) absorption at various wavelengths during the dilution maneuver, the vascular perfusion characteristics of the two brain hemispheres can be determined in terms of mean transit time (mtt) of ICG, cerebral blood volume (CBV) and CBF. So far, on nine healthy volunteers, NIRS ICG dye dilution bihemispheric measurements were performed, which yielded to mtt given as median (range) of 9.3 s (5.1-16.3 s), CBV of 3.5 ml/100 g (1.7-4.1 ml/100 g), and CBF of 18.2 ml/(100 g×min) [11.1-48.6 ml/(100 g×min)]. Additionally, the blood flow index (BFI) was calculated with BFI= 13.8 mg/(100 g×s) [6.6-15.2 mg/(100 g×s)]. The Spearman rank correlation coefficient between CBF and BFI was RS = 0.76. However, as the Bland & Altman plot between CBFNIRS and the CBFBFI documents, the limits of agreement are rather wide (21.9±6.7). Under physiological conditions in healthy volunteers, no differences could be detected between the hemispheres.
NASA Technical Reports Server (NTRS)
Hearn, C. P.; Bailey, M. C.; Czerner, M. J.; Dudley, K. L.; Vedeler, E.
1990-01-01
The feasibility of a continuous-wave, distance-measuring technique for measuring the distance from a spacecraft antenna to a highly ionized plasma surface is examined. The reflection coefficient angle is computed for several aperture models. It is concluded that aperture size and the presence of a nonablating dielectric cover over the antenna are critical factors.
Learning to See the Infinite: Measuring Visual Literacy Skills in a 1st-Year Seminar Course
ERIC Educational Resources Information Center
Palmer, Michael S.; Matthews, Tatiana
2015-01-01
Visual literacy was a stated learning objective for the fall 2009 iteration of a first-year seminar course. To help students develop visual literacy skills, they received formal instruction throughout the semester and completed a series of carefully designed learning activities. The effects of these interventions were measured using a one-group…
Kim, Mi Eon; Kim, Yong Doo; Kang, Ji Hwan; Heo, Gwi Suk; Lee, Dong Soo; Lee, Sangil
2016-04-01
Dimethyl sulphide (DMS) is an important compound in global atmospheric chemistry and climate change. Traceable international standards are essential for measuring accurately the long-term global trend in ambient DMS. However, developing accurate gas standards for sub-nanomole per mole (nmol/mol) mole fractions of DMS in a cylinder is challenging, because DMS is reactive and unstable. In this study, a dynamic dilution method that is traceable and precise was developed to generate sub-nmol/mol DMS gas mixtures with a dynamic dilution system based on sonic nozzles and a long-term (>5 years) stable 10 μmol/mol parent DMS primary standard gas mixtures (PSMs). The dynamic dilution system was calibrated with traceable methane PSMs, and its estimated dilution factors were used to calculate the mole fractions of the dynamically generated DMS gas mixtures. A dynamically generated DMS gas mixture and a 6 nmol/mol DMS PSM were analysed against each other by gas chromatography with flame-ionisation detection (GC/FID) to evaluate the dilution system. The mole fractions of the dynamically generated DMS gas mixture determined against a DMS PSM and calculated with the dilution factor agreed within 1% at 6 nmol/mol. In addition, the dynamically generated DMS gas mixtures at various mole fractions between 0.4 and 11.7 nmol/mol were analysed by GC/FID and evaluated for their linearity. The analytically determined mole fractions showed good linearity with the mole fractions calculated with the dilution factors. Results showed that the dynamic dilution method generates DMS gas mixtures ranging between 0.4 nmol/mol and 12 nmol/mol with relative expanded uncertainties of less than 2%. Therefore, the newly developed dynamic dilution method is a promising reference method for generating sub-nmol/mol DMS gas standards for accurate ambient measurements.
Grieshop, Andrew P; Miracolo, Marissa A; Donahue, Niel M; Robinson, Allen L
2009-07-01
The gas-particle partitioning of primary organic aerosol (POA) emissions from a diesel engine and the combustion of hard- and soft-woods in a stove was investigated by isothermally diluting them in a smog chamber or by passing them through a thermodenuder and measuring the extent of evaporation. The experiments were conducted at atmospherically relevant conditions: low concentrations and small temperature perturbations. The partitioning of the POA emissions from both sources varied continuously with changing concentration and temperature. Although the POA emissions are semivolatile, they do not completely evaporate at typical atmospheric conditions. The overall partitioning characteristics of diesel and wood smoke POA are similar, with wood smoke being somewhat less volatile than the diesel exhaust. The gas-particle partitioning of aerosols formed from flash-vaporized engine lubricating oil was also studied; diesel POA is somewhat more volatile than the oil aerosol. The experimental data from the dilution- and thermodenuder-based techniques were fit using absorptive partitioning theory to derive a volatility distribution of the POA emissions from each source. These distributions are suitable for use in chemical transport models that simulate POA concentrations.
ERIC Educational Resources Information Center
Wanko, Jeffrey J.
2009-01-01
This article provides a historical context for the debate between Georg Cantor and Leopold Kronecker regarding the cardinality of different infinities and incorporates the short story "Welcome to the Hotel Infinity," which uses the analogy of a hotel with an infinite number of rooms to help explain this concept. Wanko makes use of this history and…
Jamin, P; Goderniaux, P; Bour, O; Le Borgne, T; Englert, A; Longuevergne, L; Brouyère, S
2015-11-01
Measurement of groundwater fluxes is the basis of all hydrogeological study, from hydraulic characterization to the most advanced reactive transport modeling. Usual groundwater flux estimation with Darcy's law may lead to cumulated errors on spatial variability, especially in fractured aquifers where local direct measurement of groundwater fluxes becomes necessary. In the present study, both classical point dilution method (PDM) and finite volume point dilution method (FVPDM) are compared on the fractured crystalline aquifer of Ploemeur, France. The manipulation includes the first use of the FVPDM in a fractured aquifer using a double packer. This configuration limits the vertical extent of the tested zone to target a precise fracture zone of the aquifer. The result of this experiment is a continuous monitoring of groundwater fluxes that lasted for more than 4 days. Measurements of groundwater flow rate in the fracture (Q(t)) by PDM provide good estimates only if the mixing volume (V(w)) (volume of water in which the tracer is mixed) is precisely known. Conversely, the FVPDM allows for an independent estimation of V(w) and Q(t), leading to better precision in case of complex experimental setup such as the one used. The precision of a PDM does not rely on the duration of the experiment while a FVPDM may require long experimental duration to guarantees a good precision. Classical PDM should then be used for rapid estimation of groundwater flux using simple experimental setup. On the other hand, the FVPDM is a more precise method that has a great potential for development but may require longer duration experiment to achieve a good precision if the groundwater fluxes investigated are low and/or the mixing volume is large. PMID:26519822
Jamin, P; Goderniaux, P; Bour, O; Le Borgne, T; Englert, A; Longuevergne, L; Brouyère, S
2015-11-01
Measurement of groundwater fluxes is the basis of all hydrogeological study, from hydraulic characterization to the most advanced reactive transport modeling. Usual groundwater flux estimation with Darcy's law may lead to cumulated errors on spatial variability, especially in fractured aquifers where local direct measurement of groundwater fluxes becomes necessary. In the present study, both classical point dilution method (PDM) and finite volume point dilution method (FVPDM) are compared on the fractured crystalline aquifer of Ploemeur, France. The manipulation includes the first use of the FVPDM in a fractured aquifer using a double packer. This configuration limits the vertical extent of the tested zone to target a precise fracture zone of the aquifer. The result of this experiment is a continuous monitoring of groundwater fluxes that lasted for more than 4 days. Measurements of groundwater flow rate in the fracture (Q(t)) by PDM provide good estimates only if the mixing volume (V(w)) (volume of water in which the tracer is mixed) is precisely known. Conversely, the FVPDM allows for an independent estimation of V(w) and Q(t), leading to better precision in case of complex experimental setup such as the one used. The precision of a PDM does not rely on the duration of the experiment while a FVPDM may require long experimental duration to guarantees a good precision. Classical PDM should then be used for rapid estimation of groundwater flux using simple experimental setup. On the other hand, the FVPDM is a more precise method that has a great potential for development but may require longer duration experiment to achieve a good precision if the groundwater fluxes investigated are low and/or the mixing volume is large.
Pérez, José J; Williams, Megan K; Weerasekera, Gayanga; Smith, Kimberly; Whyatt, Robin M; Needham, Larry L; Barr, Dana Boyd
2010-10-01
We have developed a gas chromatography-high resolution mass spectrometry method for measuring pyrethroid, organophosphorus, carbamate and fipronil pesticides and the synergist piperonyl butoxide in human plasma. Plasma samples were extracted using solid phase extraction and were then concentrated for injection and analysis using isotope dilution gas chromatography-high resolution mass spectrometry. The limits of detection ranged from 10 to 158 pg/mL with relative recoveries at concentrations near the LODs (e.g., 25 or 250 pg/mL) ranging from 87% to 156% (9 of the 16 compounds were within ±15% of 100%). The extraction recoveries ranged from 20% to 98% and the overall method relative standard deviations were typically less than 20% with some exceptions. Analytical characteristics were determined at 25, 250, and 1000 pg/mL.
NASA Astrophysics Data System (ADS)
Korb, H.; Hoeft, A.; Hellige, G.
1984-10-01
Previous studies have shown that intramyocardial blood volume does not vary to a major extent even during extreme variation of hemodynamics and coronary vascular tone. Based on a constant intramyocardial blood volume it is therefore possible to calculate tissue blood flow from the mean transit time of an intravascular tracer. The purpose of this study was to develop a clinically applicable method for measurement of coronary blood flow. The new method was based on indocyanine green, a dye which is bound to albumin and intravasally detectable by means of a fiberoptic catheter device. One fiberoptic catheter was placed in the aortic root and another in the coronary sinus. After central venous dye injection the resulting arterial and coronary venous dye dilution curves were processed on-line by a micro-computer. The mean transit time as well as myocardial blood flow were calculated from the step response function of the deconvoluted arterial and coronary venous signals. Reference flow was determined with an extracorporeal electromagnetic flowprobe within a coronary sinus bypass system. 38 steady states with coronary blood flow ranging from 49 - 333 ml/min*100g were analysed in 5 dogs. Mean transit times varied from 2.9 to 16.6 sec. An average intracoronary blood volume of 13.9 -7 1.8 m1/100g was calculated. The correlation between flow determined by the dye dilution technique and flow measured with the reference method was 0.98. According to these results determination of coronary blood flow with a double fiberoptic system and indocyanine green should be possible even under clinical conditions. Furthermore, the arterial and coronary venous oxygen saturation can be monitored continuously by the fiberoptic catheters. Therefore, additional information about the performance of the heart such as myocardial oxygen consumption and myocardial efficiency is available with the same equipment.
NASA Astrophysics Data System (ADS)
Uhrner, U.; von Löwis, S.; Vehkamäki, H.; Wehner, B.; Bräsel, S.; Hermann, M.; Stratmann, F.; Kulmala, M.; Wiedensohler, A.
Vehicle particle emissions are studied extensively because of their health effects, contribution to ambient PM levels and possible impact on climate. The aim of this work was to obtain a better understanding of secondary particle formation and growth in a diluting vehicle exhaust plume using 3-d information of simulations together with measurements. Detailed coupled computational fluid dynamics (CFD) and aerosol dynamics simulations have been conducted for H 2SO 4-H 2O and soot particles based on measurements within a vehicle exhaust plume under real conditions on public roads. Turbulent diffusion of soot and nucleation particles is responsible for the measured decrease of number concentrations within the diesel car exhaust plume and decreases coagulation rates. Particle size distribution measurements at 0.45 and 0.9 m distance to the tailpipe indicate a consistent soot mode (particle diameter Dp˜50 nm) at variable operating conditions. Soot mode number concentrations reached up to 10 13 m -3 depending on operating conditions and mixing. For nucleation particles the simulations showed a strong sensitivity to the spatial dilution pattern, related cooling and exhaust H 2SO 4(g). The highest simulated nucleation rates were about 0.05-0.1 m from the axis of the plume. The simulated particle number concentration pattern is in approximate accordance with measured concentrations, along the jet centreline and 0.45 and 0.9 m from the tailpipe. Although the test car was run with ultralow sulphur fuel, high nucleation particle ( Dp⩽15 nm) concentrations (>10 13 m -3) were measured under driving conditions of strong acceleration or the combination of high vehicle speed (>140 km h -1) and high engine rotational speed (>3800 revolutions per minute (rpm)). Strong mixing and cooling caused rapid nucleation immediately behind the tailpipe, so that the highest particle number concentrations were recorded at a distance, x=0.45 m behind the tailpipe. The simulated growth of H 2SO 4
Rebouche, C.J.; Pearson, G.A.; Serfass, R.E.; Roth, C.W.; Finley, J.W.
1986-03-01
Total body water (TBW) provides a useful measure of fat-free body mass. Deuterium (D) oxide isotope dilution is a useful method to determine TBW. Various techniques, including density, infrared absorption, mass spectrometry and gas chromatography have been employed to determine D enrichment in body fluids. Each of these methods requires extensive sample preparation (sublimation or distillation of the body fluid). The authors have employed nuclear magnetic resonance (NMR) spectroscopy to measure D enrichment in saliva and urine of human infants. No sample preparation was necessary. A standard (dg-t-butanol) was added to 0.5 ml of sample and D enrichment was measured using a JEOL FX-900 NMR spectrometer. Signal acquisition time was 4.7 min. Working range of D enrichment was 0.04-0.32 atom % D (corresponding to an oral dose of approximately 0.25-2.0 g D/sub 2/O/kg body weight). Coefficients of variation (c.v.) for saliva samples at 0.20 and 0.06 atom % enrichment were 1.97% and 4.78%, respectively. Mean (+/-SD) of TBW determinations for 6 infants was 58.5 +/- 5.4% of body weight (range 53-66%). Repeat measurements (3) of TBW for each infant at weekly intervals yielded a mean c.v. of 4.1% (n = 6). This method provides precise measurement of TBW without the extensive sample preparation requirements of previously-described methods.
In vivo measurement of myocardial protein turnover using an indicator dilution technique
Revkin, J.H.; Young, L.H.; Stirewalt, W.S.; Dahl, D.M.; Gelfand, R.A.; Zaret, B.L.; Barrett, E.J. )
1990-10-01
We applied a nondestructive tracer technique, previously developed for measuring skeletal muscle protein turnover, to the measurement of myocardial protein turnover in vivo. During a continuous infusion of L-(ring-2,6-3H)phenylalanine to anesthetized, overnight-fasted dogs, we measured the uptake of radiolabeled phenylalanine from plasma and the release of unlabeled phenylalanine from myocardial proteolysis using arterial and coronary sinus catheterization and analytic methods previously applied to skeletal muscle. Using these measurements, together with a model of myocardial protein synthesis that assumes rapid equilibration of tracer specific activity between myocardial phenylalanyl-tRNA and circulating phenylalanine, we estimated the rates of heart protein synthesis and degradation. The rate of heart protein synthesis was also estimated directly from the incorporation of labeled phenylalanine into tissue protein. The use of (3H)phenylalanine was compared with L-(1-14C)leucine in the measurement of heart protein turnover in dogs given simultaneous infusion of both tracers. Leucine uptake and release by the myocardium exceeded that of phenylalanine by 3.1 +/- 0.4- and 1.7 +/- 0.3-fold, respectively, consistent with leucine's 2.4-fold greater abundance in heart protein and its metabolism via other pathways. Phenylalanine is the preferred tracer for use with this method because of its limited metabolic fate in muscle. One theoretical limitation to the method, slow equilibration of circulating labeled phenylalanine with myocardial phenylalanyl-tRNA, was resolved by comparison of these specific activities after a 30-minute infusion of labeled phenylalanine in the rat. A second, empirical limitation involves precision in the measurement of the small decrements in phenylalanine specific activity that occur with each pass of blood through the coronary circulation.
NASA Astrophysics Data System (ADS)
Pura, Jose Luis; Muñoz, José María; Alejos, Óscar; Hernández-Gómez, Pablo; Torres, Carlos
2015-05-01
Transmission line techniques are a convenient way to determine the electromagnetic properties of a variety of materials in the ranges of radio and microwave frequencies. Traditional methods based on the measurement of the four scattering parameters can be successfully replaced for the method presented here, in which no change in the geometry is needed, since two independent measurements are carried out, with and without an applied magnetic field. In addition, given the small size of the sample holder, the required amount of material can be drastically reduced, and allow the use of a lumped circuit model, then reducing the inherent difficulties associated with the use of distributed parameters. Even though this kind of model requires the involved wavelengths to be much larger than the size of the system, this requirement can be overcome as long as the tested materials have relative ɛ or μ lower than 100. Furthermore, the use of short-circuited transmission lines simplifies sample holding and systematizes the measurement process, which is an important target when dealing with measurements within the radio and microwave frequency ranges.
NASA Astrophysics Data System (ADS)
Clements, Ethan; Ross, Preston; Rapp, Anthony; Cai, Hong; Reigle, Alex; Schlonsky, Eli; Lee, Hoseong; Clemens, James; Bali, Samir
2016-05-01
We experimentally investigate optical lattices using three different methods: pump-probe spectroscopy of vibrational energy levels, photon correlation of light scattered by cold atoms, and fluorescence imaging. Photon correlations of the scattered light can be used to measure lattice dwell times and crossover times between lattice sites. From this information we can derive the diffusion constant which can then be compared to direct measurement via fluorescence imaging. Furthermore, by Fourier transforming the time delayed photon correlations we can obtain the intensity spectrum which can be compared directly to pump-probe spectroscopy of the vibrational energy levels. We plan to carefully study situations in which the atomic transport properties deviate from Boltzman Gibbs statistics.
In vitro determination of accuracy of cardiac output measurements by thermal dilution.
Bilfinger, T V; Lin, C Y; Anagnostopoulos, C E
1982-11-01
The accuracy of cardiac output (C.O.) measurements by the thermodilution method was evaluated in an in vitro model within a flow range from 1 to 5 liters/min. For C.O. determinations, a 5F Swan-Ganz balloon-tipped thermodilution catheter and a 9520 Edwards computer were used. We made 420 measurements at known flow rates. In serial determinations, we achieved an overall accuracy of 86 to 93% compared to the reference flow; for single determinations, the accuracy ranged from 75 to 85%. The indicator volume (3, 5, or 10 cc) had no influence on the results. The thermodilution determinations at each flow rate were reproducible at between 2.5 and 8.5%. There was no difference in accuracy or reproducibility when ice-cold or room temperature saline was used. Caution in the interpretation of single C.O. determinations in low-flow states, i.e., in pediatric patients, is recommended.
Measurement of Acetylcholine in Rat Brain Microdialysates by LC – Isotope Dilution Tandem MS
Fryčák, P.; Stevens, S. M.; Nguyen, V.
2008-01-01
An LC-MS/MS method was developed for measuring acetylcholine (ACh) in an aqueous medium using reversed-phase ion-pair chromatography, electrospray ionization on a quadrupole ion trap instrument and a tetradeuterated analogue (ACh-1,1,2,2-d4) as an internal standard. A rapid separation was achieved on a 5-cm long octadecylsilica column (2.1 mm i.d.) by employing heptafluorobutyric acid (0.1% v/v) as an ion-pairing agent and requiring 10% v/v acetonitrile in 20 mM ammonium formate buffer under isocratic elution at 200 μl/min flow rate. The instrument’s response was calibrated with samples containing known mole ratios of ACh and ACh-1,1,2,2-d4 in an artificial cerebrospinal fluid, which afforded the conclusion that analyte concentrations could be determined by multiplying the measured analyte to internal standard ion-current ratio with the known molar concentration of the ACh-1,1,2,2-d4 added. The rapid and simple assay was tested by measuring the basal neurotransmitter concentration in rat brain microdialysates without the use of a cholinesterase inhibitor upon sample collection. PMID:19802332
Squashed entanglement in infinite dimensions
NASA Astrophysics Data System (ADS)
Shirokov, M. E.
2016-03-01
We analyse two possible definitions of the squashed entanglement in an infinite-dimensional bipartite system: direct translation of the finite-dimensional definition and its universal extension. It is shown that the both definitions produce the same lower semicontinuous entanglement measure possessing all basis properties of the squashed entanglement on the set of states having at least one finite marginal entropy. It is also shown that the second definition gives an adequate lower semicontinuous extension of this measure to all states of the infinite-dimensional bipartite system. A general condition relating continuity of the squashed entanglement to continuity of the quantum mutual information is proved and its corollaries are considered. Continuity bound for the squashed entanglement under the energy constraint on one subsystem is obtained by using the tight continuity bound for quantum conditional mutual information (proved in the Appendix by using Winter's technique). It is shown that the same continuity bound is valid for the entanglement of formation. As a result the asymptotic continuity of the both entanglement measures under the energy constraint on one subsystem is proved.
NASA Technical Reports Server (NTRS)
Witte, W. G.; Usry, J. W.; Whitlock, C. H.; Gurganus, E. A.
1977-01-01
The National Aeronautics and Space Administration (NASA), in cooperation with the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA), conducted a research program to evaluate the feasibility of remotely monitoring ocean dumping of waste products such as acid and sewage sludge. One aspect of the research program involved the measurements of upwelled spectral signatures for sewage-sludge mixtures of different concentrations in an 11600-liter tank. This paper describes the laboratory arrangement and presents radiance and reflectance spectra in the visible and near-infrared ranges for concentrations ranging from 9.7 to 180 ppm of secondary-treated sewage sludge mixed with two types of base water. Results indicate that upwelled radiance varies in a near-linear manner with concentration and that the sludge has a practically flat signal response between 420 and 970 nm. Reflectance spectra were obtained for the sewage-sludge mixtures at all wavelengths and concentrations.
Hirtz, Paul; Lovekin, Jim; Copp, John; Buck, Cliff; Adams, Mike
1993-01-28
A new technique has been developed for the measurement of steam mass flowrate, water mass flowrate and total enthalpy of two-phase fluids produced from geothermal wells. The method involves precisely metered injection of liquid and vapor phase tracers into the two-phase production pipeline and concurrent sampling of each phase downstream of the injection point. Subsequent chemical analysis of the steam and water samples for tracer content enables the calculation of mass flowrate for each phase given the known mass injection rates of tracer. This technique has now been used extensively at the Coso geothermal project, owned and operated by California Energy Company. Initial validation of the method was performed at the Roosevelt Hot Springs geothermal project on wells producing to individual production separators equipped with orificeplate flowmeters for each phase.
NASA Technical Reports Server (NTRS)
Usry, J. W.; Witte, W. G.; Whitlock, C. H.; Gurganus, E. A.
1979-01-01
Experimental measurements were made of upwelled spectral signatures of various concentrations of industrial waste products mixed with water in a large water tank. Radiance and reflectance spectra for a biosolid waste product (sludge) mixed with conditioned tap water and natural river water are reported. Results of these experiments indicate that reflectance increases with increasing concentration of the sludge at practically all wavelengths for concentration of total suspended solids up to 117 ppm in conditioned tap water and 171 ppm in natural river water. Significant variations in the spectra were observed and may be useful in defining spectral characteristics for this waste product. No significant spectral differences were apparent in the reflectance spectra of the two experiments, especially for wavelengths greater than 540 nm. Reflectance values, however, were generally greater in natural river water for wavelengths greater than 540 nm. Reflectance may be considered to increase linearly with concentration of total suspended solids from 5 to 171 ppm at all wavelengths without introducing errors larger than 10 percent.
Dilution Confusion: Conventions for Defining a Dilution
ERIC Educational Resources Information Center
Fishel, Laurence A.
2010-01-01
Two conventions for preparing dilutions are used in clinical laboratories. The first convention defines an "a:b" dilution as "a" volumes of solution A plus "b" volumes of solution B. The second convention defines an "a:b" dilution as "a" volumes of solution A diluted into a final volume of "b". Use of the incorrect dilution convention could affect…
Infinitely coloured black holes
NASA Astrophysics Data System (ADS)
Mavromatos, Nick E.; Winstanley, Elizabeth
2000-04-01
We formulate the field equations for SU (icons/Journals/Common/infty" ALT="infty" ALIGN="TOP"/> ) Einstein-Yang-Mills theory, and use an analytic approximation to elucidate the properties of spherically symmetric black hole solutions. This model may be motivated by string theory considerations, given the enormous gauge symmetries which characterize string theory. The solutions simplify considerably in the presence of a negative cosmological constant, particularly for the limiting cases of a very large cosmological constant or very small gauge field. The black holes possess infinite amounts of gauge field hair, and we speculate on possible consequences of this for quantum decoherence, which, however, we do not tackle here.
Horkley, J. J.; Carney, K. P.; Gantz, E. M.; Davies, J. E.; Lewis, R. R.; Crow, J. P.; Poole, C. A.; Grimes, T. S.; Giglio, J. J.
2015-03-17
Isotope dilution mass spectrometry (IDMS) is an analytical technique capable of providing accurate and precise quantitation of trace isotope abundance and assay providing measurement uncertainties below 1 %. To achieve these low uncertainties, the IDMS method ideally utilizes chemically pure “spike” solutions that consist of a single highly enriched isotope that is well-characterized relating to the abundance of companion isotopes and concentration in solution. To address a current demand for accurate 137Cs/137Ba ratio measurements for “age” determination of radioactive 137Cs sources, Idaho National Laboratory (INL) is producing enriched 134Ba isotopes that are tobe used for IDMS spikes to accurately determine 137Ba accumulation from the decay of 137Cs. The final objective of this work it to provide a homogenous set of reference materials that the National Institute of Standards and Technology can certify as standard reference materials used for IDMS. The process that was developed at INL for the separation and isolation of Ba isotopes, chemical purification of the isotopes in solution, and the encapsulation of the materials will be described.
J.J. Horkley; K.P E.M. Gantz; J.E. Davis; R.R. Lewis; J.P. Crow; C.A. Poole; T.S. Grimes; J.J. Giglio
2015-03-01
t Isotope dilution mass spectrometry (IDMS) is an analytical technique capable of providing accurate and precise quantitation of trace isotope abundance and assay providing measurement uncertainties below 1 %. To achieve these low uncertainties, the IDMS method ideally utilizes chemically pure ‘‘spike’’ solutions that consist of a single highly enriched isotope that is well-characterized relating to the abundance of companion isotopes and concentration in solution. To address a current demand for accurate 137Cs/137Ba ratio measurements for ‘‘age’’ determination of radioactive 137Cs sources, Idaho National Laboratory (INL) is producing enriched 134Ba isotopes that are tobe used for IDMS spikes to accurately determine 137Ba accumulation from the decay of 137Cs. The final objective of this work it to provide a homogenous set of reference materials that the National Institute of Standards and Technology can certify as standard reference materials used for IDMS. The process that was developed at INL for the separation and isolation of Ba isotopes, chemical purification of the isotopes in solution,
Horkley, J. J.; Carney, K. P.; Gantz, E. M.; Davies, J. E.; Lewis, R. R.; Crow, J. P.; Poole, C. A.; Grimes, T. S.; Giglio, J. J.
2015-03-17
Isotope dilution mass spectrometry (IDMS) is an analytical technique capable of providing accurate and precise quantitation of trace isotope abundance and assay providing measurement uncertainties below 1 %. To achieve these low uncertainties, the IDMS method ideally utilizes chemically pure “spike” solutions that consist of a single highly enriched isotope that is well-characterized relating to the abundance of companion isotopes and concentration in solution. To address a current demand for accurate 137Cs/137Ba ratio measurements for “age” determination of radioactive 137Cs sources, Idaho National Laboratory (INL) is producing enriched 134Ba isotopes that are tobe used for IDMS spikes to accurately determinemore » 137Ba accumulation from the decay of 137Cs. The final objective of this work it to provide a homogenous set of reference materials that the National Institute of Standards and Technology can certify as standard reference materials used for IDMS. The process that was developed at INL for the separation and isolation of Ba isotopes, chemical purification of the isotopes in solution, and the encapsulation of the materials will be described.« less
NASA Technical Reports Server (NTRS)
Eaton, John; Hwang, Wontae; Cabral, Patrick
2002-01-01
the addition of gravity as a variable parameter may help us to better understand the physics of turbulence attenuation. The experiments are conducted in a turbulence chamber capable of producing stationary or decaying isotropic turbulence with nearly zero mean flow and Taylor microscale Reynolds numbers up to nearly 500. The chamber is a 410 mm cubic box with the corners cut off to make it approximately spherical. Synthetic jet turbulence generators are mounted in each of the eight corners of the box. Each generator consists of a loudspeaker forcing a plenum and producing a pulsed jet through a 20 mm diameter orifice. These synthetic jets are directed into ejector tubes pointing towards the chamber center. The ejector tubes increase the jet mass flow and decrease the velocity. The jets then pass through a turbulence grid. Each of the eight loudspeakers is forced with a random phase and frequency. The resulting turbulence is highly Isotropic and matches typical behavior of grid turbulence. Measurements of both phases are acquired using particle image velocimetry (PIV). The gas is seeded with approximately 1 micron diameter seeding particles while the solid phase is typically 150 micron diameter spherical glass particles. A double-pulsed YAG laser and a Kodak ES-1.0 10-bit PIV camera provide the PIV images. Custom software is used to separate the images into individual images containing either gas-phase tracers or large particles. Modern high-resolution PIV algorithms are then used to calculate the velocity field. A large set of image pairs are acquired for each case, then the results are averaged both spatially and over the ensemble of acquired images. The entire apparatus is mounted in two racks which are carried aboard NASA's KC-135 Flying Microgravity Laboratory. The rack containing the turbulence chamber, the laser head, and the camera floats freely in the airplane cabin (constrained by competent NASA personnel) to minimize g-jitter.
Zhang, Tianjiao; Zhang, Chuanbao; Zhao, Haijian; Zeng, Jie; Zhang, Jiangtao; Zhou, Weiyan; Yan, Ying; Wang, Yufei; Wang, Mo; Chen, Wenxiang
2016-10-01
Accurate and precise glucose measurements are requisite for ensuring appropriate diagnosis and management of diseases related to hyperglycemia or hypoglycemia. It is necessary to have a higher order method to provide an accuracy base to which routine methods can be compared. We developed and evaluated a highly reliable measurement procedure based on isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) with a simple one-step derivatization. An appropriate amount of serum was accurately weighed and spiked with an isotope-labeled internal standard. After protein precipitation, the supernatant was reacted with 1-phenyl-3-methyl-5-pyrazolone for chemical structural transformation. The glucose derivatives were analyzed with LC-MS/MS in positive electrospray ionization mode. The within-run and total CVs ranged from 0.28 to 0.42 % and from 0.42 to 0.76 %, respectively, for a concentration range of 1.691 to 15.676 mmol/L. A regression comparison of the presented method to an existing RMP based on ID GC-MS showed agreement with no statistical difference (Y = 0.9985X-0.008; 95 % CI for the slope, 0.9966 to 1.001; 95 % CI for the intercept, -0.012 to 0.019). The structural analogs of glucose with a molecular mass of 180 were tested, and no significant interference effect was found. The limit of quantification was estimated to 0.8 ng glucose in absolute amount. This method is accurate, simple, and can serve as a candidate reference measurement procedure (RMP) in the establishment of a serum glucose reference system. PMID:27481169
NASA Astrophysics Data System (ADS)
Merlin, Frederic; Quirico, E.; Barucci, M. A.; Gourgeot, F.
2012-10-01
Observations performed in the mid infrared (MIR) show evidence of large amount of ices in the Galaxy. Water ice is the most abundant but other chemical compounds, such as carbon monoxide and methanol, can be present and be enriched in molecular clouds or protostellar disks (Garrod & Pauly 2011). Methanol forms mainly on ice-covered dust grain surfaces primarily through hydrogenation of CO or from an electron-irradiated H2O-CH4 icy mixture (see Moore & Hudson 1998 or Dartois et al. 1999). These compounds appear to be pristine in the minor bodies of the solar system (Merlin et al. 2012) and were found in comets (Bockelée-Morvan et al. 2004) and on the surface of Trans-Neptunian Objects and Centaurs (Barucci et al. 2012 for instance for methanol). Laboratory measurements are needed to constrain information on the physical and chemical properties of these objects and give constraint on the formation and evolution of the solar system. In the aim to give constraints on the physical properties of H2O and CH3OH from their spectral behavior, we performed laboratory measurements in the observable wavelength ranges accessible from the space and ground based observatories (in the MIR and in the near IR, respectively). We present new laboratory measurements depending on the ratio of each component and the ambient temperature (from 18 to 145K) for the amorphous and the crystalline phases. We focus our analyses on the effects of the dilution level of CH3OH in H2O and the phase changes, especially on the absorption bands located at 2,3 and 3,45 microns (associated to CH asymmetric stretch) and the possible formation of the mono hydrate CH3OH:H2O based on the 3,12 micron band (associated to the OH stretch).
NASA Astrophysics Data System (ADS)
Huang, K.; Bender, M. L.; Wanninkhof, R. H.; Cassar, N.
2013-12-01
Dissolved inorganic carbon (DIC) is one of the most important species in the ocean carbon system. An autonomous system using isotope dilution as its core method has been developed to obtain high-frequency measurements of dissolved inorganic carbon (DIC) concentrations in the surface ocean. This system accurately mixes a seawater sample and a 13C-labeled sodium bicarbonate solution (spike). The mixed solution is then acidified and sent through a gas permeable membrane contactor. CO2 derived from DIC in the mixture is extracted by a CO2-free gas stream, and is sent to a cavity ring-down spectrometer to analyze its 13C/12C ratio. [DIC] of the seawater can then be derived from the measured 13C/12C, the known mixing ratio and the [DI13C] of the spike. The method has been tested under a wide [DIC] range (1800-2800 μmol/kg) in the laboratory. It has also been deployed on a cruise that surveyed ocean waters to the south of Florida. At a sampling resolution of 4 minutes (15 samples per hour), the relative standard deviation of DIC determined from the laboratory tests and the field deployment is ×0.07% and ×0.09%, respectively. The accuracy of the method is better than 0.1% except where [DIC] varies faster than 5 μmol/kg per minute. Based on the laboratory and field evaluations, we conclude that this method can provide accurate underway [DIC] measurements at high resolution in most oceanic regions. Schematic illustration of the work flow.
Pagliano, Enea; Mester, Zoltán; Meija, Juris
2013-03-01
Since its introduction a century ago, isotope dilution analysis has played a central role in developments of analytical chemistry. This method has witnessed many elaborations and developments over the years. To date, we have single, double, and even triple isotope dilution methods. In this manuscript, we summarize the conceptual aspects of isotope dilution methods and introduce the quadruple dilution and the concept of exact matching triple and quadruple dilutions. The comparison of isotope dilution methods is performed by determination of bromide ions in groundwater using novel ethyl-derivatization chemistry in conjunction with GC/MS. We show that the benefits of higher-order isotope dilution methods are countered with a greater need for careful experimental design of the isotopic blends. Just as for ID(2)MS, ID(3)MS and ID(4)MS perform best when the isotope ratio of one sample/spike blend is matched with that of a standard/spike blend (exact matching).
Pagliano, Enea; Mester, Zoltán; Meija, Juris
2013-03-01
Since its introduction a century ago, isotope dilution analysis has played a central role in developments of analytical chemistry. This method has witnessed many elaborations and developments over the years. To date, we have single, double, and even triple isotope dilution methods. In this manuscript, we summarize the conceptual aspects of isotope dilution methods and introduce the quadruple dilution and the concept of exact matching triple and quadruple dilutions. The comparison of isotope dilution methods is performed by determination of bromide ions in groundwater using novel ethyl-derivatization chemistry in conjunction with GC/MS. We show that the benefits of higher-order isotope dilution methods are countered with a greater need for careful experimental design of the isotopic blends. Just as for ID(2)MS, ID(3)MS and ID(4)MS perform best when the isotope ratio of one sample/spike blend is matched with that of a standard/spike blend (exact matching). PMID:23371530
Hogan, D L; Turken, D; Stern, A I; Isenberg, J I
1983-11-01
Two in vivo methods that permit quantitation of gastric acid secretion immediately after the meal are currently in use: intragastric titration and the serial dilution indicator method. During intragastric titration, intragastric pH is artificially maintained at 5.5 to 7 by the continuous addition of alkali to the gastric contents, while during serial dilution the intragastric pH is permitted to seek its natural pH. This study compared gastric acid secretion and serum gastrin in response to a liquid protein meal measured by both techniques in 10 subjects. Mean (+/- SE) 3-hr acid outputs were almost identical (53.6 +/- 6.0 mmol/3 hr with intragastric titration and 52.0 +/- 8.5 mmol/3 hr with serial dilution indicator). Furthermore, 30 min secretory responses in individual subjects were highly correlated (r = 0.98 +/- 0.01, P less than 0.001). Also, in spite of intragastric pH being less than 1.5 by 90 min after the meal during the serial dilution method, total integrated serum gastrin concentrations after the meal were similar (intragastric titration = 20.6 +/- 7.3 ng min/ml versus serial dilution indicator = 23.5 +/- 9.8 ng min/ml) and individual 30-min gastrins during the two separate tests were highly correlated (r = 0.80 +/- 0.06, P less than 0.01). It is concluded that both meal-stimulated gastric acid secretion and serum gastrin concentrations as measured by intragastric titration and by the serial dilution indicator method produced similar results.
Stepanauskas, R.; Davidsson, E. T.; Leonardson, L.
1996-01-01
The effect of water infiltration rate (IR) on nitrogen cycling in a saturated wetland soil was investigated by applying a (sup15)N isotope dilution and pairing method. Water containing [(sup15)N]nitrate was infiltrated through 10-cm-long cores of sieved and homogenized soil at rates of 72, 168, 267, and 638 mm day(sup-1). Then the frequencies of (sup30)N(inf2), (sup29)N(inf2), (sup15)NO(inf3)(sup-), and (sup15)NH(inf4)(sup+) in the outflow water were measured. This method allowed simultaneous determination of nitrification, coupled and uncoupled denitrification, and nitrate assimilation rates. From 3% (at the highest IR) to 95% (at the lowest IR) of nitrate was removed from the water, mainly by denitrification. The nitrate removal was compensated for by the net release of ammonium and dissolved organic nitrogen. Lower oxygen concentrations in the soil at lower IRs led to a sharper decrease in the nitrification rate than in the ammonification rate, and, consequently, more ammonium leaked from the soil. The decreasing organic-carbon-to-nitrogen ratio (from 12.8 to 5.1) and the increasing light A(inf250)/A(inf365) ratio (from 4.5 to 5.2) indicated an increasing bioavailability of the outflowing dissolved organic matter with increasing IR. The efflux of nitrous oxide was also very sensitive to IR and increased severalfold when a zone of low oxygen concentration was close to the outlet of the soil cores. N(inf2)O then constituted 8% of the total gaseous N lost from the soil. PMID:16535352
Coertjens, Patrícia Chaves; Knorst, Marli Maria; Dumke, Anelise; Pasqualoto, Adriane Schmidt; Riboldi, João; Barreto, Sérgio Saldanha Menna
2013-01-01
OBJECTIVE: To compare TLC and RV values obtained by the single-breath helium dilution (SBHD) method with those obtained by whole-body plethysmography (WBP) in patients with normal lung function, patients with obstructive lung disease (OLD), and patients with restrictive lung disease (RLD), varying in severity, and to devise equations to estimate the SBHD results. METHODS: This was a retrospective cross-sectional study involving 169 individuals, of whom 93 and 49 presented with OLD and RLD, respectively, the remaining 27 having normal lung function. All patients underwent spirometry and lung volume measurement by both methods. RESULTS: TLC and RV were higher by WBP than by SBHD. The discrepancy between the methods was more pronounced in the OLD group, correlating with the severity of airflow obstruction. In the OLD group, the correlation coefficient of the comparison between the two methods was 0.57 and 0.56 for TLC and RV, respectively (p < 0.001 for both). We used regression equations, adjusted for the groups studied, in order to predict the WBP values of TLC and RV, using the corresponding SBHD values. It was possible to create regression equations to predict differences in TLC and RV between the two methods only for the OLD group. The TLC and RV equations were, respectively, ∆TLCWBP-SBHD in L = 5.264 − 0.060 × FEV1/FVC (r2 = 0.33; adjusted r2 = 0.32) and ∆RVWBP-SBHD in L = 4.862 − 0.055 × FEV1/FVC (r2 = 0.31; adjusted r2 = 0.30). CONCLUSIONS: The correction of TLC and RV results obtained by SBHD can improve the accuracy of this method for assessing lung volumes in patients with OLD. However, additional studies are needed in order to validate these equations. PMID:24473761
Students' Conception of Infinite Series
ERIC Educational Resources Information Center
Martinez-Planell, Rafael; Gonzalez, Ana Carmen; DiCristina, Gladys; Acevedo, Vanessa
2012-01-01
This is a report of a study of students' understanding of infinite series. It has a three-fold purpose: to show that students may construct two essentially different notions of infinite series, to show that one of the constructions is particularly difficult for students, and to examine the way in which these two different constructions may be…
Infinitely Large New Dimensions
Arkani-Hamed, Nima; Dimopoulos, Savas; Dvali, Gia; Kaloper, Nemanja
2000-01-24
We construct intersecting brane configurations in anitde Sitter (AdS) space which localize gravity to the intersection region, generalizing the trapping of gravity to any number n of infinite extra dimensions. Since the 4D Planck scale M{sub Pl} is determined by the fundamental Planck scale M{sub *} and the AdS radius L via the familiar relation M{sup 2}{sub Pl}{approx}M{sup 2+n}{sub *}L{sup n} , we get two kinds of theories with TeV scale quantum gravity and submillimeter deviations from Newton's law. With M{sub *}{approx}TeV and L{approx}submillimeter , we recover the phenomenology of theories with large extra dimensions. Alternatively, if M{sub *}{approx}L{sup -1}{approx}M{sub Pl} , and our 3-brane is at a distance of {approx}100M{sup -1}{sub Pl} from the intersection, we obtain a theory with an exponential determination of the weak/Planck hierarchy. (c) 2000 The American Physical Society.
Infinitely Large New Dimensions
Arkani-Hamed, Nima; Dimopoulos, Savas; Dvali, Gia; Kaloper, Nemanja
1999-07-29
We construct intersecting brane configurations in Anti-de-Sitter space localizing gravity to the intersection region, with any number n of extra dimensions. This allows us to construct two kinds of theories with infinitely large new dimensions, TeV scale quantum gravity and sub-millimeter deviations from Newton's Law. The effective 4D Planck scale M{sub Pl} is determined in terms of the fundamental Planck scale M{sub *} and the AdS radius of curvature L via the familiar relation M{sub Pl}{sup 2} {approx} M{sub *}{sup 2+n} L{sup n}; L acts as an effective radius of compactification for gravity on the intersection. Taking M{sub *} {approx} TeV and L {approx} sub-mm reproduces the phenomenology of theories with large extra dimensions. Alternately, taking M{sub *} {approx} L{sup -1} {approx} M{sub Pl}, and placing our 3-brane a distance {approx} 100M{sub Pl}{sup -1} away from the intersection gives us a theory with an exponential determination of the Weak/Planck hierarchy.
It has been fifty years since Kirkham and Bartholmew (1954) presented the conceptual framework and derived the mathematical equations that formed the basis of the now commonly employed method of 15N isotope dilution. Although many advances in methodology and analysis have been ma...
Gous, R M; Morris, T R
1985-04-01
Three experiments were conducted on male broiler chickens between one and three weeks of age to determine their response to dietary lysine concentrations. Serial dilutions of a summit diet shown to be first-limiting in lysine were fed in all experiments. The balance between amino acids in these diets was maintained within narrow limits. Intake of the most-limiting amino acid was the most important factor determining growth rate; protein intake as such was of little or no importance. The efficiency of utilisation of dietary lysine for protein growth was calculated to be 65.05 mg/g protein gain, representing a net efficiency of 0.85. The diet dilution technique overcomes the major disadvantage of the graded supplementation method for determining the requirements of amino acids, namely that of the amino acid balance changing systematically in successive dietary treatments.
Ferromagnetic of nanowires of infinite length and infinite thin films
NASA Astrophysics Data System (ADS)
Chacouche, Khaled; Hadiji, Rejeb
2015-12-01
The aim of the work described in this paper is to determine, via an asymptotic analysis, the limiting form of the free energy governing in the first case 3D ferromagnetic nanowires of infinite length in the limit and in the second case 3D thin films which become infinite when their thickness is vanished. A 1D limit problem on the nanowires and a 2D limit problem on the thin films are obtained.
Adjective with Infinitive in English and Polish
ERIC Educational Resources Information Center
Arabski, Janusz
1975-01-01
Deals with infinitives that occur with predicate adjectives. Syntactic relations occuring between Infinitive and Copula plus Adjective are examined with the aim of showing the Polish counterparts of English infinitives. (Author/RM)
Infinite swapping in curved spaces
NASA Astrophysics Data System (ADS)
Curotto, E.; Mella, Massimo
2014-01-01
We develop an extension of the infinite swapping and partial infinite swapping techniques [N. Plattner, J. D. Doll, P. Dupuis, H. Wang, Y. Liu, and J. E. Gubernatis, J. Chem. Phys. 135, 134111 (2011)] to curved spaces. Furthermore, we test the performance of infinite swapping and partial infinite swapping in a series of flat spaces characterized by the same potential energy surface model. We develop a second order variational algorithm for general curved spaces without the extended Lagrangian formalism to include holonomic constraints. We test the new methods by carrying out NVT classical ensemble simulations on a set of multidimensional toroids mapped by stereographic projections and characterized by a potential energy surface built from a linear combination of decoupled double wells shaped purposely to create rare events over a range of temperatures.
Science Notes: Dilution of a Weak Acid
ERIC Educational Resources Information Center
Talbot, Christopher; Wai, Chooi Khee
2014-01-01
This "Science note" arose out of practical work involving the dilution of ethanoic acid, the measurement of the pH of the diluted solutions and calculation of the acid dissociation constant, K[subscript a], for each diluted solution. The students expected the calculated values of K[subscript a] to be constant but they found that the…
Thermodynamics of Dilute Solutions.
ERIC Educational Resources Information Center
Jancso, Gabor; Fenby, David V.
1983-01-01
Discusses principles and definitions related to the thermodynamics of dilute solutions. Topics considered include dilute solution, Gibbs-Duhem equation, reference systems (pure gases and gaseous mixtures, liquid mixtures, dilute solutions), real dilute solutions (focusing on solute and solvent), terminology, standard states, and reference systems.…
Battezzati, A; Fiorillo, G; Spadafranca, A; Bertoli, S; Testolin, G
2006-07-15
A simple, highly selective, and sensitive method using stable isotope dilution and gas chromatography-mass spectrometry has been developed to quantify salicylic acid (SA) at concentrations naturally occurring in biological fluids, such as in the serum of subjects not taking aspirin. After extraction of liquid-liquid with diethyl ether and ethyl acetate and preparation of the tert-butyldimethylsilyl derivative, SA content was detected using deuterated SA as internal standard. The mean recovery of SA from serum was 85 +/- 6%. Intra- and interday precision and % relative error were <15% in all cases. With a detection limit of 0.6 ng and a quantification limit of 2 ng, the method is therefore also adequate for population studies because of the small amount of blood necessary to perform the analyses.
Raman measurements of dilute nitride alloys GaP(As)N grown on GaP substrates
NASA Astrophysics Data System (ADS)
Lazarenko, A.; Pirogov, E.; Sobolev, M.; Bukatin, A.; Nikitina, E.
2016-08-01
The structural properties of GaP(As)N dilute nitrides alloys grown on GaP substrates by molecular-beam epitaxy are investigated. The samples were studied by Raman scattering and high-resolution X-ray diffraction. In this work the impact of lattice mismatch of GaP(As)N layer and GaP substrate on the form of the spectrum of Raman scattering of samples was detected. It was shown that the addition of arsenic in solid solution GaPAsN can compensate the elastic stresses in the crystal lattice, and we can estimate the lattice mismatch between epitaxial layer GaP(As)N and GaP substrate by the intensity ratio of LOX/TOr phonon peaks.
Decoherence in infinite quantum systems
Blanchard, Philippe; Hellmich, Mario
2012-09-01
We review and discuss a notion of decoherence formulated in the algebraic framework of quantum physics. Besides presenting some sufficient conditions for the appearance of decoherence in the case of Markovian time evolutions we provide an overview over possible decoherence scenarios. The framework for decoherence we establish is sufficiently general to accommodate quantum systems with infinitely many degrees of freedom.
NASA Astrophysics Data System (ADS)
Wang, Chao; Zhang, Jingyu; Gao, Wenbin; Ding, Hongbing; Wu, Weiping
2015-11-01
The gas-solid two-phase flow has been widely applied in the power, chemical and metallurgical industries. It is of great significance in the research of gas-solid two-phase flow to measure particle velocity at different locations in the pipeline. Thus, an electrostatic sensor array comprising eight arc-shaped electrodes was designed. The relationship between the cross-correlation (CC) velocity and the distribution of particle velocity, charge density and electrode spatial sensitivity was analysed. Then the CC sensitivity and its calculation method were proposed. According to the distribution of CC sensitivity, it was found that, between different electrode pairs, it had different focus areas. The CC focus method was proposed for particle velocity measurement at different locations and validated by a belt-style electrostatic induction experiment facility. Finally, the particle velocities at different locations with different flow conditions were measured to research the particle velocity distribution in a dilute horizontal pneumatic conveying pipeline.
A unified approach to infinite-dimensional integration
NASA Astrophysics Data System (ADS)
Albeverio, S.; Mazzucchi, S.
2016-04-01
An approach to infinite-dimensional integration which unifies the case of oscillatory integrals and the case of probabilistic type integrals is presented. It provides a truly infinite-dimensional construction of integrals as linear functionals, as much as possible independent of the underlying topological and measure theoretical structure. Various applications are given, including, next to Feynman path integrals, Schrödinger and diffusion equations, as well as higher order hyperbolic and parabolic equations.
Krata, Agnieszka; Vassileva, Emilia; Bulska, Ewa
2016-11-01
The analytical procedures for reference measurements of the total Hg and methyl mercury (MeHg) mass fractions at various concentration levels in marine biota samples, candidates for certified reference materials (oyster and clam Gafrarium tumidum), were evaluated. Two modes of application of isotope dilution inductively coupled plasma mass spectrometry method (ID ICP-MS), namely direct isotope dilution and species-specific isotope dilution analysis with the use of two different quantification mass spectrometry techniques were compared. The entire ID ICP-MS measurement procedure was described by mathematical modelling and the combined uncertainty of measurement results was estimated. All factors influencing the final results as well as isotopic equilibrium were systematically investigated. This included the procedural blank, the moisture content in the biota samples and all factors affecting the blend ratio measurements (instrumental background, spectral interferences, dead time and mass discrimination effects as well as the repeatability of measured isotopic ratios). Modelling of the entire measurement procedures and the use of appropriate certified reference materials enable to assure the traceability of obtained values to the International System of Units (SI): the mole or the kilogram. The total mass fraction of mercury in oyster and clam biota samples, after correction for moisture contents, was found to be: 21.1 (1.1) 10(-9) kg kg(-1) (U =5.1% relative, k=2) and 390.0 (9.4) 10(-9) kg kg(-1) (U=2.4% relative, k=2), respectively. For the determination of mercury being present as methyl mercury, the non-chromatographic separation on anion-exchange resin AG1-X8 of the blended samples was applied. The content of MeHg (as Hg) in oyster sample was found: 4.81 (24) 10(-9)kgkg(-1) (U=5.0%, k=2) and 4.84 (21) 10(-9)kgkg(-1) (U=4.3%, k=2) with the use of quadrupole (ICP QMS) or sector field (ICP SFMS) inductively coupled plasma mass spectrometers, respectively. In the
Krata, Agnieszka; Vassileva, Emilia; Bulska, Ewa
2016-11-01
The analytical procedures for reference measurements of the total Hg and methyl mercury (MeHg) mass fractions at various concentration levels in marine biota samples, candidates for certified reference materials (oyster and clam Gafrarium tumidum), were evaluated. Two modes of application of isotope dilution inductively coupled plasma mass spectrometry method (ID ICP-MS), namely direct isotope dilution and species-specific isotope dilution analysis with the use of two different quantification mass spectrometry techniques were compared. The entire ID ICP-MS measurement procedure was described by mathematical modelling and the combined uncertainty of measurement results was estimated. All factors influencing the final results as well as isotopic equilibrium were systematically investigated. This included the procedural blank, the moisture content in the biota samples and all factors affecting the blend ratio measurements (instrumental background, spectral interferences, dead time and mass discrimination effects as well as the repeatability of measured isotopic ratios). Modelling of the entire measurement procedures and the use of appropriate certified reference materials enable to assure the traceability of obtained values to the International System of Units (SI): the mole or the kilogram. The total mass fraction of mercury in oyster and clam biota samples, after correction for moisture contents, was found to be: 21.1 (1.1) 10(-9) kg kg(-1) (U =5.1% relative, k=2) and 390.0 (9.4) 10(-9) kg kg(-1) (U=2.4% relative, k=2), respectively. For the determination of mercury being present as methyl mercury, the non-chromatographic separation on anion-exchange resin AG1-X8 of the blended samples was applied. The content of MeHg (as Hg) in oyster sample was found: 4.81 (24) 10(-9)kgkg(-1) (U=5.0%, k=2) and 4.84 (21) 10(-9)kgkg(-1) (U=4.3%, k=2) with the use of quadrupole (ICP QMS) or sector field (ICP SFMS) inductively coupled plasma mass spectrometers, respectively. In the
Using Weak-Lensing Dilution to Improve Measurements of the Luminous and Dark Matter in A1689
NASA Astrophysics Data System (ADS)
Medezinski, Elinor; Broadhurst, Tom; Umetsu, Keiichi; Coe, Dan; Benítez, Narciso; Ford, Holland; Rephaeli, Yoel; Arimoto, Nobuo; Kong, Xu
2007-07-01
The E/S0 sequence of a cluster defines a boundary redward of which a reliable weak-lensing signal can be obtained from background galaxies, uncontaminated by cluster members. For bluer colors, both background and cluster members are present, reducing the average distortion signal by the proportion of unlensed cluster members. In deep Subaru and HST/ACS images of A1689, the tangential distortion of galaxies with bluer colors falls rapidly toward the cluster center relative to lensing signal of the red background. We use this dilution effect to derive the cluster light profile and luminosity function to large radius, with the advantage that no subtraction of far-field background counts is required. The light profile declines smoothly to the limit of the data, r<2 h-1 Mpc, with a constant slope, dlog(L)/dlog(r)=-1.12+/-0.06, unlike the lensing mass profile which steepens continuously with radius, so that M/L peaks at an intermediate radius, ~=100 h-1 kpc. A flatter behavior is found for the more physically meaningful ratio of dark matter to stellar matter when accounting for the color-mass relation of cluster members. The cluster luminosity function has a flat slope, α=-1.05+/-0.05, independent of radius and with no faint upturn to Mi'<-12. We establish that the very bluest objects are negligibly contaminated by the cluster [(V-i')AB<0.2], because their distortion profile rises toward the center following the red background, but offset higher by ~=20%. This larger amplitude is consistent with the greater estimated depth of the faint blue galaxies,
Activities of chromium in molten copper at dilute concentrations by solid-state electrochemical cell
NASA Astrophysics Data System (ADS)
Inouye, T. K.; Fujiwara, H.; Iwase, M.
1991-08-01
In order to obtain the activities of chromium in molten copper at dilute concentrations (<0.008 chromium mole fractions), liquid copper was brought to equilibrium with molten CaCl2 + Cr2O3 slag saturated with Cr2O3 (s), at temperatures between 1423 and 1573 K, and the equilibrium oxygen partial pressures were measured by means of solid-oxide galvanic cells of the type Mo/Mo + MoO2/ZrO2(MgO)/(Cu + Cr))alloy + Cr2O3 + (CaCl2 + Cr2O3)slag/Mo. The free energy changes for the dissolution of solid chromium in molten copper at infinite dilution referred to 1 wt pct were determined as Cr (s) = Cr(1 wt pct, in Cu) and Δ G° = + 97,000 + 73.3 (T/K) ± 2,000 J mol-1.
Serial Dilution Simulation Lab
ERIC Educational Resources Information Center
Keler, Cynthia; Balutis, Tabitha; Bergen, Kim; Laudenslager, Bryanna; Rubino, Deanna
2010-01-01
Serial dilution is often a difficult concept for students to understand. In this short dry lab exercise, students perform serial dilutions using seed beads. This exercise helps students gain skill at performing dilutions without using reagents, bacterial cultures, or viral cultures, while being able to visualize the process.
Infinite resources: the ultimate strategy.
Goeller, H E; Zucker, A
1984-02-01
By projecting global population growth and demand for nonrenewable materials over the next century, it appears unlikely that the world will run short of any element before about 2050. This provides considerable time to develop new technology to economically exploit lower grade and alternative ores to bring some 30 elements into essentially infinite supply, and to use these elements in developing substitutes to satisfy the requirements of modern civilized societies. PMID:17781431
Calculators to Motivate Infinite Composition of Functions.
ERIC Educational Resources Information Center
McCune, E. D.; And Others
1980-01-01
This paper demonstrates how calculators may be used to motivate a concept called infinite composition of functions. Several mathematical topics, such as continued square roots, continued fractions, and infinite products are treated and discussed as special cases. (Author/MK)
Teleportation schemes in infinite dimensional Hilbert spaces
Fichtner, Karl-Heinz; Freudenberg, Wolfgang; Ohya, Masanori
2005-10-01
The success of quantum mechanics is due to the discovery that nature is described in infinite dimension Hilbert spaces, so that it is desirable to demonstrate the quantum teleportation process in a certain infinite dimensional Hilbert space. We describe the teleportation process in an infinite dimensional Hilbert space by giving simple examples.
Grolier, Jean-Pierre E.; del Río, Jose Manuel
2009-01-01
We have performed a detailed study of the thermodynamics of the titration process in an isothermal titration calorimeter with full cells. We show that the relationship between the enthalpy and the heat measured is better described in terms of the equation Δ H = Winj + Q (where Winj is the work necessary to carry out the titration) than in terms of ΔH = Q. Moreover, we show that the heat of interaction between two components is related to the partial enthalpy of interaction at infinite dilution of the titrant component, as well as to its partial volume of interaction at infinite dilution. PMID:20054472
Preston, Tom
2014-01-01
This paper discusses some of the recent improvements in instrumentation used for stable isotope tracer measurements in the context of measuring retinol stores, in vivo. Tracer costs, together with concerns that larger tracer doses may perturb the parameter under study, demand that ever more sensitive mass spectrometric techniques are developed. GCMS is the most widely used technique. It has high sensitivity in terms of sample amount and uses high resolution GC, yet its ability to detect low isotope ratios is limited by background noise. LCMSMS may become more accessible for tracer studies. Its ability to measure low level stable isotope tracers may prove superior to GCMS, but it is isotope ratio MS (IRMS) that has been designed specifically for low level stable isotope analysis through accurate analysis of tracer:tracee ratios (the tracee being the unlabelled species). Compound-specific isotope analysis, where GC is interfaced to IRMS, is gaining popularity. Here, individual 13C-labelled compounds are separated by GC, combusted to CO2 and transferred on-line for ratiometric analysis by IRMS at the ppm level. However, commercially-available 13C-labelled retinol tracers are 2 - 4 times more expensive than deuterated tracers. For 2H-labelled compounds, GC-pyrolysis-IRMS has now become more generally available as an operating mode on the same IRMS instrument. Here, individual compounds are separated by GC and pyrolysed to H2 at high temperature for analysis by IRMS. It is predicted that GC-pyrolysis-IRMS will facilitate low level tracer procedures to measure body retinol stores, as has been accomplished in the case of fatty acids and amino acids. Sample size requirements for GC-P-IRMS may exceed those of GCMS, but this paper discusses sample preparation procedures and predicts improvements, particularly in the efficiency of sample introduction.
Coulson, B S; Grimwood, K; Bishop, R F; Barnes, G L
1989-10-01
In order to facilitate measurement of antirotaviral IgA in large collections of faeces and secretions, adaptations of enzyme immunoassay methods for estimating antirotaviral IgA and IgM in duodenal fluid, saliva, faeces and serum were studied. To quantitate specific IgA, a single dilution of each sample was assayed. Results were expressed as antirotaviral IgA units derived from a standard curve. Units were calculated by log-logit analysis on computer. There was strong correlation between antirotaviral IgA units and end-point titres in 257 faecal samples (correlation coefficient r = 0.92) and in 182 duodenal fluids and salivary samples (correlation coefficient r = 0.74). The assay was validated using acute and convalescent faeces from children with or without rotavirus infection. Immune conversions in IgA were detected in 33 (75%) of the children by units and 34 (77%) by titres. None of nine children with gastroenteritis due to other infectious agents showed immune conversions to rotavirus. A monoclonal capture IgM assay showed similar end-point titres and numbers of immune conversions when compared with a direct assay for antirotaviral IgM in serum and secretions. Use of the capture method eliminated false-positive reactions with the cell control. The assay for antirotaviral IgA units in secretions is simple, rapid, reproducible and reliable, and has proven of value in longitudinal epidemiological studies of rotavirus coproIgA profiles. Both the capture IgM technique and the single dilution IgA method permit analysis of large numbers of specimens and are appropriate for examination of immune responses to natural rotavirus infection or during vaccine trials.
Microfluidic serial dilution ladder.
Ahrar, Siavash; Hwang, Michelle; Duncan, Philip N; Hui, Elliot E
2014-01-01
Serial dilution is a fundamental procedure that is common to a large number of laboratory protocols. Automation of serial dilution is thus a valuable component for lab-on-a-chip systems. While a handful of different microfluidic strategies for serial dilution have been reported, approaches based on continuous flow mixing inherently consume larger amounts of sample volume and chip real estate. We employ valve-driven circulatory mixing to address these issues and also introduce a novel device structure to store each stage of the dilution process. The dilution strategy is based on sequentially mixing the rungs of a ladder structure. We demonstrate a 7-stage series of 1 : 1 dilutions with R(2) equal to 0.995 in an active device area of 1 cm(2).
Chatterjee, Barun Kumar
2014-04-01
The major objection to homeopathic medicine is that the doses of medicine prescribed in some cases are too dilute for any active ingredient to be present. The medicines would hence be rendered inactive, necessitating novel explanations for the action. A further examination of dilution in the light of the Langmuir equation shows that homeopathic medicines may not be as dilute as a simplistic application of Avogadro's Principle suggests, due to surface effects.
Liu, Hong; Wong, Lingkai; Yong, Sharon; Liu, Qinde; Lee, Tong Kooi
2015-10-01
The development of reference measurement methods for hemoglobin A1c (HbA1c) is important for quality assurance in diabetes management. The IFCC reference method using purified proteins as calibration standards is the recommended accuracy-based reference method for the standardization of HbA1c measurement. We developed a highly precise and accurate liquid chromatography-isotope-dilution tandem mass spectrometry (LC-IDMS/MS) procedure, which can serve as an alternative accuracy-based method for HbA1c measurement. In this method, enzymatic proteolysis was applied to sample preparation, followed by LC-IDMS/MS measurement of hemoglobin A0 (HbA0) and HbA1c, using two "signature" hexapeptides for calibration. The concentrations of the signature hexapeptide calibration solutions were, in turn, determined using a hydrolysis method with HCl, followed by LC-IDMS/MS measurement using amino acid solutions as calibration standards. These solutions were gravimetrically prepared from pure amino acid certified reference materials (CRMs). The developed LC-IDMS/MS method was used in participation in an IFCC ring trial for reference laboratories (RELA 2013 and 2014) for HbA1c, where our results were compared with those using the IFCC reference method. The deviations were found to be 0.4-1.7 mmol mol(-1) [or 0.04-0.16% in National Glygohemoglobin Standardization Program (NGSP) units], revealing good comparability with the IFCC reference method. The relative expanded uncertainty of the LC-IDMS/MS was in the range of 2.6% to 2.8% (1.6% to 2.2% after converting to NGSP units). With excellent method precision, good comparability with the IFCC reference method, and a small measurement uncertainty, the developed LC-IDMS/MS method may be used as an alternative accuracy-based reference method for HbA1c measurement.
Jaruga, Pawel; Xiao, Yan; Nelson, Bryant C.; Dizdaroglu, Miral
2009-09-04
Oxidatively induced DNA lesions (5'R)- and (5'S)-8,5'-cyclo-2'-deoxyadenosines (R-cdA and S-cdA) are detectable and accumulate in vivo due to disease states and defects in DNA repair. They block transcription and inhibit gene expression, and may play a role in disease processes. Accurate measurement of these lesions in DNA in vivo is necessary to understand their biological effects. We report on a methodology using liquid chromatography/isotope-dilution tandem mass spectrometry to measure R-cdA and S-cdA in DNA. This methodology permitted the detection of these compounds at a level of 0.1 fmol on-column. Levels of R-cdA and S-cdA in mouse liver DNA amounted to 0.133 {+-} 0.024 and 0.498 {+-} 0.065 molecules/10{sup 7} DNA 2'-deoxynucleosides, respectively. The successful measurement of R-cdA and S-cdA in DNA in vivo suggests that this methodology will be used for understanding of their repair and biological consequences, and that these compounds may be used as putative biomarkers for disease states.
Doveil, F.; Lejeune, A.; Chérigier-Kovacic, L.
2013-05-15
The interaction between a metastable H(2s) atomic hydrogen beam and an external electric field leads to the emission of the Lyman-α line. It originates in the Stark mixing of the near-degenerate 2s{sub 1/2} and 2p{sub 1/2} levels separated by the Lamb shift. The quenched radiation proportional to the square of the electric field amplitude is recovered in vacuum by using such an atomic probe beam. For larger electric field, saturation is observed and related to the beam finite transit time. We also observe the strong enhancement of the signal when the field is oscillating at the Lamb shift frequency. This technique is applied in a plasma, offering an alternative way to measure weak electric fields by direct and non-intrusive means.
NASA Astrophysics Data System (ADS)
Doveil, Fabrice
2012-10-01
The interaction between a metastable H(2s) atomic hydrogen beam and an external electric field leads to the emission of the Lyman-α line. It originates in the Stark mixing of the near-degenerate 2s1/2 and 2p1/2 levels separated by the Lamb shift [1]. The quenched radiation proportional to the square of the electric field amplitude is recovered in vacuum by using such an atomic probe beam. For larger electric field, saturation is observed and related to the beam finite transit time. We also observe the strong enhancement of the signal when the field is oscillating at the Lamb shift frequency. This technique is applied in a plasma, offering an alternative way to measure weak electric fields by direct and non-intrusive means [2]. [4pt] This work was inspired by late Prof. R.A. Stern to whom it is dedicated. It was done in collaboration with L. Ch'erigier-Kovacic. It was the subject of A. Lejeune's PhD thesis and was supported by a grant from Ministère de la Recherche. The author acknowledges the help of G. Bachet and G. Prasad for the conception and construction of the experimental set-up. [4pt] [1] W.E. Lamb, Jr., Rep. Prog. Phys. 14, 19 (1951)[0pt] [2] A. Lejeune, L. Ch'erigier-Kovacic, F. Doveil, Appl. Phys. Lett. 99, 181502 (2011)
Phase transitions in pure and dilute thin ferromagnetic films
NASA Astrophysics Data System (ADS)
Korneta, W.; Pytel, Z.
1983-10-01
The mean-field model of a thin ferromagnetic film where the nearest-neighbor exchange coupling in surface layers can be different from that inside the film is considered. The phase diagram, equations for the second-order phase-transition lines, and the spontaneous magnetization profiles near the phase transitions are given. It is shown that there is no extra-ordinary transition in a thin film. If the thickness of the film tends to infinity the well-known results for the mean-field model of a semi-infinite ferromagnet are obtained. The generalization for disordered dilute thin ferromagnetic films and semi-infinite ferromagnets is also given.
Yang, Ruiyue; Dong, Jun; Guo, Hanbang; Li, Hongxia; Wang, Shu; Zhao, Haijian; Zhou, Weiyan; Yu, Songlin; Wang, Mo; Chen, Wenxiang
2013-01-01
Background Serum branched-chain and aromatic amino acids (BCAAs and AAAs) have emerged as predictors for the future development of diabetes and may aid in diabetes risk assessment. However, the current methods for the analysis of such amino acids in biological samples are time consuming. Methods An isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) method for serum BCAAs and AAAs was developed. The serum was mixed with isotope-labeled BCAA and AAA internal standards and the amino acids were extracted with acetonitrile, followed by analysis using LC/MS/MS. The LC separation was performed on a reversed-phase C18 column, and the MS/MS detection was performed via the positive electronic spray ionization in multiple reaction monitoring mode. Results Specific analysis of the amino acids was achieved within 2 min. Intra-run and total CVs for the amino acids were less than 2% and 4%, respectively, and the analytical recoveries ranged from 99.6 to 103.6%. Conclusion A rapid and precise method for the measurement of serum BCAAs and AAAs was developed and may serve as a quick tool for screening serum BCAAs and AAAs in studies assessing diabetes risk. PMID:24339906
Newby, M.J.; Keim, N.L.; Brown, D.L. )
1990-08-01
This study contrasts body compositions (by six methods) of eight cystic fibrosis (CF) subjects with those of eight control subjects matched for age, height, and sex. CF subjects weighed 84% as much as control subjects. Densitometry and two bioelectrical impedance-analysis methods suggested that reduced CF weights were due to less lean tissue (10.7, 9.5, and 10.4 kg). Total-body electrical conductivity (TOBEC) and skinfold-thickness measurements indicated that CF subjects were leaner than control subjects and had less fat (5.4 and 3.6 kg) and less lean (5.2 and 7 kg) tissue. D2O dilution showed a pattern similar to TOBEC (8.3 kg less lean, 2.7 kg less fat tissue). Densitometry estimates of fat (mass and percent) were not correlated (r less than 0.74, p greater than 0.05) with any other method for CF subjects but were correlated with all other methods for control subjects. CF subjects contained less fat and lean tissue than did control subjects. Densitometry by underwater weighing is unsuitable for assessing body composition of CF patients.
Cook, Gillian R.; Krithika, S; Edwards, Melissa; Kavanagh, Paula
2014-01-01
Genetic association studies require a quantitative and reliable method for odor threshold assessment in order to examine the contribution of genetic variants to complex olfactory phenotypes. Our main goal was to assess the feasibility of a portable Scentroid air dilution olfactometer for use in such studies. Using the Scentroid SM110C and the SK5 n-butanol Sensitivity Kit (IDES Canada Inc.), n-butanol odor thresholds were determined for 182 individuals of diverse ancestry (mean age: 20.4 ± 2.5 years; n = 128 female; n = 54 male). Threshold scores from repeat participants were used to calculate a test–retest reliability coefficient, which was statistically significant (r = 0.754, p < 0.001, n = 29), indicating that the Scentroid provides reliable estimates of odor thresholds. In addition, we performed a preliminary genetic analysis evaluating the potential association of n-butanol odor thresholds to six single-nucleotide polymorphisms (SNPs) putatively involved in general olfactory sensitivity (GOS). The results of multiple linear regression analysis revealed no significant association between the SNPs tested and threshold scores. However, our sample size was relatively small, and our study was only powered to identify genetic markers with strong effects on olfactory sensitivity. Overall, we find that the Scentroid provides reliable quantitative measures of odor detection threshold and is well suited for genetic studies of olfactory sensitivity. PMID:25392755
Adkins, Erin M; Miller, J Houston
2015-01-28
Visible light extinction was measured in a series of nitrogen-diluted, ethylene/air, non-premixed flames and this data was used to determine the optical band gap, OBG, as a function of flame position. Collimated light from a supercontinuum source is telescopically expanded and refocused to match the f- number of a dispersing monochromator. The dispersed light is split into a power metering channel and a channel that is periscoped and focused into the flame. The transmitted light is then recollimated and focussed onto a silicon photodiode detector. After tomographic reconstruction of the radial extinction field, the OBG was derived from the near-edge absorption feature using Tauc/Davis-Mott analysis. A slight evolution in OBG was observed throughout all flame systems with a consistent range of OBG observed between approximately 1.85 eV and 2.35 eV. Averaging over all positions the mean OBG was approximately 2.09 eV for all flame systems. Comparing these results to previously published computational results relating calculated HOMO-LUMO gaps for a variety of D2h PAH molecules to the number of aromatic rings in the structure, showed that the observed optical band gap is consistent with a PAH of about 14 rings or a conjugation length of 0.97 nm. This work provides experimental support to the model of soot formation where the transition from chemical to physical growth starts at a modest molecular size; about the size of circumpyrene.
Shen, Chuan-Chou; Cheng, Hai; Edwards, R Lawrence; Moran, S Bradley; Edmonds, Henrietta N; Hoff, John A; Thomas, Rebecca B
2003-03-01
A technique has been developed to quantify ultratrace 231Pa (50-2000 ag; 1 ag = 10(-18) g) concentrations in seawater using isotope-dilution thermal ionization mass spectrometry (TIMS). The method is a modification of a process developed by Pickett et al. (Pickett, D. A.; Murrell, M. T.; Williams, R. W. Anal. Chem. 1994, 66, 1044-1049) and extends the technique to very low levels of protactinium. The procedural blank is 16 +/- 15 ag (2sigma), and the ionization efficiency (ions generated/atom loaded) approaches 0.5%. Measurement time is <1 h. The amount of 231Pa needed to produce 231Pa data with an uncertainty of +/-4-12% is 100-1000 ag (approximately 3 x 10(5) to 3 x 10(6) atoms). Replicate measurements made on known standards and seawater samples demonstrate that the analytical precision approximates that expected from counting statistics and that, based on detection limits of 38 and 49 ag, protactinium can be detected in a minimum sample size of surface seawater of approximately 2 L for suspended particulate matter and <0.1 L for filtered (<0.4 microm) seawater, respectively. The concentration of 231Pa (tens of attograms per liter) can be determined with an uncertainty of +/-5-10% (2sigma) for suspended particulate matter filtered from 5 to 10 L of seawater. For the dissolved fraction, 0.5-1 L of seawater yields 231Pa measurements with a precision of 1-10%. Sample size requirements are orders of magnitude less than traditional decay-counting techniques and significantly less than previously reported ICP-MS techniques. Our technique can also be applied to other environmental samples, including cave waters, rivers, and igneous rocks.
Shen, Chuan-Chou; Cheng, Hai; Edwards, R Lawrence; Moran, S Bradley; Edmonds, Henrietta N; Hoff, John A; Thomas, Rebecca B
2003-03-01
A technique has been developed to quantify ultratrace 231Pa (50-2000 ag; 1 ag = 10(-18) g) concentrations in seawater using isotope-dilution thermal ionization mass spectrometry (TIMS). The method is a modification of a process developed by Pickett et al. (Pickett, D. A.; Murrell, M. T.; Williams, R. W. Anal. Chem. 1994, 66, 1044-1049) and extends the technique to very low levels of protactinium. The procedural blank is 16 +/- 15 ag (2sigma), and the ionization efficiency (ions generated/atom loaded) approaches 0.5%. Measurement time is <1 h. The amount of 231Pa needed to produce 231Pa data with an uncertainty of +/-4-12% is 100-1000 ag (approximately 3 x 10(5) to 3 x 10(6) atoms). Replicate measurements made on known standards and seawater samples demonstrate that the analytical precision approximates that expected from counting statistics and that, based on detection limits of 38 and 49 ag, protactinium can be detected in a minimum sample size of surface seawater of approximately 2 L for suspended particulate matter and <0.1 L for filtered (<0.4 microm) seawater, respectively. The concentration of 231Pa (tens of attograms per liter) can be determined with an uncertainty of +/-5-10% (2sigma) for suspended particulate matter filtered from 5 to 10 L of seawater. For the dissolved fraction, 0.5-1 L of seawater yields 231Pa measurements with a precision of 1-10%. Sample size requirements are orders of magnitude less than traditional decay-counting techniques and significantly less than previously reported ICP-MS techniques. Our technique can also be applied to other environmental samples, including cave waters, rivers, and igneous rocks. PMID:12641225
Dilution and the elusive baseline.
Likens, Gene E; Buso, Donald C
2012-04-17
Knowledge of baseline conditions is critical for evaluating quantitatively the effect of human activities on environmental conditions, such as the impact of acid deposition. Efforts to restore ecosystems to prior, "pristine" condition require restoration targets, often based on some presumed or unknown baseline condition. Here, we show that rapid and relentless dilution of surface water chemistry is occurring in the White Mountains of New Hampshire, following decades of acid deposition. Extrapolating measured linear trends using a unique data set of up to 47 years, suggest that both precipitation and streamwater chemistry (r(2) >0.84 since 1985) in the Hubbard Brook Experimental Forest (HBEF) will approximate demineralized water within one to three decades. Because such dilute chemistry is unrealistic for surface waters, theoretical baseline compositions have been calculated for precipitation and streamwater: electrical conductivity of 3 and 5 μS/cm, base cation concentrations of 7 and 39 μeq/liter, acid-neutralizing capacity values of <1 and 14 μeq/liter, respectively; and pH 5.5 for both. Significantly large and rapid dilution of surface waters to values even more dilute than proposed for Pre-Industrial Revolution (PIR) conditions has important ecological, biogeochemical and water resource management implications, such as for the success of early reproductive stages of aquatic organisms.
Dilution and the elusive baseline.
Likens, Gene E; Buso, Donald C
2012-04-17
Knowledge of baseline conditions is critical for evaluating quantitatively the effect of human activities on environmental conditions, such as the impact of acid deposition. Efforts to restore ecosystems to prior, "pristine" condition require restoration targets, often based on some presumed or unknown baseline condition. Here, we show that rapid and relentless dilution of surface water chemistry is occurring in the White Mountains of New Hampshire, following decades of acid deposition. Extrapolating measured linear trends using a unique data set of up to 47 years, suggest that both precipitation and streamwater chemistry (r(2) >0.84 since 1985) in the Hubbard Brook Experimental Forest (HBEF) will approximate demineralized water within one to three decades. Because such dilute chemistry is unrealistic for surface waters, theoretical baseline compositions have been calculated for precipitation and streamwater: electrical conductivity of 3 and 5 μS/cm, base cation concentrations of 7 and 39 μeq/liter, acid-neutralizing capacity values of <1 and 14 μeq/liter, respectively; and pH 5.5 for both. Significantly large and rapid dilution of surface waters to values even more dilute than proposed for Pre-Industrial Revolution (PIR) conditions has important ecological, biogeochemical and water resource management implications, such as for the success of early reproductive stages of aquatic organisms. PMID:22455659
Sun, Guohui; Zhao, Lijiao; Fan, Tengjiao; Ren, Ting; Zhong, Rugang
2016-10-15
The repair of DNA mediated by O(6)-alkylguanine-DNA alkyltransferase (AGT) provides protection against DNA damage from endogenous or exogenous alkylation of the O(6) position of guanine. However, this repair acts as a double-edged sword in cancer treatment, as it not only protects normal cells from chemotherapy-associated toxicities, but also results in cancer cell resistance to guanine O(6)-alkylating antitumour agents. Thus, AGT plays an important role in predicting the individual susceptibility to guanine O(6)-alkylating carcinogens and chemotherapies. Accordingly, it is necessary to establish a quantitative method for determining AGT activity with high accuracy, sensitivity and practicality. Here, we describe a novel nonradioactive method for measuring AGT activity using stable isotope dilution high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). This method is based on the irreversibility of the removal of the O(6)-alkyl group from guanine by AGT and on the high affinity of O(6)-benzylguanine (O(6)-BG) as an AGT substrate. HPLC-ESI-MS/MS was used to measure the AGT activities in cell protein extracts from eight tumour lines, demonstrating that AGT activity was quite variable among different cell lines, ranging from nondetectable to 1021 fmol/mg protein. The experiments performed in intact tumour cells yielded similar results but exhibited slightly higher activities than those observed in cell protein extracts. The accuracy of this method was confirmed by an examination of AGT expression levels using western blotting analysis. To our knowledge, this method is the first mass spectrometry-based AGT activity assay, and will likely provide assistance in the screening of cancer risk or the application of chemotherapies. PMID:27544051
Sun, Guohui; Zhao, Lijiao; Fan, Tengjiao; Ren, Ting; Zhong, Rugang
2016-10-15
The repair of DNA mediated by O(6)-alkylguanine-DNA alkyltransferase (AGT) provides protection against DNA damage from endogenous or exogenous alkylation of the O(6) position of guanine. However, this repair acts as a double-edged sword in cancer treatment, as it not only protects normal cells from chemotherapy-associated toxicities, but also results in cancer cell resistance to guanine O(6)-alkylating antitumour agents. Thus, AGT plays an important role in predicting the individual susceptibility to guanine O(6)-alkylating carcinogens and chemotherapies. Accordingly, it is necessary to establish a quantitative method for determining AGT activity with high accuracy, sensitivity and practicality. Here, we describe a novel nonradioactive method for measuring AGT activity using stable isotope dilution high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). This method is based on the irreversibility of the removal of the O(6)-alkyl group from guanine by AGT and on the high affinity of O(6)-benzylguanine (O(6)-BG) as an AGT substrate. HPLC-ESI-MS/MS was used to measure the AGT activities in cell protein extracts from eight tumour lines, demonstrating that AGT activity was quite variable among different cell lines, ranging from nondetectable to 1021 fmol/mg protein. The experiments performed in intact tumour cells yielded similar results but exhibited slightly higher activities than those observed in cell protein extracts. The accuracy of this method was confirmed by an examination of AGT expression levels using western blotting analysis. To our knowledge, this method is the first mass spectrometry-based AGT activity assay, and will likely provide assistance in the screening of cancer risk or the application of chemotherapies.
Understanding the Behaviour of Infinite Ladder Circuits
ERIC Educational Resources Information Center
Ucak, C.; Yegin, K.
2008-01-01
Infinite ladder circuits are often encountered in undergraduate electrical engineering and physics curricula when dealing with series and parallel combination of impedances, as a part of filter design or wave propagation on transmission lines. The input impedance of such infinite ladder circuits is derived by assuming that the input impedance does…
Improving the Instruction of Infinite Series
ERIC Educational Resources Information Center
Lindaman, Brian; Gay, A. Susan
2012-01-01
Calculus instructors struggle to teach infinite series, and students have difficulty understanding series and related concepts. Four instructional strategies, prominently used during the calculus reform movement, were implemented during a 3-week unit on infinite series in one class of second-semester calculus students. A description of each…
Scalable L-infinite coding of meshes.
Munteanu, Adrian; Cernea, Dan C; Alecu, Alin; Cornelis, Jan; Schelkens, Peter
2010-01-01
The paper investigates the novel concept of local-error control in mesh geometry encoding. In contrast to traditional mesh-coding systems that use the mean-square error as target distortion metric, this paper proposes a new L-infinite mesh-coding approach, for which the target distortion metric is the L-infinite distortion. In this context, a novel wavelet-based L-infinite-constrained coding approach for meshes is proposed, which ensures that the maximum error between the vertex positions in the original and decoded meshes is lower than a given upper bound. Furthermore, the proposed system achieves scalability in L-infinite sense, that is, any decoding of the input stream will correspond to a perfectly predictable L-infinite distortion upper bound. An instantiation of the proposed L-infinite-coding approach is demonstrated for MESHGRID, which is a scalable 3D object encoding system, part of MPEG-4 AFX. In this context, the advantages of scalable L-infinite coding over L-2-oriented coding are experimentally demonstrated. One concludes that the proposed L-infinite mesh-coding approach guarantees an upper bound on the local error in the decoded mesh, it enables a fast real-time implementation of the rate allocation, and it preserves all the scalability features and animation capabilities of the employed scalable mesh codec. PMID:20224144
Orthogonality preserving infinite dimensional quadratic stochastic operators
Akın, Hasan; Mukhamedov, Farrukh
2015-09-18
In the present paper, we consider a notion of orthogonal preserving nonlinear operators. We introduce π-Volterra quadratic operators finite and infinite dimensional settings. It is proved that any orthogonal preserving quadratic operator on finite dimensional simplex is π-Volterra quadratic operator. In infinite dimensional setting, we describe all π-Volterra operators in terms orthogonal preserving operators.
Envisioning the Infinite by Projecting Finite Properties
ERIC Educational Resources Information Center
Ely, Robert
2011-01-01
We analyze interviews with 24 post-secondary students as they reason about infinite processes in the context of the tricky Tennis Ball Problem. By metaphorically projecting various properties from the finite states such as counting and indexing, participants envisioned widely varying final states for the infinite process. Depending on which…
Quantum walks with infinite hitting times
Krovi, Hari; Brun, Todd A.
2006-10-15
Hitting times are the average time it takes a walk to reach a given final vertex from a given starting vertex. The hitting time for a classical random walk on a connected graph will always be finite. We show that, by contrast, quantum walks can have infinite hitting times for some initial states. We seek criteria to determine if a given walk on a graph will have infinite hitting times, and find a sufficient condition, which for discrete time quantum walks is that the degeneracy of the evolution operator be greater than the degree of the graph. The set of initial states which give an infinite hitting time form a subspace. The phenomenon of infinite hitting times is in general a consequence of the symmetry of the graph and its automorphism group. Using the irreducible representations of the automorphism group, we derive conditions such that quantum walks defined on this graph must have infinite hitting times for some initial states. In the case of the discrete walk, if this condition is satisfied the walk will have infinite hitting times for any choice of a coin operator, and we give a class of graphs with infinite hitting times for any choice of coin. Hitting times are not very well defined for continuous time quantum walks, but we show that the idea of infinite hitting-time walks naturally extends to the continuous time case as well.
Infinite sets and double binds.
Arden, M
1984-01-01
There have been many attempts to bring psychoanalytical theory up to date. This paper approaches the problem by discussing the work of Gregory Bateson and Ignacio Matte-Blanco, with particular reference to the use made by these authors of Russell's theory of logical types. Bateson's theory of the double bind and Matte-Blanco's bilogic are both based on concepts of logical typing. It is argued that the two theories can be linked by the idea that neurotic symptoms are based on category errors in thinking. Clinical material is presented from the analysis of a middle-aged woman. The intention is to demonstrate that the process of making interpretations can be thought of as revealing errors in thinking. Changes in the patient's inner world are then seen to be the result of clarifying childhood experiences based on category errors. Matte-Blanco's theory of bilogic and infinite experiences is a re-evaluation of the place of the primary process in mental life. It is suggested that a combination of bilogic and double bind theory provides a possibility of reformulating psychoanalytical theory. PMID:6544755
Dual range infinitely variable transmission
Eichenberger, P.
1989-10-31
This patent describes in a transaxle assembly comprising an infinitely variably belt and sheave assembly driving sheave portions and driven sheave portions, a housing assembly enclosing the sheave portions. It includes a torque input shaft coaxially disposed with respect to the driving sheave portions, means for drivably connecting the driving sheave portions and the input shaft; a secondary shaft having an axis in spaced parallel relationship with respect to the torque input shaft. The driven sheave portions being mounted for rotation on the axis of the secondary shaft; a flexible drive member driveable connected to the input sheave portions and the output sheave portions. The flexible drive member engaging the input and output sheave portions at an effective pitch diameter for each sheave portion; fluid pressure servo means for adjustable positioning the sheave portions to effect variations in the effective pitch diameters of the driving sheave portions and the driven sheave portions; a countershaft mounted in spaced parallel dispositions with respect to the secondary shaft, a bearing assembly means for journalling the countershaft in the housing assembly, a high speed range gear train connecting the secondary shaft with the countershaft; fluid pressure operated clutch means for activating and deactivating selectively the high speed range gear train and the low speed range gear train; and planetary forward and reverse means disposed concentrically with respect to the countershaft including clutch means.
Infinite sets and double binds.
Arden, M
1984-01-01
There have been many attempts to bring psychoanalytical theory up to date. This paper approaches the problem by discussing the work of Gregory Bateson and Ignacio Matte-Blanco, with particular reference to the use made by these authors of Russell's theory of logical types. Bateson's theory of the double bind and Matte-Blanco's bilogic are both based on concepts of logical typing. It is argued that the two theories can be linked by the idea that neurotic symptoms are based on category errors in thinking. Clinical material is presented from the analysis of a middle-aged woman. The intention is to demonstrate that the process of making interpretations can be thought of as revealing errors in thinking. Changes in the patient's inner world are then seen to be the result of clarifying childhood experiences based on category errors. Matte-Blanco's theory of bilogic and infinite experiences is a re-evaluation of the place of the primary process in mental life. It is suggested that a combination of bilogic and double bind theory provides a possibility of reformulating psychoanalytical theory.
Infinite resources: the ultimate strategy
Goeller, H.E.; Zucker, A.
1984-02-03
If the author's projections of world demand for nonrenewable materials prove to be reasonably correct, then it seems highly likely that currently economic resources of many important elements will be in inadequate supply by 2100. At the same time, the prospects appear good that resources of more than 30 elements can be made virtually unlimited if sufficient R and D is invested. Eventually a number of elements will undoubtedly become too scarce and expensive to use except for a few vital purposes. However, there is plenty of time before resources of any limited material become completely economically depleted in which to develop adequate substitutes by using more plentiful materials. The ability to tailor new materials to set specifications is advancing rapidly, and our capabilities in this direction should grow with time if R and D in this area is adequately supported. Although a strategy of infinite resources may be difficult to pursue in the face of global political uncertainties, success would mean that future shortages will be at most only transient events and that a stable population of 8.5 billion people will not be imperiled or impoverished by the lack of materials required for civilized life. 20 references, 3 tables.
Subdivisions with infinitely supported mask
NASA Astrophysics Data System (ADS)
Li, Song; Pan, Yali
2008-04-01
In this paper we investigate the convergence of subdivision schemes associated with masks being polynomially decay sequences. Two-scale vector refinement equations are the formwhere the vector of functions [phi]=([phi]1,E..,[phi]r)T is in and is polynomially decay sequence of rxr matrices called refinement mask. Associated with the mask a is a linear operator on given byBy using same methods in [B. Han, R. Q. Jia, Characterization of Riesz bases of wavelets generated from multiresolution analysis, manuscript]; [BE Han, Refinable functions and cascade algorithms in weighted spaces with infinitely supported masks, manuscript]; [R.Q. Jia, Q.T. Jiang, Z.W. Shen, Convergence of cascade algorithms associated with nonhomogeneous refinement equations, Proc. Amer. Math. Soc. 129 (2001) 415-427]; [R.Q. Jia, Convergence of vector subdivision schemes and construction of biorthogonal multiple wavelets, in: Advances in Wavelet, Hong Kong,1997, Springer, Singapore, 1998, pp. 199-227], a characterization of convergence of the sequences in the L2-norm is given, which extends the main results in [R.Q. Jia, S.D. Riemenschneider, D.X. Zhou, Vector subdivision schemes and multiple wavelets, Math. Comp. 67 (1998) 1533-1563] on convergence of the subdivision schemes associated with a finitely supported mask to the case in which mask a is polynomially decay sequence. As an application, we also obtain a characterization of smoothness of solutions of the refinement equation mentioned above for the case r=1.
Crow, Brian S.; Pantazides, Brooke G.; Quiñones-González, Jennifer; Garton, Joshua W.; Carter, Melissa D.; Perez, Jonas W.; Watson, Caroline M.; Tomcik, Dennis J.; Crenshaw, Michael D.; Brewer, Bobby N.; Riches, James R.; Stubbs, Sarah J.; Read, Robert W.; Evans, Ronald A.; Thomas, Jerry D.; Blake, Thomas A.; Johnson, Rudolph C.
2015-01-01
This work describes a new specific, sensitive, and rapid stable isotope dilution method for the simultaneous detection of the organophosphorus nerve agents (OPNAs) tabun (GA), sarin (GB), soman (GD), cyclosarin (GF), VR, VX, and VM adducts to tyrosine (Tyr). Serum, plasma, and lysed whole blood samples (50 µL) were prepared by protein precipitation followed by digestion with Pronase. Specific Tyr adducts were isolated from the digest by a single solid phase extraction (SPE) step, and the analytes were separated by reversed-phase ultra high performance liquid chromatography (UHPLC) gradient elution in less than 2 min. Detection was performed on a triple quadrupole tandem mass spectrometer using time-triggered selected reaction monitoring (SRM) in positive electrospray ionization (ESI) mode. The calibration range was characterized from 0.100–50.0 ng/mL for GB– and VR– Tyr and 0.250–50.0 ng/mL for GA–, GD–, GF–, and VX/VM–Tyr (R2 ≥ 0.995). Inter- and intra-assay precision had coefficients of variation of ≤17 and ≤10%, respectively, and the measured concentration accuracies of spiked samples were within 15% of the targeted value for multiple spiking levels. The limit of detection was calculated to be 0.097, 0.027, 0.018, 0.074, 0.023, and 0.083 ng/mL for GA–, GB–, GD–, GF–, VR–, and VX/VM–Tyr, respectively. A convenience set of 96 serum samples with no known nerve agent exposure was screened and revealed no baseline values or potential interferences. This method provides a simple and highly specific diagnostic tool that may extend the time postevent that a confirmation of nerve agent exposure can be made with confidence. PMID:25286390
Where Infinite Spin Particles are Localizable
NASA Astrophysics Data System (ADS)
Longo, Roberto; Morinelli, Vincenzo; Rehren, Karl-Henning
2016-07-01
Particle states transforming in one of the infinite spin representations of the Poincaré group (as classified by E. Wigner) are consistent with fundamental physical principles, but local fields generating them from the vacuum state cannot exist. While it is known that infinite spin states localized in a spacelike cone are dense in the one-particle space, we show here that the subspace of states localized in any double cone is trivial. This implies that the free field theory associated with infinite spin has no observables localized in bounded regions. In an interacting theory, if the vacuum vector is cyclic for a double cone local algebra, then the theory does not contain infinite spin representations. We also prove that if a Doplicher-Haag-Roberts representation (localized in a double cone) of a local net is covariant under a unitary representation of the Poincaré group containing infinite spin, then it has infinite statistics. These results hold under the natural assumption of the Bisognano-Wichmann property, and we give a counter-example (with continuous particle degeneracy) without this property where the conclusions fail. Our results hold true in any spacetime dimension s + 1 where infinite spin representations exist, namely {s≥ 2}.
Technology Transfer Automated Retrieval System (TEKTRAN)
The availability of deuterium-labeled nicotinic acid makes stable isotope dilution mass spectrometry (SIDMS) coupled with liquid chromatography (LC) an attractive option for the determination of the water-soluble B-vitamin, niacin, in food samples. We have developed a method based on AOAC Peer-Verif...
Wong, W.W.; Cochran, W.J.; Klish, W.J.; Smith, E.O.; Lee, L.S.; Klein, P.D.
1988-01-01
In vivo isotope-fractionation factors were determined for hydrogen and oxygen between plasma water samples and samples of urine, saliva, respiratory water vapor, and carbon dioxide in 20 normal adults. The isotope-fractionation factors ranged from 0.944 to 1.039 for /sup 2/H in breath water vapor and for /sup 18/O in breath CO/sub 2/, respectively. When corrected for isotope fractionation, the /sup 2/H- and /sup 18/O-dilution spaces determined from urine, saliva, respiratory water, and CO/sub 2/ were within -0.10 +/- 1.09 kg (mean +/- SD, n = 60) and 0.04 +/- 0.68 kg (n = 80), respectively, of the values determined from plasma. In the absence of these corrections, we observed a 6% overestimation of /sup 2/H-dilution space and a 1% overestimation of /sup 18/O-dilution space from the use of respiratory water values. A 4% underestimation of the /sup 18/O-dilution space was observed for breath CO/sub 2/ without correction for isotope fractionation.
NASA Astrophysics Data System (ADS)
Akinfiev, Nikolay N.; Plyasunov, Andrey V.
2014-02-01
for gaseous Si(OH)4 were approximated by a function and used in the treatment of data, see Table 1. The fitting procedure to evaluate the parameters of the Akinfiev-Diamond model also included the values of ΔfGo and S° of Si(OH)4 in ideal gas state at standard state conditions.First, to fit the EoS parameters, the dataset for g2∞ (Si(OH)4(aq)) has been generated using accepted experimental data on quartz solubility in water according to the reaction SiO2(quartz) + 2H2O = Si(OH)4(aq), as g2∞(SiOH(aq)(T,P)=g(quartz)(T,P)+2g(HO)(T,P)-RTlnm, where mSi corresponds to the molality of silica in the solution. Thermodynamic properties of quartz were adopted from SUPCRT database (Johnson et al., 1992), while g(H2O)(T, P) was computed using the Hill (1990) and/or Wagner and Pruß (2002) formulations.The fitting procedure was organized as described below. It is known that partial molar properties of dilute solutes close to the critical point of water are governed by the Krichevskii parameter, AKr (Levelt Sengers, 1991). Plyasunov (2012) recommended for Si(OH)4AKr = -190 ± 10 MPa evaluated from the available relevant data. We have used this value as an anchor while fitting. So, the fitting procedure was iterative. After any initial approximation for ξ, values of the a, b parameters of the EoS together with ΔfGo298(g) and So298(g) of Si(OH)4 were determined by a linear regression of the available g2∞ (Si(OH)4(aq)) experimental data. Then the ξ parameter was modified in compliance with the adopted AKr value (Eq. A7), and the fitting cycle was repeated until ξ ceased changing.The finally retrieved values for gaseous Si(OH)4 are ΔfGo298 = -1239.66 ± 1.7 kJ mol-1, So298 = 346.37 ± 3.5 J mol-1 K-1, and the EoS parameters are ξ = -1.8933; a = 0.9285 ± 1.1 cm3 g-1; b = -0.9409 ± 0.97 cm3 K0.5 g-1 (2σ confidence) (Table 1). Evaluated in this work values of ΔfGo298 and So298 for Si(OH)4 in the ideal gas state are very close to the data given in Plyasunov (2011b) on the
Semi-infinite cohomology and string theory.
Frenkel, I B; Garland, H; Zuckerman, G J
1986-11-01
We develop the theory of semi-infinite cohomology of graded Lie algebras first introduced by Feigin. We show that the relative semi-infinite cohomology has a structure analogous to that of the de Rham cohomology in Kähler geometry. We prove a vanishing theorem for a special class of modules, and we apply our results to the case of the Virasoro algebra and the Fock module. In this case the zero cohomology is identified as the physical subspace of the Fock module and the no-ghost theorem follows. We reveal the profound relation of semi-infinite cohomology theory to the gauge-invariant free string theory constructed by Banks and Peskin. We then indicate the connection between gauge-invariant interacting string theories and the geometric realizations of the infinite-dimensional Lie algebras.
Understanding the behaviour of infinite ladder circuits
NASA Astrophysics Data System (ADS)
Ucak, C.; Yegin, K.
2008-11-01
Infinite ladder circuits are often encountered in undergraduate electrical engineering and physics curricula when dealing with series and parallel combination of impedances, as a part of filter design or wave propagation on transmission lines. The input impedance of such infinite ladder circuits is derived by assuming that the input impedance does not change when a new block of impedance is added. However, the impedance derived from this assumption may lead to incorrect conclusions if it is not treated carefully. Sometimes, in the literature, the input impedance behaviour of infinite ladder circuits is referred to as a paradox, leaving students and educators in doubt. This study intends to clarify this confusion and help to better comprehend the behaviour of the input impedance of infinite ladder circuits.
Helium dilution refrigeration system
Roach, Patrick R.; Gray, Kenneth E.
1988-01-01
A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.
Helium dilution refrigeration system
Roach, P.R.; Gray, K.E.
1988-09-13
A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.
Dilution, Concentration, and Flotation
ERIC Educational Resources Information Center
Liang, Ling; Schmuckler, Joseph S.
2004-01-01
As both classroom teaching practice and literature show, many students have difficulties learning science concepts such as density. Here are some investigations that identify the relationship between density and floating through experimenting with successive dilution of a liquid, or the systematic change of concentration of a saltwater solution.…
Maximum independent set on diluted triangular lattices
NASA Astrophysics Data System (ADS)
Fay, C. W., IV; Liu, J. W.; Duxbury, P. M.
2006-05-01
Core percolation and maximum independent set on random graphs have recently been characterized using the methods of statistical physics. Here we present a statistical physics study of these problems on bond diluted triangular lattices. Core percolation critical behavior is found to be consistent with the standard percolation values, though there are strong finite size effects. A transfer matrix method is developed and applied to find accurate values of the density and degeneracy of the maximum independent set on lattices of limited width but large length. An extrapolation of these results to the infinite lattice limit yields high precision results, which are tabulated. These results are compared to results found using both vertex based and edge based local probability recursion algorithms, which have proven useful in the analysis of hard computational problems, such as the satisfiability problem.
Bulk Viscosity and Conformal Symmetry Breaking in the Dilute Fermi Gas near Unitarity
NASA Astrophysics Data System (ADS)
Dusling, Kevin; Schäfer, Thomas
2013-09-01
The dilute Fermi gas at unitarity is scale invariant and its bulk viscosity vanishes. We compute, in the high temperature limit, the leading contribution to the bulk viscosity when the scattering length is not infinite. A measure of scale breaking is provided by the ratio (P-2/3E)/P, where P is the pressure and E is the energy density. At high temperature this ratio scales as zλ/a, where z is the fugacity, λ is the thermal wavelength, and a is the scattering length. We show that the bulk viscosity ζ scales as the second power of this parameter, ζ˜(zλ/a)2λ-3.
Bulk viscosity and conformal symmetry breaking in the dilute Fermi gas near unitarity.
Dusling, Kevin; Schäfer, Thomas
2013-09-20
The dilute Fermi gas at unitarity is scale invariant and its bulk viscosity vanishes. We compute, in the high temperature limit, the leading contribution to the bulk viscosity when the scattering length is not infinite. A measure of scale breaking is provided by the ratio (P-2πħ/3ε)/P, where P is the pressure and E is the energy density. At high temperature this ratio scales as zλ/a, where z is the fugacity, λ is the thermal wavelength, and a is the scattering length. We show that the bulk viscosity ζ scales as the second power of this parameter, ζ~(zλ/a)(2)λ(-3).
Calibration graphs in isotope dilution mass spectrometry.
Pagliano, Enea; Mester, Zoltán; Meija, Juris
2015-10-01
Isotope-based quantitation is routinely employed in chemical measurements. Whereas most analysts seek for methods with linear theoretical response functions, a unique feature that distinguishes isotope dilution from many other analytical methods is the inherent possibility for a nonlinear theoretical response curve. Most implementations of isotope dilution calibration today either eliminate the nonlinearity by employing internal standards with markedly different molecular weight or they employ empirical polynomial fits. Here we show that the exact curvature of any isotope dilution curve can be obtained from three-parameter rational function, y = f(q) = (a0 + a1q)/(1 + a2q), known as the Padé[1,1] approximant. The use of this function allows eliminating an unnecessary source of error in isotope dilution analysis when faced with nonlinear calibration curves. In addition, fitting with Padé model can be done using linear least squares.
Depletion force in the infinite-dilution limit in a solvent of nonadditive hard spheres.
Fantoni, Riccardo; Santos, Andrés
2014-06-28
The mutual entropic depletion force felt by two solute "big" hard spheres immersed in a binary mixture solvent of nonadditive "small" hard spheres is calculated as a function of the surface-to-surface distance by means of canonical Monte Carlo simulations and through a recently proposed rational-function approximation [R. Fantoni and A. Santos, Phys. Rev. E 84, 041201 (2011)]. Four representative scenarios are investigated: symmetric solute particles and the limit where one of the two solute spheres becomes a planar hard wall, in both cases with symmetric and asymmetric solvents. In all cases, the influence on the depletion force due to the nonadditivity in the solvent is determined in the mixed state. Comparison between results from the theoretical approximation and from the simulation shows a good agreement for surface-to-surface distances greater than the smallest solvent diameter.
Equilibrium and kinetics of adsorption of Freon-12 at infinite dilution
Golden, T.C.; Sircar, S. )
1994-06-01
Equilibrium and kinetic data for adsorption of trace CF[sub 2]Cl[sub 2] (Freon-12) from various carrier gased on BPL activated carbon are reported. Coadsorption of the bulk carrier gas can severely reduce the equilibrium adsorption capacity and adsorptive mass-transfer coefficient of strongly adsorbed CF[sub 2]Cl[sub 2]. The difference in size between CF[sub 2]Cl[sub 2] and the bulk carrier gas molecules plays a major role in establishing the binary or multicomponent equilibrium adsorption properties. The multisite (singe and multicomponent) Langmuir model, which accounts for differences in adsorbate sizes, provides a reasonable framework for describing the size effects. The adsorptive mass transfer of CF[sub 2]Cl[sub 2] under the experimental conditions investigated is dominated by surface diffusion into the pores of the activated carbon. The surface diffusivity is a strong function of the extent of coverage and strength of adsorption of the bulk components.
Automatic dilution gaging of rapidly varying flow
Duerk, M.D.
1983-01-01
The analysis showed that the discharges measured by dye-dilution techniques were generally within ± 10 percent of the discharges determined from ratings established by current-meter measurements. Larger differences were noted at the start of and on the rising limb of four hydrographs. Of the 20 storms monitored, dilution measurements on 17 were of acceptable accuracy. Peak discharges from the open-channel site ranged from 0 to 12 percent departures from the existing rating whereas the comparison of peak discharge at the storm sewer site ranged from 0 to 5 percent departures from the existing rating.
Minimal Coital Dilution in Accra, Ghana
Jenness, Samuel M.; Biney, Adriana A. E.; Ampofo, William Kwabena; Dodoo, F. Nii-Amoo; Cassels, Susan
2015-01-01
Background Coital dilution, the reduction in the coital frequency per partner when an additional ongoing partner is added, may reduce the transmission potential of partnership concurrency for HIV and other sexually transmitted infections. Empirical estimates of dilution, especially dilution of sexual acts unprotected by condoms, are needed to inform prevention research. Methods Sexually active adults in Accra, Ghana were recruited in a multi-stage household probability sample. Degree (number of ongoing partners), total acts, and unprotected acts were measured retrospectively for each month in the past year through an event-history calendar. Random effects negative binomial models estimated the association between degree and coital frequency. Results Compared to person-months with a single partner (monogamy), 2.06 times as many total acts and 1.94 times as many unprotected acts occurred in months with 2 partners. In months with 3 partners, 2.90 times as many total acts and 2.39 times as many unprotected acts occurred compared to monogamous months. Total acts but not unprotected acts also declined with partnership duration. Conclusions No dilution was observed for total acts with up to three concurrent partners, but a small amount of dilution was observed for unprotected acts for months with multiple concurrencies. This suggests moderate selective condom use in months with multiple concurrencies. The implications of the observed dilution for future HIV transmission must be investigated with mathematical models. PMID:25622062
Gluconeogenesis from labeled carbon: estimating isotope dilution
Kelleher, J.K.
1986-03-01
To estimate the rate of gluconeogenesis from steady-state incorporation of labeled 3-carbon precursors into glucose, isotope dilution must be considered so that the rate of labeling of glucose can be quantitatively converted to the rate of gluconeogenesis. An expression for the value of this isotope dilution can be derived using mathematical techniques and a model of the tricarboxylic acid (TCA) cycle. The present investigation employs a more complex model than that used in previous studies. This model includes the following pathways that may affect the correction for isotope dilution: 1) flux of 3-carbon precursor to the oxaloacetate pool via acetyl-CoA and the TCA cycle; 2) flux of 4- or 5-carbon compounds into the TCA cycle; 3) reversible flux between oxaloacetate (OAA) and pyruvate and between OAA and fumarate; 4) incomplete equilibrium between OAA pools; and 5) isotope dilution of 3-carbon tracers between the experimentally measured pool and the precursor for the TCA-cycle OAA pool. Experimental tests are outlined which investigators can use to determine whether these pathways are significant in a specific steady-state system. The study indicated that flux through these five pathways can significantly affect the correction for isotope dilution. To correct for the effects of these pathways an alternative method for calculating isotope dilution is proposed using citrate to relate the specific activities of acetyl-CoA and OAA.
Intrinsic diffusion coefficients and the vacancy flow factor in Dilute Cu-Zn Alloys
NASA Astrophysics Data System (ADS)
Hoshino, Kazutomo; Iijima, Yoshiaki; Hirano, Ken-Ichi
1982-07-01
Interdiffusion coefficients in copper-rich copper-zinc solid solutions containing up to 8 at. pct of Zn at 1168 K have been determined by Matano's analysis using semi-infinite diffusion couples consisting of pure copper and Cu-Zn alloys with Kirkendall markers. From the marker shift and Darken's relation, intrinsic diffusion coefficients, DZn and DCu, in the alloys containing 3.2 and 4.7 at. pct of Zn have been determined. Further, using thin plate couples, DZn and DCu in Cu alloys containing 0.9, 2.3, 3.5, and 4.6 at. pct of Zn at 1168 K have been determined by Heumann's method. The ratio of the intrinsic diffusion coefficients, DZn/DCu, has been found to be about two for all the compositions examined. Using the values of the intrinsic diffusion coefficient of copper at infinite dilution of zinc obtained by extrapolating the concentration dependence of DCu, and the self- and impurity diffusion coefficients in pure copper, the vacancy flow factor has been estimated to be - 0.22-0.15 +0.06 at 1168 K. By combining this value of the vacancy flow factor with the solute enhancement factor of solvent diffusion determined by Peterson and Rothman, the correlation factor for impurity diffusion of Zn in Cu at 1168 K has been evaluated to be 0.5, which is in good agreement with the value of 0.47 determined by Peterson and Rothman based on the isotope effect measurement.
Zakry, Fitri Abdul Aziz; Shamsuddin, Zulkifli H.; Rahim, Khairuddin Abdul; Zakaria, Zin Zawawi; Rahim, Anuar Abdul
2012-01-01
There are increasing applications of diazotrophic rhizobacteria in the sustainable agriculture system. A field experiment on young immature oil palm was conducted to quantify the uptake of N derived from N2 fixation by the diazotroph Bacillus sphaericus strain UPMB-10, using the 15N isotope dilution method. Eight months after 15N application, young immature oil palms that received 67% of standard N fertilizer application together with B. sphaericus inoculation had significantly lower 15N enrichment than uninoculated palms that received similar N fertilizers. The dilution of labeled N served as a marker for the occurrence of biological N2 fixation. The proportion of N uptake that was derived from the atmosphere was estimated as 63% on the whole plant basis. The inoculation process increased the N and dry matter yields of the palm leaflets and rachis significantly. Field planting of young, immature oil palm in soil inoculated with B. sphaericus UPMB-10 might mitigate inorganic fertilizer-N application through supplementation by biological nitrogen fixation. This could be a new and important source of nitrogen biofertilizer in the early phase of oil palm cultivation in the field. PMID:22446306
NASA Astrophysics Data System (ADS)
Macintosh Wilson, Alistair
1996-01-01
A conversation between Euclid and the ghost of Socrates. . . the paths of the moon and the sun charted by the stone-builders of ancient Europe. . .the Greek ideal of the golden mean by which they measured beauty. . . Combining historical fact with a retelling of ancient myths and legends, this lively and engaging book describes the historical, religious and geographical background that gave rise to mathematics in ancient Egypt, Babylon, China, Greece, India, and the Arab world. Each chapter contains a case study where mathematics is applied to the problems of the era, including the area of triangles and volume of the Egyptian pyramids; the Babylonian sexagesimal number system and our present measure of space and time which grew out of it; the use of the abacus and remainder theory in China; the invention of trigonometry by Arab mathematicians; and the solution of quadratic equations by completing the square developed in India. These insightful commentaries will give mathematicians and general historians a better understanding of why and how mathematics arose from the problems of everyday life, while the author's easy, accessible writing style will open fascinating chapters in the history of mathematics to a wide audience of general readers.
Kress, Michael; Meissner, Dieane; Kaiser, Patricia; Hanke, Rainer; Wood, William Graham
2002-01-01
A method is described which uses a combination of gas chromatography and isotope dilution-mass spectrometry (GC-IDMS) to determine the concentration of theophylline (1,3-dimethyl xanthine) in human plasma or serum samples. The effects of similar substituted xanthines - namely theobromine (3,7-dimethyl xanthine), paraxanthine (1,7-dimethyl xanthine) 1,3-dimethyl-7-(2-hydroxyethyl) xanthine (internal standard HPLC) and caffeine (1,3,7-trimethyl xanthine) were tested to confirm the specificity of the method. The derivatisation of all xanthines was performed with N-methyl-N-trimethylsilyl trifluroacetamide (MSTFA). The internal standard used was 2-(13)C ,1,3-(15)N2-theophylline. The extraction and derivatisation procedures were examined in detail and optimised stepwise during the development of the method. High-performance liquid chromatography (HPLC) was used for comparison.
A Planar Calculus for Infinite Index Subfactors
NASA Astrophysics Data System (ADS)
Penneys, David
2013-05-01
We develop an analog of Jones' planar calculus for II 1-factor bimodules with arbitrary left and right von Neumann dimension. We generalize to bimodules Burns' results on rotations and extremality for infinite index subfactors. These results are obtained without Jones' basic construction and the resulting Jones projections.
On infinite-dimensional state spaces
Fritz, Tobias
2013-05-15
It is well known that the canonical commutation relation [x, p]=i can be realized only on an infinite-dimensional Hilbert space. While any finite set of experimental data can also be explained in terms of a finite-dimensional Hilbert space by approximating the commutation relation, Occam's razor prefers the infinite-dimensional model in which [x, p]=i holds on the nose. This reasoning one will necessarily have to make in any approach which tries to detect the infinite-dimensionality. One drawback of using the canonical commutation relation for this purpose is that it has unclear operational meaning. Here, we identify an operationally well-defined context from which an analogous conclusion can be drawn: if two unitary transformations U, V on a quantum system satisfy the relation V{sup -1}U{sup 2}V=U{sup 3}, then finite-dimensionality entails the relation UV{sup -1}UV=V{sup -1}UVU; this implication strongly fails in some infinite-dimensional realizations. This is a result from combinatorial group theory for which we give a new proof. This proof adapts to the consideration of cases where the assumed relation V{sup -1}U{sup 2}V=U{sup 3} holds only up to {epsilon} and then yields a lower bound on the dimension.
Infinite Sums of M-Bonacci Numbers
ERIC Educational Resources Information Center
A-iru, Muniru A.
2009-01-01
In this note, we construct infinite series using M-bonacci numbers in a manner similar to that used in previous studies and investigate the convergence of the series to an integer. Our results generalize the ones obtained for Fibonacci numbers.
Convex aggregative modelling of infinite memory nonlinear systems
NASA Astrophysics Data System (ADS)
Wachel, Paweł
2016-08-01
The convex aggregation technique is applied for modelling general class of nonlinear systems with unknown structure and infinite memory. The finite sample size properties of the algorithm are formally established and compared to the standard least-squares counterpart of the method. The proposed algorithm demonstrates its advantages when the a-priori knowledge and the measurement data are both scarce, that is, when the information about the actual system structure is unknown or uncertain and the measurement set is small and disturbed by a noise. Numerical experiments illustrate application and practical benefits of the method for various nonlinear systems.
Ebulliometers for measuring the thermodynamic properties of fluids and fluid mixtures
Weber, L.A.; Silva, A.M.
1994-09-01
The design and operation of two ebulliometers is described. One is constructed of glass and is used for measuring vapor pressures of fluids at low reduced temperatures and pressures. The other is constructed of metal. It can be used for vapor pressure measurements, and also for the study of fluid mixture thermodynamics through the determination of the activity coefficients at infinite dilution. The advantages and potential problems associated with ebulliometers are described, and typical results are given for the properties of alternative refrigerants.
Dispersion serial dilution methods using the gradient diluter device.
Walling, Leslie; Schulz, Craig; Johnson, Michael
2012-12-01
A solute aspirated into a prefilled tube of diluent undergoes a dilution effect known as dispersion. Traditionally the effects of dispersion have been considered a negative consequence of using liquid-filled fixed-tip liquid handlers. We present a novel device and technique that utilizes the effects of dispersion to the benefit of making dilutions. The device known as the Gradient Diluter extends the dilution range of practical serial dilutions to six orders of magnitude in final volumes as low as 10 μL. Presented are the device, dispersion methods, and validation tests using fluorescence detection of sulforhodamine and the high-performance liquid chromatography/ultraviolet detection of furosemide. In addition, a T-cell inhibition assay of a relevant downstream protein is used to demonstrate IC(50) curves made with the Gradient Diluter compare favorably with those generated by hand.
Identification of cardiovascular dilution systems by contrast ultrasound.
Mischi, Massimo; Jansen, Annemieke H M; Korsten, Hendrikus H M
2007-03-01
Indicator dilution techniques permit accurate measurements of important cardiovascular parameters, such as pulmonary blood volume (PBV) and ejection fraction (EF). However, their use is limited by the need for central catheterization. Contrast ultrasonography allows overcoming this problem. PBV and EF can be measured by a dilution system identification algorithm after detection of multiple dilution curves by an ultrasound scanner. In this paper, we present a system identification method that exploits the a priori knowledge on the dilution system and finds the optimum parameters for the parametric model representing the dilution system impulse response. No subsequent model interpolation is needed. Volume measurements show accurate in-vitro results and clinical feasibility, while 50 EF measurements in patients show a 0.88 correlation coefficient with echocardiographic biplane estimates. In conclusion, adding a priori knowledge to the system identification algorithm leads to increased accuracy and robustness of the method for PBV and EF measurements.
Diluted magnetic semiconductors
NASA Astrophysics Data System (ADS)
Anderson, James R.
1990-03-01
Growth and physical properties of diluted magnetic semiconductors (DMS) were investigated. Growth included Bridgman, solid state recrystallization, and liquid phase epitaxy of Mercury(1-x)Manganese(x)Telluride and Mercury(1-x-y)Manganese(x)Cadmium(y)Telluride. Very uniform crystals were produced by solid state recrystallization. Physical properties studied included magnetization, optical response, and magnetotransport. From magnetization, the exchange interactions among magnetic ions have been deduced. Modulated spectroscopy gave details of the electronic structure of DMS and the quality of the material was indicated by the line widths. Magnetotransport, carried out in some cases to 30 T, showed a large negative magnetoresistance and subsequent increase. The Hg(1-x-y)Mn(x)Cd(y)Te has considerable promise for avalanche photodiodes between 1.2 and 1.8 micrometers.
NASA Technical Reports Server (NTRS)
Srinivasan, R.; Coleman, E.; Johnson, K.
1984-01-01
Parametric tests were conducted to quantify the mixing of opposed rows of jets (two-sided injection) in a confined cross flow. Results show that jet penetrations for two sided injections are less than that for single-sided injections, but the jet spreading rates are faster for a given momentum ratio and orifice plate. Flow area convergence generally enhances mixing. Mixing characteristics with asymmetric and symmetric convergence are similar. For constant momentum ratio, the optimum S/H(0) with in-line injections is one half the optimum value for single sided injections. For staggered injections, the optimum S/H(0) is twice the optimum value for single-sided injection. The correlations developed predicted the temperature distributions within first order accuracy and provide a useful tool for predicting jet trajectory and temperature profiles in the dilution zone with two-sided injections.
Scaling of Greenwood Peierls conductance on a diluted square lattice
NASA Astrophysics Data System (ADS)
Schwalm, William; Schmitz, Albert
The modified rectangle lattice of Dhar is a bond-diluted square lattice. The structure is self-similar and finitely ramified, like a fractal. Nevertheless certain discrete Schrödinger equation Green functions for the modified rectangle are known in closed form in the infinite lattice limit and the spectrum is continuous. By standard transfer matrix renormalization methods we present a study scaling properties of the Greenwood Peierls conductance distribution across the lattice with one dimensional lead wires attached as a function of lattice size and of additional disorder of several types.
Statistical inference for serial dilution assay data.
Lee, M L; Whitmore, G A
1999-12-01
Serial dilution assays are widely employed for estimating substance concentrations and minimum inhibitory concentrations. The Poisson-Bernoulli model for such assays is appropriate for count data but not for continuous measurements that are encountered in applications involving substance concentrations. This paper presents practical inference methods based on a log-normal model and illustrates these methods using a case application involving bacterial toxins.
Sulfuric Acid and Water: Paradoxes of Dilution
ERIC Educational Resources Information Center
Leenson, I. A.
2004-01-01
On equilibrium properties of aqueous solutions of sulfuric acid, Julius Thomsen has marked that the heat evolved on diluting liquid sulfuric acid with water is a continuous function of the water used, and excluded absolutely the acceptance of definite hydrates as existing in the solution. Information about thermochemical measurement, a discussion…
Mädler, Stefanie; Todd, Aaron; Skip Kingston, H M; Pamuku, Matt; Sun, Fengrong; Tat, Cindy; Tooley, Robert J; Switzer, Teresa A; Furdui, Vasile I
2016-08-15
The reliable analysis of highly toxic hexavalent chromium, Cr(VI), at ultra-trace levels remains challenging, given its easy conversion to non-toxic trivalent chromium. This work demonstrates a novel analytical method to quantify Cr(VI) at low ngL(-1) concentration levels in environmental water samples by using speciated isotope dilution (SID) analysis and double-spiking with Cr(III) and Cr(VI) enriched for different isotopes. Ion chromatography tandem mass spectrometry (IC-MS/MS) was used for the analysis of Cr(VI) as HCrO4(-) → CrO3(-). Whereas the classical linear multipoint calibration (MPC) curve approach obtained a method detection limit (MDL) of 7ngL(-1) Cr(VI), the modified SID-MS method adapted from U. S. EPA 6800 allowed for the quantification of Cr(VI) with an MDL of 2ngL(-1) and provided results corrected for Cr(VI) loss occurred after sample collection. The adapted SID-MS approach proved to yield more accurate and precise results than the MPC method, allowed for compensation of Cr(VI) reduction during sample transportation and storage while eliminating the need for frequent external calibration. The developed method is a complementary tool to routinely used inductively-coupled plasma (ICP) MS and circumvents typically experienced interferences.
Moore, B.D.; Kobza, J.; Seemann, J.R. )
1991-05-01
The level of 2-carboxyarabinitol 1-phosphate (CA1P) in leaves of 12 species was determined by an isotope dilution assay. {sup 14}C-labeled standard was synthesized from (2-{sup 14}C)carboxyarabinitol 1,5-bisphosphate using acid phosphatase, and was added at the initial point of leaf extraction. Leaf CA1P was purified and its specific activity determined. CA1P was found in dark-treated leaves of all species examined, including spinach (Spinacea oleracea), wheat (Triticum aestivum), Arabidopsis thaliana, and maize (Zea mays). The highest amounts were found in bean (Phaseolus vulgaris) and petunia (Petunia hybrida), which had 1.5 to 1.8 moles CA1P per mole ribulose 1,5-bisphosphate carboxylase catalytic sites. Most species had intermediate amounts of CA1P (0.2 to 0.8 mole CA1P per mole catalytic sites). Such intermediate to high levels of CA1P support the hypothesis that CA1P functions in many species as a light-dependent regulator of ribulose 1,5-bisphosphate carboxylase activity and whole leaf photosynthetic CO{sub 2} assimilation. However, CA1P levels in spinach, wheat, and A. thaliana were particularly low (less than 0.09 mole CA1P per mole catalytic sites). In such species, CA1P does not likely have a significant role in regulating ribulose 1,5-bisphosphate carboxylase activity, but could have a different physiological role.
A Stochastic Tikhonov Theorem in Infinite Dimensions
Buckdahn, Rainer Guatteri, Giuseppina
2006-03-15
The present paper studies the problem of singular perturbation in the infinite-dimensional framework and gives a Hilbert-space-valued stochastic version of the Tikhonov theorem. We consider a nonlinear system of Hilbert-space-valued equations for a 'slow' and a 'fast' variable; the system is strongly coupled and driven by linear unbounded operators generating a C{sub 0}-semigroup and independent cylindrical Brownian motions. Under well-established assumptions to guarantee the existence and uniqueness of mild solutions, we deduce the required stability of the system from a dissipativity condition on the drift of the fast variable. We avoid differentiability assumptions on the coefficients which would be unnatural in the infinite-dimensional framework.
Quark ensembles with the infinite correlation length
Zinov’ev, G. M.; Molodtsov, S. V.
2015-01-15
A number of exactly integrable (quark) models of quantum field theory with the infinite correlation length have been considered. It has been shown that the standard vacuum quark ensemble—Dirac sea (in the case of the space-time dimension higher than three)—is unstable because of the strong degeneracy of a state, which is due to the character of the energy distribution. When the momentum cutoff parameter tends to infinity, the distribution becomes infinitely narrow, leading to large (unlimited) fluctuations. Various vacuum ensembles—Dirac sea, neutral ensemble, color superconductor, and BCS state—have been compared. In the case of the color interaction between quarks, the BCS state has been certainly chosen as the ground state of the quark ensemble.
Gauge fields and infinite chains of dualities
NASA Astrophysics Data System (ADS)
Boulanger, Nicolas; Sundell, Per; West, Peter
2015-09-01
We show that the particle states of Maxwell's theory, in D dimensions, can be represented in an infinite number of ways by using different gauge fields. Using this result we formulate the dynamics in terms of an infinite set of duality relations which are first order in space-time derivatives. We derive a similar result for the three form in eleven dimensions where such a possibility was first observed in the context of E 11. We also give an action formulation for some of the gauge fields. In this paper we give a pedagogical account of the Lorentz and gauge covariant formulation of the irreducible representations of the Poincaré group, used previously in higher spin theories, as this plays a key role in our constructions. It is clear that our results can be generalised to any particle.
Infinitely many singular interactions on noncompact manifolds
Kaynak, Burak Tevfik Turgut, O. Teoman
2015-05-15
We show that the ground state energy is bounded from below when there are infinitely many attractive delta function potentials placed in arbitrary locations, while all being separated at least by a minimum distance, on two dimensional non-compact manifold. To facilitate the reading of the paper, we first present the arguments in the setting of Cartan–Hadamard manifolds and then subsequently discuss the general case. For this purpose, we employ the heat kernel techniques as well as some comparison theorems of Riemannian geometry, thus generalizing the arguments in the flat case following the approach presented in Albeverio et al. (2004). - Highlights: • Schrödinger-operator for infinitely many singular interactions on noncompact manifolds. • Proof of the finiteness of the ground-state energy.
The infinite hidden Markov random field model.
Chatzis, Sotirios P; Tsechpenakis, Gabriel
2010-06-01
Hidden Markov random field (HMRF) models are widely used for image segmentation, as they appear naturally in problems where a spatially constrained clustering scheme is asked for. A major limitation of HMRF models concerns the automatic selection of the proper number of their states, i.e., the number of region clusters derived by the image segmentation procedure. Existing methods, including likelihood- or entropy-based criteria, and reversible Markov chain Monte Carlo methods, usually tend to yield noisy model size estimates while imposing heavy computational requirements. Recently, Dirichlet process (DP, infinite) mixture models have emerged in the cornerstone of nonparametric Bayesian statistics as promising candidates for clustering applications where the number of clusters is unknown a priori; infinite mixture models based on the original DP or spatially constrained variants of it have been applied in unsupervised image segmentation applications showing promising results. Under this motivation, to resolve the aforementioned issues of HMRF models, in this paper, we introduce a nonparametric Bayesian formulation for the HMRF model, the infinite HMRF model, formulated on the basis of a joint Dirichlet process mixture (DPM) and Markov random field (MRF) construction. We derive an efficient variational Bayesian inference algorithm for the proposed model, and we experimentally demonstrate its advantages over competing methodologies.
Variational Infinite Hidden Conditional Random Fields.
Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja; Ghahramani, Zoubin
2015-09-01
Hidden conditional random fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An Infinite hidden conditional random field is a hidden conditional random field with a countably infinite number of hidden states, which rids us not only of the necessity to specify a priori a fixed number of hidden states available but also of the problem of overfitting. Markov chain Monte Carlo (MCMC) sampling algorithms are often employed for inference in such models. However, convergence of such algorithms is rather difficult to verify, and as the complexity of the task at hand increases the computational cost of such algorithms often becomes prohibitive. These limitations can be overcome by variational techniques. In this paper, we present a generalized framework for infinite HCRF models, and a novel variational inference approach on a model based on coupled Dirichlet Process Mixtures, the HCRF-DPM. We show that the variational HCRF-DPM is able to converge to a correct number of represented hidden states, and performs as well as the best parametric HCRFs-chosen via cross-validation-for the difficult tasks of recognizing instances of agreement, disagreement, and pain in audiovisual sequences. PMID:26353136
A motif for infinite metal atom wires.
Yin, Xi; Warren, Steven A; Pan, Yung-Tin; Tsao, Kai-Chieh; Gray, Danielle L; Bertke, Jeffery; Yang, Hong
2014-12-15
A new motif for infinite metal atom wires with tunable compositions and properties is developed based on the connection between metal paddlewheel and square planar complex moieties. Two infinite Pd chain compounds, [Pd4(CO)4(OAc)4Pd(acac)2] 1 and [Pd4(CO)4(TFA)4Pd(acac)2] 2, and an infinite Pd-Pt heterometallic chain compound, [Pd4(CO)4(OAc)4Pt(acac)2] 3, are identified by single-crystal X-ray diffraction analysis. In these new structures, the paddlewheel moiety is a Pd four-membered ring coordinated by bridging carboxylic ligands and μ2 carbonyl ligands. The planar moiety is either Pd(acac)2 or Pt(acac)2 (acac = acetylacetonate). These moieties are connected by metallophilic interactions. The results showed that these one-dimensional metal wire compounds have photoluminescent properties that are tunable by changing ligands and metal ions. 3 can also serve as a single source precursor for making Pd4Pt bimetallic nanostructures with precise control of metal composition.
Scan blindness in infinite phased arrays of printed dipoles
NASA Technical Reports Server (NTRS)
Pozar, D. M.; Schaubert, D. H.
1984-01-01
A comprehensive study of infinite phased arrays of printed dipole antennas is presented, with emphasis on the scan blindness phenomenon. A rigorous and efficient moment method procedure is used to calculate the array impedance versus scan angle. Data are presented for the input reflection coefficient for various element spacings and substrate parameters. A simple theory, based on coupling from Floquet modes to surface wave modes on the substrate, is shown to predict the occurrence of scan blindness. Measurements from a waveguide simulator of a blindness condition confirm the theory.
NASA Technical Reports Server (NTRS)
Passman, Stephen L.
1989-01-01
Generally, two types of theory are used to describe the field equations for suspensions. The so-called postulated equations are based on the kinetic theory of mixtures, which logically should give reasonable equations for solutions. The basis for the use of such theory for suspensions is tenuous, though it at least gives a logical path for mathematical arguments. It has the disadvantage that it leads to a system of equations which is underdetermined, in a sense that can be made precise. On the other hand, the so-called averaging theory starts with a determined system, but the very process of averaging renders the resulting system underdetermined. A third type of theory is proposed in which the kinetic theory of gases is used to motivate continuum equations for the suspended particles. This entails an interpretation of the stress in the particles that is different from the usual one. Classical theory is used to describe the motion of the suspending medium. The result is a determined system for a dilute suspension. Extension of the theory to more concentrated systems is discussed.
Supersolids: Solids Having Finite Volume and Infinite Surfaces.
ERIC Educational Resources Information Center
Love, William P.
1989-01-01
Supersolids furnish an ideal introduction to the calculus topic of infinite series, and are useful for combining that topic with integration. Five examples of supersolids are presented, four requiring only a few basic properties of infinite series and one requiring a number of integration principles as well as infinite series. (MNS)
Thermodynamics of a dilute XX chain in a field
NASA Astrophysics Data System (ADS)
Timonin, P. N.
2016-06-01
Gapless phases in ground states of low-dimensional quantum spin systems are rather ubiquitous. Their peculiarity is a remarkable sensitivity to external perturbations due to permanent criticality of such phases manifested by a slow (power-low) decay of pair correlations and the divergence of the corresponding susceptibility. A strong influence of various defects on the properties of the system in such a phase can then be expected. Here, we consider the influence of vacancies on the thermodynamics of the simplest quantum model with a gapless phase, the isotropic spin-1/2 XX chain. The existence of the exact solution of this model gives a unique opportunity to describe in detail the dramatic effect of dilution on the gapless phase—the appearance of an infinite series of quantum phase transitions resulting from level crossing under the variation of a longitudinal magnetic field. We calculate the jumps in the field dependences of the ground-state longitudinal magnetization, susceptibility, entropy, and specific heat appearing at these transitions and show that they result in a highly nonlinear temperature dependence of these parameters at low T. Also, the effect of enhancement of the magnetization and longitudinal correlations in the dilute chain is established. The changes of the pair spin correlators under dilution are also analyzed. The universality of the mechanism of the quantum transition generation suggests that similar effects of dilution can also be expected in gapless phases of other low-dimensional quantum spin systems.
Crow, Brian S; Quiñones-González, Jennifer; Pantazides, Brooke G; Perez, Jonas W; Winkeljohn, W Rucks; Garton, Joshua W; Thomas, Jerry D; Blake, Thomas A; Johnson, Rudolph C
2016-05-01
Chlorine is a public health concern and potential threat due to its high reactivity, ease and scale of production, widespread industrial use, bulk transportation, massive stockpiles and history as a chemical weapon. This work describes a new, sensitive and rapid stable isotope dilution method for the retrospective detection and quantitation of two chlorine adducts. The biomarkers 3-chlorotyrosine (Cl-Tyr) and 3,5-dichlorotyrosine (Cl2-Tyr) were isolated from the pronase digest of chlorine exposed whole blood, serum or plasma by solid-phase extraction (SPE), separated by reversed-phase HPLC and detected by tandem mass spectrometry (MS-MS). The calibration range is 2.50-1,000 ng/mL (R2 ≥ 0.998) with a lowest reportable limit (LRL) of 2.50 ng/mL for both analytes, an accuracy of ≥93% and an LOD of 0.443 ng/mL for Cl-Tyr and 0.396 ng/mL for Cl2-Tyr. Inter- and intra-day precision of quality control samples had coefficients of variation of ≤10% and ≤7.0%, respectively. Blood and serum samples from 200 healthy individuals and 175 individuals with chronic inflammatory disease were analyzed using this method to assess background levels of chlorinated tyrosine adducts. Results from patients with no known inflammatory disease history (healthy) showed baseline levels of
Triton,... electron,... cosmon,...: An infinite regression?
Dehmelt, H
1989-11-01
I propose an elementary particle model in which the simplest near-Dirac particles triton, proton, and electron are members of the three top layers of a bottomless stack. Each particle is a composite of three particles from the next layer below in an infinite regression approaching Dirac point particles. The cosmon, an immensely heavy lower layer subquark, is the elementary particle. The world-atom, a tightly bound cosmon/anticosmon pair of zero relativistic total mass, arose from the nothing state in a quantum jump. Rapid decay of the pair launched the big bang and created the universe. PMID:16594084
Infinite Maxwell fisheye inside a finite circle
NASA Astrophysics Data System (ADS)
Liu, Yangjié; Chen, Huanyang
2015-12-01
This manuscript proposes a two-dimensional heterogeneous imaging medium composed of an isotropic refractive index. We exploit conformal-mapping to transfer the full Maxwell fisheye into a finite circle. Unlike our previous design that requires a mirror of Zhukovski airfoil shape, this approach can work without a mirror, while offering a comparable imaging resolution. This medium may also be used as an isotropic gradient index lens to transform a light source inside it into two identical sources of null interference. A merit of this approach is reduction of the near-zero-index area from an infinite zone into a finite one, which shall ease its realization.
The infinite sites model of genome evolution
Ma, Jian; Ratan, Aakrosh; Raney, Brian J.; Suh, Bernard B.; Miller, Webb; Haussler, David
2008-01-01
We formalize the problem of recovering the evolutionary history of a set of genomes that are related to an unseen common ancestor genome by operations of speciation, deletion, insertion, duplication, and rearrangement of segments of bases. The problem is examined in the limit as the number of bases in each genome goes to infinity. In this limit, the chromosomes are represented by continuous circles or line segments. For such an infinite-sites model, we present a polynomial-time algorithm to find the most parsimonious evolutionary history of any set of related present-day genomes. PMID:18787111
Effects of dilution on vehicle emissions of primary particles
NASA Astrophysics Data System (ADS)
Hayden, K. L.; Li, S.; Liggio, G.; McCurdy, M.; Chan, T.; Rostkowski, J.
2009-12-01
Dilution of primary aerosols from vehicles into the ambient atmosphere can change their physical and chemical characteristics. In order to study these processes, experiments were conducted in an engine testing facility at Environment Canada in Ottawa, Ontario. Exhaust from a light duty diesel engine was vented into a constant volume sampling (CVS) system where it underwent primary dilution at an ambient temperature of 25oC, leading to a primary dilution ratio of 10-15. From the CVS, the exhaust was further diluted using a combination of a Dekati ejection diluter and mixing with zero air in a flow tube, achieving secondary dilution ratios of up to 3000. Particle and gas measurements were made through multi-ports in the CVS and the flow tube using an SMPS, FMPS, AMS, and SP2, and instruments to measure CO, CO2, NOx, and total hydrocarbons (THC). Preliminary results indicate that regardless of dilution ratios, primary particles contain significant amounts of organic material that appear to reside on small black carbon cores. With increasing dilution ratios, the primary particle sizes become progressively smaller, suggesting volatilization of the adsorbed organic material. Results from various engine operating modes (simulating different driving conditions) will be presented.
Dilution refrigeration for space applications
NASA Technical Reports Server (NTRS)
Israelsson, U. E.; Petrac, D.
1990-01-01
Dilution refrigerators are presently used routinely in ground based applications where temperatures below 0.3 K are required. The operation of a conventional dilution refrigerator depends critically on the presence of gravity. To operate a dilution refrigerator in space many technical difficulties must be overcome. Some of the anticipated difficulties are identified in this paper and possible solutions are described. A single cycle refrigerator is described conceptually that uses forces other than gravity to function and the stringent constraints imposed on the design by requiring the refrigerator to function on the earth without using gravity are elaborated upon.
Infinite densities for Lévy walks.
Rebenshtok, A; Denisov, S; Hänggi, P; Barkai, E
2014-12-01
Motion of particles in many systems exhibits a mixture between periods of random diffusive-like events and ballistic-like motion. In many cases, such systems exhibit strong anomalous diffusion, where low-order moments 〈|x(t)|(q)〉 with q below a critical value q(c) exhibit diffusive scaling while for q>q(c) a ballistic scaling emerges. The mixed dynamics constitutes a theoretical challenge since it does not fall into a unique category of motion, e.g., the known diffusion equations and central limit theorems fail to describe both aspects. In this paper we resolve this problem by resorting to the concept of infinite density. Using the widely applicable Lévy walk model, we find a general expression for the corresponding non-normalized density which is fully determined by the particles velocity distribution, the anomalous diffusion exponent α, and the diffusion coefficient K(α). We explain how infinite densities play a central role in the description of dynamics of a large class of physical processes and discuss how they can be evaluated from experimental or numerical data. PMID:25615072
DeLacy, Brendan G; Bandy, Alan R
2008-01-01
An atmospheric pressure ionization mass spectrometry/isotopically labeled standard (APIMS/ILS) method has been developed for the determination of carbon dioxide (CO(2)) concentration. Descriptions of the instrumental components, the ionization chemistry, and the statistics associated with the analytical method are provided. This method represents an alternative to the nondispersive infrared (NDIR) technique, which is currently used in the atmospheric community to determine atmospheric CO(2) concentrations. The APIMS/ILS and NDIR methods exhibit a decreased sensitivity for CO(2) in the presence of water vapor. Therefore, dryers such as a nafion dryer are used to remove water before detection. The APIMS/ILS method measures mixing ratios and demonstrates linearity and range in the presence or absence of a dryer. The NDIR technique, on the other hand, measures molar concentrations. The second half of this paper describes errors in molar concentration measurements that are caused by drying. An equation describing the errors was derived from the ideal gas law, the conservation of mass, and Dalton's Law. The purpose of this derivation was to quantify errors in the NDIR technique that are caused by drying. Laboratory experiments were conducted to verify the errors created solely by the dryer in CO(2) concentration measurements post-dryer. The laboratory experiments verified the theoretically predicted errors in the derived equations. There are numerous references in the literature that describe the use of a dryer in conjunction with the NDIR technique. However, these references do not address the errors that are caused by drying.
DeLacy, Brendan G; Bandy, Alan R
2008-01-01
An atmospheric pressure ionization mass spectrometry/isotopically labeled standard (APIMS/ILS) method has been developed for the determination of carbon dioxide (CO(2)) concentration. Descriptions of the instrumental components, the ionization chemistry, and the statistics associated with the analytical method are provided. This method represents an alternative to the nondispersive infrared (NDIR) technique, which is currently used in the atmospheric community to determine atmospheric CO(2) concentrations. The APIMS/ILS and NDIR methods exhibit a decreased sensitivity for CO(2) in the presence of water vapor. Therefore, dryers such as a nafion dryer are used to remove water before detection. The APIMS/ILS method measures mixing ratios and demonstrates linearity and range in the presence or absence of a dryer. The NDIR technique, on the other hand, measures molar concentrations. The second half of this paper describes errors in molar concentration measurements that are caused by drying. An equation describing the errors was derived from the ideal gas law, the conservation of mass, and Dalton's Law. The purpose of this derivation was to quantify errors in the NDIR technique that are caused by drying. Laboratory experiments were conducted to verify the errors created solely by the dryer in CO(2) concentration measurements post-dryer. The laboratory experiments verified the theoretically predicted errors in the derived equations. There are numerous references in the literature that describe the use of a dryer in conjunction with the NDIR technique. However, these references do not address the errors that are caused by drying. PMID:18574165
Intermittency in dilute granular flows
NASA Astrophysics Data System (ADS)
Guo, Wenxuan; Zhang, Qiang; Wylie, Jonathan J.
2016-07-01
In this letter, we show that dilute granular systems can exhibit a type of intermittency that has no analogue in gas dynamics. We consider a simple system in which a very dilute set of granular particles falls under gravity through a nozzle. This setting is analogous to the classical problem of high-speed nozzle flow in the study of compressible gases. It is well known that very dilute granular systems exhibit behavior qualitatively similar to gases, and that gas flowing through a nozzle does not exhibit intermittency. Nevertheless, we show that the intermittency in dilute granular nozzle flows can occur and corresponds to complicated transitions between supersonic and subsonic regimes. We also provide detailed explanations of the mechanism underlying this phenomenon.
Cluster approach to dilute magnetism
NASA Astrophysics Data System (ADS)
Holvorcem, Paulo R. C.; Osório, Roberto
1988-10-01
A cluster algebra is developed for the definition of independent correlation functions in the cluster-variation method (CVM) for the spin-1 Ising model. A scheme is then introduced for the study of site-dilute spin- {1}/{2} Ising models by means of the CVM. The procedure regards the site-dilute spin- {1}/{2} model as the spin-1 model with additional constraints due to dilution. The Desjardins-Steinsvoll algortihm is used for the transformation of the CVM equations into a set of differential equations for the independent correlation functions with the inverse temperature as parameter. The evolution of the correlation functions with temperature and the behavior of response functions such as the specific heat and the susceptability are then obtained for any degree of dilution. As an introduction to this scheme, its detailed application is presented here for the simple case of the pair approximation.
Dilution jet mixing program, supplementary report
NASA Technical Reports Server (NTRS)
Srinivasan, R.; White, C.
1986-01-01
The velocity and temperature distributions predicted by a 3-D numerical model and experimental measurements are compared. Empirical correlations for the jet velocity trajectory developed are presented. The measured velocity distributions for all test cases of phase through phase 3 are presented in the form of contour and oblique plots. quantification of the effects of the following on the jet mixing characteristics with a confined crossflow are: (1) orifice geometry momentum flux ratio and density ratio; (2) nonuniform mainstream temperature and velocity profiles upstream of dilution orifices; (3) cold versus hot jet injection; (4) cross-stream flow are a convergence as encountered in practical dilution zone geometries; (5) 2-D slot versus circular orifices; (6) discrete noncirculcer orifices; (7) single-sided versus opposed jets; (8) single row of jets.
40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.
Code of Federal Regulations, 2010 CFR
2010-07-01
... dilution system, you may use a laminar flow element, an ultrasonic flow meter, a subsonic venturi, a... § 1065.240 Dilution air and diluted exhaust flow meters. (a) Application. Use a diluted exhaust flow meter to determine instantaneous diluted exhaust flow rates or total diluted exhaust flow over a...
An Infinite Mixture Model for Coreference Resolution in Clinical Notes
Liu, Sijia; Liu, Hongfang; Chaudhary, Vipin; Li, Dingcheng
2016-01-01
It is widely acknowledged that natural language processing is indispensable to process electronic health records (EHRs). However, poor performance in relation detection tasks, such as coreference (linguistic expressions pertaining to the same entity/event) may affect the quality of EHR processing. Hence, there is a critical need to advance the research for relation detection from EHRs. Most of the clinical coreference resolution systems are based on either supervised machine learning or rule-based methods. The need for manually annotated corpus hampers the use of such system in large scale. In this paper, we present an infinite mixture model method using definite sampling to resolve coreferent relations among mentions in clinical notes. A similarity measure function is proposed to determine the coreferent relations. Our system achieved a 0.847 F-measure for i2b2 2011 coreference corpus. This promising results and the unsupervised nature make it possible to apply the system in big-data clinical setting.
Susantitaphong, Paweena; Tiranathanagul, Khajohn; Katavetin, Pisut; Hanwiwatwong, Orawadee; Wittayalertpanya, Supeecha; Praditpornsilpa, Kearkiat; Tungsanga, Kriang; Eiam-Ong, Somchai
2012-12-01
Mid-dilution and mixed-dilution on-line hemodiafiltration (OL-HDF) techniques are innovated to overcome the limitations of two standard techniques including predilution and postdilution. Unfortunately, the head-to-head comparisons between these two novel techniques in the same study are still limited. Moreover, the original mid-dilution and mixed-dilution OL-HDF need special dialyzers and special machines. In the present study, simple mid-dilution and simple mixed-dilution OL-HDF were settled with the aim for clinical use in general hemodialysis (HD) centers. The efficacies of uremic toxins removal between both modalities were measured and compared. This prospective randomized crossover study was conducted on 12 stable HD patients undergoing simple mixed-dilution and simple mid-dilution OL-HDF techniques. HD prescriptions were similar in both techniques. The dialysis efficacies were determined by calculating small- (urea, creatinine, and phosphate) and middle-molecule (beta-2 microglobulin [β2M]) removal. Moreover, potential complications such as high transmembrane pressure (TMP) and protein loss were also observed. Simple mixed-dilution OL-HDF provided significantly greater clearances of urea, creatinine, and β2M when compared with the simple mid-dilution OL-HDF techniques. Phosphate clearances in both techniques were comparable. In addition, TMP and dialysate albumin loss were not different. There were no intradialytic complications in both techniques. Simple mixed-dilution OL-HDF could provide greater efficacy for small- and middle-molecule clearances and acceptable potential risks, while phosphate removal is comparable.
DAVINCI: Dilute Aperture VIsible Nulling Coronagraphic Imager
NASA Technical Reports Server (NTRS)
Shao, Michael; Levine, B. M.; Vasisht, G.; Lane, B. F.; Woodruff, R.; Vasudevan, G.; Samuele, R.; Lloyd, C. A.; Clampin, M.; Lyon, R.; Guyon, O.
2008-01-01
This slide presentation gives an overview of DAVINCI (Dilute Aperture VIsible Nulling Coronagraphic Imager). The presentation also includes information about dilute aperture coronagraph, and lyot efficiency.
Kroll, Jesse H; Cross, Eben S; Hunter, James F; Pai, Sidhant; Wallace, Lisa M M; Croteau, Philip L; Jayne, John T; Worsnop, Douglas R; Heald, Colette L; Murphy, Jennifer G; Frankel, Sheila L
2015-04-01
The high atmospheric concentrations of toxic gases, particulate matter, and acids in the areas immediately surrounding volcanoes can have negative impacts on human and ecological health. To better understand the atmospheric fate of volcanogenic emissions in the near field (in the first few hours after emission), we have carried out real-time measurements of key chemical components of the volcanic plume from Kı̅lauea on the Island of Hawai'i. Measurements were made at two locations, one ∼ 3 km north-northeast of the vent and the other 31 km to the southwest, with sampling at each site spanning a range of meteorological conditions and volcanic influence. Instrumentation included a sulfur dioxide monitor and an Aerosol Chemical Speciation Monitor, allowing for a measurement of the partitioning between the two major sulfur species (gas-phase SO2 and particulate sulfate) every 5 min. During trade wind conditions, which sent the plume toward the southwest site, sulfur partitioning exhibited a clear diurnal pattern, indicating photochemical oxidation of SO2 to sulfate; this enabled the quantitative determination of plume age (5 h) and instantaneous SO2 oxidation rate (2.4 × 10(-6) s(-1) at solar noon). Under stagnant conditions near the crater, the extent of SO2 oxidation was substantially higher, suggesting faster oxidation. The particles within the plume were extremely acidic, with pH values (controlled largely by ambient relative humidity) as low as -0.8 and strong acidity (controlled largely by absolute sulfate levels) up to 2200 nmol/m(3). The high variability of sulfur partitioning and particle composition underscores the chemically dynamic nature of volcanic plumes, which may have important implications for human and ecological health. PMID:25734883
Statistical Mechanics of Infinite Gravitating Systems
NASA Astrophysics Data System (ADS)
Saslaw, William C.
2008-01-01
The cosmological many-body problem was stated over 300 years ago, but its solution is quite recent and still incomplete. Imagine an infinite expanding universe essentially containing a very large number of objects moving in response to their mutual gravitational forces. What will be the spatial and velocity distributions of these objects and how will they evolve? This question fascinates on many levels. Though inherently non-linear, it turns out to be one of the few analytically solvable problems of statistical mechanics with long range forces. The partition function can be calculated. From this all the thermodynamic properties of the system can be obtained for the grand canonical ensemble. They confirm results derived independently directly from the first and second laws of thermodynamics. The behavior of infinite gravitating systems is quite different from their finite relations such as star clusters. Infinite gravitating systems have regimes of negative specific heat, an unusual type of phase transition, and a very close relation to the observed large-scale structure of our universe. This last feature provides an additional astronomical motivation, especially since the statistical mechanics may be generalized to include effects of dark matter haloes around galaxies. Previously the cosmological many-body problem has mostly been studied using the BBGKY hierarchy (not so suitable in the non-linear regime) and by direct computer integrations of the objects' orbits. The statistical mechanics agrees with and substantially extends these earlier results. Most astrophysicists had previously thought that a statistical thermodynamic approach would not be applicable because: a) many-body gravitational systems have no rigorous equilibrium state, b) the unshielded nature of the long-range force would cause the partition function to diverge on large scales, and c) point masses would produce divergences on small scales. However, deeper considerations show that these are not
Mitchell, J C; Stone, B G; Duane, W C
1992-01-01
Bile acid synthesis can be measured as release of 14CO2 from [26-14C]cholesterol divided by cholesterol specific activity, but this method has not been validated in human subjects. We made twelve comparisons of this CO2 method to standard isotope dilution in six normal subjects and found a mean discrepancy of 6%. Linear regression analysis of one value with respect to the other revealed a correlation coefficient of 0.83 (P less than 0.01), a Y-intercept close to zero (-4.98) and a slope close to 1 (1.06), suggesting good correspondence between the two methods. To assess the potential for error arising from use of serum cholesterol to estimate specific activity of cholesterol used for bile acid synthesis, we compared synthesis measured using serum free cholesterol specific activity to that measured using bile cholesterol specific activity, which is known to be near isotopic equilibrium with the precursor pool used for bile acid synthesis. Synthesis calculated in these two ways differed by less than 10%. The data indicate that the CO2 method using either serum or bile cholesterol specific activity provides a valid estimate of bile acid synthesis in man.
Simulating infinite vortex lattices in superfluids
NASA Astrophysics Data System (ADS)
Mingarelli, Luca; Keaveny, Eric E.; Barnett, Ryan
2016-07-01
We present an efficient framework to numerically treat infinite periodic vortex lattices in rotating superfluids described by the Gross-Pitaevskii theory. The commonly used split-step Fourier (SSF) spectral methods are inapplicable to such systems as the standard Fourier transform does not respect the boundary conditions mandated by the magnetic translation group. We present a generalisation of the SSF method which incorporates the correct boundary conditions by employing the so-called magnetic Fourier transform. We test the method and show that it reduces to known results in the lowest-Landau-level regime. While we focus on rotating scalar superfluids for simplicity, the framework can be naturally extended to treat multicomponent systems and systems under more general ‘synthetic’ gauge fields.
Dynamics for QCD on an Infinite Lattice
NASA Astrophysics Data System (ADS)
Grundling, Hendrik; Rudolph, Gerd
2016-08-01
We prove the existence of the dynamics automorphism group for Hamiltonian QCD on an infinite lattice in R^3, and this is done in a C*-algebraic context. The existence of ground states is also obtained. Starting with the finite lattice model for Hamiltonian QCD developed by Kijowski, Rudolph (cf. J Math Phys 43:1796-1808 [15], J Math Phys 46:032303 [16]), we state its field algebra and a natural representation. We then generalize this representation to the infinite lattice, and construct a Hilbert space which has represented on it all the local algebras (i.e., kinematics algebras associated with finite connected sublattices) equipped with the correct graded commutation relations. On a suitably large C*-algebra acting on this Hilbert space, and containing all the local algebras, we prove that there is a one parameter automorphism group, which is the pointwise norm limit of the local time evolutions along a sequence of finite sublattices, increasing to the full lattice. This is our global time evolution. We then take as our field algebra the C*-algebra generated by all the orbits of the local algebras w.r.t. the global time evolution. Thus the time evolution creates the field algebra. The time evolution is strongly continuous on this choice of field algebra, though not on the original larger C*-algebra. We define the gauge transformations, explain how to enforce the Gauss law constraint, show that the dynamics automorphism group descends to the algebra of physical observables and prove that gauge invariant ground states exist.
Algebraic independence properties related to certain infinite products
NASA Astrophysics Data System (ADS)
Tanaka, Taka-aki
2011-09-01
In this paper we establish algebraic independence of the values of a certain infinite product as well as its all successive derivatives at algebraic points other than its zeroes, using the fact that the logarithmic derivative of an infinite product gives a partial fraction expansion. Such an infinite product is generated by a linear recurrence. The method used for proving the algebraic independence is based on the theory of Mahler functions of several variables.
NASA Astrophysics Data System (ADS)
Garcin, C.; Imbert, P.; Bonville, P.; Hodges, J. A.
1994-12-01
Mössbauer emission measurements on quasi-isolated ^{57}Fe impurities substituted for Cu in La{2-x}SrxCuO4 show a rapid change in the local magnetic behaviour when the Sr content x exceeds an effective value x_t, which is roughly at the centre of the superconducting x range in the phase diagram For x < x_t, the Fe^{3+} impurity systematically pins a Cu spinglass cluster where the spins are oriented near the basal plane, with a freezing temperature of 8 ± 1 K with respect to the characteristic time scale of the Mössbauer probe. For x > x_t, the probe no longer detects local antiferromagnetic ordering, but it reveals the presence of an induced locahzed magnetization in the Cu sublattice, which is preferentially oriented near the {bar c} axis for the largest x values. The results are discussed and compared with other available measurements, including our previous ^{57}Fe Mössbauer absorption study in the saine sertes. Des expériences d'émission Mössbauer effectuées sur des impuretés quasi-isolées de ^{57}Fe substituées à Cu dans La{2-x}Sr{x}CuO4 montrent un changement rapide du comportement magnétique local quand la teneur x en Sr excède une valeur effective x_t, située approximativement au centre du domaine en x associé à la supraconductivité dans le diagramme de phase. Pour x < x_t, l'impureté de Fe^{3+} s'entoure systématiquement d'une zone verre de spin, où les spins du cuivre s'orientent au voisinage du plan de base, avec une température de gel de 8 ± 1 K vis-à-vis du temps de réponse caractéristique de la sonde Mössbauer. Pour x > x_t, la sonde ne détecte plus d'ordre antiferromagnétique local, mais elle révèle l'existence d'une aimantation locale induite dans le sous-réseau du cuivre, qui présente une orientation préférentielle suivant l'axe {bar c} pour les valeurs de x les plus grandes. Les résultats sont discutés et comparés aux autres mesures disponibles, y compris celles de notre étude précédente par absorption M
Bicosomes: Bicelles in Dilute Systems
Rodríguez, Gelen; Soria, Guadalupe; Coll, Elisenda; Rubio, Laia; Barbosa-Barros, Lucyanna; López-Iglesias, Carmen; Planas, Anna M.; Estelrich, Joan; de la Maza, Alfons; López, Olga
2010-01-01
Abstract Bicelles are discoidal phospholipid nanostructures at high lipid concentrations. Under dilute conditions, bicelles become larger and adopt a variety of morphologies. This work proposes a strategy to preserve the discoidal morphology of bicelles in environments with high water content. Bicelles were formed in concentrated conditions and subsequently encapsulated in liposomes. Later dilution of these new structures, called bicosomes, demonstrated that lipid vesicles were able to isolate and protect bicelles entrapped inside them from the medium. Characterization of systems before and after dilution by dynamic light-scattering spectroscopy and cryo-transmission electron microscopy showed that free bicelles changed in size and morphology, whereas encapsulated bicelles remained unaltered by the effect of dilution. Free and entrapped bicelles (containing the paramagnetic contrast agent gadodiamide) were injected into rat brain lateral ventricles. Coronal and sagittal visualization was performed by magnetic resonance imaging. Whereas rats injected with free bicelles did not survive the surgery, those injected with bicosomes did, and a hyperintensity effect due to gadodiamide was observed in the cerebrospinal fluid. These results indicate that bicosomes are a good means of preserving the morphology of bicelles under dilution conditions. PMID:20643066
Solubility of drugs in aqueous solutions. Part 4. Drug solubility by the dilute approximation.
Ruckenstein, E; Shulgin, I
2004-07-01
As in our previous publications in this journal [Int. J. Pharm. 258 (2003a) 193; Int. J. Pharm. 260 (2003b) 283; Int. J. Pharm. 267 (2003c) 121], this paper is concerned with the solubility of poorly soluble drugs in aqueous mixed solvents. In the previous publications, the solubilities of drugs were assumed to be low enough for the so-called infinite dilution approximation to be applicable. In contrast, in the present paper, the solubilities are considered to be finite and the dilute solution approximation is employed. As before, the fluctuation theory of solutions is used to express the derivatives of the activity coefficient of a solute in a ternary solution (dilute solute concentrations in a binary solvent) with respect to the concentrations of the solvent and cosolvent. The expressions obtained are combined with a theoretical equation for the activity coefficient of the solute. As a result, the activity coefficient of the solute was expressed through the activity coefficients of the solute at infinite dilution, solute mole fraction, some properties of the binary solvent (composition, molar volume and activity coefficients of the components) and parameters reflecting the nonidealities of binary species. The expression thus obtained was used to derive an equation for the solubility of poorly soluble drugs in aqueous binary solvents which was applied in two different ways. First, the nonideality parameters were considered as adjustable parameters, determined from experimental solubility data. Second, the obtained equation was used to correct the solubilities of drugs calculated via the infinite dilution approximation. It was shown that both procedures provide accurate correlations for the drug solubility.
Pang, Yu; Liu, Yu-Shan; Liu, Jin-Xi; Feng, Wen-Jie
2016-04-01
In this paper, SH bulk/surface waves propagating in the corresponding infinite/semi-infinite piezoelectric (PE)/piezomagnetic (PM) and PM/PE periodically layered composites are investigated by two methods, the stiffness matrix method and the transfer matrix method. For a semi-infinite PE/PM or PM/PE medium, the free surface is parallel to the layer interface. Both PE and PM materials are assumed to be transversely isotropic solids. Dispersion equations are derived by the stiffness/transfer matrix methods, respectively. The effects of electric-magnetic (ME) boundary conditions at the free surface and the layer thickness ratios on dispersion curves are considered in detail. Numerical examples show that the results calculated by the two methods are the same. The dispersion curves of SH surface waves are below the bulk bands or inside the frequency gaps. The ratio of the layer thickness has an important effect not only on the bulk bands but also on the dispersion curves of SH surface waves. Electric and magnetic boundary conditions, respectively, determine the dispersion curves of SH surface waves for the PE/PM and PM/PE semi-infinite structures. The band structures of SH bulk waves are consistent for the PE/PM and PM/PE structures, however, the dispersive behaviors of SH surface waves are indeed different for the two composites. The realization of the above-mentioned characteristics of SH waves will make it possible to design PE/PM acoustic wave devices with periodical structures and achieve the better performance.
Pang, Yu; Liu, Yu-Shan; Liu, Jin-Xi; Feng, Wen-Jie
2016-04-01
In this paper, SH bulk/surface waves propagating in the corresponding infinite/semi-infinite piezoelectric (PE)/piezomagnetic (PM) and PM/PE periodically layered composites are investigated by two methods, the stiffness matrix method and the transfer matrix method. For a semi-infinite PE/PM or PM/PE medium, the free surface is parallel to the layer interface. Both PE and PM materials are assumed to be transversely isotropic solids. Dispersion equations are derived by the stiffness/transfer matrix methods, respectively. The effects of electric-magnetic (ME) boundary conditions at the free surface and the layer thickness ratios on dispersion curves are considered in detail. Numerical examples show that the results calculated by the two methods are the same. The dispersion curves of SH surface waves are below the bulk bands or inside the frequency gaps. The ratio of the layer thickness has an important effect not only on the bulk bands but also on the dispersion curves of SH surface waves. Electric and magnetic boundary conditions, respectively, determine the dispersion curves of SH surface waves for the PE/PM and PM/PE semi-infinite structures. The band structures of SH bulk waves are consistent for the PE/PM and PM/PE structures, however, the dispersive behaviors of SH surface waves are indeed different for the two composites. The realization of the above-mentioned characteristics of SH waves will make it possible to design PE/PM acoustic wave devices with periodical structures and achieve the better performance. PMID:26836289
Precision of a field method for determination of pH in dilute lakes
Turk, J.T.
1986-01-01
Replicate pH measurements in three dilute lakes made during extreme conditions indicate that pH can be measured in the field with a variance due to measurement error of 0.005 unit. Error of the field technique in measuring the pH of dilute solutions in the laboratory ranges from less than 0.01 unit in dilute strong-acid solutions to about 0.05 unit in air-saturated deionized water.
Stone, P.J.; Bryan-Rhadfi, J.; Lucey, E.C.; Ciccolella, D.E.; Crombie, G.; Faris, B.; Snider, G.L.; Franzblau, C. )
1991-08-01
The accuracy of methods employed to measure the elastin-specific crosslinks, desmosine (DES) and isodesmosine (IDES), has been called into question because contaminants in the urine may cause elevated values. In the present study urine samples were spiked with a known amount of (14C)DES and refluxed in 6 N HCl. Sephadex G-15 chromatography of the hydrolyzed urine employed to remove contaminants. DES and IDES were quantified by high performance liquid chromatography (HPLC) as well as by amino acid analysis. The amount of isotope recovered was used to determine losses during the overall procedure and the isotope dilution to calculate the amounts of endogenous DES and IDES originally present in the urine. Because similar values were obtained by both methods, the more rapid HPLC method was used for all succeeding analyses. In one experiment, the DES amounts in urine collected from hamsters for 3 days after intratracheal treatment with human neutrophil elastase (300 micrograms) or porcine pancreatic elastase (300 micrograms) were 0.212 {plus minus} 0.012 (mean {plus minus} SEM, two measurements on a single pool) and 0.816 {plus minus} 0.005 (two measurements) microgram per hamster per day, respectively. Urine from control hamsters had a mean value of 0.074 {plus minus} 0.008 (eight measurements) microgram per hamster per day. The HNE- and PPE-treated hamsters had mean linear intercept values of 119 and 159% of control values, respectively, giving a positive correlation between increase in airspace size and elevation of urinary DES.
Infinite statistics condensate as a model of dark matter
Ebadi, Zahra; Mirza, Behrouz; Mohammadzadeh, Hosein E-mail: b.mirza@cc.iut.ac.ir
2013-11-01
In some models, dark matter is considered as a condensate bosonic system. In this paper, we prove that condensation is also possible for particles that obey infinite statistics and derive the critical condensation temperature. We argue that a condensed state of a gas of very weakly interacting particles obeying infinite statistics could be considered as a consistent model of dark matter.
A New Look at Infinitives in Business and Technical Writing.
ERIC Educational Resources Information Center
Myers, Marshall
2002-01-01
Argues the infinitive phrase has not been taken seriously in writing because writers have been too concerned with Bishop Robert Lowth's proscription against the split infinitive. Notes that examination of three types of technical prose (instructions, annual reports, and "junk mail") reveals that more than one sentence in four contains an…
Equations of gas dynamics admitting an infinite number of symmetries
Meshkov, A.G.; Mikhalyaev, B.B.
1988-02-01
All the equations of state for which the equations of one-dimensional gas dynamics have an infinite Lie-Baecklund algebra are found. In all these cases, the gas-dynamic equations can either be integrated directly or represented in Lax form. A method for constructing an infinite set of conservation laws is indicated.
Hamel's Formalism for Infinite-Dimensional Mechanical Systems
NASA Astrophysics Data System (ADS)
Shi, Donghua; Berchenko-Kogan, Yakov; Zenkov, Dmitry V.; Bloch, Anthony M.
2016-09-01
In this paper, we introduce Hamel's formalism for infinite-dimensional mechanical systems and in particular consider its applications to the dynamics of nonholonomically constrained systems. This development is a nontrivial extension of its finite-dimensional counterpart. The analysis is applied to several continuum mechanical systems of interest, including coupled systems and systems with infinitely many constraints.
Solenoid magnetic fields calculated from superposed semi-infinite solenoids
NASA Technical Reports Server (NTRS)
Brown, G. V.; Flax, L.
1966-01-01
Calculation of a thick solenoid coils magnetic field components is made by a superposition of the fields produced by four solenoids of infinite length and zero inner radius. The field produced by this semi-infinite solenoid is dependent on only two variables, the radial and axial field point coordinates.
Hearing and Infinite-Period Bifurcations
NASA Astrophysics Data System (ADS)
Ji, Seung; Bozovic, Dolores; Bruinsma, Robijn
2011-03-01
Auditory and vestibular systems present us with biological sensors that can achieve sub-nanometer sensitivity orders of magnitude in the dynamic range, while operating in a fluid-immersed, room-temperature environment. While the mechanisms behind this extreme sensitivity and robustness of the inner ear have not been fully explained, nonlinear response has been shown to be crucial to its proper function. Recent experiments have recorded innate motility of hair cells of the bullfrog sacculus, under varying degrees of steady-state offset. The bundle deflection was shown to suppress or enhance spontaneous oscillations, and affect the sensitivity of the mechanical response. We will present a theoretical model based on cubic nonlinearity and show that in different parameter regimes, the system can be induced to cross a supercritical Hopf bifurcation, an infinite-period bifurcation, or a multi-critical point. Comparing the numerical simulation to the experiment, we will present evidence that the multi-critical point corresponds most closely to the dynamic state of saccular hair cells. Further, we will discuss the crossing of the bifurcation, and the sensitivity of the phase-locked response in various frequency regimes.
Control system for an infinitely variable transmission
Sakai, Y.
1986-12-09
This patent describes a control system for an infinitely variable belt-drive transmission having a selector device including a drive range position and a neutral position, a drive pulley having a hydraulically shiftable disc and a servo chamber for shifting the disc, and a driven pulley having a hydraulically shiftable disc and a servo chamber for shifting the disc. It also has a belt engaged with both the pulleys, a hydraulic control circuit for supplying oil to the servo chambers and for draining the servo chambers. The hydraulic control circuit is provided with a pressure regulator valve for providing a line pressure and a transmission ratio control valve for applying the line pressure to the servo chamber of the drive pulley. The improvement described here comprises: a lubricating oil circuit provided in the hydraulic control circuit for supplying lubricating oil to the drive and driven pulleys; a passage for supplying a part of the lubricating oil to the servo chamber of the drive pulley; a check valve provided in the passage for preventing the reverse flow of the lubricating oil; and a select position detecting valve for enabling the supply of the lubricating oil to the servo chamber at the selection of the neutral position.
NASA Astrophysics Data System (ADS)
Wang, Xu; Zhou, Kun
2015-04-01
Within the framework of the Kirchhoff-Love isotropic and homogeneous plate theory, we obtain, in a unified manner, the analytic solutions to the Eshelby's problem of an inclusion of arbitrary shape with uniform eigencurvatures in an infinite plate, a semi-infinite plate, one of two bonded semi-infinite plates or a circular plate by means of conformal mapping and analytical continuation. The edge of the semi-infinite plate can be rigidly clamped, free or simply supported, while that of the circular plate can be rigidly clamped, free or perfectly bonded to the surrounding infinite plate. Several examples of practical and theoretical interests are presented to demonstrate the general method. In particular, the elementary expressions of the internal elastic fields of bending moments and deflections within an ( n + 1)-fold rotational symmetric inclusion described by a five-term mapping function, a symmetric airfoil cusp inclusion, a symmetric lip cusp inclusion and an inclusion described by a rational mapping function in an infinite plate are derived.
Modeling of DNA thermophoresis in dilute solutions using the non-equilibrium thermodynamics approach
NASA Astrophysics Data System (ADS)
Eslamian, Morteza; Saghir, M. Ziad
2012-03-01
Our previous approach on thermodiffusion modeling of dilute polymer solutions is extended to dilute DNA solutions. The model is based on linear non-equilibrium thermodynamics and the concept of Eyring's activation energy of viscous flow to estimate the Soret coefficient in thermophoresis of macromolecules that are not in liquid phase. The net heat of transport of single- and double-stranded DNA molecules, which are in solid state, are replaced by the activation energy of viscous flow of liquid alkanes with comparable molecular weights. The proposed formula is tested against available experimental data and qualitative agreement is observed. For double-stranded DNA molecules, the experimental data are scattered and the model can qualitatively predict the data, whereas for single-stranded DNA experiments in the infinite dilution model, for which the model is prescribed, a very good agreement is observed.
Field observations of dilution on the Ipanema Beach outfall.
Roldão, J; Carvalho, J L; Roberts, P J
2001-01-01
Field observations of the Ipanema Beach, Rio de Janeiro, ocean sewage outfall are presented. Measurements of dilution and other wastefield characteristics were obtained by adding dye tracer to the effluent and measuring in-situ. Simultaneous measurements of oceanographic conditions were made by Acoustic Doppler Current Profilers, thermistor strings, and profiling instruments. Four experiments were performed, two during unstratified conditions when the plume was surfacing, and two during conditions of strong stratification when the plume was submerged. The minimum dilution varied from 30 to 130. The measurements reflect the worst case conditions as the campaigns were all made for weak currents. PMID:11443984
Diemer, J; Vogl, J; Quétel, C R; Linsinger, T; Taylor, P D; Lamberty, A; Pauwels, J
2001-07-01
The development and implementation of a method for the certification of cadmium in blood samples at low ng g(-1) and sub ng g(-1) levels is described. The analytical procedure is based on inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) applied as a primary method of measurement. Two different sample digestion methods, an optimized microwave digestion procedure using HNO3 and H2O2 as oxidizing agents and a high-pressure asher digestion procedure, were developed and compared. The very high salt content of the digests and the high molybdenum content, which can cause oxide-based interferences with the Cd isotopes, were reduced by a chromatographic matrix separation step using an anion-exchange resin. All isotope ratio measurements were performed by a quadrupole ICP-MS equipped with an ultrasonic nebulizer with membrane desolvator. This sample introduction set-up was used to increase sensitivity and minimize the formation of oxides (less MoO+ interference with the Cd isotopes). Because of the very low Cd concentrations in the samples and the resulting need to minimize the procedural blank as much as possible, all sample-processing steps were performed in a clean room environment. Detection limits of 0.005 ng g(-1) Cd were achieved using sample weights of 2.7 g. The method described was used to recertify the cadmium content of three different blood reference materials from the Community Bureau of Reference (BCR) of the European Commission (BCR-194, BCR-195, BCR- 196). Cadmium concentrations ranged between approximately 0.2 ng g(-1) and approximately 12 ng g(-1). For these materials, SI-traceable certified values including total uncertainty budgets according to ISO and Eurachem guidelines were established.
Motion of a mirror under infinitely fluctuating quantum vacuum stress
NASA Astrophysics Data System (ADS)
Wang, Qingdi; Unruh, William G.
2014-04-01
The actual value of the quantum vacuum energy density is generally regarded as irrelevant in nongravitational physics. However, this paper presents a nongravitational system where this value does have physical significance. The system is a mirror with an internal degree of freedom that interacts with a scalar field. We find that the force exerted on the mirror by the field vacuum undergoes wild fluctuations with a magnitude proportional to the value of the vacuum energy density, which is mathematically infinite. This infinite fluctuating force gives infinite instantaneous acceleration of the mirror. We show that this infinite fluctuating force and infinite instantaneous acceleration make sense because they will not result in infinite fluctuation of the mirror's position. On the contrary, the mirror's fluctuating motion will be confined in a small region due to two special properties of the quantum vacuum: (1) the vacuum friction that resists the mirror's motion and (2) the strong anticorrelation of vacuum fluctuations that constantly changes the direction of the mirror's infinite instantaneous acceleration and thus cancels the effect of infinities to make the fluctuation of the mirror's position finite.
Parabosons, parafermions, and explicit representations of infinite-dimensional algebras
Stoilova, N. I.; Van der Jeugt, J.
2010-03-15
The goal of this paper is to give an explicit construction of the Fock spaces of the parafermion and the paraboson algebra, for an infinite set of generators. This is equivalent to constructing certain unitary irreducible lowest weight representations of the (infinite rank) Lie algebra so({infinity}) and of the Lie superalgebra osp(1 vertical bar {infinity}). A complete solution to the problem is presented, in which the Fock spaces have basis vectors labeled by certain infinite but stable Gelfand-Zetlin patterns, and the transformation of the basis is given explicitly. Alternatively, the basis vectors can be expressed as semi-standard Young tableaux.
Parabosons, parafermions, and explicit representations of infinite-dimensional algebras
NASA Astrophysics Data System (ADS)
Stoilova, N. I.; van der Jeugt, J.
2010-03-01
The goal of this paper is to give an explicit construction of the Fock spaces of the parafermion and the paraboson algebra, for an infinite set of generators. This is equivalent to constructing certain unitary irreducible lowest weight representations of the (infinite rank) Lie algebra so(∞) and of the Lie superalgebra osp(1|∞). A complete solution to the problem is presented, in which the Fock spaces have basis vectors labeled by certain infinite but stable Gelfand-Zetlin patterns, and the transformation of the basis is given explicitly. Alternatively, the basis vectors can be expressed as semi-standard Young tableaux.
Tight Lower Bound for Percolation Threshold on an Infinite Graph
NASA Astrophysics Data System (ADS)
Hamilton, Kathleen E.; Pryadko, Leonid P.
2014-11-01
We construct a tight lower bound for the site percolation threshold on an infinite graph, which becomes exact for an infinite tree. The bound is given by the inverse of the maximal eigenvalue of the Hashimoto matrix used to count nonbacktracking walks on the original graph. Our bound always exceeds the inverse spectral radius of the graph's adjacency matrix, and it is also generally tighter than the existing bound in terms of the maximum degree. We give a constructive proof for existence of such an eigenvalue in the case of a connected infinite quasitransitive graph, a graph-theoretic analog of a translationally invariant system.
Büttler, Rahel M; Martens, Frans; Kushnir, Mark M; Ackermans, Mariette T; Blankenstein, Marinus A; Heijboer, Annemieke C
2015-01-01
The adrenal and gonadal androgens, testosterone, androstenedione and dehydroepiandrosterone (DHEA) play an important role in sexual development as well as in other processes. We developed a method for simultaneous quantitative analysis of serum and plasma testosterone, androstenedione and DHEA levels using Isotope-Dilution Liquid-Chromatography Tandem Mass Spectrometry (ID-LC-MS/MS). Samples underwent liquid-liquid extraction and were analyzed on an Acquity 2D-UPLC-System and a Xevo TQ-S tandem mass spectrometer (Waters). The intra-assay and inter-assay coefficients of variation were <4.0%, <6.3% and <7.0% and <6.0%, <8.1% and <7.7% for testosterone, androstenedione and DHEA, respectively. Inter-assay CVs at the lower limit were 10.6%, 16.9% and 9.0% for testosterone (0.10nmol/L), androstenedione (0.10nmol/L) and DHEA (1.0nmol/L), respectively. Recoveries of spiked analytes were 93-107%. The present testosterone method compared well (y=1.00x-0.04; r=0.998) to a published ID-LC-MS/MS method for testosterone in our lab. The latter method being concordant with a published reference method (Bui et al., 2013). The present method compared well to a published ID-LC-MS/MS method (Kushnir et al., 2010) (y=1.06x-0.06; r=0.996 for testosterone; y=1.04x-0.04; r=0.995 for androstenedione and y=1.03x+0.01; r=0.991 for DHEA). In conclusion, we developed a sensitive and accurate ID-LC-MS/MS method to simultaneously measure serum testosterone, androstenedione and DHEA in serum and plasma.
An Infinite Mixture Model for Coreference Resolution in Clinical Notes
Liu, Sijia; Liu, Hongfang; Chaudhary, Vipin; Li, Dingcheng
2016-01-01
It is widely acknowledged that natural language processing is indispensable to process electronic health records (EHRs). However, poor performance in relation detection tasks, such as coreference (linguistic expressions pertaining to the same entity/event) may affect the quality of EHR processing. Hence, there is a critical need to advance the research for relation detection from EHRs. Most of the clinical coreference resolution systems are based on either supervised machine learning or rule-based methods. The need for manually annotated corpus hampers the use of such system in large scale. In this paper, we present an infinite mixture model method using definite sampling to resolve coreferent relations among mentions in clinical notes. A similarity measure function is proposed to determine the coreferent relations. Our system achieved a 0.847 F-measure for i2b2 2011 coreference corpus. This promising results and the unsupervised nature make it possible to apply the system in big-data clinical setting. PMID:27595047
An Infinite Mixture Model for Coreference Resolution in Clinical Notes.
Liu, Sijia; Liu, Hongfang; Chaudhary, Vipin; Li, Dingcheng
2016-01-01
It is widely acknowledged that natural language processing is indispensable to process electronic health records (EHRs). However, poor performance in relation detection tasks, such as coreference (linguistic expressions pertaining to the same entity/event) may affect the quality of EHR processing. Hence, there is a critical need to advance the research for relation detection from EHRs. Most of the clinical coreference resolution systems are based on either supervised machine learning or rule-based methods. The need for manually annotated corpus hampers the use of such system in large scale. In this paper, we present an infinite mixture model method using definite sampling to resolve coreferent relations among mentions in clinical notes. A similarity measure function is proposed to determine the coreferent relations. Our system achieved a 0.847 F-measure for i2b2 2011 coreference corpus. This promising results and the unsupervised nature make it possible to apply the system in big-data clinical setting. PMID:27595047
NASA Astrophysics Data System (ADS)
Lazo, E.; Castro, C. E.; Cortés-Cortés, F.
2016-09-01
In this work we study the relationship existing between the localization properties of the diluted and non-diluted direct electrical transmission lines with the overlap amplitude Cijω = 2 | Iiω Ijω | , where Ijω is the amplitude of the electric current function at jth cell of the transmission line for the state with frequency ω. We distribute two values of inductances LA and LB, according to the generalized aperiodic Thue-Morse m-tupling sequence. We find that the behavior of Ci,jω is directly related to the localization properties of the aperiodic sequences measured by the ξ normalized participation number, the Rq Rényi entropies and the μq moments. In addition, we generalize the scaling relationship for the overlap amplitude Ci,jω, i.e., <(Ci,jω) 2 q > =(2/N) 2 q.
Gacs quantum algorithmic entropy in infinite dimensional Hilbert spaces
Benatti, Fabio; Oskouei, Samad Khabbazi Deh Abad, Ahmad Shafiei
2014-08-15
We extend the notion of Gacs quantum algorithmic entropy, originally formulated for finitely many qubits, to infinite dimensional quantum spin chains and investigate the relation of this extension with two quantum dynamical entropies that have been proposed in recent years.
Combating matrix effects in LC/ESI/MS: the extrapolative dilution approach.
Kruve, Anneli; Leito, Ivo; Herodes, Koit
2009-09-28
Liquid chromatography electrospray mass spectrometry--LC/ESI/MS--a primary tool for analysis of low volatility compounds in difficult matrices--suffers from the matrix effects in the ESI ionization. It is well known that matrix effects can be reduced by sample dilution. However, the efficiency of simple sample dilution is often limited, in particular by the limit of detection of the method, and can strongly vary from sample to sample. In this study matrix effect is investigated as the function of dilution. It is demonstrated that in some cases dilution can eliminate matrix effect, but often it is just reduced. Based on these findings we propose a new quantitation method based on consecutive dilutions of the sample and extrapolation of the analyte content to the infinite dilution, i.e. to matrix-free solution. The method was validated for LC/ESI/MS analysis of five pesticides (methomyl, thiabendazole, aldicarb, imazalil, methiocarb) in five matrices (tomato, cucumber, apple, rye and garlic) at two concentration levels (0.5 and 5.0 mg kg(-1)). Agreement between the analyzed and spiked concentrations was found for all samples. It was demonstrated that in terms of accuracy of the obtained results the proposed extrapolative dilution approach works distinctly better than simple sample dilution. The main use of this approach is envisaged for (a) method development/validation to determine the extent of matrix effects and the ways of overcoming them and (b) as a second step of analysis in the case of samples having analyte contents near the maximum residue limits (MRL). PMID:19733738
Optimal feedback control infinite dimensional parabolic evolution systems: Approximation techniques
NASA Technical Reports Server (NTRS)
Banks, H. T.; Wang, C.
1989-01-01
A general approximation framework is discussed for computation of optimal feedback controls in linear quadratic regular problems for nonautonomous parabolic distributed parameter systems. This is done in the context of a theoretical framework using general evolution systems in infinite dimensional Hilbert spaces. Conditions are discussed for preservation under approximation of stabilizability and detectability hypotheses on the infinite dimensional system. The special case of periodic systems is also treated.
Packing Infinite Number of Cubes in a Finite Volume Box
ERIC Educational Resources Information Center
Yao, Haishen; Wajngurt, Clara
2006-01-01
Packing an infinite number of cubes into a box of finite volume is the focus of this article. The results and diagrams suggest two ways of packing these cubes. Specifically suppose an infinite number of cubes; the side length of the first one is 1; the side length of the second one is 1/2 , and the side length of the nth one is 1/n. Let n approach…
A notion of graph likelihood and an infinite monkey theorem
NASA Astrophysics Data System (ADS)
Banerji, Christopher R. S.; Mansour, Toufik; Severini, Simone
2014-01-01
We play with a graph-theoretic analogue of the folklore infinite monkey theorem. We define a notion of graph likelihood as the probability that a given graph is constructed by a monkey in a number of time steps equal to the number of vertices. We present an algorithm to compute this graph invariant and closed formulas for some infinite classes. We have to leave the computational complexity of the likelihood as an open problem.
Characterization of the Dilute Ising Antiferromagnet
Wiener, T.
2000-09-12
A spin glass is a magnetic ground state in which ferromagnetic and antiferromagnetic exchange interactions compete, thereby creating frustration and a multidegenerate state with no long range order. An Ising system is a system where the spins are constrained to lie parallel or antiparallel to a primary axis. There has been much theoretical interest in the past ten years in the effects of applying a magnetic field transverse to the primary axis in an Ising spin glass at low temperatures and thus study phase transitions at the T=0 limit. The focus of this study is to search for and characterize a new Ising spin glass system. This is accomplished by site diluting yttrium for terbium in the crystalline material TbNi{sub 2}Ge{sub 2}. The first part of this work gives a brief overview of the physics of rare earth magnetism and an overview of experimental characteristics of spin glasses. This is followed by the methodology used to manufacture the large single crystals used in this study, as well as the measurement techniques used. Next, a summary of the results of magnetic measurements on across the dilution series from pure terbium to pure yttrium is presented. This is followed by detailed measurements on particular dilutions which demonstrate spin glass behavior. Pure TbNi{sub 2}Ge{sub 2} is an Ising antiferromagnet with a several distinct metamagnetic states below 17 K. As the terbium is alloyed with yttrium, these magnetic states are weakened in a consistent manner, as is seen in measurements of the transition temperatures and analysis of Curie-Weiss behavior at high temperature. At low concentrations of terbium, below 35%, long range order is no longer present and a spin-glass-like state emerges. This state is studied through various measurements, dc and ac susceptibility, resistivity, and specific heat. This magnetic behavior was then compared to that of other well characterized spin glasses. It is concluded that there is a region of concentration s for which a spin
NASA Astrophysics Data System (ADS)
Zifferer, Gerhard; Kornherr, Andreas
2005-05-01
Parameters characteristic of size and shape of single polyethylene chains consisting of 15-60 monomer units dissolved in hexane are calculated by use of molecular-dynamics simulations based on a fully atomistic representation of the system. Results are compared with corresponding calculations in vacuum as well as Monte Carlo simulations of coarse-grained chains. The major concern of the study is a careful check of actual limits and possibilities of atomistic simulations of global properties of polymers. As expected such simulations are still restricted to rather small chain lengths but are already large enough to obey the characteristics of polymer coils.
Hyperuniformity in periodically sheared dilute suspensions
NASA Astrophysics Data System (ADS)
Wilken, Sam; Guerra, Rodrigo; Pine, David J.; Chaikin, Paul M.
Periodically sheared dilute, non-Brownian suspensions explore new configurations through collisions in an otherwise reversible flow. Below a critical strain, the particles remain active until they find a configuration with no collisions and reach an absorbing state. Recent simulations by Hexner and Levine have shown that the configuration of particles in the critically absorbing state is hyperuniform. The particle number fluctuations of hyperuniform systems decrease with counting box size more rapidly than random systems (like the same suspension that is not in a critically absorbing state). We built a compact, lightweight uni-axial shear cell where particle coordinates can be measured while shearing with a confocal microscope. We have identified hyperuniform structures with density fluctuation measurements in colloidal suspensions of up to 40% volume fraction in the critically absorbing state with a strain ramp down protocol and find hyperuniform scaling of the density fluctuations.
Superposition, Transition Probabilities and Primitive Observables in Infinite Quantum Systems
NASA Astrophysics Data System (ADS)
Buchholz, Detlev; Størmer, Erling
2015-10-01
The concepts of superposition and of transition probability, familiar from pure states in quantum physics, are extended to locally normal states on funnels of type I∞ factors. Such funnels are used in the description of infinite systems, appearing for example in quantum field theory or in quantum statistical mechanics; their respective constituents are interpreted as algebras of observables localized in an increasing family of nested spacetime regions. Given a generic reference state (expectation functional) on a funnel, e.g. a ground state or a thermal equilibrium state, it is shown that irrespective of the global type of this state all of its excitations, generated by the adjoint action of elements of the funnel, can coherently be superimposed in a meaningful manner. Moreover, these states are the extreme points of their convex hull and as such are analogues of pure states. As further support of this analogy, transition probabilities are defined, complete families of orthogonal states are exhibited and a one-to-one correspondence between the states and families of minimal projections on a Hilbert space is established. The physical interpretation of these quantities relies on a concept of primitive observables. It extends the familiar framework of observable algebras and avoids some counter intuitive features of that setting. Primitive observables admit a consistent statistical interpretation of corresponding measurements and their impact on states is described by a variant of the von Neumann-Lüders projection postulate.
[Formation of oxalate in oxaliplatin injection diluted with infusion solutions].
Eto, Seiji; Yamamoto, Kie; Shimazu, Kounosuke; Sugiura, Toshimune; Baba, Kaori; Sato, Ayaka; Goromaru, Takeshi; Hagiwara, Yoshiaki; Hara, Keiko; Shinohara, Yoshitake; Takahashi, Kojiro
2014-01-01
Oxaliplatin use can cause acute peripheral neuropathy characterized by sensory paresthesias, which are markedly exacerbated by exposure to cold temperatures, and is a dose-limiting factor in the treatment of colorectal cancer.Oxalate is eliminated in a series of nonenzymatic conversions of oxaliplatin in infusion solutions or biological fluids.Elimination of oxalate from oxaliplatin has been suggested as one of the reasons for the development of acute neuropathy.In this study, we developed a high-performance liquid chromatography(HPLC)-based method to detect oxalate formation, and investigated the time dependent formation of oxalate in oxaliplatin diluted with infusion solutions.The results obtained showed that the amount of oxalate in the solution corresponded to 1.6% of oxaliplatin 8 h after oxaliplatin dilution with a 5% glucose solution. On the other hand, oxalate formation from oxaliplatin diluted with a saline solution was ten-fold higher than that from oxaliplatin diluted with the 5% glucose solution.Most patients who were intravenously injected with oxaliplatin experienced venous pain.As a preventive measure against venous pain, dexamethasone was added to the oxaliplatin injection.We measured the amount of oxalate formed in the dexamethasone-containing oxaliplatin injection diluted with a 5% glucose solution.The amount of oxalate formed when dexamethasone was added did not differ significantly from that formed when dexamethasone was not added.Thus, there are no clinical problems associated with the stability of oxaliplatin solutions.
Dilute Acid and Autohydrolysis Pretreatment
NASA Astrophysics Data System (ADS)
Yang, Bin; Wyman, Charles E.
Exposure of cellulosic biomass to temperatures of about 120-210°C can remove most of the hemicellulose and produce cellulose-rich solids from which high glucose yields are possible with cellulase enzymes. Furthermore, the use of dilute sulfuric acid in this pretreatment operation can increase recovery of hemicellulose sugars substantially to about 85-95% of the maximum possible versus only about 65% if no acid is employed. The use of small-diameter tubes makes it possible to employ high solids concentrations similar to those preferred for commercial operations, with rapid heat-up, good temperature control, and accurate closure of material balances. Mixed reactors can be employed to pretreat larger amounts of biomass than possible in such small-diameter tubes, but solids concentrations are limited to about 15% or less to provide uniform temperatures. Pretreatment of large amounts of biomass at high solids concentrations is best carried out using direct steam injection and rapid pressure release, but closure of material balances in such “steam gun” devices is more difficult. Although flow of water alone or containing dilute acid is not practical commercially, such flow-through configurations provide valuable insight into biomass deconstruction kinetics not possible in the batch tubes, mixed reactors, or steam gun systems.
A Microgravity Helium Dilution Cooler
NASA Technical Reports Server (NTRS)
Roach, Pat R.; Sperans, Joel (Technical Monitor)
1994-01-01
We are developing a He-3-He-4 dilution cooler to operate in microgravity. It uses charcoal adsorption pumps and heaters for its operation; it has no moving parts. It currently operates cyclically to well below 0.1 K and we have designed a version to operate continuously. We expect that the continuous version will be able to provide the long-duration cooling that many experiments need at temperatures down to 0.040 K. More importantly, such a dilution cooler could provide the precooling that enables the use of adiabatic demagnetization techniques that can reach temperatures below 0.001 K. At temperatures below 0.002 K many fascinating microgravity experiments on superfluid He-3 become possible. Among the possibilities are: research into a superfluid He-3 gyroscope, study of the nucleation of the B-phase of superfluid He-3 when the sample is floating out of contact with walls, study of the anisotropy of the surface tension of the B-phase, and NMR experiments on tiny free-floating clusters of superfluid He-3 atoms that should model the shell structure of nuclei.
Neutron Flux Perturbations due to Infinite Plane Absorbers IV: The Exponential Flux Revisited
Williams, M.M.R
2002-02-15
Flux depression factors and measures of asymmetry are presented for an absorbing and scattering slab in an infinite medium in which there is an overall exponential flux. One speed transport theory is employed. The effect of the slab on the exponential flux is determined and the necessary correction factors to recover the unperturbed flux from the activation of the slab are calculated. Although this is an old problem, we present here a new formalism which highlights clearly some important physical aspects.
Representations of Canonical Commutation Relations Describing Infinite Coherent States
NASA Astrophysics Data System (ADS)
Joye, Alain; Merkli, Marco
2016-10-01
We investigate the infinite volume limit of quantized photon fields in multimode coherent states. We show that for states containing a continuum of coherent modes, it is mathematically and physically natural to consider their phases to be random and identically distributed. The infinite volume states give rise to Hilbert space representations of the canonical commutation relations which we construct concretely. In the case of random phases, the representations are random as well and can be expressed with the help of Itô stochastic integrals. We analyze the dynamics of the infinite state alone and the open system dynamics of small systems coupled to it. We show that under the free field dynamics, initial phase distributions are driven to the uniform distribution. We demonstrate that coherences in small quantum systems, interacting with the infinite coherent state, exhibit Gaussian time decay. The decoherence is qualitatively faster than the one caused by infinite thermal states, which is known to be exponentially rapid only. This emphasizes the classical character of coherent states.
Roberts, C.B.; Zhang, J.; Chateauneuf, J.E.; Brennecke, J.F.
1995-06-21
The absolute reactivity of triplet benzophenone ({sup 3}BP) and benzyl free radical (PhCH{sub 2}) toward molecular oxygen (O{sub 2}) in supercritical CO{sub 2} and CHF{sub 3} has been measured by laser flash photolysis (LFP). The transient reactants may be considered to be infinitely dilute solutes reacting with a gaseous cosolvent in a supercritical fluid mixture. Both reactants were found to undergo kinetically controlled reactivity with O{sub 2} and the measured bimolecular rate constants (k{sub hi}) were found to decrease with a decrease in solvent density at reduced pressures between 1.0 and 2.5. These results are consistent with solute reactivity with a `nonattractive` cosolvent. The results are compared with those previously obtained for the reaction of {sup 3}BP with an `attractive` cosolvent, 1,4-cyclohexadiene, in supercritical CO{sub 2} and CHF{sub 3}, in which enhanced {sup 3}BP reactivity was observed due to preferential cosolvent/solute solvation. Integral equation theory has also been applied to model these ternary systems, and the results indicate how the strengths of local solvation forces can influence kinetically controlled reactions in supercritical fluids. 36 refs., 8 figs., 3 tabs.
XAFS in dilute magnetic semiconductors.
Sun, Zhihu; Yan, Wensheng; Yao, Tao; Liu, Qinghua; Xie, Yi; Wei, Shiqiang
2013-10-14
X-Ray absorption fine structure (XAFS) spectroscopy has experienced a rapid development in the last four decades and has proved to be a powerful structure characterization technique in the study of local environments in condensed matter. In this article, we first introduce the XAFS basic principles including theory, data analysis and experiment in some detail. Then we attempt to make a review on the applications of XAFS to the study of atomic and electronic structure in dilute magnetic semiconductor (DMS) systems. The power of XAFS in characterizing this interesting material system, such as determining the occupation sites and distribution of the dopants, detecting the presence of metal clusters or secondary phases, as well as identifying the defect types and dopant valence, will be illuminated by selected examples. This review should be of interest both to newcomers in the DMS field and to an interdisciplinary community of researchers working in synthesis, characterization and utilization of DMS materials. PMID:23884341
Desynchronization in diluted neural networks
Zillmer, Ruediger; Livi, Roberto; Politi, Antonio; Torcini, Alessandro
2006-09-15
The dynamical behavior of a weakly diluted fully inhibitory network of pulse-coupled spiking neurons is investigated. Upon increasing the coupling strength, a transition from regular to stochasticlike regime is observed. In the weak-coupling phase, a periodic dynamics is rapidly approached, with all neurons firing with the same rate and mutually phase locked. The strong-coupling phase is characterized by an irregular pattern, even though the maximum Lyapunov exponent is negative. The paradox is solved by drawing an analogy with the phenomenon of 'stable chaos', i.e., by observing that the stochasticlike behavior is 'limited' to an exponentially long (with the system size) transient. Remarkably, the transient dynamics turns out to be stationary.
Band anticrossing in dilute nitrides
Shan, W.; Yu, K.M.; Walukiewicz, W.; Wu, J.; Ager III, J.W.; Haller, E.E.
2003-12-23
Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states. The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The changes in the conduction band structure result in significant increase in electron effective mass and decrease in the electron mobility, and lead to a large enhance of the maximum doping level in GaInNAs doped with group VI donors. In addition, a striking asymmetry in the electrical activation of group IV and group VI donors can be attributed to mutual passivation process through formation of the nearest neighbor group-IV donor nitrogen pairs.
XAFS in dilute magnetic semiconductors.
Sun, Zhihu; Yan, Wensheng; Yao, Tao; Liu, Qinghua; Xie, Yi; Wei, Shiqiang
2013-10-14
X-Ray absorption fine structure (XAFS) spectroscopy has experienced a rapid development in the last four decades and has proved to be a powerful structure characterization technique in the study of local environments in condensed matter. In this article, we first introduce the XAFS basic principles including theory, data analysis and experiment in some detail. Then we attempt to make a review on the applications of XAFS to the study of atomic and electronic structure in dilute magnetic semiconductor (DMS) systems. The power of XAFS in characterizing this interesting material system, such as determining the occupation sites and distribution of the dopants, detecting the presence of metal clusters or secondary phases, as well as identifying the defect types and dopant valence, will be illuminated by selected examples. This review should be of interest both to newcomers in the DMS field and to an interdisciplinary community of researchers working in synthesis, characterization and utilization of DMS materials.
An investigation of the critical liquid-vapor properties of dilute KCl solutions
Potter, R.W.; Babcock, R.S.; Czamanske, G.K.
1976-01-01
The three parameters that define the critical point, temperature, pressure, and volume have been experimentally determined by means of filling studies in a platinum-lined system for five KCl solutions ranging from 0.006 to 0.568 m. The platinum-lined vessels were used to overcome the problems with corrosion experienced by earlier workers. The critical temperature (tc), pressure (Pc), and volume (Vc) were found to fit the equations {Mathematical expression} from infinite dilution to 1.0 m. ?? 1976 Plenum Publishing Corporation.
Nucleation of flocs in dilute colloidal suspensions
Agrawal, D.C.; Raj, R.; Cohen, C. )
1989-11-01
In contrast to earlier theories which assume that coagulation of particles in dilute colloidal suspensions occurs by random collisions, the authors present evidence that coagulation is limited by a nucleation and growth phenomenon, typical of a phase transformation. They show that suspensions of well-dispersed particles, which are almost indefinitely stable, flocculate rapidly when seeded with pregrown flocs. The nucleation argument is supported further by the observation that flocs which are grown at low {zeta} potential, where the particles strongly attract, do not peptize when the pH is changed to high {zeta} potential, where the attraction is weak. The experiments were carried out with aqueous dispersions of alumina particles. The timedependent change in cluster sizes was measured by in situ photon correlation spectroscopy. The observations raise the question of agglomeration as a phase transformation, involving a change in entropy, when the system moves from a dispersed to a flocculated state.
Dilution in single pass arc welds
DuPont, J.N.; Marder, A.R.
1996-06-01
A study was conducted on dilution of single pass arc welds of type 308 stainless steel filler metal deposited onto A36 carbon steel by the plasma arc welding (PAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and submerged arc welding (SAW) processes. Knowledge of the arc and melting efficiency was used in a simple energy balance to develop an expression for dilution as a function of welding variables and thermophysical properties of the filler metal and substrate. Comparison of calculated and experimentally determined dilution values shows the approach provides reasonable predictions of dilution when the melting efficiency can be accurately predicted. The conditions under which such accuracy is obtained are discussed. A diagram is developed from the dilution equation which readily reveals the effect of processing parameters on dilution to aid in parameter optimization.
40 CFR 1065.340 - Diluted exhaust flow (CVS) calibration.
Code of Federal Regulations, 2011 CFR
2011-07-01
... SSV. (7) Incrementally close the restrictor valve or decrease the blower speed to decrease the flow... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Diluted exhaust flow (CVS) calibration... POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Calibrations and Verifications Flow-Related Measurements §...
Dilution mixing estimates of trace metal concentrations of suspended sediments
Marcus, W.A. )
1989-02-01
Dilution mixing equations, at first glance, appear to provide an easy and useful approach for estimating pollutant loads in sediments of unmonitored stream channels. Results from Left Hand Creek, Colorado, however, indicate that only under proper circumstances can dilution mixing models be used to estimate suspended metal concentrations in unmonitored channels with any accuracy. The utility of this technique is severely limited by errors at monitored sites in measuring metal concentrations within sediments and sediment discharge. Specifically, three general constraints must be met before making dilution mixing estimates of unmonitored concentrations: (1) estimated sediment discharges in an unmonitored tributary should be at least 30 percent of that in the main channel below the confluence; (2) there must be a significant difference between the estimated or monitored metal load in the channel below the confluence and the metal loads of the upstream channels; and (3) travel times between the monitoring sites must be incorporated within the calculations.
Gas dilution system results and application to acid rain utilities
Jolley-Souders, K.; Geib, R.; Dunn, C.
1997-12-31
In 1997, the United States EPA will remove restrictions preventing acid rain utilities from using gas dilution systems for calibration or linearity studies for continuous emissions monitoring, Test Method 205 in 40CFR51 requires that a gas dilution system must produce calibration gases whose measured values are within {+-}2% of predicted values. This paper presents the evaluation of the Environics/CalMat 2020 Dilution System for use in calibration studies. Internal studies show that concentrations generated by this unit are within {+-}0.5% of predicted values. Studies are being conducted by several acid rain utilities to evaluate the Environics/CalMat system using single minor component calibration standards. In addition, an internally generated study is being performed to demonstrate the system`s accuracy using a multi-component gas mixture. Data from these tests will be presented in the final version of the paper.
Dilution cycle control for an absorption refrigeration system
Reimann, Robert C.
1984-01-01
A dilution cycle control system for an absorption refrigeration system is disclosed. The control system includes a time delay relay for sensing shutdown of the absorption refrigeration system and for generating a control signal only after expiration of a preselected time period measured from the sensed shutdown of the absorption refrigeration system, during which the absorption refrigeration system is not restarted. A dilution cycle for the absorption refrigeration system is initiated in response to generation of a control signal by the time delay relay. This control system is particularly suitable for use with an absorption refrigeration system which is frequently cycled on and off since the time delay provided by the control system prevents needless dilution of the absorption refrigeration system when the system is turned off for only a short period of time and then is turned back on.
Direct observation of infinite NiO2 planes in LaNiO2 films
NASA Astrophysics Data System (ADS)
Ikeda, Ai; Krockenberger, Yoshiharu; Irie, Hiroshi; Naito, Michio; Yamamoto, Hideki
2016-06-01
Epitaxial thin films of LaNiO2, which is an oxygen-deficient perovskite with “infinite layers” of Ni1+O2, were prepared by a low-temperature reduction of LaNiO3 single-crystal films on NdGaO3 substrates. We report the high-angle annular dark-field and bright-field scanning transmission electron microscopy observations of infinite NiO2 planes of c-axis-oriented LaNiO2 epitaxial thin films with a layer stacking sequence of NiO2/La/NiO2. Resistivity measurements on the films show T 2 dependence between 400 and 150 K and a negative Hall coefficient.
Permittivity and permeability of semi-infinite metamaterial
NASA Astrophysics Data System (ADS)
Porvatkina, O. V.; Tishchenko, A. A.; Strikhanov, M. N.
2016-08-01
In our work we investigate dielectric and magnetic properties of semi-infinite metamaterial consisting of particles of different possible nature: atoms, molecules, nanoparticles, etc. It is important that these particles would have magnetic properties. Polarization of a near-surface layer is known to differ from its bulk value for non-magnetic materials; for magnetic materials, including metamaterials, the situation should be similar, which is the subject of our research. We obtain analogues of the Clausius-Mossotti relation both for permittivity and permeability taking into account the local field effects in the longwave approximation for semi-infinite metamaterial. These relations describe the connection between macroscopic characteristics of the semi-infinite metamaterial (permittivity and permeability) and characteristics of constituent particles (dielectric polarizability and magnetic polarizability), which is a bright example of multi-scale approach - method very popular today in physical and computer simulating.
Dynamics with infinitely many derivatives: the initial value problem
NASA Astrophysics Data System (ADS)
Barnaby, Neil; Kamran, Niky
2008-02-01
Differential equations of infinite order are an increasingly important class of equations in theoretical physics. Such equations are ubiquitous in string field theory and have recently attracted considerable interest also from cosmologists. Though these equations have been studied in the classical mathematical literature, it appears that the physics community is largely unaware of the relevant formalism. Of particular importance is the fate of the initial value problem. Under what circumstances do infinite order differential equations possess a well-defined initial value problem and how many initial data are required? In this paper we study the initial value problem for infinite order differential equations in the mathematical framework of the formal operator calculus, with analytic initial data. This formalism allows us to handle simultaneously a wide array of different nonlocal equations within a single framework and also admits a transparent physical interpretation. We show that differential equations of infinite order do not generically admit infinitely many initial data. Rather, each pole of the propagator contributes two initial data to the final solution. Though it is possible to find differential equations of infinite order which admit well-defined initial value problem with only two initial data, neither the dynamical equations of p-adic string theory nor string field theory seem to belong to this class. However, both theories can be rendered ghost-free by suitable definition of the action of the formal pseudo-differential operator. This prescription restricts the theory to frequencies within some contour in the complex plane and hence may be thought of as a sort of ultra-violet cut-off. Our results place certain recent attempts to study inflation in the context of nonlocal field theories on a much firmer mathematical footing.
An inline QC method for determining serial dilution performance of DMSO-based systems.
Walling, Leslie A
2011-06-01
Serial dilution of compounds solubilized in dimethylsulfoxide (DMSO) for dose-response curves is a common method for efficacy analysis of potential drug candidates. In general, serial dilution methods are particularly prone to error propagation because each dilution is dependent on the previous concentration. Moreover, assumptions about quality control parameters (i.e., dye linearity) can lead to an erroneous process. Here, an inline performance measurement is sought to improve the precision and accuracy of dilution plates. Sulforhodamine 101 (S101) dye is introduced as the quantitative fluorometric method of choice for DMSO-based systems. Although S101 in DMSO behaves in a nonlinear fashion over its detectable range, we account for this with a direct calibration method that includes every point of the dilution template. This report contains dye selection rationale for the S101 dye and its use in quantifying the performance of 96- and 384-well dilution protocols as tested on five identical instruments.
Surface optical Bloch oscillations in semi-infinite waveguide arrays.
Chremmos, I D; Efremidis, N K
2012-06-01
We predict that surface optical Bloch oscillations can exist in semi-infinite waveguide arrays with a linear index variation, if the array parameters close to the boundary are appropriately perturbed. The perturbation is such that the surface states obtain the Wannier-Stark ladder eigenvalues of the unperturbed infinite array. The number of waveguides, whose parameters need to be controlled, decreases with increasing ratio of index gradient over coupling. The configuration can find applications as a "matched" termination of waveguide arrays to eliminate the distortion of Bloch oscillations due to reflection on the boundaries.
Infinite tension limit of the pure spinor superstring
NASA Astrophysics Data System (ADS)
Berkovits, Nathan
2014-03-01
Mason and Skinner recently constructed a chiral infinite tension limit of the Ramond-Neveu-Schwarz superstring which was shown to compute the Cachazo-He-Yuan formulae for tree-level d = 10 Yang-Mills amplitudes and the NS-NS sector of tree-level d = 10 supergravity amplitudes. In this letter, their chiral infinite tension limit is generalized to the pure spinor superstring which computes a d = 10 superspace version of the Cachazo-He-Yuan formulae for tree-level d = 10 super-Yang-Mills and supergravity amplitudes.
Robust Consumption-Investment Problem on Infinite Horizon
Zawisza, Dariusz
2015-12-15
In our paper we consider an infinite horizon consumption-investment problem under a model misspecification in a general stochastic factor model. We formulate the problem as a stochastic game and finally characterize the saddle point and the value function of that game using an ODE of semilinear type, for which we provide a proof of an existence and uniqueness theorem for its solution. Such equation is interested on its own right, since it generalizes many other equations arising in various infinite horizon optimization problems.
Extending NEC to model wire objects in infinite chiral media
Burke, G.J.; Miller, E.K.; Bhattachryya, A.K.
1992-03-01
The development of a moment-method model for wire objects in an infinite chiral medium is described. In this work, the Numerical Electromagnetics Code (NEC) was extended by including a new integral-equation kernel obtained from the dyadic Green`s function for an infinite chiral medium. The NEC moment-method treatment using point matching and a three-term sinusoidal current expansion was adapted to the case of a chiral medium. Examples of current distributions and radiation patterns for simple antennas are presented, and the validation of the code is discussed. 15 refs.
Superlinear nonlocal fractional problems with infinitely many solutions
NASA Astrophysics Data System (ADS)
Binlin, Zhang; Molica Bisci, Giovanni; Servadei, Raffaella
2015-07-01
In this paper we study the existence of infinitely many weak solutions for equations driven by nonlocal integrodifferential operators with homogeneous Dirichlet boundary conditions. A model for these operators is given by the fractional Laplacian where s ∈ (0, 1) is fixed. We consider different superlinear growth assumptions on the nonlinearity, starting from the well-known Ambrosetti-Rabinowitz condition. In this framework we obtain three different results about the existence of infinitely many weak solutions for the problem under consideration, by using the Fountain Theorem. All these theorems extend some classical results for semilinear Laplacian equations to the nonlocal fractional setting.
Gravitational waves from kinks on infinite cosmic strings
Kawasaki, Masahiro; Miyamoto, Koichi; Nakayama, Kazunori
2010-05-15
Gravitational waves emitted by kinks on infinite strings are investigated using detailed estimations of the kink distribution on infinite strings. We find that gravitational waves from kinks can be detected by future pulsar timing experiments such as SKA for an appropriate value of the string tension, if the typical size of string loops is much smaller than the horizon at their formation. Moreover, the gravitational wave spectrum depends on the thermal history of the Universe and hence it can be used as a probe into the early evolution of the Universe.
Commutative law for products of infinitely large isotropic random matrices
NASA Astrophysics Data System (ADS)
Burda, Zdzislaw; Livan, Giacomo; Swiech, Artur
2013-08-01
Ensembles of isotropic random matrices are defined by the invariance of the probability measure under the left (and right) multiplication by an arbitrary unitary matrix. We show that the multiplication of large isotropic random matrices is spectrally commutative and self-averaging in the limit of infinite matrix size N→∞. The notion of spectral commutativity means that the eigenvalue density of a product ABC... of such matrices is independent of the order of matrix multiplication, for example, the matrix ABCD has the same eigenvalue density as ADCB. In turn, the notion of self-averaging means that the product of n independent but identically distributed random matrices, which we symbolically denote by AAA..., has the same eigenvalue density as the corresponding power An of a single matrix drawn from the underlying matrix ensemble. For example, the eigenvalue density of ABCCABC is the same as that of A2B2C3. We also discuss the singular behavior of the eigenvalue and singular value densities of isotropic matrices and their products for small eigenvalues λ→0. We show that the singularities at the origin of the eigenvalue density and of the singular value density are in one-to-one correspondence in the limit N→∞: The eigenvalue density of an isotropic random matrix has a power-law singularity at the origin ˜|λ|-s with a power s∈(0,2) when and only when the density of its singular values has a power-law singularity ˜λ-σ with a power σ=s/(4-s). These results are obtained analytically in the limit N→∞. We supplement these results with numerical simulations for large but finite N and discuss finite-size effects for the most common ensembles of isotropic random matrices.
Dilute Oxygen Combustion - Phase 3 Report
Riley, Michael F.
2000-05-31
Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good, and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel's standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion on furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.
Dilute Oxygen Combustion Phase 3 Final Report
Riley, M.F.; Ryan, H.M.
2000-05-31
Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel?s standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion of furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.
Estimating dilutions for patch testing skin care products: a practical method.
Sherertz, E F; Byers, S V
1997-09-01
When patch testing, it is helpful to patch test with the patient's own topical products. However, the thickness (viscosity) of the product often prevents easy measurement for dilution. A method of estimating volume: volume dilutions that requires minimal investment in supplies is presented. This method is only applicable to personal products and is not suitable for industrial or household chemicals.
40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.
Code of Federal Regulations, 2013 CFR
2013-07-01
... interval. You may use the difference between a diluted exhaust flow meter and a dilution air meter to.... We recommend that you use a diluted exhaust flow meter that meets the specifications in Table 1 of... verification in § 1065.307 and the calibration and verifications in § 1065.340 and § 1065.341. You may use...
40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.
Code of Federal Regulations, 2011 CFR
2011-07-01
... interval. You may use the difference between a diluted exhaust flow meter and a dilution air meter to.... We recommend that you use a diluted exhaust flow meter that meets the specifications in Table 1 of... verification in § 1065.307 and the calibration and verifications in § 1065.340 and § 1065.341. You may use...
40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.
Code of Federal Regulations, 2014 CFR
2014-07-01
... interval. You may use the difference between a diluted exhaust flow meter and a dilution air meter to.... We recommend that you use a diluted exhaust flow meter that meets the specifications in Table 1 of... verification in § 1065.307 and the calibration and verifications in § 1065.340 and § 1065.341. You may use...
40 CFR 1065.240 - Dilution air and diluted exhaust flow meters.
Code of Federal Regulations, 2012 CFR
2012-07-01
... interval. You may use the difference between a diluted exhaust flow meter and a dilution air meter to.... We recommend that you use a diluted exhaust flow meter that meets the specifications in Table 1 of... verification in § 1065.307 and the calibration and verifications in § 1065.340 and § 1065.341. You may use...
Electrocoalescence based serial dilution of microfluidic droplets.
Bhattacharjee, Biddut; Vanapalli, Siva A
2014-07-01
Dilution of microfluidic droplets where the concentration of a reagent is incrementally varied is a key operation in drop-based biological analysis. Here, we present an electrocoalescence based dilution scheme for droplets based on merging between moving and parked drops. We study the effects of fluidic and electrical parameters on the dilution process. Highly consistent coalescence and fine resolution in dilution factor are achieved with an AC signal as low as 10 V even though the electrodes are separated from the fluidic channel by insulator. We find that the amount of material exchange between the droplets per coalescence event is high for low capillary number. We also observe different types of coalescence depending on the flow and electrical parameters and discuss their influence on the rate of dilution. Overall, we find the key parameter governing the rate of dilution is the duration of coalescence between the moving and parked drop. The proposed design is simple incorporating the channel electrodes in the same layer as that of the fluidic channels. Our approach allows on-demand and controlled dilution of droplets and is simple enough to be useful for assays that require serial dilutions. The approach can also be useful for applications where there is a need to replace or wash fluid from stored drops.
Electrocoalescence based serial dilution of microfluidic droplets
Bhattacharjee, Biddut; Vanapalli, Siva A.
2014-01-01
Dilution of microfluidic droplets where the concentration of a reagent is incrementally varied is a key operation in drop-based biological analysis. Here, we present an electrocoalescence based dilution scheme for droplets based on merging between moving and parked drops. We study the effects of fluidic and electrical parameters on the dilution process. Highly consistent coalescence and fine resolution in dilution factor are achieved with an AC signal as low as 10 V even though the electrodes are separated from the fluidic channel by insulator. We find that the amount of material exchange between the droplets per coalescence event is high for low capillary number. We also observe different types of coalescence depending on the flow and electrical parameters and discuss their influence on the rate of dilution. Overall, we find the key parameter governing the rate of dilution is the duration of coalescence between the moving and parked drop. The proposed design is simple incorporating the channel electrodes in the same layer as that of the fluidic channels. Our approach allows on-demand and controlled dilution of droplets and is simple enough to be useful for assays that require serial dilutions. The approach can also be useful for applications where there is a need to replace or wash fluid from stored drops. PMID:25379096
The physics of FEL in an infinite electron beam
Wang, G.; Litvinenko, V.N.; Webb, S.
2010-10-07
We solve linearized Vlasov-Maxwell FEL equations for a 3-D perturbation in the infinite electron beam with Lorentzian energy distributions using paraxial approximation. We present analytical solutions for various initial perturbations and discuss the effect of optical guiding in such system.
Finding Sums for an Infinite Class of Alternating Series
ERIC Educational Resources Information Center
Chen, Zhibo; Wei, Sheng; Xiao, Xuerong
2012-01-01
Calculus II students know that many alternating series are convergent by the Alternating Series Test. However, they know few alternating series (except geometric series and some trivial ones) for which they can find the sum. In this article, we present a method that enables the students to find sums for infinitely many alternating series in the…
Young Students Exploring Cardinality by Constructing Infinite Processes
ERIC Educational Resources Information Center
Kahn, Ken; Sendova, Evgenia; Sacristan, Ana Isabel; Noss, Richard
2011-01-01
In this paper, we describe the design and implementation of computer programming activities aimed at introducing young students (9-13 years old) to the idea of infinity, and in particular, to the cardinality of infinite sets. This research was part of the "WebLabs" project where students from several European countries explored topics in…
How Fragile Is Consolidated Knowledge? Ben's Comparisons of Infinite Sets
ERIC Educational Resources Information Center
Tsamir, Pessia; Dreyfus, Tommy
2005-01-01
This article builds on two previous ones in which we presented the processes of construction and consolidation of one student's knowledge structures about comparisons of infinite sets, according to a recently proposed theory of abstraction. In the present article, we show that under slight variations of context, knowledge structures that have…
Finding sums for an infinite class of alternating series
NASA Astrophysics Data System (ADS)
Chen, Zhibo; Wei, Sheng; Xiao, Xuerong
2012-07-01
Calculus II students know that many alternating series are convergent by the Alternating Series Test. However, they know few alternating series (except geometric series and some trivial ones) for which they can find the sum. In this article, we present a method that enables the students to find sums for infinitely many alternating series in the following form ?
Functional DNA: Teaching Infinite Series through Genetic Analogy
ERIC Educational Resources Information Center
Kowalski, R. Travis
2011-01-01
This article presents an extended analogy that connects infinite sequences and series to the science of genetics, by identifying power series as "DNA for a function." This analogy allows standard topics such as convergence tests or Taylor approximations to be recast in a "forensic" light as mathematical analogs of genetic concepts such as DNA…
Reparametrization of the Relativistic Infinitely Extended Charged Particle Action
NASA Astrophysics Data System (ADS)
Saadat, Hassan; Pourhassan, Behnam
2016-09-01
In this letter, relativistic infinitely extended particles formulated. Correct form of action with possibility of reparametrization obtained and effect of electric field considered. It may be one of the first step to re-introduce theory of every things given by Nakano and Hessaby many years ago.
Plasmonic waves of a semi-infinite random nanocomposite
Moradi, Afshin
2013-10-15
The dispersion curves of the plasmonic waves of a semi-infinite random metal-dielectric nanocomposite, consisting of bulk metal embedded with dielectric inclusions, are presented. Two branches of p-polarized surface plasmon-polariton modes are found to exist. The possibility of experimentally observing the surface waves by attenuated total reflection is demonstrated.
Infinite and Finite Games: Play and Visual Culture
ERIC Educational Resources Information Center
Hicks, Laurie E.
2004-01-01
In this article, I shall argue for the value of conceptualizing, and practicing art education as a kind of play or game, drawing inspiration from the concepts of finite and infinite games articulated by philosopher James Carse (1986). In so doing, I seek to encourage a continuing dialogue with the assumptions that constrain the theoretical basis…
The Limits of Some Infinite Families of Complex Contracting Mappings
Pagon, Dusan
2008-11-13
Self-similarity is strongly presented in modern mathematics and physics. We study a broad class of planar fractals--strongly self-similar sets of points in complex plane, obtained from a unit interval as geometric limits of certain infinite families of contracting mappings. Different 1-1 correspondences between the constructed set and the initial unit interval are established.
On the steady propagation of a semi-infinite crack
Paukshto, M.V.; Sulimov, M.G.
1994-12-25
We consider the rectilinear propagation of a semi-infinite crack with constant velocity in a crystal structure. We obtain the solutions of homogeneous boundary-value problems for the corresponding difference-differential operators in spaces of one and two dimensions. We give a justification of the computational aspect of the problem.
Elasticity and hydrodynamic properties of ``doped solvent dilute'' lamellar phases
NASA Astrophysics Data System (ADS)
Nallet, Frédéric; Roux, Didier; Quilliet, Catherine; Fabre, Pascale; Milner, Scott T.
1994-09-01
The equilibrium fluctuations and weakly out-of-equilibrium relaxation properties of “doped solvent" dilute lamellar phases are investigated, both theoretically and experimentally, in the low-frequency, long-wavelength limit. The physical system of interest is a three-component smectic A lyotropic liquid crystal where surfactant bilayers infinite in extent are periodically stacked along one direction in space and separated by a colloidal solution. Two experimentally relevant modes are found in the lowest frequency part of the fluctuation spectrum of such multicomponent systems. Both are associated to the relaxation of coupled layer displacement and colloid concentration waves. In the limit of small coupling, one mode is close to the well-known undulation/baroclinic mode of two-component lamellar phases, while the other corresponds to the Brownian diffusive motion of the colloid in an anisotropic medium. Elastic constants of the smectic liquid crystal and diffusion parameters of the colloidal solution may be deduced from a measurement of the anisotropic dispersion relation of these two modes, as illustrated by dynamic light scattering experiments on the ferrosmectic system. Les fluctuations à l'équilibre ainsi que la relaxation des états légèrement en dehors de l'équilibre des phases lamellaires à “solvant dopé” sont étudiées, aussi bien d'un point de vue théorique qu'expérimental, dans la limite de basses fréquences et de grandes longueurs d'onde. Les systèmes décrits sont des cristaux-liquides smectiques A lyotropes formés de trois constituants : un tensioactif en solution dans une suspension colloïdale forme des bicouches de grande extension latérale qui s'empilent de façon périodique le long d'une direction dans l'espace. Avec de tels systèmes anisotropes et à plusieurs constituants deux modes présents dans la partie à basse fréquence du spectre des fluctuations (associés à la relaxation d'ondes, couplées, de concentration collo
The Effect of Dilution on Microsegregation in AWS ER NiCrMo-14 Alloy Welding Claddings
NASA Astrophysics Data System (ADS)
Miná, Émerson Mendonça; da Silva, Yuri Cruz; Dille, Jean; Silva, Cleiton Carvalho
2016-10-01
Dilution and microsegregation are phenomena inherent to claddings, which, in turn, directly affect their main properties. This study evaluated microsegregation in the fusion zone with different dilution levels. The overlays were welded by the TIG cold wire feed process. Dilution was calculated from the geometric characteristics of the claddings and from the conservation of mass equation using chemical composition measurements. Microsegregation was calculated using energy dispersive X-ray spectroscopy measurements of the dendrites and the chemical composition of the fusion zone. The dilution of the claddings was increased by reducing the wire feed rate. Fe showed potential to be incorporated into the solid phase (k > 1), and this increased with the increase of dilution. Mo, in turn, was segregated into the liquid phase (k < 1) and also increased with the increase of dilution. However, Cr and W showed a slight decrease in their partition coefficients (k) with the increase of dilution.
Extremely correlated Fermi liquids in the limit of infinite dimensions
Perepelitsky, Edward Sriram Shastry, B.
2013-11-15
We study the infinite spatial dimensionality limit (d→∞) of the recently developed Extremely Correlated Fermi Liquid (ECFL) theory (Shastry 2011, 2013) [17,18] for the t–J model at J=0. We directly analyze the Schwinger equations of motion for the Gutzwiller projected (i.e. U=∞) electron Green’s function G. From simplifications arising in this limit d→∞, we are able to make several exact statements about the theory. The ECFL Green’s function is shown to have a momentum independent Dyson (Mori) self energy. For practical calculations we introduce a partial projection parameter λ, and obtain the complete set of ECFL integral equations to O(λ{sup 2}). In a related publication (Zitko et al. 2013) [23], these equations are compared in detail with the dynamical mean field theory for the large U Hubbard model. Paralleling the well known mapping for the Hubbard model, we find that the infinite dimensional t–J model (with J=0) can be mapped to the infinite-U Anderson impurity model with a self-consistently determined set of parameters. This mapping extends individually to the auxiliary Green’s function g and the caparison factor μ. Additionally, the optical conductivity is shown to be obtainable from G with negligibly small vertex corrections. These results are shown to hold to each order in λ. -- Highlights: •Infinite-dimensional t–J model (J=0) studied within new ECFL theory. •Mapping to the infinite U Anderson model with self consistent hybridization. •Single particle Green’s function determined by two local self energies. •Partial projection through control variable λ. •Expansion carried out to O(λ{sup 2}) explicitly.
Transient Effects in Planar Solidification of Dilute Binary Alloys
NASA Technical Reports Server (NTRS)
Mazuruk, Konstantin; Volz, Martin P.
2008-01-01
The initial transient during planar solidification of dilute binary alloys is studied in the framework of the boundary integral method that leads to the non-linear Volterra integral governing equation. An analytical solution of this equation is obtained for the case of a constant growth rate which constitutes the well-known Tiller's formula for the solute transient. The more physically relevant, constant ramping down temperature case has been studied both numerically and analytically. In particular, an asymptotic analytical solution is obtained for the initial transient behavior. A numerical technique to solve the non-linear Volterra equation is developed and the solution is obtained for a family of the governing parameters. For the rapid solidification condition, growth rate spikes have been observed even for the infinite kinetics model. When recirculating fluid flow is included into the analysis, the spike feature is dramatically diminished. Finally, we have investigated planar solidification with a fluctuating temperature field as a possible mechanism for frequently observed solute trapping bands.
Dilution and volatilization of groundwater contaminant discharges in streams
NASA Astrophysics Data System (ADS)
Aisopou, Angeliki; Bjerg, Poul L.; Sonne, Anne T.; Balbarini, Nicola; Rosenberg, Louise; Binning, Philip J.
2015-01-01
An analytical solution to describe dilution and volatilization of a continuous groundwater contaminant plume into streams is developed for risk assessment. The location of groundwater plume discharge into the stream (discharge through the side versus bottom of the stream) and different distributions of the contaminant plume concentration (Gaussian, homogeneous or heterogeneous distribution) are considered. The model considering the plume discharged through the bank of the river, with a uniform concentration distribution was the most appropriate for risk assessment due to its simplicity and limited data requirements. The dilution and volatilization model is able to predict the entire concentration field, and thus the mixing zone, maximum concentration and fully mixed concentration in the stream. It can also be used to identify groundwater discharge zones from in-stream concentration measurement. The solution was successfully applied to published field data obtained in a large and a small Danish stream and provided valuable information on the risk posed by the groundwater contaminant plumes. The results provided by the dilution and volatilization model are very different to those obtained with existing point source models, with a distributed source leading to a larger mixing length and different concentration field. The dilution model can also provide recommendations for sampling locations and the size of impact zones in streams. This is of interest for regulators, for example when developing guidelines for the implementation of the European Water Framework Directive.
Bathelier, C; Mercier, G; Lucotte, G
1996-12-01
We describe a semiquantitative method to measure hepatitis C virus (HCV) viral particle numbers, by carrying out reverse-transcription polymerase chain reaction (RT-PCR) on serial dilutions of serum samples. The virus concentrations measured were 10(3)-10(6) viral particles ml-1 of serum. The method described is relatively quick, and the only required manipulation is dilution of the serum. An optimal RT-PCR method is used for diluted and undiluted samples.
Predictive Rate-Distortion for Infinite-Order Markov Processes
NASA Astrophysics Data System (ADS)
Marzen, Sarah E.; Crutchfield, James P.
2016-06-01
Predictive rate-distortion analysis suffers from the curse of dimensionality: clustering arbitrarily long pasts to retain information about arbitrarily long futures requires resources that typically grow exponentially with length. The challenge is compounded for infinite-order Markov processes, since conditioning on finite sequences cannot capture all of their past dependencies. Spectral arguments confirm a popular intuition: algorithms that cluster finite-length sequences fail dramatically when the underlying process has long-range temporal correlations and can fail even for processes generated by finite-memory hidden Markov models. We circumvent the curse of dimensionality in rate-distortion analysis of finite- and infinite-order processes by casting predictive rate-distortion objective functions in terms of the forward- and reverse-time causal states of computational mechanics. Examples demonstrate that the resulting algorithms yield substantial improvements.
Accelerated Gibbs Sampling for Infinite Sparse Factor Analysis
Andrzejewski, D M
2011-09-12
The Indian Buffet Process (IBP) gives a probabilistic model of sparse binary matrices with an unbounded number of columns. This construct can be used, for example, to model a fixed numer of observed data points (rows) associated with an unknown number of latent features (columns). Markov Chain Monte Carlo (MCMC) methods are often used for IBP inference, and in this technical note, we provide a detailed review of the derivations of collapsed and accelerated Gibbs samplers for the linear-Gaussian infinite latent feature model. We also discuss and explain update equations for hyperparameter resampling in a 'full Bayesian' treatment and present a novel slice sampler capable of extending the accelerated Gibbs sampler to the case of infinite sparse factor analysis by allowing the use of real-valued latent features.
Polygons in restricted geometries subjected to infinite forces
NASA Astrophysics Data System (ADS)
Beaton, N. R.; Eng, J. W.; Soteros, C. E.
2016-10-01
We consider self-avoiding polygons in a restricted geometry, namely an infinite L × M tube in {{{Z}}}3. These polygons are subjected to a force f, parallel to the infinite axis of the tube. When f\\gt 0 the force stretches the polygons, while when f\\lt 0 the force is compressive. We obtain and prove the asymptotic form of the free energy in both limits f\\to +/- ∞ . We conjecture that the f\\to -∞ asymptote is the same as the limiting free energy of ‘Hamiltonian’ polygons, polygons which visit every vertex in a L× M× N box. We investigate such polygons, and in particular use a transfer-matrix methodology to establish that the conjecture is true for some small tube sizes. Dedicated to Anthony J Guttmann on the occasion of his 70th birthday.
LES investigation of infinite staggered wind-turbine arrays
NASA Astrophysics Data System (ADS)
Yang, Xiaolei; Sotiropoulos, Fotis
2014-12-01
The layouts of turbines affect the turbine wake interactions and thus the wind farm performance. The wake interactions in infinite staggered wind-turbine arrays are investigated and compared with infinite aligned turbine arrays in this paper. From the numerical results we identify three types of wake behaviours, which are significantly different from wakes in aligned wind-turbine arrays. For the first type, each turbine wake interferes with the pair of staggered downstream turbine wakes and the aligned downstream turbine. For the second type, each turbine wake interacts with the first two downstream turbine wakes but does not show significant interference with the second aligned downstream turbine. For the third type, each turbine wake recovers immediately after passing through the gap of the first two downstream turbines and has little interaction with the second downstream turbine wakes The extracted power density and power efficiency are also studied and compared with aligned wind-turbine arrays.
Conformal field theories with infinitely many conservation laws
Todorov, Ivan
2013-02-15
Globally conformal invariant quantum field theories in a D-dimensional space-time (D even) have rational correlation functions and admit an infinite number of conserved (symmetric traceless) tensor currents. In a theory of a scalar field of dimension D-2 they were demonstrated to be generated by bilocal normal products of free massless scalar fields with an O(N), U(N), or Sp(2N) (global) gauge symmetry [B. Bakalov, N. M. Nikolov, K.-H. Rehren, and I. Todorov, 'Unitary positive energy representations of scalar bilocal fields,' Commun. Math. Phys. 271, 223-246 (2007); e-print arXiv:math-ph/0604069v3; and 'Infinite dimensional Lie algebras in 4D conformal quantum field theory,' J. Phys. A Math Theor. 41, 194002 (2008); e-print arXiv:0711.0627v2 [hep-th
Some characterizations of quantum channel in infinite Hilbert spaces
Sun, Xiu-Hong; Li, Yuan
2014-05-15
We first show that for any quantum states ρ on H and σ on K there exists a quantum channel Φ such that Φ(ρ) = σ, where H and K are finite or infinite dimensional Hilbert spaces. Then we consider some conclusions for the quantum channel Φ such that Φ(ρ) = σ and Φ(I{sub H}) exists or Φ(I{sub H})=I{sub K}.
Analysis of Multiple Cracks in an Infinite Functionally Graded Plate
NASA Technical Reports Server (NTRS)
Shbeeb, N. I.; Binienda, W. K.; Kreider, K. L.
1999-01-01
A general methodology was constructed to develop the fundamental solution for a crack embedded in an infinite non-homogeneous material in which the shear modulus varies exponentially with the y coordinate. The fundamental solution was used to generate a solution to fully interactive multiple crack problems for stress intensity factors and strain energy release rates. Parametric studies were conducted for two crack configurations. The model displayed sensitivity to crack distance, relative angular orientation, and to the coefficient of nonhomogeneity.
Infinite Simple 3d Cubic Network of Identical Capacitors
NASA Astrophysics Data System (ADS)
Asad, Jihad H.
2013-06-01
In this paper, the effective capacitance between the origin (0, 0, 0) and any other lattice site (l1, l2, l3), in an infinite simple cubic (SC) network consisting of identical capacitors each of capacitance C, has been expressed rationally in terms of the known value go and π. The asymptotic behavior is also investigated, and some numerical values for the effective capacitance are presented.
Helium Dilution Cryocooler for Space Applications
NASA Technical Reports Server (NTRS)
Roach, Pat; Hogan, Robert (Technical Monitor)
2001-01-01
NASA's New Millenium Program Space Technology presents the Helium Dilution Cryocooler for Space Applications. The topics include: 1) Capability; 2) Applications; and 3) Advantages. This paper is in viewgraph form.
Rheology of Dilute Aqueous Dispersions of Monodisperse Phytoglycogen Nanoparticles
NASA Astrophysics Data System (ADS)
Shamana, Hurmiz; Dutcher, John
The viscosity of dilute colloidal dispersions is well described by the Einstein relation, which is linear in the volume fraction of the particles. For hard spheres, this allows the calculation of the specific volume of the spheres. For soft colloidal particles, the analysis of the data can be complicated by the uptake of the solvent by the particles. We have measured the concentration dependence of the zero shear viscosity of dilute aqueous dispersions of monodisperse phytoglycogen nanoparticles, which absorb a large amount of water (each nanoparticle contains about 250% of its mass in water). By using values of the particle size and the hydrated and dehydrated molecular weights determined using neutron scattering, we can interpret the measured viscosity-concentration data in terms of the Einstein relation to obtain the particle density and corresponding volume fraction of the dispersions.
Infinite variance in fermion quantum Monte Carlo calculations
NASA Astrophysics Data System (ADS)
Shi, Hao; Zhang, Shiwei
2016-03-01
For important classes of many-fermion problems, quantum Monte Carlo (QMC) methods allow exact calculations of ground-state and finite-temperature properties without the sign problem. The list spans condensed matter, nuclear physics, and high-energy physics, including the half-filled repulsive Hubbard model, the spin-balanced atomic Fermi gas, and lattice quantum chromodynamics calculations at zero density with Wilson Fermions, and is growing rapidly as a number of problems have been discovered recently to be free of the sign problem. In these situations, QMC calculations are relied on to provide definitive answers. Their results are instrumental to our ability to understand and compute properties in fundamental models important to multiple subareas in quantum physics. It is shown, however, that the most commonly employed algorithms in such situations have an infinite variance problem. A diverging variance causes the estimated Monte Carlo statistical error bar to be incorrect, which can render the results of the calculation unreliable or meaningless. We discuss how to identify the infinite variance problem. An approach is then proposed to solve the problem. The solution does not require major modifications to standard algorithms, adding a "bridge link" to the imaginary-time path integral. The general idea is applicable to a variety of situations where the infinite variance problem may be present. Illustrative results are presented for the ground state of the Hubbard model at half-filling.
Single file diffusion into a semi-infinite tube.
Farrell, Spencer G; Brown, Aidan I; Rutenberg, Andrew D
2015-01-01
We investigate single file diffusion (SFD) of large particles entering a semi-infinite tube, such as luminal diffusion of proteins into microtubules or flagella. While single-file effects have no impact on the evolution of particle density, we report significant single-file effects for individually tracked tracer particle motion. Both exact and approximate ordering statistics of particles entering semi-infinite tubes agree well with our stochastic simulations. Considering initially empty semi-infinite tubes, with particles entering at one end starting from an initial time t = 0, tracked particles are initially super-diffusive after entering the system, but asymptotically diffusive at later times. For finite time intervals, the ratio of the net displacement of individual single-file particles to the average displacement of untracked particles is reduced at early times and enhanced at later times. When each particle is numbered, from the first to enter (n = 1) to the most recent (n = N), we find good scaling collapse of this distance ratio for all n. Experimental techniques that track individual particles, or local groups of particles, such as photo-activation or photobleaching of fluorescently tagged proteins, should be able to observe these single-file effects. However, biological phenomena that depend on local concentration, such as flagellar extension or luminal enzymatic activity, should not exhibit single-file effects. PMID:26595123
Analysis of transitional separation bubbles on infinite swept wings
NASA Technical Reports Server (NTRS)
Davis, R. L.; Carter, J. E.
1986-01-01
A previously developed two-dimensional local inviscid-viscous interaction technique for the analysis of airfoil transitional separation bubbles, ALESEP (Airfoil Leading Edge Separation), has been extended for the calculation of transitional separation bubbles over infinite swept wings. As part of this effort, Roberts' empirical correlation, which is interpreted as a separated flow empirical extension of Mack's stability theory for attached flows, has been incorporated into the ALESEP procedure for the prediction of the transition location within the separation bubble. In addition, the viscous procedure used in the ALESEP techniques has been modified to allow for wall suction. A series of two-dimensional calculations is presented as a verification of the prediction capability of the interaction techniques with the Roberts' transition model. Numerical tests have shown that this two-dimensional natural transition correlation may also be applied to transitional separation bubbles over infinite swept wings. Results of the interaction procedure are compared with Horton's detailed experimental data for separated flow over a swept plate which demonstrates the accuracy of the present technique. Wall suction has been applied to a similar interaction calculation to demonstrate its effect on the separation bubble. The principal conclusion of this paper is that the prediction of transitional separation bubbles over two-dimensional or infinite swept geometries is now possible using the present interacting boundary layer approach.
Single file diffusion into a semi-infinite tube.
Farrell, Spencer G; Brown, Aidan I; Rutenberg, Andrew D
2015-11-23
We investigate single file diffusion (SFD) of large particles entering a semi-infinite tube, such as luminal diffusion of proteins into microtubules or flagella. While single-file effects have no impact on the evolution of particle density, we report significant single-file effects for individually tracked tracer particle motion. Both exact and approximate ordering statistics of particles entering semi-infinite tubes agree well with our stochastic simulations. Considering initially empty semi-infinite tubes, with particles entering at one end starting from an initial time t = 0, tracked particles are initially super-diffusive after entering the system, but asymptotically diffusive at later times. For finite time intervals, the ratio of the net displacement of individual single-file particles to the average displacement of untracked particles is reduced at early times and enhanced at later times. When each particle is numbered, from the first to enter (n = 1) to the most recent (n = N), we find good scaling collapse of this distance ratio for all n. Experimental techniques that track individual particles, or local groups of particles, such as photo-activation or photobleaching of fluorescently tagged proteins, should be able to observe these single-file effects. However, biological phenomena that depend on local concentration, such as flagellar extension or luminal enzymatic activity, should not exhibit single-file effects.
Single file diffusion into a semi-infinite tube
NASA Astrophysics Data System (ADS)
Farrell, Spencer G.; Brown, Aidan I.; Rutenberg, Andrew D.
2015-12-01
We investigate single file diffusion (SFD) of large particles entering a semi-infinite tube, such as luminal diffusion of proteins into microtubules or flagella. While single-file effects have no impact on the evolution of particle density, we report significant single-file effects for individually tracked tracer particle motion. Both exact and approximate ordering statistics of particles entering semi-infinite tubes agree well with our stochastic simulations. Considering initially empty semi-infinite tubes, with particles entering at one end starting from an initial time t = 0, tracked particles are initially super-diffusive after entering the system, but asymptotically diffusive at later times. For finite time intervals, the ratio of the net displacement of individual single-file particles to the average displacement of untracked particles is reduced at early times and enhanced at later times. When each particle is numbered, from the first to enter (n = 1) to the most recent (n = N), we find good scaling collapse of this distance ratio for all n. Experimental techniques that track individual particles, or local groups of particles, such as photo-activation or photobleaching of fluorescently tagged proteins, should be able to observe these single-file effects. However, biological phenomena that depend on local concentration, such as flagellar extension or luminal enzymatic activity, should not exhibit single-file effects.
Infinite slope stability under steady unsaturated seepage conditions
Lu, N.; Godt, J.
2008-01-01
[1] We present a generalized framework for the stability of infinite slopes under steady unsaturated seepage conditions. The analytical framework allows the water table to be located at any depth below the ground surface and variation of soil suction and moisture content above the water table under steady infiltration conditions. The framework also explicitly considers the effect of weathering and porosity increase near the ground surface on changes in the friction angle of the soil. The factor of safety is conceptualized as a function of the depth within the vadose zone and can be reduced to the classical analytical solution for subaerial infinite slopes in the saturated zone. Slope stability analyses with hypothetical sandy and silty soils are conducted to illustrate the effectiveness of the framework. These analyses indicate that for hillslopes of both sandy and silty soils, failure can occur above the water table under steady infiltration conditions, which is consistent with some field observations that cannot be predicted by the classical infinite slope theory. A case study of shallow slope failures of sandy colluvium on steep coastal hillslopes near Seattle, Washington, is presented to examine the predictive utility of the proposed framework. Copyright 2008 by the American Geophysical Union.
Infinite variance in fermion quantum Monte Carlo calculations.
Shi, Hao; Zhang, Shiwei
2016-03-01
For important classes of many-fermion problems, quantum Monte Carlo (QMC) methods allow exact calculations of ground-state and finite-temperature properties without the sign problem. The list spans condensed matter, nuclear physics, and high-energy physics, including the half-filled repulsive Hubbard model, the spin-balanced atomic Fermi gas, and lattice quantum chromodynamics calculations at zero density with Wilson Fermions, and is growing rapidly as a number of problems have been discovered recently to be free of the sign problem. In these situations, QMC calculations are relied on to provide definitive answers. Their results are instrumental to our ability to understand and compute properties in fundamental models important to multiple subareas in quantum physics. It is shown, however, that the most commonly employed algorithms in such situations have an infinite variance problem. A diverging variance causes the estimated Monte Carlo statistical error bar to be incorrect, which can render the results of the calculation unreliable or meaningless. We discuss how to identify the infinite variance problem. An approach is then proposed to solve the problem. The solution does not require major modifications to standard algorithms, adding a "bridge link" to the imaginary-time path integral. The general idea is applicable to a variety of situations where the infinite variance problem may be present. Illustrative results are presented for the ground state of the Hubbard model at half-filling. PMID:27078480
Debye series of normally incident plane-wave scattering by an infinite multilayered cylinder.
Li, Renxian; Han, Xiang'e; Jiang, Huifen; Ren, Kuan Fang
2006-08-20
We derive the formula of the Debye-series decomposition for normally incident plane-wave scattering by an infinite multilayered cylinder. A comparison of the scattering diagrams calculated by the Debye series and Mie theory for a graded-index polymer optical fiber is given and the agreement is found to be satisfied. This approach permits us to simulate the rainbow intensity distribution of any single order and the interference of several orders, which is of good use to the study of the scattering characteristics of an inhomogeneous cylinder and to the measurement of the refractive index profile of an inhomogeneous cylinder. PMID:16892131
Fuhrman, Marco Hu, Ying
2007-09-15
In this paper we prove the existence of a solution to backward stochastic differential equations in infinite dimensions with continuous driver under various assumptions. We apply our results to a stochastic game problem with infinitely many players.
Flux balance analysis accounting for metabolite dilution.
Benyamini, Tomer; Folger, Ori; Ruppin, Eytan; Shlomi, Tomer
2010-01-01
Flux balance analysis is a common method for predicting steady-state flux distributions within metabolic networks, accounting for the growth demand for the synthesis of a predefined set of essential biomass precursors. Ignoring the growth demand for the synthesis of intermediate metabolites required for balancing their dilution leads flux balance analysis to false predictions in some cases. Here, we present metabolite dilution flux balance analysis, which addresses this problem, resulting in improved metabolic phenotype predictions. PMID:20398381
Flux balance analysis accounting for metabolite dilution.
Benyamini, Tomer; Folger, Ori; Ruppin, Eytan; Shlomi, Tomer
2010-01-01
Flux balance analysis is a common method for predicting steady-state flux distributions within metabolic networks, accounting for the growth demand for the synthesis of a predefined set of essential biomass precursors. Ignoring the growth demand for the synthesis of intermediate metabolites required for balancing their dilution leads flux balance analysis to false predictions in some cases. Here, we present metabolite dilution flux balance analysis, which addresses this problem, resulting in improved metabolic phenotype predictions.
DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS
Kishore K. Mohanty
2005-01-01
There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. Imbibition in an originally oil-wet 2D capillary is the fastest in the case of Alf-38 and slowest in the case of DTAB (among the surfactants studied). Force of adhesion studies and contact angle measurements show that greater wettability alteration is possible with these anionic surfactants than the cationic surfactant studied. The water imbibition rate does not increase monotonically with an increase in the surfactant concentration. A numerical model has been developed that fits the rate of imbibition. Plans for the next quarter include conducting simulation and imbibition studies.
Estimation method for serial dilution experiments.
Ben-David, Avishai; Davidson, Charles E
2014-12-01
Titration of microorganisms in infectious or environmental samples is a corner stone of quantitative microbiology. A simple method is presented to estimate the microbial counts obtained with the serial dilution technique for microorganisms that can grow on bacteriological media and develop into a colony. The number (concentration) of viable microbial organisms is estimated from a single dilution plate (assay) without a need for replicate plates. Our method selects the best agar plate with which to estimate the microbial counts, and takes into account the colony size and plate area that both contribute to the likelihood of miscounting the number of colonies on a plate. The estimate of the optimal count given by our method can be used to narrow the search for the best (optimal) dilution plate and saves time. The required inputs are the plate size, the microbial colony size, and the serial dilution factors. The proposed approach shows relative accuracy well within ±0.1log10 from data produced by computer simulations. The method maintains this accuracy even in the presence of dilution errors of up to 10% (for both the aliquot and diluent volumes), microbial counts between 10(4) and 10(12) colony-forming units, dilution ratios from 2 to 100, and plate size to colony size ratios between 6.25 to 200.
21 CFR 862.2750 - Pipetting and diluting system for clinical use.
Code of Federal Regulations, 2014 CFR
2014-04-01
... diluting system for clinical use is a device intended to provide an accurately measured volume of liquid at a specified temperature for use in certain test procedures. This generic type of device...
Volumetric Properties of Dilute Aqueous Solutions of 1- and 2-propanol to 50 MPa and 373.15 K
NASA Astrophysics Data System (ADS)
Seitz, J.; Bahramian, J.; Blackwell, R.; Inaki, T.; York, D.; Schulte, M. D.
2014-12-01
The need to accurately model and understand reactions among organic compounds and biomolecules in solution is necessary to develop realistic chemical models for the reactions leading to the emergence of life and metabolic processes of extremophiles under elevated temperature and pressure conditions. Unfortunately, the scarcity of experimentally determined volumetric (and other) properties for important compounds at high temperatures and pressures leads to uncertainty in the calculation of reaction properties. Experimentally determined volumetric properties of aqueous solutions at non-standard conditions provide direct tests of current estimation methods and aid in the refinement of these methods. The goal of our research is to provide a database of experimentally determined volumetric properties. In previous studies, we have examined important organic molecules and biomolecules such as adenosine, coenzyme M and D-ribose. In this study, we investigate the volumetric properties of the structural isomers 1- and 2-propanol. 1-propanol (n-propanol) is a primary alcohol (CH3CH2CH2OH) and 2-propanol (isopropanol) is the simplest example of a secondary alcohol (CH3CHOHCH3). These compounds differ slightly in structure depending on to which carbon atom the hydroxyl group is bonded and will provide a sensitive test of current estimation methods and lead to more accurate predictions of the properties of complex aqueous systems at elevated temperatures and pressures. We obtained the densities of aqueous solutions of the alchohols using an Anton Paar DMA HP vibrating tube densimeter. Pressure was measured (pressure transducer) to an accuracy of ±0.01% and temperature was measured (integrated platinum thermometer) with an accuracy of ±0.05 K. Experimental uncertainty of density measurements is less than ±0.0001 g·cm-3. The partial molar volumes at infinite dilution (V∞) for 1- and 2-propanol were calculated from the measured densities and are shown in the figure at 0
Dilute oxygen combustion. Phase I report
1997-10-01
A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NO{sub x}) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NO{sub x} through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NO{sub x} production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature ({approximately}1366 K) oxidant (7-27% O{sub 2} vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d{sup +} scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d{sup +} scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW ({approximately}0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric
Dilute Oxygen Combustion Phase 2 Final Report
Ryan, H.M.; Riley, M.F.; Kobayashi, H.
2005-09-30
A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NOx production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature (~1366 K) oxidant (7-27% O2 vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d+ scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d+ scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW (~0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NOx emissions
Dilute Oxygen Combustion Phase I Final Report
Ryan, H.M.; Riley, M.F.; Kobayashi, H.
1997-10-31
A novel burner, in which fuel (natural gas) and oxidant (oxygen or air) are separately injected into a furnace, shows promise for achieving very low nitrogen oxide(s) (NOx) emissions for commercial furnace applications. The dilute oxygen combustion (DOC) burner achieves very low NOx through in-furnace dilution of the oxidant stream prior to combustion, resulting in low flame temperatures, thus inhibiting thermal NOx production. The results of a fundamental and applied research effort on the development of the DOC burner are presented. In addition, the results of a market survey detailing the potential commercial impact of the DOC system are disclosed. The fundamental aspects of the burner development project involved examining the flame characteristics of a natural gas turbulent jet in a high-temperature (~1366 K) oxidant (7-27% O2 vol. wet). Specifically, the mass entrainment rate, the flame lift-off height, the velocity field and major species field of the jet were evaluated as a function of surrounding-gas temperature and composition. The measured entrainment rate of the fuel jet decreased with increasing oxygen content in the surrounding high-temperature oxidant, and was well represented by the d+ scaling correlation found in the literature. The measured flame lift-off height decreased with increasing oxygen content and increasing temperature of the surrounding gas. An increase in surrounding-gas oxygen content and/or temperature inhibited the velocity decay within the jet periphery as a function of axial distance as compared to isothermal turbulent jets. However, the velocity measurements were only broadly represented by the d+ scaling correlation. Several DOC burner configurations were tested in a laboratory-scale furnace at a nominal firing rate of 185 kW (~0.63 MMBtu/h). The flue gas composition was recorded as a function of furnace nitrogen content, furnace temperature, burner geometric arrangement, firing rate, and fuel injection velocity. NOx emissions
Effect of dilution on compressibility of naproxen in acetonitrile studied by ultrasonic method
NASA Astrophysics Data System (ADS)
Marczak, W.; Kowalska, T.; Bucek, M.; Piotrowski, D.; Sajewicz, M.
2006-11-01
Naproxen, ibuprofen, and ketoprofen are non-steroidal anti-inflammatory drugs. All of them belong to chiral 2-arylpropionic acids (2-APAs). Chiral compounds may remain in a patient's body as two antimers, even if administered as a single one, due to transenantiomerization. That is dangerous if therapeutic enantiomer has a toxic antipode. Chromatographic data suggest that solutions of S-(+)-naproxen in acetonitrile are stiffer than the pure solvent that favours oscillatory transenantiomerisation. Acoustic and volumetric studies of dilute solutions of naproxen in acetonitrile have been undertaken to verify that supposition. The molar adiabatic compressibility and volume depend linearly on the molar percent of naproxen at temperatures from 298.15 K to 313.15 K. Limiting partial compressibility of naproxen is close to zero and decreases slightly with increasing temperature. Thus, the compressibility of dilute solutions is mainly due to compressibility of acetonitrile, while naproxen is virtually incompressible. The hydrogen-bonded dimers of naproxen probably remain intact, even at infinite dilution.
Fluorescence and absorbance of polystyrene in dilute and semidilute solutions
Torkelson, J.M.; Lipsky, S.; Tirrell, M.; Tirrell, D.A.
1983-02-01
The fluorescence and absorbance of polystyrene in solution have been measured over a wide concentration range for several molecular weights and solvents (cyclohexane, 1,2 dichloroethane). The absorbance at wavelengths below 280 nm for these molecular weights and solvents is found to be insensitive to the transition between dilute and semidilute solutions. Self-absorption of the fluorescence results in a much reduced observed monomer emission at high concentration. When this is corrected, the ratio of excimer to monomer fluorescence intensity, I/sub E//I/sub M/, is essentially constant at low concentrations and at most increases only very slowly and smoothly at higher concentrations. No significant molecular weight or solvent effects on the concentration dependence of I/sub E//I/sub M/ are manifested for these molecular weights and solvents over the concentration range studied. Contrary to previous reports, fluorescence spectroscopy reveals no abrupt transition between dilute and semidilute solutions. 30 references, 6 figures, 4 tables.
Molecular dissociation in dilute gas
Renfrow, S.N.; Duggan, J.L.; McDaniel, F.D. |
1999-06-01
The charge state distributions (CSD) produced during molecular dissociation are important to both Trace Element Accelerator Mass Spectrometry (TEAMS) and the ion implantation industry. The CSD of 1.3{endash}1.7 MeV SiN{sup +}, SiMg{sup +}, SiMn{sup +}, and SiZn{sup +} molecules have been measured for elements that do not form atomic negative ions (N, Mg, Mn, and Zn) using a NEC Tandem Pelletron accelerator. The molecules were produced in a Cs sputter negative ion source, accelerated, magnetically analyzed, and then passed through an N{sub 2} gas cell. The neutral and charged breakups where analyzed using an electrostatic deflector and measured with particle detectors. Equilibrium CSD were determined and comparisons made between molecular and atomic ion data. {copyright} {ital 1999 American Institute of Physics.}
Modeling of dilution jet flowfields
NASA Technical Reports Server (NTRS)
Holdeman, J. D.; Srinivasan, R.
1984-01-01
The present paper will compare temperature field measurements from selected cases in these investigations with distributions calculated with an empirical model based on assumed vertical profile similarity and superposition and with a 3-D elliptic code using a standard K-E turbulence model. The results will show the capability (or lack thereof) of the models to predict the effects of the principle flow and geometric variables.
Declining ecosystem health and the dilution effect.
Khalil, Hussein; Ecke, Frauke; Evander, Magnus; Magnusson, Magnus; Hörnfeldt, Birger
2016-01-01
The "dilution effect" implies that where species vary in susceptibility to infection by a pathogen, higher diversity often leads to lower infection prevalence in hosts. For directly transmitted pathogens, non-host species may "dilute" infection directly (1) and indirectly (2). Competitors and predators may (1) alter host behavior to reduce pathogen transmission or (2) reduce host density. In a well-studied system, we tested the dilution of the zoonotic Puumala hantavirus (PUUV) in bank voles (Myodes glareolus) by two competitors and a predator. Our study was based on long-term PUUV infection data (2003-2013) in northern Sweden. The field vole (Microtus agrestis) and the common shrew (Sorex araneus) are bank vole competitors and Tengmalm's owl (Aegolius funereus) is a main predator of bank voles. Infection probability in bank voles decreased when common shrew density increased, suggesting that common shrews reduced PUUV transmission. Field voles suppressed bank vole density in meadows and clear-cuts and indirectly diluted PUUV infection. Further, Tengmalm's owl decline in 1980-2013 may have contributed to higher PUUV infection rates in bank voles in 2003-2013 compared to 1979-1986. Our study provides further evidence for dilution effect and suggests that owls may have an important role in reducing disease risk. PMID:27499001
J-integral estimates for cracks in infinite bodies
NASA Technical Reports Server (NTRS)
Dowling, N. E.
1986-01-01
An analysis and discussion is presented of existing estimates of the J-integral for cracks in infinite bodies. Equations are presented which provide convenient estimates for Ramberg-Osgood type elastoplastic materials containing cracks and subjected to multiaxial loading. The relationship between J and the strain normal to the crack is noted to be only weakly dependent on state of stress. But the relationship between J and the stress normal to the crack is strongly dependent on state of stress. A plastic zone correction term often employed is found to be arbitrary, and its magnitude is seldom significant.
Approximate Controllability of Fractional Neutral Stochastic System with Infinite Delay
NASA Astrophysics Data System (ADS)
Sakthivel, R.; Ganesh, R.; Suganya, S.
2012-12-01
The concept of controllability plays an important role in analysis and design of linear and nonlinear control systems. Further, fractional differential equations have wide applications in engineering and science. In this paper, the approximate controllability of neutral stochastic fractional integro-differential equation with infinite delay in a Hilbert space is studied. By using Krasnoselskii's fixed point theorem with stochastic analysis theory, we derive a new set of sufficient conditions for the approximate controllability of nonlinear fractional stochastic system under the assumption that the corresponding linear system is approximately controllable. Finally, an example is provided to illustrate the obtained theory.
Spin transport of weakly disordered Heisenberg chain at infinite temperature
NASA Astrophysics Data System (ADS)
Khait, Ilia; Gazit, Snir; Yao, Norman Y.; Auerbach, Assa
2016-06-01
We study the disordered Heisenberg spin chain, which exhibits many-body localization at strong disorder, in the weak to moderate disorder regime. A continued fraction calculation of dynamical correlations is devised, using a variational extrapolation of recurrents. Good convergence for the infinite chain limit is shown. We find that the local spin correlations decay at long times as C ˜t-β , whereas the conductivity exhibits a low-frequency power law σ ˜ωα . The exponents depict subdiffusive behavior β <1 /2 ,α >0 at all finite disorders and convergence to the scaling result α +2 β =1 at large disorders.
Rotor-router walk on a semi-infinite cylinder
NASA Astrophysics Data System (ADS)
Papoyan, Vl V.; Poghosyan, V. S.; Priezzhev, V. B.
2016-07-01
We study the rotor-router walk with the clockwise ordering of outgoing edges on the semi-infinite cylinder. Imposing uniform conditions on the boundary of the cylinder, we consider growth of the cluster of visited sites and its internal structure. The average width of the surface region of the cluster evolves with time to the stationary value by a scaling law whose parameters are close to the standard KPZ exponents. We introduce characteristic labels corresponding to closed clockwise contours formed by rotors and show that the sequence of labels has in average an ordered helix structure.
Infinite impulse response modal filtering in visible adaptive optics
NASA Astrophysics Data System (ADS)
Agapito, G.; Arcidiacono, C.; Quirós-Pacheco, F.; Puglisi, A.; Esposito, S.
2012-07-01
Diffraction limited resolution adaptive optics (AO) correction in visible wavelengths requires a high performance control. In this paper we investigate infinite impulse response filters that optimize the wavefront correction: we tested these algorithms through full numerical simulations of a single-conjugate AO system comprising an adaptive secondary mirror with 1127 actuators and a pyramid wavefront sensor (WFS). The actual practicability of the algorithms depends on both robustness and knowledge of the real system: errors in the system model may even worsen the performance. In particular we checked the robustness of the algorithms in different conditions, proving that the proposed method can reject both disturbance and calibration errors.
Drug susceptibility testing by dilution methods.
Jeannot, Katy; Plésiat, Patrick
2014-01-01
Serial twofold dilution methods are widely used to assess the bacteriostatic activities of antibiotics. This can be achieved by dilution of considered drugs in agar medium or in culture broth, and inoculation by calibrated inoculums. Although seemingly simple, these methods are greatly influenced by the experimental conditions used and may lead to discrepant results, in particular with untrained investigators. The present step-by-step protocol has been validated for Pseudomonas species, including P. aeruginosa. Introduction of appropriate control strains is crucial to ascertain minimal inhibitory concentration values and compare the results of independent experiments.
Diluted magnetic semiconductor nanowires exhibiting magnetoresistance
Yang, Peidong; Choi, Heonjin; Lee, Sangkwon; He, Rongrui; Zhang, Yanfeng; Kuykendal, Tevye; Pauzauskie, Peter
2011-08-23
A method for is disclosed for fabricating diluted magnetic semiconductor (DMS) nanowires by providing a catalyst-coated substrate and subjecting at least a portion of the substrate to a semiconductor, and dopant via chloride-based vapor transport to synthesize the nanowires. Using this novel chloride-based chemical vapor transport process, single crystalline diluted magnetic semiconductor nanowires Ga.sub.1-xMn.sub.xN (x=0.07) were synthesized. The nanowires, which have diameters of .about.10 nm to 100 nm and lengths of up to tens of micrometers, show ferromagnetism with Curie temperature above room temperature, and magnetoresistance up to 250 Kelvin.
Jet fuel deposition and oxidation: Dilution, materials, oxygen, and temperature effects
Zabarnick, S.; Zelesnik, P.; Grinstead, R.R.
1996-04-01
Quartz crystal microbalance (QCM) and pressure measurements are used for determination of jet fuel thermal stability in a batch reactor. The QCM is able to monitor extremely small amounts of deposition in situ, while the pressure measurements provide qualitative data on the oxidation process. The dependence of the deposition amount was monitored as a function of the oxygen availability for two fuels. Also, the effect of QCM electrode materials was investigated. Deposition and oxidation were compared for the following electrode materials: gold, aluminum, silver, and platinum. The authors also studied the effect of dilution on oxidation and deposition. Jet fuel was diluted with increasing amounts of hydrocarbon solvent. It was observed that this dilution procedure can help characterize a fuel`s effective antioxidant concentration. Fuel dilution is also shown to be a good technique for improving thermal stability characteristics of poor fuels. Additionally they have studied the temperature effect on deposition for two fuels over the range 140 to 180 C.
Conformal field theories with infinitely many conservation laws
NASA Astrophysics Data System (ADS)
Todorov, Ivan
2013-02-01
Globally conformal invariant quantum field theories in a D-dimensional space-time (D even) have rational correlation functions and admit an infinite number of conserved (symmetric traceless) tensor currents. In a theory of a scalar field of dimension D-2 they were demonstrated to be generated by bilocal normal products of free massless scalar fields with an O(N), U(N), or Sp(2N) (global) gauge symmetry [B. Bakalov, N. M. Nikolov, K.-H. Rehren, and I. Todorov, "Unitary positive energy representations of scalar bilocal fields," Commun. Math. Phys. 271, 223-246 (2007), 10.1007/s00220-006-0182-2; e-print arXiv:math-ph/0604069v3; B. Bakalov, N. M. Nikolov, K.-H. Rehren, and I. Todorov, "Infinite dimensional Lie algebras in 4D conformal quantum field theory," J. Phys. A Math Theor. 41, 194002 (2008), 10.1088/1751-8113/41/19/194002; e-print arXiv:0711.0627v2 [hep-th
Infinite Factorial Unbounded-State Hidden Markov Model.
Valera, Isabel; Ruiz, Francisco J R; Perez-Cruz, Fernando
2016-09-01
There are many scenarios in artificial intelligence, signal processing or medicine, in which a temporal sequence consists of several unknown overlapping independent causes, and we are interested in accurately recovering those canonical causes. Factorial hidden Markov models (FHMMs) present the versatility to provide a good fit to these scenarios. However, in some scenarios, the number of causes or the number of states of the FHMM cannot be known or limited a priori. In this paper, we propose an infinite factorial unbounded-state hidden Markov model (IFUHMM), in which the number of parallel hidden Markovmodels (HMMs) and states in each HMM are potentially unbounded. We rely on a Bayesian nonparametric (BNP) prior over integer-valued matrices, in which the columns represent the Markov chains, the rows the time indexes, and the integers the state for each chain and time instant. First, we extend the existent infinite factorial binary-state HMM to allow for any number of states. Then, we modify this model to allow for an unbounded number of states and derive an MCMC-based inference algorithm that properly deals with the trade-off between the unbounded number of states and chains. We illustrate the performance of our proposed models in the power disaggregation problem. PMID:26571511
Spectra of Semi-Infinite Quantum Graph Tubes
NASA Astrophysics Data System (ADS)
Shipman, Stephen P.; Tillay, Jeremy
2016-10-01
The spectrum of a semi-infinite quantum graph tube with square period cells is analyzed. The structure is obtained by rolling up a doubly periodic quantum graph into a tube along a period vector and then retaining only a semi-infinite half of the tube. The eigenfunctions associated to the spectrum of the half-tube involve all Floquet modes of the full tube. This requires solving the complex dispersion relation {D(λ,k_1,k_2)=0} with {(k_1,k_2)in({C}/2π{Z})^2} subject to the constraint {a k_1 + b k_2 ≡ 0} (mod {2π}), where a and b are integers. The number of Floquet modes for a given {λin{R}} is {2max{ a, b }}. Rightward and leftward modes are determined according to an indefinite energy flux form. The spectrum may contain eigenvalues that depend on the boundary conditions, and some eigenvalues may be embedded in the continuous spectrum.
Masses of atomic nuclei in the infinite nuclear matter model
Satpathy, L.; Nayak, R.C.
1988-07-01
We present mass excesses of 3481 nuclei in the range 18less than or equal toAless than or equal to267 using the infinite nuclear matter model based on the Hugenholtz-Van Hove theorem. In this model the ground-state energy of a nucleus of asymmetry ..beta.. is considered equivalent to the energy of a perfect sphere made up of the infinite nuclear matter of the same asymmetry plus the residual energy due to shell effects, deformation, etc., called the local energy eta. In this model there are two kinds of parameters: global and local. The five global parameters characterizing the properties of the above sphere are determined by fitting the mass of all nuclei (756) in the recent mass table of Wapstra et al. having error bar less than 30 keV. The local parameters are determined for 25 regions each spanning 8 or 10 A values. The total number of parameters including the five global ones is 238. The root-mean-square deviation for the calculated masses from experiment is 397 keV for the 1572 nuclei used in the least-squares fit. copyright 1988 Academic Press, Inc.
NASA Technical Reports Server (NTRS)
Bensoussan, A.; Delfour, M. C.; Mitter, S. K.
1976-01-01
Available published results are surveyed for a special class of infinite-dimensional control systems whose evolution is characterized by a semigroup of operators of class C subscript zero. Emphasis is placed on an approach that clarifies the system-theoretic relationship among controllability, stabilizability, stability, and the existence of a solution to an associated operator equation of the Riccati type. Formulation of the optimal control problem is reviewed along with the asymptotic behavior of solutions to a general system of equations and several theorems concerning L2 stability. Examples are briefly discussed which involve second-order parabolic systems, first-order hyperbolic systems, and distributed boundary control.
Dilution control and vibration studies at an underground mine
Mohanty, B. |; Yang, R.; Leblanc, M.; Kelly, C.
1995-12-31
A total of 33 blasts in the pillar recovery program at INCO-Crean Hill has been investigated by means of an extensive set of diagnostic techniques. These included, borehole deviation measurements, stope cavity survey, near-field seismics in both rock and backfill, in-hole VOD and fragment size analysis. The 200 mm diameter VCR blasts employed a variety of explosives types (ANFO, slurry and ANFO/Polystyrene) and deck sizes. The objective of the investigation was to control dilution and backbreak through optimal choice of explosive type and charge weight, without exceeding vibration limits in the adjacent backfill or causing significant degradation in fragmentation. The high quality experimental data, along with closely monitored borehole deviations and in-hole detonation properties of the explosive decks allowed the establishment of comprehensive near-field vibration vs. scaled distance relationship in both rock and backfill. The study helped identify the principal factors responsible for dilution from backfill at the mine. The analysis also showed that the two types of slurry explosive used in the mine and regular ANFO had equivalent damage potential to backfill. The key conclusions of the study were further confirmed in a second pillar recovery program, with significant potential benefits in terms of both dilution control and increased productivity. The paper details the steps in this investigation, and highlights the strengths and limitations of the methodology adopted in solving blasting problems in full-scale production blast environment.
Dry dilution refrigerator with He-4 precool loop
Uhlig, Kurt
2014-01-29
He-3/He-4 dilution refrigerators (DR) are very common in sub-Kelvin temperature research. We describe a pulse tube precooled DR where a separate He-4 circuit condenses the He-3 of the dilution loop. Whereas in our previous work the dilution circuit and the He-4 circuit were separate, we show how the two circuits can be combined. Originally, the He-4 loop with a base temperature of ∼ 1 K was installed to make an additional cooling power of up to 100 mW available to cool cold amplifiers and electrical lines. In the new design, the dilution circuit is run through a heat exchanger in the vessel of the He-4 circuit so condensation of the He-3 stream of the DR is done by the He-4 stage. A much reduced condensation time (factor of 2) of the He-3/He-4 gas mixture at the beginning of an experiment is achieved. A compressor is no longer needed with the DR as the condensation pressure remains below atmospheric pressure at all times; thus the risk of losing expensive He-3 gas is small. The performance of the DR has been improved compared to previous work: The base temperature of the mixing chamber at a small He-3 flow rate is now 4.1 mK; at the highest He-3 flow rate of 1.2 mmol/s this temperature increases to 13 mK. Mixing chamber temperatures were measured with a cerium magnesium nitrate (CMN) thermometer which was calibrated with a superconducting fixed point device.
Ignition and Unburned Hydrogen Escaping from Hydrogen Diffusion Jet Flame Diluted with Nitrogen
Tran, P.X.; Soong, Yee
2007-07-01
Ignition and unburned hydrogen escaping from hydrogen jet diffusion flames diluted with nitrogen up to 70% were experimentally studied. The successful ignition locations were about 2/3 of the flame length above the jet exit for undiluted flames and moved much closer to the exit for diluted flames. For higher levels of dilution or higher flow rates, there existed a region within which a diluted hydrogen diffusion flame can be ignited and burns with a stable liftoff height. This is contrary to previous findings that pure and diluted hydrogen jet diffusion cannot achieve a stable lifted flame configuration. With liftoff, the flame is noisy and short with significant amount of unburned hydrogen escaping into the product gases. If ignition is initiated below this region, the flame propagates upstream quickly and attaches to the burner rim. Results from measurements of unburned hydrogen in the combustion products showed that the amount of unburned hydrogen increased as the nitrogen dilution level was increased. Thus, hydrogen diffusion flame diluted with nitrogen cannot burn completely.
Serial dilution microchip for cytotoxicity test
NASA Astrophysics Data System (ADS)
Bang, Hyunwoo; Lim, Sun Hee; Lee, Young Kyung; Chung, Seok; Chung, Chanil; Han, Dong-Chul; Chang, Jun Keun
2004-08-01
Today's pharmaceutical industry is facing challenges resulting from the vast increases in sample numbers produced by high-throughput screening (HTS). In addition, the bottlenecks created by increased demand for cytotoxicity testing (required to assess compound safety) are becoming a serious problem. We have developed a polymer PDMS (polydimethylsiloxane) based microfluidic device that can perform a cytotoxicity test in a rapid and reproducible manner. The concept that the device includes is well adjustable to automated robots in huge HTS systems, so we can think of it as a potential dilution and delivery module. Cytotoxicity testing is all about the dilution and dispensing of a drug sample. Previously, we made a PDMS based microfluidic device which automatically and precisely diluted drugs with a buffer solution with serially increasing concentrations. This time, the serially diluted drug solution was directly delivered to 96 well plates for cytotoxicity testing. Cytotoxic paclitaxel solution with 2% RPMI 1640 has been used while carrying out cancerous cell based cytotoxicity tests. We believe that this rapid and robust use of the PDMS microchip will overcome the growing problem in cytotoxicity testing for HTS.
Declining ecosystem health and the dilution effect
Khalil, Hussein; Ecke, Frauke; Evander, Magnus; Magnusson, Magnus; Hörnfeldt, Birger
2016-01-01
The “dilution effect” implies that where species vary in susceptibility to infection by a pathogen, higher diversity often leads to lower infection prevalence in hosts. For directly transmitted pathogens, non-host species may “dilute” infection directly (1) and indirectly (2). Competitors and predators may (1) alter host behavior to reduce pathogen transmission or (2) reduce host density. In a well-studied system, we tested the dilution of the zoonotic Puumala hantavirus (PUUV) in bank voles (Myodes glareolus) by two competitors and a predator. Our study was based on long-term PUUV infection data (2003–2013) in northern Sweden. The field vole (Microtus agrestis) and the common shrew (Sorex araneus) are bank vole competitors and Tengmalm’s owl (Aegolius funereus) is a main predator of bank voles. Infection probability in bank voles decreased when common shrew density increased, suggesting that common shrews reduced PUUV transmission. Field voles suppressed bank vole density in meadows and clear-cuts and indirectly diluted PUUV infection. Further, Tengmalm’s owl decline in 1980–2013 may have contributed to higher PUUV infection rates in bank voles in 2003–2013 compared to 1979–1986. Our study provides further evidence for dilution effect and suggests that owls may have an important role in reducing disease risk. PMID:27499001
Osmosis is not driven by water dilution.
Kramer, Eric M; Myers, David R
2013-04-01
There is a misconception among plant scientists that osmosis is driven by the tendency of solutes to dilute water. In this opinion article, we discuss the quantitative and qualitative failures of this view, and go on to review the correct kinetic picture of osmosis as it appears in physics textbooks.
Analysis of an infinite array of rectangular microstrip patches with idealized probe feeds
NASA Technical Reports Server (NTRS)
Pozar, D. M.; Schaubert, D. H.
1984-01-01
A solution is presented to the problem of an infinite array of microstrip patches fed by idealized current probes. The input reflection coefficient is calculated versus scan angle in an arbitrary scan plane, and the effects of substrate parameters and grid spacing are considered. It is pointed out that even when a Galerkin method is used the impedance matrix is not symmetric due to phasing through a unit cell, as required for scanning. The mechanism by which scan blindness can occur is discussed. Measurement results are presented for the reflection coefficient magnitude variation with angle for E-plane, H-plane, and D-plane scans, for various substrate parameters. Measured results from waveguide simulators are also presented, and the scan blindness phenomenon is observed and discussed in terms of forced surface waves and a modified grating lobe diagram.
Wang, R T; van de Hulst, H C
1995-05-20
A new algorithm for cylindrical Bessel functions that is similar to the one for spherical Bessel functions allows us to compute scattering functions for infinitely long cylinders covering sizes ka = 2πa/λ up to 8000 through the use of only an eight-digit single-precision machine computation. The scattering function and complex extinction coefficient of a finite cylinder that is seen near perpendicular incidence are derived from those of an infinitely long cylinder by the use of Huygens's principle. The result, which contains no arbitrary normalization factor, agrees quite well with analog microwave measurements of both extinction and scattering for such cylinders, even for an aspect ratio p = l/(2a) as low as 2. Rainbows produced by cylinders are similar to those for spherical drops but are brighter and have a lower contrast. PMID:21052428
Casimir energy of a semi-circular infinite cylinder
NASA Astrophysics Data System (ADS)
Nesterenko, V. V.; Lambiase, G.; Scarpetta, G.
2001-05-01
The Casimir energy of a semi-circular cylindrical shell is calculated by making use of the zeta function technique. This shell is obtained by crossing an infinite circular cylindrical shell by a plane passing through the symmetry axes of the cylinder and by considering only half of this configuration. All the surfaces, including the cutting plane, are assumed to be perfectly conducting. The zeta functions for scalar massless fields obeying the Dirichlet and Neumann boundary conditions on the semi-circular cylinder are constructed exactly. The sum of these zeta functions gives the zeta function for the electromagnetic field in question. The relevant plane problem is considered also. In all the cases the final expressions for the corresponding Casimir energies contain the pole contributions which are the consequence of the edges or corners in the boundaries. This implies that further renormalization is needed in order for the finite physical values for vacuum energy to be obtained for given boundary conditions.
Multilocus models in the infinite island model of population structure.
Roze, Denis; Rousset, François
2008-06-01
Different methods have been developed to consider the effects of statistical associations among genes that arise in population genetics models: kin selection models deal with associations among genes present in different interacting individuals, while multilocus models deal with associations among genes at different loci. It was pointed out recently that these two types of models are very similar in essence. In this paper, we present a method to construct multilocus models in the infinite island model of population structure (where deme size may be arbitrarily small). This method allows one to compute recursions on allele frequencies, and different types of genetic associations (including associations between different individuals from the same deme), and incorporates selection. Recursions can be simplified using quasi-equilibrium approximations; however, we show that quasi-equilibrium calculations for associations that are different from zero under neutrality must include a term that has not been previously considered. The method is illustrated using simple examples.
Eisenstein series for infinite-dimensional U-duality groups
NASA Astrophysics Data System (ADS)
Fleig, Philipp; Kleinschmidt, Axel
2012-06-01
We consider Eisenstein series appearing as coefficients of curvature corrections in the low-energy expansion of type II string theory four-graviton scattering amplitudes. We define these Eisenstein series over all groups in the E n series of string duality groups, and in particular for the infinite-dimensional Kac-Moody groups E 9, E 10 and E 11. We show that, remarkably, the so-called constant term of Kac-Moody-Eisenstein series contains only a finite number of terms for particular choices of a parameter appearing in the definition of the series. This resonates with the idea that the constant term of the Eisenstein series encodes perturbative string corrections in BPS-protected sectors allowing only a finite number of corrections. We underpin our findings with an extensive discussion of physical degeneration limits in D < 3 space-time dimensions.
Doubly infinite separation of quantum information and communication
NASA Astrophysics Data System (ADS)
Liu, Zi-Wen; Perry, Christopher; Zhu, Yechao; Koh, Dax Enshan; Aaronson, Scott
2016-01-01
We prove the existence of (one-way) communication tasks with a subconstant versus superconstant asymptotic gap, which we call "doubly infinite," between their quantum information and communication complexities. We do so by studying the exclusion game [C. Perry et al., Phys. Rev. Lett. 115, 030504 (2015), 10.1103/PhysRevLett.115.030504] for which there exist instances where the quantum information complexity tends to zero as the size of the input n increases. By showing that the quantum communication complexity of these games scales at least logarithmically in n , we obtain our result. We further show that the established lower bounds and gaps still hold even if we allow a small probability of error. However in this case, the n -qubit quantum message of the zero-error strategy can be compressed polynomially.
Infinite-noise criticality: Nonequilibrium phase transitions in fluctuating environments
NASA Astrophysics Data System (ADS)
Vojta, Thomas; Hoyos, Jose
We study the effects of time-varying environmental noise on nonequilibrium phase transitions in spreading and growth processes. Using the examples of the logistic evolution equation as well as the contact process, we show that such temporal disorder gives rise to a distinct type of critical points at which the effective noise amplitude diverges on long time scales. This leads to enormous density fluctuations characterized by an infinitely broad probability distribution at criticality. We develop a real-time renormalization-group theory that provides a general framework for the effects of temporal disorder on nonequilibrium processes. We also discuss how general this exotic critical behavior is, we illustrate the results by computer simulations, and we touch upon experimental applications of our theory. Supported by the NSF under Grant No. DMR-1205803, by Simons Foundation, by FAPESP under Grant No. 2013/09850-7, and by CNPq under Grant Nos. 590093/2011-8 and 305261/2012-6.
A General No-Cloning Theorem for an infinite Multiverse
NASA Astrophysics Data System (ADS)
Gauthier, Yvon
2013-10-01
In this paper, I formulate a general no-cloning theorem which covers the quantum-mechanical and the theoretical quantum information cases as well as the cosmological multiverse theory. However, the main argument is topological and does not involve the peculiar copier devices of the quantum-mechanical and information-theoretic approaches to the no-cloning thesis. It is shown that a combinatorial set-theoretic treatment of the mathematical and physical spacetime continuum in cosmological or quantum-mechanical terms forbids an infinite (countable or uncountable) number of exact copies of finite elements (states) in the uncountable multiverse cosmology. The historical background draws on ideas from Weyl to Conway and Kochen on the free will theorem in quantum mechanics.
Predictive optimized adaptive PSS in a single machine infinite bus.
Milla, Freddy; Duarte-Mermoud, Manuel A
2016-07-01
Power System Stabilizer (PSS) devices are responsible for providing a damping torque component to generators for reducing fluctuations in the system caused by small perturbations. A Predictive Optimized Adaptive PSS (POA-PSS) to improve the oscillations in a Single Machine Infinite Bus (SMIB) power system is discussed in this paper. POA-PSS provides the optimal design parameters for the classic PSS using an optimization predictive algorithm, which adapts to changes in the inputs of the system. This approach is part of small signal stability analysis, which uses equations in an incremental form around an operating point. Simulation studies on the SMIB power system illustrate that the proposed POA-PSS approach has better performance than the classical PSS. In addition, the effort in the control action of the POA-PSS is much less than that of other approaches considered for comparison.
Phases of the infinite U Hubbard model on square lattices.
Liu, Li; Yao, Hong; Berg, Erez; White, Steven R; Kivelson, Steven A
2012-03-23
We apply the density matrix renormalization group to study the phase diagram of the infinite U Hubbard model on 2- to 6-leg ladders. Where the results are largely insensitive to the ladder width, we consider the results representative of the 2D square lattice. We find a fully polarized ferromagnetic Fermi liquid phase when n, the density of electrons per site, is in the range 1>n≳0.800. For n=3/4 we find an unexpected insulating checkerboard phase with coexisting bond-density order with 4 sites per unit cell and block-spin antiferromagnetic order with 8 sites per unit cell. For 3/4>n, all ladders with width >2 have unpolarized ground states. PMID:22540606
LETTERS AND COMMENTS: Noninteracting fermions in infinite dimensions
NASA Astrophysics Data System (ADS)
Acharyya, Muktish
2010-11-01
Usually, we study the statistical behaviour of noninteracting fermions in finite (mainly two and three) dimensions. For a fixed number of fermions, the average energy per fermion is calculated in two and in three dimensions, and it becomes equal to 50% and 60% of the Fermi energy respectively. However, in higher dimensions this percentage increases as the dimensionality increases, and in infinite dimensions it becomes 100%. This is an interesting result, at least pedagogically, which implies that all fermions are moving with Fermi momentum. This result is not yet discussed in standard text books of quantum statistics. Here this fact is discussed and explained. I hope that this letter will be helpful for graduate students to study the behaviours of free fermions in generalized dimensionality.
Exploring percolative landscapes: Infinite cascades of geometric phase transitions
NASA Astrophysics Data System (ADS)
Timonin, P. N.; Chitov, Gennady Y.
2016-01-01
The evolution of many kinetic processes in 1+1 (space-time) dimensions results in 2 D directed percolative landscapes. The active phases of these models possess numerous hidden geometric orders characterized by various types of large-scale and/or coarse-grained percolative backbones that we define. For the patterns originated in the classical directed percolation (DP) and contact process we show from the Monte Carlo simulation data that these percolative backbones emerge at specific critical points as a result of continuous phase transitions. These geometric transitions belong to the DP universality class and their nonlocal order parameters are the capacities of corresponding backbones. The multitude of conceivable percolative backbones implies the existence of infinite cascades of such geometric transitions in the kinetic processes considered. We present simple arguments to support the conjecture that such cascades of transitions are a generic feature of percolation as well as of many other transitions with nonlocal order parameters.
Recurrent kernel machines: computing with infinite echo state networks.
Hermans, Michiel; Schrauwen, Benjamin
2012-01-01
Echo state networks (ESNs) are large, random recurrent neural networks with a single trained linear readout layer. Despite the untrained nature of the recurrent weights, they are capable of performing universal computations on temporal input data, which makes them interesting for both theoretical research and practical applications. The key to their success lies in the fact that the network computes a broad set of nonlinear, spatiotemporal mappings of the input data, on which linear regression or classification can easily be performed. One could consider the reservoir as a spatiotemporal kernel, in which the mapping to a high-dimensional space is computed explicitly. In this letter, we build on this idea and extend the concept of ESNs to infinite-sized recurrent neural networks, which can be considered recursive kernels that subsequently can be used to create recursive support vector machines. We present the theoretical framework, provide several practical examples of recursive kernels, and apply them to typical temporal tasks.
Broadband computation of the scattering coefficients of infinite arbitrary cylinders.
Blanchard, Cédric; Guizal, Brahim; Felbacq, Didier
2012-07-01
We employ a time-domain method to compute the near field on a contour enclosing infinitely long cylinders of arbitrary cross section and constitution. We therefore recover the cylindrical Hankel coefficients of the expansion of the field outside the circumscribed circle of the structure. The recovered coefficients enable the wideband analysis of complex systems, e.g., the determination of the radar cross section becomes straightforward. The prescription for constructing such a numerical tool is provided in great detail. The method is validated by computing the scattering coefficients for a homogeneous circular cylinder illuminated by a plane wave, a problem for which an analytical solution exists. Finally, some radiation properties of an optical antenna are examined by employing the proposed technique.
Solutions of evolution equations associated to infinite-dimensional Laplacian
NASA Astrophysics Data System (ADS)
Ouerdiane, Habib
2016-05-01
We study an evolution equation associated with the integer power of the Gross Laplacian ΔGp and a potential function V on an infinite-dimensional space. The initial condition is a generalized function. The main technique we use is the representation of the Gross Laplacian as a convolution operator. This representation enables us to apply the convolution calculus on a suitable distribution space to obtain the explicit solution of the perturbed evolution equation. Our results generalize those previously obtained by Hochberg [K. J. Hochberg, Ann. Probab. 6 (1978) 433.] in the one-dimensional case with V=0, as well as by Barhoumi-Kuo-Ouerdiane for the case p=1 (See Ref. [A. Barhoumi, H. H. Kuo and H. Ouerdiane, Soochow J. Math. 32 (2006) 113.]).
Variational optimization with infinite projected entangled-pair states
NASA Astrophysics Data System (ADS)
Corboz, Philippe
2016-07-01
We present a scheme to perform an iterative variational optimization with infinite projected entangled-pair states, a tensor network ansatz for a two-dimensional wave function in the thermodynamic limit, to compute the ground state of a local Hamiltonian. The method is based on a systematic summation of Hamiltonian contributions using the corner-transfer-matrix method. Benchmark results for challenging problems are presented, including the two-dimensional Heisenberg model, the Shastry-Sutherland model, and the t -J model, which show that the variational scheme yields considerably more accurate results than the previously best imaginary-time evolution algorithm, with a similar computational cost and with a faster convergence towards the ground state.
Persistence in nonautonomous predator-prey systems with infinite delays
NASA Astrophysics Data System (ADS)
Teng, Zhidong; Rehim, Mehbuba
2006-12-01
This paper studies the general nonautonomous predator-prey Lotka-Volterra systems with infinite delays. The sufficient and necessary conditions of integrable form on the permanence and persistence of species are established. A very interesting and important property of two-species predator-prey systems is discovered, that is, the permanence of species and the existence of a persistent solution are each other equivalent. Particularly, for the periodic system with delays, applying these results, the sufficient and necessary conditions on the permanence and the existence of positive periodic solutions are obtained. Some well-known results on the nondelayed periodic predator-prey Lotka-Volterra systems are strongly improved and extended to the delayed case.
NASA Astrophysics Data System (ADS)
Lin, T.; Ke, X.; Thesberg, M.; Schiffer, P.; Melko, R. G.; Gingras, M. J. P.
2014-12-01
Spin ice materials, such as Dy2Ti2O7 and Ho2Ti2O7 , are highly frustrated magnetic systems. Their low-temperature strongly correlated state can be mapped onto the proton disordered state of common water ice. As a result, spin ices display the same low-temperature residual Pauling entropy as water ice, at least in calorimetric experiments that are equilibrated over moderately long-time scales. It was found in a previous study [X. Ke et al., Phys. Rev. Lett. 99, 137203 (2007), 10.1103/PhysRevLett.99.137203] that, upon dilution of the magnetic rare-earth ions (Dy3 + and Ho3 +) by nonmagnetic yttrium (Y3 +) ions, the residual entropy depends nonmonotonically on the concentration of Y3 + ions. A quantitative description of the magnetic specific heat of site-diluted spin ice materials can be viewed as a further test aimed at validating the microscopic Hamiltonian description of these systems. In this work, we report results from Monte Carlo simulations of site-diluted microscopic dipolar spin ice models (DSIM) that account quantitatively for the experimental specific-heat measurements, and thus also for the residual entropy, as a function of dilution, for both Dy2 -xYxTi2O7 and Ho2 -xYxTi2O7 . The main features of the dilution physics displayed by the magnetic specific-heat data are quantitatively captured by the diluted DSIM up to 85% of the magnetic ions diluted (x =1.7 ). The previously reported departures in the residual entropy between Dy2 -xYxTi2O7 versus Ho2 -xYxTi2O7 , as well as with a site-dilution variant of Pauling's approximation, are thus rationalized through the site-diluted DSIM. We find for 90% (x =1.8 ) and 95% (x =1.9 ) of the magnetic ions diluted in Dy2 -xYxTi2O7 a significant discrepancy between the experimental and Monte Carlo specific-heat results. We discuss possible reasons for this disagreement.
A nanoliter microfluidic serial dilution bioreactor.
Gu, Guo-Yue; Lee, Yi-Wei; Chiang, Chih-Chung; Yang, Ya-Tang
2015-07-01
Bacterial culture is a basic technique in both fundamental and applied microbiology. The excessive reagent consumption and laborious maintenance of bulk bioreactors for microbial culture have prompted the development of miniaturized on-chip bioreactors. With the minimal choice of two compartments (N = 2) and discrete time, periodic dilution steps, we realize a microfluidic bioreactor that mimics macroscopic serial dilution transfer culture. This device supports automated, long-term microbial cultures with a nanoliter-scale working volume and real-time monitoring of microbial populations at single-cell resolution. Because of the high surface-to-volume ratio, the device also operates as an effective biofilm-flow reactor to support cogrowth of planktonic and biofilm populations. We expect that such devices will open opportunities in many fields of microbiology.
Kinetic model for dilute traffic flow
NASA Astrophysics Data System (ADS)
Balouchi, Ashkan; Browne, Dana A.
The flow of traffic represents a many-particle non-equilibrium problem with important practical consequences. Traffic behavior has been studied using a variety of approaches, including fluid dynamics models, Boltzmann equation, and recently cellular automata (CA). The CA model for traffic flow that Nagel and Schreckenberg (NS) introduced can successfully mimic many of the known features of the traffic flow. We show that in the dilute limit of the NS model, where vehicles exhibit free flow, cars show significant nearest neighbor correlation primarily via a short-range repulsion. introduce an approximate analytic model to describe this dilute limit. We show that the distribution of the distance between consecutive vehicles obeys a drift-diffusion equation. We compared this model with direct simulations. The steady state solution and relaxation of this model agrees well with direct simulations. We explore how this model breaks down as the transition to jams occurs.
Defect formation and carrier doping in epitaxial films of the infinite layer compound
Feenstra, R.; Pennycook, S.J.; Chisholm, M.F.
1996-02-01
The correlation between defect formation and carrier doping in epitaxial films of the infinite layer compound SrCuO{sub 2} has been studied via molecular beam epitaxy controlled layer-by-layer growth experiments, chemically resolved scanning transmission electron microscopy, scanning tunneling microscopy, x-ray diffraction, electrical transport measurements, and post-growth oxidation-reduction annealing. Based on the complementary information provided by these experiments, it is concluded that the carrier doping is dominated by the formation of an electron-doped, Sr and O deficient matrix under mildly oxidizing growth conditions. Hole-doping is induced by extended defects containing excess Sr atoms and may lead to superconductivity after high-temperature oxidation.
Observation of a relaxed plasma state in a quasi-infinite cylinder.
Gray, T; Brown, M R; Dandurand, D
2013-02-22
A helical relaxed plasma state is observed in a long cylindrical volume. The cylinder is long enough so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at v ≥ 50 km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. The relaxed state is rapidly attained in 1-2 axial Alfvén times after initiation of the plasma. Magnetic data are favorably compared with an analytical model. Magnetic data exhibit broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement with the minimum energy eigenstate of [Symbol: see text] × B = λB.
Observation of a Relaxed Plasma State in a Quasi-Infinite Cylinder
NASA Astrophysics Data System (ADS)
Gray, T.; Brown, M. R.; Dandurand, D.
2013-02-01
A helical relaxed plasma state is observed in a long cylindrical volume. The cylinder is long enough so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at v≥50km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. The relaxed state is rapidly attained in 1-2 axial Alfvén times after initiation of the plasma. Magnetic data are favorably compared with an analytical model. Magnetic data exhibit broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement with the minimum energy eigenstate of ∇×B=λB.
Infinite capacity multi-server queue with second optional service channel
NASA Astrophysics Data System (ADS)
Ke, Jau-Chuan; Wu, Chia-Huang; Pearn, Wen Lea
2013-02-01
This paper deals with an infinite-capacity multi-server queueing system with a second optional service (SOS) channel. The inter-arrival times of arriving customers, the service times of the first essential service (FES) and the SOS channel are all exponentially distributed. A customer may leave the system after the FES channel with probability (1-θ), or at the completion of the FES may immediately require a SOS with probability θ (0 <= θ <= 1). The formulae for computing the rate matrix and stationary probabilities are derived by means of a matrix analytical approach. A cost model is developed to determine the optimal values of the number of servers and the two service rates, simultaneously, at the minimal total expected cost per unit time. Quasi-Newton method are employed to deal with the optimization problem. Under optimal operating conditions, numerical results are provided in which several system performance measures are calculated based on assumed numerical values of the system parameters.
Dilution physics modeling: Dissolution/precipitation chemistry
Onishi, Y.; Reid, H.C.; Trent, D.S.
1995-09-01
This report documents progress made to date on integrating dilution/precipitation chemistry and new physical models into the TEMPEST thermal-hydraulics computer code. Implementation of dissolution/precipitation chemistry models is necessary for predicting nonhomogeneous, time-dependent, physical/chemical behavior of tank wastes with and without a variety of possible engineered remediation and mitigation activities. Such behavior includes chemical reactions, gas retention, solids resuspension, solids dissolution and generation, solids settling/rising, and convective motion of physical and chemical species. Thus this model development is important from the standpoint of predicting the consequences of various engineered activities, such as mitigation by dilution, retrieval, or pretreatment, that can affect safe operations. The integration of a dissolution/precipitation chemistry module allows the various phase species concentrations to enter into the physical calculations that affect the TEMPEST hydrodynamic flow calculations. The yield strength model of non-Newtonian sludge correlates yield to a power function of solids concentration. Likewise, shear stress is concentration-dependent, and the dissolution/precipitation chemistry calculations develop the species concentration evolution that produces fluid flow resistance changes. Dilution of waste with pure water, molar concentrations of sodium hydroxide, and other chemical streams can be analyzed for the reactive species changes and hydrodynamic flow characteristics.
THE ANISOTROPIC TRANSPORT EFFECTS ON DILUTE PLASMAS
Devlen, Ebru
2011-04-20
We examine the linear stability analysis of a hot, dilute, and differentially rotating plasma by considering anisotropic transport effects. In dilute plasmas, the ion Larmor radius is small compared with its collisional mean free path. In this case, the transport of heat and momentum along the magnetic field lines becomes important. This paper presents a novel linear instability that may be more powerful and greater than ideal magnetothermal instability and ideal magnetorotational instability in the dilute astrophysical plasmas. This type of plasma is believed to be found in the intracluster medium (ICM) of galaxy clusters and radiatively ineffective accretion flows around black holes. We derive the dispersion relation of this instability and obtain the instability condition. There is at least one unstable mode that is independent of the temperature gradient direction for a helical magnetic field geometry. This novel instability is driven by the gyroviscosity coupled with differential rotation. Therefore, we call it gyroviscous-modified magnetorotational instability (GvMRI). We examine how the instability depends on signs of the temperature gradient and the gyroviscosity and also on the magnitude of the thermal frequency and on the values of the pitch angle. We provide a detailed physical interpretation of the obtained results. The GvMRI is applicable not only to the accretion flows and ICM but also to the transition region between cool dense gas and the hot low-density plasma in stellar coronae, accretion disks, and the multiphase interstellar medium because it is independent of the temperature gradient direction.
A piezoelectric-based infinite stiffness generation method for strain-type load sensors
NASA Astrophysics Data System (ADS)
Zhang, Shuwen; Shao, Shubao; Chen, Jie; Xu, Minglong
2015-11-01
Under certain application conditions like nanoindentation technology and the mechanical property measurement of soft materials, the elastic deformation of strain-type load sensors affects their displacement measurement accuracy. In this work, a piezoelectric-based infinite stiffness generation method for strain-type load sensors that compensates for this elastic deformation is presented. The piezoelectric material-based deformation compensation method is proposed. An Hottinger Baldwin Messtechnik GmbH (HBM) Z30A/50N load sensor acts as the foundation of the method presented in this work. The piezoelectric stack is selected based on its size, maximum deformation value, blocking force and stiffness. Then, a clamping and fixing structure is designed to integrate the HBM sensor with the piezoelectric stack. The clamping and fixing structure, piezoelectric stack and HBM load sensor comprise the sensing part of the enhanced load sensor. The load-deformation curve and the voltage-deformation curve of the enhanced load sensor are then investigated experimentally. Because a hysteresis effect exists in the piezoelectric structure, the relationship between the control signal and the deformation value of the piezoelectric material is nonlinear. The hysteresis characteristic in a quasi-static condition is studied and fitted using a quadratic polynomial, and its coefficients are analyzed to enable control signal prediction. Applied arithmetic based on current theory and the fitted data is developed to predict the control signal. Finally, the experimental effects of the proposed method are presented. It is shown that when a quasi-static load is exerted on this enhanced strain-type load sensor, the deformation is reduced and the equivalent stiffness appears to be almost infinite.
Technology Transfer Automated Retrieval System (TEKTRAN)
Body composition indicators provide a better guidance for growth and nutritional status of the infants. This study was designed to (1) measure the body composition of the Sri Lankan infants using a reference method, the 18*O dilution method; (2) calculate the body fat content of the infants using pu...
Effects of dilution on elastohydrodynamic coating flow of an anti-HIV microbicide vehicle
NASA Astrophysics Data System (ADS)
Szeri, Andrew; Park, Su Chan; Tasoglu, Savas; Katz, David F.
2009-11-01
Elastohydrodynamic lubrication over soft substrates characterizes the drug delivery of anti-HIV topical microbicides carried in gel vehicles. These gels are under development to prevent HIV transmission into vulnerable vaginal mucosa during intercourse. Their effectiveness depends on completeness and durability of coating, as well as on the active ingredients. Here we investigate the influence of dilution by vaginal fluid on the coating flows that serve to protect the user. The effects of dilution by vaginal fluid simulant are assessed through rheological experiments at variable dilution of the gel vehicle. This involves determination of the way parameters in a Carreau model of a shear-thinning gel are modified by dilution. The changes in coating are determined from a computational model, based on dilution rheology measured in the laboratory. The elastohydrodynamic lubrication model of Szeri, et al. Physics of Fluids (2008) is supplemented with a convective-diffusive transport equation to handle dilution, and solved using a multi-step scheme in a moving domain.
Helium 3/Helium 4 dilution cryocooler for space
NASA Technical Reports Server (NTRS)
Hendricks, John B.; Dingus, Michael L.
1991-01-01
Prototype dilution cryocoolers based on dilution refrigeration and adiabatic demagnetization refrigeration (ADR) cycles were designed, constructed, and tested. Although devices the devices did not operate as fully functional dilution cryocoolers, important information was gathered. The porous metal phase separator was demonstrated to operate in the -1-g configuration; this phase separation is the critical element in the He-3 circulation dilution cryocooler. Improvements in instrumentation needed for additional tests and development were identified.
Effect of modularity on the Glauber dynamics of the dilute spin glass model
NASA Astrophysics Data System (ADS)
Park, Jeong-Man
2014-11-01
We study the Glauber dynamics of the dilute, infinite-ranged spin glass model, the so-called dilute Sherrington-Kirkpatrick (dSK) model. The dSK model has sparse couplings and can be classified by the modularity ( M) of the coupling matrix. We investigate the effect of the modularity on the relaxation dynamics starting from a random initial state. By using the Glauber dynamics and the replica method, we derive the relaxation dynamics equations for the magnetization ( m) and the energy per spin ( r), in addition to the equation for the spin glass order parameter ( q αβ ). In the replica symmetric (RS) analysis, we find that there are two solutions for the RS spin glass order parameter ( q): q = 0which is stable for r < 1/2 and q = (-1+4 r 2)/(32 r 4) which is stable for r > 1/2 in the non-modular system and q = 0 which is stable for r < 1/ and q = (-1+8 r 2)/(128 r 4) which is stable for r > 1/ in the completely modular system. By substituting the proper q values into the equations for r, we find that the relaxation dynamics of r depends on the modularity, M. These results suggest that, in the context of evolutionary theory, the modularity may emerge spontaneously in the point-mutation-only framework (Glauber dynamics) under a changing environment.
NASA Astrophysics Data System (ADS)
Nastac, Laurentiu
1998-09-01
Existing analytical models for calculating solute redistribution during the initial transient (unsteady) unidirectional solidification with an axially moving boundary of binary dilute alloys were reviewed. The analytical solution obtained by Smith, Tiller, Rutter (STR) [Can. J. Phys. 33 (1955) 723] for semi-infinite domains was derived independently in this work. In obtaining the solution, STR used Laplace transform technique. In this work, it was rigorously proved by using Laplace transform, nondimensional analysis, and by eliminating the advection term in Eq. (1), that the analytical solution found by STR is indeed "exact" and "unique" under the stated assumptions. A thorough comparison between the exact solution and some approximate solutions is provided for partition distribution coefficients smaller and larger than one. Transient and quasi-steady-state results obtained with the exact analytical solution for segregation profiles in the liquid and at the solid/liquid interface, liquid concentration gradient at the solid/liquid interface, and solutal boundary layer are discussed in details. The size of the initial transient region is calculated. The exact solution is then applied to investigate based on thermodynamic arguments the instability of the solid/liquid interface during the initial solidification regime of dilute alloys.
21 CFR 172.710 - Adjuvants for pesticide use dilutions.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Adjuvants for pesticide use dilutions. 172.710... HUMAN CONSUMPTION Other Specific Usage Additives § 172.710 Adjuvants for pesticide use dilutions. The following surfactants and related adjuvants may be safely added to pesticide use dilutions by a grower...
21 CFR 172.710 - Adjuvants for pesticide use dilutions.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Adjuvants for pesticide use dilutions. 172.710... HUMAN CONSUMPTION Other Specific Usage Additives § 172.710 Adjuvants for pesticide use dilutions. The following surfactants and related adjuvants may be safely added to pesticide use dilutions by a grower...
Maxwell-Higgs self-dual solitons on an infinite cylinder
NASA Astrophysics Data System (ADS)
Casana, Rodolfo; Sourrouille, Lucas
2015-07-01
We have studied the Maxwell-Higgs model on the surface of an infinite cylinder. In particular, we show that this model supports self-dual topological soliton solutions on the infinite tube. Finally, the Bogomol’nyi-type equations are studied from theoretical and numerical point of view.
ERIC Educational Resources Information Center
Tsamir, Pessia
1999-01-01
Describes a course in Cantorian Set Theory relating to prospective secondary mathematics teachers' tendencies to overgeneralize from finite to infinite sets. Indicates that when comparing the number of elements in infinite sets, teachers who took the course were more successful and more consistent in their use of single method than those who…
Monreal, Marisa J; Seaman, Lani A; Goff, George S; Michalczyk, Ryszard; Morris, David E; Scott, Brian L; Kiplinger, Jaqueline L
2016-03-01
Two organometallic 1D infinite coordination polymers and two organometallic monometallic complexes of thorium diazide have been synthesized and characterized. Steric control of these self-assembled arrays, which are dense in thorium and nitrogen, has also been demonstrated: infinite chains can be circumvented by using steric bulk either at the metallocene or with a donor ligand in the wedge. PMID:26865502
Masiero, Federica
2007-05-15
Semilinear elliptic partial differential equations are solved in a mild sense in an infinite-dimensional Hilbert space. These results are applied to a stochastic optimal control problem with infinite horizon. Applications to controlled stochastic heat and wave equations are given.
Confusing Aspects in the Calculation of the Electrostatic Potential of an Infinite Line of Charge
ERIC Educational Resources Information Center
Jimenez, J. L.; Campos, I.; Roa-Neri, J. A. E.
2012-01-01
In this work we discuss the trick of eliminating infinite potential of reference arguing that it corresponds to a constant of integration, in the problem of determining the electrostatic potential of an infinite line of charge with uniform density, and show how the problem must be tackled properly. The usual procedure is confusing for most…
A conformal truncation framework for infinite-volume dynamics
NASA Astrophysics Data System (ADS)
Katz, Emanuel; Khandker, Zuhair U.; Walters, Matthew T.
2016-07-01
We present a new framework for studying conformal field theories deformed by one or more relevant operators. The original CFT is described in infinite volume using a basis of states with definite momentum, P , and conformal Casimir, C. The relevant deformation is then considered using lightcone quantization, with the resulting Hamiltonian expressed in terms of this CFT basis. Truncating to states with C ≤ C_{max } , one can numerically find the resulting spectrum, as well as other dynamical quantities, such as spectral densities of operators. This method requires the introduction of an appropriate regulator, which can be chosen to preserve the conformal structure of the basis. We check this framework in three dimensions for various perturbative deformations of a free scalar CFT, and for the case of a free O( N ) CFT deformed by a mass term and a non-perturbative quartic interaction at large- N . In all cases, the truncation scheme correctly reproduces known analytic results. We also discuss a general procedure for generating a basis of Casimir eigenstates for a free CFT in any number of dimensions.
Communication Tasks with Infinite Quantum-Classical Separation.
Perry, Christopher; Jain, Rahul; Oppenheim, Jonathan
2015-07-17
Quantum resources can be more powerful than classical resources-a quantum computer can solve certain problems exponentially faster than a classical computer, and computing a function of two parties' inputs can be done with exponentially less communication with quantum messages than with classical ones. Here we consider a task between two players, Alice and Bob where quantum resources are infinitely more powerful than their classical counterpart. Alice is given a string of length n, and Bob's task is to exclude certain combinations of bits that Alice might have. If Alice must send classical messages, then she must reveal nearly n bits of information to Bob, but if she is allowed to send quantum bits, the amount of information she must reveal goes to zero with increasing n. Next, we consider a version of the task where the parties may have access to entanglement. With this assistance, Alice only needs to send a constant number of bits, while without entanglement, the number of bits Alice must send grows linearly with n. The task is related to the Pusey-Barrett-Rudolph theorem which arises in the context of the foundations of quantum theory. PMID:26230777
Oscillating laminar electrokinetic flow in infinitely extended circular microchannels.
Bhattacharyya, A; Masliyah, J H; Yang, J
2003-05-01
This article addresses the problem of oscillating laminar electrokinetic liquid flow in an infinitely extended circular microchannel. Based on the Debye-Huckel approximation for low surface potential at the channel wall, a complex variable approach is used to obtain an analytical solution for the flow. The complex counterparts of the flow rate and the current are linearly dependent on the pressure gradient and the external electric field. This property is used to show that Onsager's principle of reciprocity continues to be valid (involving the complex quantities) for the stated problem. During oscillating pressure-driven flow, the electroviscous effect for a given value of the normalized reciprocal electrical double-layer (EDL) thickness is observed to attain a maximum at a certain normalized frequency. In general, an increasing normalized frequency results in a reduction of EDL effects, leading to (i). a volumetric flow rate in the case of streaming potential approaching that predicted by the theory without EDL effects, and (ii). a reduction in the volumetric flow rate in the case of electroosmosis. PMID:12725819
Infinite hidden conditional random fields for human behavior analysis.
Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja
2013-01-01
Hidden conditional random fields (HCRFs) are discriminative latent variable models that have been shown to successfully learn the hidden structure of a given classification problem (provided an appropriate validation of the number of hidden states). In this brief, we present the infinite HCRF (iHCRF), which is a nonparametric model based on hierarchical Dirichlet processes and is capable of automatically learning the optimal number of hidden states for a classification task. We show how we learn the model hyperparameters with an effective Markov-chain Monte Carlo sampling technique, and we explain the process that underlines our iHCRF model with the Restaurant Franchise Rating Agencies analogy. We show that the iHCRF is able to converge to a correct number of represented hidden states, and outperforms the best finite HCRFs--chosen via cross-validation--for the difficult tasks of recognizing instances of agreement, disagreement, and pain. Moreover, the iHCRF manages to achieve this performance in significantly less total training, validation, and testing time. PMID:24808217
Partition Theory for Periodic and Semi-Infinite Systems
NASA Astrophysics Data System (ADS)
Niffenegger, Kelsie; Wasserman, Adam
Standard approximations to the exchange-correlation (XC) functional of Kohn-Sham Density-Functional Theory are insufficiently accurate to describe charge transfer at metal-atom interfaces and other systems requiring proper treatment of fractional electron charges. The root of the problem is connected to the lack of derivative discontinuities in the approximate XC functionals at integer numbers of electrons. Partition Theory (PT) is a promising, formally exact method to correct this issue. We study the simplest model for an atom adsorbed at a metal surface: A one-dimensional step potential separated a fixed distance from an attractive well that admits only one bound state when isolated. The semi-infinite metal is populated with non-interacting electrons up to the Fermi energy. We derive the PT-equations for this problem and indicate how the associated partition potential can be calculated. PT is also a promising method for improving the computational scaling of other large and/or periodic systems. We study the partition potential for periodic 1-D chains of identical attractive wells and comment on the uniqueness of the partition potential when going from finite to periodic systems.
Communication Tasks with Infinite Quantum-Classical Separation.
Perry, Christopher; Jain, Rahul; Oppenheim, Jonathan
2015-07-17
Quantum resources can be more powerful than classical resources-a quantum computer can solve certain problems exponentially faster than a classical computer, and computing a function of two parties' inputs can be done with exponentially less communication with quantum messages than with classical ones. Here we consider a task between two players, Alice and Bob where quantum resources are infinitely more powerful than their classical counterpart. Alice is given a string of length n, and Bob's task is to exclude certain combinations of bits that Alice might have. If Alice must send classical messages, then she must reveal nearly n bits of information to Bob, but if she is allowed to send quantum bits, the amount of information she must reveal goes to zero with increasing n. Next, we consider a version of the task where the parties may have access to entanglement. With this assistance, Alice only needs to send a constant number of bits, while without entanglement, the number of bits Alice must send grows linearly with n. The task is related to the Pusey-Barrett-Rudolph theorem which arises in the context of the foundations of quantum theory.
Spectral Methods Using Rational Basis Functions on an Infinite Interval
NASA Astrophysics Data System (ADS)
Boyd, John P.
1987-03-01
By using the map y = L cot( t) where L is a constant, differential equations on the interval yɛ [- ∞, ∞] can be transformed into tɛ [0, π] and solved by an ordinary Fourier series. In this article, earlier work by Grosch and Orszag ( J. Comput. Phys.25, 273 (1977)), Cain, Ferziger, and Reynolds ( J. Comput. Phys.56, 272 (1984)), and Boyd ( J. Comput. Phys.25, 43 (1982); 57, 454 (1985); SIAM J. Numer. Anal. (1987)) is extended in several ways. First, the series of orthogonal rational functions converge on the exterior of bipolar coordinate surfaces in the complex y-plane. Second, Galerkin's method will convert differential equations with polynomial or rational coefficients into banded matrix problems. Third, with orthogonal rational functions it is possible to obtain exponential convergence even for u( y) that asymptote to a constant although this behavior would wreck alternatives such as Hermite or sinc expansions. Fourth, boundary conditions are usually "natural" rather than "essential" in the sense that the singularities of the differential equation will force the numerical solution to have the correct behavior at infinity even if no constraints are imposed on the basis functions. Fifth, mapping a finite interval to an infinite one and then applying the rational Chebyshev functions gives an exponentially convergent method for functions with bounded endpoint singularities. These concepts are illustrated by five numerical examples.
Scattering by infinitely rising one-dimensional potentials
NASA Astrophysics Data System (ADS)
Ferreira, E. M.; Sesma, J.
2015-12-01
Infinitely rising one-dimensional potentials constitute impenetrable barriers which reflect totally any incident wave. However, the scattering by such kind of potentials is not structureless: resonances may occur for certain values of the energy. Here we consider the problem of scattering by the members of a family of potentials Va(x) = - sgn(x) | x | a, where sgn represents the sign function and a is a positive rational number. The scattering function and the phase shifts are obtained from global solutions of the Schrödinger equation. For the determination of the Gamow states, associated to resonances, we exploit their close relation with the eigenvalues of the PT-symmetric Hamiltonians with potentials VaPT(x) = - i sgn(x) | x | a. Calculation of the time delay in the scattering at real energies is used to characterize the resonances. As an additional result, the breakdown of the PT-symmetry of the family of potentials VaPT for a < 3 may be conjectured.
Semiclassical limits of quantum partition functions on infinite graphs
Güneysu, Batu
2015-02-15
We prove that if H denotes the operator corresponding to the canonical Dirichlet form on a possibly locally infinite weighted graph (X, b, m), and if v : X → ℝ is such that H + v/ħ is well-defined as a form sum for all ħ > 0, then the quantum partition function tr(e{sup −βħ(H+v/ħ)}) converges to ∑{sub x∈X}e{sup −βv(x)} as ħ → 0 +, for all β > 0, regardless of the fact whether e{sup −βv} is a priori summable or not. This fact can be interpreted as a semiclassical limit, and it allows geometric Weyl-type convergence results. We also prove natural generalizations of this semiclassical limit to a large class of covariant Schrödinger operators that act on sections in Hermitian vector bundle over (X, m, b), a result that particularly applies to magnetic Schrödinger operators that are defined on (X, m, b)
A simple extrapolation of thermodynamic perturbation theory to infinite order
Ghobadi, Ahmadreza F.; Elliott, J. Richard
2015-09-21
Recent analyses of the third and fourth order perturbation contributions to the equations of state for square well spheres and Lennard-Jones chains show trends that persist across orders and molecular models. In particular, the ratio between orders (e.g., A{sub 3}/A{sub 2}, where A{sub i} is the ith order perturbation contribution) exhibits a peak when plotted with respect to density. The trend resembles a Gaussian curve with the peak near the critical density. This observation can form the basis for a simple recursion and extrapolation from the highest available order to infinite order. The resulting extrapolation is analytic and therefore cannot fully characterize the critical region, but it remarkably improves accuracy, especially for the binodal curve. Whereas a second order theory is typically accurate for the binodal at temperatures within 90% of the critical temperature, the extrapolated result is accurate to within 99% of the critical temperature. In addition to square well spheres and Lennard-Jones chains, we demonstrate how the method can be applied semi-empirically to the Perturbed Chain - Statistical Associating Fluid Theory (PC-SAFT)
Causal field theory with an infinite speed of sound
Afshordi, Niayesh; Chung, Daniel J. H.; Geshnizjani, Ghazal
2007-04-15
We introduce a model of scalar field dark energy, Cuscuton, which can be realized as the incompressible (or infinite speed of sound) limit of a scalar field theory with a noncanonical kinetic term (or k-essence). Even though perturbations of Cuscuton propagate superluminally, we show that they have a locally degenerate phase space volume (or zero entropy), implying that they cannot carry any microscopic information, and thus the theory is causal. Even coupling to ordinary scalar fields cannot lead to superluminal signal propagation. Furthermore, we show that the family of constant field hypersurfaces is the family of constant mean curvature hypersurfaces, which are the analogs of soap films (or soap bubbles) in Euclidian space. This enables us to find the most general solution in 1+1 dimensions, whose properties motivate conjectures for global degeneracy of the phase space in higher dimensions. Finally, we show that the Cuscuton action can model the continuum limit of the evolution of a field with discrete degrees of freedom and argue why it is protected against quantum corrections at low energies. While this paper mainly focuses on interesting features of Cuscuton in a Minkowski space-time, a companion paper examines cosmology with Cuscuton dark energy.
Wang, Yan Jason; Yang, Bo; Lipsky, Eric M; Robinson, Allen L; Zhang, K Max
2013-01-15
Experimental results from laboratory emission testing have indicated that particulate emission measurements are sensitive to the dilution process of exhaust using fabricated dilution systems. In this paper, we first categorize the dilution parameters into two groups: (1) aerodynamics (e.g., mixing types, mixing enhancers, dilution ratios, residence time); and (2) mixture properties (e.g., temperature, relative humidity, particle size distributions of both raw exhaust and dilution gas). Then we employ the Comprehensive Turbulent Aerosol Dynamics and Gas Chemistry (CTAG) model to investigate the effects of those parameters on a set of particulate emission measurements comparing two dilution tunnels, i.e., a T-mixing lab dilution tunnel and a portable field dilution tunnel with a type of coaxial mixing. The turbulent flow fields and aerosol dynamics of particles are simulated inside two dilution tunnels. Particle size distributions under various dilution conditions predicted by CTAG are evaluated against the experimental data. It is found that in the area adjacent to the injection of exhaust, turbulence plays a crucial role in mixing the exhaust with the dilution air, and the strength of nucleation dominates the level of particle number concentrations. Further downstream, nucleation terminates and the growth of particles by condensation and coagulation continues. Sensitivity studies reveal that a potential unifying parameter for aerodynamics, i.e., the dilution rate of exhaust, plays an important role in new particle formation. The T-mixing lab tunnel tends to favor the nucleation due to a larger dilution rate of the exhaust than the coaxial mixing field tunnel. Our study indicates that numerical simulation tools can be potentially utilized to develop strategies to reduce the uncertainties associated with dilution samplings of emission sources.
NASA Astrophysics Data System (ADS)
Kimchi, Itamar; Analytis, James G.; Vishwanath, Ashvin
2014-11-01
Motivated by the recent synthesis of two insulating Li2IrO3 polymorphs, where Ir4 + Seff=1 /2 moments form 3D ("harmonic") honeycomb structures with threefold coordination, we study magnetic Hamiltonians on the resulting β -Li2IrO3 hyperhoneycomb lattice and γ -Li2IrO3 stripyhoneycomb lattice. Experimentally measured magnetic susceptibilities suggest that Kitaev interactions, predicted for the ideal 90∘ Ir-O-Ir bonds, are sizable in these materials. We first consider pure Kitaev interactions, which lead to an exactly soluble 3D quantum spin liquid (QSL) with emergent Majorana fermions and Z2 flux loops. Unlike 2D QSLs, the 3D QSL is stable to finite temperature, with Tc≈|K | /100 . On including Heisenberg couplings, exact solubility is lost. However, by noting that the shortest closed loop ℓ is relatively large in these structures, we construct an ℓ →∞ approximation by defining the model on the Bethe lattice. The phase diagram of the Kitaev-Heisenberg model on this lattice is obtained directly in the thermodynamic limit, using tensor network states and the infinite-system time-evolving-block-decimation (iTEBD) algorithm. Both magnetically ordered and gapped QSL phases are found, the latter being identified by an entanglement fingerprint.
Hoover, Jill R.; Storkel, Holly L.; Rice, Mabel L.
2011-01-01
The effect of neighborhood density on optional infinitives was evaluated for typically developing (TD) children and children with Specific Language Impairment (SLI). Forty children, 20 in each group, completed two production tasks that assessed third person singular production. Half of the sentences in each task presented a dense verb, and half presented a sparse verb. Children’s third person singular accuracy was compared across dense and sparse verbs. Results showed that the TD group was significantly less likely to use optional infinitives with dense, rather than sparse verbs. In contrast, the distribution of optional infinitives for the SLI group was independent of verb neighborhood density. Follow-up analyses showed that the lack of neighborhood density effect for the SLI group could not be attributed to heterogeneous neighborhood density effects or floor effects. Results were interpreted within the Optional Infinitive/Extended Optional Infinitive accounts for typical language development and SLI for English speaking children. PMID:22123500
Solubility of solutes in compressed gases: Dilute solution theory
Wang, X.; Tavlarides, L.L. . Dept. of Chemical Engineering)
1994-03-01
A dilute solution theory is developed for describing the thermodynamic behavior of a compressed gaseous dilute solution. The considerations follow generally accepted statistical treatments for describing dilute liquid solutions. The theory is self-consistent with the ideal gas law for dilute gases and with Henry's law for dilute liquid (or solid) solutions. Further, it provides a simple linear relationship which represents well the solubility behavior of a heavy solute (solid or liquid) in a gaseous solvent over relatively wide density regions of the solvent (i.e., 0 [le] [rho] [le] 2.0/V[sub c]).
Magnetopolaron effect in diluted semimagnetic semiconductors
NASA Astrophysics Data System (ADS)
Tarasov, Georgiy G.; Mazur, Yuri I.; Rakitin, Andrey S.; Lavoric, S. R.; Tomm, Jens W.; Hoerstel, W.
1997-08-01
Phonon-assisted self-trapping of free carrier is considered in diluted semimagnetics. It is shown that the binding energy of free magnetic polaron can be substantially larger when the 'spin-phonon' coupling is taken into account. For the particular case of 'soft' lattice dynamics the region of stability for hole-induced polaron can be promoted to the temperature of tenths of degrees and magnetic field of a few Tesla. The possible hybridized excitations with the partition of free magnetic polaron are discussed in semimagnetic semiconductors.
Steadiness in Dilute Pyroclastic Density Currents
NASA Astrophysics Data System (ADS)
Andrews, B. J.
2015-12-01
Pyroclastic density currents (PDCs) are often unsteady, as evidenced by direct observations of dilute lobes or jets emerging from the fronts of larger currents and by deposits that indicate transient transport and depositional regimes. We used scaled experiments to investigate unsteadiness in dilute PDCs. The experimental currents were run in an 8.5x6.1x2.6 m tank and comprised heated or ambient temperature 20-μm talc powder turbulently suspended in air. Experiments were scaled such that densimetric and thermal Richardson numbers, Froude number, and particle Stokes and settling numbers were dynamically similar to natural dilute PDCs. Although the experiment Reynolds numbers are substantially lower than those of natural PDCs, the experiments are fully turbulent. Experiments were observed with video and high-speed cameras and high-frequency thermocouples. Currents were generated with total eruption durations of 100 s. Unsteadiness in source conditions was produced by interrupting supply for intervals, t, with durations of 1, 2.5, 5, and 10 s in the experimental runs at 35 and 70 s. When t<2.5 s, the currents are indistinguishable from currents with steady supply. In runs with t=2.5-5 s, the individual pulses comprising each current are readily apparent near the source, but decay with distance downstream until the currents appear as single (e.g. steady) flows. In experiments with t=10 s, the 3 pulses comprising each run never merge and the currents remain unsteady. Comparison with the integral turbulent timescale, τ, and current velocity, U, show that unsteadiness is persistent when t>3<τ but currents are steady when t<τ. In currents with 3τ>t>τ, unsteadiness decays such that at a distance of ~4Ut, the currents are again steady. Applied to natural dilute PDCs, our results suggest that currents and their resulting deposits, will only show evidence of unsteadiness if they are disrupted for many seconds and those breaks may "heal" over distances of 100s of meters.
Diluted Magnetic Iv-Vi Compounds
NASA Astrophysics Data System (ADS)
Bauer, G.; Pascher, H.
The following sections are included: * INTRODUCTION * MAGNETIC PROPERTIES * Susceptibility * High Field Magnetization * Spin Glass Phase * Free Carrier Induced Ferromagnetism * Magnetic Properties of Layered IV-VI Diluted Magnetic Semiconductors * CALCULATION OF LANDAU STATES: MEAN FIELD THEORY FOR IV-VI COMPOUNDS * MAGNETOTRANSPORT * OPTICAL INTERBAND TRANSITIONS * Photoluminescence Without Magnetic Field * Magnetooptical Interband Transitions * COHERENT RAMAN SCATTERING * Theory * Classical approach * Nonlinear susceptibility in semiconductors * Experimental Results and Discussion * Results: Pb1-xMnxTe * Results: Pb1-xEuxSe * Effective Electron and Hole g factors * FAR INFRARED SPECTROSCOPY * COMPARISON EXPERIMENT - MOLECULAR FIELD THEORY * Band and Exchange Parameters * Selection Rules * CONCLUSION * ACKNOWLEDGEMENTS * REFERENCES
Seo, Jeong Il; Shin, Hyun Dong; Kim, Nam Il
2008-05-15
The effects of fuel dilution with nitrogen on the propagation of tribrachial flames were studied experimentally using a multislot burner, which can stabilize lifted flames at low concentration gradients. Three fuel dilutions with nitrogen (N{sub 2} 0%, 25%, and 50% dilution) were employed. The lift-off height and OH-radical content of the flames were measured using an intensified CCD camera and an OH-PLIF scheme. Regardless of the fuel dilution mole fractions, the lift-off height of the tribrachial flames exhibited U-shaped trends with a minimal value during the increase of the concentration gradients. This implies that the propagation velocity is maximized at a specific concentration gradient regardless of the fuel dilution. Overall, the propagation velocity of the tribrachial flame was reduced by the fuel dilution, and the fuel dilution weakly affected the generation of the diffusion flame. The OH radicals in the diffusion branch became prominently active at the critical concentration gradient and these phenomena were more clearly detected at higher fuel dilution mole fractions. The decrease of the three modes of the OH radicals in a streamwise direction is discussed regarding the relation of the diffusion branch to the propagation velocity of the tribrachial flames. It is suggested that the effect of the diffusion branch on the propagation velocity of tribrachial flames needs to be reconsidered, especially when the concentration gradient is small. (author)
The Effect of Dilution on the Structure of Microbial Communities
NASA Technical Reports Server (NTRS)
Mills, Aaron L.
2000-01-01
To determine how dilution of microbial communities affects the diversity of the diluted assemblage a series of numerical simulations were conducted that determined the theoretical change in diversity, richness, and evenness of the community with serial dilution. The results of the simulation suggested that the effects are non linear with a high degree of dependence on the initial evenness of the community being diluted. A series of incubation experiments using a range of dilutions of raw sewage as an inoculum into sterile sewage was used for comparison to the simulations. The diluted communities were maintained in batch fed reactors (three day retention time) for nine days. The communities were harvested and examined by conventional plating and by molecular analysis of the whole-community DNA using AFLP and T-RFLP. Additional, CLPP analysis was also applied. The effects on richness predicted by the numerical simulations were confirmed by the analyses used. The diluted communities fell into three groups, a low dilution, intermediate dilution, and high dilution group, which corresponded well with the groupings obtained for community richness in simulation. The grouping demonstrated the non-linear nature of dilution of whole communities. Furthermore, the results implied that the undiluted community consisted of a few dominant types accompanied by a number of rare (low abundance) types as is typical in unevenly distributed communities.
NASA Astrophysics Data System (ADS)
Yao, Zhewei; Hu, Zixi; Li, Jinglai
2016-07-01
Many scientific and engineering problems require to perform Bayesian inferences in function spaces, where the unknowns are of infinite dimension. In such problems, choosing an appropriate prior distribution is an important task. In particular, when the function to infer is subject to sharp jumps, the commonly used Gaussian measures become unsuitable. On the other hand, the so-called total variation (TV) prior can only be defined in a finite-dimensional setting, and does not lead to a well-defined posterior measure in function spaces. In this work we present a TV-Gaussian (TG) prior to address such problems, where the TV term is used to detect sharp jumps of the function, and the Gaussian distribution is used as a reference measure so that it results in a well-defined posterior measure in the function space. We also present an efficient Markov Chain Monte Carlo (MCMC) algorithm to draw samples from the posterior distribution of the TG prior. With numerical examples we demonstrate the performance of the TG prior and the efficiency of the proposed MCMC algorithm.
Dilute NiPt alloy interactions with Si
NASA Astrophysics Data System (ADS)
Corni, F.; Grignaffini Gregorio, B.; Ottaviani, G.; Queirolo, G.; Follegot, J. P.
1993-11-01
The reaction between a dilute Ni 95Pt 5 alloy and <111>Si has been investigated as a function of the annealing temperature and time, and the film thickness. Contrary to the concentrate alloys the first phase formed is Ni 2Si and the growth kinetics in the initial steps are similar to the case of pure Ni. Pt segregates in the alloy and its presence slows down the silicide growth rate suggesting that a new mechanism, namely the release of Ni from the alloy, is competing with the diffusion process in the silicide. In all the cases here considered NiSi starts to form only when all the Ni is reacted, indicating that the Pt never reaches high enough concentrations to inhibit the Ni 2Si growth. The further evolution of the system is similar to the ones reported for bilayers and non-dilute alloys. The I-V characteristics measured after annealing give a barrier height of 0.70 ± 0.01 eV.
Modeling the myocardial dilution curve of a pure intravascular indicator.
Lee, J S; Karch, J; Jayaweera, A R; Lindner, J R; Lee, L P; Skyba, D M; Kaul, S
1997-10-01
The dispersion and dilution of contrast medium through the myocardial vasculature is examined first with a serial model comprised of arterial, capillary, and venous components in series to determine their time-concentration curves (TCC) and the myocardial dilution curve (MDC). Analysis of general characteristics shows that the first moment of the MDC, adjusted for that of the aortic TCC and mean transit time (MTT) from the aorta to the first intramyocardial artery, is one-half the MTT of the myocardial vasculature and that the ratio of the area of the MDC and aortic TCC is the fractional myocardial blood volume (MBV). The use of known coronary vascular morphometry and a set of transport functions indicates that the temporal change in MDC is primarily controlled by the MTT. An analysis of several models with heterogeneous flow distributions justifies the procedures to calculate MTT and MBV from the measured MDC. Compared with previously described models, the present model is more general and provides a physical basis for the effects of flow dispersion and heterogeneity on the characteristics of the MDC.
Thermal conductivity and sound attenuation in dilute atomic Fermi gases
Braby, Matt; Chao Jingyi; Schaefer, Thomas
2010-09-15
We compute the thermal conductivity and sound attenuation length of a dilute atomic Fermi gas in the framework of kinetic theory. Above the critical temperature for superfluidity, T{sub c}, the quasiparticles are fermions, whereas below T{sub c}, the dominant excitations are phonons. We calculate the thermal conductivity in both cases. We find that at unitarity the thermal conductivity {kappa} in the normal phase scales as {kappa}{proportional_to}T{sup 3/2}. In the superfluid phase we find {kappa}{proportional_to}T{sup 2}. At high temperature the Prandtl number, the ratio of the momentum and thermal diffusion constants, is 2/3. The ratio increases as the temperature is lowered. As a consequence we expect sound attenuation in the normal phase just above T{sub c} to be dominated by shear viscosity. We comment on the possibility of extracting the shear viscosity of the dilute Fermi gas at unitarity using measurements of the sound absorption length.
Geochemical detection of carbon dioxide in dilute aquifers
Carroll, S; Hao, Y; Aines, R
2009-03-27
Carbon storage in deep saline reservoirs has the potential to lower the amount of CO{sub 2} emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO{sub 2} gas leak into dilute groundwater are important measures for the potential release of CO{sub 2} to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO{sub 2} storage reservoir. Specifically, we address the relationships between CO{sub 2} flux, groundwater flow, detection time and distance. The CO{sub 2} flux ranges from 10{sup 3} to 2 x 10{sup 6} t/yr (0.63 to 1250 t/m{sup 2}/yr) to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure.
Neutron scattering study of dilute supercritical solutions
NASA Astrophysics Data System (ADS)
Cochran, H. D.; Wignall, G. D.; Shah, V. M.; Londono, J. D.; Bienkowski, P. R.
Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope (sup 36)Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast.
Neutron scattering study of dilute supercritical solutions
Cochran, H.D.; Wignall, G.D.; Shah, V.M.; Londono, J.D.; Bienkowski, P.R.
1994-10-01
Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope {sup 36}Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast.
User's manual for GILDA: An infinite lattice diffusion theory calculation
Le, T.T.
1991-11-01
GILDA is a static two-dimensional diffusion theory code that performs either buckling (B[sup 2]) or k-effective (k[sub eff]) calculations for an infinite hexagonal lattice which is constructed by repeating identical seven-cell zones (one cell is one or seven identical homogenized hexes). GILDA was written by J. W. Stewart in 1973. This user's manual is intended to provide all of the information necessary to set up and execute a GILDA calculation and to interpret the output results. It is assumed that the user is familiar with the computer (VAX/VMS or IBM/MVS) and the JOSHUA system database on which the code is implemented. Users who are not familiar with the JOSHUA database are advised to consult additional references to understand the structure of JOSHUA records and data sets before turning to section 4 of this manual. Sections 2 and 3 of this manual serve as a theory document in which the basic diffusion theory and the numerical approximations behind the code are described. Section 4 describes the functions of the program's subroutines. Section 5 describes the input data and tutors the user how to set up a problem. Section 6 describes the output results and the error messages which may be encountered during execution. Users who only wish to learn how to run the code without understanding the theory can start from section 4 and use sections 2 and 3 as references. Finally, the VAX/VMS and the IBM execution command files together with sample input records are provided in the appendices at the end of this manual.
Wave vector modification of the infinite order sudden approximation
NASA Astrophysics Data System (ADS)
Sachs, Judith Grobe; Bowman, Joel M.
1980-10-01
A simple method is proposed to modify the infinite order sudden approximation (IOS) in order to extend its region of quantitative validity. The method involves modifying the phase of the IOS scattering matrix to include a part calculated at the outgoing relative kinetic energy as well as a part calculated at the incoming kinetic energy. An immediate advantage of this modification is that the resulting S matrix is symmetric. We also present a closely related method in which the relative kinetic energies used in the calculation of the phase are determined from quasiclassical trajectory calculations. A set of trajectories is run with the initial state being the incoming state, and another set is run with the initial state being the outgoing state, and the average final relative kinetic energy of each set is obtained. One part of the S-operator phase is then calculated at each of these kinetic energies. We apply these methods to vibrationally inelastic collinear collisions of an atom and a harmonic oscillator, and calculate transition probabilities Pn1→nf for three model systems. For systems which are sudden, or nearly so, the agreement with exact quantum close-coupling calculations is substantially improved over standard IOS ones when Δn=‖nf-ni‖ is large, and the corresponding transition probability is small, i.e., less than 0.1. However, the modifications we propose will not improve the accuracy of the IOS transition probabilities for any collisional system unless the standard form of IOS already gives at least qualitative agreement with exact quantal calculations. We also suggest comparisons between some classical quantities and sudden predictions which should help in determining the validity of the sudden approximation. This is useful when exact quantal data is not available for comparison.
Axial gravitational perturbations of an infinite static line source
NASA Astrophysics Data System (ADS)
Gleiser, Reinaldo J.
2015-03-01
The Levi-Civita metric, which contains a naked singularity that has been interpreted as an infinite static line source, appears, for instance, as the possible end point in the collapse of cylindrically symmetric objects such as shells of dust. The analysis of its gravitational stability should therefore be relevant in the contexts of the cosmic censorship and hoop conjectures. In this paper we study axial gravitational perturbations of the Levi-Civita metric. The perturbations are restricted to axial symmetry but break the cylindrical symmetry of the background metric. We analyze the gauge issues that arise in setting up the appropriate form of the perturbed metric and show that it is possible to restrict the perturbations to diagonal terms but that this does not fix the gauge completely. We derive and solve the perturbation equations. The solutions contain gauge-trivial parts, and we show how to extract the gauge-nontrivial components. We impose appropriate boundary conditions on the solutions and show that these lead to a boundary value problem that determines the allowed functional forms of the perturbation modes. The associated eigenvalues determine a sort of ‘dispersion relation’ for the frequencies and corresponding ‘wave vector’ components. The central result of this analysis is that the spectrum of allowed frequencies contains one unstable (imaginary frequency) mode for every possible choice of the background metric. The completeness of the mode expansion in relation to the initial value problem and to the gauge problem is discussed in detail, and we show that the perturbations contain an unstable component for generic initial data and therefore that the Levi-Civita space times are gravitationally unstable. We also include, for completeness, a set of approximate eigenvalues and examples of the functional form of the solutions.
Cerebral blood flow measured by NMR indicator dilution in cats.
Ewing, J R; Branch, C A; Helpern, J A; Smith, M B; Butt, S M; Welch, K M
1989-02-01
We developed techniques to assess the utility of a nuclear magnetic resonance (NMR) indicator for cerebral blood flow studies in cats, using Freon-22 for the first candidate. A PIN-diode-switched NMR experiment allowed the acquisition of an arterial as well as a cerebral fluorine-19 signal proportional to concentration vs. time in a 1.89 T magnet. Mean +/- SD blood:brain partition coefficients for Freon-22 were estimated at 0.93 +/- 0.08 for gray matter and 0.77 +/- 0.12 for white matter. Using maximum-likelihood curve fitting, estimates of mean +/- SD resting cerebral blood flow were 50 +/- 19 ml/100 g-min for gray matter and 5.0 +/- 2.0 ml/100 g-min for white matter. Hypercapnia produced the expected increases in gray and white matter blood flow. The physiologic effects of Freon-22, including an increase in cerebral blood flow itself with administration of 40% by volume, may limit its use as an indicator. Nevertheless, the NMR techniques described demonstrate the feasibility of fluorine-19-labeled compounds as cerebral blood flow indicators and the promise for their use in humans.
Cerebral blood flow measured by NMR indicator dilution in cats
Ewing, J.R.; Branch, C.A.; Helpern, J.A.; Smith, M.B.; Butt, S.M.; Welch, K.M.
1989-02-01
We developed techniques to assess the utility of a nuclear magnetic resonance (NMR) indicator for cerebral blood flow studies in cats, using Freon-22 for the first candidate. A PIN-diode-switched NMR experiment allowed the acquisition of an arterial as well as a cerebral fluorine-19 signal proportional to concentration vs. time in a 1.89 T magnet. Mean +/- SD blood:brain partition coefficients for Freon-22 were estimated at 0.93 +/- 0.08 for gray matter and 0.77 +/- 0.12 for white matter. Using maximum-likelihood curve fitting, estimates of mean +/- SD resting cerebral blood flow were 50 +/- 19 ml/100 g-min for gray matter and 5.0 +/- 2.0 ml/100 g-min for white matter. Hypercapnia produced the expected increases in gray and white matter blood flow. The physiologic effects of Freon-22, including an increase in cerebral blood flow itself with administration of 40% by volume, may limit its use as an indicator. Nevertheless, the NMR techniques described demonstrate the feasibility of fluorine-19-labeled compounds as cerebral blood flow indicators and the promise for their use in humans.
Cerebral blood flow measured by NMR indicator dilution in cats.
Ewing, J R; Branch, C A; Helpern, J A; Smith, M B; Butt, S M; Welch, K M
1989-02-01
We developed techniques to assess the utility of a nuclear magnetic resonance (NMR) indicator for cerebral blood flow studies in cats, using Freon-22 for the first candidate. A PIN-diode-switched NMR experiment allowed the acquisition of an arterial as well as a cerebral fluorine-19 signal proportional to concentration vs. time in a 1.89 T magnet. Mean +/- SD blood:brain partition coefficients for Freon-22 were estimated at 0.93 +/- 0.08 for gray matter and 0.77 +/- 0.12 for white matter. Using maximum-likelihood curve fitting, estimates of mean +/- SD resting cerebral blood flow were 50 +/- 19 ml/100 g-min for gray matter and 5.0 +/- 2.0 ml/100 g-min for white matter. Hypercapnia produced the expected increases in gray and white matter blood flow. The physiologic effects of Freon-22, including an increase in cerebral blood flow itself with administration of 40% by volume, may limit its use as an indicator. Nevertheless, the NMR techniques described demonstrate the feasibility of fluorine-19-labeled compounds as cerebral blood flow indicators and the promise for their use in humans. PMID:2645693
An ISO 8178 correlation study between raw and dilute exhaust emission sampling systems
Stotler, R.; Human, D.
1995-12-31
Beginning in 1996 the exhaust emissions of off-highway heavy-duty diesel engines between 175--750 hp will be regulated by the EPA. Along with the emission regulations comes the difficulty of establishing a set of standard test procedures which allow engine manufacturers and regulatory agencies to compare emissions data based on similar test methods. In order to remedy this problem, the International Organization for Standardization (ISO) has come up with an exhaust measurement procedure, ISO 8178, that can be applied worldwide to off-highway heavy-duty diesel engines. The ISO 8178 test procedure allows the exhaust emissions to be sampled with either a full flow dilute or raw sampling system. However, the preferred sampling systems are the raw gaseous and mini dilution tunnel (MDT) particulate measurement methods. The main concern of these sampling systems is the demonstration of equivalency to the full flow dilution system that is currently used for the certification of on-highway heavy-duty diesel engines. Using an in-house full flow dilution system and a recently built raw gaseous emissions bench along with a pre-existing MDT, this research was conducted to find the correlation between the two sampling systems. For the gaseous emissions of HC, NO{sub x}, and CO the correlation between the raw and full dilution sampling systems was within 7.0%, 3.0%, and 1.0% respectively. The correlation between the MDT and full dilution particulate sampling systems was within 2.5%. Additional investigation was performed in the area of MDT transfer tube length and its effect on particulate measurement. An experiment was performed to quantify the effect of a wide range of water vapor concentrations on the measurement of NO{sub x}.
NASA Technical Reports Server (NTRS)
Bailey, M. C.
1979-01-01
The calculation of currents induced by a plane wave normally incident upon an infinite strip embedded in a grounded dielectric slab is used to infer the resonant width (or frequency) of rectangular microstrip antennas. By placing the strip inside the dielectric, the effect of a dielectric cover of the same material as the substrate can be included in the calculation of resonant frequency. A comparison with measured results indicated agreement of 1 percent or better for rectangular microstrip antennas constructed on Teflon-fiberglass substrate.
Biodiesel Impact on Engine Lubricant Dilution During Active Regeneration of Aftertreatment Systems
He, X.; Williams, A.; Christensen, E.; Burton, J.; McCormick, R.
2011-12-01
Experiments were conducted with ultra low sulfur diesel (ULSD) and 20% biodiesel blends (B20) to compare lube oil dilution levels and lubricant properties for systems using late in-cylinder fuel injection for aftertreatment regeneration. Lube oil dilution was measured by gas chromatography (GC) following ASTM method D3524 to measure diesel content, by Fourier transform infrared (FTIR) spectrometry following a modified ASTM method D7371 to measure biodiesel content, and by a newly developed back-flush GC method that simultaneously measures both diesel and biodiesel. Heavy-duty (HD) engine testing was conducted on a 2008 6.7L Cummins ISB equipped with a diesel oxidation catalyst (DOC) and diesel particle filter (DPF). Stage one of engine testing consisted of 10 consecutive repeats of a forced DPF regeneration event. This continuous operation with late in-cylinder fuel injection served as a method to accelerate lube-oil dilution. Stage two consisted of 16 hours of normal engine operation over a transient test cycle, which created an opportunity for any accumulated fuel in the oil sump to evaporate. Light duty (LD) vehicle testing was conducted on a 2010 VW Jetta equipped with DOC, DPF and a NOx storage catalyst (NSC). Vehicle testing comprised approximately 4,000 miles of operation on a mileage-accumulation dynamometer (MAD) using the U.S. Environmental Protection Agency's Highway Fuel Economy Cycle because of the relatively low engine oil and exhaust temperatures, and high DPF regeneration frequency of this cycle relative to other cycles examined. Comparison of the lube oil dilution analysis methods suggests that D3524 does not measure dilution by biodiesel. The new back-flush GC method provided analysis for both diesel and biodiesel, in a shorter time and with lower detection limit. Thus all lube oil dilution results in this paper are based on this method. Analysis of the HD lube-oil samples showed only 1.5% to 1.6% fuel dilution for both fuels during continuous
Flag varieties, toric varieties, and suspensions: Three instances of infinite transitivity
Arzhantsev, Ivan V; Zaidenberg, M G; Kuyumzhiyan, Karine G
2012-07-31
We say that a group G acts infinitely transitively on a set X if for every m element of N the induced diagonal action of G is transitive on the cartesian mth power X{sup m} backslash {Delta} with the diagonals removed. We describe three classes of affine algebraic varieties such that their automorphism groups act infinitely transitively on their smooth loci. The first class consists of normal affine cones over flag varieties, the second of nondegenerate affine toric varieties, and the third of iterated suspensions over affine varieties with infinitely transitive automorphism groups. Bibliography: 42 titles.
Functors of White Noise Associated to Characters of the Infinite Symmetric Group
NASA Astrophysics Data System (ADS)
Bożejko, Marek; Guţă, Mădălin
The characters of the infinite symmetric group are extended to multiplicative positive definite functions on pair partitions by using an explicit representation due to Veršik and Kerov. The von Neumann algebra generated by the fields with f in an infinite dimensional real Hilbert space is infinite and the vacuum vector is not separating. For a family depending on an integer N< - 1 an ``exclusion principle'' is found allowing at most ``identical particles'' on the same state:
Dynamical Threshold of Diluteness of Soft Colloids
Chen, Wei-Ren; Do, Changwoo; Egami, T; Falus, Peter; Li, Xin; Liu, Dazhi; Porcar, L.; Sanchez-Diaz, Luis E; Smith, Gregory Scott; Wu, Bin
2014-01-01
The dynamics of soft colloids in solutions is characterized by internal collective motion as well as center-of-mass diffusion. Using neutron scattering we demonstrate that the competition between the relaxation processes associated with these two degrees of freedom results in strong dependence of dynamics and structure on colloid concentration, c, well below the overlap concentration c*. Triggered by the increasing inter-particle collisions, substantial structural dehydration and slowing-down of internal dynamics occurs before geometrically defined colloidal overlap develops. This observation is surprising since it is generally believed that the internal dynamics and conformation of soft colloidal particles essentially remain invariant below c*. The competition between these two relaxation processes gives rise to a new dynamically-defined dilute threshold concentration well below c*.
Crystallization of a dilute atomic dipolar condensate
NASA Astrophysics Data System (ADS)
Bisset, Russell; Blakie, Blair
2016-05-01
A recent experiment found that a dilute BEC of highly-magnetic dysprosium atoms may spontaneously break up into a crystal of droplets, a process reminiscent of the Rosensweig instability [ArXiv:1508.05007]. We dynamically simulate this scenario and find that the standard dipolar Gross-Pitaevskii equation (GPE) cannot explain such a droplet crystal. Indeed, the GPE predicts too much heating during the violent droplet formation, and a droplet lifetime that is much shorter than observed in the experiment. We investigate the requisite properties of the unknown stabilization mechanism, and find that an effective repulsive interaction with a higher order density dependence than the usual two-body interactions is required to quantitatively reproduce the experimental results.
Dilute acid saccharification of lignocellulosic biomass
Penner, M.H.; Hashimoto, A.G.
1995-12-01
Aqueous dilute sulfuric acid solutions have been evaluated in terms of their effectiveness for the saccharification of the insoluble xylan fraction of poplar and switchgrass feedstocks. Acid concentrations ranging from .6 to 1.2% have been tested at temperatures ranging from 120 to 160{degrees}C. Treatments at optimum time, temperature, and acid combinations provided xylose yields of approximately 90% theoretical. Rate constants associated with xylan hydrolysis and xylose degradation for each of the feed-stocks have been evaluated. In general, optimum yields were associated with high temperature treatments for relatively short reaction times. Results from our laboratory will be presented with reference to previously published studies on hemicellulose saccharification and in the general context of converting lignocellulosic biomass to useful products.
Shock waves in a dilute granular gas
NASA Astrophysics Data System (ADS)
Reddy, M. H. Lakshminarayana; Ansumali, Santosh; Alam, Meheboob
2014-12-01
We study the evolution of shock waves in a dilute granular gas which is modelled using three variants of hydrodynamic equations: Euler, 10-moment and 14-moment models. The one-dimensional shock-wave problem is formulated and the resulting equations are solved numerically using a relaxation-type scheme. Focusing on the specific case of blast waves, the results on the density, the granular temperature, the skew temperature, the heat flux and the fourth moment are compared among three models. We find that the shock profiles are smoother for the 14-moment model compared to those predicted by the standard Euler equations. A shock-splitting phenomenon is observed in the skew granular temperature profiles for a blast wave.
Negative magnetophoresis in diluted ferrofluid flow.
Hejazian, Majid; Nguyen, Nam-Trung
2015-07-21
We report magnetic manipulation of non-magnetic particles suspended in diluted ferrofluid. Diamagnetic particles were introduced into a circular chamber to study the extent of their deflection under the effect of a non-uniform magnetic field of a permanent magnet. Since ferrofluid is a paramagnetic medium, it also experiences a bulk magnetic force that in turn induces a secondary flow opposing the main hydrodynamic flow. Sheath flow rate, particle size, and magnetic field strength were varied to examine this complex behaviour. The combined effect of negative magnetophoresis and magnetically induced secondary flow leads to various operation regimes, which can potentially find applications in separation, trapping and mixing of diamagnetic particles such as cells in a microfluidic system. PMID:26054840
NASA Astrophysics Data System (ADS)
Maldonado-Mundo, Daniel; He, Lianyi; Öhberg, Patrik; Valiente, Manuel
2014-03-01
We study repulsive Fermi gases with Rashba spin-orbit coupling in two and three dimensions when they are dilute enough that a single branch of the spectrum is occupied in the non-interacting ground state. We develop an effective renormalizable theory for fermions in the lower branch and obtain the energy of the system in three dimensions to second order in the renormalized coupling constant. We then exploit the non-Galilean-relativistic nature of spin-orbit coupled gases. We find that at finite momentum, the two-dimensional Fermi sea is deformed in a non-trivial way. Using mean-field theory to include interactions, we show that the ground-state of the system acquires a finite momentum, and is consequently deformed, when the interaction is stronger than a critical value. Heriot-Watt University. CM-DTC. SUPA. EPSRC.
Diluted magnetic semiconductors with narrow band gaps
NASA Astrophysics Data System (ADS)
Gu, Bo; Maekawa, Sadamichi
2016-10-01
We propose a method to realize diluted magnetic semiconductors (DMSs) with p - and n -type carriers by choosing host semiconductors with a narrow band gap. By employing a combination of the density function theory and quantum Monte Carlo simulation, we demonstrate such semiconductors using Mn-doped BaZn2As2 , which has a band gap of 0.2 eV. In addition, we found a nontoxic DMS Mn-doped BaZn2Sb2 , of which the Curie temperature Tc is predicted to be higher than that of Mn-doped BaZn2As2 , the Tc of which was up to 230 K in a recent experiment.
Recombinant UL30 antigen-based single serum dilution ELISA for detection of duck viral enteritis.
Aravind, S; Patil, B R; Dey, Sohini; Mohan, C Madhan
2012-11-01
A recombinant UL30 antigen-based single serum dilution enzyme linked immunosorbent assay (ELISA) was developed to measure specific antibody in the sera of ducks against duck enteritis virus (DEV). The partial UL30 gene of DEV was cloned, expressed, purified and tested for its diagnostic use by designing a single serum dilution enzyme linked immuno-sorbent assay (ELISA). A total of 226 duck sera samples were tested using the assay. A linear relationship was found between the predicted antibody titres at a single working dilution of 1:100 and the corresponding serum titres observed as determined by the standard serial dilution method. Regression analysis was used to determine a standard curve from which an equation was derived which demonstrated this correlation. The equation was then used to convert the corrected absorbance readings of the single working dilution directly into the predicted ELISA antibody titres. The assay proved to be specific, sensitive and accurate as compared to the virus neutralization test with a specificity, sensitivity and accuracy being 96%, 95% and 95% respectively.
Yue, G.; Yan, B.; Ganguly, G.; Yang, J.; Guha, S.; Teplin, C. W.; Williamson, D. L.
2006-01-01
We have carried out a systematic study on metastability of n-i-p nc-Si:H solar cells with various hydrogen dilution profiles and correlate the results with the material structural properties. We find that the nc-Si:H single-junction cells with a hydrogen dilution profile show not only improved initial efficiency, but also better stability than those with a constant hydrogen dilution. Raman measurements using different excitation wavelengths show that the cells with the improved stability due to the hydrogen dilution profiling have a significant amorphous component, especially near the i/p interface. We speculate that the amorphous volume fraction in the material is not the key parameter for determining the stability of nc-Si:H cells. Other factors, such as the distribution and structure of the amorphous phase and the grain boundary regions, can affect the overall cell stability. By carefully optimizing the hydrogen dilution profiling, we have achieved initial and stable efficiencies of 9.0% and 8.5% in a nc-Si:H single junction, and 14.1% and 13.3% in an a-Si:H/nc-Si:H/nc-Si:H triple-junction structure, respectively.
The diversity-disease relationship: evidence for and criticisms of the dilution effect.
Huang, Z Y X; VAN Langevelde, F; Estrada-Peña, A; Suzán, G; DE Boer, W F
2016-08-01
The dilution effect, that high host species diversity can reduce disease risk, has attracted much attention in the context of global biodiversity decline and increasing disease emergence. Recent studies have criticized the generality of the dilution effect and argued that it only occurs under certain circumstances. Nevertheless, evidence for the existence of a dilution effect was reported in about 80% of the studies that addressed the diversity-disease relationship, and a recent meta-analysis found that the dilution effect is widespread. We here review supporting and critical studies, point out the causes underlying the current disputes. The dilution is expected to be strong when the competent host species tend to remain when species diversity declines, characterized as a negative relationship between species' reservoir competence and local extinction risk. We here conclude that most studies support a negative competence-extinction relationship. We then synthesize the current knowledge on how the diversity-disease relationship can be modified by particular species in community, by the scales of analyses, and by the disease risk measures. We also highlight the complex role of habitat fragmentation in the diversity-disease relationship from epidemiological, evolutionary and ecological perspectives, and construct a synthetic framework integrating these three perspectives. We suggest that future studies should test the diversity-disease relationship across different scales and consider the multiple effects of landscape fragmentation. PMID:27041655
Detection of dilute organic acids in water by inelastic tunneling spectroscopy
NASA Technical Reports Server (NTRS)
Skarlatos, Y.; Barker, R. C.; Haller, G. L.; Yelon, A.
1974-01-01
Study of inelastic electron tunneling spectroscopy (IETS) spectra obtained from junctions exposed to dilute solutions of organic molecules in both liquid and vapor phases. The results indicate that it is possible in principle to detect the presence and to measure the concentration of at least some organic molecules in dilute aqueous solution by means of the IETS technique. Some fine points pertaining to the application of this technique are discussed, and it is pointed out that through appropriate refinements IETS may become a valuable tool for analytical water chemistry.
Muon hyperfine fields in iron and its dilute alloys
NASA Technical Reports Server (NTRS)
Stronach, C. E.; Squire, K. R.; Arrott, A. S.; Patterson, B. D.; Heinrich, B.; Lankford, W. F.; Fiory, A. T.; Kossler, W. J.; Singh, J. J.
1981-01-01
The temperature dependence of the interstitial magnetic field, B, as determined by the rotation of the spin of the muon, has been measured for dilute polycrystalline iron alloys with Mo, Ti, and Nb additions over a temperature range of 240 to 633 K. In all cases the behaviors differ from one another and from the Fe(Al) alloys previously studied. B, which is negative with respect to the magnetization, is increased in magnitude by Al and Mo, and decreased greatly by Ti. The addition of Nb creates a two-phase alloy from which the role of heterogeneity and/or strain on B in iron can be assessed. If the temperature dependence of the hyperfine field extracted from B for Fe(Mo) alloys is interpreted on the model previously used to discuss the Fe(Al) data, then the muon must be attracted to the Mo atom while repelled by the Al atoms as the temperature decreases.
Dilute Aperture Visible Nulling Coronagraph Imaging (DAViNCI)
NASA Technical Reports Server (NTRS)
Shao, Michael; Levine, B. M.; Vasisht, G.; Lane, B. F.; Woodruff, R.; Vasudevan, G.; Samuele R.; Harvey, K.; Clampin, M.; Lyon, R.; Guyon, O.; Tolls, V.
2008-01-01
The presentation focuses on instrument and mission overview, science case, Team X study, and technology status. Topics include DAViNCI study milestones, number of targets versus inner working angle, planet orbit and IWA, combiner/nuller instrument, DAViNCI Team X costs, technology status and near future plans, and deep laser null 1.23 x 10(exp -7) suppression. Summary points are: dilute aperture concept advantages, lower cost than a comparable 7-8m coronagraph working at 2 lambda/D, technology progress prior to 2008 was seriously limited by available funding but showed 1e-y suppression (2006) of laser light needed for 1e-9 to approximately 1e-10 contrast, and current technology effort is off to a fast date with a demonstration of less than 100pm wavefront measurement in Nov 08.
Scanning Hall probe microscopy of a diluted magnetic semiconductor
Kweon, Seongsoo; Samarth, Nitin; Lozanne, Alex de
2009-05-01
We have measured the micromagnetic properties of a diluted magnetic semiconductor as a function of temperature and applied field with a scanning Hall probe microscope built in our laboratory. The design philosophy for this microscope and some details are described. The samples analyzed in this work are Ga{sub 0.94}Mn{sub 0.06}As films grown by molecular beam epitaxy. We find that the magnetic domains are 2-4 mum wide and fairly stable with temperature. Magnetic clusters are observed above T{sub C}, which we ascribe to MnAs defects too small and sparse to be detected by a superconducting quantum interference device magnetometer.
Positive ion polymerization in hydrogen diluted silane plasmas
Nunomura, S.; Kondo, M.
2008-12-08
Mass spectra of positive ions (cations) and neutrals have been measured in hydrogen diluted silane plasmas at gas pressures of 0.1-10 Torr. The mass spectrum of ions changes with the pressure, while that of neutrals maintains a similar shape. The dominant ion species varies from a hydrogen ion group at < or approx. 0.5 Torr to a monosilicon hydride ion group at {approx_equal}0.5-1 Torr and polysilicon hydride ion groups at > or approx. 1 Torr, which is determined from ionization channels and consecutive ion-molecule reactions. The ion bombardment is suppressed with the pressure, from several tens of eV at < or approx. 1 Torr to a few eV at > or approx. 7 Torr.
40 CFR 90.421 - Dilute gaseous exhaust sampling and analytical system description.
Code of Federal Regulations, 2013 CFR
2013-07-01
...) Conform to the continuous NOX, CO, or CO2 sampling and analysis system to the specifications of 40 CFR... condensation at any point in the dilution system. Gaseous emission samples may be taken directly from this... requirement that condensation does not occur. The temperature measuring system (sensors and readout) must...
40 CFR 90.421 - Dilute gaseous exhaust sampling and analytical system description.
Code of Federal Regulations, 2011 CFR
2011-07-01
...) Conform to the continuous NOX, CO, or CO2 sampling and analysis system to the specifications of 40 CFR... condensation at any point in the dilution system. Gaseous emission samples may be taken directly from this... requirement that condensation does not occur. The temperature measuring system (sensors and readout) must...
40 CFR 90.421 - Dilute gaseous exhaust sampling and analytical system description.
Code of Federal Regulations, 2014 CFR
2014-07-01
...) Conform to the continuous NOX, CO, or CO2 sampling and analysis system to the specifications of 40 CFR... condensation at any point in the dilution system. Gaseous emission samples may be taken directly from this... requirement that condensation does not occur. The temperature measuring system (sensors and readout) must...
40 CFR 90.421 - Dilute gaseous exhaust sampling and analytical system description.
Code of Federal Regulations, 2012 CFR
2012-07-01
...) Conform to the continuous NOX, CO, or CO2 sampling and analysis system to the specifications of 40 CFR... condensation at any point in the dilution system. Gaseous emission samples may be taken directly from this... requirement that condensation does not occur. The temperature measuring system (sensors and readout) must...
40 CFR 1065.140 - Dilution for gaseous and PM constituents.
Code of Federal Regulations, 2014 CFR
2014-07-01
... nitrogen. References in this part to “dilution air” may include any of these. For gaseous emission... for background concentrations (40 CFR 1066.610 for vehicle testing). (2) Measure these background... raw exhaust sample for any batch or continuous PM emission sampling over any transient duty cycle,...
40 CFR 1065.546 - Validation of minimum dilution ratio for PM batch sampling.
Code of Federal Regulations, 2011 CFR
2011-07-01
... Specified Duty Cycles § 1065.546 Validation of minimum dilution ratio for PM batch sampling. Use continuous flows and/or tracer gas concentrations for transient and ramped modal cycles to validate the minimum... mode-average values instead of continuous measurements for discrete mode steady-state duty...
40 CFR 1065.546 - Validation of minimum dilution ratio for PM batch sampling.
Code of Federal Regulations, 2012 CFR
2012-07-01
... Specified Duty Cycles § 1065.546 Validation of minimum dilution ratio for PM batch sampling. Use continuous flows and/or tracer gas concentrations for transient and ramped modal cycles to validate the minimum... mode-average values instead of continuous measurements for discrete mode steady-state duty...
40 CFR 1065.546 - Validation of minimum dilution ratio for PM batch sampling.
Code of Federal Regulations, 2010 CFR
2010-07-01
... Specified Duty Cycles § 1065.546 Validation of minimum dilution ratio for PM batch sampling. Use continuous flows and/or tracer gas concentrations for transient and ramped modal cycles to validate the minimum... mode-average values instead of continuous measurements for discrete mode steady-state duty...
40 CFR 1065.546 - Verification of minimum dilution ratio for PM batch sampling.
Code of Federal Regulations, 2014 CFR
2014-07-01
... Specified Duty Cycles § 1065.546 Verification of minimum dilution ratio for PM batch sampling. Use continuous flows and/or tracer gas concentrations for transient and ramped-modal cycles to verify the minimum... mode-average values instead of continuous measurements for discrete mode steady-state duty...
10 CFR 35.190 - Training for uptake, dilution, and excretion studies.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 10 Energy 1 2012-01-01 2012-01-01 false Training for uptake, dilution, and excretion studies. 35.190 Section 35.190 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Unsealed...) Mathematics pertaining to the use and measurement of radioactivity; (D) Chemistry of byproduct material...
10 CFR 35.190 - Training for uptake, dilution, and excretion studies.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 10 Energy 1 2013-01-01 2013-01-01 false Training for uptake, dilution, and excretion studies. 35.190 Section 35.190 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Unsealed...) Mathematics pertaining to the use and measurement of radioactivity; (D) Chemistry of byproduct material...
10 CFR 35.190 - Training for uptake, dilution, and excretion studies.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 10 Energy 1 2014-01-01 2014-01-01 false Training for uptake, dilution, and excretion studies. 35.190 Section 35.190 Energy NUCLEAR REGULATORY COMMISSION MEDICAL USE OF BYPRODUCT MATERIAL Unsealed...) Mathematics pertaining to the use and measurement of radioactivity; (D) Chemistry of byproduct material...
ERIC Educational Resources Information Center
Pety, Stephen J.; Lu, Hang; Thio, Yonathan S.
2011-01-01
This paper describes a student laboratory experiment to determine the molecular weight of a polymer sample by measuring the viscosity of dilute polymer solutions in a PDMS microfluidic viscometer. Sample data are given for aqueous solutions of poly(ethylene oxide) (PEO). A demonstration of shear thinning behavior using the microviscometer is…
Depth Matters: Soil pH and dilution effects in the northern Great Plains
Technology Transfer Automated Retrieval System (TEKTRAN)
In the northern Great Plans (NGP), surface sampling depths of 0-15.2 cm or 0-20.3 cm are suggested for testing soil characteristics such as pH. However, acidification is often most pronounced near-surface (e.g., <10 cm). Thus, sampling deeper can potentially dilute (increase) pH measurements and the...
Lung volumes in man immersed to the neck: dilution and plethysmographic techniques.
Robertson, C H; Engle, C M; Bradley, M E
1978-05-01
Previous studies of lung volumes during immersion have utilized dilution techniques for residual volume. We have compared lung volumes obtained by the use of a dual inert gas dilution technique with those determined by the Boyle's law technique in a plethysmograph designed to allow measurements in air and submersed to the neck in water. Both techniques gave similar results dry, but during immersion the dilution residual volume (RV) was 0.200 liter (16%) lower than the plethysmographic value (P greater than 0.001), which suggests that there is a significant amount of gas trapping during immersion due to breathing at low lung volumes and the central shift of blood. The unchanged RV due to hydrostatic force on the chest wall is balanced by the tendency to increase RV due to vascular congestion, which increases closing volume and stiffens the lung to compression. PMID:649469
Infinite-impulse-response models of the head-related transfer function
NASA Astrophysics Data System (ADS)
Kulkarni, Abhijit; Colburn, H. Steven
2004-04-01
Head-related transfer functions (HRTFs) measured from human subjects were approximated using infinite-impulse-response (IIR) filter models. Models were restricted to rational transfer functions (plus simple delays) so that specific models are characterized by the locations of poles and zeros in the complex plane. The all-pole case (with no nontrivial zeros) is treated first using the theory of linear prediction. Then the general pole-zero model is derived using a weighted-least-squares (WLS) formulation of the modified least-squares problem proposed by Kalman (1958). Both estimation algorithms are based on solutions of sets of linear equations and result in efficient computational schemes to find low-order model HRTFs. The validity of each of these two low-order models was assessed in psychophysical experiments. Specifically, a four-interval, two-alternative, forced-choice paradigm was used to test the discriminability of virtual stimuli constructed from empirical and model HRTFs for corresponding locations. For these experiments, the stimuli were 80 ms, noise tokens generated from a wideband noise generator. Results show that sounds synthesized through model HRTFs were indistinguishable from sounds synthesized from original HRTF measurements for the majority of positions tested. The advantages of the techniques described here are the computational efficiencies achieved for low-order IIR models. Properties of the all-pole and pole-zero estimators are discussed in the context of low-order HRTF representations, and implications for basic and applied contexts are considered.
Circulation pumps as structure-borne sound sources: emission to semi-infinite pipe systems
NASA Astrophysics Data System (ADS)
Qi, N.; Gibbs, B. M.
2003-06-01
Circulation pumps are an important source of noise from domestic central heating systems. Pumps can generate airborne, liquid-borne and structure-borne sound and although standards exist for airborne and liquid-borne sources, none do for structure-borne sources. This is primarily because the structure-borne acoustic power delivered by the pump not only depends on the pump but also on the connected receiving system, which can be a complicated combination of pipes, valves and radiators. Also pumps deliver liquid-borne and structure-borne acoustic power simultaneously and their relative contributions to the sound radiated from the pipe system is not obviously obtainable. The approach proposed is to estimate the emission from the pump into semi-infinite pipes of material and cross-section typical of heating systems. Then to estimate the 'mixing' effect of bends, joints and other pipe discontinuities, due to wave mode conversion, as described in a companion paper. In the present paper, it is demonstrated that the structure-borne power can be calculated from the measured free velocity and mobility of the pump for each component of vibration and from receiver mobilities of idealized pipe systems. The structure-borne power is compared with the liquid-borne power measured directly by intensimetry.
Radiotracer Dilution Method for Mercury Inventory Study in Electrolytic Cells
Sugiharto; Su'ud, Zaki; Kurniadi, Rizal; Waris, Abdul; Santoso, Sigit Budi; Abidin, Zainal; Santoso, Gatot Budi
2010-06-22
Purpose of the experiment is to demonstrate feasibility the use of radiotracer to measure weight of mercury in electrolytic cells of soda industry. The weight of mercury in each cell of the plant is designed approximately 1700 kg. Radiotracer is prepared by mixing {sup 203}Hg radioactive mercury with 2400 g of inactive mercury in a bath. The respective precisely weighted mercury aliquots to be injected into the cells are prepared by pouring approximately 130 g of radioactive mercury taken from the bath into 13 standard vials, in accordance with the number of the cells tested. Four standard references prepared by further dilution of {+-}2 g active mercury taken from the bath to obtain the dilution factors range of 12,000 to 20,000 from which the calibration graph is constructed. The injection process is conducting by pouring the radioactive mercury from aliquots into the flowing mercury at the inlet side of the cell and allows them to mix thoroughly. It is assumed that the mass of the radiotracer injected into a closed system remains constant, at least during the period of the test. From this experiment it was observed that the mixing time is two days after injection of radioactive mercury. The inactive mercury in each electrolytic cell calculated by the radiotracer method is of the range 1351.529 kg to 1966.354 kg with maximum error (95% confidence) is 1.52 %. The accuracy of measurement of the present method is better than gravimetric one which accounts 4 % of error on average.
Liang, Xiao; Wang, Linshan; Wang, Yangfan; Wang, Ruili
2016-09-01
In this paper, we focus on the long time behavior of the mild solution to delayed reaction-diffusion Hopfield neural networks (DRDHNNs) driven by infinite dimensional Wiener processes. We analyze the existence, uniqueness, and stability of this system under the local Lipschitz function by constructing an appropriate Lyapunov-Krasovskii function and utilizing the semigroup theory. Some easy-to-test criteria affecting the well-posedness and stability of the networks, such as infinite dimensional noise and diffusion effect, are obtained. The criteria can be used as theoretic guidance to stabilize DRDHNNs in practical applications when infinite dimensional noise is taken into consideration. Meanwhile, considering the fact that the standard Brownian motion is a special case of infinite dimensional Wiener process, we undertake an analysis of the local Lipschitz condition, which has a wider range than the global Lipschitz condition. Two samples are given to examine the availability of the results in this paper. Simulations are also given using the MATLAB.
The correlation length in thin film and semi-infinite medium
NASA Astrophysics Data System (ADS)
Korneta, W.; Pytel, Z.
1983-03-01
Correlation lengths in directions parallel and perpendicular to a surface of a thin ferromagnetic film and a semi-infinite ferromagnet are calculated. Their dependences both on temperature and distance to a surface are discussed.
High-energy scatterings in infinite-derivative field theory and ghost-free gravity
NASA Astrophysics Data System (ADS)
Talaganis, Spyridon; Mazumdar, Anupam
2016-07-01
In this paper, we will consider scattering diagrams in the context of infinite-derivative theories. First, we examine a finite-order, higher-derivative scalar field theory and find that we cannot eliminate the growth of scattering diagrams for large external momenta. Then, we employ an infinite-derivative scalar toy model and obtain that the external momentum dependence of scattering diagrams is convergent as the external momenta become very large. In order to eliminate the external momentum growth, one has to dress the bare vertices of the scattering diagrams by considering renormalised propagator and vertex loop corrections to the bare vertices. Finally, we investigate scattering diagrams in the context of a scalar toy model which is inspired by a ghost-free and singularity-free infinite-derivative theory of gravity, where we conclude that infinite derivatives can eliminate the external momentum growth of scattering diagrams and make the scattering diagrams convergent in the ultraviolet.
State feedback control of real-time discrete event systems with infinite states
NASA Astrophysics Data System (ADS)
Park, Seong-Jin; Cho, Kwang-Hyun
2015-05-01
In this paper, we study a state feedback supervisory control of timed discrete event systems (TDESs) with infinite number of states modelled as timed automata. To this end, we represent a timed automaton with infinite number of untimed states (called locations) by a finite set of conditional assignment statements. Predicates and predicate transformers are employed to finitely represent the behaviour and specification of a TDES with infinite number of locations. In addition, the notion of clock regions in timed automata is used to identify the reachable states of a TDES with an infinite time space. For a real-time specification described as a predicate, we present the controllability condition for the existence of a state feedback supervisor that restricts the behaviour of the controlled TDES within the specification.
Dilute acid/metal salt hydrolysis of lignocellulosics
Nguyen, Quang A.; Tucker, Melvin P.
2002-01-01
A modified dilute acid method of hydrolyzing the cellulose and hemicellulose in lignocellulosic material under conditions to obtain higher overall fermentable sugar yields than is obtainable using dilute acid alone, comprising: impregnating a lignocellulosic feedstock with a mixture of an amount of aqueous solution of a dilute acid catalyst and a metal salt catalyst sufficient to provide higher overall fermentable sugar yields than is obtainable when hydrolyzing with dilute acid alone; loading the impregnated lignocellulosic feedstock into a reactor and heating for a sufficient period of time to hydrolyze substantially all of the hemicellulose and greater than 45% of the cellulose to water soluble sugars; and recovering the water soluble sugars.
NASA Astrophysics Data System (ADS)
Catrysse, Peter B.; Fan, Shanhui
2015-03-01
Media that are described by extreme electromagnetic parameters, such as very large/small permittivity/permeability, have generated significant fundamental and applied interest in recent years. Notable examples include epsilon-near-zero, ultra-low refractive-index, and ultra-high refractive-index materials. Many photonic structures, such as waveguides, lenses, and photonic band gap materials, benefit greatly from the large index contrast provided by such media. In this paper, I discuss our recent work on media with infinite anisotropy, i.e., infinite permittivity (permeability) in one direction and finite in the other directions. As an illustration of the unusual optical behaviors that result from infinite anisotropy, I describe efficient light transport in deep-subwavelength apertures filled with infinitely anisotropic media. I then point out some of the opportunities that exist for controlling light at the nano-scale using infinitely anisotropic media by themselves. First, I show that a single medium with infinite anisotropy enables diffraction-free propagation of deep-subwavelength beams. Next, I demonstrate interfaces between two infinitely anisotropic media that are impedancematched for complete deep-subwavelength beams and enable reflection-free routing with zero bend radius that is entirely free from diffraction effects even when deep-subwavelength information is encoded on the beams. These behaviors indicate an unprecedented possibility to use media with infinite anisotropy to manipulate beams with deepsubwavelength features, including complete images. To illustrate physical realizability, I demonstrate a metamaterial design using existing materials in a planar geometry, which can be implemented using well-established nanofabrication techniques. This approach provides a path to deep-subwavelength routing of information-carrying beams and far-field imaging unencumbered by diffraction and reflection.
NASA Technical Reports Server (NTRS)
Banks, H. T.; Wang, C.
1989-01-01
A general approximation framework is discussed for computation of optimal feedback controls in linear quadratic regular problems for nonautonomous parabolic distributed parameter systems. This is done in the context of a theoretical framework using general evolution systems in infinite dimensional Hilbert spaces. Conditions are discussed for preservation under approximation of stabilizability and detectability hypotheses on the infinite dimensional system. The special case of periodic systems is also treated.
Infinite product expansion of the Fokker–Planck equation with steady-state solution
Martin, R. J.; Craster, R. V.; Kearney, M. J.
2015-01-01
We present an analytical technique for solving Fokker–Planck equations that have a steady-state solution by representing the solution as an infinite product rather than, as usual, an infinite sum. This method has many advantages: automatically ensuring positivity of the resulting approximation, and by design exactly matching both the short- and long-term behaviour. The efficacy of the technique is demonstrated via comparisons with computations of typical examples. PMID:26346100
Harding, R.M.; Martinson, J.J.; Flint, J.; Clegg, J.B.; Boyce, A.J. )
1993-11-01
Extensive allelic diversity in variable numbers of tandem repeats (VNTRs) has been discovered in the human genome. For population genetic studies of VNTRs, such as forensic applications, it is important to know whether a neutral mutation-drift balance of VNTR polymorphism can be represented by the infinite alleles model. The assumption of the infinite alleles model that each new mutant is unique is very likely to be violated by unequal sister chromatid exchange (USCE), the primary process believed to generate VNTR mutants. The authors show that increasing both mutation rates and misalignment constraint for intrachromosomal recombination in a computer simulation model reduces simulated VNTR diversity below the expectations of the infinite alleles model. Maximal constraint, represented as slippage of single repeats, reduces simulated VNTR diversity to levels expected from the stepwise mutation model. Although misalignment rule is the more important variable, mutation rate also has an effect. At moderate rates of USCE, simulated VNTR diversity fluctuates around infinite alleles expectation. However, if rates of USCE are high, as for hypervariable VNTRs, simulated VNTR diversity is consistently lower than predicted by the infinite alleles model. This has been observed for many VNTRs and accounted for by technical problems in distinguishing alleles of neighboring size classes. The authors use sampling theory to confirm the intrinsically poor fit to the infinite model of both simulated VNTR diversity and observed VNTR polymorphisms sampled from two Papua New Guinean populations. 25 refs., 20 figs., 4 tabs.
NASA Astrophysics Data System (ADS)
Camacho, Miguel; Boix, Rafael R.; Medina, Francisco
2016-06-01
The authors present a computationally efficient technique for the analysis of extraordinary transmission through both infinite and truncated periodic arrays of slots in perfect conductor screens of negligible thickness. An integral equation is obtained for the tangential electric field in the slots both in the infinite case and in the truncated case. The unknown functions are expressed as linear combinations of known basis functions, and the unknown weight coefficients are determined by means of Galerkin's method. The coefficients of Galerkin's matrix are obtained in the spatial domain in terms of double finite integrals containing the Green's functions (which, in the infinite case, is efficiently computed by means of Ewald's method) times cross-correlations between both the basis functions and their divergences. The computation in the spatial domain is an efficient alternative to the direct computation in the spectral domain since this latter approach involves the determination of either slowly convergent double infinite summations (infinite case) or slowly convergent double infinite integrals (truncated case). The results obtained are validated by means of commercial software, and it is found that the integral equation technique presented in this paper is at least two orders of magnitude faster than commercial software for a similar accuracy. It is also shown that the phenomena related to periodicity such as extraordinary transmission and Wood's anomaly start to appear in the truncated case for arrays with more than 100 (10 ×10 ) slots.