Poissonian steady states: From stationary densities to stationary intensities
NASA Astrophysics Data System (ADS)
Eliazar, Iddo
2012-10-01
Markov dynamics are the most elemental and omnipresent form of stochastic dynamics in the sciences, with applications ranging from physics to chemistry, from biology to evolution, and from economics to finance. Markov dynamics can be either stationary or nonstationary. Stationary Markov dynamics represent statistical steady states and are quantified by stationary densities. In this paper, we generalize the notion of steady state to the case of general Markov dynamics. Considering an ensemble of independent motions governed by common Markov dynamics, we establish that the entire ensemble attains Poissonian steady states which are quantified by stationary Poissonian intensities and which hold valid also in the case of nonstationary Markov dynamics. The methodology is applied to a host of Markov dynamics, including Brownian motion, birth-death processes, random walks, geometric random walks, renewal processes, growth-collapse dynamics, decay-surge dynamics, Ito diffusions, and Langevin dynamics.
Stability of Stationary Solutions of the Multifrequency Radiation Diffusion Equations
Hald, O H; Shestakov, A I
2004-01-20
A nondimensional model of the multifrequency radiation diffusion equation is derived. A single material, ideal gas, equation of state is assumed. Opacities are proportional to the inverse of the cube of the frequency. Inclusion of stimulated emission implies a Wien spectrum for the radiation source function. It is shown that the solutions are uniformly bounded in time and that stationary solutions are stable. The spatially independent solutions are asymptotically stable, while the spatially dependent solutions of the linearized equations approach zero.
Numerical methods for finding stationary gravitational solutions
NASA Astrophysics Data System (ADS)
Dias, Óscar J. C.; Santos, Jorge E.; Way, Benson
2016-07-01
The wide applications of higher dimensional gravity and gauge/gravity duality have fuelled the search for new stationary solutions of the Einstein equation (possibly coupled to matter). In this topical review, we explain the mathematical foundations and give a practical guide for the numerical solution of gravitational boundary value problems. We present these methods by way of example: resolving asymptotically flat black rings, singly spinning lumpy black holes in anti-de Sitter (AdS), and the Gregory–Laflamme zero modes of small rotating black holes in AdS{}5× {S}5. We also include several tools and tricks that have been useful throughout the literature.
Self-Organized Stationary States of Tokamaks.
Jardin, S C; Ferraro, N; Krebs, I
2015-11-20
We demonstrate that in a 3D resistive magnetohydrodynamic simulation, for some parameters it is possible to form a stationary state in a tokamak where a saturated interchange mode in the center of the discharge drives a near helical flow pattern that acts to nonlinearly sustain the configuration by adjusting the central loop voltage through a dynamo action. This could explain the physical mechanism for maintaining stationary nonsawtoothing "hybrid" discharges, often referred to as "flux pumping." PMID:26636854
Self-Organized Stationary States of Tokamaks
Jardin, S. C.; Ferraro, N.; Krebs, I.
2015-11-01
We demonstrate that in a 3D resistive magnetohydrodynamic simulation, for some parameters it is possible to form a stationary state in a tokamak where a saturated interchange mode in the center of the discharge drives a near helical flow pattern that acts to nonlinearly sustain the configuration by adjusting the central loop voltage through a dynamo action. This could explain the physical mechanism for maintaining stationary nonsawtoothing "hybrid" discharges, often referred to as "flux pumping."
Self-Organized Stationary States of Tokamaks
Jardin, S. C.; Ferraro, N.; Krebs, I.
2015-11-17
We demonstrate that in a 3D resistive magnetohydrodynamic (MHD) simulation, for some parameters it is possible to form a stationary state in a tokamak where a saturated interchange mode in the center of the discharge drives a near helical flow pattern that acts to non-linearly sustain the configuration by adjusting the central loop voltage through a dynamo action. This could explain the physical mechanism for maintaining stationary non-sawtoothing “hybrid” discharges, often referred to as “flux-pumping”.
Stationary solutions of the Dirac equation in the gravitational field of a charged black hole
Dokuchaev, V. I. Eroshenko, Yu. N.
2013-07-15
A stationary solution of the Dirac equation in the metric of a Reissner-Nordstroem black hole has been found. Only one stationary regular state outside the black hole event horizon and only one stationary regular state below the Cauchy horizon are shown to exist. The normalization integral of the wave functions diverges on both horizons if the black hole is non-extremal. This means that the solution found can be only the asymptotic limit of a nonstationary solution. In contrast, in the case of an extremal black hole, the normalization integral is finite and the stationary regular solution is physically self-consistent. The existence of quantum levels below the Cauchy horizon can affect the final stage of Hawking black hole evaporation and opens up the fundamental possibility of investigating the internal structure of black holes using quantum tunneling between external and internal states.
Static and stationary multiple soliton solutions to the Einstein equations
Letelier, P.S.
1985-03-01
The application of the Belinsky--Zakharov solution-generating technique, i.e., the inverse scattering method, to generate stationary axially symmetric solutions to the vacuum Einstein equations is reduced to a single quadrature when the seed solution is diagonal. The possibility of having real odd-number soliton solutions is investigated. These solutions represent solitonic perturbations of Euclidean metrics. The possibility of using instantons as seed solutions is also investigated. The one- and two-soliton solutions generated from a diagonal seed solution are studied. As an application, a unified derivation of some well-known static solutions, like the Schwarzschild metric and the Chazy--Curzon metric, as well as other new metrics is presented. By using these metrics as seed solutions, some known stationary solutions, like the Kerr-NUT metric, the double Kerr metric, and the rotating Weyl C-metric, as well as other new metrics are also derived in a unified way.
Pattern formation and mass transfer under stationary solutal Marangoni instability.
Schwarzenberger, Karin; Köllner, Thomas; Linde, Hartmut; Boeck, Thomas; Odenbach, Stefan; Eckert, Kerstin
2014-04-01
According to the seminal theory by Sternling and Scriven, solutal Marangoni convection during mass transfer of surface-active solutes may occur as either oscillatory or stationary instability. With strong support of Manuel G. Velarde, a combined initiative of experimental works, in particular to mention those of Linde, Wierschem and coworkers, and theory has enabled a classification of dominant wave types of the oscillatory mode and their interactions. In this way a rather comprehensive understanding of the nonlinear evolution of the oscillatory instability could be achieved. A comparably advanced state-of-the-art with respect to the stationary counterpart seemed to be out of reach a short time ago. Recent developments on both the numerical and experimental side, in combination with assessing an extensive number of older experiments, now allow one to draw a more unified picture. By reviewing these works, we show that three main building blocks exist during the nonlinear evolution: roll cells, relaxation oscillations and relaxation oscillations waves. What is frequently called interfacial turbulence results from the interaction between these partly coexisting basic patterns which may additionally occur in different hierarchy levels. The second focus of this review lies on the practical importance of such convection patterns concerning their influence on mass transfer characteristics. Particular attention is paid here to the interaction between Marangoni and buoyancy effects which frequently complicates the pattern formation even more. To shed more light on these dependencies, new simulations regarding the limiting case of stabilizing density stratification and vanishing buoyancy are incorporated. PMID:24456800
Some stationary solutions of two-fluid magnetohydrodynamic equations
NASA Astrophysics Data System (ADS)
Avinash, K.
1992-12-01
Some stationary solutions of two-fluid magnetohydrodynamic equations are constructed using generalized helicity invariants. Solutions corresponding to the Z pinch, Bennett pinch, θ pinch, etc., are constructed. The Z-pinch-like solution is identical to Weibel's solution [Phys. Fluids 2, 52 (1959)], while the Bennett-pinch-like solution contains nonuniform axial drifts. By constructing the same solutions from the Vlasov-Maxwell system of equations, it is shown that the results obtained here are consistent with those of Mahajan [Phys. Fluids B 1, 43 (1989)]. Similarly, new θ-pinch-like solutions are constructed and the relation of these to earlier work is discussed.
Stationary and uniformly accelerated states in nonlinear quantum mechanics
NASA Astrophysics Data System (ADS)
Plastino, A. R.; Souza, A. M. C.; Nobre, F. D.; Tsallis, C.
2014-12-01
We consider two kinds of solutions of a recently proposed field theory leading to a nonlinear Schrödinger equation exhibiting solitonlike solutions of the power-law form eqi (k x -w t ), involving the q exponential function naturally arising within nonextensive thermostatistics [eqz≡[1+(1 -q ) z ] 1 /(1 -q ) , with e1z=ez ]. These fundamental solutions behave like free particles, satisfying p =ℏ k , E =ℏ ω , and E =p2/2 m (1 ≤q <2 ) . Here we introduce two additional types of exact, analytical solutions of the aforementioned field theory. As a first step we extend the theory to situations involving a potential energy term, thus going beyond the previous treatment concerning solely the free-particle dynamics. Then we consider both bound, stationary states associated with a confining potential and also time-evolving states corresponding to a linear potential function. These types of solutions might be relevant for physical applications of the present nonlinear generalized Schrödinger equation. In particular, the stationary solution obtained shows an increase in the probability for finding the particle localized around a certain position of the well as one increases q in the interval 1 ≤q <2 , which should be appropriate for physical systems where one finds a low-energy particle localized inside a confining potential.
Landau superfluids as nonequilibrium stationary states
Wreszinski, Walter F.
2015-01-15
We define a superfluid state to be a nonequilibrium stationary state (NESS), which, at zero temperature, satisfies certain metastability conditions, which physically express that there should be a sufficiently small energy-momentum transfer between the particles of the fluid and the surroundings (e.g., pipe). It is shown that two models, the Girardeau model and the Huang-Yang-Luttinger (HYL) model, describe superfluids in this sense and, moreover, that, in the case of the HYL model, the metastability condition is directly related to Nozières’ conjecture that, due to the repulsive interaction, the condensate does not suffer fragmentation into two (or more) parts, thereby assuring its quantum coherence. The models are rigorous examples of NESS in which the system is not finite, but rather a many-body system.
Self-organized stationary states of tokamaks
NASA Astrophysics Data System (ADS)
Jardin, Stephen
2015-11-01
We report here on a nonlinear mechanism that forms and maintains a self-organized stationary (sawtooth free) state in tokamaks. This process was discovered by way of extensive long-time simulations using the M3D-C1 3D extended MHD code in which new physics diagnostics have been added. It is well known that most high-performance modes of tokamak operation undergo ``sawtooth'' cycles, in which the peaking of the toroidal current density triggers a periodic core instability which redistributes the current density. However, certain modes of operation are known, such as the ``hybrid'' mode in DIII-D, ASDEX-U, JT-60U and JET, and the long-lived modes in NSTX and MAST, which do not experience this cycle of instability. Empirically, it is observed that these modes maintain a non-axisymmetric equilibrium which somehow limits the peaking of the toroidal current density. The physical mechanism responsible for this has not previously been understood, but is often referred to as ``flux-pumping,'' in which poloidal flux is redistributed in order to maintain q0 >1. In this talk, we show that in long-time simulations of inductively driven plasmas, a steady-state magnetic equilibrium may be obtained in which the condition q0 >1 is maintained by a dynamo driven by a stationary marginal core interchange mode. This interchange mode, unstable because of the pressure gradient in the ultra-low shear region in the center region, causes a (1,1) perturbation in both the electrostatic potential and the magnetic field, which nonlinearly cause a (0,0) component in the loop voltage that acts to sustain the configuration. This hybrid mode may be a preferred mode of operation for ITER. We present parameter scans that indicate when this sawtooth-free operation can be expected.
Stationary axially symmetric solutions in Brans-Dicke theory
NASA Astrophysics Data System (ADS)
Kirezli, Pınar; Delice, Özgür
2015-11-01
Stationary, axially symmetric Brans-Dicke-Maxwell solutions are reexamined in the framework of the Brans-Dicke (BD) theory. We see that, employing a particular parametrization of the standard axially symmetric metric simplifies the procedure of obtaining the Ernst equations for axially symmetric electrovacuum spacetimes for this theory. This analysis also permits us to construct a two parameter extension in both Jordan and Einstein frames of an old solution generating technique frequently used to construct axially symmetric solutions for BD theory from a seed solution of general relativity. As applications of this technique, several known and new solutions are constructed including a general axially symmetric BD-Maxwell solution of Plebanski-Demianski with vanishing cosmological constant, i.e., the Kinnersley solution and general magnetized Kerr-Newman-type solutions. Some physical properties and the circular motion of test particles for a particular subclass of Kinnersley solution, i.e., a Kerr-Newman-NUT-type solution for BD theory, are also investigated in some detail.
Thermodynamical description of stationary, asymptotically flat solutions with conical singularities
Herdeiro, Carlos; Rebelo, Carmen; Radu, Eugen
2010-05-15
We examine the thermodynamical properties of a number of asymptotically flat, stationary (but not static) solutions having conical singularities, with both connected and nonconnected event horizons, using the thermodynamical description recently proposed in [C. Herdeiro, B. Kleihaus, J. Kunz, and E. Radu, Phys. Rev. D 81, 064013 (2010).]. The examples considered are the double-Kerr solution, the black ring rotating in either S{sup 2} or S{sup 1}, and the black Saturn, where the balance condition is not imposed for the latter two solutions. We show that not only the Bekenstein-Hawking area law is recovered from the thermodynamical description, but also the thermodynamical angular momentum is the Arnowitt-Deser-Misner angular momentum. We also analyze the thermodynamical stability and show that, for all these solutions, either the isothermal moment of inertia or the specific heat at constant angular momentum is negative, at any point in parameter space. Therefore, all these solutions are thermodynamically unstable in the grand canonical ensemble.
Asymptotic stability of stationary states in the wave equation coupled to a nonrelativistic particle
NASA Astrophysics Data System (ADS)
Kopylova, E. A.; Komech, A. I.
2016-01-01
We consider the Hamiltonian system consisting of a scalar wave field and a single particle coupled in a translation invariant manner. The point particle is subjected to an external potential. The stationary solutions of the system are a Coulomb type wave field centered at those particle positions for which the external force vanishes. It is assumed that the charge density satisfies the Wiener condition, which is a version of the "Fermi Golden Rule." We prove that in the large time approximation, any finite energy solution, with the initial state close to the some stable stationary solution, is a sum of this stationary solution and a dispersive wave which is a solution of the free wave equation.
Exponentially Stable Stationary Solutions for Stochastic Evolution Equations and Their Perturbation
Caraballo, Tomas Kloeden, Peter E. Schmalfuss, Bjoern
2004-10-15
We consider the exponential stability of stochastic evolution equations with Lipschitz continuous non-linearities when zero is not a solution for these equations. We prove the existence of anon-trivial stationary solution which is exponentially stable, where the stationary solution is generated by the composition of a random variable and the Wiener shift. We also construct stationary solutions with the stronger property of attracting bounded sets uniformly. The existence of these stationary solutions follows from the theory of random dynamical systems and their attractors. In addition, we prove some perturbation results and formulate conditions for the existence of stationary solutions for semilinear stochastic partial differential equations with Lipschitz continuous non-linearities.
NASA Astrophysics Data System (ADS)
Pástor, P.
2016-04-01
The equations of secular evolution for dust grains in mean motion resonances with a planet are solved for stationary points. This is done including both Poynting-Robertson effect and stellar wind. The solutions are stationary in semimajor axis, eccentricity, and resonant angle, but allow the pericentre to advance. The semimajor axis of stationary solutions can be slightly shifted from the exact resonant value. The periodicity of the stationary solutions in a reference frame orbiting with the planet is analytically proved. The existence of periodic solutions in mean motion resonances means that analytical theory enables for dust particles also infinitely long capture times. The stationary solutions are periodic motions to which the eccentricity asymptotically approaches and around which the libration occurs. Using numerical integration of equation of motion are successfully found initial conditions corresponding to the stationary solutions. Numerically and analytically determined shifts of the semimajor axis form the exact resonance for the stationary solutions are in excellent agreement. The stationary solutions can be plotted by locations of pericenters in the reference frame orbiting with the planet. The pericenters are distributed in the space according to properties of dust particles.
Inferring Microscopic Kinetic Rates from Stationary State Distributions
2015-01-01
We present a principled approach for estimating the matrix of microscopic transition probabilities among states of a Markov process, given only its stationary state population distribution and a single average global kinetic observable. We adapt Maximum Caliber, a variational principle in which the path entropy is maximized over the distribution of all possible trajectories, subject to basic kinetic constraints and some average dynamical observables. We illustrate the method by computing the solvation dynamics of water molecules from molecular dynamics trajectories. PMID:25136269
Discretization of Stationary Solutions of Stochastic Systems Driven by Fractional Brownian Motion
Garrido-Atienza, Maria J. Kloeden, Peter E. Neuenkirch, Andreas
2009-10-15
In this article we study the behavior of dissipative systems with additive fractional noise of any Hurst parameter. Under a one-sided dissipative Lipschitz condition on the drift the continuous stochastic system is shown to have a unique stationary solution, which pathwise attracts all other solutions. The same holds for the discretized stochastic system, if the drift-implicit Euler method is used for the discretization. Moreover, the unique stationary solution of the drift-implicit Euler scheme converges to the unique stationary solution of the original system as the stepsize of the discretization decreases.
On axisymmetric and stationary solutions of the self-gravitating Vlasov system
NASA Astrophysics Data System (ADS)
Ames, Ellery; Andréasson, Håkan; Logg, Anders
2016-08-01
Axisymmetric and stationary solutions are constructed to the Einstein–Vlasov and Vlasov–Poisson systems. These solutions are constructed numerically, using finite element methods and a fixed-point iteration in which the total mass is fixed at each step. A variety of axisymmetric stationary solutions are exhibited, including solutions with toroidal, disk-like, spindle-like, and composite spatial density configurations, as are solutions with non-vanishing net angular momentum. In the case of toroidal solutions, we show for the first time, solutions of the Einstein–Vlasov system which contain ergoregions.
Fluctuations in Stationary Nonequilibrium States of Irreversible Processes
Bertini, L.; De Sole, A.; Gabrielli, D.; Jona-Lasinio, G.; Landim, C.
2001-07-23
We formulate a dynamical fluctuation theory for stationary nonequilibrium states (SNS) which covers situations in a nonlinear hydrodynamic regime and is verified explicitly in stochastic models of interacting particles. In our theory a crucial role is played by the time reversed dynamics. Our results include the modification of the Onsager-Machlup theory in the SNS, a general Hamilton-Jacobi equation for the macroscopic entropy and a nonequilibrium, nonlinear fluctuation dissipation relation valid for a wide class of systems.
Linear stability of stationary solutions of the Vlasov-Poisson system in three dimensions
Batt, J.; Rein, G. . Mathematisches Inst.); Morrison, P.J. )
1993-03-01
Rigorous results on the stability of stationary solutions of the Vlasov-Poisson system are obtained in both the plasma physics and stellar dynamics contexts. It is proven that stationary solutions in the plasma physics (stellar dynamics) case are linearly stable if they are decreasing (increasing) functions of the local, i.e. particle, energy. The main tool in the analysis is the free energy of the system, a conserved quantity. In addition, an appropriate global existence result is proven for the linearized Vlasov-Poisson system and the existence of stationary solutions that satisfy the above stability condition is established.
Maximum entropy principle for stationary states underpinned by stochastic thermodynamics.
Ford, Ian J
2015-11-01
The selection of an equilibrium state by maximizing the entropy of a system, subject to certain constraints, is often powerfully motivated as an exercise in logical inference, a procedure where conclusions are reached on the basis of incomplete information. But such a framework can be more compelling if it is underpinned by dynamical arguments, and we show how this can be provided by stochastic thermodynamics, where an explicit link is made between the production of entropy and the stochastic dynamics of a system coupled to an environment. The separation of entropy production into three components allows us to select a stationary state by maximizing the change, averaged over all realizations of the motion, in the principal relaxational or nonadiabatic component, equivalent to requiring that this contribution to the entropy production should become time independent for all realizations. We show that this recovers the usual equilibrium probability density function (pdf) for a conservative system in an isothermal environment, as well as the stationary nonequilibrium pdf for a particle confined to a potential under nonisothermal conditions, and a particle subject to a constant nonconservative force under isothermal conditions. The two remaining components of entropy production account for a recently discussed thermodynamic anomaly between over- and underdamped treatments of the dynamics in the nonisothermal stationary state. PMID:26651681
Critical dynamic approach to stationary states in complex systems
NASA Astrophysics Data System (ADS)
Rozenfeld, A. F.; Laneri, K.; Albano, E. V.
2007-04-01
A dynamic scaling Ansatz for the approach to stationary states in complex systems is proposed and tested by means of extensive simulations applied to both the Bak-Sneppen (BS) model, which exhibits robust Self-Organised Critical (SOC) behaviour, and the Game of Life (GOL) of J. Conway, whose critical behaviour is under debate. Considering the dynamic scaling behaviour of the density of sites (ρ(t)), it is shown that i) by starting the dynamic measurements with configurations such that ρ(t=0) →0, one observes an initial increase of the density with exponents θ= 0.12(2) and θ= 0.11(2) for the BS and GOL models, respectively; ii) by using initial configurations with ρ(t=0) →1, the density decays with exponents δ= 0.47(2) and δ= 0.28(2) for the BS and GOL models, respectively. It is also shown that the temporal autocorrelation decays with exponents Ca = 0.35(2) (Ca = 0.35(5)) for the BS (GOL) model. By using these dynamically determined critical exponents and suitable scaling relationships, we also obtain the dynamic exponents z = 2.10(5) (z = 2.10(5)) for the BS (GOL) model. Based on this evidence we conclude that the dynamic approach to stationary states of the investigated models can be described by suitable power-law functions of time with well-defined exponents.
Deterministic creation of stationary entangled states by dissipation
Alharbi, A. F.; Ficek, Z.
2010-11-15
We propose a practical physical system for creation of stationary entanglement by dissipation without employing environmental engineering techniques. The system proposed is composed of two perfectly distinguishable atoms, through their significantly different transition frequencies, with only one atom addressed by an external laser field. We show that the arrangement would easily be realized in practice by trapping the atoms at a distance equal to the quarter-wavelength of a standing-wave laser field and locating one of the atoms at a node and the other at the successive antinode of the wave. The undesirable dipole-dipole interaction between the atoms, which could be large at this small distance, is adjusted to zero by a specific initial preparation of the atoms or by a specific polarization of the atomic dipole moments. Following this arrangement, we show that the dissipative relaxation can create a stationary entanglement on demand by tuning the Rabi frequency of the laser field to the difference between the atomic transition frequencies. The laser field dresses the atom and we identify that the entangled state occurs when the frequency of one of the Rabi sidebands of the driven atom tunes to the frequency of the undriven atom. It is also found that this system behaves as a cascade open system where the fluorescence from the dressed atom drives the other atom with no feedback.
Stationary states of extended nonlinear Schrödinger equation with a source
NASA Astrophysics Data System (ADS)
Borich, M. A.; Smagin, V. V.; Tankeev, A. P.
2007-02-01
Structure of nonlinear stationary states of the extended nonlinear Schrödinger equation (ENSE) with a source has been analyzed with allowance for both third-order and nonlinearity dispersion. A new class of particular solutions (solitary waves) of the ENSe has been obtained. The scenario of the destruction of these states under the effect of an external perturbation has been investigated analytically and numerically. The results obtained can be used to interpret experimental data on the weakly nonlinear dynamics of the magnetostatic envelope in heterophase ferromagnet-insulator-metal, metal-insulator-ferromagnet-insulator-metal, and other similar structures and upon the simulation of nonlinear processes in optical systems.
Time and 'angular' dependent backgrounds from stationary axisymmetric solutions
Obregon, Octavio; Quevedo, Hernando; Ryan, Michael P.
2004-09-15
Backgrounds depending on time and on angular variable, namely, polarized and unpolarized S{sup 1}xS{sup 2} Gowdy models, are generated as the sector inside the horizons of the manifold corresponding to axisymmetric solutions. As is known, an analytical continuation of ordinary D-branes, iD-branes allow one to find S-brane solutions. Simple models have been constructed by means of analytic continuation of the Schwarzschild and the Kerr metrics. The possibility of studying the i-Gowdy models obtained here is outlined with an eye toward seeing if they could represent some kind of generalized S-branes depending not only on time but also on an angular variable.
NASA Astrophysics Data System (ADS)
Gariel, J.; Marcilhacy, G.; Santos, N. O.
2008-02-01
We extend the method of separation of variables, studied by Léauté and Marcilhacy [Ann. Inst. Henri Poincare, Sect. A 331, 363 (1979)], to obtain transcendent solutions of the field equations for stationary axisymmetric systems. These solutions depend on transcendent functions satisfying a third order differential equation. For some solutions this equation satisfies the necessary conditions, but not sufficient, to have fixed critical points.
Grach, V. S. Garasev, M. A.
2015-07-15
We consider the interaction of a isolated conducting sphere with a collisional weakly ionized plasma in an external field. We assume that the plasma consists of two species of ions neglecting of electrons. We take into account charging of the sphere due to sedimentation of plasma ions on it, the field of the sphere charge and the space charge, as well as recombination and molecular diffusion. The nonstationary problem of interaction of the sphere with the surrounding plasma is solved numerically. The temporal dynamics of the sphere charge and plasma perturbations is analyzed, as well as the properties of the stationary state. It is shown that the duration of transient period is determined by the recombination time and by the reverse conductivity of ions. The temporal dynamics of the sphere charge and plasma perturbations is determined by the intensity of recombination processes relative to the influence of the space charge field and diffusion. The stationary absolute value of the sphere charge increases linearly with the external electric field, decreases with the relative intensity of recombination processes and increases in the presence of substantial diffusion. The scales of the perturbed region in the plasma are determined by the radius of the sphere, the external field, the effect of diffusion, and the relative intensity of recombination processes. In the limiting case of the absence of molecular diffusion and a strong external field, the properties of the stationary state coincide with those obtained earlier as a result of approximate solution.
NASA Astrophysics Data System (ADS)
Tod, Paul
2007-07-01
Following the technique of Müller zum Hagen (Proc. Camb. Phil. Soc. 67: 415-421, 1970) we show that strictly static and strictly stationary solutions of the Einstein-Maxwell equations are analytic in harmonic coordinates. This holds whether or not the Maxwell field inherits the symmetry.
GPELab, a Matlab toolbox to solve Gross-Pitaevskii equations I: Computation of stationary solutions
NASA Astrophysics Data System (ADS)
Antoine, Xavier; Duboscq, Romain
2014-11-01
This paper presents GPELab (Gross-Pitaevskii Equation Laboratory), an advanced easy-to-use and flexible Matlab toolbox for numerically simulating many complex physics situations related to Bose-Einstein condensation. The model equation that GPELab solves is the Gross-Pitaevskii equation. The aim of this first part is to present the physical problems and the robust and accurate numerical schemes that are implemented for computing stationary solutions, to show a few computational examples and to explain how the basic GPELab functions work. Problems that can be solved include: 1d, 2d and 3d situations, general potentials, large classes of local and nonlocal nonlinearities, multi-components problems, and fast rotating gases. The toolbox is developed in such a way that other physics applications that require the numerical solution of general Schrödinger-type equations can be considered. Catalogue identifier: AETU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AETU_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 26 552 No. of bytes in distributed program, including test data, etc.: 611 289 Distribution format: tar.gz Programming language: Matlab. Computer: PC, Mac. Operating system: Windows, Mac OS, Linux. Has the code been vectorized or parallelized?: Yes RAM: 4000 Megabytes Classification: 2.7, 4.6, 7.7. Nature of problem: Computing stationary solutions for a class of systems (multi-components) of Gross-Pitaevskii equations in 1d, 2d and 3d. This program is particularly well designed for the computation of ground states of Bose-Einstein condensates as well as dynamics. Solution method: We use the imaginary-time method with a Semi-Implicit Backward Euler scheme, a pseudo-spectral approximation and a Krylov subspace method. Running time: From a few minutes
NASA Astrophysics Data System (ADS)
Garcia-Diaz, Alberto A.; Gutierrez-Cano, Gustavo
It is established that the conformal type D electrovacuum stationary axisymmetric Carter class of metrics splits into three families of solutions: the Plebański-Demiański family, the Carter-Plebański spacetimes, and the trigonometric-hyperbolic conformal class. This last class, via coordinate transformations, can be brought to the C-P form. These metrics admit an Abelian group of motions G2 with commuting stationary and angular Killing vectors, are of Petrov type D; the null eigenvectors of the general electromagnetic field coincide with the directions of the Debever null vectors of Weyl curvature tensor. These solutions exhibit, for certain ranges of the coordinate variables, a black hole behavior; a "ring" singularity similar to the one of the Kerr metric is present. The limiting transition of these solutions leads to the Kerr-Newman black hole solution as a subbranch.
Mixed addenda polyoxometalate "solutions" for stationary energy storage.
Pratt, Harry D; Anderson, Travis M
2013-11-28
A series of redox flow batteries utilizing mixed addenda (vanadium and tungsten), phosphorus-based polyoxometalates (A-α-PV3W9O40(6-), B-α-PV3W9O40(6-), and P2V3W15O62(9-)) were prepared and tested. Cyclic voltammetry and bulk electrolysis experiments on the Keggin compounds (A-α-PV3W9O40(6-) and B-α-PV3W9O40(6-)) established that the vanadium centers of these compounds could be used as the positive electrode (PV(IV)3W(VI)9O40(9-)/PV(V)3W(VI)9O40(6-)), and the tungsten centers could be used as the negative electrode (PV(IV)3W(VI)9O40(9-)/PV(IV)3W(V)3W(VI)6O40(12-)) since these electrochemical processes are separated by about 1 V. The results showed that A-α-PV3W9O40(6-) (where A indicates adjacent, corner-sharing vanadium atoms) had coulombic efficiencies (charge in divided by charge out) above 80%, while the coulombic efficiency of B-α-PV3W9O40(6-) (where B indicates adjacent edge-sharing vanadium atoms) fluctuated between 50% and 70% during cycling. The electrochemical yield, a measurement of the actual charge or discharge observed in comparison with the theoretical charge, was between 40% and 50% for A-α-PV3W9O40(6-), and (31)P NMR showed small amounts of PV2W10O40(5-) and PVW11O40(4-) formed with cycling. The electrochemical yield for B-α-PV3W9O40(6-) decreased from 90% to around 60% due to precipitation of the compound on the electrode, but there were no decomposition products detected in the solution by (31)P NMR, and infrared data on the electrode suggested that the cluster remained intact. Testing of P2V3W15O62(9-) (Wells-Dawson structure) suggested higher charge density clusters were not as suitable as the Keggin structures for a redox flow battery due to the poor stability and inaccessibility of the highly reduced materials. PMID:24042471
NASA Astrophysics Data System (ADS)
Pástor, P.
2016-07-01
The equations of secular evolution for dust grains in mean motion resonances with a planet are solved for stationary points. Non-gravitational effects caused by stellar radiation (the Poynting-Robertson effect and the stellar wind) are taken into account. The solutions are stationary in the semimajor axis, eccentricity and resonant angle, but allow the pericentre to advance. The semimajor axis of stationary solutions can be slightly shifted from the exact resonant value. The periodicity of the stationary solutions in a reference frame orbiting with the planet is proved analytically. The existence of periodic solutions in mean motion resonances means that analytical theory enables infinitely long capture times for dust particles. The stationary solutions are periodic motions to which the eccentricity asymptotically approaches and around which the libration occurs. Initial conditions corresponding to the stationary solutions are successfully found by numerically integrating the equation of motion. Numerically and analytically determined shifts of the semimajor axis from the exact resonance for the stationary solutions are in excellent agreement. The stationary solutions can be plotted by the locations of pericentres in the reference frame orbiting with the planet. The pericentres are distributed in space according to the properties of the dust particles.
Linear Augmentation for Stabilizing Stationary Solutions: Potential Pitfalls and Their Application
Karnatak, Rajat
2015-01-01
Linear augmentation has recently been shown to be effective in targeting desired stationary solutions, suppressing bistablity, in regulating the dynamics of drive response systems and in controlling the dynamics of hidden attractors. The simplicity of the procedure is the main highlight of this scheme but questions related to its general applicability still need to be addressed. Focusing on the issue of targeting stationary solutions, this work demonstrates instances where the scheme fails to stabilize the required solutions and leads to other complicated dynamical scenarios. Examples from conservative as well as dissipative systems are presented in this regard and important applications in dissipative predator—prey systems are discussed, which include preventative measures to avoid potentially catastrophic dynamical transitions in these systems. PMID:26544879
Convergence rates to stationary solutions of a gas-liquid model with external forces
NASA Astrophysics Data System (ADS)
Fan, Long; Liu, Qingqing; Zhu, Changjiang
2012-10-01
In this paper, we study the asymptotic behaviour of solutions to a gas-liquid model with external forces. Under some suitable assumptions on the initial data, if γ > 1 and \\theta\\in(0,\\frac{\\gamma}{2}]\\cap(0,\\gamma-1]\\cap(0,1-\\alpha\\gamma] , we prove the weak solution (cQ (x, t), u(x, t)) behaviour asymptotically to the stationary one by adapting and modifying the technique of weighted estimates. In addition, if \\theta\\in(0,\\frac{\\gamma}{2}]\\cap(0,\\gamma-1)\\cap(0,1-\\alpha\\gamma] , following the same idea used in Zhang and Fang (2006 Arch. Ration. Mech. Anal. 182 223-53), we estimate the stabilization rate of the solution as time tends to infinity in the sense of L∞ norm.
Overview of commercialization of stationary fuel cell power plants in the United States
Hooie, D.T.; Williams, M.C.
1995-07-01
In this paper, DOE`s efforts to assist private sector organizations to develop and commercialize stationary fuel cell power plants in the United States are discussed. The paper also provides a snapshot of the status of stationary power fuel cell development occurring in the US, addressing all fuel cell types. This paper discusses general characteristics, system configurations, and status of test units and demonstration projects. The US DOE, Morgantown Energy Technology Center is the lead center for implementing DOE`s program for fuel cells for stationary power.
Goedbloed, J. P.
2009-12-15
A new method of systematically constructing the full structure of the complex magnetohydrodynamic spectra of stationary flows is presented. It is based on the self-adjointness of the generalized force operator G and the Doppler-Coriolis shift operator U, and the associated quadratic forms for the normalized energy W and the normalized Doppler-Coriolis shift V, which may be constructed for all complex values of omega if the original eigenvalue problem is converted into a one-sided boundary value problem. This turns W into a complex expression, while V remains real. Whereas the solution path P{sub s} of stable modes is just the real axis, the solution path P{sub u} of unstable modes in the complex omega plane is found by requiring that the solution-averaged Doppler-Coriolis shifted real part of the frequency vanishes, sigma-V[xi(omega)]=0, or that the energy is real, Im W[xi(omega)]=0. The location of the eigenvalues on these solution paths is determined by two quadratic forms, which may straightforwardly be evaluated in any of the finite element spectral codes in existence. A new oscillation theorem is proved about the monotonicity of complex eigenvalues for one-dimensional systems. Instead of counting internal nodes of the real displacement vector xi (as in static plasmas), it is based on counting the zeros of the alternating ratio, or alternator, Rident toxi/PI of the boundary values of the complex functions xi and the total pressure perturbation PI, which is real on the solution path. This finally provides the generalization of the basic structural properties of the magnetohydrodynamic spectrum of static plasmas, which has been known for a long time, to stationary plasmas.
NASA Astrophysics Data System (ADS)
Zuo, Wenjie; Jiang, Daqing
2016-07-01
In this paper, we investigate the dynamics of the stochastic autonomous and non-autonomous predator-prey systems with nonlinear predator harvesting respectively. For the autonomous system, we first give the existence of the global positive solution. Then, in the case of persistence, we prove that there exists a unique stationary distribution and it has ergodicity by constructing a suitable Lyapunov function. The result shows that, the relatively weaker white noise will strengthen the stability of the system, but the stronger white noise will result in the extinction of one or two species. Particularly, for the non-autonomous periodic system, we show that there exists at least one nontrivial positive periodic solution according to the theory of Khasminskii. Finally, numerical simulations illustrate our theoretical results.
Ferrofluid patterns in Hele-Shaw cells: Exact, stable, stationary shape solutions
NASA Astrophysics Data System (ADS)
Lira, Sérgio A.; Miranda, José A.
2016-01-01
We investigate a quasi-two-dimensional system composed of an initially circular ferrofluid droplet surrounded by a nonmagnetic fluid of higher density. These immiscible fluids flow in a rotating Hele-Shaw cell, under the influence of an in-plane radial magnetic field. We focus on the situation in which destabilizing bulk magnetic field effects are balanced by stabilizing centrifugal forces. In this framing, we consider the interplay of capillary and magnetic normal traction effects in determining the fluid-fluid interface morphology. By employing a vortex-sheet formalism, we have been able to find a family of exact stationary N -fold polygonal shape solutions for the interface. A weakly nonlinear theory is then used to verify that such exact interfacial solutions are in fact stable.
Ferrofluid patterns in Hele-Shaw cells: Exact, stable, stationary shape solutions.
Lira, Sérgio A; Miranda, José A
2016-01-01
We investigate a quasi-two-dimensional system composed of an initially circular ferrofluid droplet surrounded by a nonmagnetic fluid of higher density. These immiscible fluids flow in a rotating Hele-Shaw cell, under the influence of an in-plane radial magnetic field. We focus on the situation in which destabilizing bulk magnetic field effects are balanced by stabilizing centrifugal forces. In this framing, we consider the interplay of capillary and magnetic normal traction effects in determining the fluid-fluid interface morphology. By employing a vortex-sheet formalism, we have been able to find a family of exact stationary N-fold polygonal shape solutions for the interface. A weakly nonlinear theory is then used to verify that such exact interfacial solutions are in fact stable. PMID:26871176
Irreducible Decompositions and Stationary States of Quantum Channels
NASA Astrophysics Data System (ADS)
Carbone, Raffaella; Pautrat, Yan
2016-06-01
For a quantum channel (completely positive, trace-preserving map), we prove a generalization to the infinite-dimensional case of a result by Baumgartner and Narnhofer [3]: this result is, in a probabilistic language, a decomposition of a general quantum channel into its irreducible recurrent components. More precisely, we prove that the positive recurrent subspace (i.e. the space supporting the invariant states) can be decomposed as the direct sum of supports of extremal invariant states; this decomposition is not unique, in general, but we can determine all the possible decompositions. This allows us to describe the full structure of invariant states.
Hong Xinguo; Hao Quan
2009-01-15
In this paper, we report a method of precise in situ x-ray scattering measurements on protein solutions using small stationary sample cells. Although reduction in the radiation damage induced by intense synchrotron radiation sources is indispensable for the correct interpretation of scattering data, there is still a lack of effective methods to overcome radiation-induced aggregation and extract scattering profiles free from chemical or structural damage. It is found that radiation-induced aggregation mainly begins on the surface of the sample cell and grows along the beam path; the diameter of the damaged region is comparable to the x-ray beam size. Radiation-induced aggregation can be effectively avoided by using a two-dimensional scan (2D mode), with an interval as small as 1.5 times the beam size, at low temperature (e.g., 4 deg. C). A radiation sensitive protein, bovine hemoglobin, was used to test the method. A standard deviation of less than 5% in the small angle region was observed from a series of nine spectra recorded in 2D mode, in contrast to the intensity variation seen using the conventional stationary technique, which can exceed 100%. Wide-angle x-ray scattering data were collected at a standard macromolecular diffraction station using the same data collection protocol and showed a good signal/noise ratio (better than the reported data on the same protein using a flow cell). The results indicate that this method is an effective approach for obtaining precise measurements of protein solution scattering.
NASA Astrophysics Data System (ADS)
Wu, Junde
2016-04-01
In this paper we study a free boundary problem modeling tumor growth. The model consists of two elliptic equations describing nutrient diffusion and pressure distribution within tumors, respectively, and a first-order partial differential equation governing the free boundary, on which a Gibbs-Thomson relation is taken into account. We first show that the problem may have none, one or two radial stationary solutions depending on model parameters. Then by bifurcation analysis we show that there exist infinite many branches of non-radial stationary solutions bifurcating from given radial stationary solution. The result implies that cell-to-cell adhesiveness is the key parameter which plays a crucial role on tumor invasion.
Dadinova, Liubov A.; Shtykova, Eleonora V.; Konarev, Petr V.; Rodina, Elena V.; Snalina, Natalia E.; Vorobyeva, Natalia N.; Kurilova, Svetlana A.; Nazarova, Tatyana I.; Jeffries, Cy M.; Svergun, Dmitri I.
2016-01-01
The structural analyses of four metabolic enzymes that maintain and regulate the stationary growth phase of Escherichia coli have been performed primarily drawing on the results obtained from solution small angle X-ray scattering (SAXS) and other structural techniques. The proteins are (i) class I fructose-1,6-bisphosphate aldolase (FbaB); (ii) inorganic pyrophosphatase (PPase); (iii) 5-keto-4-deoxyuronate isomerase (KduI); and (iv) glutamate decarboxylase (GadA). The enzyme FbaB, that until now had an unknown structure, is predicted to fold into a TIM-barrel motif that form globular protomers which SAXS experiments show associate into decameric assemblies. In agreement with previously reported crystal structures, PPase forms hexamers in solution that are similar to the previously reported X-ray crystal structure. Both KduI and GadA that are responsible for carbohydrate (pectin) metabolism and acid stress responses, respectively, form polydisperse mixtures consisting of different oligomeric states. Overall the SAXS experiments yield additional insights into shape and organization of these metabolic enzymes and further demonstrate the utility of hybrid methods, i.e., solution SAXS combined with X-ray crystallography, bioinformatics and predictive 3D-structural modeling, as tools to enrich structural studies. The results highlight the structural complexity that the protein components of metabolic networks may adopt which cannot be fully captured using individual structural biology techniques. PMID:27227414
Dadinova, Liubov A; Shtykova, Eleonora V; Konarev, Petr V; Rodina, Elena V; Snalina, Natalia E; Vorobyeva, Natalia N; Kurilova, Svetlana A; Nazarova, Tatyana I; Jeffries, Cy M; Svergun, Dmitri I
2016-01-01
The structural analyses of four metabolic enzymes that maintain and regulate the stationary growth phase of Escherichia coli have been performed primarily drawing on the results obtained from solution small angle X-ray scattering (SAXS) and other structural techniques. The proteins are (i) class I fructose-1,6-bisphosphate aldolase (FbaB); (ii) inorganic pyrophosphatase (PPase); (iii) 5-keto-4-deoxyuronate isomerase (KduI); and (iv) glutamate decarboxylase (GadA). The enzyme FbaB, that until now had an unknown structure, is predicted to fold into a TIM-barrel motif that form globular protomers which SAXS experiments show associate into decameric assemblies. In agreement with previously reported crystal structures, PPase forms hexamers in solution that are similar to the previously reported X-ray crystal structure. Both KduI and GadA that are responsible for carbohydrate (pectin) metabolism and acid stress responses, respectively, form polydisperse mixtures consisting of different oligomeric states. Overall the SAXS experiments yield additional insights into shape and organization of these metabolic enzymes and further demonstrate the utility of hybrid methods, i.e., solution SAXS combined with X-ray crystallography, bioinformatics and predictive 3D-structural modeling, as tools to enrich structural studies. The results highlight the structural complexity that the protein components of metabolic networks may adopt which cannot be fully captured using individual structural biology techniques. PMID:27227414
Quasi-stationary states and a classification of the range of pair interactions
Gabrielli, A.; Joyce, M.; Marcos, B.
2011-03-24
Systems of long-range interacting particles present typically 'quasi-stationary' states (QSS). Investigating their lifetime for a generic pair interaction V(r{yields}{infinity}){approx}1/r{sup {gamma}} we give a classification of the range of the interactions according to the dynamical properties of the system.
Lévy flights and nonhomogenous memory effects: Relaxation to a stationary state.
Srokowski, Tomasz
2015-07-01
The non-Markovian stochastic dynamics involving Lévy flights and a potential in the form of a harmonic and nonlinear oscillator is discussed. The subordination technique is applied and the memory effects, which are nonhomogeneous, are taken into account by a position-dependent subordinator. In the nonlinear case, the asymptotic stationary states are found. The relaxation pattern to the stationary state is derived for the quadratic potential: the density decays like a linear combination of the Mittag-Leffler functions. It is demonstrated that in the latter case the density distribution satisfies a fractional Fokker-Planck equation. The densities for the nonlinear oscillator reveal a complex picture, qualitatively dependent on the potential strength, and the relaxation pattern is exponential at large time. PMID:26274142
The stationary resonance fluorescence of a two-level atom in a cat-state field
NASA Astrophysics Data System (ADS)
Tomilin, V. A.; Il'ichov, L. V.
2016-09-01
We investigate the resonance fluorescence of a two-level atom placed in non-classical field which is a superposition of Glauber coherent states. The source of this superposition known under the common name of 'Schrödinger cat'-states is explicitly incorporated into the model. This let us to explore the stationary regime. In the strong (multiphoton) field limit the steady-state of the atom+photons system is found. We evaluated the spectrum of the resonance fluorescence. It appears to be one-component in contrast to the case with the classical external field.
McKenzie, J. F.; Doyle, T. B.; Rajah, S. S.
2012-11-15
The theory of fully nonlinear stationary electrostatic ion cyclotron waves is further developed. The existence of two fundamental constants of motion; namely, momentum flux density parallel to the background magnetic field and energy density, facilitates the reduction of the wave structure equation to a first order differential equation. For subsonic waves propagating sufficiently obliquely to the magnetic field, soliton solutions can be constructed. Importantly, analytic expressions for the amplitude of the soliton show that it increases with decreasing wave Mach number and with increasing obliquity to the magnetic field. In the subsonic, quasi-parallel case, periodic waves exist whose compressive and rarefactive amplitudes are asymmetric about the 'initial' point. A critical 'driver' field exists that gives rise to a soliton-like structure which corresponds to infinite wavelength. If the wave speed is supersonic, periodic waves may also be constructed. The aforementioned asymmetry in the waveform arises from the flow being driven towards the local sonic point in the compressive phase and away from it in the rarefactive phase. As the initial driver field approaches the critical value, the end point of the compressive phase becomes sonic and the waveform develops a wedge shape. This feature and the amplitudes of the compressive and rarefactive portions of the periodic waves are illustrated through new analytic expressions that follow from the equilibrium points of a wave structure equation which includes a driver field. These expressions are illustrated with figures that illuminate the nature of the solitons. The presently described wedge-shaped waveforms also occur in water waves, for similar 'transonic' reasons, when a Coriolis force is included.
Aljhni, Rania; Andre, Claire; Lethier, Lydie; Guillaume, Yves Claude
2015-11-01
A carbon nanotube (CNT) stationary phase was used for the first time to study the β-cyclodextrin (β-CD) solute complexation mechanism using high performance liquid chromatography (HPLC). For this, the β-CD was added at various concentrations in the mobile phase and the effect of column temperature was studied on both the retention of a series of aniline and benzoic acid derivatives with the CNT stationary phase and their complexation mechanism with β-CD. A decrease in the solute retention factor was observed for all the studied molecules without change in the retention order. The apparent formation constant KF of the inclusion complex β-CD/solute was determined at various temperatures. Our results showed that the interaction of β-CD with both the mobile phase and the stationary phase interfered in the complex formation. The enthalpy and entropy of the complex formation (ΔHF and ΔSF) between the solute molecule and CD were determined using a thermodynamic approach. Negative enthalpies and entropies indicated that the inclusion process of the studied molecule in the CD cavity was enthalpically driven and that the hydrogen bonds between carboxylic or aniline groups and the functional groups on the β-CD rim play an important role in the complex formation. PMID:26452814
Attractor nonequilibrium stationary states in perturbed long-range interacting systems
NASA Astrophysics Data System (ADS)
Joyce, Michael; Morand, Jules; Viot, Pascal
2016-05-01
Isolated long-range interacting particle systems appear generically to relax to nonequilibrium states ("quasistationary states" or QSSs) which are stationary in the thermodynamic limit. A fundamental open question concerns the "robustness" of these states when the system is not isolated. In this paper we explore, using both analytical and numerical approaches to a paradigmatic one-dimensional model, the effect of a simple class of perturbations. We call them "internal local perturbations" in that the particle energies are perturbed at collisions in a way which depends only on the local properties. Our central finding is that the effect of the perturbations is to drive all the very different QSSs we consider towards a unique QSS. The latter is thus independent of the initial conditions of the system, but determined instead by both the long-range forces and the details of the perturbations applied. Thus in the presence of such a perturbation the long-range system evolves to a unique nonequilibrium stationary state, completely different from its state in absence of the perturbation, and it remains in this state when the perturbation is removed. We argue that this result may be generic for long-range interacting systems subject to perturbations which are dependent on the local properties (e.g., spatial density or velocity distribution) of the system itself.
Stationary bound states of massless scalar fields around black holes and black hole analogues
NASA Astrophysics Data System (ADS)
Benone, Carolina L.; Crispino, Luís C. B.; Herdeiro, Carlos A. R.; Radu, Eugen
2015-06-01
We discuss stationary bound states, a.k.a. clouds, for a massless test scalar field around Kerr black holes (BHs) and spinning acoustic BH analogues. In view of the absence of a mass term, the trapping is achieved via enclosing the BH — scalar field system in a cavity and imposing Dirichlet or Neumann boundary conditions. We discuss the variation of these bounds states with the discrete parameters that label them, as well as their spatial distribution, complementing results in our previous work [C. L. Benone, L. C. B. Crispino, C. Herdeiro and E. Radu, Phys. Rev. D91 (2015) 104038].
NASA Astrophysics Data System (ADS)
Ribeiro, M. S.; Nobre, F. D.; Curado, E. M. F.
2012-12-01
By comparing numerical and analytical results, it is shown that a system of interacting particles under overdamped motion is very well described by a nonlinear Fokker-Planck equation, which can be associated with nonextensive statistical mechanics. The particle-particle interactions considered are repulsive, motivated by three different physical situations: (i) modified Bessel function, commonly used in vortex-vortex interactions, relevant for the flux-front penetration in disordered type-II superconductors; (ii) Yukawa-like forces, useful for charged particles in plasma, or colloidal suspensions; (iii) derived from a Gaussian potential, common in complex fluids, like polymer chains dispersed in a solvent. Moreover, the system is subjected to a general confining potential, φ( x) = ( α| x| z )/ z ( α > 0 , z > 1), so that a stationary state is reached after a sufficiently long time. Recent numerical and analytical investigations, considering interactions of type (i) and a harmonic confining potential ( z = 2), have shown strong evidence that a q-Gaussian distribution, P( x,t), with q = 0, describes appropriately the particle positions during their time evolution, as well as in their stationary state. Herein we reinforce further the connection with nonextensive statistical mechanics, by presenting numerical evidence showing that: (a) in the case z = 2, different particle-particle interactions only modify the diffusion parameter D of the nonlinear Fokker-Planck equation; (b) for z ≠ 2, all cases investigated fit well the analytical stationary solution P st( x), given in terms of a q-exponential (with the same index q = 0) of the general external potential φ( x). In this later case, we propose an approximate time-dependent P( x,t) (not known analytically for z ≠ 2), which is in very good agreement with the simulations for a large range of times, including the approach to the stationary state. The present work suggests that a wide variety of physical phenomena
NASA Astrophysics Data System (ADS)
Wang, Deng-Shan; Han, Wei; Shi, Yuren; Li, Zaidong; Liu, Wu-Ming
2016-07-01
The spin-1 Bose-Einstein condensates trapped in a standing light wave can be described by three coupled Gross-Pitaevskii equations with a periodic potential. In this paper, nine families of stationary solutions without phase structures in the form of Jacobi elliptic functions are proposed, and their stabilities are analyzed by both linear stability analysis and dynamical evolutions. Taking the ferromagnetic 87Rb atoms and antiferromagnetic (polar) 23Na atoms as examples, we investigate the stability regions of the nine stationary solutions, which are given in term of elliptic modulus k. It is shown that for the same stationary solution the stability regions of condensates with antiferromagnetic (polar) spin-dependent interactions are larger than that of the condensates with ferromagnetic ones. The dn-dn-dn stationary solution is the most stable solution among the nine families of stationary solutions. Moreover, in the same standing light wave, the spin-1 Bose-Einstein condensates are more stable than the scalar Bose-Einstein condensate.
NASA Astrophysics Data System (ADS)
Wan, Ling; Wang, Tao; Zou, Qingyang
2016-04-01
We investigate the large-time behavior of solutions to an outflow problem of the compressible Navier-Stokes equations for viscous and heat-conducting ideal polytropic gases in the half line. The non-degenerate stationary solution is shown to be asymptotically stable under large initial perturbation with no restriction on the adiabatic exponent, provided that the boundary strength is sufficiently small. The proofs are based on the nonlinear energy estimates and the crucial step is to obtain positive lower and upper bounds of the density and the temperature uniformly in time and space.
Stability and hierarchy of quasi-stationary states: financial markets as an example
NASA Astrophysics Data System (ADS)
Stepanov, Yuriy; Rinn, Philip; Guhr, Thomas; Peinke, Joachim; Schäfer, Rudi
2015-08-01
We combine geometric data analysis and stochastic modeling to describe the collective dynamics of complex systems. As an example we apply this approach to financial data and focus on the non-stationarity of the market correlation structure. We identify the dominating variable and extract its explicit stochastic model. This allows us to establish a connection between its time evolution and known historical events on the market. We discuss the dynamics, the stability and the hierarchy of the recently proposed quasi-stationary market states.
Stationary state Kohn-Sham Theory: Modern algorithms breathe new life into an old theory
NASA Astrophysics Data System (ADS)
Gunceler, Deniz; Sundararaman, Ravishankar; Arias, T. A.
2014-03-01
In this talk, we will discuss stationary-state Kohn-Sham theory, an old (Phys. Rev. B 31, 6264-6272) but largely ignored idea that is recently undergoing revival. It is based on an in-principle exact scheme in which excited states are computed as the stationary states of the Hohenberg-Kohn functional. We will discuss the objections of Gaudoin and Burke (Phys. Rev. Lett. 93, 17), and also describe the computational difficulties which prevented this theory from becoming popular in the past, and present new algorithms for computing the predictions of this theory. The resulting technique has inherent computational advantages over TDDFT and GW, and results using semilocal functionals show great promise for molecules. However, the method as implemented exhibits large errors for solids. In this talk, we shall show that the origin of this behaviour is related to the fact that different errors dominate the solid and molecular cases, and we shall discuss prospects for improvement of the theory in the future.
Peyrin, E; Guillaume, Y C; Morin, N; Guinchard, C
1998-07-15
In a chromatographic system using human serum albumin (HSA) as a stationary phase, D,L dansyl amino acids as solutes, and sucrose as a mobile-phase modifier, a study on the surface tension effect of sugar on compound retention was carried out by varying the salting-out agent concentration c and the column temperature T. The thermodynamic parameters for solute transfer from the mobile to the stationary phase were determined from linear van't Hoff plots. An enthalpy-entropy compensation study revealed that the type of interaction between solute and HSA was independent of the molecular structure of the dansyl amino acids and the mobile-phase composition. An analysis of the experimental variations in the retention factor and the enantioselectivity values with c was performed using a theoretical model. It was shown that the decrease in solute retention accompanying the sucrose concentration increase was principally governed by a structural rearrangement of the binding cavity due to the increased surface tension effects. The cavity apolar residues were assumed to fold out of contact with the medium in order to reduce the surface area accessible to sucrose molecules, thus implying a restriction of the curvature radius of the cavity. Such behavior caused a decrease in the hydrophobic interaction for ligand binding on HSA explaining the observed thermodynamic parameter trends over the sucrose concentration range. PMID:9684542
Dasgupta, B.; Burrows, R.; Zank, G. P.; Webb, G. M.
2006-08-15
In this work we investigate how reflected particles modify the Rankine-Hugoniot (RH) relations in a simple hydrodynamical framework. It is assumed that the ions are specularly reflected by the cross-shock potential. For simplicity, an exactly perpendicular shock is assumed, thus other reflection mechanisms, such as magnetic mirroring, can be neglected. Momentum and energy terms are introduced to model reflected particles at the shock and the RH conditions are examined using a geometrical entropy condition to distinguish the physically relevant states. Although such shocks have some common features with combustion shocks within a narrow range of reflection parameters, for a wide range of reflection parameters, particularly for highly oblique shocks, Chapman-Jouguet solutions do not exist. It is conjectured that these shocks comprise a distinct class. Decelerated solutions of the RH conditions are shown to exist only under specific conditions for shocks with reflected particles. Velocity flows both parallel and oblique to the perpendicular shock (with respect to an upstream magnetic field) are considered and found to be strongly sheared.
Stationary State After a Quench to the Lieb-Liniger from Rotating BECs
NASA Astrophysics Data System (ADS)
Bucciantini, Leda
2016-08-01
We study long-time dynamics of a bosonic system after suddenly switching on repulsive delta-like interactions. As initial states, we consider two experimentally relevant configurations: a rotating BEC and two counter-propagating BECs with opposite momentum, both on a ring. In the first case, the rapidity distribution function for the stationary state is derived analytically and it is given by the distribution obtained for the same quench starting from a BEC, shifted by the momentum of each boson. In the second case, the rapidity distribution function is obtained numerically for generic values of repulsive interaction and initial momentum. The significant differences for the case of large versus small quenches are discussed.
Stationary spectroscopy of biotissues in vivo: Fluorescent studies of some pathological states
NASA Astrophysics Data System (ADS)
Giraev, K. M.; Ashurbekov, N. A.; Medzhidov, R. T.
2003-11-01
The stationary spectra of autofluorescence, along with the reflection coefficient at the wavelength of excitation, are measured in vivo for some stomach tissues in the case of different pathological states (dysplasia, superficial gastritis, and cancer) using a nitrogen laser as the source of excitation (λrad=337.1 nm). The fluorescence spectra obtained are decomposed into Gaussian-Lorentzian components. It is found that, in development of dysplasia and tumor processes, at least seven groups of fluorophores can be distinguished that form the entire emission spectrum. The ratio between the fluorescence intensities of flavins and NAD(P)H is determined and the degree of respiratory activity of cells estimated for the states considered. The quantum yields of fluorescence of the biotissues under investigation are estimated.
Stationary distribution of self-organized states and biological information generation
Woo, Hyung Jun
2013-01-01
Self-organization, where spontaneous orderings occur under driven conditions, is one of the hallmarks of biological systems. We consider a statistical mechanical treatment of the biased distribution of such organized states, which become favored as a result of their catalytic activity under chemical driving forces. A generalization of the equilibrium canonical distribution describes the stationary state, which can be used to model shifts in conformational ensembles sampled by an enzyme in working conditions. The basic idea is applied to the process of biological information generation from random sequences of heteropolymers, where unfavorable Shannon entropy is overcome by the catalytic activities of selected genes. The ordering process is demonstrated with the genetic distance to a genotype with high catalytic activity as an order parameter. The resulting free energy can have multiple minima, corresponding to disordered and organized phases with first-order transitions between them. PMID:24281357
Core-halo quasi-stationary states in the Hamiltonian mean-field model
NASA Astrophysics Data System (ADS)
Konishi, Eiji
2016-04-01
A characteristic feature of long-range interacting systems is that they become trapped in a non-equilibrium and long-lived quasi-stationary state (QSS) during the early stages of their development. We present a comprehensive review of recent studies of the core-halo structure of QSSs, in the Hamiltonian mean-field model (HMF), which is a mean-field model of mutually coupled ferromagnetic XY spins located at a point, obtained by starting from various unsteady rectangular water-bag type initial phase-space distributions. The main result exposed in this review is that the core-halo structure can be described by the superposition of two independent Lynden-Bell distributions. We discuss the completeness of collisionless relaxation of this double Lynden-Bell distribution by using both of Lynden-Bell entropy and double Lynden-Bell entropy for the systems at low energies per particle.
NASA Technical Reports Server (NTRS)
Morozov, S. K.; Krasitskiy, O. P.
1978-01-01
A computational scheme and a standard program is proposed for solving systems of nonstationary spatially one-dimensional nonlinear differential equations using Newton's method. The proposed scheme is universal in its applicability and its reduces to a minimum the work of programming. The program is written in the FORTRAN language and can be used without change on electronic computers of type YeS and BESM-6. The standard program described permits the identification of nonstationary (or stationary) solutions to systems of spatially one-dimensional nonlinear (or linear) partial differential equations. The proposed method may be used to solve a series of geophysical problems which take chemical reactions, diffusion, and heat conductivity into account, to evaluate nonstationary thermal fields in two-dimensional structures when in one of the geometrical directions it can take a small number of discrete levels, and to solve problems in nonstationary gas dynamics.
NASA Astrophysics Data System (ADS)
Sourie, Aurélien; Oertel, Micaela; Novak, Jérôme
2016-04-01
We present a numerical model for uniformly rotating superfluid neutron stars in a fully general relativistic framework with, for the first time, realistic microphysics including entrainment. We compute stationary and axisymmetric configurations of neutron stars composed of two fluids, namely superfluid neutrons and charged particles (protons and electrons), rotating with different rates around a common axis. Both fluids are coupled by entrainment, a nondissipative interaction which in the case of a nonvanishing relative velocity between the fluids causes the fluid momenta to be not aligned with the respective fluid velocities. We extend the formalism put forth by Comer and Joynt in order to calculate the equation of state (EOS) and entrainment parameters for an arbitrary relative velocity as far as superfluidity is maintained. The resulting entrainment matrix fulfills all necessary sum rules, and in the limit of small relative velocity our results agree with Fermi liquid theory ones derived to lowest order in the velocity. This formalism is applied to two new nuclear equations of state which are implemented in the numerical model, which enables us to obtain precise equilibrium configurations. The resulting density profiles and moments of inertia are discussed employing both EOSs, showing the impact of entrainment and the dependence on the EOS.
Rao, N.N.
1998-01-01
A systematic analysis of the stationary propagation of nonlinearly coupled electromagnetic and ion-acoustic waves in an unmagnetized plasma via the ponderomotive force is carried out. For small but finite amplitudes, the governing equations have a Hamiltonian structure, but with a kinetic energy term that is not positive definite. The Hamiltonian is similar to the well-known H{acute e}non{endash}Heiles Hamiltonian of nonlinear dynamics, and is completely integrable in three regimes of the allowed parameter space. The corresponding second invariants of motion are also explicitly obtained. The integrable parameter regimes correspond to supersonic values of the Mach number, which characterizes the propagation speed of the coupled waves. On the other hand, in the sub- as well as near-sonic regimes, the coupled mode equations admit different types of exact analytical solutions, which represent nonlinear localized eigenstates of the electromagnetic field trapped in the density cavity due to the ponderomotive potential. While the density cavity has always a single-dip structure, for larger amplitudes it can support higher-order modes having a larger number of nodes in the electromagnetic field. In particular, we show the existence of a new type of localized electromagnetic wave whose field intensity has a triple-hump structure. For typical parameter values, the triple-hump solitons propagate with larger Mach numbers that are closer to the sonic limit than the single- as well as the double-hump solitons, but carry a lesser amount of the electromagnetic field energy. A comparison between the different types of solutions is carried out. The possibility of the existence of trapped electromagnetic modes having a larger number of humps is also discussed. {copyright} {ital 1998 American Institute of Physics.}
Stationary states of fermions in a sign potential with a mixed vector–scalar coupling
Castilho, W.M. Castro, A.S. de
2014-01-15
The scattering of a fermion in the background of a sign potential is considered with a general mixing of vector and scalar Lorentz structures with the scalar coupling stronger than or equal to the vector coupling under the Sturm–Liouville perspective. When the vector coupling and the scalar coupling have different magnitudes, an isolated solution shows that the fermion under a strong potential can be trapped in a highly localized region without manifestation of Klein’s paradox. It is also shown that the lonely bound-state solution disappears asymptotically as one approaches the conditions for the realization of spin and pseudospin symmetries. -- Highlights: •Scattering of fermions in a sign potential assessed under a Sturm–Liouville perspective. •An isolated bounded solution. •No pair production despite the high localization. •No bounded solution under exact spin and pseudospin symmetries.
Lantz, Andrew W; Pino, Verónica; Anderson, Jared L; Armstrong, Daniel W
2006-05-19
The use of micelles in ionic liquid based gas-chromatography stationary phases was evaluated using equations derived for a "three-phase" model. This model allows the determination of all three partition coefficients involved in the system, and elucidates the micellar contribution to retention and selectivity. Four types of micellar-ionic liquid columns were examined in this study: 1-butyl-3-methylimidazolium chloride with sodium dodecylsulfate or dioctyl sulfosuccinate, and 1-butyl-3-methylimidazolium hexafluorophosphate with polyoxyethylene-100-stearyl ether or polyoxyethylene-23-lauryl ether. The partition coefficients were measured for a wide range of probe molecules capable of a variety of types and magnitudes of interactions. In general, most probe molecules preferentially partitioned to the micellar pseudophase over the bulk ionic liquid component of the stationary phase. Therefore, addition of surfactant to the stationary phase usually resulted in greater solute retention. It is also shown that the selectivity of the stationary phase is significantly altered by the presence of micelles, either by enhancing or lessening the separation. The effects of surfactant on the interaction parameters of the stationary phase are determined using the Abraham solvation parameter model. The addition of sodium dodecylsulfate and dioctyl sulfosuccinate to 1-butyl-3-methylimidazolium chloride stationary phases generally increased the phase's hydrogen bond basicity and increased the level of dispersion interaction. Polyoxyethylene-100-stearyl ether and polyoxyethylene-23-lauryl ether surfactants, however, enhanced the pi-pi/n-pi, polarizability/dipolarity, and hydrogen bond basicity interactions of 1-butyl-3-methylimidazolium hexafluorophosphate to a greater degree than the ionic surfactants with 1-butyl-3-methylimidazolium chloride. However, these nonionic surfactants appeared to hinder the ability of the stationary phase to interact with solutes via dispersion forces
Infinitely many solutions for the stationary Kirchhoff problems involving the fractional p-Laplacian
NASA Astrophysics Data System (ADS)
Mingqi, Xiang; Molica Bisci, Giovanni; Tian, Guohua; Zhang, Binlin
2016-02-01
The aim of this paper is to establish the multiplicity of weak solutions for a Kirchhoff-type problem driven by a fractional p-Laplacian operator with homogeneous Dirichlet boundary conditions: where Ω is an open bounded subset of {{{R}}N} with Lipshcitz boundary \\partial Ω , (-Δ )ps is the fractional p-Laplacian operator with 0 < s < 1 < p < N such that sp < N, M is a continuous function and f is a Carathéodory function satisfying the Ambrosetti-Rabinowitz-type condition. When f satisfies the suplinear growth condition, we obtain the existence of a sequence of nontrivial solutions by using the symmetric mountain pass theorem; when f satisfies the sublinear growth condition, we obtain infinitely many pairs of nontrivial solutions by applying the Krasnoselskii genus theory. Our results cover the degenerate case in the fractional setting: the Kirchhoff function M can be zero at zero.
Stationary states of a pair of tangent identical vortex spots in a barotropic ocean
NASA Astrophysics Data System (ADS)
Shavlyugin, A. I.
2016-01-01
The method for constructing limiting forms of steady states of vortex patches characterized by the presence of corners on the boundary is presented. The method is based on a continuation of the solution (the streamline which must coincide with the vortex boundary) when passing through the singular point to those part of the common vortex border whose tangent is continuous at the critical point. Limiting steady states of a pair of identical touching vortex patches are constructed for the cases of unlimited and circular barotropic oceans. It is found that, for the case of a circular ocean, the solution of maximum area is the domain bounded by two diameters intersecting at right angles. This conclusion is also valid for an unlimited ocean when the vortex pair of infinite area takes even/odd quadrants whose boundaries are formed by the asymptotes of solutions of finite area. The results add new members to the set of known exact analytical solutions of the problem of steady states of vortex patches.
Yamaki, Masahiro; Teranishi, Yoshiaki; Nakamura, Hiroki; Lin, Sheng Hsien; Fujimura, Yuichi
2016-01-21
The electron angular momentum is a fundamental quantity of high-symmetry aromatic ring molecules and finds many applications in chemistry such as molecular spectroscopy. The stationary angular momentum or unidirectional rotation of π electrons is generated by the excitation of a degenerated electronic excited state by a circularly-polarized photon. For low-symmetry aromatic ring molecules having non-degenerate states, such as chiral aromatic ring molecules, on the other hand, whether stationary angular momentum can be generated or not is uncertain and has not been clarified so far. We have found by both theoretical treatments and quantum optimal control (QOC) simulations that a stationary angular momentum can be generated even from a low-symmetry aromatic ring molecule. The generation mechanism can be explained in terms of the creation of a dressed-state, and the maximum angular momentum is generated by the dressed state with an equal contribution from the relevant two excited states in a simple three-electronic state model. The dressed state is formed by inducing selective nonresonant transitions between the ground and each excited state by two lasers with the same frequency but having different polarization directions. The selective excitation can be carried out by arranging each photon-polarization vector orthogonal to the electronic transition moment of the other transition. We have successfully analyzed the results of the QOC simulations of (P)-2,2'-biphenol of axial chirality in terms of the analytically determined optimal laser fields. The present findings may open up new types of chemical dynamics and spectroscopy by utilizing strong stationary ring currents and current-induced magnetic fields, which are created at a local site of large compounds such as biomolecules. PMID:26670839
Yu, Huapeng; Zhu, Hai; Gao, Dayuan; Yu, Meng; Wu, Wenqi
2015-01-01
The Kalman filter (KF) has always been used to improve north-finding performance under practical conditions. By analyzing the characteristics of the azimuth rotational inertial measurement unit (ARIMU) on a stationary base, a linear state equality constraint for the conventional KF used in the fine north-finding filtering phase is derived. Then, a constrained KF using the state equality constraint is proposed and studied in depth. Estimation behaviors of the concerned navigation errors when implementing the conventional KF scheme and the constrained KF scheme during stationary north-finding are investigated analytically by the stochastic observability approach, which can provide explicit formulations of the navigation errors with influencing variables. Finally, multiple practical experimental tests at a fixed position are done on a postulate system to compare the stationary north-finding performance of the two filtering schemes. In conclusion, this study has successfully extended the utilization of the stochastic observability approach for analytic descriptions of estimation behaviors of the concerned navigation errors, and the constrained KF scheme has demonstrated its superiority over the conventional KF scheme for ARIMU stationary north-finding both theoretically and practically. PMID:25688588
Yu, Huapeng; Zhu, Hai; Gao, Dayuan; Yu, Meng; Wu, Wenqi
2015-01-01
The Kalman filter (KF) has always been used to improve north-finding performance under practical conditions. By analyzing the characteristics of the azimuth rotational inertial measurement unit (ARIMU) on a stationary base, a linear state equality constraint for the conventional KF used in the fine north-finding filtering phase is derived. Then, a constrained KF using the state equality constraint is proposed and studied in depth. Estimation behaviors of the concerned navigation errors when implementing the conventional KF scheme and the constrained KF scheme during stationary north-finding are investigated analytically by the stochastic observability approach, which can provide explicit formulations of the navigation errors with influencing variables. Finally, multiple practical experimental tests at a fixed position are done on a postulate system to compare the stationary north-finding performance of the two filtering schemes. In conclusion, this study has successfully extended the utilization of the stochastic observability approach for analytic descriptions of estimation behaviors of the concerned navigation errors, and the constrained KF scheme has demonstrated its superiority over the conventional KF scheme for ARIMU stationary north-finding both theoretically and practically. PMID:25688588
Separation of stationary and non-stationary sources with a generalized eigenvalue problem.
Hara, Satoshi; Kawahara, Yoshinobu; Washio, Takashi; von Bünau, Paul; Tokunaga, Terumasa; Yumoto, Kiyohumi
2012-09-01
Non-stationary effects are ubiquitous in real world data. In many settings, the observed signals are a mixture of underlying stationary and non-stationary sources that cannot be measured directly. For example, in EEG analysis, electrodes on the scalp record the activity from several sources located inside the brain, which one could only measure invasively. Discerning stationary and non-stationary contributions is an important step towards uncovering the mechanisms of the data generating system. To that end, in Stationary Subspace Analysis (SSA), the observed signal is modeled as a linear superposition of stationary and non-stationary sources, where the aim is to separate the two groups in the mixture. In this paper, we propose the first SSA algorithm that has a closed form solution. The novel method, Analytic SSA (ASSA), is more than 100 times faster than the state-of-the-art, numerically stable, and guaranteed to be optimal when the covariance between stationary and non-stationary sources is time-constant. In numerical simulations on wide range of settings, we show that our method yields superior results, even for signals with time-varying group-wise covariance. In an application to geophysical data analysis, ASSA extracts meaningful components that shed new light on the Pi 2 pulsations of the geomagnetic field. PMID:22551683
Cerri, S. S.; Pegoraro, F.; Califano, F.; Jenko, F.
2014-11-15
Observations and numerical simulations of laboratory and space plasmas in almost collisionless regimes reveal anisotropic and non-gyrotropic particle distribution functions. We investigate how such states can persist in the presence of a sheared flow. We focus our attention on the pressure tensor equation in a magnetized plasma and derive analytical self-consistent plasma equilibria which exhibit a novel asymmetry with respect to the magnetic field direction. These results are relevant for investigating, within fluid models that retain the full pressure tensor dynamics, plasma configurations where a background shear flow is present.
NASA Technical Reports Server (NTRS)
Gabrielsen, R. E.; Karel, S.
1975-01-01
An algorithm for solving the nonlinear stationary Navier-Stokes problem is developed. Explicit error estimates are given. This mathematical technique is potentially adaptable to the separation problem.
Perrier, Frédéric; Le Mouël, Jean-Louis
2016-04-15
The transition zone between free and underground atmospheres hosts spectacular phenomena, as demonstrated by temperature measurements performed in the 4.6m diameter and 20m deep vertical access pit of an abandoned underground quarry located in Vincennes, near Paris. In summer, a stable stratification of the atmosphere is maintained, with coherent temperature variations associated with atmospheric pressure changes, with a barometric tide S2 larger than 0.1°C peak to peak. When the winter regime of turbulent cold air avalanches is initiated, stratification with pressure induced signals can be restored transiently in the upper part of the pit, while the lower part remains fully mixed and insensitive to pressure variations. The amplitude of the pressure to temperature transfer function increases with frequency below 5×10(-4)Hz, with values at 3×10(-5)Hz varying from 0.1°C·hPa(-1) at the bottom up to 2°C·hPa(-1) towards the top of the pit. These temperature variations are accounted for by cave breathing, which is pressure induced motion of air amplified by the large volume of the quarry. This understanding is supported by a numerical model including advective heat transport, heat diffusion, and heat exchange with the pit walls. Mean lifetime in the pit is of the order of 9 to 13h, and barometric pumping results in an effective ventilation rate of the quarry of the order of 10(-7)s(-1). This study illustrates the important role of barometric pumping in heat and matter transport between atmosphere and lithosphere. The resulting stationary and transient states, revealed in this pit, are probably a general feature of functioning interface systems, and therefore are an important aspect to consider in problems of contaminant transport, or the preservation of precious heritage such as rare ecosystems or painted caves. PMID:26855357
Ibrahim, R. S.; El-Kalaawy, O. H.
2006-10-15
The relativistic nonlinear self-consistent equations for a collisionless cold plasma with stationary ions [R. S. Ibrahim, IMA J. Appl. Math. 68, 523 (2003)] are extended to 3 and 3+1 dimensions. The resulting system of equations is reduced to the sine-Poisson equation. The truncated Painleve expansion and reduction of the partial differential equation to a quadrature problem (RQ method) are described and applied to obtain the traveling wave solutions of the sine-Poisson equation for stationary and nonstationary equations in 3 and 3+1 dimensions describing the charge-density equilibrium configuration model.
NASA Technical Reports Server (NTRS)
Skarda, J. Raymond Lee; McCaughan, Frances E.
1998-01-01
Stationary onset of convection due to surface tension variation in an unbounded multicomponent fluid layer is considered. Surface deformation is included and general flux boundary conditions are imposed on the stratifying agencies (temperature/composition) disturbance equations. Exact solutions are obtained to the general N-component problem for both finite and infinitesimal wavenumbers. Long wavelength instability may coexist with a finite wavelength instability for certain sets of parameter values, often referred to as frontier points. For an impermeable/insulated upper boundary and a permeable/conductive lower boundary, frontier boundaries are computed in the space of Bond number, Bo, versus Crispation number, Cr, over the range 5 x 10(exp -7) less than or equal to Bo less than or equal to 1. The loci of frontier points in (Bo, Cr) space for different values of N, diffusivity ratios, and, Marangoni numbers, collapsed to a single curve in (Bo, D(dimensional variable)Cr) space, where D(dimensional variable) is a Marangoni number weighted diffusivity ratio.
NASA Astrophysics Data System (ADS)
Jasinski, Jerzy
2015-05-01
In the paper propagation of axially-symmetric (1+2)D beam in nonlinear medium with dual-power nonlinearity is analyzed. The ordinary differential equation for transverse stationary profile of the propagating field is derived and solved using a perturbation technique. The simple analytical formulas for the three lowest order solutions are obtained. They describe fields of algebraic profiles. The zero order solution satisfies exactly the nonlinear Schrödinger equation in (1+2)D case. Higher order solutions are determined by propagation constant and describe fields of different initial amplitude. The accuracy of approximation and stability of the obtained solutions are discussed.
Stationary nonlinear Airy beams
Lotti, A.; Faccio, D.; Couairon, A.; Papazoglou, D. G.; Panagiotopoulos, P.; Tzortzakis, S.; Abdollahpour, D.
2011-08-15
We demonstrate the existence of an additional class of stationary accelerating Airy wave forms that exist in the presence of third-order (Kerr) nonlinearity and nonlinear losses. Numerical simulations and experiments, in agreement with the analytical model, highlight how these stationary solutions sustain the nonlinear evolution of Airy beams. The generic nature of the Airy solution allows extension of these results to other settings, and a variety of applications are suggested.
NASA Astrophysics Data System (ADS)
Livadiotis, G.; McComas, D. J.
2009-12-01
In situ observations of solar wind at 1 AU have occasionally detected ion distributions in equilibrium, where the three-dimensional spectral slope or k-index approaches infinity (a Maxwellian distribution) [e.g., Hammond, C. M., et al. (1996), J. Geophys. Res., 100, 7881-7889]. More commonly, however, suprathermal particle distributions in the solar wind routinely show highly non-equilibrium stationary states, with a k~1.5 [Fisk, L. A., and G. Gloeckler (2006), Astrophys. J., 640, L79-L82], while other observations from Voyager 1 detected k~1.63 in the inner heliosheath, beyond the termination shock [Decker, R. B., et al. (2005), Science, 309, 2020-2024]. While this value is close to 1.5, the observations demonstrated a clear statistical difference between these two indices. Finally, recent observations show distributions for which k~2.45 is a special value, separating indices that appear to be near or far from equilibrium [e.g., Dayeh, M. A., et al. (2009), Astrophys. J., 693, 1588-1600; Dialynas, K., et al. (2009), J. Geophys. Res., 114, A01212]. In this study we show how all of these special values of k~1.5, 1.63, 2.45, and infinity can be predicted by a special relationship of the entropy, defined in the framework of non-extensive Statistical Mechanics as applied to space physics [Livadiotis, G., and D. McComas (2009), in Press in JGR-Space Physics], which characterizes plasmas in stationary states out of equilibrium. Amazingly, the four values observed in the solar wind plasma and mentioned above are uniquely identified with the four special points in the derived entropy function. This correlation suggests that the observations are detecting the primacy of these stationary states.
Influence of Copper Vapor on Low-Voltage Circuit Breaker Arcs During Stationary and Moving States
NASA Astrophysics Data System (ADS)
Ma, Qiang; Rong, Mingzhe; Wu, Yi; Xu, Tiejun; Sun, Zhiqiang
2008-06-01
The influence of copper vapor on the low-voltage circuit breaker arcs is studied. A three-dimensional (3-D) magnetohydrodynamics(MHD) model of arc motion under the effect of external magnetic field is built up. By adopting the commercial computational fluid dynamics (CFD) package FLUENT based on control-volume method, the above MHD model is solved. For the mediums of air-1% Cu and air-10% Cu, the distributions of stationary temperature, pressure, electrical potential and the arc motion processes are compared with those of a pure air arc. The copper vapor diffusion process in the arc chamber and the distribution of copper vapor mass concentration are also simulated. The results shows that the copper vapor has a cooling effect on the arc plasma and can decrease the stationary voltage as well. Moreover, the presence of copper vapor can decelerate the arc motion in the quenching chambers. The maximal copper vapor concentration locates behind the arc root because of the existence of a “double vortex" near the electrodes.
NASA Astrophysics Data System (ADS)
Chen, Sheng; Täuber, Uwe C.
2015-03-01
Spatially extended stochastic models for predator-prey competition and coexistence display complex, correlated spatio-temporal structures and are governed by remarkably large fluctuations. Both populations are characterized by damped erratic oscillations whose properties are governed by the reaction rates. Here, we specifically study a stochastic lattice Lotka-Volterra model by means of Monte Carlo simulations that impose spatial restrictions on the number of occupants per site. The system tends to relax into a quasi-stationary state, independent of the imposed initial conditions. We investigate the non-equilibrium relaxation between two such quasi-stationary states, following an instantaneous change of the predation rate. The ensuing relaxation times are measured via the peak width of the population density Fourier transforms. As expected, we find that the initial state only influences the oscillations for the duration of this relaxation time, implying that the system quickly loses any memory of the initial configuration. Research supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-FG02-09ER46613.
Hydrogen Storage Materials for Mobile and Stationary Applications: Current State of the Art.
Lai, Qiwen; Paskevicius, Mark; Sheppard, Drew A; Buckley, Craig E; Thornton, Aaron W; Hill, Matthew R; Gu, Qinfen; Mao, Jianfeng; Huang, Zhenguo; Liu, Hua Kun; Guo, Zaiping; Banerjee, Amitava; Chakraborty, Sudip; Ahuja, Rajeev; Aguey-Zinsou, Kondo-Francois
2015-09-01
One of the limitations to the widespread use of hydrogen as an energy carrier is its storage in a safe and compact form. Herein, recent developments in effective high-capacity hydrogen storage materials are reviewed, with a special emphasis on light compounds, including those based on organic porous structures, boron, nitrogen, and aluminum. These elements and their related compounds hold the promise of high, reversible, and practical hydrogen storage capacity for mobile applications, including vehicles and portable power equipment, but also for the large scale and distributed storage of energy for stationary applications. Current understanding of the fundamental principles that govern the interaction of hydrogen with these light compounds is summarized, as well as basic strategies to meet practical targets of hydrogen uptake and release. The limitation of these strategies and current understanding is also discussed and new directions proposed. PMID:26033917
Mallory, Kristina; Van Gorder, Robert A
2015-07-01
Stationary solutions for the cubic nonlinear Schrödinger equation modeling Bose-Einstein condensates (BECs) confined in three spatial dimensions by general forms of a potential are studied through a perturbation method and also numerically. Note that we study both repulsive and attractive BECs under similar frameworks in order to deduce the effects of the potentials in each case. After outlining the general framework, solutions for a collection of specific confining potentials of physical relevance to experiments on BECs are provided in order to demonstrate the approach. We make several observations regarding the influence of the particular potentials on the behavior of the BECs in these cases, comparing and contrasting the qualitative behavior of the attractive and repulsive BECs for potentials of various strengths and forms. Finally, we consider the nonperturbative where the potential or the amplitude of the solutions is large, obtaining various qualitative results. When the kinetic energy term is small (relative to the nonlinearity and the confining potential), we recover the expected Thomas-Fermi approximation for the stationary solutions. Naturally, this also occurs in the large mass limit. Through all of these results, we are able to understand the qualitative behavior of spherical three-dimensional BECs in weak, intermediate, or strong confining potentials. PMID:26274295
The phase delay and its complex time: From stationary states up to wave packets
Grossel, Ph.
2013-03-15
Complex time is often invoked about tunneling effect where the classical phase delay is completed with a crucial filter effect. Usually the complex times are obtained by considering the flux-flux correlation function, but this can be obtained by a very simple approach using the search of the maximum of the generalized complex phase function, including the amplitude of the wave function. Various aspects of the phase delay are presented in the case of wave packets impinging on simple or resonant quantum barriers. Formal links with the classical mechanics give birth to quasi-trajectories of the quantum particle, totally compatible with the quantum mechanics. - Highlights: Black-Right-Pointing-Pointer The stationary phase method is extended in including the variations of the spectra. Black-Right-Pointing-Pointer The complex phase delay leads to a complex trajectory inside and out-side the barrier. Black-Right-Pointing-Pointer Examples of quasi-trajectories are given in case of different quantum barriers. Black-Right-Pointing-Pointer Phase delays are specified for resonant tunneling or above-barrier wave-packets. Black-Right-Pointing-Pointer The coherence between the quasi-trajectories and quantum mechanics is shown.
Lecarpentier, Yves; Claes, Victor; Hébert, Jean-Louis; Krokidis, Xénophon; Blanc, François-Xavier; Michel, Francine; Timbely, Oumar
2015-01-01
All near-equilibrium systems under linear regime evolve to stationary states in which there is constant entropy production rate. In an open chemical system that exchanges matter and energy with the exterior, we can identify both the energy and entropy flows associated with the exchange of matter and energy. This can be achieved by applying statistical mechanics (SM), which links the microscopic properties of a system to its bulk properties. In the case of contractile tissues such as human placenta, Huxley's equations offer a phenomenological formalism for applying SM. SM was investigated in human placental stem villi (PSV) (n = 40). PSV were stimulated by means of KCl exposure (n = 20) and tetanic electrical stimulation (n = 20). This made it possible to determine statistical entropy (S), internal energy (E), affinity (A), thermodynamic force (A / T) (T: temperature), thermodynamic flow (v) and entropy production rate (A / T x v). We found that PSV operated near equilibrium, i.e., A ≺≺ 2500 J/mol and in a stationary linear regime, i.e., (A / T) varied linearly with v. As v was dramatically low, entropy production rate which quantified irreversibility of chemical processes appeared to be the lowest ever observed in any contractile system. PMID:26569482
Lecarpentier, Yves; Claes, Victor; Hébert, Jean-Louis; Krokidis, Xénophon; Blanc, François-Xavier; Michel, Francine; Timbely, Oumar
2015-01-01
All near-equilibrium systems under linear regime evolve to stationary states in which there is constant entropy production rate. In an open chemical system that exchanges matter and energy with the exterior, we can identify both the energy and entropy flows associated with the exchange of matter and energy. This can be achieved by applying statistical mechanics (SM), which links the microscopic properties of a system to its bulk properties. In the case of contractile tissues such as human placenta, Huxley’s equations offer a phenomenological formalism for applying SM. SM was investigated in human placental stem villi (PSV) (n = 40). PSV were stimulated by means of KCl exposure (n = 20) and tetanic electrical stimulation (n = 20). This made it possible to determine statistical entropy (S), internal energy (E), affinity (A), thermodynamic force (A / T) (T: temperature), thermodynamic flow (v) and entropy production rate (A / T x v). We found that PSV operated near equilibrium, i.e., A ≺≺ 2500 J/mol and in a stationary linear regime, i.e., (A / T) varied linearly with v. As v was dramatically low, entropy production rate which quantified irreversibility of chemical processes appeared to be the lowest ever observed in any contractile system. PMID:26569482
NASA Astrophysics Data System (ADS)
Mallory, Kristina; Van Gorder, Robert A.
2013-07-01
Stationary solutions for the 1+1 cubic nonlinear Schrödinger equation modeling repulsive Bose-Einstein condensates (BEC) in a small potential are obtained through a form of nonlinear perturbation. In particular, for sufficiently small potentials, we determine the perturbation theory of stationary solutions, by use of an expansion in Jacobi elliptic functions. This idea was explored before in order to obtain exact solutions [Bronski, Carr, Deconinck, and Kutz, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.86.1402 86, 1402 (2001)], where the potential itself was fixed to be a Jacobi elliptic function, thereby reducing the nonlinear ODE into an algebraic equation, (which could be easily solved). However, in the present paper, we outline the perturbation method for completely general potentials, assuming only that such potentials are locally small. We do not need to assume that the nonlinearity is small, as we perform a sort of nonlinear perturbation by allowing the zeroth-order perturbation term to be governed by a nonlinear equation. This allows us to consider even poorly behaved potentials, so long as they are bounded locally. We demonstrate the effectiveness of this approach by considering a number of specific potentials: for the simplest potentials, and we recover results from the literature, while for more complicated potentials, our results are new. Dark soliton solutions are constructed explicitly for some cases, and we obtain the known one-soliton tanh-type solution in the simplest setting for the repulsive BEC. Note that we limit our results to the repulsive case; similar results can be obtained for the attractive BEC case.
Theory of stationary ultarshort pulses in solid-state laserswith passive mode locking
Komarov, K.P.
1986-02-01
The formation of steady-state pulses in solid-state lasers with passive mode locking is investigated under conditions when the refractive index is frequency dispersive and nonlinear. The case of a noninertial absorber is considered as well as that of an inertial one. It is shown that when the nonlinearity of the refractive index exceeds a certain critical level phase modulation of the pulse leads to instability of the steady-state regime. The possibility is discussed of forming extremely short pulses in wide-band amplifying media such as alexandrite.
NASA Astrophysics Data System (ADS)
Pluchino, Alessandro; Rapisarda, Andrea; Tsallis, Constantino
2008-05-01
We give a closer look at the Central Limit Theorem (CLT) behavior in quasi-stationary states of the Hamiltonian Mean Field model, a paradigmatic one for long-range-interacting classical many-body systems. We present new calculations which show that, following their time evolution, we can observe and classify three kinds of long-standing quasi-stationary states (QSS) with different correlations. The frequency of occurrence of each class depends on the size of the system. The different microscopic nature of the QSS leads to different dynamical correlations and therefore to different results for the observed CLT behavior.
The features of a non-stationary state of stress in the elastic multisupport construction
NASA Astrophysics Data System (ADS)
Ashirbayev, Nurgali; Ashirbayeva, Zhansaya; Abzhapbarov, Azimkhan; Shomanbayeva, Manat
2016-08-01
The paper deals with the problem of propagation of unsteady elastic waves in an elastic multisupport construction, which is a rectangular strip. The mixed problem is formulated in terms of the stress and velocity and is numerically modeled using an explicit difference scheme through computation based on the method of spatial characteristics. The main objective of this study is to analyze the impact of the gap in the boundary conditions on the propagation of wave processes in the internal points of the studied elastic medium. The concentration of dynamic stresses was investigated in the vicinity of the gap of the boundary conditions. The results of the study were brought to the numerical solution.
Noguera, Norman; Rózga, Krzysztof
2015-07-15
In this work, one provides a justification of the condition that is usually imposed on the parameters of the hypergeometric equation, related to the solutions of the stationary Schrödinger equation for the harmonic oscillator in two-dimensional constant curvature spaces, in order to determine the solutions which are square-integrable. One proves that in case of negative curvature, it is a necessary condition of square integrability and in case of positive curvature, a necessary condition of regularity. The proof is based on the analytic continuation formulas for the hypergeometric function. It is observed also that the same is true in case of a slightly more general potential than the one for harmonic oscillator.
STATE-OF-THE-ART COMBUSTION MODIFICATION NOX CONTROL FOR STATIONARY COMBUSTION EQUIPMENT
The paper is a brief discussion and summary of state-of-the-art combustion modification NOx control technology for boilers and industrial process combustion equipment. These combustion modification techniques, when properly applied, offer the potential for cost-effective NOx cont...
Effect of interference between two colored noises on the stationary states of a Brownian particle.
Mondal, Shrabani; Bag, Bidhan Chandra
2015-04-01
In this paper we present properties of an external colored cross-correlated noise-driven Brownian system which is coupled to a thermal bath. Multiplicative cross-correlated noises can stabilize the transition state. Thus by monitoring the interference between the noises one can understand the mechanism of a chemical reaction. At the same time, we have investigated how the interference affects the barrier-crossing dynamics. In its presence breakdown of the Arrhenius result occurs. The breakdown becomes prominent if the multiplicative noises become additive in nature. We have also investigated how the power law behavior of the rate constant as a function of damping strength is affected by the properties of external colored noises. Furthermore, we have observed that multiplicative colored cross-correlated noises can induce the resonant activation phenomenon. PMID:25974476
Effect of interference between two colored noises on the stationary states of a Brownian particle
NASA Astrophysics Data System (ADS)
Mondal, Shrabani; Bag, Bidhan Chandra
2015-04-01
In this paper we present properties of an external colored cross-correlated noise-driven Brownian system which is coupled to a thermal bath. Multiplicative cross-correlated noises can stabilize the transition state. Thus by monitoring the interference between the noises one can understand the mechanism of a chemical reaction. At the same time, we have investigated how the interference affects the barrier-crossing dynamics. In its presence breakdown of the Arrhenius result occurs. The breakdown becomes prominent if the multiplicative noises become additive in nature. We have also investigated how the power law behavior of the rate constant as a function of damping strength is affected by the properties of external colored noises. Furthermore, we have observed that multiplicative colored cross-correlated noises can induce the resonant activation phenomenon.
NASA Astrophysics Data System (ADS)
Singh, A.; Fisher, J.; Pai, H.; Villamizar Amaya, S.; Harmon, T. C.; Kaiser, W.
2007-12-01
Spatially distributed hydraulic and water quality property characterization is important to understanding a broad range of river issues including confluence and discharge mixing phenomena, groundwater-surface water exchanges, and flow and temperature distributions in the context of habitat restoration efforts. Such characterization efforts often need to be completed rapidly to avoid complications associated with transient upstream conditions ( e.g., reservoir operational changes, time-variable irrigation drainage). In this work, we test a non-stationary Gaussian Process (GP) model for increasing sampling efficiency during a robotic deployment of velocity (ADV) and electrical conductivity (EC) sensors across a river transect. GP modeling is a common statistical approach for addressing spatially distributed phenomena. We first develop velocity and salinity observations within the mixing zone of the Merced-San Joaquin River confluence robotically in the form of high resolution (114 point) raster scans. We train the GP model by dividing the river cross-section into three sub- regions corresponding to Merced river side (east), mixing zone (center), and San Joaquin River side (west). An information criterion was selected that assigned each observation location a quantitative value in terms of the uncertainty about our prediction of the EC value given the measurement made at that location. We then executed a path-planning algorithm optimizing 16 locations out of the original 114. Using the observations from these 16 locations, and the trained GP model, we predicted the values at the rest of the 98 unobserved locations. EC distributions are compared for the raster- and GP-based data and suggest that the GP modeling strategy is viable for enhancing sampling efficiency in the context of spatially distributed river characteristics.
Kazarian, Artaches A; Taylor, Mark R; Haddad, Paul R; Nesterenko, Pavel N; Paull, Brett
2013-11-25
The nature and extent of mixed-mode retention mechanisms evident for three structurally related, agglomerated, particle-based stationary phases were evaluated. These three agglomerated phases were Thermo Fisher ScientificIon PacAS11-HC - strong anion exchange, Thermo Fisher Scientific IonPac CS10--strong cation-exchange PS-DVB, and the Thermo Fisher Scientific Acclaim Trinity P1silica-based substrate, which is commercially marketed as a mixed-mode stationary phase. All studied phases can exhibit zwitterionic and hydrophobic properties, which contribute to the retention of charged organic analytes. A systematic approach was devised to investigate the relative ion-exchange capacities and hydrophobicities for each of the three phases, together with the effect of eluent pH upon selectivity, using a specifically selected range of anionic, cationic and neutral aromatic compounds. Investigation of the strong anion-exchange column and the Trinity P1 mixed-mode substrate, in relation to ion-exchange capacity and pH effects, demonstrated similar retention behaviour for both the anionic and ampholytic solutes, as expected from the structurally related phases. Further evaluation revealed that the ion-exchange selectivity of the mixed-mode phase exhibited properties similar to that of the strong anion-exchange column, with secondary cation-exchange selectivity, albeit with medium to high anion-exchange and cation-exchange capacities, allowing selective retention for each of the anionic, cationic and ampholytic solutes. Observed mixed-mode retention upon the examined phases was found to be a sum of anion- and cation-exchange interactions, secondary ion-exchange and hydrophobic interactions, with possible additional hydrogen bonding. Hydrophobic evaluation of the three phases revealed logP values of 0.38-0.48, suggesting low to medium hydrophobicity. These stationary phases were also benchmarked against traditional reversed-phase substrates namely, octadecylsilica YMC-Pac Pro C18
Sun, Xiang; Ladanyi, Branka M; Stratt, Richard M
2015-07-23
Experimental studies of solvation dynamics in liquids invariably ask how changing a solute from its electronic ground state to an electronically excited state affects a solution's dynamics. With traditional time-dependent-fluorescence experiments, that means looking for the dynamical consequences of the concomitant change in solute-solvent potential energy. But if one follows the shift in the dynamics through its effects on the macroscopic polarizability, as recent solute-pump/solvent-probe spectra do, there is another effect of the electronic excitation that should be considered: the jump in the solute's own polarizability. We examine the spectroscopic consequences of this solute polarizability change in the classic example of the solvation dye coumarin 153 dissolved in acetonitrile. After demonstrating that standard quantum chemical methods can be used to construct accurate multisite models for the polarizabilities of ground- and excited-state solvation dyes, we show via simulation that this polarizability change acts as a contrast agent, significantly enhancing the observable differences in optical-Kerr spectra between ground- and excited-state solutions. A comparison of our results with experimental solute-pump/solvent-probe spectra supports our interpretation and modeling of this spectroscopy. We predict, in particular, that solute-pump/solvent-probe spectra should be sensitive to changes in both the solvent dynamics near the solute and the electronic-state-dependence of the solute's own rotational dynamics. PMID:25299940
Concepts for future solid state lighting solutions
NASA Astrophysics Data System (ADS)
von Malm, N.; Wirth, R.; Illek, S.; Steegmüller, U.
2010-08-01
In this contribution the relevant technological aspects of LED-based lamps for solid state lighting are discussed. In addition to general energy efficiency considerations improvements in LED chip technology and white light generation are presented.
DG method for the numerical solution of the state problem in shape optimization
NASA Astrophysics Data System (ADS)
Hozman, J.; ŠimÅ¯nková, M.
2015-11-01
In this article we are concerned with the discontinuous Galerkin (DG) method in connection with the numerical solution of the state problem in the field of shape optimization techniques. The presented state problem is described by the stationary energy equation of the system of the mould, glass piece, plunger and plunger cavity arising from the forming process in the glass industry. The attention is paid to the development of the numerical scheme based on the piecewise polynomial, generally discontinuous approximation, which enables to better resolve various phenomena typical for such a heterogeneous medium problem, compared with standard common numerical techniques. The studied problem is supplemented with the preliminary numerical results demonstrating the potency of the proposed scheme.
Decay of stationary light pulses in ultracold atoms
Wu Jinhui; Artoni, M.; La Rocca, G. C.
2010-03-15
We develop a general scheme for studying the optical response of ultracold atoms driven into a regime of standing-wave electromagnetically induced transparency. We rely on full numerical solutions of the Maxwell-Liouville equations without invoking secular and adiabatic approximations and arbitrary initial state assumptions. These approximations and assumptions can conceal, e.g., significant loss and diffusion responsible for the decay of stationary light pulses in cold atomic samples. The complex decay dynamics of a stationary light pulse is here analyzed in terms of higher-order spin and optical coherences that arise from nonlinear interactions of the stationary light pulse with the two counterpropagating components of a standing-wave driving field. Specific results for stationary light pulses in cold {sup 87}Rb atoms have been discussed for temperature regimes where the residual Doppler broadening is negligible.
Sharada, Shaama Mallikarjun; Bell, Alexis T. E-mail: bell@cchem.berkeley.edu; Head-Gordon, Martin E-mail: bell@cchem.berkeley.edu
2014-04-28
The cost of calculating nuclear hessians, either analytically or by finite difference methods, during the course of quantum chemical analyses can be prohibitive for systems containing hundreds of atoms. In many applications, though, only a few eigenvalues and eigenvectors, and not the full hessian, are required. For instance, the lowest one or two eigenvalues of the full hessian are sufficient to characterize a stationary point as a minimum or a transition state (TS), respectively. We describe here a method that can eliminate the need for hessian calculations for both the characterization of stationary points as well as searches for saddle points. A finite differences implementation of the Davidson method that uses only first derivatives of the energy to calculate the lowest eigenvalues and eigenvectors of the hessian is discussed. This method can be implemented in conjunction with geometry optimization methods such as partitioned-rational function optimization (P-RFO) to characterize stationary points on the potential energy surface. With equal ease, it can be combined with interpolation methods that determine TS guess structures, such as the freezing string method, to generate approximate hessian matrices in lieu of full hessians as input to P-RFO for TS optimization. This approach is shown to achieve significant cost savings relative to exact hessian calculation when applied to both stationary point characterization as well as TS optimization. The basic reason is that the present approach scales one power of system size lower since the rate of convergence is approximately independent of the size of the system. Therefore, the finite-difference Davidson method is a viable alternative to full hessian calculation for stationary point characterization and TS search particularly when analytical hessians are not available or require substantial computational effort.
Díaz, J I; Hidalgo, A; Tello, L
2014-10-01
We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge-Kutta total variation diminishing for time integration. PMID:25294969
Díaz, J. I.; Hidalgo, A.; Tello, L.
2014-01-01
We study a climatologically important interaction of two of the main components of the geophysical system by adding an energy balance model for the averaged atmospheric temperature as dynamic boundary condition to a diagnostic ocean model having an additional spatial dimension. In this work, we give deeper insight than previous papers in the literature, mainly with respect to the 1990 pioneering model by Watts and Morantine. We are taking into consideration the latent heat for the two phase ocean as well as a possible delayed term. Non-uniqueness for the initial boundary value problem, uniqueness under a non-degeneracy condition and the existence of multiple stationary solutions are proved here. These multiplicity results suggest that an S-shaped bifurcation diagram should be expected to occur in this class of models generalizing previous energy balance models. The numerical method applied to the model is based on a finite volume scheme with nonlinear weighted essentially non-oscillatory reconstruction and Runge–Kutta total variation diminishing for time integration. PMID:25294969
2011-01-01
Background The involvement of histone acetylation in facilitating gene expression is well-established, particularly in the case of histones H3 and H4. It was previously shown in Saccharomyces cerevisiae that gene expression was significantly down-regulated and chromatin more condensed in stationary phase compared to exponential phase. We were therefore interested in establishing the acetylation state of histone H3 and H4 in stationary and in exponential phase, since the regulation of this modification could contribute to transcriptional shut-down and chromatin compaction during semi-quiescence. Results We made use of nano-spray tandem mass spectrometry to perform a precursor ion scan to detect an m/z 126 immonium ion, diagnostic of an Nε-acetylated lysine residue that allowed unambiguous identification of acetylated as opposed to tri-methylated lysine. The fragmentation spectra of peptides thus identified were searched with Mascot against the Swiss-Prot database, and the y-ion and b-ion fragmentation series subsequently analyzed for mass shifts compatible with acetylated lysine residues. We found that K9, K14 and K36 of histone H3 and K12 and K16 of histone H4 were acetylated in exponential phase (bulk histones), but could not detect these modifications in histones isolated from stationary phase cells at the sensitivity level of the mass spectrometer. The corresponding un-acetylated peptides were, however, observed. A significantly higher level of acetylation of these residues in exponential phase was confirmed by immuno-blotting. Conclusion H4K16 acetylation was previously shown to disrupt formation of condensed chromatin in vitro. We propose that de-acetylation of H4K16 allowed formation of condensed chromatin in stationary phase, and that acetylation of H3K9, H3K14, H3K36, and H4K12 reflected the active transcriptional state of the yeast genome in exponential phase. PMID:21726436
Stationary Fuel Cell Evaluation (Presentation)
Kurtz, J.; Wipke, K.; Sprik, S.; Ramsden, T.; Ainscough, C.
2012-05-01
This powerpoint presentation discusses its objectives: real world operation data from the field and state-of-the-art lab; collection; analysis for independent technology validation; collaboration with industry and end users operating stationary fuel cell systems and reporting on technology status, progress and technical challenges. The approach and accomplishments are: A quarterly data analysis and publication of first technical stationary fuel cell composite data products (data through June 2012).
NASA Technical Reports Server (NTRS)
Lobashov, A. A.; Mostepanenko, V. M.
1993-01-01
The theory of quantum effects in nonlinear dielectric media is developed. The nonlinear dielectric media is influenced by an external pumping field. The diagonalization of the Hamiltonian of a quantized field is obtained by the canonical Bogoliubov transformations. The transformations allow us to obtain the general expressions for the number of created photons and for the degree of squeezing. In the case of a plane pumping wave, for example, the results are calculated by using the zero order of the secular perturbation theory, with small parameters characterizing the medium nonlinearity. The Heisenberg equations of motion are obtained for non-stationary case and a commonly used Hamiltonian is derived from the first principles of quantum electrodynamics.
l-State Solutions of Multiparameter Exponential-type Potentials
NASA Astrophysics Data System (ADS)
Peña, J. J.; García-Martínez, J.; García-Ravelo, J.; Morales, J.
2014-03-01
In the present work, bound state solutions for a class of multiparameter exponential-type potential are obtained in the frame of the Greene and Aldrich approximation for the centrifugal term. The proposal is general and their usefulness is exemplified with the treatment of the Eckart, Manning-Rosen, Hulthen and Deng Fan potentials that are obtained straightforwardly without resorting to specialized methods of solution for each specific potential, as usually is done. Furthermore, the proposal admits other approximations for the centrifugal term indicating an improvement to procedures developed with the same objective. So, our proposal can be considered as an unified treatment of the l-state solutions for exponential-type potentials and can be used to find new solvable potentials.
Steady-state axisymmetric nonlinear magnetohydrodynamic solutions with various boundary conditions
NASA Astrophysics Data System (ADS)
Wang, Lile; Lou, Yu-Qing
2014-04-01
Axisymmetric magnetohydrodynamics (MHD) can be invoked for describing astrophysical magnetized flows and formulated to model stellar magnetospheres including main-sequence stars (e.g. the Sun), compact stellar objects [e.g. magnetic white dwarfs (MWDs), radio pulsars, anomalous X-ray pulsars, magnetars, isolated neutron stars, etc.] and planets as a major step forward towards a full three-dimensional model construction. Using powerful and reliable numerical solvers based on two distinct finite-difference method and finite-element method schemes of algorithm, we examine axisymmetric steady-state or stationary MHD models in Throumoulopoulos & Tasso, finding that their separable semi-analytic non-linear solutions are actually not unique given their specific selection of several free functionals and chosen boundary conditions. Similar situations of multiple non-linear solutions with the same boundary conditions actually also happen to force-free magnetic field models of Low & Lou. The multiplicity of non-linear steady MHD solutions gives rise to differences in the total energies contained in the magnetic fields and flow velocity fields as well as in the asymptotic behaviours approaching infinity, which may in turn explain why numerical solvers tend to converge to a non-linear solution with a lower energy than the corresponding separable semi-analytic one. By properly adjusting model parameters, we invoke semi-analytic and numerical solutions to describe different kinds of scenarios, including nearly parallel case and the situation in which the misalignment between the plasma flow and magnetic field is considerable. We propose that these MHD models are capable of describing the magnetospheres of MWDs as examples of applications with moderate conditions (including magnetic field) where the typical values of several important parameters are consistent with observations. Physical parameters can also be estimated based on such MHD models directly. We discuss the challenges
Stationary rotating strings as relativistic particle mechanics
Ogawa, Kouji; Ishihara, Hideki; Saito, Shinya; Kozaki, Hiroshi; Nakano, Hiroyuki
2008-07-15
Stationary rotating strings can be viewed as geodesic motions in appropriate metrics in two-dimensional space. We obtain all solutions describing stationary rotating strings in flat spacetime as an application. These rotating strings have infinite length with various wiggly shapes. Averaged value of the string energy, the angular momentum, and the linear momentum along the string are discussed.
Tau Aggregation Propensity Engrained in Its Solution State.
Eschmann, Neil A; Do, Thanh D; LaPointe, Nichole E; Shea, Joan-Emma; Feinstein, Stuart C; Bowers, Michael T; Han, Songi
2015-11-12
A peptide fragment of the human tau protein which stacks to form neat cross β-sheet fibrils, resembling that found in pathological aggregation, (273)GKVQIINKKLDL(284) (here "R2/WT"), was modified with a spin-label at the N-terminus. With the resulting peptide, R2/G273C-SL, we probed events at time scales spanning seconds to hours after aggregation is initiated using transmission electron microscopy (TEM), thioflavin T (THT) fluorescence, ion mobility mass spectrometry (IMMS), electron paramagnetic resonance (EPR), and Overhauser dynamic nuclear polarization (ODNP) to determine if deliberate changes to its conformational states and population in solution influence downstream propensity to form fibrillar aggregates. We find varying solution conditions by adding the osmolyte urea or TMAO, or simply using different buffers (acetate buffer, phosphate buffer, or water), produces significant differences in early monomer/dimer populations and conformations. Crucially, these characteristics of the peptide in solution state before aggregation is initiated dictate the fibril formation propensity after aggregation. We conclude the driving forces that accelerate aggregation, when heparin is added, do not override the subtle intra- or interprotein interactions induced by the initial solvent conditions. In other words, the balance of protein-protein vs protein-solvent interactions present in the initial solution conditions is a critical driving force for fibril formation. PMID:26484390
Solid-State and Solution Characterization of Myricetin.
Franklin, Stephen J; Myrdal, Paul B
2015-12-01
Myricetin (MYR) is a natural compound that has been investigated as a chemopreventative agent. MYR has been shown to suppresses ultraviolet B (UVB)-induced cyclooxygenase-2 (COX-2) protein expression and reduce the incidence of UVB-induced skin tumors in mice. Despite MYR's promise as a therapeutic agent, minimal information is available to guide the progression of formulations designed for future drug development. Here, data is presented describing the solid-state and solution characterization of MYR. Investigation into the solid-state properties of MYR identified four different crystal forms, two hydrates (MYR I and MYR II) and two metastable forms (MYR IA and MYR IIA). From solubility studies, it was evident that all forms are very insoluble (<5 μg/ml) in pure water. MYR I was found to be the most stable form at 23, 35, and 56°C. Stability determination indicated that MYR undergoes rapid apparent first-order degradation under basic pH conditions, and that degradation was influenced by buffer species. Apparent first-order degradation was also seen when MYR was introduced to an oxidizing solution. Improved stability was achieved after introducing 0.1% antioxidants to the solution. MYR was found to have good stability following exposure to ultraviolet radiation (UVR), which is a consideration for topical applications. Finally, a partitioning study indicated that MYR possess a log P of 2.94 which, along with its solid-state properties, contributes to its poor aqueous solubility. Both the solid-state properties and solution stability of MYR are important to consider when developing future formulations. PMID:25986594
WEST,WP; BURRELL,KH; deGRASSIE,JS; DOYLE,EJ; GREENFIELD,CM; LASNIER,CJ; SNYDER,PB; ZENG,L
2003-08-01
OAK-B135 The quiescent H-mode (QH-mode) is an ELM-free and stationary state mode of operation discovered on DIII-D. This mode achieves H-mode levels of confinement and pedestal pressure while maintaining constant density and radiated power. The elimination of edge localized modes (ELMs) and their large divertor loads while maintaining good confinement and good density control is of interest to next generation tokamaks. This paper reports on the correlations found between selected parameters in a QH-mode database developed from several hundred DIII-D counter injected discharges. Time traces of key plasma parameters from a QH-mode discharge are shown. On DIII-D the negative going plasma current (a) indicates that the beam injection direction is counter to the plasma current direction, a common feature of all QH-modes. The D{sub {alpha}} time behavior (c) shows that soon after high powered beam heating (b) is applied, the discharge makes a transition to ELMing H-mode, then the ELMs disappear, indicating the start of the QH period that lasts for the remainder of the high power beam heating (3.5 s). Previously published work showing density and temperature profiles indicates that long-pulse, high-triangularity QH discharges develop an internal transport barrier in combination with the QH edge barrier. These discharges are known as quiescent, double-barrier discharges (QDB). The H-factor (d) and stored energy (c) rise then saturate at a constant level and the measured axial and minimum safety factors remain above 1.0 for the entire QH duration. During QDB operation the performance of the plasma can be very good, with {beta}{sub N}*H{sub 89L} product reaching 7 for > 10 energy confinement times. These discharges show promise that a stationary state can be achieved.
Bijnen, R. M. W. van; Parker, N. G.; Kokkelmans, S. J. J. M. F.; Martin, A. M.; O'Dell, D. H. J.
2010-09-15
We present a general method for obtaining the exact static solutions and collective excitation frequencies of a trapped Bose-Einstein condensate (BEC) with dipolar atomic interactions in the Thomas-Fermi regime. The method incorporates analytic expressions for the dipolar potential of an arbitrary polynomial density profile, thereby reducing the problem of handling nonlocal dipolar interactions to the solution of algebraic equations. We comprehensively map out the static solutions and excitation modes, including non-cylindrically-symmetric traps, and also the case of negative scattering length where dipolar interactions stabilize an otherwise unstable condensate. The dynamical stability of the excitation modes gives insight into the onset of collapse of a dipolar BEC. We find that global collapse is consistently mediated by an anisotropic quadrupolar collective mode, although there are two trapping regimes in which the BEC is stable against quadrupole fluctuations even as the ratio of the dipolar to s-wave interactions becomes infinite. Motivated by the possibility of a fragmented condensate in a dipolar Bose gas due to the partially attractive interactions, we pay special attention to the scissors modes, which can provide a signature of superfluidity, and identify a long-range restoring force which is peculiar to dipolar systems. As part of the supporting material for this paper we provide the computer program used to make the calculations, including a graphical user interface.
NASA Astrophysics Data System (ADS)
Honigmann, Michael; Liebermann, Heinz-Peter; Buenker, Robert J.
2010-07-01
The complex multireference single- and double-excitation configuration interaction method has been employed to compute potential curves for the anion of the hydrogen chloride molecule. First, conventional CI calculations with real basis functions have been carried out to determine the potential curves of both HCl and its anion over a large range of internuclear distance. It is shown that adding basis functions with very small exponents leads to sharply avoided crossings for the HCl- potentials that greatly complicate the search for resonance states thought to be responsible for features observed in electron collision experiments. By limiting the number of such diffuse-type functions it is possible to describe resonance states at a highly correlated level and still account for their interaction with the continuum in which they are embedded. In the present study of the HCl- anion the complex basis function technique of Moiseyev-Corcoran and McCurdy-Resigno is employed to calculate the energy positions and line-widths of the resonance states. Two states of Σ2+ symmetry are calculated which have potentials that have significantly different shapes than that of the neutral ground state and thus contribute to the cross section for vibrational excitation of the neutral HCl molecule induced by low-energy electron collisions. The lower of these (1 Σ2+) correlates smoothly with the bound anionic ground state at large internuclear distances and is seen to be responsible for the sharp peaks observed in the low-energy region of the spectrum. The upper state (3 Σ2+) has a much larger bond length and is assigned to the broad bands observed with a maximum in the 2.5-3.0 eV range. The present calculations thus stand in contradiction to earlier claims that the above peaks are caused by so-called virtual states without a definite autoionization lifetime.
Anharmonic densities of states: A general dynamics-based solution.
Jellinek, Julius; Aleinikava, Darya
2016-06-01
Density of states is a fundamental physical characteristic that lies at the foundation of statistical mechanics and theoretical constructs that derive from them (e.g., kinetic rate theories, phase diagrams, and others). Even though most real physical systems are anharmonic, the vibrational density of states is customarily treated within the harmonic approximation, or with some partial, often limited, account for anharmonicity. The reason for this is that the problem of anharmonic densities of states stubbornly resisted a general and exact, yet convenient and straightforward in applications, solution. Here we formulate such a solution within both classical and quantum mechanics. It is based on actual dynamical behavior of systems as a function of energy and as observed, or monitored, on a chosen time scale, short or long. As a consequence, the resulting anharmonic densities of states are fully dynamically informed and, in general, time-dependent. As such, they lay the ground for formulation of new statistical mechanical frameworks that incorporate time and are ergodic, by construction, with respect to actual dynamical behavior of systems. PMID:27276941
Anharmonic densities of states: A general dynamics-based solution
NASA Astrophysics Data System (ADS)
Jellinek, Julius; Aleinikava, Darya
2016-06-01
Density of states is a fundamental physical characteristic that lies at the foundation of statistical mechanics and theoretical constructs that derive from them (e.g., kinetic rate theories, phase diagrams, and others). Even though most real physical systems are anharmonic, the vibrational density of states is customarily treated within the harmonic approximation, or with some partial, often limited, account for anharmonicity. The reason for this is that the problem of anharmonic densities of states stubbornly resisted a general and exact, yet convenient and straightforward in applications, solution. Here we formulate such a solution within both classical and quantum mechanics. It is based on actual dynamical behavior of systems as a function of energy and as observed, or monitored, on a chosen time scale, short or long. As a consequence, the resulting anharmonic densities of states are fully dynamically informed and, in general, time-dependent. As such, they lay the ground for formulation of new statistical mechanical frameworks that incorporate time and are ergodic, by construction, with respect to actual dynamical behavior of systems.
Effect of solution saturation state and temperature on diopside dissolution
Dixit, S; Carroll, S A
2007-03-23
Steady-state dissolution rates of diopside are measured as a function of solution saturation state using a titanium flow-through reactor at pH 7.5 and temperature ranging from 125 to 175 C. Diopside dissolved stoichiometrically under all experimental conditions and rates were not dependent on sample history. At each temperature, rates continuously decreased by two orders of magnitude as equilibrium was approached and did not exhibit a dissolution plateau of constant rates at high degrees of undersaturation. The variation of diopside dissolution rates with solution saturation can be described equally well with a ion exchange model based on transition state theory or pit nucleation model based on crystal growth/dissolution theory from 125 to 175 C. At 175 C, both models over predict dissolution rates by two orders of magnitude indicating that a secondary phase precipitated in the experiments. The ion exchange model assumes the formation of a Si-rich, Mg-deficient precursor complex. Lack of dependence of rates on steady-state aqueous calcium concentration supports the formation of such a complex, which is formed by exchange of protons for magnesium ions at the surface.
Gravastar solutions with continuous pressures and equation of state
NASA Astrophysics Data System (ADS)
DeBenedictis, A.; Horvat, D.; Ilijić, S.; Kloster, S.; Viswanathan, K. S.
2006-04-01
We study the gravitational vacuum star (gravastar) configuration as proposed by Cattoen et al (2005 Class. Quantum Grav. 22 4189) in a model where the interior de Sitter spacetime segment is continuously extended to the exterior Schwarzschild spacetime. The multilayered structure of Mazur and Mottola (2001 Preprint gr-qc/0109035, 2003 Proc. 6th Workshop on Quantum Field Theory Under the Influence of External Conditions (Oklahoma) (Princeton, NJ: Rinton), Preprint gr-qc/0405111 (2004 Proc. Natl Acad. Sci. 111 9545) is replaced by a continuous stress-energy tensor at the price of introducing anisotropy in the (fluid) model of the gravastar. Either with an ansatz for the equation of state connecting the radial pr and tangential pt pressure or with a calculated equation of state with non-homogeneous energy/fluid density, solutions are obtained which in all aspects satisfy the conditions expected for an anisotropic gravastar (Cattoen et al 2005 Class. Quantum Grav. 22 4189). Certain energy conditions have been shown to be obeyed and a polytropic equation of state has been derived. Stability of the solution with respect to possible axial perturbation is shown to hold.
Flash photolysis and triplet states and free radicals in solution.
Windsor, Maurice W
2003-05-01
A personal account is given of the development of microsecond flash photolysis in George Porter's laboratory at Cambridge in the early 1950s. This made possible, for the first time, the observation of the absorption spectra of the lowest triplet states of many polycyclic aromatic hydrocarbons in fluid solutions. The T-T transitions were found to be very intense with oscillator strengths approaching unity in many cases. Detailed kinetic studies showed that triplet state decay was first order and viscosity dependent and strongly quenched by dissolved oxygen. Several aromatic free radicals such as benzyl were also observed in liquid solution for the first time. The advent of the laser in the early 1960s made it possible to extend flash photolysis studies to the ns and ps and eventually the fs time range. Such studies have revolutionized the study of excited states and free radicals and have made possible advances in the understanding of the dynamics of chemical and biological systems that would have been unimaginable 60 years ago. PMID:12803067
Steady-State Solution of a Flexible Wing
NASA Technical Reports Server (NTRS)
Karkehabadi, Reza; Chandra, Suresh; Krishnamurthy, Ramesh
1997-01-01
A fluid-structure interaction code, ENSAERO, has been used to compute the aerodynamic loads on a swept-tapered wing. The code has the capability of using Euler or Navier-Stokes equations. Both options have been used and compared in the present paper. In the calculation of the steady-state solution, we are interested in knowing how the flexibility of the wing influences the lift coefficients. If the results of a flexible wing are not affected by the flexibility of the wing significantly, one could consider the wing to be rigid and reduce the problem from fluid-structure interaction to a fluid problem.
Ground state solutions for non-autonomous fractional Choquard equations
NASA Astrophysics Data System (ADS)
Chen, Yan-Hong; Liu, Chungen
2016-06-01
We consider the following nonlinear fractional Choquard equation, {(‑Δ)su+u=(1+a(x))(Iα ∗ (|u| p))|u| p‑2uin RN,u(x)→0as |x|→∞, here s\\in (0,1) , α \\in (0,N) , p\\in ≤ft[2,∞ \\right) and \\frac{N-2s}{N+α}<\\frac{1}{p}<\\frac{N}{N+α} . Assume {{\\lim}|x|\\to ∞}a(x)=0 and satisfying suitable assumptions but not requiring any symmetry property on a(x), we prove the existence of ground state solutions for (0.1).
Federal Register 2010, 2011, 2012, 2013, 2014
2011-01-18
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Complex formation between excited-state saturated amines and water in n-hexane solution
Halpern, A.M.; Ruggles, C.J.; Zhang, X.K.
1987-06-10
Fluorescence spectra and decay curves of dilute solutions (<3 x 10/sup -4/ M) of triethylamine (TEA), tri-n-propylamine (TPA), and 1,4-diazabicyclo(2.2.2)octane (DABCO) in H/sub 2/O- and D/sub 2/O-saturated n-hexane reveal the presence of a complex formed between the electronically excited amine and water. The decay curves, measured between 273 and 323 K (and at 280 and 360 nm; 300 and 400 nm for DABCO), conform to the standard monomer-excimer photokinetic scheme and are analyzed accordingly. These results indicate that the binding energy of the excited TEA-H/sub 2/O complex (B*) is ca. 7.8 kcal/mol, which is larger than that of the ground-state TEA hydrate. B* for the TPA and DABCO-H/sub 2/O complexes is estimated to be ca. 10 and 8.8 kcal/mol, respectively. Stationary-state measurements are consistent with these assignments. The activation energy for the diffusion of water in n-hexane (assumed to be monomeric) appears to be very small (<1 kcal/mol). The decay constants of the three complexes studied are ca. 3.4 x 10/sup 7/ s/sup -1/ for amine-H/sub 2/O and 2.9 x 10/sup 7/ s/sup -1/ for the amine-D/sub 2/O systems. Intrinsic fluorescence quantum efficiencies of the amine-H/sub 2/O complexes are 0.17, 0.23, and 0.28 for TEA, TPA, and DABCO, respectively, at 303 K. A Foerster cycle analysis of the dry and H/sub 2/O-saturated fluorescence spectra of TEA, when taking the ground-state hydrate into account indicates that the repulsion energy of the post-fluorescence (TEA-H/sub 2/O) complex is ca. 10 kcal/mol.
Multiphoton Absorption of Myoglobin Nitric-Oxide complex: Relaxation by D-NEMD of a Stationary State
Cottone, Grazia; Lattanzi, Gianluca; Ciccotti, Giovanni; Elber, Ron
2012-01-01
The photodissociation and geminate recombination of nitric oxide in myoglobin, under continuous illumination, is modeled computationally. The relaxation of the photon energy into the protein matrix is also considered in a single simulation scheme that mimics a complete experimental setup. The dynamic approach to Non Equilibrium Molecular Dynamics is used, starting from a steady state, to compute its relaxation to equilibrium. Simulations are conducted for the native form of sperm whale myoglobin and for two other mutants, V68W and L29F, illustrating a fair diversity of spatial and temporal geminate recombination processes. Energy flow to the heme and immediate protein environment provide hints to allostery. In particular a pathway of energy flow between the heme and the FG loop is illustrated. Although the simulations were conducted for myoglobin only, the thermal fluctuations of the FG corner are in agreement with the large structural shifts of FG during the allosteric transition of tetrameric hemoglobin. PMID:22356468
NASA Astrophysics Data System (ADS)
Moulds, Rebecca J.; Buntine, Mark A.; Lawrance, Warren D.
2004-09-01
The potential energy surfaces of the van der Waals complexes benzene-Ar and p-difluorobenzene-Ar have been investigated at the second-order Møller-Plesset (MP2) level of theory with the aug-cc-pVDZ basis set. Calculations were performed with unconstrained geometry optimization for all stationary points. This study has been performed to elucidate the nature of a conflict between experimental results from dispersed fluorescence and velocity map imaging (VMI). The inconsistency is that spectra for levels of p-difluorobenzene-Ar and -Kr below the dissociation thresholds determined by VMI show bands where free p-difluorobenzene emits, suggesting that dissociation is occurring. We proposed that the bands observed in the dispersed fluorescence spectra are due to emission from states in which the rare gas atom orbits the aromatic chromophore; these states are populated by intramolecular vibrational redistribution from the initially excited level [S. M. Bellm, R. J. Moulds, and W. D. Lawrance, J. Chem. Phys. 115, 10709 (2001)]. To test this proposition, stationary points have been located on both the benzene-Ar and p-difluorobenzene-Ar potential energy surfaces (PESs) to determine the barriers to this orbiting motion. Comparison with previous single point CCSD(T) calculations of the benzene-Ar PES has been used to determine the amount by which the barriers are overestimated at the MP2 level. As there is little difference in the comparable regions of the benzene-Ar and p-difluorobenzene-Ar PESs, the overestimation is expected to be similar for p-difluorobenzene-Ar. Allowing for this overestimation gives the barrier to movement of the Ar atom around the pDFB ring via the valley between the H atoms as ⩽204 cm-1 in S0 (including zero point energy). From the estimated change upon electronic excitation, the corresponding barrier in S1 is estimated to be ⩽225 cm-1. This barrier is less than the 240 cm-1 energy of 302¯, the vibrational level for which the anomalous "free p
Probing protein hydration and conformational states in solution.
Reid, C; Rand, R P
1997-01-01
The addition of polyethylene glycol (PEG), of various molecular weights, to solutions bathing yeast hexokinase increases the affinity of the enzyme for its substrate glucose. The results can be interpreted on the basis that PEG acts directly on the protein or indirectly through water activity. The nature of the effects suggests to us that PEG's action is indirect. Interpretation of the results as an osmotic effect yields a decrease in the number of water molecules, delta Nw, associated with the glucose binding reaction. delta Nw is the difference in the number of PEG-inaccessible water molecules between the glucose-bound and glucose-free conformations of hexokinase. At low PEG concentrations, delta Nw increases from 50 to 326 with increasing MW of the PEG from 300 to 1000, and then remains constant for MW-PEG up to 10,000. This suggests that up to MW 1000, solutes of increasing size are excluded from ever larger aqueous compartments around the protein. Three hundred and twenty-six waters is larger than is estimated from modeling solvent volumes around the crystal structures of the two hexokinase conformations. For PEGs of MW > 1000, delta Nw falls from 326 to about 25 waters with increasing PEG concentration, i.e., PEG alone appears to "dehydrate" the unbound conformation of hexokinase in solution. Remarkably, the osmotic work of this dehydration would be on the order of only one k T per hexokinase molecule. We conclude that under thermal fluctuations, hexokinase in solution has a conformational flexibility that explores a wide range of hydration states not seen in the crystal structure. Images FIGURE 1 FIGURE 11 PMID:9138553
NASA Astrophysics Data System (ADS)
Rassi, Erik M.; Codd, Sarah L.; Seymour, Joseph D.
2011-01-01
Flow in porous media and the resultant hydrodynamics are important in fields including but not limited to the hydrology, chemical, medical and petroleum industries. The observation and understanding of the hydrodynamics in porous media are critical to the design and optimal utilization of porous media, such as those seen in trickle-bed reactors, medical filters, subsurface flows and carbon sequestration. Magnetic resonance (MR) provides for a non-invasive technique that can probe the hydrodynamics on pore and bulk scale lengths; many previous works have characterized fully saturated porous media, while rapid MR imaging (MRI) methods in particular have previously been applied to partially saturated flows. We present time- and ensemble-averaged MR measurements to observe the effects on a bead pack partially saturated with air under flowing water conditions. The 10 mm internal diameter bead pack was filled with 100 μm borosilicate glass beads. Air was injected into the bead pack as water flowed simultaneously through the sample at 25 ml h-1. The initial partially saturated state was characterized with MRI density maps, free induction decay (FID) experiments, propagators and velocity maps before the water flow rate was increased incrementally from 25 to 500 ml h-1. After the maximum flow rate of 500 ml h-1, the MRI density maps, FID experiments, propagators and velocity maps were repeated and compared to the data taken before the maximum flow rate. This work shows that a partially saturated single-phase flow has global flow dynamics that return to characteristic flow statistics once a steady-state high flow rate has been reached. This high flow rate pushed out a significant amount of the air in the bead pack and caused the return of a preferential flow pattern. Velocity maps indicated that local flow statistics were not the same for the before and after blow out conditions. It has been suggested and shown previously that a flow pattern can return to
TOPICAL REVIEW Electronic states of graphene nanoribbons and analytical solutions
NASA Astrophysics Data System (ADS)
Wakabayashi, Katsunori; Sasaki, Ken-ichi; Nakanishi, Takeshi; Enoki, Toshiaki
2010-10-01
Graphene is a one-atom-thick layer of graphite, where low-energy electronic states are described by the massless Dirac fermion. The orientation of the graphene edge determines the energy spectrum of π-electrons. For example, zigzag edges possess localized edge states with energies close to the Fermi level. In this review, we investigate nanoscale effects on the physical properties of graphene nanoribbons and clarify the role of edge boundaries. We also provide analytical solutions for electronic dispersion and the corresponding wavefunction in graphene nanoribbons with their detailed derivation using wave mechanics based on the tight-binding model. The energy band structures of armchair nanoribbons can be obtained by making the transverse wavenumber discrete, in accordance with the edge boundary condition, as in the case of carbon nanotubes. However, zigzag nanoribbons are not analogous to carbon nanotubes, because in zigzag nanoribbons the transverse wavenumber depends not only on the ribbon width but also on the longitudinal wavenumber. The quantization rule of electronic conductance as well as the magnetic instability of edge states due to the electron-electron interaction are briefly discussed.
Steady state solutions to dynamically loaded periodic structures
NASA Technical Reports Server (NTRS)
Kalinowski, A. J.
1980-01-01
The general problem of solving for the steady state (time domain) dynamic response (i.e., NASTRAN rigid format-8) of a general elastic periodic structure subject to a phase difference loading of the type encountered in traveling wave propagation problems was studied. Two types of structural configurations were considered; in the first type, the structure has a repeating pattern over a span that is long enough to be considered, for all practical purposes, as infinite; in the second type, the structure has structural rotational symmetry in the circumferential direction. The theory and a corresponding set of DMAP instructions which permits the NASTRAN user to automatically alter the rigid format-8 sequence to solve the intended class of problems are presented. Final results are recovered as with any ordinary rigid format-8 solution, except that the results are only printed for the typical periodic segment of the structure. A simple demonstration problem having a known exact solution is used to illustrate the implementation of the procedure.
NEXAFS Chemical State and Bond Lengths of p-Aminobenzoic Acid in Solution and Solid State
NASA Astrophysics Data System (ADS)
Stevens, J. S.; Gainar, A.; Suljoti, E.; Xiao, J.; Golnak, R.; Aziz, E. F.; Schroeder, S. L. M.
2016-05-01
Solid-state and solution pH-dependent NEXAFS studies allow direct observation of the electronic state of para-aminobenzoic acid (PABA) as a function of its chemical environment, revealing the chemical state and bonding of the chemical species. Variations in the ionization potential (IP) and 1s→π* resonances unequivocally identify the chemical species (neutral, cationic, or anionic) present and the varying local environment. Shifts in σ* shape resonances relative to the IP in the NEXAFS spectra vary with C-N bond length, and the important effect of minor alterations in bond length is confirmed with nitrogen FEFF calculations, leading to the possibility of bond length determination in solution.
Extraction of stationary components in biosignal discrimination.
Martinez-Vargas, J D; Cardenas-Pena, D; Castellanos-Dominguez, G
2012-01-01
Biosignal recordings are widely used in the medical environment to support the evaluation and the diagnosis of pathologies. Nevertheless, the main difficulty lies in the non-stationary behavior of the biosignals, difficulting the obtention of patterns characterizing the changes in physiological or pathological states. Thus, the obtention of the stationary and non-stationary components of a biosignal is still an open issue. This work proposes a methodology to detect time-homogeneities based on time-frequency analysis with aim to extract the non-stationary behavior of the biosignal. Results show an increase in the stationarity and in the distance between classes of the reconstructions from the enhanced time-frequency representations. The stationary components extracted with the proposed approach can be used to solve biosignal classification problems. PMID:23365817
NASA Astrophysics Data System (ADS)
Manard, Benjamin T.; Marcus, R. Kenneth
2012-08-01
Capillary-channeled polymer (C-CP) fibers are employed in a micropipette tip format to affect a stationary phase for the solid phase extraction (SPE) of proteins from buffer solutions prior to MALDI-MS analysis. Proteins readily adsorb to the polypropylene (PP) C-CP fibers while buffer species are easily washed off the tips using DI-H2O. Elution of the solutes is achieved with an aliquot of 50:50 ACN:H2O, which is compatible with the subsequent spotting on the MALDI target with the matrix solution. Lysozyme and cytochrome c are used as test species, with a primary buffer composition of 100 mM Tris-HCl. In this case, direct MALDI-MS produces no discernible protein signals. SPE on the C-CP fibers yields high fidelity mass spectra for 1 μL sample volumes. Limits of detection for cytochrome c in 100 mM Tris-HCl are on the order of 40 nM. Extraction of cytochrome c from buffer concentrations of up to 1 M Tris-HCl, provides signal recoveries that are suppressed by only ~50 % versus neat protein solutions. Finally, extraction of 3.1 μM cytochrome c from a synthetic urine matrix exhibits excellent recovery.
States leverage telepsychiatry solutions to ease ED crowding, accelerate care.
2015-02-01
Many states are having success turning to telepsychiatry-based solutions to connect mental health patients with needed care while also decompressing crowded EDs. Just one year into a statewide telepsychiatry initiative in North Carolina (NC-STeP), administrators say the approach has saved as much as $7 million, and hospital demand for the service is higher than anticipated. In Texas, mental health emergency centers (MHEC) that use telepsychiatry to connect patients in rural areas with needed psychiatric care are freeing up EDs to focus on medical care. In just 11 months, 91 North Carolina hospitals have at least started the process to engage in NC-STeP. Much of the savings from NC-STeP come from involuntary commitment orders being overturned as a result of the telepsychiatry consults, reducing the need for expensive inpatient care. Implementing NC-STeP has involved multiple hurdles including credentialing difficulties and technical/firewall challenges. The Texas model provides 24/7 availability of psychiatrists via telemedicine through a network of MHECs. In-person staff at the MHECs perform basic screening tests and blood draws so that medical clearance can be achieved without the need for an ED visit in most cases. Funding for the MHECs comes from the state, hospitals in the region, and local governmental authorities that reap savings or benefits from the initiative. PMID:25688413
Extended law of corresponding states for protein solutions.
Platten, Florian; Valadez-Pérez, Néstor E; Castañeda-Priego, Ramón; Egelhaaf, Stefan U
2015-05-01
The so-called extended law of corresponding states, as proposed by Noro and Frenkel [J. Chem. Phys. 113, 2941 (2000)], involves a mapping of the phase behaviors of systems with short-range attractive interactions. While it has already extensively been applied to various model potentials, here we test its applicability to protein solutions with their complex interactions. We successfully map their experimentally determined metastable gas-liquid binodals, as available in the literature, to the binodals of short-range square-well fluids, as determined by previous as well as new Monte Carlo simulations. This is achieved by representing the binodals as a function of the temperature scaled with the critical temperature (or as a function of the reduced second virial coefficient) and the concentration scaled by the cube of an effective particle diameter, where the scalings take into account the attractive and repulsive contributions to the interaction potential, respectively. The scaled binodals of the protein solutions coincide with simulation data of the adhesive hard-sphere fluid. Furthermore, once the repulsive contributions are taken into account by the effective particle diameter, the temperature dependence of the reduced second virial coefficients follows a master curve that corresponds to a linear temperature dependence of the depth of the square-well potential. We moreover demonstrate that, based on this approach and cloud-point measurements only, second virial coefficients can be estimated, which we show to agree with values determined by light scattering or by Derjaguin-Landau-Verwey-Overbeek (DLVO)-based calculations. PMID:25956118
Solid state lighting for the developing world: the only solution
NASA Astrophysics Data System (ADS)
Peon, Rudolfo; Doluweera, Ganesh; Platonova, Inna; Irvine-Halliday, Dave; Irvine-Halliday, Gregor
2005-09-01
Approximately two billion people, one third of humanity still has no access to electricity, and thus relies on fuel-based lighting, a dangerous alternative of last resort that is unhealthy, expensive, and offers very poor levels of illumination. This lack of light makes it difficult to perform most evening activities including studies by children and adults alike and therefore represents a significant barrier to human development. Over the past five years The Light Up The World Foundation (LUTW) has pioneered the use of the white light emitting diode (WLED) as an alternative home lighting solution, bringing clean, affordable light to thousands of non-electrified homes around the world. The information presented herein is intended to increase awareness of the enormous potential possessed by this emergent technology, "Solid State Lighting" (SSL), to improve the quality of life of millions of people around the world. The feasibility of its implementation is demonstrated with results from comprehensive field experience and laboratory research work. The mutual economic, social and environmental benefits for both stakeholders and SSL suppliers are discussed. Strategies conducive to the dissemination of this technology throughout the developing world are also presented.
Nuclear magnetic resonance in water solutions of inorganic salts in vitreous and liquid states
Lundin, A. G. Koryavko, N. A.; Chichikov, S. A.
2013-05-15
Peculiarities of the behavior of water solutions of inorganic salts at temperatures of {approx}(120-150) K are examined. At these temperatures the solutions are in the vitreous state. At higher temperatures (up to 240 K) the solutions may be in metastable liquid, crystalline, or usual liquid states.
Asymptotic Steady-state Solution to a Bow Shock with an Infinite Mach Number
NASA Astrophysics Data System (ADS)
Yalinewich, Almog; Sari, Re’em
2016-08-01
The problem of a cold gas flowing past a stationary obstacle is considered. We study the bow shock that forms around the obstacle and show that at large distances from the obstacle the shock front forms a parabolic solid of revolution. The profiles of the hydrodynamic variables in the interior of the shock are obtained by solution of the hydrodynamic equations in parabolic coordinates. The results are verified with a hydrodynamic simulation. The drag force on the obstacle is also calculated. Finally, we use these results to model the bow shock around an isolated neutron star.
Complete solution for unambiguous discrimination of three pure states with real inner products
Sugimoto, H.; Hashimoto, T.; Horibe, M.; Hayashi, A.
2010-09-15
Complete solutions are given in a closed analytic form for unambiguous discrimination of three general pure states with real mutual inner products. For this purpose, we first establish some general results on unambiguous discrimination of n linearly independent pure states. The uniqueness of solution is proved. The condition under which the problem is reduced to an (n-1)-state problem is clarified. After giving the solution for three pure states with real mutual inner products, we examine some difficulties in extending our method to the case of complex inner products. There is a class of set of three pure states with complex inner products for which we obtain an analytical solution.
Solutions of the Noh Problem for Various Equations of State Using Lie Groups
Axford, R.A.
1998-08-01
A method for developing invariant equations of state for which solutions of the Noh problem will exist is developed. The ideal gas equation of state is shown to be a special case of the general method. Explicit solutions of the Noh problem in planar, cylindrical and spherical geometry are determined for a Mie-Gruneisen and the stiff gas equation of state.
Chiang, Chao-Ching; Su, Chien-You; Yang, An-Chih; Wang, Ting-Yu; Lee, Wen-Ya; Hua, Chi-Chung; Kang, Dun-Yen
2016-07-27
This paper reports on the fabrication of low-k (amorphous) silica thin films cast from solutions without and with two different types of surfactants (TWEEN® 80 and Triton™ X-100) to elucidate the relationships between the structural/morphological features of the casting solutions and the physical properties of the resulting thin films. Cryogenic transmission microscopy (cryo-TEM), static/dynamic light scattering (SLS/DLS), and small-angle X-ray scattering (SAXS) revealed contrasting colloidal dispersion states and phase behavior among the three casting solutions. Casting solution with the Triton™ X-100 surfactant produced stable (>90 days) nanoparticles with good dispersion in solution (mean particle size ∼10 nm) as well as good mesopore volume (characterized by nitrogen physisorption) in powder and thin films of high mechanical strength (characterized by the nanoindentation test). The longer main chain and bulkier side units of the TWEEN® 80 surfactant led to stable micelle-nanoparticle coexisting dispersion, which resulted in the highest mesopore volume in powder and thin films with the lowest dielectric constant (∼3) among the samples in this study. The casting solution without the surfactant failed to produce a stabilized solution or thin films of acceptable uniformity. These findings demonstrate the possibility of fine-tuning low-k silica film properties by controlling the colloidal state of casting solutions. PMID:27401818
Simonsson, Ivar; Mostad, Petter
2016-07-01
Probability calculations for relationship inference based on DNA tests are often performed with computer packages such as Familias. When mutations are assumed to be a possibility, one may notice a curious and problematic effect of including untested parents: results tend to change slightly. In this paper, we trace this effect back to fundamental model-formulating issues which can only be resolved by using stationary mutation models. We present several methods for obtaining such stationary mutation matrices from original mutation matrices, and evaluate essential properties of these methods. Our conclusion is that typically, stationary mutation models can be obtained, but for many types of markers, it may be impossible to combine specific biologically reasonable requirements for a mutation matrix with the requirement of stationarity. PMID:27231805
Controlling Molecular Ordering in Solution-State Conjugated Polymers
Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; Hong, Kunlun; Bonnesen, Peter V.; Sumpter, Bobby G.; Smith, Gregory Scott; Ivanov, Ilia N.; Do, Changwoo
2015-07-17
Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.
Controlling molecular ordering in solution-state conjugated polymers
NASA Astrophysics Data System (ADS)
Zhu, J.; Han, Y.; Kumar, R.; He, Y.; Hong, K.; Bonnesen, P. V.; Sumpter, B. G.; Smith, S. C.; Smith, G. S.; Ivanov, I. N.; Do, C.
2015-09-01
Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.Rationally encoding molecular interactions that can control the assembly structure and functional expression in a solution of conjugated polymers hold great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with the desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution, we demonstrate that both chain conformation and degree of molecular ordering
NASA Astrophysics Data System (ADS)
Pan, Li-Hua; Hou, Peng-Fei; Chen, Jia-Yun
2016-08-01
The 2D steady-state solutions regarding the expressions of stress and strain for fluid-saturated, orthotropic, poroelastic plane are derived in this paper. For this object, the general solutions of the corresponding governing equation are first obtained and expressed in harmonic functions. Based on these compact general solutions, the suitable harmonic functions with undetermined constants for line fluid source in the interior of infinite poroelastic body and a line fluid source on the surface of semi-infinite poroelastic body are presented, respectively. The fundamental solutions can be obtained by substituting these functions into the general solution, and the undetermined constants can be obtained by the continuous conditions, equilibrium conditions and boundary conditions.
Instability of stationary liquid sheets.
Ardekani, A M; Joseph, D D
2009-03-31
The rupture of a 3D stationary free liquid film under the competing effects of surface tension and van der Waals forces is studied as a linearized stability problem in a purely irrotational analysis utilizing the dissipation method. The results of the foregoing analysis are compared with a 2D long-wave approximation that has given rise to an extensive literature on the rupture problem. The irrotational and long-wave approximations are here compared with the exact 2D solution. The exact solution and the two approximate theories give the same results for infinitely long waves. The problem considered depends on two dimensionless parameters, the Hamaker number and the Ohnesorge number. The Hamaker number is a dimensionless number defined as a measure of the ratio of van der Waals forces to surface tension. The exact solution and the two approximate solutions differ by < 1% when the Hamaker number is small for all values of the Ohnesorge number. When the Ohhnesorge number is close to one, as in the case of water films separated by distance 100 A, the long-wave approximation overestimates and the potential flow approximation underestimates the exact solution by similar small amounts. The high accuracy of the dissipation method shows that the effects of vorticity are small for small to moderate Hamaker numbers. PMID:19279213
Stationary nonlinear Alfven waves and solitons
NASA Technical Reports Server (NTRS)
Hada, T.; Kennel, C. F.; Buti, B.
1989-01-01
Stationary solutions of the derivative nonlinear Schroedinger equation are discussed and classified by using a pseudopotential formulation. The solutions consist of a rich family of nonlinear Alfven waves and solitons with parallel and oblique propagation directions. Expressions for the envelope and the phase of nonlinear waves with periodic envelope modulation, and 'hyperbolic' and 'algebraic' solitons are given. The propagation angle for the slightly modulated elliptic, periodic waves and for oblique solitons is evaluated.
Stationary phase in the yeast Saccharomyces cerevisiae.
Werner-Washburne, M; Braun, E; Johnston, G C; Singer, R A
1993-01-01
Growth and proliferation of microorganisms such as the yeast Saccharomyces cerevisiae are controlled in part by the availability of nutrients. When proliferating yeast cells exhaust available nutrients, they enter a stationary phase characterized by cell cycle arrest and specific physiological, biochemical, and morphological changes. These changes include thickening of the cell wall, accumulation of reserve carbohydrates, and acquisition of thermotolerance. Recent characterization of mutant cells that are conditionally defective only for the resumption of proliferation from stationary phase provides evidence that stationary phase is a unique developmental state. Strains with mutations affecting entry into and survival during stationary phase have also been isolated, and the mutations have been shown to affect at least seven different cellular processes: (i) signal transduction, (ii) protein synthesis, (iii) protein N-terminal acetylation, (iv) protein turnover, (v) protein secretion, (vi) membrane biosynthesis, and (vii) cell polarity. The exact nature of the relationship between these processes and survival during stationary phase remains to be elucidated. We propose that cell cycle arrest coordinated with the ability to remain viable in the absence of additional nutrients provides a good operational definition of starvation-induced stationary phase. PMID:8393130
1980-03-01
The first portion of the Conceptual Design Study of Stirling Engines for Stationary Power Application in the 500 to 3000 hp range which was aimed at state-of-the-art stationary Stirling engines for a 1985 hardware demonstration is summarized. The main goals of this effort were to obtain reliable cost data for a stationary Stirling engine capable of meeting future needs for total energy/cogeneration sysems and to establish a pragmatic and conservative base design for a first generation hardware. Starting with an extensive screening effort, 4 engine types, i.e., V-type crank engine, radial engine, swashplate engine, and rhombic drive engine, and 3 heat transport systems, i.e., heat pipe, pressurized gas heat transport loop, and direct gas fired system, were selected. After a preliminary layout cycle, the rhombic drive engine was eliminated due to intolerable maintenance difficulties on the push rod seals. V, radial and swashplate engines were taken through a detailed design/layout cycle, to establish all important design features and reliable engine weights. After comparing engine layouts and analyzing qualitative and quantitative evaluation criteria, the V-crank engine was chosen as the candidate for a 1985 hardware demonstration.
Controlling Molecular Ordering in Solution-State Conjugated Polymers
Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; Hong, Kunlun; Bonnesen, Peter V.; Sumpter, Bobby G.; Smith, Gregory Scott; Ivanov, Ilia N.; Do, Changwoo
2015-07-17
Rationally encoding molecular interactions that can control the assembly structure and functional expression in solution of conjugated polymers holds great potential for enabling optimal organic optoelectronic and sensory materials. In this work, we show that thermally-controlled and surfactant-guided assembly of water-soluble conjugated polymers in aqueous solution is a simple and effective strategy to generate optoelectronic materials with desired molecular ordering. We have studied a conjugated polymer consisting of a hydrophobic thiophene backbone and hydrophilic, thermo-responsive ethylene oxide side groups, which shows a step-wise, multi-dimensional assembly in water. By incorporating the polymer into phase-segregated domains of an amphiphilic surfactant in solution,more » we demonstrate that both chain conformation and degree of molecular ordering of the conjugated polymer can be tuned in hexagonal, micellar and lamellar phases of the surfactant solution. The controlled molecular ordering in conjugated polymer assembly is demonstrated as a key factor determining the electronic interaction and optical function.« less
Is State-Mandated Redesign an Effective and Sustainable Solution?
ERIC Educational Resources Information Center
Young, Michelle D.
2013-01-01
There is a pervasive and ongoing perception that leadership preparation is a problem. Important questions remain about the intentions, capacity, and impact of state departments of education engaged in leadership preparation program redesign. In this essay, I take up several issues concerning this state policy work, including whether a one size…
The use of series-solutions for batch and sequential estimation. [of nonlinear spacecraft state
NASA Technical Reports Server (NTRS)
Feagin, T.; Mikkilineni, R. P.
1975-01-01
Iterative methods for the approximate solution of the nonlinear state estimation problem are investigated in which the solution is retained in the form of a finite series of Chebyshev polynomials. Algorithms are presented which allow the state to be estimated from observational data in either the batch or the sequential form. The advantages of these techniques are discussed.
HYDROCARBON POLLUTANTS FROM STATIONARY SOURCES
The report gives results of a study of hydrocarbon pollutants from stationary sources. Early in the study, readily available information was assembled on stationary sources of hydrocarbon emissions and effluents. Information was also obtained on process descriptions, operating pa...
Neef, M; Kruse, K
2014-11-01
We study the dynamics of an active polar fluid in the interstitial space between two fixed coaxial cylinders. For sufficiently large expansive or contractive active stresses, the fluid presents roll instabilities of axially symmetric states leading to the spontaneous formation of vortices in the flow field. These vortices are either stationary or travel around the inner cylinder. Increasing the activity further, our numerical solutions indicate the existence of active turbulence that coexists with regular vortex solutions. PMID:25493812
Relaminarization under stationary vortices
NASA Astrophysics Data System (ADS)
Breidenthal, Robert
2005-11-01
Flow visualization reveals that a turbulent boundary layer is relaminarized when stationary streamwise vortices are introduced. Following a suggestion of Balle, the vortices are stabilized by large streamwise ``Karman'' grooves in a wavy wall. In a water tunnel, upstream vortex generators place a large streamwise vortex in the middle of each groove, at the stationary point where Prandtl's vortex force vanishes. According to a theory by Cotel, the wall fluxes of a turbulent boundary layer should decline to laminar values under such ``persistent'' vortices. The observed relaminarization is consistent with this theory and with previous measurements of heat transfer by Touel and Balle. However, the structure of the transverse flow resembles the cats-eye pattern of a temporal shear layer rather than the anticipated von Karman wake. The cats-eye pattern corresponds to the forced shear layers of Oster-Wygnanski and Roberts, who found that the Reynolds stresses and mixing rate also decline to laminar values.
NASA Astrophysics Data System (ADS)
Kvitko, Alexander
2016-06-01
By constructing a Luenberger-type asymptotic observer, a method of finding the control function, that ensures the translation of a class of nonlinear stationary control systems of ordinary differential equations from the initial state to a given final state taking into account the actual measured values, was developed. A constructive criterion guaranteeing the existence of solution of this problem was found. An algorithm is proposed for constructing a control function that transfer wide class of nonlinear systems of ordinary differential equations from an initial state to an fixed state. The algorithm is convenient for numerical implementation. A constructive condition is obtained for which this transfer is possible.
State-based coverage solutions: the California Health Benefit Exchange.
Weinberg, Micah; Haase, Leif Wellington
2011-05-01
California was the first state to create its own health insurance exchange after the passage of the Affordable Care Act. Because of its front-runner status and the sheer size of its coverage expansion, California's choices will have implications for other states as they address difficult issues, including minimizing adverse selection, promoting cost-conscious consumer choice, and seamlessly coordinating with public programs. California took advantage of the flexibility in the federal health reform law to create an exchange that will function as an active purchaser in the marketplace; take significant steps to combat adverse selection both against and within the exchange, including requiring all insurers to sell all tiers of products and making exchange participation a condition of selling catastrophic plans; and allow community-based health plans to develop commercial offerings for the exchange. This brief examines these decisions, which will provide a roadmap for other states as they set up their exchanges. PMID:21630546
Arbitrary Steady-State Solutions with the K-epsilon Model
NASA Technical Reports Server (NTRS)
Rumsey, Christopher L.; Pettersson Reif, B. A.; Gatski, Thomas B.
2006-01-01
Widely-used forms of the K-epsilon turbulence model are shown to yield arbitrary steady-state converged solutions that are highly dependent on numerical considerations such as initial conditions and solution procedure. These solutions contain pseudo-laminar regions of varying size. By applying a nullcline analysis to the equation set, it is possible to clearly demonstrate the reasons for the anomalous behavior. In summary, the degenerate solution acts as a stable fixed point under certain conditions, causing the numerical method to converge there. The analysis also suggests a methodology for preventing the anomalous behavior in steady-state computations.
Back to the future: stationary source testing for fine PM
Ron Myers
2006-04-15
Decisions will be necessary concerning the most appropriate stationary source test methodologies for continuing our efforts to clean up the atmosphere. In many regions of the United States, existing methods to measure stationary source pollutant emissions may be acceptable for the foreseeable future. However, other regions will require more comprehensive source measurement methods that expand the measured pollutants to include the full range of the atmospheric burden. Decisions about which path(s) to follow will depend on existing ambient air quality levels an the need to better quantify atmospheric emissions of primary PM from stationary sources, control stationary source primary PM to achieve the ambient air quality standard, and better understand the components of stationary source primary PM emissions. This article focuses on quantifying fine PM emissions from stationary sources, including Method 5B for utility plants. 24 refs., 1 tab.
Stationary light in cold-atomic gases
Nikoghosyan, Gor; Fleischhauer, Michael
2009-07-15
We discuss stationary light created by a pair of counterpropagating control fields in {lambda}-type atomic gases with electromagnetically induced transparency for the case of negligible Doppler broadening. In this case, the secular approximation used in the discussion of stationary light in hot vapors is no longer valid. We discuss the quality of the effective light-trapping system and show that in contrast to previous claims it is finite even for vanishing ground-state dephasing. The dynamics of the photon loss is in general nonexponential and can be faster or slower than in hot gases.
Qualitative analysis of stationary Keller-Segel chemotaxis models with logistic growth
NASA Astrophysics Data System (ADS)
Wang, Qi; Yan, Jingda; Gai, Chunyi
2016-06-01
We study the stationary Keller-Segel chemotaxis models with logistic cellular growth over a one-dimensional region subject to the Neumann boundary condition. We show that nonconstant solutions emerge in the sense of Turing's instability as the chemotaxis rate {χ} surpasses a threshold number. By taking the chemotaxis rate as the bifurcation parameter, we carry out bifurcation analysis on the system to obtain the explicit formulas of bifurcation values and small amplitude nonconstant positive solutions. Moreover, we show that solutions stay strictly positive in the continuum of each branch. The stabilities of these steady-state solutions are well studied when the creation and degradation rate of the chemical is assumed to be a linear function. Finally, we investigate the asymptotic behaviors of the monotone steady states. We construct solutions with interesting patterns such as a boundary spike when the chemotaxis rate is large enough and/or the cell motility is small.
Jankowski, K.; Kowalski, K.; Jankowski, P.
1995-03-05
Single-reference coupled-cluster (SR-CC) methods parametrized with respect to four alternative reference-state configurations and orbital sets are applied to the simple H4 model system in which the degree of quasi-degeneracy of the electronic states can be varied in a wide range. Both the ground state and 10 excited states are considered with the aim of numerically studying the attainability and properties of multiple solutions of the system of nonlinear equations for the cluster amplitudes. Comparisons of up to four alternative descriptions of a given state in terms of various solutions of the SR-CC equations are made. It is found that for some excited states different parametrizations yield very close results and that the classification of the solutions into standard and nonstandard ones may not be straightforward. 15 refs., 12 tabs.
Correspondence between physical states and solutions to the coupled-cluster equations
Jankowski, K.; Kowalski, K; Grabowski, I.; Monkhorst, H.J.
1999-12-01
To discuss the usefulness of the entries of the complete set of solutions to approximate coupled-cluster (CC) equations for the description of the states of many-electron systems, one has to be able to establish a correspondence between the states and solutions. The authors have explored four methods of finding links between the states (represented for the model by the full configuration interaction wave functions and energies) and solutions to the CC equations. Numerical studies for the P4 model, which belongs to the simplest realistic many-electron model systems, show that the states-solutions correspondence pattern strongly depends on the method employed. Only for a few states all methods considered have assigned the same solutions. Among these states are those that are energetically the closest to the reference determinants. For the remaining states the assignment is not unique and the accuracy of description depends on the physical features considered. The article is concluded with a comparison of the present results and results of the most recent studies on the structure of the complete sets of solutions to the CC equations with the findings and intuitions being the content of the work by Zivkovic and Monkhorst (J Math Phys 1978, 19, 1007).
Finite element solution of optimal control problems with state-control inequality constraints
NASA Technical Reports Server (NTRS)
Bless, Robert R.; Hodges, Dewey H.
1992-01-01
It is demonstrated that the weak Hamiltonian finite-element formulation is amenable to the solution of optimal control problems with inequality constraints which are functions of both state and control variables. Difficult problems can be treated on account of the ease with which algebraic equations can be generated before having to specify the problem. These equations yield very accurate solutions. Owing to the sparse structure of the resulting Jacobian, computer solutions can be obtained quickly when the sparsity is exploited.
2015-06-01
This fact sheet describes opportunities for interested stationary fuel cell developers and end users to participate in an objective and credible analysis of stationary fuel cell systems to benchmark the current state of the technology and support industry growth.
Positive periodic solutions for a neutral Lotka-Volterra system with state dependent delays
NASA Astrophysics Data System (ADS)
Li, Yongkun; Zhao, Lili
2009-04-01
By using a fixed point theorem of strict-set-contraction, some new criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka-Volterra system with state dependent delays
Non-periodic discrete Schrödinger equations: ground state solutions
NASA Astrophysics Data System (ADS)
Chen, Guanwei; Schechter, Martin
2016-06-01
In this paper, we study a class of non-periodic discrete Schrödinger equations with superlinear non-linearities at infinity. Under conditions weaker than those previously assumed, we obtain the existence of ground state solutions, i.e., non-trivial solutions with least possible energy. In addition, an example is given to illustrate our results.
Ceramic stationary gas turbine
Roode, M. van
1995-10-01
The performance of current industrial gas turbines is limited by the temperature and strength capabilities of the metallic structural materials in the engine hot section. Because of their superior high-temperature strength and durability, ceramics can be used as structural materials for hot section components (blades, nozzles, combustor liners) in innovative designs at increased turbine firing temperatures. The benefits include the ability to increase the turbine inlet temperature (TIT) to about 1200{degrees}C ({approx}2200{degrees}F) or more with uncooled ceramics. It has been projected that fully optimized stationary gas turbines would have a {approx}20 percent gain in thermal efficiency and {approx}40 percent gain in output power in simple cycle compared to all metal-engines with air-cooled components. Annual fuel savings in cogeneration in the U.S. would be on the order of 0.2 Quad by 2010. Emissions reductions to under 10 ppmv NO{sub x} are also forecast. This paper describes the progress on a three-phase, 6-year program sponsored by the U.S. Department of Energy, Office of Industrial Technologies, to achieve significant performance improvements and emissions reductions in stationary gas turbines by replacing metallic hot section components with ceramic parts. Progress is being reported for the period September 1, 1994, through September 30, 1995.
Ceramic stationary gas turbine
Roode, M. van
1995-12-31
The performance of current industrial gas turbines is limited by the temperature and strength capabilities of the metallic structural materials in the engine hot section. Because of their superior high-temperature strength and durability, ceramics can be used as structural materials for hot section components (blades, nozzles, combustor liners) in innovative designs at increased turbine firing temperatures. The benefits include the ability to increase the turbine inlet temperature (TIT) to about 1200{degrees}C ({approx}2200{degrees}F) or more with uncooled ceramics. It has been projected that fully optimized stationary gas turbines would have a {approx}20 percent gain in thermal efficiency and {approx}40 percent gain in output power in simple cycle compared to all metal-engines with air-cooled components. Annual fuel savings in cogeneration in the U.S. would be on the order of 0.2 Quad by 2010. Emissions reductions to under 10 ppmv NO{sub x} are also forecast. This paper describes the progress on a three-phase, 6-year program sponsored by the U.S. Department of Energy, Office of Industrial Technologies, to achieve significant performance improvements and emissions reductions in stationary gas turbines by replacing metallic hot section components with ceramic parts. Progress is being reported for the period September 1, 1994, through September 30, 1995.
State-constrained booster trajectory solutions via finite elements and shooting
NASA Technical Reports Server (NTRS)
Bless, Robert R.; Hodges, Dewey H.; Seywald, Hans
1993-01-01
This paper presents an extension of a FEM formulation based on variational principles. A general formulation for handling internal boundary conditions and discontinuities in the state equations is presented, and the general formulation is modified for optimal control problems subject to state-variable inequality constraints. Solutions which only touch the state constraint and solutions which have a boundary arc of finite length are considered. Suitable shape and test functions are chosen for a FEM discretization. All element quadrature (equivalent to one-point Gaussian quadrature over each element) may be done in closed form. The final form of the algebraic equations is then derived. A simple state-constrained problem is solved. Then, for a practical application of the use of the FEM formulation, a launch vehicle subject to a dynamic pressure constraint (a first-order state inequality constraint) is solved. The results presented for the launch-vehicle trajectory have some interesting features, including a touch-point solution.
PROCESS OF SECURING PLUTONIUM IN NITRIC ACID SOLUTIONS IN ITS TRIVALENT OXIDATION STATE
Thomas, J.R.
1958-08-26
>Various processes for the recovery of plutonium require that the plutonium be obtalned and maintained in the reduced or trivalent state in solution. Ferrous ions are commonly used as the reducing agent for this purpose, but it is difficult to maintain the plutonium in a reduced state in nitric acid solutions due to the oxidizing effects of the acid. It has been found that the addition of a stabilizing or holding reductant to such solution prevents reoxidation of the plutonium. Sulfamate ions have been found to be ideally suitable as such a stabilizer even in the presence of nitric acid.
Solution of steady-state one-dimensional conservation laws by mathematical programming
NASA Technical Reports Server (NTRS)
Lavery, J. E.
1989-01-01
Solution techniques for a class of steady-state scalar conservation laws are developed analytically. Discretization by finite-volume formulas is employed to obtain an overdetermined system of algebraic equations, which are then perturbed nonsingularly (with perturbation coefficient = epsilon) and solved using the l(1) mathematical-programming algorithm of Seneta and Steiger (1984); this approach limits the matrix bandwidth to two, so that an explicit solution can be found efficiently. It is shown that, for small values of epsilon, the l(1) solutions exhibit sharp correctly located shocks and are nonoscillatory O(epsilon) approximations of the physically relevant solutions.
Integrating matrix solution of the hybrid state vector equations for beam vibration
NASA Technical Reports Server (NTRS)
Lehman, L. L.
1982-01-01
A simple, versatile, and efficient computational technique has been developed for dynamic analysis of linear elastic beam and rod type of structures. Moreover, the method provides a rather general solution approach for two-point boundary value problems that are described by a single independent spatial variable. For structural problems, the method is implemented by a mixed state vector formulation of the differential equations, combined with an integrating matrix solution procedure. Highly accurate solutions are easily achieved with this approach. Example solutions are given for beam vibration problems including discontinuous stiffness and mass parameters, elastic restraint boundary conditions, concentrated inertia loading, and rigid body modes
Analytical solution of the heat equation in a longitudinally pumped cubic solid-state laser
Sabaeian, Mohammad; Nadgaran, Hamid; Mousave, Laleh
2008-05-01
Knowledge about the temperature distribution inside solid-state laser crystals is essential for calculation of thermal phase shift, thermal lensing, thermally induced birefringence, and heat-induced crystal bending. Solutions for the temperature distribution for the case of steady-state heat loading have appeared in the literature only for simple cylindrical crystal shapes and are usually based on numerical techniques. For the first time, to our knowledge, a full analytical solution of the heat equation for an anisotropic cubic cross-section solid-state crystal is presented. The crystal is assumed to be longitudinally pumped by a Gaussian pump profile. The pump power attenuation along the crystal and the real cooling mechanisms, such as convection, are considered in detail. A comparison between our analytical solutions and its numerical counterparts shows excellent agreement when just a few terms are employed in the series solutions.
Nuclear magnetic resonance investigation of the state of water in protein solution.
Uemitsu, N; Oashi, H; Matsumiya, H
1975-07-01
The line width of the NMR signal of water protons in solutions of native actomyosin and actomyosin denatured by heat, acetone or urea was measured over the temperature range from -10 degrees to below the freezing point. The line widths of the water band which increased exponentially with decreasing temperature were compared with each other and also with those of the corresponding control solution without actomyosin. The line broadening observed for native actomyosin solution on lowering the temperature was significantly smaller than that for heat-denatured actomyosin solution. This difference implies that this signal is sensitive to conformational perturbations of the protein. In addition, the temperature dependence of the line width for heat-, acetone-, or urea-denatured actomyosin solution was similar to that for the corresponding control solution. These phenomena can be interpreted in terms of the state of water associated with the hydrophobic and hydrophilic residues. Similar NMR studies of actomyosin solution containing dimethyl sulfoxide (DMSO) or dimethylformamide (DMF) showed that DMSO and DMF prevent the formation of ice crystals until about -70 degrees, suggesting that the cryoprotective effects of DMSO and DMF are due to the change in the state of water described above. These differences in temperature dependence between the sample and control solutions are well-correlated with the viscosity of the solution. This correlation is useful for elucidation of the mechanism of the protein denaturation. PMID:1194253
NASA Astrophysics Data System (ADS)
Dhar, Abhishek; Sriram Shastry, B.
2000-09-01
We present a calculation of the lowest excited states of the Heisenberg ferromagnet in 1D for any wave vector. These turn out to be string solutions of Bethe's equations with a macroscopic number of particles in them. They are identified as generalized quantum Bloch wall states, and a simple physical picture is provided for the same.
Stationary engineering handbook
Petrocelly, K.L.
1989-01-01
Years ago, the only qualifications you needed to become to become an operating engineer were the ability to shovel large chunks of coal through small furnace doors and the fortitude to sweat profusely for hours without fainting. As a consequence of technological evolution, the engineer's coal shovels have been replaced with computers and now perspiration is more the result of job stress than exposure to high temperatures. The domain of the operator has been extended far beyond the smoke-filled caverns that once encased him, out into the physical plant, and his responsibilities have been expanded accordingly. Unlike his less sophisticated predecessor, today's technician must be well versed in all aspects of the operation. The field of power plant operations has become a full-fledged profession and its principals are called Stationary Engineers. This book addresses the areas of responsibility and the education and skills needed for successful operation of building services equipment.
Thermocapillary Convection Due to a Stationary Bubble - A Paradox
NASA Technical Reports Server (NTRS)
Balasubramaniam, R.; Subramanian, R. S.
2003-01-01
We analyze the velocity and temperature fields at steady state due to thermocapillary convection around a gas bubble that is stationary in a liquid. A linear temperature field is imposed in the undisturbed liquid. Our interest is in investigating the effect of convective transport of momentum and energy on the velocity and temperature fields. We assume the pertinent physical properties to be constant, and that buoyant convection is negligible. Suitably defined Reynolds and Marangoni numbers are assumed to be small compared with unity. When both the Reynolds and Marangoni numbers are set equal to zero, a solution can be found. In this solution, far from the bubble, the velocity field decays as the inverse of the distance from the bubble, and the disturbance temperature field decays as the inverse of the square of this distance. We now attempt to obtain a solution when the Reynolds number is zero, but the Marangoni number is small, but non-zero, by a perturbation expansion in the Marangoni number. When the temperature field is expanded in a regular perturbation series in the Marangoni number, we show that the problem for the first correction field is ill-posed. The governing equation for this perturbation field contains an inhomogeneity, and the corresponding particular solution neither decays far from the bubble, nor can be canceled by a homogeneous solution. Additional information is included in the original extended abstract.
Stationary second-degree iterative methods and recurrences
Kincaid, D.R.; Young, D.M.
1991-02-01
The basic theory of stationary second-degree iterative methods is presented from the point of view of recurrences. Recurrences are encountered in the development of expressions for the spectral radii and for various norms associated with linear stationary iterative methods. We show that many of these recurrences are special cases of a single general recurrence and that its closed-form solution leads to these expressions. Citations are given showing where the expressions occur in the theory of iterative methods.
Stability of erythrocyte suspensions layered on stationary and flowing liquids
NASA Technical Reports Server (NTRS)
Omenyi, S. N.; Rhodes, P. H.; Snyder, R. S.
1982-01-01
The apparent stability of erythrocyte suspensions layered on stationary and flowing Ficoll solutions was studied considering the effects of particle concentration, type and size, and the different flow rates of the particle suspensions and chamber liquid. The data from the flowing system were empirically fitted and, when extrapolated to zero chamber liquid flow rate, gave values comparable to the data from the stationary system, thus confirming the validity of the data and our approach to obtain that data.
Stationary Engineering Laboratory Manual--2.
ERIC Educational Resources Information Center
Steingress, Frederick M.; Frost, Harold J.
The Stationary Engineering Laboratory Manual 2 was designed for vocational/technical high school students who have received instruction in the basics of stationary engineering. It was developed for students who will be operating a live plant and who will be responsible for supplying steam for heating, cooking, and baking. Each lesson in the manual…
Stationary Engineering. Science Manual--2.
ERIC Educational Resources Information Center
Frost, Harold J.; Steingress, Frederick M.
This second-year student manual contains 140 brief related science lessons applying science and math to trade activities in the field of stationary engineering. The lessons are organized into 16 units: (1) Introduction to Stationary Engineering, (2) Engineering Fundamentals, (3) Steam Boilers, (4) Boiler Fittings, (5) Boilerroom System, (6)…
Iterative solutions to the steady-state density matrix for optomechanical systems.
Nation, P D; Johansson, J R; Blencowe, M P; Rimberg, A J
2015-01-01
We present a sparse matrix permutation from graph theory that gives stable incomplete lower-upper preconditioners necessary for iterative solutions to the steady-state density matrix for quantum optomechanical systems. This reordering is efficient, adding little overhead to the computation, and results in a marked reduction in both memory and runtime requirements compared to other solution methods, with performance gains increasing with system size. Either of these benchmarks can be tuned via the preconditioner accuracy and solution tolerance. This reordering optimizes the condition number of the approximate inverse and is the only method found to be stable at large Hilbert space dimensions. This allows for steady-state solutions to otherwise intractable quantum optomechanical systems. PMID:25679739
Stationary Waves of the Ice Age Climate.
NASA Astrophysics Data System (ADS)
Cook, Kerry H.; Held, Isaac M.
1988-08-01
A linearized, steady state, primitive equation model is used to simulate the climatological zonal asymmetries (stationary eddies) in the wind and temperature fields of the 18 000 YBP climate during winter. We compare these results with the eddies simulated in the ice age experiments of Broccoli and Manabe, who used CLIMAP boundary conditions and reduced atmospheric CO2 in an atmospheric general circulation model (GCM) coupled with a static mixed layer ocean model. The agreement between the models is good, indicating that the linear model can be used to evaluate the relative influences of orography, diabatic heating, and transient eddy heat and momentum transports in generating stationary waves. We find that orographic forcing dominates in the ice age climate. The mechanical influence of the continental ice sheets on the atmosphere is responsible for most of the changes between the present day and ice age stationary eddies. This concept of the ice age climate is complicated by the sensitivity of the stationary eddies to the large increase in the magnitude of the zonal mean meridional temperature gradient simulated in the ice age GCM.
Trumpet solution from spherical gravitational collapse with puncture gauges
Thierfelder, Marcus; Bernuzzi, Sebastiano; Hilditch, David; Bruegmann, Bernd; Rezzolla, Luciano
2011-03-15
We investigate the stationary end state obtained by evolving a collapsing spherical star with the gauges routinely adopted to study puncture black holes. We compare the end state of the collapse with the trumpet solution found in the evolution of a single wormhole slice and show that the two solutions closely agree. We demonstrate that the agreement is caused by the use of the Gamma-driver shift condition, which allows the matter to fall inwards into a region of spacetime that is not resolved by the numerical grid, and which simultaneously finds the stationary coordinates of the trumpet outside the matter.
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
Numerical solution of a coupled pair of elliptic equations from solid state electronics
NASA Technical Reports Server (NTRS)
Phillips, T. N.
1983-01-01
Iterative methods are considered for the solution of a coupled pair of second order elliptic partial differential equations which arise in the field of solid state electronics. A finite difference scheme is used which retains the conservative form of the differential equations. Numerical solutions are obtained in two ways, by multigrid and dynamic alternating direction implicit methods. Numerical results are presented which show the multigrid method to be an efficient way of solving this problem.
Approximate semi-analytical solutions for the steady-state expansion of a contactor plasma
NASA Astrophysics Data System (ADS)
Camporeale, E.; Hogan, E. A.; MacDonald, E. A.
2015-04-01
We study the steady-state expansion of a collisionless, electrostatic, quasi-neutral plasma plume into vacuum, with a fluid model. We analyze approximate semi-analytical solutions, that can be used in lieu of much more expensive numerical solutions. In particular, we focus on the earlier studies presented in Parks and Katz (1979 American Institute of Aeronautics, Astronautics Conf. vol 1), Korsun and Tverdokhlebova (1997 33rd Joint Prop. Conf. (Seattle, WA) AIAA-97-3065), and Ashkenazy and Fruchtman (2001 27th Int. Electric Propulsion Conf. (Pasadena, CA)). By calculating the error with respect to the numerical solution, we can judge the range of validity for each solution. Moreover, we introduce a generalization of earlier models that has a wider range of applicability, in terms of plasma injection profiles. We conclude by showing a straightforward way to extend the discussed solutions to the case of a plasma plume injected with non-null azimuthal velocity.
Similarity Solutions of the Compressible Flow Equations for a General Equation of State
NASA Astrophysics Data System (ADS)
Boyd, Zachary; Ramsey, Scott; Baty, Roy
2015-11-01
The Euler compressible flow equations admit discontinuous (e.g. shock) solutions regardless of the equation of state (EOS) used to close them. In addition, certain classes of initial conditions and EOS admit special flows known as similarity solutions, including some containing shocks. These are useful (1) as test problems for hydrocodes, (2) as intermediate asymptotic estimates for non-symmetric problems, and (3) in forecasting experimental results. To date, the vast majority of work pertaining to similarity solutions of the Euler equations has been accomplished in the context of the ideal gas EOS; the case where the material is arbitrary is less well-understood. In this work, we classify using Lie-group analysis those materials which admit similarity solutions. We also indicate how such solutions may be found for a variety of materials of interest, including those characterized by particular forms of the Gruneisen EOS. Graduate Student Department of Mathematics, UCLA.
f-state luminescence of lanthanide and actinide ions in solution
Beitz, J.V.
1993-09-01
Detailed studies of the luminescence of aquated Am{sup 3+} are presented in the context of prior lanthanide and actinide ion work. The luminescing state of aquated Am{sup 3+} is confirmed to be {sup 5}D{sub l} based on observed emission and excitation spectra. The luminescence lifetime of Am{sup 3+} in H{sub 2}O solution is (22 {plus_minus} 3) ns and (155 {plus_minus} 4) ns in D{sub 2}O solution at 295 K. Judd-Ofelt transition intensity theory qualitatively describes the observed Am{sup 3+} relative integrated fluorescence intensities. Recent luminescence studies on complexed trivalent f-element ions in solution are reviewed as to the similarities and differences between lanthanide ion 4f state and actinide ion 5f state properties.
Zaidel, Jacob
2013-01-01
Known analytical solutions of groundwater flow equations are routinely used for verification of computer codes. However, these analytical solutions (e.g., the Dupuit solution for the steady-state unconfined unidirectional flow in a uniform aquifer with a flat bottom) represent smooth and continuous water table configurations, simulating which does not pose any significant problems for the numerical groundwater flow models, like MODFLOW. One of the most challenging numerical cases for MODFLOW arises from drying-rewetting problems often associated with abrupt changes in the elevations of impervious base of a thin unconfined aquifer. Numerical solutions of groundwater flow equations cannot be rigorously verified for such cases due to the lack of corresponding exact analytical solutions. Analytical solutions of the steady-state Boussinesq equation, associated with the discontinuous water table configurations over a stairway impervious base, are presented in this article. Conditions resulting in such configurations are analyzed and discussed. These solutions appear to be well suited for testing and verification of computer codes. Numerical solutions, obtained by the latest versions of MODFLOW (MODFLOW-2005 and MODFLOW-NWT), are compared with the presented discontinuous analytical solutions. It is shown that standard MODFLOW-2005 code (as well as MODFLOW-2000 and older versions) has significant convergence problems simulating such cases. The problems manifest themselves either in a total convergence failure or erroneous results. Alternatively, MODFLOW-NWT, providing a good match to the presented discontinuous analytical solutions, appears to be a more reliable and appropriate code for simulating abrupt changes in water table elevations. PMID:23387826
Analytical steady-state solutions for water-limited cropping systems using saline irrigation water
NASA Astrophysics Data System (ADS)
Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.
2014-12-01
Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess advantages over available alternatives, including: (i) the solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.
Stationary spiral flow in polytropic stellar models
Pekeris, C.L.
1980-06-01
It is shown that, in addition to the static Emden solution, a self-gravitating polytropic gas has a dynamic option in which there is stationary flow along spiral trajectories wound around the surfaces of concentric tori. The motion is obtained as a solution of a partial differential equation which is satisfied by the meridional stream function, coupled with Poisson's equation and a Bernoulli-type equation for the pressure (density). The pressure is affected by the whole of the Bernoulli term rather than by the centrifugal part only, which acts for a rotating model, and it may be reduced down to zero at the center. The spiral type of flow is illustrated for an incompressible fluid (n = 0), for which an exact solution is obtained. The features of the dynamic constant-density model are discussed as a basis for future comparison with the solution for compressible models.
Complex plasma in g ×B configurations: Stability switching and stationary structure
NASA Astrophysics Data System (ADS)
Salahshoor, M.; Niknam, A. R.
2015-08-01
In a low-pressure magneto-gravitated complex plasma, the stability state of dust gravitational drift wave is switched at a critical wavenumber and the propagating dust magneto-gravitational drift wave is transformed into an aperiodic stationary structure at a cut-off wavenumber. In this paper, two analytical formulas have been derived for the critical wavenumber of stability switching and the cut-off wavenumber of stationary structure. The critical wavenumber is equal to the ratio of ion plasma frequency to ion streaming velocity and the cut-off wavenumber is proportional to the ratio of dust plasma frequency to dust g ×B drift velocity. These scaling formulas are in excellent agreement with exact numerical solutions of dispersion relations. These scenarios are expected to be observed in fully magnetized dusty plasma experiments as the next frontier for complex plasma research.
Steady-state fluctuations of a genetic feedback loop: An exact solution
NASA Astrophysics Data System (ADS)
Grima, R.; Schmidt, D. R.; Newman, T. J.
2012-07-01
Genetic feedback loops in cells break detailed balance and involve bimolecular reactions; hence, exact solutions revealing the nature of the stochastic fluctuations in these loops are lacking. We here consider the master equation for a gene regulatory feedback loop: a gene produces protein which then binds to the promoter of the same gene and regulates its expression. The protein degrades in its free and bound forms. This network breaks detailed balance and involves a single bimolecular reaction step. We provide an exact solution of the steady-state master equation for arbitrary values of the parameters, and present simplified solutions for a number of special cases. The full parametric dependence of the analytical non-equilibrium steady-state probability distribution is verified by direct numerical solution of the master equations. For the case where the degradation rate of bound and free protein is the same, our solution is at variance with a previous claim of an exact solution [J. E. M. Hornos, D. Schultz, G. C. P. Innocentini, J. Wang, A. M. Walczak, J. N. Onuchic, and P. G. Wolynes, Phys. Rev. E 72, 051907 (2005), 10.1103/PhysRevE.72.051907, and subsequent studies]. We show explicitly that this is due to an unphysical formulation of the underlying master equation in those studies.
Coherent states and nonlinear dynamics of the three state quasi-spin model with soliton solutions
NASA Astrophysics Data System (ADS)
Agüero, M.; Alvarado, R.; Frias, M.
1998-11-01
In this paper the generalized coherent states defined as points of the coset space {SU(2)}/{U(1)} are used as trial wave functions in order to study the quasi-spin model of the nonlinear ϕ6-theory. In the simple version of the quasi-classical theory deduced from this method a complete integrable system is obtained. In a general context, the ground state and linear spectrum of the nonlinear lattice equation were evaluated. Finally, by analyzing the effective potential, the first and second order phase transitions are shown to exist.
NASA Astrophysics Data System (ADS)
Takada, K.; Tomioka, A.
2012-04-01
Liquid-phase laser processing, where the laser-irradiated target material is immersed in water for cooling, has been reported as a promising processing technique for thermally fragile organic materials. Although nanometer-sized particles have been reported to be obtained with the liquid-phase laser processing, the physical property did not change because quantum-mechanical size effect does not exhibit itself in the zero-radius Frenkel excitons. In the present study, we step further to use solution droplets as a target material, where organic molecules are molecularly dispersed in organic solvent and, therefore, expected to easily alter the conformation and the energy state upon laser irradiation. Small volume organic solvent is quickly evaporated upon laser irradiation, letting the bare organic molecule placed in water and rapidly cooled. To prevent the chemical decomposition of the target π-conjugated molecule, the specimen was resonantly irradiated by a ns-pulse green laser, not by a conventional UV laser. When the solid state spin-coat film made from MEH-PPV chloroform solution was used as a irradiation target immersed in water, resulting MEH-PPV particles showed similar photoluminescence (PL) like the PL of the spin-coat film and PL of the chloroform solution, including the 0→1, 0→2 vibrational transitions: this indicates that the energy levels were not modified from the spin-coat film. In comparison, when tiny droplets of MEH-PPV chloroform solution (orange color) were suspended in water, laser irradiation gave rise to yellow MEH-PPV particles which showed 550 nm and 530 nm PL (type B), blue-shifted from the spin-coat film PL 580 nm (type A), suggesting a successful phase transition of MEH-PPV polymer to type B. Further solution-phase laser processing left the type B state unchanged. The irreversible phase transition from type A to type B suggests that the type B ground state has lower energy than type A, which is consistent with the blue-shifted PL of
Iron salts in solid state and in frozen solutions as dosimeters for low irradiation temperatures.
Martínez, T; Lartigue, J; Ramos-Bernal, S; Ramos, A; Mosqueira, G F; Negrón-Mendoza, A
2005-01-01
The aim of this work is to study the irradiation of iron salts in solid state (heptahydrated ferrous sulfate) and in frozen acid solutions. The study is focused on finding their possible use as dosimeters for low temperature irradiations and high doses. The analysis of the samples was made by UV-visible and Mössbauer spectroscopies. The output signal was linear from 0 to 10 MGy for the solid samples, and 0-600 Gy for the frozen solutions. The obtained data is reproducible and easy to handle. For these reasons, heptahydrate iron sulfate is a suitable dosimeter for low temperature and high irradiation doses, in solid state, and in frozen solution. PMID:15985374
State-space solutions to standard H2 and H(infinity) control problems
NASA Technical Reports Server (NTRS)
Doyle, John C.; Glover, Keith; Khargonekar, Pramod P.; Francis, Bruce A.
1989-01-01
Simple state-space formulas are derived for all controllers solving the standard H(infinity) problem of finding, for a given number gamma greater than 0, all controllers such that the H(infinity) norm of the closed-loop transfer function is (strictly) less than gamma. It is known that a controller exists if and only if the unique stabilizing solutions to two algebraic Riccati equations are positive definite and the spectral radius of their product is less than gamma squared. Under these conditions, a parameterization of all controllers solving the problem is given as a linear fractional transformation (LFT) on a contractive stable free parameter. The state dimension of the coefficient matrix for the LFT, constructed using the two Riccati solutions, equals that of the plant and has a separation structure reminiscent of classical LQG (i.e., H2) theory. A standard H2 solution is developed in parallel.
Jehle, Stefan; van Rossum, Barth; Stout, Joseph R.; Noguchi, Satoshi M.; Falber, Katja; Rehbein, Kristina; Oschkinat, Hartmut; Klevit, Rachel E.; Rajagopal, Ponni
2008-11-14
Atomic-level structural information on αB-Crystallin (αB), a prominent member of the small heat-shock protein family, has been a challenge to obtain due its polydisperse oligomeric nature. We show that magic-angle spinning solid-state NMR can be used to obtain high-resolution information on an ~580-kDa human αB assembled from 175-residue 20-kDa subunits. An ~100-residue α-crystallin domain is common to all small heat-shock proteins, and solution-state NMR was performed on two different α- crystallin domain constructs isolated from αB. In vitro, the chaperone-like activities of full-length αB and the isolated α-crystallin domain are identical. Chemical shifts of the backbone and C^{β }resonances have been obtained for residues 64–162 (α-crystallin domain plus part of the C-terminus) in αB and the isolated α-crystallin domain by solid-state and solution-state NMR, respectively. Both sets of data strongly predict six β-strands in the α-crystallin domain. A majority of residues in the α-crystallin domain have similar chemical shifts in both solid-state and solution-state, indicating similar structures for the domain in its isolated and oligomeric forms. Sites of intersubunit interaction are identified from chemical shift differences that cluster to specific regions of the α-crystallin domain. Multiple signals are observed for the resonances of M68 in the oligomer, identifying the region containing this residue as existing in heterogeneous environments within αB. Evidence for a novel dimerization motif in the human α-crystallin domain is obtained by a comparison of (i) solid-state and solution-state chemical shift data and (ii) ^{1}H–^{15}N heteronuclear single quantum coherence spectra as a function of pH. The isolated α-crystallin domain undergoes a dimer–monomer transition over the pH range 7.5–6.8. This steep pHdependent switch may be important for αB to function optimally (e.g., to preserve the filament integrity
Investigation of the oxidation states of Pu isotopes in a hydrochloric acid solution.
Lee, M H; Kim, J Y; Kim, W H; Jung, E C; Jee, K Y
2008-12-01
The characteristics of the oxidation states of Pu in a hydrochloric acid solution were investigated and the results were applied to a separating of Pu isotopes from IAEA reference soils. The oxidation states of Pu(III) and Pu(IV) were prepared by adding hydroxylamine hydrochloride and sodium nitrite to a Pu stock solution, respectively. Also, the oxidation state of Pu(VI) was adjusted with concentrated HNO(3) and HClO(4). The stability of the various oxidation states of plutonium in a HCl solution with elapsed time after preparation were found to be in the following order: Pu(III) approximately Pu(VI)>Pu(IV)>Pu(V). The chemical recoveries of Pu(IV) in a 9M HCl solution with an anion exchange resin were similar to those of Pu(VI). This method for the determination of Pu isotopes with an anion exchange resin in a 9M HCl medium was applied to IAEA reference soils where the activity concentrations of (239,240)Pu and (238)Pu in IAEA-375 and IAEA-326 were consistent with the reference values reported by the IAEA. PMID:18674920
USING HIGH-RESOLUTION SOLUTION-STATE NMR SPECTROSCOPY TO INVESTIGATE PMDI REACTIONS WITH WOOD
Technology Transfer Automated Retrieval System (TEKTRAN)
Solution-state NMR spectroscopy provides a powerful tool for understanding the formation of chemical bonds between wood components and adhesives. Finely ground cell wall (CW) material fully dissolves in a solvent system containing dimethylsulfoxide (DMSO-d6) and N-methyl¬imidazole (NMI-d6), keeping ...
Existence and uniqueness of steady state solutions of a nonlocal diffusive logistic equation
NASA Astrophysics Data System (ADS)
Sun, Linan; Shi, Junping; Wang, Yuwen
2013-08-01
In this paper, we consider a dynamical model of population biology which is of the classical Fisher type, but the competition interaction between individuals is nonlocal. The existence, uniqueness, and stability of the steady state solution of the nonlocal problem on a bounded interval with homogeneous Dirichlet boundary conditions are studied.
NASA Astrophysics Data System (ADS)
Gorbatenko, M. V.; Neznamov, V. P.; Popov, E. Yu; Safronov, I. I.
2016-02-01
The paper explores quantum mechanics of half-spin particle motion in the field of Reissner-Nordström (RN) naked singularity. It is shown that for any quantum mechanical Dirac particle, irrespective of availability and sign of its electrical charge, the RN naked singularity is separated by an infinitely high positive potential barrier. With like charges of a particle and the source of the RN naked singularity, near the origin there exists the second completely impenetrable potential barrier. It has been proved that in the field of the RN naked singularity, bound states of half-spin particles can exist. The conditions for appearance of such states were revealed and computations were performed to find energy eigenvalues and eigenfunctions.
Stationary Plasma Thruster Plume Emissions
NASA Technical Reports Server (NTRS)
Manzella, David H.
1994-01-01
The emission spectrum from a xenon plasma produced by a Stationary Plasma Thruster provided by the Ballistic Missile Defense Organization (BMDO) was measured. Approximately 270 individual Xe I, Xe II, and XE III transitions were identified. A total of 250 mW of radiated optical emission was estimated from measurements taken at the thruster exit plane. There was no evidence of erosion products in the emission signature. Ingestion and ionization of background gas at elevated background pressure was detected. The distribution of excited states could be described by temperatures ranging from fractions of 1 eV to 4 eV with a high degree of uncertainty due to the nonequilibrium nature of this plasma. The plasma was over 95 percent ionized at the thruster exit plane. Between 10 and 20 percent of the ions were doubly charged. Two modes of operation were identified. The intensity of plasma emission increased by a factor of two during operation in an oscillatory mode. The transfer between the two modes of operation was likely related to unidentified phenomena occurring on a time scale of minutes.
A fluorescent chemosensor for Zn(II). Exciplex formation in solution and the solid state.
Bencini, Andrea; Berni, Emanuela; Bianchi, Antonio; Fornasari, Patrizia; Giorgi, Claudia; Lima, Joao C; Lodeiro, Carlos; Melo, Maria J; de Melo, J Seixas; Parola, Antonio Jorge; Pina, Fernando; Pina, Joao; Valtancoli, Barbara
2004-07-21
The macrocyclic phenanthrolinophane 2,9-[2,5,8-triaza-5-(N-anthracene-9-methylamino)ethyl]-[9]-1,10-phenanthrolinophane (L) bearing a pendant arm containing a coordinating amine and an anthracene group forms stable complexes with Zn(II), Cd(II) and Hg(II) in solution. Stability constants of these complexes were determined in 0.10 mol dm(-3) NMe(4)Cl H(2)O-MeCN (1:1, v/v) solution at 298.1 +/- 0.1 K by means of potentiometric (pH metric) titration. The fluorescence emission properties of these complexes were studied in this solvent. For the Zn(II) complex, steady-state and time-resolved fluorescence studies were performed in ethanol solution and in the solid state. In solution, intramolecular pi-stacking interaction between phenanthroline and anthracene in the ground state and exciplex emission in the excited state were observed. From the temperature dependence of the photostationary ratio (I(Exc)/I(M)), the activation energy for the exciplex formation (E(a)) and the binding energy of the exciplex (-DeltaH) were determined. The crystal structure of the [ZnLBr](ClO(4)).H(2)O compound was resolved, showing that in the solid state both intra- and inter-molecular pi-stacking interactions are present. Such interactions were also evidenced by UV-vis absorption and emission spectra in the solid state. The absorption spectrum of a thin film of the solid complex is red-shifted compared with the solution spectra, whereas its emission spectrum reveals the unique featureless exciplex band, blue shifted compared with the solution. In conjunction with X-ray data the solid-state data was interpreted as being due to a new exciplex where no pi-stacking (full overlap of the pi-electron cloud of the two chromophores - anthracene and phenanthroline) is observed. L is a fluorescent chemosensor able to signal Zn(II) in presence of Cd(II) and Hg(II), since the last two metal ions do not give rise either to the formation of pi-stacking complexes or to exciplex emission in solution. PMID
Higher order stationary subspace analysis
NASA Astrophysics Data System (ADS)
Panknin, Danny; von Bünau, Paul; Kawanabe, Motoaki; Meinecke, Frank C.; Müller, Klaus-Robert
2016-03-01
Non-stationarity in data is an ubiquitous problem in signal processing. The recent stationary subspace analysis procedure (SSA) has enabled to decompose such data into a stationary subspace and a non-stationary part respectively. Algorithmically only weak non- stationarities could be tackled by SSA. The present paper takes the conceptual step generalizing from the use of first and second moments as in SSA to higher order moments, thus defining the proposed higher order stationary subspace analysis procedure (HOSSA). The paper derives the novel procedure and shows simulations. An obvious trade-off between the necessity of estimating higher moments and the accuracy and robustness with which they can be estimated is observed. In an ideal setting of plenty of data where higher moment information is dominating our novel approach can win against standard SSA. However, with limited data, even though higher moments actually dominate the underlying data, still SSA may arrive on par.
The stationary source compliance audit program
Autry, L.P.
1999-07-01
On November 15, 1990, the Clean Air Act (CAA) was amended and a list of 189 compounds that are considered to be Hazardous Air Pollutants (HAPs) was included. These pollutants are to be regulated through the development of Toxics Methods, which include Maximum Achievable Control Technology (MACT) Standards, and New Source Performance Standards (NSPS). In support of these Federal regulations, audit materials are developed, validated, and provided to State and local agencies to ensure high quality source emissions compliance data. These performance evaluation samples have traditionally been requested from the Stationary Source Compliance Test Coordinator of the Environmental Protection Agencies (EPA's) National Exposure Research Laboratory (NERL) by the regulatory agency for who the compliance test is being conducted. As of January 1, 1998, the Stationary Source Compliance Audit Program (SSCAP) was taken over by the EPA's Emission Measurement Center (EMC) and many changes instituted. These modifications to the program provide a more effective and efficient way to implement the performance evaluations.
Generalized stationary phase approximations for mountain waves
NASA Astrophysics Data System (ADS)
Knight, H.; Broutman, D.; Eckermann, S. D.
2016-04-01
Large altitude asymptotic approximations are derived for vertical displacements due to mountain waves generated by hydrostatic wind flow over arbitrary topography. This leads to new asymptotic analytic expressions for wave-induced vertical displacement for mountains with an elliptical Gaussian shape and with the major axis oriented at any angle relative to the background wind. The motivation is to understand local maxima in vertical displacement amplitude at a given height for elliptical mountains aligned at oblique angles to the wind direction, as identified in Eckermann et al. ["Effects of horizontal geometrical spreading on the parameterization of orographic gravity-wave drag. Part 1: Numerical transform solutions," J. Atmos. Sci. 72, 2330-2347 (2015)]. The standard stationary phase method reproduces one type of local amplitude maximum that migrates downwind with increasing altitude. Another type of local amplitude maximum stays close to the vertical axis over the center of the mountain, and a new generalized stationary phase method is developed to describe this other type of local amplitude maximum and the horizontal variation of wave-induced vertical displacement near the vertical axis of the mountain in the large altitude limit. The new generalized stationary phase method describes the asymptotic behavior of integrals where the asymptotic parameter is raised to two different powers (1/2 and 1) rather than just one power as in the standard stationary phase method. The vertical displacement formulas are initially derived assuming a uniform background wind but are extended to accommodate both vertical shear with a fixed wind direction and vertical variations in the buoyancy frequency.
Combining solid-state and solution-state 31P NMR to study in vivo phosphorus metabolism.
Cholli, A L; Yamane, T; Jelinski, L W
1985-01-01
Otherwise unavailable information concerning the distribution of phosphorylated compounds in biological systems is obtained by a combined solid-state/solution-state NMR approach, illustrated here for oocytes from Rana pipiens. General methodology is developed, and further extensions are proposed. The following conclusions pertain to the specific system under examination. (i) Nucleoside phosphates can be observed by magic-angle sample spinning of the lyophilized material. (ii) The solid-state NMR technique of dipolar decoupling provides no additional resolution of the phospholipid and phosphoprotein components of the yolk. However, cellular death produces sufficient pH changes to cause the phospholipid and protein phosphate peaks to become resolvable. The concentration of nucleoside phosphates also decreases. (iii) The phospholipid and phosphoprotein components are shown by computer simulation to be present in a ratio of 40:60, respectively. (iv) The amounts of inorganic phosphate, nucleoside phosphates, and sugar phosphates are determined by solution-state NMR observation of the perchloric acid extract of the oocytes. PMID:3871524
Hao, Hua; Chang, Howard H.; Holmes, Heather A.; Mulholland, James A.; Klein, Mitch; Darrow, Lyndsey A.; Strickland, Matthew J.
2015-01-01
Background: Previous epidemiologic studies suggest associations between preterm birth and ambient air pollution. Objective: We investigated associations between 11 ambient air pollutants, estimated by combining Community Multiscale Air Quality model (CMAQ) simulations with measurements from stationary monitors, and risk of preterm birth (< 37 weeks of gestation) in the U.S. state of Georgia. Methods: Birth records for singleton births ≥ 27 weeks of gestation with complete covariate information and estimated dates of conception between 1 January 2002 and 28 February 2006 were obtained from the Office of Health Indicators for Planning, Georgia Department of Public Health (n = 511,658 births). Daily pollutant concentrations at 12-km resolution were estimated for 11 ambient air pollutants. We used logistic regression with county-level fixed effects to estimate associations between preterm birth and average pollutant concentrations during the first and second trimester. Discrete-time survival models were used to estimate third-trimester and total pregnancy associations. Effect modification was investigated by maternal education, race, census tract poverty level, and county-level urbanicity. Results: Trimester-specific and total pregnancy associations (p < 0.05) were observed for several pollutants. All the traffic-related pollutants (carbon monoxide, nitrogen dioxide, PM2.5 elemental carbon) were associated with preterm birth [e.g., odds ratios for interquartile range increases in carbon monoxide during the first, second, and third trimesters and total pregnancy were 1.005 (95% CI: 1.001, 1.009), 1.007 (95% CI: 1.002, 1.011), 1.010 (95% CI: 1.006, 1.014), and 1.011 (95% CI: 1.006, 1.017)]. Associations tended to be higher for mothers with low educational attainment and African American mothers. Conclusion: Several ambient air pollutants were associated with preterm birth; associations were observed in all exposure windows. Citation: Hao H, Chang HH, Holmes HA
On the steady-state solutions of a nonlinear photonic lattice model
NASA Astrophysics Data System (ADS)
Liu, Chungen; Ren, Qiang
2015-03-01
In this paper, we consider the steady-state solutions of the following equation related with nonlinear photonic lattice model Δ u = /P u 1 + |u|2 + |v|2 + λ u , Δ v = /Q v 1 + |u|2 + |v|2 + λ v , where u, v are real-value function defined on R/(τ1Z) × R/(τ2Z). The existence and non-existence of non-constant semi-trivial (with only one component zero) solutions are considered.
On the steady-state solutions of a nonlinear photonic lattice model
Liu, Chungen E-mail: tjftp@mail.nankai.edu.cn; Ren, Qiang E-mail: tjftp@mail.nankai.edu.cn
2015-03-15
In this paper, we consider the steady-state solutions of the following equation related with nonlinear photonic lattice model Δu=(Pu)/(1+|u|{sup 2}+|v|{sup 2}) +λu, Δv=(Qv)/(1+|u|{sup 2}+|v|{sup 2}) +λv, where u, v are real-value function defined on R/(τ{sub 1}Z) × R/(τ{sub 2}Z). The existence and non-existence of non-constant semi-trivial (with only one component zero) solutions are considered.
A multi-level solution algorithm for steady-state Markov chains
NASA Technical Reports Server (NTRS)
Horton, Graham; Leutenegger, Scott T.
1993-01-01
A new iterative algorithm, the multi-level algorithm, for the numerical solution of steady state Markov chains is presented. The method utilizes a set of recursively coarsened representations of the original system to achieve accelerated convergence. It is motivated by multigrid methods, which are widely used for fast solution of partial differential equations. Initial results of numerical experiments are reported, showing significant reductions in computation time, often an order of magnitude or more, relative to the Gauss-Seidel and optimal SOR algorithms for a variety of test problems. The multi-level method is compared and contrasted with the iterative aggregation-disaggregation algorithm of Takahashi.
Numerical solution of a coupled pair of elliptic equations from solid state electronics
NASA Technical Reports Server (NTRS)
Phillips, T. N.
1984-01-01
Iterative methods are considered for the solution of a coupled pair of second order elliptic partial differential equations which arise in the field of solid state electronics. A finite difference scheme is used which retains the conservative form of the differential equations. Numerical solutions are obtained in two ways, by multigrid and dynamic alternating direction implicit methods. Numerical results are presented which show the multigrid method to be an efficient way of solving this problem. Previously announced in STAR as N83-30109
A structural study of the intermolecular interactions of tyramine in the solid state and in solution
NASA Astrophysics Data System (ADS)
Quevedo, Rodolfo; Nuñez-Dallos, Nelson; Wurst, Klaus; Duarte-Ruiz, Álvaro
2012-12-01
The nature of the interactions between tyramine units was investigated in the solid state and in solution. Crystals of tyramine in its free base form were analyzed by Fourier transform infrared (FT-IR) spectroscopy and single-crystal X-ray diffraction (XRD). The crystal structure shows a linear molecular organization held together by "head-to-tail" intermolecular hydrogen bonds between the amino groups and the phenolic hydroxyl groups. These chains are arranged in double layers that can geometrically favor the formation of templates in solution, which may facilitate macrocyclization reactions to form azacyclophane-type compounds. Computational calculations using the PM6-DH+ method and electrospray ionization mass spectrometry (ESI-HRMS) reveal that the formation of a hydrogen-bonded tyramine dimer is favored in solution.
Cao, Youfang; Terebus, Anna; Liang, Jie
2016-04-01
The discrete chemical master equation (dCME) provides a general framework for studying stochasticity in mesoscopic reaction networks. Since its direct solution rapidly becomes intractable due to the increasing size of the state space, truncation of the state space is necessary for solving most dCMEs. It is therefore important to assess the consequences of state space truncations so errors can be quantified and minimized. Here we describe a novel method for state space truncation. By partitioning a reaction network into multiple molecular equivalence groups (MEGs), we truncate the state space by limiting the total molecular copy numbers in each MEG. We further describe a theoretical framework for analysis of the truncation error in the steady-state probability landscape using reflecting boundaries. By aggregating the state space based on the usage of a MEG and constructing an aggregated Markov process, we show that the truncation error of a MEG can be asymptotically bounded by the probability of states on the reflecting boundary of the MEG. Furthermore, truncating states of an arbitrary MEG will not undermine the estimated error of truncating any other MEGs. We then provide an overall error estimate for networks with multiple MEGs. To rapidly determine the appropriate size of an arbitrary MEG, we also introduce an a priori method to estimate the upper bound of its truncation error. This a priori estimate can be rapidly computed from reaction rates of the network, without the need of costly trial solutions of the dCME. As examples, we show results of applying our methods to the four stochastic networks of (1) the birth and death model, (2) the single gene expression model, (3) the genetic toggle switch model, and (4) the phage lambda bistable epigenetic switch model. We demonstrate how truncation errors and steady-state probability landscapes can be computed using different sizes of the MEG(s) and how the results validate our theories. Overall, the novel state space
Cao, Youfang; Terebus, Anna; Liang, Jie
2016-01-01
The discrete chemical master equation (dCME) provides a general framework for studying stochasticity in mesoscopic reaction networks. Since its direct solution rapidly becomes intractable due to the increasing size of the state space, truncation of the state space is necessary for solving most dCMEs. It is therefore important to assess the consequences of state space truncations so errors can be quantified and minimized. Here we describe a novel method for state space truncation. By partitioning a reaction network into multiple molecular equivalence groups (MEG), we truncate the state space by limiting the total molecular copy numbers in each MEG. We further describe a theoretical framework for analysis of the truncation error in the steady state probability landscape using reflecting boundaries. By aggregating the state space based on the usage of a MEG and constructing an aggregated Markov process, we show that the truncation error of a MEG can be asymptotically bounded by the probability of states on the reflecting boundary of the MEG. Furthermore, truncating states of an arbitrary MEG will not undermine the estimated error of truncating any other MEGs. We then provide an overall error estimate for networks with multiple MEGs. To rapidly determine the appropriate size of an arbitrary MEG, we also introduce an a priori method to estimate the upper bound of its truncation error. This a priori estimate can be rapidly computed from reaction rates of the network, without the need of costly trial solutions of the dCME. As examples, we show results of applying our methods to the four stochastic networks of 1) the birth and death model, 2) the single gene expression model, 3) the genetic toggle switch model, and 4) the phage lambda bistable epigenetic switch model. We demonstrate how truncation errors and steady state probability landscapes can be computed using different sizes of the MEG(s) and how the results validate out theories. Overall, the novel state space
Alarcón, Tomás
2014-05-14
In this paper, we propose two methods to carry out the quasi-steady state approximation in stochastic models of enzyme catalytic regulation, based on WKB asymptotics of the chemical master equation or of the corresponding partial differential equation for the generating function. The first of the methods we propose involves the development of multiscale generalisation of a WKB approximation of the solution of the master equation, where the separation of time scales is made explicit which allows us to apply the quasi-steady state approximation in a straightforward manner. To the lowest order, the multi-scale WKB method provides a quasi-steady state, Gaussian approximation of the probability distribution. The second method is based on the Hamilton-Jacobi representation of the stochastic process where, as predicted by large deviation theory, the solution of the partial differential equation for the corresponding characteristic function is given in terms of an effective action functional. The optimal transition paths between two states are then given by those paths that maximise the effective action. Such paths are the solutions of the Hamilton equations for the Hamiltonian associated to the effective action functional. The quasi-steady state approximation is applied to the Hamilton equations thus providing an approximation to the optimal transition paths and the transition time between two states. Using this approximation we predict that, unlike the mean-field quasi-steady approximation result, the rate of enzyme catalysis depends explicitly on the initial number of enzyme molecules. The accuracy and validity of our approximated results as well as that of our predictions regarding the behaviour of the stochastic enzyme catalytic models are verified by direct simulation of the stochastic model using Gillespie stochastic simulation algorithm. PMID:24832255
Alarcón, Tomás
2014-05-14
In this paper, we propose two methods to carry out the quasi-steady state approximation in stochastic models of enzyme catalytic regulation, based on WKB asymptotics of the chemical master equation or of the corresponding partial differential equation for the generating function. The first of the methods we propose involves the development of multiscale generalisation of a WKB approximation of the solution of the master equation, where the separation of time scales is made explicit which allows us to apply the quasi-steady state approximation in a straightforward manner. To the lowest order, the multi-scale WKB method provides a quasi-steady state, Gaussian approximation of the probability distribution. The second method is based on the Hamilton-Jacobi representation of the stochastic process where, as predicted by large deviation theory, the solution of the partial differential equation for the corresponding characteristic function is given in terms of an effective action functional. The optimal transition paths between two states are then given by those paths that maximise the effective action. Such paths are the solutions of the Hamilton equations for the Hamiltonian associated to the effective action functional. The quasi-steady state approximation is applied to the Hamilton equations thus providing an approximation to the optimal transition paths and the transition time between two states. Using this approximation we predict that, unlike the mean-field quasi-steady approximation result, the rate of enzyme catalysis depends explicitly on the initial number of enzyme molecules. The accuracy and validity of our approximated results as well as that of our predictions regarding the behaviour of the stochastic enzyme catalytic models are verified by direct simulation of the stochastic model using Gillespie stochastic simulation algorithm.
An approximate solution to the stress and deformation states of functionally graded rotating disks
NASA Astrophysics Data System (ADS)
Sondhi, Lakshman; Sanyal, Shubhashis; Saha, Kashi Nath; Bhowmick, Shubhankar
2016-07-01
The present work employs variational principle to investigate the stress and deformation states and estimate the limit angular speed of functionally graded high-speed rotating annular disks of constant thickness. Assuming a series approximation following Galerkin's principle, the solution of the governing equation is obtained. In the present study, elasticity modulus and density of the disk material are taken as power function of radius with the gradient parameter ranging between 0.0 and 1.0. Results obtained from numerical solutions are validated with benchmark results and are found to be in good agreement. The results are reported in dimensional form and presented graphically. The results provide a substantial insight in understanding the behavior of FGM rotating disks with constant thickness and different gradient parameter. Furthermore, the stress and deformation state of the disk at constant angular speed and limit angular speed is investigated to explain the existence of optimum gradient parameters.
Stationary surgical smoke evacuation systems.
2001-03-01
Two types of systems are available for evacuating the surgical smoke created by electrosurgery and laser surgery: portable and stationary surgical smoke evacuation systems. While portable systems dominate the market today, stationary systems are an alternative worth considering--even though they are still in their infancy, with fewer than 90 systems installed to date. Stationary systems represent a major commitment on the part of the healthcare facility. Several system components must be installed as part of the physical plant (for instance, within the walls), making the system a permanent fixture in the surgical suite. Installation of these systems is often carried out during building construction or major renovation--although the systems can be cost-effective even if no renovations are planned. For this Evaluation, we tested three stationary systems. All three are adequate to capture surgical smoke and evacuate it from the operating room. These systems are easy to use, are quietter than their portable counterparts, and require minimal user maintenance. They represent an excellent option for most hospitals actively evacuating surgical smoke. In this article, we discuss the factors to consider when selecting from among these systems. We also offer guidance on choosing between stationary systems and portable ones. PMID:11321758
The Optimal Solution of a Non-Convex State-Dependent LQR Problem and Its Applications
Xu, Xudan; Zhu, J. Jim; Zhang, Ping
2014-01-01
This paper studies a Non-convex State-dependent Linear Quadratic Regulator (NSLQR) problem, in which the control penalty weighting matrix in the performance index is state-dependent. A necessary and sufficient condition for the optimal solution is established with a rigorous proof by Euler-Lagrange Equation. It is found that the optimal solution of the NSLQR problem can be obtained by solving a Pseudo-Differential-Riccati-Equation (PDRE) simultaneously with the closed-loop system equation. A Comparison Theorem for the PDRE is given to facilitate solution methods for the PDRE. A linear time-variant system is employed as an example in simulation to verify the proposed optimal solution. As a non-trivial application, a goal pursuit process in psychology is modeled as a NSLQR problem and two typical goal pursuit behaviors found in human and animals are reproduced using different control weighting . It is found that these two behaviors save control energy and cause less stress over Conventional Control Behavior typified by the LQR control with a constant control weighting , in situations where only the goal discrepancy at the terminal time is of concern, such as in Marathon races and target hitting missions. PMID:24747417
Fisher, Harvey F
2016-08-01
The transient-state kinetic approach has failed to reach its full potential despite its advantage over the steady-state approach in its ability to observe mechanistic events directly and in real time. This failure has been due in part to the lack of any rigorously derived and readily applicable body of theory corresponding to that which currently characterizes the steady-state approach. In order to clarify the causes of this discrepancy and to suggest a route to its solution we examine the capabilities and limitations of the various forms of transient-state kinetic approaches to the mathematical resolution of enzymatic reaction mechanisms currently available. We document a lack of validity inherent in their basic assumptions and suggest the need for a potentially more rigorous analytic approach. PMID:27173736
On the efficient and reliable numerical solution of rate-and-state friction problems
NASA Astrophysics Data System (ADS)
Pipping, Elias; Kornhuber, Ralf; Rosenau, Matthias; Oncken, Onno
2016-03-01
We present a mathematically consistent numerical algorithm for the simulation of earthquake rupture with rate-and-state friction. Its main features are adaptive time stepping, a novel algebraic solution algorithm involving nonlinear multigrid and a fixed point iteration for the rate-and-state decoupling. The algorithm is applied to a laboratory scale subduction zone which allows us to compare our simulations with experimental results. Using physical parameters from the experiment, we find a good fit of recurrence time of slip events as well as their rupture width and peak slip. Computations in 3-D confirm efficiency and robustness of our algorithm.
Dalsin, Molly C; Tale, Swapnil; Reineke, Theresa M
2014-02-10
Spray dried dispersions (SDDs), solid dispersions of polymer excipients and active pharmaceuticals, are important to the field of oral drug delivery for improving active stability, bioavailability, and efficacy. Herein, we examine the influence of solution-state polymer assemblies on amorphous spray-dried dispersion (SDD) performance with two BCS II model drugs, phenytoin and probucol. These drugs were spray dried with 4 model polymer excipients consisting of poly(ethylene-alt-propylene) (PEP), N,N,-dimethylacrylamide (DMA), or 2-methacrylamido glucopyranose (MAG): amphiphilic diblock ter- and copolymers, PEP-P(DMA-grad-MAG) and PEP-PDMA, and their respective hydrophilic analogues, P(DMA-grad-MAG) and PDMA. Selective and nonselective solvents for the hydrophilic block of the diblock ter- and copolymers were used to induce or repress solution-state assemblies prior to spray drying. Prespray dried solution-state assemblies of these four polymers were probed with dynamic light scattering (DLS) and showed differences in solution assembly size and structure (free polymer versus aggregates versus micelles). Solid-state structures of spray dried dispersions (SDDs) showed a single glass transition event implying a homogeneous mixture of drug/polymer. Crystallization temperatures and enthalpies indicated that the drugs interact mostly with the DMA-containing portions of the polymers. Scanning electron microscopy was used to determine SDD particle size and morphology for the various polymer-drug pairings. In vitro dissolution tests showed excellent performance for one system, spray-dried PEP-PDMA micelles with probucol. Dissolution structures were investigated through DLS to determine drug-polymer aggregates that lead to enhanced SDD performance. Forced aggregation of the polymer into regular micelle structures was found to be a critical factor to increase the dissolution rate and supersaturation maintenance of SDDs, and may be an attractive platform to exploit in excipient
The solution and solid state stability and excipient compatibility of parthenolide in feverfew.
Jin, Ping; Madieh, Shadi; Augsburger, Larry L
2007-01-01
The objectives of this research were to evaluate the stability of parthenolide in feverfew solution state and powdered feverfew (solid state), and explore the compatibility between commonly used excipients and parthenolide in feverfew. Feverfew extract solution was diluted with different pH buffers to study the solution stability of parthenolide in feverfew. Powdered feverfew extract was stored under 40 degrees C/0% approximately 75% relative humidities (RH) or 31% RH/5~50 degrees C to study the influence of temperature and relative humidity on the stability of parthenolide in feverfew solid state. Binary mixtures of feverfew powered extract and different excipients were stored at 50 degrees C/ 75% RH for excipient compatibility evaluation. The degradation of parthenolide in feverfew solution appears to fit a typical first-order reaction. Parthenolide is comparatively stable when the environmental pH is in the range of 5 to 7, becoming unstable when pH is less than 3 or more than 7. Parthenolide degradation in feverfew in the solid state does not fit any obvious reaction model. Moisture content and temperature both play important roles affecting the degradation rate. After 6 months of storage, parthenolide in feverfew remains constant at 5 degrees C/31% RH. However, approximately 40% parthenolide in feverfew can be degraded if stored at 50 degrees C/31% RH. When the moisture changed from 0% to 75% RH, the degradation of parthenolide in feverfew increased from 18% to 32% after 6-month storage under 40 degrees C. Parthenolide in feverfew exhibits good compatibility with commonly used excipients under stressed conditions in a 3-week screening study. PMID:18181526
Positive periodic solutions of periodic neutral Lotka-Volterra system with state dependent delays
NASA Astrophysics Data System (ADS)
Li, Yongkun
2007-06-01
By using a fixed point theorem of strict-set-contraction, some new criteria are established for the existence of positive periodic solutions of the following periodic neutral Lotka-Volterra system with state dependent delays where (i,j=1,2,...,n) are [omega]-periodic functions and (i=1,2,...,n) are [omega]-periodic functions with respect to their first arguments, respectively.
Analytical Solution of Steady State Equations for Chemical Reaction Networks with Bilinear Rate Laws
Halász, Ádám M.; Lai, Hong-Jian; McCabe, Meghan M.; Radhakrishnan, Krishnan; Edwards, Jeremy S.
2014-01-01
True steady states are a rare occurrence in living organisms, yet their knowledge is essential for quasi-steady state approximations, multistability analysis, and other important tools in the investigation of chemical reaction networks (CRN) used to describe molecular processes on the cellular level. Here we present an approach that can provide closed form steady-state solutions to complex systems, resulting from CRN with binary reactions and mass-action rate laws. We map the nonlinear algebraic problem of finding steady states onto a linear problem in a higher dimensional space. We show that the linearized version of the steady state equations obeys the linear conservation laws of the original CRN. We identify two classes of problems for which complete, minimally parameterized solutions may be obtained using only the machinery of linear systems and a judicious choice of the variables used as free parameters. We exemplify our method, providing explicit formulae, on CRN describing signal initiation of two important types of RTK receptor-ligand systems, VEGF and EGF-ErbB1. PMID:24334389
Characters of basic steady state solutions for superfluid Fermi gas in Bessel optical lattices
NASA Astrophysics Data System (ADS)
Zhang, Ke-Zhi; Chen, Yan; He, Yong-Lin; Liu, Zheng-Lai
2015-08-01
We consider a dynamical model for superfluid Fermi gas, trapped in the central well of an axially symmetric Bessel optical lattice potential. The equation includes nonlinear power-law form of the chemical potential μ(n) = C|ψ|2γ, for γ = 2 3, which accounts for Fermi pressure. Reducing the equation to two-dimensional (2D) form, we obtain the basic steady state solutions of the system along the Bose-Einstein condensation (BEC) side to Bardeen-Cooper-Schrieffer (BCS) side by employing the energy balance condition, which are guided by the variational approximation. It is found that the strength ɛ and the radial scale r of the Bessel optical lattice have an extreme effect on the characters of basic steady state solution. Analytically, we deduce the atomic density distribution, the average atom number and the average energy of basic steady state, where the atom distribution of the system presents on periodic change with r, and increases faster at unitarity than in the BEC limit. Furthermore, because of the Fermi pressure, the atomic density distribution at the unitarity is more extensive than that in the BEC limit. In particular, there exist very interesting changes, the average energy intends to collapse state with r, however it emerges as a stable state with varying L both in the BEC limit and at unitarity.
Karunakaran, Venugopal; Prabhu, Deepak D; Das, Suresh; Varughese, Sunil
2015-07-28
Detailed photophysical properties of cyano and mono (MA)/bis alkoxy (DA) substituted diphenylacetylene moieties with different alkyl chain lengths (methyl (1), octyl (8) and dodecyl (12)) were investigated in solution and the solid state in an effort to determine the effect of self-aggregation on these properties. The solvated molecules showed a minimal bathochromic shift with an increase of solvent polarity in their absorption spectra, whereas a significant shift was observed in the emission spectra. This could be attributed to the relatively low change in dipole moment between ground and Franck-Condon excited states and luminescence arising from the intramolecular charge transfer state with a dipole moment significantly higher than that of the ground state. In solid state the emission quantum yields of these materials were significantly higher than in solution. For DA1, polymorphic materials with distinct photophysical properties were obtained. The DA1 materials obtained by fast precipitation (DA1) showed broad fluorescence with peaks at 398, 467 and 535 nm upon excitation at different wavelengths. Detailed analysis of absorption, emission and excitation spectra and lifetime experiments indicated that these peaks could be attributed to the monomer, J- and H-type aggregates respectively. Whereas the crystals obtained by slow crystallization (DA1C) showed only one emission peak at around 396 nm attributed to the monomer. This is supported by the single crystal X-ray structure which consists of a monomer molecule having minimal interaction with nearest neighbour molecules. PMID:26118371
Stationary versus non-stationary (13)C-MFA: a comparison using a consistent dataset.
Noack, Stephan; Nöh, Katharina; Moch, Matthias; Oldiges, Marco; Wiechert, Wolfgang
2011-07-10
Besides the well-established (13)C-metabolic flux analysis ((13)C-MFA) which characterizes a cell's fluxome in a metabolic and isotopic stationary state a current area of research is isotopically non-stationary MFA. Non-stationary (13)C-MFA uses short-time isotopic transient data instead of long-time isotopic equilibrium data and thus is capable to resolve fluxes within much shorter labeling experiments. However, a comparison of both methods with data from one single experiment has not been made so far. In order to create a consistent database for directly comparing both methods a (13)C-labeling experiment in a fed-batch cultivation with a Corynebacterium glutamicum lysine producer was carried out. During the experiment the substrate glucose was switched from unlabeled to a specifically labeled glucose mixture which was immediately traced by fast sampling and metabolite quenching. The time course of labeling enrichments in intracellular metabolites until isotopic stationarity was monitored by LC-MS/MS. The resulting dataset was evaluated using the classical as well as the isotopic non-stationary MFA approach. The results show that not only the obtained relative data, i.e. intracellular flux distributions, but also the more informative quantitative fluxome data significantly depend on the combination of the measurements and the underlying modeling approach used for data integration. Taking further criteria on the experimental and computational part into consideration, the current limitations of both methods are demonstrated and possible pitfalls are concluded. PMID:20638432
Steady-state electrodiffusion. Scaling, exact solution for ions of one charge, and the phase plane.
Leuchtag, H R; Swihart, J C
1977-01-01
This is the first of two papers dealing with electrodiffusion theory (the Nernst-Planck equation coupled with Gauss's law) and its application to the current-voltage behavior of squid axon. New developments in the exact analysis of the steady-state electrodiffusion problem presented here include (a) a scale transformation that connects a given solution to an infinity of other solutions, suggesting the po-sibility of direct comparison of electrical data for membranes with different thicknesses and other properties; (b) a first-integral relation between the electric field and ion densities more general than analogous relations previously reported, and (c) an exact solution for the homovalent system, i.e., a membrane system permeated by various ion species of the same charge. The latter is a generalization of the known one-ion solution. The properties of the homovalent solution are investigated analytically and graphically. In particular we study the phase-plane curves, which reduce to the parabolas discussed by K. S. Cole in the special case in which the current-density parameter (a linear combination of the ionic current densities) is zero. PMID:831855
Structural characterization of NaOH aqueous solution in the glass and liquid states
NASA Astrophysics Data System (ADS)
Bruni, F.; Ricci, M. A.; Soper, A. K.
2001-05-01
Using the technique of hydrogen and deuterium substitution, the structure of water in concentrated NaOH solution (10 M) is explored. It is found that major changes in water structure occur both in the liquid phase at T=300 K and in the glassy phase at T=173 K. In particular the 4.4 Å peak in the OO pair correlation function of pure water, which is normally viewed as indicating tetrahedral short-range coordination in water, is totally absent in the NaOH solution at room temperature, and shows up only as a small feature in the NaOH solution in the glassy state. Corresponding changes occur in the OH and HH correlation functions: The hydrogen bond peak position is shifted from 1.85 Å in pure water to 1.65 Å for both the liquid and glassy NaOH, with a reduced number of hydrogen bonds in the glassy phase. The intramolecular HH distance, 1.5 Å, of the water molecule is unaffected by the presence of the solute, but the positions of the peaks in the HH function at 2.4 and 3.8 Å, due to the orientational correlation between neighboring pure water molecules, are respectively, shifted to 2.15 and 3.5 Å. The above findings indicate that ions in aqueous solutions induce a change in water structure equivalent to the application of high pressures.
Solution- and Adsorbed-State Structural Ensembles Predicted for the Statherin-Hydroxyapatite System
Masica, David L.; Gray, Jeffrey J.
2009-01-01
Abstract We have developed a multiscale structure prediction technique to study solution- and adsorbed-state ensembles of biomineralization proteins. The algorithm employs a Metropolis Monte Carlo-plus-minimization strategy that varies all torsional and rigid-body protein degrees of freedom. We applied the technique to fold statherin, starting from a fully extended peptide chain in solution, in the presence of hydroxyapatite (HAp) (001), (010), and (100) monoclinic crystals. Blind (unbiased) predictions capture experimentally observed macroscopic and high-resolution structural features and show minimal statherin structural change upon adsorption. The dominant structural difference between solution and adsorbed states is an experimentally observed folding event in statherin's helical binding domain. Whereas predicted statherin conformers vary slightly at three different HAp crystal faces, geometric and chemical similarities of the surfaces allow structurally promiscuous binding. Finally, we compare blind predictions with those obtained from simulation biased to satisfy all previously published solid-state NMR (ssNMR) distance and angle measurements (acquired from HAp-adsorbed statherin). Atomic clashes in these structures suggest a plausible, alternative interpretation of some ssNMR measurements as intermolecular rather than intramolecular. This work demonstrates that a combination of ssNMR and structure prediction could effectively determine high-resolution protein structures at biomineral interfaces. PMID:19383454
Wave-Mechanical Properties of Stationary States.
ERIC Educational Resources Information Center
Holden, Alan
This monograph is a review of the quantum mechanical concepts presented in two other monographs, "The Nature of Atoms" and "Bonds Between Atoms," by the same author. It is assumed the reader is familiar with these ideas. The monograph sketches only those aspects of quantum mechanics that are of most direct use in picturing and calculating the…
Global equilibrium and local thermodynamics in stationary spacetimes
NASA Astrophysics Data System (ADS)
Panerai, Rodolfo
2016-05-01
In stationary spacetimes global equilibrium states can be defined, applying the maximum entropy principle, by the introduction of local thermodynamic fields determined solely by geometry. As an example, we study a class of equilibrium states for a scalar field in Einstein's static universe, characterized by inhomogeneous thermodynamic properties and nonvanishing angular momentum.
Silver, Mark A; Cary, Samantha K; Johnson, Jason A; Baumbach, Ryan E; Arico, Alexandra A; Luckey, Morgan; Urban, Matthew; Wang, Jamie C; Polinski, Matthew J; Chemey, Alexander; Liu, Guokui; Chen, Kuan-Wen; Van Cleve, Shelley M; Marsh, Matthew L; Eaton, Teresa M; van de Burgt, Lambertus J; Gray, Ashley L; Hobart, David E; Hanson, Kenneth; Maron, Laurent; Gendron, Frédéric; Autschbach, Jochen; Speldrich, Manfred; Kögerler, Paul; Yang, Ping; Braley, Jenifer; Albrecht-Schmitt, Thomas E
2016-08-26
Berkelium is positioned at a crucial location in the actinide series between the inherently stable half-filled 5f(7) configuration of curium and the abrupt transition in chemical behavior created by the onset of a metastable divalent state that starts at californium. However, the mere 320-day half-life of berkelium's only available isotope, (249)Bk, has hindered in-depth studies of the element's coordination chemistry. Herein, we report the synthesis and detailed solid-state and solution-phase characterization of a berkelium coordination complex, Bk(III)tris(dipicolinate), as well as a chemically distinct Bk(III) borate material for comparison. We demonstrate that berkelium's complexation is analogous to that of californium. However, from a range of spectroscopic techniques and quantum mechanical calculations, it is clear that spin-orbit coupling contributes significantly to berkelium's multiconfigurational ground state. PMID:27563098
Steady-state solutions of a diffusive energy-balance climate model and their stability
NASA Technical Reports Server (NTRS)
Ghil, M.
1975-01-01
A diffusive energy-balance climate model, governed by a nonlinear parabolic partial differential equation, was studied. Three positive steady-state solutions of this equation are found; they correspond to three possible climates of our planet: an interglacial (nearly identical to the present climate), a glacial, and a completely ice-covered earth. Models similar to the main one are considered, and the number of their steady states was determined. All the models have albedo continuously varying with latitude and temperature, and entirely diffusive horizontal heat transfer. The stability under small perturbations of the main model's climates was investigated. A stability criterion is derived, and its application shows that the present climate and the deep freeze are stable, whereas the model's glacial is unstable. The dependence was examined of the number of steady states and of their stability on the average solar radiation.
A modified two-state empirical valence bond model for proton transport in aqueous solutions
Mabuchi, Takuya; Fukushima, Akinori; Tokumasu, Takashi
2015-07-07
A detailed analysis of the proton solvation structure and transport properties in aqueous solutions is performed using classical molecular dynamics simulations. A refined two-state empirical valence bond (aTS-EVB) method, which is based on the EVB model of Walbran and Kornyshev and the anharmonic water force field, is developed in order to describe efficiently excess proton transport via the Grotthuss mechanism. The new aTS-EVB model clearly satisfies the requirement for simpler and faster calculation, because of the simplicity of the two-state EVB algorithm, while providing a better description of diffusive dynamics of the excess proton and water in comparison with the previous two-state EVB models, which significantly improves agreement with the available experimental data. The results of activation energies for the excess proton and water calculated between 300 and 340 K (the temperature range used in this study) are also found to be in good agreement with the corresponding experimental data.
A modified two-state empirical valence bond model for proton transport in aqueous solutions
NASA Astrophysics Data System (ADS)
Mabuchi, Takuya; Fukushima, Akinori; Tokumasu, Takashi
2015-07-01
A detailed analysis of the proton solvation structure and transport properties in aqueous solutions is performed using classical molecular dynamics simulations. A refined two-state empirical valence bond (aTS-EVB) method, which is based on the EVB model of Walbran and Kornyshev and the anharmonic water force field, is developed in order to describe efficiently excess proton transport via the Grotthuss mechanism. The new aTS-EVB model clearly satisfies the requirement for simpler and faster calculation, because of the simplicity of the two-state EVB algorithm, while providing a better description of diffusive dynamics of the excess proton and water in comparison with the previous two-state EVB models, which significantly improves agreement with the available experimental data. The results of activation energies for the excess proton and water calculated between 300 and 340 K (the temperature range used in this study) are also found to be in good agreement with the corresponding experimental data.
NASA Astrophysics Data System (ADS)
Ratushnaya, V. I.; Bedeaux, D.; Kulinskii, V. L.; Zvelindovsky, A. V.
2007-03-01
In our previous papers we proposed a continuum model for the dynamics of the systems of self-propelling particles with conservative kinematic constraints on the velocities. We have determined a class of stationary solutions of this hydrodynamic model and have shown that two types of stationary flow, linear and axially symmetric (vortical) flow, are possible. In this paper we consider the stability properties of these stationary flows. We show, using a linear stability analysis, that the linear solutions are neutrally stable with respect to the imposed velocity and density perturbations. A similar analysis of the stability of the vortical solution is found to be not conclusive.
NASA Astrophysics Data System (ADS)
Novak, Predrag; Pičuljan, Katarina; Hrenar, Tomica; Biljan, Tomislav; Meić, Zlatko
2009-02-01
Hydrogen bonding in salicylaldehyde-4-phenylthiosemicarbazone ( 1) has been studied by using experimental (NMR, Raman and UV spectroscopies) and quantum chemical (DFT) methods. It has been demonstrated that 1 adopted the hydroxy-thione tautomeric form in solution as found also in the solid state and previously indicated by secondary deuterium isotope effects. Apart from the intra-molecular hydrogen bonds new interactions between 1 and solvent molecules were formed as well. Changes in NMR chemical shifts and calculations have pointed towards a formation of inter-molecular three-centered hydrogen bonds in each of the studied complexes involving OH and NH groups of 1 and associated solvent molecules. Stabilization energies of intra-molecular hydrogen bonds were found to decrease with the increase of the solvent polarity. Two-dimensional NOESY spectra indicated conformational changes in solution with respect to the structure observed in the solid state. These were accounted for by a relatively low barrier of the rotation of the N sbnd N single bond thus enabling a molecule to posses a higher conformational flexibility in solution with portions of skewed conformations. The results presented here can help in a better understanding of the role hydrogen bonds can play in bioactivity of related thiosemicarbazone derivatives and their metal complexes.
The finite state projection algorithm for the solution of the chemical master equation.
Munsky, Brian; Khammash, Mustafa
2006-01-28
This article introduces the finite state projection (FSP) method for use in the stochastic analysis of chemically reacting systems. One can describe the chemical populations of such systems with probability density vectors that evolve according to a set of linear ordinary differential equations known as the chemical master equation (CME). Unlike Monte Carlo methods such as the stochastic simulation algorithm (SSA) or tau leaping, the FSP directly solves or approximates the solution of the CME. If the CME describes a system that has a finite number of distinct population vectors, the FSP method provides an exact analytical solution. When an infinite or extremely large number of population variations is possible, the state space can be truncated, and the FSP method provides a certificate of accuracy for how closely the truncated space approximation matches the true solution. The proposed FSP algorithm systematically increases the projection space in order to meet prespecified tolerance in the total probability density error. For any system in which a sufficiently accurate FSP exists, the FSP algorithm is shown to converge in a finite number of steps. The FSP is utilized to solve two examples taken from the field of systems biology, and comparisons are made between the FSP, the SSA, and tau leaping algorithms. In both examples, the FSP outperforms the SSA in terms of accuracy as well as computational efficiency. Furthermore, due to very small molecular counts in these particular examples, the FSP also performs far more effectively than tau leaping methods. PMID:16460146
Unsteady-state transfer of impurities during crystal growth of sucrose in sugarcane solutions
NASA Astrophysics Data System (ADS)
Martins, P. M.; Ferreira, A.; Polanco, S.; Rocha, F.; Damas, A. M.; Rein, P.
2009-07-01
In this work, we present growth rate data of sucrose crystals in the presence of impurities that can be used by both sugar technologists and crystal growth scientists. Growth rate curves measured in a pilot-scale evaporative crystallizer suggest a period of slow growth that follows the seeding of crystals into supersaturated technical solutions. The observed trend was enhanced by adding typical sugarcane impurities such as starch, fructose or dextran to the industrial syrups. Maximum growth rates of sucrose resulted at intermediate rather than high supersaturation levels in the presence of the additives. The effects of the additives on the sucrose solubility and sucrose mass transfer in solution were taken into account to explain the observed crystal growth kinetics. A novel mechanism was identified of unsteady-state adsorption of impurities at the crystal surface and their gradual replacement by the crystallizing solute towards the equilibrium occupation of the active sites for growth. Specifically designed crystallization experiments at controlled supersaturation confirmed this mechanism by showing increasing crystal growth rates with time until reaching a steady-state value for a given supersaturation level and impurity content.
Hydrodynamics of steady state phloem transport with radial leakage of solute
Cabrita, Paulo; Thorpe, Michael; Huber, Gregor
2013-01-01
Long-distance phloem transport occurs under a pressure gradient generated by the osmotic exchange of water associated with solute exchange in source and sink regions. But these exchanges also occur along the pathway, and yet their physiological role has almost been ignored in mathematical models of phloem transport. Here we present a steady state model for transport phloem which allows solute leakage, based on the Navier-Stokes and convection-diffusion equations which describe fluid motion rigorously. Sieve tube membrane permeability Ps for passive solute exchange (and correspondingly, membrane reflection coefficient) influenced model results strongly, and had to lie in the bottom range of the values reported for plant cells for the results to be realistic. This smaller permeability reflects the efficient specialization of sieve tube elements, minimizing any diffusive solute loss favored by the large concentration difference across the sieve tube membrane. We also found there can be a specific reflection coefficient for which pressure profiles and sap velocities can both be similar to those predicted by the Hagen-Poiseuille equation for a completely impermeable tube. PMID:24409189
Are Eddy Covariance series stationary?
Technology Transfer Automated Retrieval System (TEKTRAN)
Spectral analysis via a discrete Fourier transform is used often to examine eddy covariance series for cycles (eddies) of interest. Generally the analysis is performed on hourly or half-hourly data sets collected at 10 or 20 Hz. Each original series is often assumed to be stationary. Also automated ...
Stationary measure in the multiverse
Linde, Andrei; Vanchurin, Vitaly; Winitzki, Sergei E-mail: vitaly@cosmos2.phy.tufts.edu
2009-01-15
We study the recently proposed ''stationary measure'' in the context of the string landscape scenario. We show that it suffers neither from the ''Boltzmann brain'' problem nor from the ''youngness'' paradox that makes some other measures predict a high CMB temperature at present. We also demonstrate a good performance of this measure in predicting the results of local experiments, such as proton decay.
NASA Astrophysics Data System (ADS)
Bernardin, Cédric; Landim, Claudio
2010-12-01
We examine the entropy of stationary nonequilibrium measures of boundary driven symmetric simple exclusion processes. In contrast with the Gibbs-Shannon entropy (Bahadoran in J. Stat. Phys. 126(4-5):1069-1082, 2007; Derrida et al. in J. Stat. Phys. 126(4-5):1083-1108, 2007), the entropy of nonequilibrium stationary states differs from the entropy of local equilibrium states.
Soil and soil solution chemistry under red spruce stands across the northeastern united states
David, M.B.; Lawrence, G.B.
1996-01-01
Red spruce ecosystems in the northeastern United States are of interest because this species is undergoing regional decline. Their underlying soils have been examined closely at only a few sites, and information available on red spruce soils throughout this region is limited.This study was conducted to examine soil and soil solution chemistry at red spruce sites in the northeastern US that encompass the range of soil conditions in which red spruce grow. Soils and soil solutions from Oa and B horizons were obtained over a 2-year period from 12 undisturbed red spruce forests (elevations of 80-975 m) in New York, Vermont, New Hampshire, and Maine. All sites had extremely acid Spodosols (Oa soil pH range 2.56 to 3.11 in 0.01 M CaCl2), with generally low concentrations of base cations and high concentrations of Al on soil exchange sites. There was considerable range in exchange chemistry across the sites, however, with exchangeable Ca in Oa horizons ranging from 2.1 to 21.6 cmolckg-1 and exchangeable Al from 3.6 to 18.3 cmolckg-1. Solution chemistry had high concentrations of DOC in the Oa horizons (1160-15200 ??mol L-1), with higher concentrations in the fall than in the spring, which was probably a reflection of fresh litter inputs. Despite high concentrations of DOC in all solutions, inorganic Al was found in some Oa solutions at concentrations as high as 26 ??mol L-1. Ratios of Ca2+ to inorganic Al concentraturns were less than 1.0 in the Oa horizon of one site, and were well below 1.0 in B horizons of all sites. That soil chemistry was related to soil solution chemistry was demonstrated by solution Al concentrations in the forest floor having significant relationships with pyrophosphate extractable Al, although it was not related in the B horizon. Soil exchangeable Ca/Al ratios in the Oa horizon explained 75% of the variation in solution Ca2+/inorganic Al ratios when mean values were used for each site. Our studies have expanded the range of soil chemical
Steady-state solutions for relativistically strong electromagnetic waves in plasmas.
NASA Technical Reports Server (NTRS)
Max, C. E.
1973-01-01
New steady-state solutions are derived which describe electromagnetic waves strong enough to make plasma ions and electrons relativistic. A two-fluid model is used throughout. The following solutions are studied: (1) linearly polarized waves with phase velocity much greater than c; (2) arbitrarily polarized waves with phase velocity near c, in a cold uniform plasma; (3) circularly polarized waves in a uniform plasma characterized by a scalar pressure tensor. All of these waves are capable of propagating in normally overdense plasmas, due to nonlinearities introduced by relativistic effects. The propagation of relativistically strong waves in a density gradient is examined, for the example of a circularly polarized wave strong enough to make electrons but not ions relativistic. It is shown that such a wave propagates at constant energy flux despite the nonlinearity of the system.
NASA Astrophysics Data System (ADS)
Kobayashi, Motoyasu; Mitamura, Koji; Terada, Masami; Yamada, Norifumi L.; Takahara, Atsushi
2011-01-01
Cationic and zwitterionic polyelectrolyte brushes on quartz substrate were synthesized by surface-initiated atom transfer radical polymerization of 2-(methacryloyloxy)-ethyltrimethylammonium chloride (MTAC) and 2-(methacryloyloxy)ethyl phosphorylcholine (MPC). The effects of ionic strength on brush structure are investigated by neutron reflectivity (NR) in NaCl deuterium oxide (D2O) solutions. We observed that poly(MTAC) chains were drastically shrunk at concentrations above 0.1 M NaCl/D2O, which may be the change in charge-screening effect against ions on poly(MTAC). On the other hand, effect of salt concentration on a swollen state of poly(MPC) brush was negligible, even at the high concentration (5.0 M) close to saturation. The behaviour of poly(MPC) in salt aqueous solution is completely different from that of poly(MTAC), which may arise from the unique interaction properties, neutral nature, and hydrated water structure of phosphorylcholine units.
The transverse magnetic field effect on steady-state solutions of the Bursian diode
NASA Astrophysics Data System (ADS)
Pramanik, Sourav; Ender, A. Ya.; Kuznetsov, V. I.; Chakrabarti, Nikhil
2015-04-01
A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmitted through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.
The transverse magnetic field effect on steady-state solutions of the Bursian diode
Pramanik, Sourav; Chakrabarti, Nikhil
2015-04-15
A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmitted through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.
Predominance of the triketo tautomer in acyldipivaloylmethanes in solution and the solid state
NASA Astrophysics Data System (ADS)
Stilinović, Vladimir; Portada, Tomislav; Kaitner, Branko
2014-04-01
A series of five acyldipivaloylmethanes was prepared and studied with respect to keto-enol tautomerism. In the solid state all the compounds exist as triketo tautomers with the triketo group of approximate C3 symmetry. MNR and IR spectroscopy were employed to study the compounds in a variety of solvents. No diketoenol tautomers were detected in any of the solutions. However, a slow deuteration was noticed in the CD3OD solution of acetyldipivaloylmethane which indicates presence of a minute amount of the enol form of this compound. The predominance of the triketo tautomer in all the compounds was explained by the destabilisation of the enol due to steric repulsions of the bulky tert-butyl substituents.
Stationary entanglement in N-atom subradiant degenerate cascade systems
Borrelli, Massimo; Piovella, Nicola; Paris, Matteo G. A.
2011-01-15
We address ultracold N-atom degenerate cascade systems and show that stationary subradiant states, already observed in the semiclassical regime, also exist in a fully quantum regime and for a small number of atoms. We explicitly evaluate the amount of stationary entanglement for the two-atom configuration and show full inseparability for the three-atom case. We also show that a continuous variable description of the systems is not suitable to detect entanglement due to the non-Gaussianity of subradiant states.
Characterization of stationary and nonstationary behavior in gyrotron oscillators.
Chang, T H; Chen, S H; Barnett, L R; Chu, K R
2001-08-01
The transition from the stationary state to a sequence of nonstationary states in the gyromonotron oscillator is experimentally characterized for the first time. We have also demonstrated the stationary operation of a gyrotron backward-wave oscillator at a beam current far in excess of the generally predicted nonstationary threshold. This difference in nonlinear behavior has been investigated and shown to be fundamental with a comparative analysis of the feedback mechanisms, energy deposition profiles, and field shaping processes involved in these two types of oscillations. PMID:11497832
Arbitrary l-state solutions of the Feynman propagator with the Deng-Fan molecular potential
NASA Astrophysics Data System (ADS)
Diaf, Ahmed
2015-01-01
The bound state solutions of the Feynman propagator with the rotating Deng- Fan molecular potential are presented approximately. An approximation of the centrifugal potential is used and nonlinear space-time transformations are applied. A relation between the original path integral and the Green function of a new quantum soluble system is derived. The energy spectrum and the normalized eigenfunctions are both obtained for the application of this technique to the Deng-Fan molecular potential. Our results are in very good agreement with those found by using numerical and other methods.
NASA Astrophysics Data System (ADS)
Queloz, P.; Rao, P. C.; Rinaldo, A.
2012-12-01
Travel and residence times are well-known descriptors of hydrologic and solute transport in the vadose zone. It has been observed that their probability density functions are stationary only under specific conditions, rarely encountered in natural catchments. This study aims at demonstrating the emergence of non-stationary solute transport in a highly monitored system, and identifying the factors controlling the variations of the observed solute travel-times. 2-meters deep weighing lysimeters are exposed to stochastic rainfall sequences. Multiple derivatives of difluorobenzoate compounds are sequentially injected at different times in the system, and are analyzed in the drainage flux at the bottom outlet and at different depth within the soil profiles. Willow trees planted in the systems create a stochastic soil water deficit by evapotranspiration. As each tracer injected is analytically differentiable from the others, the computation of the tracer breakthrough curves at the lysimeter outlet allows measuring the solute travel-time distributions conditional on the injection time. The observed breakthrough curves display a large variability, emphasizing the effects of the initial conditions at the injection time and the subsequent states encountered in the system on solute transport. Two types of climate have been simulated on the lysimeters. With the precision load cells installed under each lysimeter and the water content probes deployed in the soil profiles, a detailed comparison of the water balance and storage dynamics and their influence on solute transport timing can be done.
A Solution Space for a System of Null-State Partial Differential Equations: Part 3
NASA Astrophysics Data System (ADS)
Flores, Steven M.; Kleban, Peter
2015-01-01
This article is the third of four that completely and rigorously characterize a solution space for a homogeneous system of 2 N + 3 linear partial differential equations (PDEs) in 2 N variables that arises in conformal field theory (CFT) and multiple Schramm-Löwner evolution (SLE κ ). The system comprises 2 N null-state equations and three conformal Ward identities that govern CFT correlation functions of 2 N one-leg boundary operators. In the first two articles (Flores and Kleban, in Commun Math Phys, arXiv:1212.2301, 2012; Commun Math Phys, arXiv:1404.0035, 2014), we use methods of analysis and linear algebra to prove that dim , with C N the Nth Catalan number. Extending these results, we prove in this article that dim and entirely consists of (real-valued) solutions constructed with the CFT Coulomb gas (contour integral) formalism. In order to prove this claim, we show that a certain set of C N such solutions is linearly independent. Because the formulas for these solutions are complicated, we prove linear independence indirectly. We use the linear injective map of Lemma 15 in Flores and Kleban (Commun Math Phys, arXiv:1212.2301, 2012) to send each solution of the mentioned set to a vector in , whose components we find as inner products of elements in a Temperley-Lieb algebra. We gather these vectors together as columns of a symmetric matrix, with the form of a meander matrix. If the determinant of this matrix does not vanish, then the set of C N Coulomb gas solutions is linearly independent. And if this determinant does vanish, then we construct an alternative set of C N Coulomb gas solutions and follow a similar procedure to show that this set is linearly independent. The latter situation is closely related to CFT minimal models. We emphasize that, although the system of PDEs arises in CFT in away that is typically non-rigorous, our treatment of this system here and in Flores and Kleban (Commun Math Phys, arXiv:1212.2301, 2012; Commun Math Phys, arXiv:1404
Zirconium complexes with lactic acid in the solution and solid states
NASA Astrophysics Data System (ADS)
Demkowicz, Paul Andrew
Lactic acid complexes of zirconium are used in a great number of industrial applications. Among these is their use as crosslinking agents for hydraulic fracturing fluids used in secondary oil recovery operations. Because of a poor understanding of zirconium lactate complex chemistry and crosslinking reactions, however, the design of superior fluid systems is often not guided by sound chemical principles and leads to empirical guesswork. Zirconium lactate solutions were characterized using Fourier transform infrared (FT-IR) spectroscopy, 1H, 13C, and 17O nuclear magnetic resonance (NMR) spectroscopy, and potentiometry. The results indicate that lactic acid is coordinated bidentate to zirconium via the alcohol and carboxylate groups. The average number of lactate ligands per zirconium ion is approximately 2 and is demonstrated to be relatively constant from pH 4--9. The lability of the lactate complexes increases as the pH is decreased. The NMR data reveal that there are both large and small complex molecules present in solution, with the size of the complex depending on the extent of zirconium hydrolysis. Large complexes consist of lactic acid coordinated to polynuclear zirconium hydroxy ions. The molecular size of these complexes is sufficient to hinder their tumbling in solution and cause broadening of the measured NMR signals. Small complexes involve lactic acid coordinated to hydroxylated species containing fewer zirconium ions, such that the rotational motion in solution is sufficiently rapid to result in narrow NMR signals. Zirconium lactate complexes were precipitated from solution and analyzed in the solid state using FT-IR spectroscopy, 13C magic angle spinning (MAS) NMR spectroscopy, elemental analysis, thermal gravitational analysis, and x-ray diffraction. Two distinct types of crystalline compounds were synthesized with four lactate ligands per zirconium ion. The coordination of lactic acid to zirconium is different in the two compounds, with one showing
Tracer breakthrough curves in a complex lysimeter system: evidence of non-stationary transport
NASA Astrophysics Data System (ADS)
Queloz, P.; Bertuzzo, E.; Botter, G.; Rao, P.; Rinaldo, A.
2013-12-01
We report on the outcomes of a lysimeter experiment aimed at the measurement of travel time distributions of water and certain nonreactive solutes under non-stationary conditions to examine the kinematics of age mixing. In order to simulate the release of a compound in a receiving water body, it is common in hydrology to attribute a travel time probability distribution to each particle, which reflects the response of a catchment unit to a solute input. Hence, the concentration measured at a control section becomes the convolution between the travel time distribution and the concentration of the inputs throughout the past. This study aims at experimentally demonstrating that the tracer travel time probability distribution is, in fact, strongly dependent on the antecedent conditions at the time of tracer injection and the subsequent states experienced in the system. It is therefore a function of numerous transient processes such as hydrologic filtering in soils, climatic forcing or evapotranspiration patterns. A 2-meter deep weighing lysimeter was equipped with a discharge measurement system coupled with a sample collector, an array of water content sensors and an array of porous cups for soil water sampling at three different depths. Controlled random rainfall following a Poisson process was generated, and evapotranspiration losses from two willow trees planted in the lysimeter created an important soil-water storage deficit. Five species of fluorobenzoic acids were used as tracers, and sequentially injected through rainfall at different times. The measurement system installed allowed a precise and accurate monitoring of every input and output flux and water storage, which is crucial to determine the conditions influencing the travel time distribution and to calculate the mass loads and recovery rates. Breakthrough curves for multiple tracers measured at several depths within the lysimeter and at the lysimeter outlet provide support for non-stationary tracer travel
ATUS-PRO: A FEM-based solver for the time-dependent and stationary Gross-Pitaevskii equation
NASA Astrophysics Data System (ADS)
Marojević, Želimir; Göklü, Ertan; Lämmerzahl, Claus
2016-05-01
ATUS-PRO is a solver-package written in C++ designed for the calculation of numerical solutions of the stationary- and the time dependent Gross-Pitaevskii equation for local two-particle contact interaction utilising finite element methods. These are implemented by means of the deal.II library (Bangerth et al., 0000) [1], (Bangerth et al., 2007) [2]. The code can be used in order to perform simulations of Bose-Einstein condensates in gravito-optical surface traps, isotropic and full anisotropic harmonic traps, as well as for arbitrary trap geometries. A special feature of this package is the possibility to calculate non-ground state solutions (topological modes, excited states) (Marojević et al., 2013), (Yukalov et al., 1997, 2004) [3,4] for an arbitrarily high non-linearity term. The solver-package is designed to run on parallel distributed machines and can be applied to problems in one, two, or three spatial dimensions with axial symmetry or in Cartesian coordinates. The time dependent Gross-Pitaevskii equation is solved by means of the fully implicit Crank-Nicolson method, whereas stationary states are obtained with a modified version based on our own constrained Newton method (Marojević et al., 2013). The latter method enables to find the excited state solutions.
Solution and Solid State Nuclear Magnetic Resonance Spectroscopic Characterization of Efavirenz.
Sousa, Eduardo Gomes Rodrigues de; Carvalho, Erika Martins de; San Gil, Rosane Aguiar da Silva; Santos, Tereza Cristina Dos; Borré, Leandro Bandeira; Santos-Filho, Osvaldo Andrade; Ellena, Javier
2016-09-01
Samples of efavirenz (EFZ) were evaluated to investigate the influence of the micronization process on EFZ stability. A combination of X-ray diffraction, thermal analysis, FTIR, observations of isotropic chemical shifts of (1)H in distinct solvents, their temperature dependence and spin-lattice relaxation time constants (T1), solution (1D and 2D) (13)C nuclear magnetic resonance (NMR), and solid-state (13)C NMR (CPMAS NMR) provides valuable structural information and structural elucidation of micronized EFZ and heptane-recrystallized polymorphs (EFZ/HEPT). This study revealed that the micronization process did not affect the EFZ crystalline structure. It was observed that the structure of EFZ/HEPT is in the same form as that obtained from ethyl acetate/hexane, as shown in the literature. A comparison of the solid-state NMR spectra revealed discrepancies regarding the assignments of some carbons published in the literature that have been resolved. PMID:26886313
Implicit unified gas-kinetic scheme for steady state solutions in all flow regimes
NASA Astrophysics Data System (ADS)
Zhu, Yajun; Zhong, Chengwen; Xu, Kun
2016-06-01
This paper presents an implicit unified gas-kinetic scheme (UGKS) for non-equilibrium steady state flow computation. The UGKS is a direct modeling method for flow simulation in all regimes with the updates of both macroscopic flow variables and microscopic gas distribution function. By solving the macroscopic equations implicitly, a predicted equilibrium state can be obtained first through iterations. With the newly predicted equilibrium state, the evolution equation of the gas distribution function and the corresponding collision term can be discretized in a fully implicit way for fast convergence through iterations as well. The lower-upper symmetric Gauss-Seidel (LU-SGS) factorization method is implemented to solve both macroscopic and microscopic equations, which improves the efficiency of the scheme. Since the UGKS is a direct modeling method and its physical solution depends on the mesh resolution and the local time step, a physical time step needs to be fixed before using an implicit iterative technique with a pseudo-time marching step. Therefore, the physical time step in the current implicit scheme is determined by the same way as that in the explicit UGKS for capturing the physical solution in all flow regimes, but the convergence to a steady state speeds up through the adoption of a numerical time step with large CFL number. Many numerical test cases in different flow regimes from low speed to hypersonic ones, such as the Couette flow, cavity flow, and the flow passing over a cylinder, are computed to validate the current implicit method. The overall efficiency of the implicit UGKS can be improved by one or two orders of magnitude in comparison with the explicit one.
Inverse solution technique of steady-state responses for local nonlinear structures
NASA Astrophysics Data System (ADS)
Wang, Xing; Guan, Xin; Zheng, Gangtie
2016-03-01
An inverse solution technique with the ability of obtaining complete steady-state primary harmonic responses of local nonlinear structures in the frequency domain is proposed in the present paper. In this method, the nonlinear dynamic equations of motion is first condensed from many to only one algebraic amplitude-frequency equation of relative motion. Then this equation is transformed into a polynomial form, and with its frequency as the unknown variable, the polynomial equation is solved by tracing all the solutions of frequency with the increase of amplitude. With this solution technique, some complicated dynamic behaviors such as sharp tuning, anomalous jumps, breaks in responses and detached resonance curves could be obtained. The proposed method is demonstrated and validated through a finite element beam under force excitations and a lumped parameter model with a local nonlinear element under base excitations. The phenomenon of detached resonance curves in the frequency response and its coupling effects with multiple linear modes in the latter example are observed.
Impurity effects in crystal growth from solutions: Steady states, transients and step bunch motion
NASA Astrophysics Data System (ADS)
Ranganathan, Madhav; Weeks, John D.
2014-05-01
We analyze a recently formulated model in which adsorbed impurities impede the motion of steps in crystals grown from solutions, while moving steps can remove or deactivate adjacent impurities. In this model, the chemical potential change of an atom on incorporation/desorption to/from a step is calculated for different step configurations and used in the dynamical simulation of step motion. The crucial difference between solution growth and vapor growth is related to the dependence of the driving force for growth of the main component on the size of the terrace in front of the step. This model has features resembling experiments in solution growth, which yields a dead zone with essentially no growth at low supersaturation and the motion of large coherent step bunches at larger supersaturation. The transient behavior shows a regime wherein steps bunch together and move coherently as the bunch size increases. The behavior at large line tension is reminiscent of the kink-poisoning mechanism of impurities observed in calcite growth. Our model unifies different impurity models and gives a picture of nonequilibrium dynamics that includes both steady states and time dependent behavior and shows similarities with models of disordered systems and the pinning/depinning transition.
Secrets of solid state and aqueous solution structures of [Ni(tmdta)](2-).
Meier, Roland; Platas-Iglesias, Carlos; Heinemann, Frank W; Linti, Gerald; Schulte, Jürgen; Srivastava, Sunil K
2014-07-01
The molecular structures of Li2[Ni(tmdta)]·5H2O (1a, tmdta = trimethylenediaminetetraacetate), {C(NH2)3}2[Ni(tmdta)]·6H2O (1b), and {Ni(H2O)6}[Ni(tmdta)]·2H2O (2a) have been determined. The central trimethylenediamine chelate ring shows half-chair (hc) geometries in 1a and 1b, while a twist-boat (tb) conformation is encountered in 2a. The coexistence of tb and hc forms in the solid state prompted us to elucidate the existence of a tb ⇌ hc equilibrium in aqueous solution. Evaluation of the data from solid state vibrational spectra (Raman and IR) for the hc and tb forms showed excellent agreement with simulated spectra obtained with DFT computations (TPSSh/TZVP). This outstanding matching between theory and experiment enabled us to build composite spectra with varying hc:tb ratios. Comparison of these results with Raman and IR spectra recorded for [Ni(tmdta)](2-) in aqueous solution revealed that simulated Raman and IR spectra with a hc:tb ratio = 2:3 match the solution spectra in an accurate way. This equilibrium ratio enabled us to compute (13)C NMR sifts for the paramagnetic solution spectrum of [Ni(tmdta)](2-) based on the relative contributions by hc and tb fractions. This leads to computed shifts that agree closely with the experimental ones. Also, the kinetics of the skeleton dynamics could be estimated quantitatively by temperature-dependent (13)C NMR spectroscopic measurements. An interesting effect encountered for the very first time here concerns a drastic intensity difference of the 10Dq band ((3)A2g → (3)T2g(F) transition) in solid state electronic spectra of tb vs hc isomers, where the intensity of this band in the case of the hc form is much lower than that of the tb conformer and thus more similar to the case of the usual Ni(II) chromophore in octahedral environment. The equilibrium constants for complex formation and protonation of Ni(II)-tmdta at low pH have been estimated by pH-dependent UV-vis titration experiments. Correlation of these
Lu, Tianfeng; Law, Chung K
2006-12-14
A systematic approach was developed to obtain analytic solutions for the concentrations of the quasi steady state (QSS) species in reduced mechanisms. The nonlinear algebraic equations for the QSS species concentrations were first approximated by a set of linear equations, and the linearized quasi steady state approximations (LQSSA) were then analytically solved with a directed graph, namely a QSSG, which was abstracted from the inter-dependence of QSS species. To obtain analytic solutions of high computational efficiency, the groups of strongly connected QSS species were first identified in the QSSG. The inter group couplings were then resolved by a topological sort, and the inner group couplings were solved with variable elimination by substitution. An efficient algorithm was developed to identify a near-optimal sequence for the variable elimination process. The proposed LQSSA-QSSG method was applied to generate a 16-step reduced mechanism for ethylene/air, and good accuracy and high efficiency were observed in simulations of auto-ignition and perfectly stirred reactors with the reduced mechanism. PMID:17149834
Nominally stationary high-concentration solar optics by gradient-index lenses.
Kotsidas, Panagiotis; Modi, Vijay; Gordon, Jeffrey M
2011-01-31
It is shown how novel solutions for realistic gradient-index lenses create the possibility of nominally stationary solar photovoltaic concentrators capable of daylong averaged flux concentration levels of order 10(3). PMID:21369051
Cornilescu, Gabriel; Ulijasz, Andrew T; Cornilescu, Claudia C; Markley, John L; Vierstra, Richard D
2008-11-01
The unique photochromic absorption behavior of phytochromes (Phys) depends on numerous reversible interactions between the bilin chromophore and the associated polypeptide. To help define these dynamic interactions, we determined by NMR spectroscopy the first solution structure of the chromophore-binding cGMP phosphodiesterase/adenylcyclase/FhlA (GAF) domain from a cyanobacterial Phy assembled with phycocyanobilin (PCB). The three-dimensional NMR structure of Synechococcus OS-B' cyanobacterial Phy 1 in the red-light-absorbing state of Phy (Pr) revealed that PCB is bound to Cys138 of the GAF domain via the A-ring ethylidene side chain and is buried within the GAF domain in a ZZZsyn,syn,anti configuration. The D ring of the chromophore sits within a hydrophobic pocket and is tilted by approximately 80 degrees relative to the B/C rings by contacts with Lys52 and His169. The solution structure revealed remarkable flexibility for PCB and several adjacent amino acids, indicating that the Pr chromophore has more freedom in the binding pocket than anticipated. The propionic acid side chains of rings B and C and Arg101 and Arg133 nearby are especially mobile and can assume several distinct and energetically favorable conformations. Mutagenic studies on these arginines, which are conserved within the Phy superfamily, revealed that they have opposing roles, with Arg101 and Arg133 helping stabilize and destabilize the far-red-light-absorbing state of Phy (Pfr), respectively. Given the fact that the Synechococcus OS-B' GAF domain can, by itself, complete the Pr --> Pfr photocycle, it should now be possible to determine the solution structure of the Pfr chromophore and surrounding pocket using this Pr structure as a framework. PMID:18762196
Non stationary pair model in blazar
NASA Astrophysics Data System (ADS)
Marcowith, Alexandre; Henri, Gilles; Renaud, Nicolas
2001-09-01
This article shortly present an improved version of pair models for X and gamma-ray emission from blazar jets. The radiations are generated through external and synchrotron Inverse Compton mechanisms in the vicinity of a super-massive black hole by an ultra-relativistic electron-positron pair plasma pervading a non-relativistic electron-proton jet (two-flow model). Non stationary solutions are found by solving simultaneously pair creation/annihilation, soft photon absorption and particle acceleration processes along the jet. The power supply necessary to re-accelerate particles is not treated in a self-consistent procedure but parametrised. Pair creation opacity effects can lead to interesting variability effects depending on the X-ray emission regimes. Multi-wavelength observations by INTEGRAL will provide tests for the model, and also for the matter content and variability mechanisms in compact sources.
Advances in numerical solutions to integral equations in liquid state theory
NASA Astrophysics Data System (ADS)
Howard, Jesse J.
Solvent effects play a vital role in the accurate description of the free energy profile for solution phase chemical and structural processes. The inclusion of solvent effects in any meaningful theoretical model however, has proven to be a formidable task. Generally, methods involving Poisson-Boltzmann (PB) theory and molecular dynamic (MD) simulations are used, but they either fail to accurately describe the solvent effects or require an exhaustive computation effort to overcome sampling problems. An alternative to these methods are the integral equations (IEs) of liquid state theory which have become more widely applicable due to recent advancements in the theory of interaction site fluids and the numerical methods to solve the equations. In this work a new numerical method is developed based on a Newton-type scheme coupled with Picard/MDIIS routines. To extend the range of these numerical methods to large-scale data systems, the size of the Jacobian is reduced using basis functions, and the Newton steps are calculated using a GMRes solver. The method is then applied to calculate solutions to the 3D reference interaction site model (RISM) IEs of statistical mechanics, which are derived from first principles, for a solute model of a pair of parallel graphene plates at various separations in pure water. The 3D IEs are then extended to electrostatic models using an exact treatment of the long-range Coulomb interactions for negatively charged walls and DNA duplexes in aqueous electrolyte solutions to calculate the density profiles and solution thermodynamics. It is found that the 3D-IEs provide a qualitative description of the density distributions of the solvent species when compared to MD results, but at a much reduced computational effort in comparison to MD simulations. The thermodynamics of the solvated systems are also qualitatively reproduced by the IE results. The findings of this work show the IEs to be a valuable tool for the study and prediction of
Suparmi, A. Cari, C.; Angraini, L. M.
2014-09-30
The bound state solutions of Dirac equation for Hulthen and trigonometric Rosen Morse non-central potential are obtained using finite Romanovski polynomials. The approximate relativistic energy spectrum and the radial wave functions which are given in terms of Romanovski polynomials are obtained from solution of radial Dirac equation. The angular wave functions and the orbital quantum number are found from angular Dirac equation solution. In non-relativistic limit, the relativistic energy spectrum reduces into non-relativistic energy.
Liu, Yong; Meng, Fangfang; He, Longwei; Yu, Xiaoqiang; Lin, Weiying
2016-07-01
It is found that 2,7-substituted carbazole derivative possesses distinct luminescence features in both aggregate and solution states. In view of this, probe realizes highly sensitive detection of RNA in pure water systems by an aggregation-disaggregation method for the first time. PMID:27346863
High efficiency stationary hydrogen storage
Hynek, S.; Fuller, W.; Truslow, S.
1995-09-01
Stationary storage of hydrogen permits one to make hydrogen now and use it later. With stationary hydrogen storage, one can use excess electrical generation capacity to power an electrolyzer, and store the resultant hydrogen for later use or transshipment. One can also use stationary hydrogen as a buffer at fueling stations to accommodate non-steady fueling demand, thus permitting the hydrogen supply system (e.g., methane reformer or electrolyzer) to be sized to meet the average, rather than the peak, demand. We at ADL designed, built, and tested a stationary hydrogen storage device that thermally couples a high-temperature metal hydride to a phase change material (PCM). The PCM captures and stores the heat of the hydriding reaction as its own heat of fusion (that is, it melts), and subsequently returns that heat of fusion (by freezing) to facilitate the dehydriding reaction. A key component of this stationary hydrogen storage device is the metal hydride itself. We used nickel-coated magnesium powder (NCMP) - magnesium particles coated with a thin layer of nickel by means of chemical vapor deposition (CVD). Magnesium hydride can store a higher weight fraction of hydrogen than any other practical metal hydride, and it is less expensive than any other metal hydride. We designed and constructed an experimental NCM/PCM reactor out of 310 stainless steel in the form of a shell-and-tube heat exchanger, with the tube side packed with NCMP and the shell side filled with a eutectic mixture of NaCL, KCl, and MgCl{sub 2}. Our experimental results indicate that with proper attention to limiting thermal losses, our overall efficiency will exceed 90% (DOE goal: >75%) and our overall system cost will be only 33% (DOE goal: <50%) of the value of the delivered hydrogen. It appears that NCMP can be used to purify hydrogen streams and store hydrogen at the same time. These prospects make the NCMP/PCM reactor an attractive component in a reformer-based hydrogen fueling station.
Hawking radiation of stationary and non-stationary Kerr-de Sitter black holes
NASA Astrophysics Data System (ADS)
Singh, T. Ibungochouba
2015-07-01
Hawking radiation of the stationary Kerr-de Sitter black hole is investigated using the relativistic Hamilton-Jacobi method. Meanwhile, extending this work to a non-stationary black hole using Dirac equations and generalized tortoise coordinate transformation, we derived the locations, the temperature of the thermal radiation as well as the maximum energy of the non-thermal radiation. It is found that the surface gravity and the Hawking temperature depend on both time and different angles. An extra coupling effect is obtained in the thermal radiation spectrum of Dirac particles which is absent from thermal radiation of scalar particles. Further, the chemical potential derived from the thermal radiation spectrum of scalar particle has been found to be equal to the highest energy of the negative energy state of the scalar particle in the non-thermal radiation for the Kerr-de Sitter black hole. It is also shown that for stationary black hole space time, these two different methods give the same Hawking radiation temperature.
Solid-state stability study of meropenem – solutions based on spectrophotometric analysis
2013-01-01
Background B-Lactam antibiotics are still the most common group of chemotherapeutic drugs that are used in the treatment of bacterial infections. However, due to their chemical instability the potential to apply them as oral pharmacotherapeutics is often limited and so it is vital to employ suitable non-destructive analytical methods. Hence, in order to analyze such labile drugs as β-lactam analogs, the application of rapid and reliable analytical techniques which do not require transferring to solutions or using organic solvents, following the current green approach to pharmaceutical analysis, is necessary. The main objective of the present research was to develop analytical methods for the evaluation of changes in meropenem in the solid state during a stability study. Results The UV, FT-IR and Raman spectra of meropenem were recorded during a solid-state stability study. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated according to the density-functional theory (DFT/B3LYP method) with a 6-31G(d,p) basis set. As the differences between the observed and scaled wavenumber values were small, a detailed interpretation of the FT-IR and Raman spectra was possible for non-degraded and degraded samples of meropenem. The problem of the overlapping spectra of meropenem and ring-containing degradation products was solved by measuring changes in the values of the first-derivative amplitudes of the zero-order spectra of aqueous solutions of meropenem. Also, molecular electrostatic potential (MEP), front molecular orbitals (FMOs) and the gap potential between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were determined. Conclusions Based on the findings of this work, it appears possible to use time-saving and reliable spectrophotometric analytical methods, supported by quantum-chemical calculations, for solid-state stability investigations of
STATIONARY COMBUSTION NOX CONTROL: A SUMMARY OF THE 1991 SYMPOSIUM
The paper summarizes the 1991 Symposium on Stationary Combustion NOx (nitrous oxides) Control, held March 25-28, 1991, in Washington, DC. pproximately 500 attended, representing 53 domestic and 13 foreign utility companies, federal and state government agencies, research and deve...
Realization of quantum SWAP gate between flying and stationary qubits
Liang Linmei; Li Chengzu
2005-08-15
This paper presents a scheme to realize the SWAP gate between flying and stationary qubits through cavity QED, which is a necessary condition for networkability of quantum computation. As application, the storage of quantum information and teleportation of atomic and ionic states are present.
Newman-Penrose constants of stationary electrovacuum space-times
Zhang Xiangdong; Gao Sijie; Wu Xiaoning
2009-05-15
A theorem related to the Newman-Penrose constants is proven. The theorem states that all the Newman-Penrose constants of asymptotically flat, stationary, asymptotically algebraically special electrovacuum space-times are zero. Straightforward application of this theorem shows that all the Newman-Penrose constants of the Kerr-Newman space-time must vanish.
Marginally outer trapped surfaces in stationary initial data
NASA Astrophysics Data System (ADS)
Carrasco, A.; Mars, M.
We present two results for bounding marginally outer trapped surfaces (MOTSs) in Killing initial data satisfying the null energy condition and containing an untrapped barrier. The first one applies to the stationary case and states that no bounding MOTS lying in the exterior region where the stationary Killing vector is causal and penetrating into the timelike region can exist. The second result applies to the static case and shows that no bounding MOTS can penetrate into the exterior region where the static Killing vector is timelike. These results extend an interesting theorem by P. Miao (Miao 2005).
Offerman, S.E.; Dijk, N.H. van; Sietsma, J.; Lauridsen, E.M.; Margulies, L.; Grigull, S.; Poulsen, H.F.; Zwaag, S. van der
2004-09-20
A simplified grain growth model is presented for the transition from non-overlapping to overlapping diffusion fields of growing neighboring grains during partitioning solid-state transformations in polycrystalline materials. The model is based on unique observations on the austenite decomposition into ferrite and pearlite in medium-carbon steel with the three-dimensional X-ray diffraction microscope. The model explains three types of observed pro-eutectoid ferrite grain growth and austenite grain decomposition, and the indirectly observed carbon exchange between decomposing austenite grains. A direct comparison of the model and the experiment at the level of individual grains shows that the growth of ferrite grains is strongly related to the local carbon concentration and the local density of nuclei. Unusual observations of a non-stationary austenite grain size prior to the transformation, and oscillatory ferrite growth are reported.
GEL-STATE NMR OF BALL-MILLED WHOLE CELL WALLS IN DMSO-d6 USING 2D SOLUTION-STATE NMR SPECTROSCOPY
Technology Transfer Automated Retrieval System (TEKTRAN)
Plant cell walls were used for obtaining 2D solution-state NMR spectra without actual solubilization or structural modification. Ball-milled whole cell walls were swelled directly in the NMR tube with DMSO-d6 where they formed a gel. There are relatively few gel-state NMR studies. Most have involved...
Schneider, Hans-Jörg
2015-01-01
The lock-and-key concept is discussed with respect to necessary extensions. Formation of supramolecular complexes depends not only, and often not even primarily on an optimal geometric fit between host and guest. Induced fit and allosteric interactions have long been known as important modifications. Different binding mechanisms, the medium used and pH effects can exert a major influence on the affinity. Stereoelectronic effects due to lone pair orientation can lead to variation of binding constants by orders of magnitude. Hydrophobic interactions due to high-energy water inside cavities modify the mechanical lock-and-key picture. That optimal affinities are observed if the cavity is only partially filled by the ligand can be in conflict with the lock-and-key principle. In crystals other forces than those between host and guest often dominate, leading to differences between solid state and solution structures. This is exemplified in particular with calixarene complexes, which by X-ray analysis more often than other hosts show guest molecules outside their cavity. In view of this the particular problems with the identification of weak interactions in crystals is discussed. PMID:25815592
Solution of steady-state, two-dimensional conservation laws by mathematical programming
NASA Technical Reports Server (NTRS)
Lavery, John E.
1991-01-01
A truly two-dimensional algorithm is created for solving the steady-state two-dimensional conservation-law problem. An overdetermined system of algebraic equations is obtained through discretization by finite-volume formulas. These equations are perturbed nonsingularly and are solved by an efficient geometrically oriented l(1) procedure. The basic algorithm and the theory for the linear case f(u) = u are presented, and computational results for the nonlinear case f(u) = sq u are also analyzed. It is noted that the l(1) procedure captures boundary shocks as well as oblige and zigzag interior shocks in bands that are one cell wide, and the solution values are accurate up to the edge of the shock.
Investigating the Mechanisms of Amylolysis of Starch Granules by Solution-State NMR
2015-01-01
Starch is a prominent component of the human diet and is hydrolyzed by α-amylase post-ingestion. Probing the mechanism of this process has proven challenging, due to the intrinsic heterogeneity of individual starch granules. By means of solution-state NMR, we demonstrate that flexible polysaccharide chains protruding from the solvent-exposed surfaces of waxy rice starch granules are highly mobile and that during hydrothermal treatment, when the granules swell, the number of flexible residues on the exposed surfaces increases by a factor of 15. Moreover, we show that these flexible chains are the primary substrates for α-amylase, being cleaved in the initial stages of hydrolysis. These findings allow us to conclude that the quantity of flexible α-glucan chains protruding from the granule surface will greatly influence the rate of energy acquisition from digestion of starch. PMID:25815624
Cho, Herman M.; Felmy, Andrew R.; Craciun, Raluca; Keenum, Johnathan P.; Shah, Neil K.; Dixon, David A.
2006-02-22
Evidence for nine new solution state silicate oligomers has been discovered by 29Si NMR homonuclear correlation experiments of 29Si-enriched samples. In addition to enhancing signal sensitivity, the isotopic enrichment increases the probability of the 29Si–29Si two-bond scalar couplings that are necessary for the observation of internuclear correlations in 2-D experiments. The proposed assignments are validated by comparisons of experimental and simulated crosspeaks obtained with high digital resolution. The internuclear connectivity indicated by the NMR data suggests that several of these oligomers can have multiple stereoisomers, including conformers and/or diastereomers. The stability of these oligomers and their possible stereoisomers have been investigated by electronic structure calculations.
Cho, Herman; Felmy, Andrew R; Craciun, Raluca; Keenum, J Patrick; Shah, Neil; Dixon, David A
2006-02-22
Evidence for nine new solution state silicate oligomers has been discovered by (29)Si NMR homonuclear correlation experiments of (29)Si-enriched samples. In addition to enhancing signal sensitivity, the isotopic enrichment increases the probability of the (29)Si-(29)Si two-bond scalar couplings that are necessary for the observation of internuclear correlations in 2-D experiments. The proposed assignments are validated by comparisons of experimental and simulated cross-peaks obtained with high digital resolution. The internuclear connectivity indicated by the NMR data suggests that several of these oligomers can have multiple stereoisomers, including conformers and/or diastereomers. The stabilities of these oligomers and their possible stereoisomers have been investigated by electronic structure calculations. PMID:16478188
Marušič, Maja; Šket, Primož; Bauer, Lubos; Viglasky, Viktor; Plavec, Janez
2012-01-01
We herein report on the formation and high-resolution NMR solution-state structure determination of a G-quadruplex adopted by d[G3ATG3ACACAG4ACG3] comprised of four G-tracts with the third one consisting of four guanines that are intervened with non-G streches of different lengths. A single intramolecular antiparallel (3+1) G-quadruplex exhibits three stacked G-quartets connected with propeller, diagonal and edgewise loops of different lengths. The propeller and edgewise loops are well structured, whereas the longer diagonal loop is more flexible. To the best of our knowledge, this is the first high-resolution G-quadruplex structure where all of the three main loop types are present. PMID:22532609
Photon emission via surface state at the gold/acetonitrile solution interface
Uosaki, Kohei; Murakoshi, Kei; Kita, Hideaki )
1991-01-24
The emission of light caused by an electron-transfer reaction at a gold electrode in acetonitrile solution containing one of three redox species (benzophenone, trans-stilbene, and benzonitrile) with different redox potentials was studied. The high-energy threshold of the spectrum decreases linearly as the potential of the gold electrode becomes more negative. The peak position with respect to the high-energy threshold of the spectrum varies with electrode potential and is not affected by the redox potential of the electron injection species at the same electrode potential. The emission efficiency also depends on the potential. From these results, the authors proposed that the emission is due to a charge-transfer reaction inverse photoemission (CTRIP) process that takes place via a surface state.
Why are cancer drugs so expensive in the United States, and what are the solutions?
Kantarjian, Hagop; Rajkumar, S Vincent
2015-04-01
High cancer drug prices are a worsening trend in cancer care and are affecting patient care and our health care system. In the United States, the average price of cancer drugs for about a year of therapy increased from $5000 to $10,000 before 2000 to more than $100,000 by 2012, while the average household income has decreased by about 8% in the past decade. Further, although 85% of cancer basic research is funded through taxpayers' money, Americans with cancer pay 50% to 100% more for the same patented drug than patients in other countries. Bound by the Hippocratic Oath, oncologists have a moral obligation to advocate for affordable cancer drugs. In this article, we discuss the high cost of cancer drugs, the reasons for these high prices, the implications for patients and the health care system, and potential solutions to the problem. PMID:25792242
Analysis of lasers as a solution to efficiency droop in solid-state lighting
Chow, Weng W.; Crawford, Mary H.
2015-10-06
This letter analyzes the proposal to mitigate the efficiency droop in solid-state light emitters by replacing InGaN light-emitting diodes (LEDs) with lasers. The argument in favor of this approach is that carrier-population clamping after the onset of lasing limits carrier loss to that at threshold, while stimulated emission continues to grow with injection current. A fully quantized (carriers and light) theory that is applicable to LEDs and lasers (above and below threshold) is used to obtain a quantitative evaluation. The results confirm the potential advantage of higher laser output power and efficiency above lasing threshold, while also indicating disadvantages includingmore » low efficiency prior to lasing onset, sensitivity of lasing threshold to temperature, and the effects of catastrophic laser failure. As a result, a solution to some of these concerns is suggested that takes advantage of recent developments in nanolasers.« less
Analysis of lasers as a solution to efficiency droop in solid-state lighting
Chow, Weng W.; Crawford, Mary H.
2015-10-06
This letter analyzes the proposal to mitigate the efficiency droop in solid-state light emitters by replacing InGaN light-emitting diodes (LEDs) with lasers. The argument in favor of this approach is that carrier-population clamping after the onset of lasing limits carrier loss to that at threshold, while stimulated emission continues to grow with injection current. A fully quantized (carriers and light) theory that is applicable to LEDs and lasers (above and below threshold) is used to obtain a quantitative evaluation. The results confirm the potential advantage of higher laser output power and efficiency above lasing threshold, while also indicating disadvantages including low efficiency prior to lasing onset, sensitivity of lasing threshold to temperature, and the effects of catastrophic laser failure. As a result, a solution to some of these concerns is suggested that takes advantage of recent developments in nanolasers.
Solution- and solid-state NMR studies of GPCRs and their ligands.
Tapaneeyakorn, Satita; Goddard, Alan D; Oates, Joanne; Willis, Christine L; Watts, Anthony
2011-06-01
G protein-coupled receptors (GPCRs) represent one of the major targets of new drugs on the market given their roles as key membrane receptors in many cellular signalling pathways. Structure-based drug design has potential to be the most reliable method for novel drug discovery. Unfortunately, GPCR-ligand crystallisation for X-ray diffraction studies is very difficult to achieve. However, solution- and solid-state NMR approaches have been developed and have provided new insights, particularly focussing on the study of protein-ligand interactions which are vital for drug discovery. This review provides an introduction for new investigators of GPCRs/ligand interactions using NMR spectroscopy. The guidelines for choosing a system for efficient isotope labelling of GPCRs and their ligands for NMR studies will be presented, along with an overview of the different sample environments suitable for generation of high resolution structural information from NMR spectra. PMID:20951674
Spatially Non-uniform Trap State Densities in Solution-Processed Hybrid Perovskite Thin Films.
Draguta, Sergiu; Thakur, Siddharatha; Morozov, Yurii V; Wang, Yuanxing; Manser, Joseph S; Kamat, Prashant V; Kuno, Masaru
2016-02-18
The facile solution-processability of methylammonium lead halide (CH3NH3PbI3) perovskites has catalyzed the development of inexpensive, hybrid perovskite-based optoelectronics. It is apparent, though, that solution-processed CH3NH3PbI3 films possess local emission heterogeneities, stemming from electronic disorder in the material. Herein we investigate the spatially resolved emission properties of CH3NH3PbI3 thin films through detailed emission intensity versus excitation intensity measurements. These studies enable us to establish the existence of nonuniform trap density variations wherein regions of CH3NH3PbI3 films exhibit effective free carrier recombination while others exhibit emission dynamics strongly influenced by the presence of trap states. Such trap density variations lead to spatially varying emission quantum yields and correspondingly impact the performance of both methylammonium lead halide perovskite solar cells and other hybrid perovskite-based devices. Of additional note is that the observed spatial extent of the optical disorder extends over length scales greater than that of underlying crystalline domains, suggesting the existence of other factors, beyond grain boundary-related nonradiative recombination channels, which lead to significant intrafilm optical heterogeneities. PMID:26840877
State of the Art in LP-WAN Solutions for Industrial IoT Services.
Sanchez-Iborra, Ramon; Cano, Maria-Dolores
2016-01-01
The emergence of low-cost connected devices is enabling a new wave of sensorization services. These services can be highly leveraged in industrial applications. However, the technologies employed so far for managing this kind of system do not fully cover the strict requirements of industrial networks, especially those regarding energy efficiency. In this article a novel paradigm, called Low-Power Wide Area Networking (LP-WAN), is explored. By means of a cellular-type architecture, LP-WAN-based solutions aim at fulfilling the reliability and efficiency challenges posed by long-term industrial networks. Thus, the most prominent LP-WAN solutions are reviewed, identifying and discussing the pros and cons of each of them. The focus is also on examining the current deployment state of these platforms in Spain. Although LP-WAN systems are at early stages of development, they represent a promising alternative for boosting future industrial IIoT (Industrial Internet of Things) networks and services. PMID:27196909
Fabrication and Performance of All-Solid-State Chloride Sensors in Synthetic Concrete Pore Solutions
Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei
2010-01-01
One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K+, Ca2+, Na+ and SO42− ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments. PMID:22163467
Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei
2010-01-01
One type of all-solid-state chloride sensor was fabricated using a MnO(2) electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K(+), Ca(2+), Na(+) and SO(4) (2-) ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments. PMID:22163467
State of the Art in LP-WAN Solutions for Industrial IoT Services
Sanchez-Iborra, Ramon; Cano, Maria-Dolores
2016-01-01
The emergence of low-cost connected devices is enabling a new wave of sensorization services. These services can be highly leveraged in industrial applications. However, the technologies employed so far for managing this kind of system do not fully cover the strict requirements of industrial networks, especially those regarding energy efficiency. In this article a novel paradigm, called Low-Power Wide Area Networking (LP-WAN), is explored. By means of a cellular-type architecture, LP-WAN–based solutions aim at fulfilling the reliability and efficiency challenges posed by long-term industrial networks. Thus, the most prominent LP-WAN solutions are reviewed, identifying and discussing the pros and cons of each of them. The focus is also on examining the current deployment state of these platforms in Spain. Although LP-WAN systems are at early stages of development, they represent a promising alternative for boosting future industrial IIoT (Industrial Internet of Things) networks and services. PMID:27196909
NASA Technical Reports Server (NTRS)
Poe, C. H.; Owocki, S. P.; Castor, J. I.
1990-01-01
The steady state solution topology for absorption line-driven flows is investigated for the condition that the Sobolev approximation is not used to compute the line force. The solution topology near the sonic point is of the nodal type with two positive slope solutions. The shallower of these slopes applies to reasonable lower boundary conditions and realistic ion thermal speed v(th) and to the Sobolev limit of zero of the usual Castor, Abbott, and Klein model. At finite v(th), this solution consists of a family of very similar solutions converging on the sonic point. It is concluded that a non-Sobolev, absorption line-driven flow with a realistic values of v(th) has no uniquely defined steady state. To the extent that a pure absorption model of the outflow of stellar winds is applicable, radiatively driven winds should be intrinsically variable.
Pradhan, Tuhin; Gazi, Harun Al Rasid; Biswas, Ranjit
2009-08-07
Temperature dependence of the excited state intramolecular charge transfer reaction of 4-(1-azetidinyl)benzonitrile (P4C) in ethyl acetate (EA), acetonitrile (ACN), and ethanol at several concentrations of lithium perchlorate (LiClO{sub 4}) has been investigated by using the steady state and time resolved fluorescence spectroscopic techniques. The temperature range considered is 267-343 K. The temperature dependent spectral peak shifts and reaction driving force (-{Delta}G{sub r}) in electrolyte solutions of these solvents can be explained qualitatively in terms of interaction between the reactant molecule and ion-atmosphere. Time resolved studies indicate that the decay kinetics of P4C is biexponential, regardless of solvents, LiClO{sub 4} concentrations, and temperatures considered. Except at higher electrolyte concentrations in EA, reaction rates in solutions follow the Arrhenius-type temperature dependence where the estimated activation energy exhibits substantial electrolyte concentration dependence. The average of the experimentally measured activation energies in these three neat solvents is found to be in very good agreement with the predicted value based on data in room temperature solvents. While the rate constant in EA shows a electrolyte concentration induced parabolic dependence on reaction driving force (-{Delta}G{sub r}), the former in ethanol and ACN increases only linearly with the increase in driving force (-{Delta}G{sub r}). The data presented here also indicate that the step-wise increase in solvent reorganization energy via sequential addition of electrolyte induces the ICT reaction in weakly polar solvents to crossover from the Marcus inverted region to the normal region.
Austin, Jane E.
2012-01-01
The main conflicts between Sandhill Cranes (Grus canadensis) and farmers in western United States occur in the Rocky Mountain region during migration and wintering periods. Most crop damage by cranes occurs in mature wheat (Triticum aestivum) and barley (Hordeum vulgare), young shoots of alfalfa (Medicago sativa) and cereal grains, chilies (Capsicum annuum), and silage corn (Zea mays). Damage is related to proximity of crop fields to roost sites and timing of crane concentrations relative to crop maturity or vulnerability. The evolution of conflicts between farmers and cranes and current solutions are described for two areas of the Rocky Mountains used by staging, migrating, or wintering cranes: Grays Lake, Idaho, and the Middle Rio Grande Valley, New Mexico. In both areas, conflicts with growing crane populations were aggravated by losses of wetlands and cropland, proximity of crops to roosts and other wetland areas, changing crop types and practices, and increasing urbanization. At Grays Lake, fall-staging cranes damaged barley fields near an important breeding refuge as well as fields 15-50 km away. In the Middle Rio Grande Valley, migrating and wintering cranes damaged young alfalfa fields, chilies, and silage corn. Solutions in both areas have been addressed through cooperative efforts among federal and state agencies, that manage wetlands and croplands to increase food availability and carrying capacity on public lands, provide hazing programs for private landowners, and strategically target crane hunting to problem areas. Sustaining the success of these programs will be challenging. Areas important to Sandhill Cranes in the western United Sates experience continued loss of habitat and food resources due to urbanization, changes in agricultural crops and practices, and water-use conflicts, which threaten the abilities of both public and private landowners to manage wetlands and croplands for cranes. Conservation of habitats and water resources are important
40 CFR 1048.20 - What requirements from this part apply to excluded stationary engines?
Code of Federal Regulations, 2010 CFR
2010-07-01
... is excluded under § 1048.1(c) as a stationary engine and is not required by 40 CFR part 60, subpart... engine power. (4) State: “THIS ENGINE IS EXCLUDED FROM THE REQUIREMENTS OF 40 CFR PART 1048 AS A “STATIONARY ENGINE” AND THE OWNER/OPERATOR MUST COMPLY WITH THE REQUIREMENTS OF 40 CFR PART 60. INSTALLING...
40 CFR 1048.20 - What requirements from this part apply to excluded stationary engines?
Code of Federal Regulations, 2011 CFR
2011-07-01
... is excluded under § 1048.1(c) as a stationary engine and is not required by 40 CFR part 60, subpart... engine power. (4) State: “THIS ENGINE IS EXCLUDED FROM THE REQUIREMENTS OF 40 CFR PART 1048 AS A “STATIONARY ENGINE” AND THE OWNER/OPERATOR MUST COMPLY WITH THE REQUIREMENTS OF 40 CFR PART 60. INSTALLING...
Passive tracking scheme for a single stationary observer
NASA Astrophysics Data System (ADS)
Chan, Y. T.; Rea, Terry
2001-08-01
While there are many techniques for Bearings-Only Tracking (BOT) in the ocean environment, they do not apply directly to the land situation. Generally, for tactical reasons, the land observer platform is stationary; but, it has two sensors, visual and infrared, for measuring bearings and a laser range finder (LRF) for measuring range. There is a requirement to develop a new BOT data fusion scheme that fuses the two sets of bearing readings, and together with a single LRF measurement, produces a unique track. This paper first develops a parameterized solution for the target speeds, prior to the occurrence of the LRF measurement, when the problem is unobservable. At, and after, the LRF measurement, a BOT formulated as a least squares (LS) estimator then produces a unique LS estimate of the target states. Bearing readings from the other sensor serve as instrumental variables in a data fusion setting to eliminate the bias in the BOT estimator. The result is recursive, unbiased and decentralized data fusion scheme. Results from two simulation experiments have corroborated the theoretical development and show that the scheme is optimal.
Kitamura, Fumi; Sawaguchi, Kana; Mori, Asami; Takagi, Shoji; Suzuki, Takayoshi; Kobayashi, Atsushi; Kato, Masako; Nakajima, Kiyohiko
2015-09-01
We prepared hydrazone-palladium(II) complexes of [PdCl2(HL(n))] and [PdCl(L(n))] (n = 1-3) by the reaction of [PdCl2(cod)] or [PdCl2(PhCN)2] and the hydrazone ligands of HL(n) {N'-(pyridin-2-ylmethylene)picolinohydrazide (HL(1)), N'-[1-(pyridin-2-yl)ethylidene]picolinohydrazide (HL(2)), and N'-[(6-methylpyridin-2-yl)methylene]picolinohydrazide (HL(3))}. The structures of the complexes were determined by X-ray analysis. The hydrazone ligands had κN(py1),κN(imine) and κN(amidate),κN(py2) bidentate coordination modes in [PdCl2(HL(n))] (1, n = 1; 2, n = 2) and in [PdCl2(HL(3))] (3), respectively. In contrast, tridentate coordination modes of κN(py1),κN(imine),κN(py2) and κN(py1),κN(amidate),κN(py2) were observed in [PdCl(L(n))] (4, n = 1; 5, n = 2) and in [PdCl(L(n))] (6, n = 1; 7, n = 2; 8, n = 3). Thermal conversion of complexes 1-3 to complexes 6-8 proceeded in acetonitrile. Complexes 4 and 5 were obtained from complexes 1 and 2, respectively, in a basic acetonitrile solution under dark conditions. Complex 4 reverted immediately to complex 1 in an acidic acetonitrile solution that included hydrochloric acid. However, under room light, in the basic acetonitrile solution that included trimethylamine, complex 4 converted photochemically to complex 6. The thermochromic or vapochromic structure conversion of these complexes also occurred in the solid state. On heating at 180 °C, the color of the crystals of complexes 1, 2, and 3 changed from yellow to orange in the solid state. (1)H NMR and/or UV-vis absorption spectroscopy confirmed that the orange complexes 6-8 were produced. The reddish-orange crystals of complexes 4 and 5 were exposed to hydrogen chloride vapor to yield the yellow products of complexes 1 and 2, respectively. PMID:26305775
Solution and Solid-State Studies of DNA-Programmable Nanoparticle Single Crystals
NASA Astrophysics Data System (ADS)
Auyeung, Evelyn
This thesis lays the foundation for three main areas that have significantly advanced the field of DNA-programmable nanoparticle assembly: (1) the synthesis of nanoparticle superlattices with novel lattice symmetries (2) post-assembly characterization and applications of superlattices that have been transferred from solution to the solid state and (3) the realization of a slow-cooling strategy for synthesizing faceted nanoparticle single crystals. Together, these advances mark a turning point in the evolution of DNA-programmable assembly from a simple proof-of-concept demonstrated in 1996 to a powerful materials development strategy that has inspired many ongoing investigations in fields including catalysis, plasmonics, and electronics. Chapter 1 begins with an overview of controlled crystallization and its importance across fields including chemistry and materials science. This followed by a description of DNA-programmable assembly and a discussion on its advantages as an assembly strategy. Chapter 2 describes a powerful strategy for synthesizing nanoparticle superlattices using a coreless nanoparticle consisting purely of spherically-oriented oligonucleotides. This "three dimensional spacer approach" allows for the synthesis of nanoparticle superlattices with exotic structures, including one with no mineral equivalent. While DNA is a versatile ligand for nanoparticle assembly, the resulting superlattices are only stable in solution. Chapter 3 addresses these limitations and presents a method for transitioning these materials from solution to the solid state through silica encapsulation. This encapsulation process has transformed the ability to interrogate these materials using electron microscopy, and it has enabled all the studies in subsequent chapters of this thesis. In Chapter 4, a slow-cooling crystallization technique is described that allows for the synthesis of single crystalline microcrystals with well-defined facets from DNA-nanoparticle building blocks
A Solution Space for a System of Null-State Partial Differential Equations: Part 4
NASA Astrophysics Data System (ADS)
Flores, Steven M.; Kleban, Peter
2015-01-01
This article is the last of four that completely and rigorously characterize a solution space for a homogeneous system of 2 N + 3 linear partial differential equations in 2 N variables that arises in conformal field theory (CFT) and multiple Schramm-Löwner evolution (SLE). The system comprises 2 N null-state equations and three conformal Ward identities that govern CFT correlation functions of 2 N one-leg boundary operators. In the first two articles (Flores and Kleban in Commun Math Phys, 2012; Flores and Kleban, in Commun Math Phys, 2014), we use methods of analysis and linear algebra to prove that dim , with C N the Nth Catalan number. Using these results in the third article (Flores and Kleban, in Commun Math Phys, 2013), we prove that dim and is spanned by (real-valued) solutions constructed with the Coulomb gas (contour integral) formalism of CFT. In this article, we use these results to prove some facts concerning the solution space . First, we show that each of its elements equals a sum of at most two distinct Frobenius series in powers of the difference between two adjacent points (unless is odd, in which case a logarithmic term may appear). This establishes an important element in the operator product expansion for one-leg boundary operators, assumed in CFT. We also identify particular elements of , which we call connectivity weights, and exploit their special properties to conjecture a formula for the probability that the curves of a multiple-SLE process join in a particular connectivity. This leads to new formulas for crossing probabilities of critical lattice models inside polygons with a free/fixed side-alternating boundary condition, which we derive in Flores et al. (Partition functions and crossing probabilities for critical systems inside polygons, in preparation). Finally, we propose a reason for why the exceptional speeds [certain values that appeared in the analysis of the Coulomb gas solutions in Flores and Kleban (Commun Math Phys, 2013)] and
Synthetic supercontainers exhibit distinct solution versus solid state guest-binding behavior.
Dai, Feng-Rong; Sambasivam, Uma; Hammerstrom, Alex J; Wang, Zhenqiang
2014-05-21
The phase-dependent host-guest binding behavior of a new family of synthetic supercontainers has been probed in homogeneous solution and at liquid-liquid, solid-liquid, and solid-gas interfaces. The synthetic hosts, namely, type II metal-organic supercontainers (MOSCs), are constructed from the assembly of divalent metal ions, 1,4-benzenedicarboxylate (BDC) linker, and sulfonylcalix[4]arene-based container precursors. One member of the MOSCs, MOSC-II-tBu-Ni, which is derived from Ni(II), BDC, and p-tert-butylsulfonylcalix[4]arene (TBSC), crystallizes in the space group R3 and adopts pseudo face-centered cubic (fcc) packing, whereas other MOSCs, including TBSC analogue MOSC-II-tBu-Co, p-tert-pentylsulfonylcalix[4]arene (TPSC) analogues MOSC-II-tPen-Ni/Co, and p-tert-octylsulfonylcalix[4]arene (TOSC) analogues MOSC-II-tOc-Ni/Mg/Co, all crystallize in the space group I4/m and assume a pseudo body-centered cubic (bcc) packing mode. This solid-state structural diversity is nevertheless not reflected in their solution host-guest chemistry, as evidenced by the similar binding properties of MOSC-II-tBu-Ni and MOSC-II-tBu-Co in solution. Both MOSCs show comparable binding constants and adsorb ca. 7 equiv of methylene blue (MB) and ca. 30 equiv of aspirin in chloroform. In contrast, the guest-binding behavior of the MOSCs in solid state reveals much more variations. At the solid-liquid interface, MOSC-II-tBu-Co adsorb ca. 5 equiv of MB from an aqueous solution at a substantially faster rate than MOSC-II-tBu-Ni does. However, at the solid-gas interface, MOSC-II-tBu-Ni has higher gas uptake than MOSC-II-tBu-Co, contradicting their overall porosity inferred from the crystal structures. This discrepancy is attributed to the partial collapse of the solid-state packing of the MOSCs upon solvent evacuation. It is postulated that the degree of porosity collapse correlates with the molecular size of the MOSCs, i.e., the larger the MOSCs, the more severe they suffer from the loss of
NASA Technical Reports Server (NTRS)
Pogorzelski, Ronald J.
2004-01-01
When electronic oscillators are coupled to nearest neighbors to form an array on a hexagonal lattice, the planar phase distributions desired for excitation of a phased array antenna are not steady state solutions of the governing non-linear equations describing the system. Thus the steady state phase distribution deviates from planar. It is shown to be possible to obtain an exact solution for the steady state phase distribution and thus determine the deviation from the desired planar distribution as a function of beam steering angle.
Effects of parity-time symmetry in nonlinear Klein-Gordon models and their stationary kinks.
Demirkaya, A; Frantzeskakis, D J; Kevrekidis, P G; Saxena, A; Stefanov, A
2013-08-01
In this work, we introduce some basic principles of PT-symmetric Klein-Gordon nonlinear field theories. By formulating a particular antisymmetric gain and loss profile, we illustrate that the stationary states of the model do not change. However, the stability critically depends on the gain and loss profile. For a symmetrically placed solitary wave (in either the continuum model or a discrete analog of the nonlinear Klein-Gordon type), there is no effect on the steady state spectrum. However, for asymmetrically placed solutions, there exists a measurable effect of which a perturbative mathematical characterization is offered. It is generally found that asymmetry towards the lossy side leads towards stability, while towards the gain side produces instability. Furthermore, a host of finite size effects, which disappear in the infinite domain limit, are illustrated in connection to the continuous spectrum of the problem. PMID:24032958
Molecular dynamics of excited state intramolecular proton transfer: 3-hydroxyflavone in solution
Bellucci, Michael A.; Coker, David F.
2012-05-21
The ultrafast enol-keto photoisomerization in the lowest singlet excited state of 3-hydroxyflavone is investigated using classical molecular dynamics in conjunction with empirical valence bond (EVB) potentials for the description of intramolecular interactions, and a molecular mechanics and variable partial charge model, dependent on transferring proton position, for the description of solute-solvent interactions. A parallel multi-level genetic program was used to accurately fit the EVB potential energy surfaces to high level ab initio data. We have studied the excited state intramolecular proton transfer (ESIPT) reaction in three different solvent environments: methylcyclohexane, acetonitrile, and methanol. The effects of the environment on the proton transfer time and the underlying mechanisms responsible for the varied time scales of the ESIPT reaction rates are analyzed. We find that simulations with our EVB potential energy surfaces accurately reproduce experimentally determined reaction rates, fluorescence spectra, and vibrational frequency spectra in all three solvents. Furthermore, we find that the ultrafast ESIPT process results from a combination of ballistic transfer, and intramolecular vibrational redistribution, which leads to the excitation of a set of low frequency promoting vibrational modes. From this set of promoting modes, we find that an O-O in plane bend and a C-H out of plane bend are present in all three solvents, indicating that they are fundamental to the ultrafast proton transfer. Analysis of the slow proton transfer trajectories reveals a solvent mediated proton transfer mechanism, which is diffusion limited.
c-Abl Tyrosine Kinase Adopts Multiple Active Conformational States in Solution
2016-01-01
Protein tyrosine kinases of the Abl family have diverse roles in normal cellular regulation and drive several forms of leukemia as oncogenic fusion proteins. In the crystal structure of the inactive c-Abl kinase core, the SH2 and SH3 domains dock onto the back of the kinase domain, resulting in a compact, assembled state. This inactive conformation is stabilized by the interaction of the myristoylated N-cap with a pocket in the C-lobe of the kinase domain. Mutations that perturb these intramolecular interactions result in kinase activation. Here, we present X-ray scattering solution structures of multidomain c-Abl kinase core proteins modeling diverse active states. Surprisingly, the relative positions of the regulatory N-cap, SH3, and SH2 domains in an active myristic acid binding pocket mutant (A356N) were virtually identical to those of the assembled wild-type kinase core, indicating that Abl kinase activation does not require dramatic reorganization of the downregulated core structure. In contrast, the positions of the SH2 and SH3 domains in a clinically relevant imatinib-resistant gatekeeper mutant (T315I) appear to be reconfigured relative to their positions in the wild-type protein. Our results demonstrate that c-Abl kinase activation can occur either with (T315I) or without (A356N) global allosteric changes in the core, revealing the potential for previously unrecognized signaling diversity. PMID:27166638
Baluka, M.; Edelstein, N.; O'Donnell, T. A.
1980-10-01
Spectra have been recorded for solutions in anhydrous hydrogen fluoride (AHF) of uranium and neptunium in oxidation states (III) to (VI). The spectra for U(III), Np(III) and Np(IV) in AHF are very similar to those in acidified aqueous solution, but that for U(IV) suggests that the cationic species is UF{sub 2}{sup 2+}. The AHF spectra for the elements in oxidation states (V) and (VI) are not comparable with those of the formally analogous aqueous solutions, where the elements exist as well-defined dioxo-cations. However, the AHF spectra can be related to spectra in the gas phase, in the solid state or in non-aqueous solvents for each element in its appropriate oxidation state.
Talygin, E A; Zazybo, N A; Zhorzholiany, S T; Krestinich, I M; Mironov, A A; Kiknadze, G I; Bokerya, L A; Gorodkov, A Y; Makarenko, V N; Alexandrova, S A
2016-01-01
New approach to intracardiac blood flow condition analysis based on geometric parameters of left ventricle flow channel has been suggested. Parameters, that used in this method, follow from exact solutions of nonstationary Navier-Stocks equations for selforganized tornado-like flows of viscous incompressible fluid. The main advantage of this method is considering dynamic anatomy of intracardiac cavity and trabeculae relief of left ventricle streamlined surface, both registered in a common mri-process, as flow condition indicator. Calculated quantity options that characterizes blood flow condition can be use as diagnostic criterias for estimation of violation in blood circulation function which entails heart ejection reduction. Developed approach allows to clarify heart jet organization mechanism and estimate the share of the tornado-like flow self-organization in heart ejection structure. PMID:27149823
On the paradox of thermocapillary flow about a stationary bubble
NASA Astrophysics Data System (ADS)
Yariv, Ehud; Shusser, Michael
2006-07-01
When a stationary bubble is exposed to an external temperature gradient, Marangoni stresses at the bubble surface result in fluid motion. A straightforward attempt to calculate the influence of this thermocapillary flow upon the temperature distribution fails to provide a well-behaved solution [Balasubramaniam and Subramanian, Phys. Fluids 16, 3131 (2004)]. This problem is revisited here using a regularization procedure which exploits the qualitative disparity in the long-range flow fields generated by a stationary bubble and a moving one. The regularization parameter is an (exponentially small) artificial bubble velocity, which reflects the inability of any asymptotic expansion to satisfy the condition of exact bubble equilibrium. The solution is obtained using asymptotic matching of two separate Reynolds-number expansions: an inner expansion, valid at the bubble neighborhood, and a remote outer expansion, valid far beyond the familiar Oseen region. This procedure provides a well-behaved solution, which is subsequently used to evaluate the convection-induced correction to the hydrodynamic force exerted on the bubble. The independence of that correction upon the artificial velocity confirms the adequacy of the regularization procedure to describe the stationary-bubble case. The ratio of the calculated force to that pertaining to the classical pure-conduction limit [Young, Goldstein, and Block, J. Fluid Mech. 6, 350 (1959)] is given by 1-Ma/8+o(Ma), where Ma is a radius-based Marangoni number.
On the paradox of thermocapillary flow about a stationary bubble
NASA Astrophysics Data System (ADS)
Yariv, Ehud; Shusser, Michael
2006-11-01
When a stationary bubble is exposed to an external temperature gradient, Marangoni stresses at the bubble surface result in fluid motion. A straight-forward attempt to calculate the influence of this thermocapillary flow upon the temperature distribution fails to provide well-behaved solution [Balasubramaniam & Subramanian, Phys. Fluids 16, 3131 (2004)]. This paradox is resolved here using regularization procedure which exploits the qualitative disparity in the long-range flow fields generated by stationary bubble and moving one. The regularization parameter is an (exponentially small) artificial bubble velocity U, which reflects the inability of any asymptotic expansion to satisfy the condition of exact bubble equilibrium. The solution is obtained using asymptotic matching of two separate Reynolds-number expansions: an inner expansion, valid at the bubble neighborhood, and remote outer expansion, valid far beyond the familiar Oseen region. This procedure provides well-behaved solution, which is subsequently used to evaluate the convection-induced correction to the hydrodynamic force exerted on the bubble. The independence of that correction upon U confirms the adequacy of the regularization procdure to descibe the stationary-bubble case. The ratio of the calculated force to that pertaining to the classical pure-conduction limit [Young, Goldstein Block, J. Fluid Mech. 6, 350 (1959)] is given by 1 - Ma/8+ o(Ma), where Ma is radius-based Marangoni number.
On the V-states for the Generalized Quasi-Geostrophic Equations
NASA Astrophysics Data System (ADS)
Hassainia, Zineb; Hmidi, Taoufik
2015-07-01
We prove the existence of the V-states for the generalized inviscid SQG equations with These structures are special rotating simply connected patches with m-fold symmetry bifurcating from the trivial solution at some explicit values of the angular velocity. This produces, inter alia, an infinite family of non stationary global solutions with uniqueness.
Synthesis, Solution and Solid State Structure of Titanium-Maltol Complex
Lamboy, José L.; Pasquale, Antonio; Rheingold, Arnold. L.; Meléndez, Enrique
2007-01-01
The reaction of Cp2TiCl2 with two equivalents of maltol (3-hydroxy-2-methyl-4-pyrone) in water, at room temperature and pH of 5.4, leads to a complete replacement of Cp and chloride ligands affording, Ti(maltolato)2(OH)2. The complex has been characterized by IR, NMR and ESI-MS spectroscopic and cyclic voltammetry methods. In DMSO-d6 solution, the complex shows two isomers in a ratio of 4:1, in which one OH signal can be identified per isomer. This suggests that in solution the complex is monomeric, most likely a chiral cis-Ti(maltolato)2(OH)2 and trans-Ti(maltolato)2(OH)2. The monomeric nature of the complex (in water/methanol 1:1) was verified by ESI-MS spectroscopy, showing a parent peak at 329 m/z. Electrochemical behavior of Ti(maltolato)2(OH)2 using cyclic voltammetry experiments showed the complex undergoes irreversible reduction in aprotic solvents. In D2O solution, at pH of 8.4, the 1H NMR spectrum of the complex shows a mixture of monomer and tetramer Ti(IV)-maltol complexes in a ratio of 1:1. The crystallization of Ti(maltolato)2(OH)2 at pH of 8.4 leads to the formation of [Ti4(maltolato)8(μ-O4)]•18H2O. A single crystal of [Ti4(maltolato)8(μ-O4)]•18H2O was analyzed by X-ray diffraction methods. The complex crystallizes in a monoclinic space group P2(1)/c with a = 12.617(4) Å, b = 24.058(8) Å, c = 22.686(7) Å, β= 97.678(4)° and V = 6824(4) Å3 for Z = 4. Solid state structure determination of the Ti-maltol complex showed to be tetrameric, containing two bridging oxides (in cis position) and two bidentate maltol ligands per titanium in a pseudo-octahedral coordination geometry. PMID:18425211
Trigonometric bearings-only tracking for a single stationary observer
NASA Astrophysics Data System (ADS)
Rea, Terry; Chan, Y. T.
2002-07-01
A single, stationary observer cannot determine a unique target track with bearings-only measurements. In the land environment, for tactical reasons, the observer typically remains stationary but can measure the target range by a laser rangefinder (LRF). Bearings-only tracking of a non-maneuvering target is a non-linear problem. Solutions by iteration or the extended Kalman filter suffer from a high computation load and possible filter divergence. In contrast, the pseudo-linear formulation permits the application of a linear Kalman filter but the range estimate has a bias, which eliminates through instrumental variables. The development in showed that even though a target track is indeterminate due to a stationary observer, a unique target heading is still available from the bearings-only measurements. Then after an LRF range measurement, Rl, future estimates of target position and velocity become determinant. This paper gives a new tracking scheme for a stationary observer that gives the range estimate as a function of Rl, the target heading and bearings. The estimation equation comes from the trigonometric Law of Sines and is simple to implement. The estimator is unbiased and simulation experiments have shown that the estimates are close to the Cramer-Rao Lower Bound.
A Solution Space for a System of Null-State Partial Differential Equations: Part 2
NASA Astrophysics Data System (ADS)
Flores, Steven M.; Kleban, Peter
2015-01-01
This article is the second of four that completely and rigorously characterize a solution space for a homogeneous system of 2 N + 3 linear partial differential equations in 2 N variables that arises in conformal field theory (CFT) and multiple Schramm-Löwner evolution (SLE). The system comprises 2 N null-state equations and three conformal Ward identities which govern CFT correlation functions of 2 N one-leg boundary operators. In the first article (Flores and Kleban, Commun Math Phys, arXiv:1212.2301, 2012), we use methods of analysis and linear algebra to prove that dim , with C N the Nth Catalan number. The analysis of that article is complete except for the proof of a lemma that it invokes. The purpose of this article is to provide that proof. The lemma states that if every interval among ( x 2, x 3), ( x 3, x 4),…,( x 2 N-1, x 2 N ) is a two-leg interval of (defined in Flores and Kleban, Commun Math Phys, arXiv:1212.2301, 2012), then F vanishes. Proving this lemma by contradiction, we show that the existence of such a nonzero function implies the existence of a non-vanishing CFT two-point function involving primary operators with different conformal weights, an impossibility. This proof (which is rigorous in spite of our occasional reference to CFT) involves two different types of estimates, those that give the asymptotic behavior of F as the length of one interval vanishes, and those that give this behavior as the lengths of two intervals vanish simultaneously. We derive these estimates by using Green functions to rewrite certain null-state PDEs as integral equations, combining other null-state PDEs to obtain Schauder interior estimates, and then repeatedly integrating the integral equations with these estimates until we obtain optimal bounds. Estimates in which two interval lengths vanish simultaneously divide into two cases: two adjacent intervals and two non-adjacent intervals. The analysis of the latter case is similar to that for one vanishing
Marshak Lectureship Talk: Women in Physics in the Baltic States Region: Problems and Solutions
NASA Astrophysics Data System (ADS)
Satkovskiene, Dalia
2008-03-01
In this contribution the gender equality problem in physics will be discussed on the basis of the results obtained implementing the project ``Baltic States Network: Women in Sciences and High Technology'' (BASNET) initiated by Lithuanian women physicists and financed by European Commission. The main goal of BASNET project was creation of the regional Strategy how to deal with women in sciences problem in the Baltic States. It has some stages and the contribution follows them. The first one was in depth sociological study aiming to find out disincentives and barriers women scientists face in their career and work at science and higher education institutions. Analysis of results revealed wide range of problems concerned with science organization, management and financing common for both counterparts. However it also proved the existence of women discrimination in sciences. As main factors influencing women under-representation in Physics was found: the stereotypes existing in the society where physics is assigned to the masculine area of activity; failings of the science management system, where highest positions are distributed not using the institutionalized objective criteria but by voting, where the correctness of majority solutions is anticipated implicitly. In physics where male scientists are the majority (they also usually compose executive boards, committees etc.) results of such a procedures often are unfavorable for women. The same reasons also influence women ``visibility'' in physicist's community and as the consequence possibility to receive needed recourses for their research as well as appropriate presentation of results obtained. The study revealed also the conservatism of scientific community- reluctance to face existing in the scientific society problems and to start solving them. On the basis of the results obtained as well practice of other countries the common strategy of solving women in physics (sciences) in the Baltic States region was
( p, q)-five brane and ( p, q)-string solutions, their bound state and its near horizon limit
NASA Astrophysics Data System (ADS)
Klusoň, Josef
2016-06-01
We determine ( p, q)-string and ( p, q)-five brane solutions of type IIB supergravity using SL (2 , ℤ)-symmetry of the full type IIB superstring theory. We also determine SL (2 , ℤ)-transformed solution corresponding to the bound state of NS5-branes and fundamental strings. Then we analyze its near horizon limit and we show that it leads to the AdS3 × S 3 with mixed fluxes.
Kinetic regimes of polyelectrolyte exchange between the adsorbed state and free solution
NASA Astrophysics Data System (ADS)
Sukhishvili, Svetlana A.; Granick, Steve
1998-10-01
We studied the exchange between the adsorbed state and free solution when polyelectrolyte chains, adsorbed to a solid surface of opposite charge, were displaced by chains of higher charge density. Metastable states of surface composition were extremely long-lived (>2-3 days). The system was a family of poly(1,4 vinyl)pyridines (PVP) with different fractions of charged segments (14%, 48%, and 98% quaternized and the same degree of polymerization); samples were exposed sequentially from aqueous D2O solution to a single silicon oxide substrate at pH where the surface carried a large negative charge (pH=9.2 or 10.5). Measurements were based on Fourier transform infrared spectroscopy in attenuated total reflection (FTIR-ATR). As a first conclusion, we found charge of adsorbed polymer to be conserved during extended exchange times, suggesting that charge at the surface (not mass adsorbed) regulated the dynamics of adsorption and desorption. Except at the highest ionic strength charge of polymer at the surface during the displacement process considerably exceeded that for the initially-adsorbed layer, suggesting an intermediate state in which newly-adsorbed chains were more extended from the surface and not yet equilibrated in their conformations. Second, we concluded that desorption was the rate-limiting step in adsorption-desorption, since the desorption rate responded more to changes of ionic strength than did the adsorption rate onto previously-adsorbed polymer. Ionic strength appeared to modulate the intensity of sticking to the surface. Third, we found that the initial stages of desorption obeyed a simple functional form, exponential in the square root of elapsed time. This is conclusively slower than a first-order kinetic process and suggests that desorption in this polyelectrolyte system was diffusion-controlled during the initial stages. It is the same functional form observed for flexible polymers in nonpolar solvents. Fourth, we concluded that at relatively low
NASA Technical Reports Server (NTRS)
Rogers, S. E.; Kwak, D.; Chang, J. L. C.
1986-01-01
The method of pseudocompressibility has been shown to be an efficient method for obtaining a steady-state solution to the incompressible Navier-Stokes equations. Recent improvements to this method include the use of a diagonal scheme for the inversion of the equations at each iteration. The necessary transformations have been derived for the pseudocompressibility equations in generalized coordinates. The diagonal algorithm reduces the computing time necessary to obtain a steady-state solution by a factor of nearly three. Implicit viscous terms are maintained in the equations, and it has become possible to use fourth-order implicit dissipation. The steady-state solution is unchanged by the approximations resulting from the diagonalization of the equations. Computed results for flow over a two-dimensional backward-facing step and a three-dimensional cylinder mounted normal to a flat plate are presented for both the old and new algorithms. The accuracy and computing efficiency of these algorithms are compared.
NASA Astrophysics Data System (ADS)
Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.
2014-12-01
Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two new explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess clear advantages over available alternatives, including: (i) the new solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the new analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.
Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Hu, Hanlin; Amassian, Aram
2016-08-01
We demonstrate that local and long-range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the substrate with solution-state disentanglement and preaggregation of P3HT in a θ solvent, leading to a very significant enhancement of the field effect carrier mobility. The preaggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of preaggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of preaggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to unaggregated polymer chains in the same conditions. Additional measurements reveal the combined preaggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known preaggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties. PMID:27410517
Dual ASE from the monomeric and excimeric states of a conjugated-polymer (PDHF) in solution
NASA Astrophysics Data System (ADS)
Ibnaouf, K. H.
2013-12-01
In this work, the spectral and amplified spontaneous emission (ASE) properties of a conjugated polymer poly [9, 9-di-(2‧-ethylhexyl) fluorenyl-2, 7-diyl] (PDHF) in tetrahydrofuran (THF) have been studied. Our results showed that the absorption spectra of PDHF in THF have only one peak under wide range of concentrations (0.012 mol/m3 to 0.39 mol/m3), it could be seen that the shape of the absorption did not change; this indicates no dimer formation in these solutions for all concentrations mentioned above. On the other hand, the fluorescence spectra of PDHF in THF, at low concentration, showed two peaks, the primary at 415 nm and the secondary at 435 nm. The effects of concentration and the temperature on PDHF in THF under same conditions were studied. For example, the intensity of the peak at 435 nm became increasingly stronger for higher concentration and lower temperature. These are analogs to the excimeric behavior of organic molecules. Under high power pulsed laser excitation, we observed ASE at 418 nm and 437 nm. These ASE peaks could arise from the monomer and excimer states of the macromolecule respectively. The ASE spectra of PDHF were compared with the rhodamine 6 G (Rh 6 G). The most important and distinguishing features are that PDHF has a two times better photochemical stability than rhodamine 6 G and high optical gain compared with the conventional laser dyes.
Outbreaks caused by sprouts, United States, 1998-2010: lessons learned and solutions needed.
Dechet, Amy M; Herman, Karen M; Chen Parker, Cary; Taormina, Peter; Johanson, Joy; Tauxe, Robert V; Mahon, Barbara E
2014-08-01
After a series of outbreaks associated with sprouts in the mid-1990s, the U.S. Food and Drug Administration (FDA) published guidelines in 1999 for sprouts producers to reduce the risk of contamination. The recommendations included treating seeds with an antimicrobial agent such as calcium hypochlorite solution and testing spent irrigation water for pathogens. From 1998 through 2010, 33 outbreaks from seed and bean sprouts were documented in the United States, affecting 1330 reported persons. Twenty-eight outbreaks were caused by Salmonella, four by Shiga toxin-producing Escherichia coli, and one by Listeria. In 15 of the 18 outbreaks with information available, growers had not followed key FDA guidelines. In three outbreaks, however, the implicated sprouts were produced by firms that appeared to have implemented key FDA guidelines. Although seed chlorination, if consistently applied, reduces pathogen burden on sprouts, it does not eliminate the risk of human infection. Further seed and sprouts disinfection technologies, some recently developed, will be needed to enhance sprouts safety and reduce human disease. Improved seed production practices could also decrease pathogen burden but, because seeds are a globally distributed commodity, will require international cooperation. PMID:25076040
Gerlach, Robin
2014-10-31
Background. The use of biological and chemical processes that degrade or immobilize contaminants in subsurface environments is a cornerstone of remediation technology. The enhancement of biological and chemical processes in situ, involves the transport, displacement, distribution and mixing of one or more reactive agents. Biological and chemical reactions all require diffusive transport of solutes to reaction sites at the molecular scale and accordingly, the success of processes at the meter-scale and larger is dictated by the success of phenomena that occur at the micron-scale. However, current understanding of scaling effects on the mixing and delivery of nutrients in biogeochemically dynamic porous media systems is limited, despite the limitations this imposes on the efficiency and effectiveness of the remediation challenges at hand. Objectives. We therefore proposed to experimentally characterize and computationally describe the growth, evolution, and distribution of microbial activity and mineral formation as well as changes in transport processes in porous media that receive two or more reactive amendments. The model system chosen for this project was based on a method for immobilizing 90Sr, which involves stimulating microbial urea hydrolysis with ensuing mineral precipitation (CaCO3), and co-precipitation of Sr. Studies at different laboratory scales were used to visualize and quantitatively describe the spatial relationships between amendment transport and consumption that stimulate the production of biomass and mineral phases that subsequently modify the permeability and heterogeneity of porous media. Biomass growth, activity, and mass deposition in mixing zones was investigated using two-dimensional micro-model flow cells as well as flow cells that could be analyzed using synchrotron-based x-ray tomography. Larger-scale flow-cell experiments were conducted where the spatial distribution of media properties, flow, segregation of biological activity and
Hydrodynamic limit with geometric correction of stationary Boltzmann equation
NASA Astrophysics Data System (ADS)
Wu, Lei
2016-05-01
We consider the hydrodynamic limit of a stationary Boltzmann equation in a unit plate with in-flow boundary. The classical theory claims that the solution can be approximated by the sum of interior solution which satisfies steady incompressible Navier-Stokes-Fourier system, and boundary layer derived from Milne problem. In this paper, we construct counterexamples to disprove such formulation in L∞ both for its proof and result. Also, we show the hydrodynamic limit with a different boundary layer expansion with geometric correction.
Uniqueness of the Stationary Wave for the Extended Fisher-Kolmogorov Equation
NASA Astrophysics Data System (ADS)
Kwapisz, Jaroslaw
2000-07-01
The extended Fisher-Kolmogorov equation, ut=-βuxxxx+uxx+u-u3, β>0, models a binary system near the Lifshitz critical point and is known to exhibit a stationary heteroclinic solution joining the equilibria ±1. For the classical case, β=0, the heteroclinic is u(x)=tanh(x/2) and is unique up to the obvious symmetries. We prove the conjecture that the uniqueness persists all the way to β=1/8, where the onset of spatial chaos associated with the loss of monotonicity of the stationary wave is known to occur. Our methods are non-perturbative and employ a global cross-section to the Hamiltonian flow of the stationary fourth order equation on the energy level of ±1. We also prove uniform a priori bounds on all bounded stationary solutions, valid for any β>0.
Jablan, Jasna; Szalontai, Gábor; Jug, Mario
2012-12-01
The aim of this work was to investigate the potential synergistic effect of water-soluble polymers (hypromellose, HPMC and polyvinylpyrrolidone, PVP) on zaleplon (ZAL) complexation with parent β-cyclodextrin (βCD) and its randomly methylated derivative (RAMEB) in solution and in solid state. The addition of HPMC to the complexation medium improved ZAL complexation and solubilization with RAMEB (K(ZAL/RAMEB)=156±5M(-1) and K(ZAL/RAMEB/HPMC)=189±8M(-1); p<0.01), while such effect was not observed for βCD (K(ZAL/βCD)=112±2M(-1) and K(ZAL/βCD/HPMC)=119±8M(-1); p>0.05). Although PVP increased the ZAL aqueous solubility from 0.22 to 0.27mg/mL, it did not show any synergistic effects on ZAL solubilization with the cyclodextrins tested. Binary and ternary systems of ZAL with βCD, RAMEB and HPMC were prepared by spray-drying. Differential scanning calorimetry, X-ray powder diffraction and scanning electron microscopy demonstrated a partial ZAL amorphization in spray-dried binary and ternary systems with βCD, while the drug was completely amorphous in all samples with RAMEB. Furthermore, inclusion complex formation in all systems prepared was confirmed by solid-state NMR spectroscopy. The in vitro dissolution rate followed the rank order ZAL/RAMEB/HPMC>ZAL/RAMEB=ZAL/βCD/HPMC>ZAL/βCD≫ZAL, clearly demonstrating the superior performance of RAMEB on ZAL complexation in the solid state and its synergistic effect with HPMC on drug solubility. Surprisingly, when loaded into tablets made with insoluble microcrystalline cellulose, RAMEB complexes had no positive effect on drug dissolution, because HPMC and RAMEB acted as a binders inside the tablets, prolonging their disintegration. Oppositely, the formulation with mannitol, a soluble excipient, containing a ternary RAMEB system, released the complete drug-dose in only 5min, clearly demonstrating its suitability for the development of immediate-release oral formulation of ZAL. PMID:22898722
Extracting stationary segments from non-stationary synthetic and cardiac signals
NASA Astrophysics Data System (ADS)
Rodríguez, María. G.; Ledezma, Carlos A.; Perpiñán, Gilberto; Wong, Sara; Altuve, Miguel
2015-01-01
Physiological signals are commonly the result of complex interactions between systems and organs, these interactions lead to signals that exhibit a non-stationary behaviour. For cardiac signals, non-stationary heart rate variability (HRV) may produce misinterpretations. A previous work proposed to divide a non-stationary signal into stationary segments by looking for changes in the signal's properties related to changes in the mean of the signal. In this paper, we extract stationary segments from non-stationary synthetic and cardiac signals. For synthetic signals with different signal-to-noise ratio levels, we detect the beginning and end of the stationary segments and the result is compared to the known values of the occurrence of these events. For cardiac signals, RR interval (cardiac cycle length) time series, obtained from electrocardiographic records during stress tests for two populations (diabetic patients with cardiovascular autonomic neuropathy and control subjects), were divided into stationary segments. Results on synthetic signals reveal that the non-stationary sequence is divided into more stationary segments than needed. Additionally, due to HRV reduction and exercise intolerance reported on diabetic cardiovascular autonomic neuropathy patients, non-stationary RR interval sequences from these subjects can be divided into longer stationary segments compared to the control group.
A Novel Vehicle Stationary Detection Utilizing Map Matching and IMU Sensors
Reaz, Mamun Bin Ibne; Nasir, Salwa Sheikh; Bhuiyan, Mohammad Arif Sobhan; Ali, Mohd. Alauddin Mohd.
2014-01-01
Precise navigation is a vital need for many modern vehicular applications. The global positioning system (GPS) cannot provide continuous navigation information in urban areas. The widely used inertial navigation system (INS) can provide full vehicle state at high rates. However, the accuracy diverges quickly in low cost microelectromechanical systems (MEMS) based INS due to bias, drift, noise, and other errors. These errors can be corrected in a stationary state. But detecting stationary state is a challenging task. A novel stationary state detection technique from the variation of acceleration, heading, and pitch and roll of an attitude heading reference system (AHRS) built from the inertial measurement unit (IMU) sensors is proposed. Besides, the map matching (MM) algorithm detects the intersections where the vehicle is likely to stop. Combining these two results, the stationary state is detected with a smaller timing window of 3 s. A longer timing window of 5 s is used when the stationary state is detected only from the AHRS. The experimental results show that the stationary state is correctly identified and the position error is reduced to 90% and outperforms previously reported work. The proposed algorithm would help to reduce INS errors and enhance the performance of the navigation system. PMID:25276855
Variational Study of SU(3) Gauge Theory by Stationary Variance
NASA Astrophysics Data System (ADS)
Siringo, Fabio
2015-07-01
The principle of stationary variance is advocated as a viable variational approach to gauge theories. The method can be regarded as a second-order extension of the Gaussian Effective Potential (GEP) and seems to be suited for describing the strong-coupling limit of non-Abelian gauge theories. The single variational parameter of the GEP is replaced by trial unknown two-point functions, with infinite variational parameters to be optimized by the solution of a set of coupled integral equations. The stationary conditions can be easily derived by the self-energy, without having to write the effective potential, making use of a general relation between self-energy and functional derivatives that has been proven to any order. The low- energy limit of pure Yang-Mills SU(3) gauge theory has been studied in Feynman gauge, and the stationary equations are written as integral equations for the gluon and ghost propagators. A physically sensible solution is found for any strength of the coupling. The gluon propagator is finite in the infrared, with a dynamical mass that decreases as a power at high energies. At variance with some recent findings in Feynman gauge, the ghost dressing function does not vanish in the infrared limit and a decoupling scenario emerges as recently reported for the Landau gauge.
NASA Astrophysics Data System (ADS)
Ikot, Akpan N.; Maghsoodi, Elham; Hassanabadi, Hassan; Obu, Joseph A.
2014-05-01
In this paper, we obtain the approximate analytical bound-state solutions of the Dirac particle with the generalized Yukawa potential within the framework of spin and pseudospin symmetries for the arbitrary к state with a generalized tensor interaction. The generalized parametric Nikiforov-Uvarov method is used to obtain the energy eigenvalues and the corresponding wave functions in closed form. We also report some numerical results and present figures to show the effect of the tensor interaction.
Stationary patterns for an adsorbate-induced phase transition model: II. Shadow system
NASA Astrophysics Data System (ADS)
Kuto, Kousuke; Tsujikawa, Tohru
2013-05-01
This paper is concerned with stationary solutions of a reaction-diffusion-advection system arising in surface chemistry. Hildebrand et al (2003 New J. Phys. 5 61) have constructed stationary stripe (or spot) solutions of the system in the singular perturbation case and shown a numerical result that the set of stripe (or spot) solutions forms a saddle-node bifurcation curve with respect to a diffusion coefficient. In this paper, we introduce a shadow system in the limiting case that another diffusion and an advection coefficient tend to infinity. Furthermore we obtain the bifurcation structure of stationary solutions of the shadow systems in the one-dimensional case. This structure involves saddle-node bifurcation curves which support the above numerical result in Hildebrand et al (2003 New J. Phys. 5 61, figure 9). Our proof is based on the combination of the bifurcation, the singular perturbation and a level set analysis.
Space plasma physics: I - Stationary processes
NASA Technical Reports Server (NTRS)
Hasegawa, Akira; Sato, Tetsuya
1989-01-01
The physics of stationary processes in space plasmas is examined theoretically in an introduction intended for graduate students. The approach involves the extensive use of numerical simulations. Chapters are devoted to fundamental principles, small-amplitude waves, and the stationary solar plasma system; typical measurement data and simulation results are presented graphically.
Stationary Engineering Laboratory--2. Teacher's Guide.
ERIC Educational Resources Information Center
Steingress, Frederick M.; Frost, Harold J.
The Stationary Engineering Laboratory Manual 2 Teacher's Guide was designed as an aid to the instructors of vocational-technical high school students who have received instruction in the basics of stationary engineering. The course of study was developed for students who will be operating a live plant and who will be responsible for supplying…
Periodic motions (close to stationary) of an axisymmetric satellite with magnetic damping
NASA Technical Reports Server (NTRS)
Ovchinnikov, M. Y.
1983-01-01
Close to stationary periodic motions of an axisymmetric satellite in a circular orbit are considered. The satellite was equipped with a spherical magnetic damper. The investigation was conducted on the assumption that a strong magnet was installed on the damper float. Stationary rotations of the satellite around the axis of symmetry are selected as the generating solutions. The solutions are constructed in the form of power series of the smaller parameter, and they are extended numerically to the region of random values of the damping coefficient. The stability of the resulting solutions was investigated.
Code of Federal Regulations, 2010 CFR
2010-07-01
... Ignition Stationary RICE Located at Area Sources of HAP Emissions 2d Table 2d to Subpart ZZZZ of Part 63... Stationary RICE Located at Area Sources of HAP Emissions As stated in §§ 63.6600 and 63.6640, you must comply with the following emission and operating limitations for existing compression ignition stationary...
Code of Federal Regulations, 2010 CFR
2010-07-01
... Ignition Stationary Rice Located at Major Sources of HAP Emissions 2c Table 2c to Subpart ZZZZ of Part 63... Stationary Rice Located at Major Sources of HAP Emissions As stated in §§ 63.6600 and 63.6640, you must comply with the following requirements for existing compression ignition stationary RICE: For...
Pressure-volume equation of state for pyrope-almandine solid solutions
NASA Astrophysics Data System (ADS)
Nestola, Fabrizio; Milani, Sula; Angel, Ross J.; Pasqual, Daria; Geiger, Charles A.
2013-04-01
Garnet is a key phase of Earth's upper mantle and one of the most abundant solid inclusions in diamonds. The pyrope component (Mg3Al2Si3O12, Py) of garnet found in diamonds of peridotitic and eclogitic origin can be as high as about 79 and 43%, respectively and the almandine component (Fe3Al2Si3O12, Al) is about 11 and 33%, respectively. Thus such garnets are largely Py-Al-rich solid solutions (Stachel and Harris, 2008). To determine the depth of formation of diamond-inclusion pairs, precise and accurate thermoelastic parameters for both the diamond and the solid inclusion phase are necessary (e.g. Izraeli et al., 1999; Howell et al., 2010; Nestola et al., 2011; Howell et al., 2012). We are presently investigating the pressure-volume equation of state for a series of synthetic garnets along the binary pyrope-almandine by X-ray single-crystal diffraction using a diamond anvil cell up to a maximum of 8 GPa pressure. We have completed measurements on two crystals of composition Fe3Al2Si3O12 and Fe1.20Mg1.80Al2Si3O12. The equation of state coefficients obtained by fitting a third-order Birch-Murnaghan to the pressure-volume data show that an increase in the pyrope component in garnet causes a slight decrease of the isothermal bulk modulus, KT0, by about 3%, whereas the first pressure derivative term does not vary. Applying our results to obtain the pressure of formation of a natural diamond-garnet pair, and assuming a garnet composition close to Fe1.20Mg1.80Al2Si3O12, we obtain a pressure of encapsulation (or formation if garnet and diamond are syngenetic) of garnet in diamond between 6.5 and 7.0 GPa. References Howell, D., Wood, I.G., Dobson, D.P., Jones, A.P., Nasdala, L., Harris, J.W. (2010) Contrib. Mineral. Petrol., 160, 705-717. Howell, D., Wood, I.G., Nestola, F., Nimis, P., Nasdala, L. (2012) Eur. J. Mineral., ,. Izraeli, E.S., Harris, J.W., Navon, O. (1999) Earth Planet Sci. Lett., 173, 351-360. Nestola, F., Nimis, P., Ziberna, L., Longo, M., Marzoli, A
Model of non-stationary, inhomogeneous turbulence
NASA Astrophysics Data System (ADS)
Bragg, Andrew D.; Kurien, Susan; Clark, Timothy T.
2016-07-01
We compare results from a spectral model for non-stationary, inhomogeneous turbulence (Besnard et al. in Theor Comp Fluid Dyn 8:1-35, 1996) with direct numerical simulation (DNS) data of a shear-free mixing layer (SFML) (Tordella et al. in Phys Rev E 77:016309, 2008). The SFML is used as a test case in which the efficacy of the model closure for the physical-space transport of the fluid velocity field can be tested in a flow with inhomogeneity, without the additional complexity of mean-flow coupling. The model is able to capture certain features of the SFML quite well for intermediate to long times, including the evolution of the mixing-layer width and turbulent kinetic energy. At short-times, and for more sensitive statistics such as the generation of the velocity field anisotropy, the model is less accurate. We propose two possible causes for the discrepancies. The first is the local approximation to the pressure-transport and the second is the a priori spherical averaging used to reduce the dimensionality of the solution space of the model, from wavevector to wavenumber space. DNS data are then used to gauge the relative importance of both possible deficiencies in the model.
Stationary shapes of confined rotating magnetic liquid droplets.
Lira, Sérgio A; Miranda, José A; Oliveira, Rafael M
2010-09-01
We study the family of steady shapes which arise when a magnetic liquid droplet is confined in a rotating Hele-Shaw cell and subjected to an azimuthal magnetic field. Two different scenarios are considered: first, the magnetic fluid is assumed to be a Newtonian ferrofluid, and then it is taken as a viscoelastic magnetorheological fluid. The influence of the distinct material properties of the fluids on the ultimate morphology of the emerging stationary patterns is investigated by using a vortex-sheet formalism. Some of these exact steady structures are similar to the advanced time patterns obtained by existing time-evolving numerical simulations of the problem. A weakly nonlinear approach is employed to examine this fact and to gain analytical insight about relevant aspects related to the stability of such exact stationary solutions. PMID:21230182
NASA Astrophysics Data System (ADS)
Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; Johnson, Mark R.; Parsegian, V. Adrian
2014-11-01
A new method of finely temperature-tuning osmotic pressure allows one to identify the cholesteric --> line hexatic transition of oriented or unoriented long-fragment DNA bundles in monovalent salt solutions as first order, with a small but finite volume discontinuity. This transition is similar to the osmotic pressure-induced expanded --> condensed DNA transition in polyvalent salt solutions at small enough polyvalent salt concentrations. Therefore there exists a continuity of states between the two. This finding, together with the corresponding empirical equation of state, effectively relates the phase diagram of DNA solutions for monovalent salts to that for polyvalent salts and sheds some light on the complicated interactions between DNA molecules at high densities.
Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; Johnson, Mark R.; Parsegian, V. Adrian
2014-01-01
A new method of finely temperature-tuning osmotic pressure allows one to identify the cholesteric → line hexatic transition of oriented or unoriented long-fragment DNA bundles in monovalent salt solutions as first order, with a small but finite volume discontinuity. This transition is similar to the osmotic pressure-induced expanded → condensed DNA transition in polyvalent salt solutions at small enough polyvalent salt concentrations. Therefore there exists a continuity of states between the two. This finding, together with the corresponding empirical equation of state, effectively relates the phase diagram of DNA solutions for monovalent salts to that for polyvalent salts and sheds some light on the complicated interactions between DNA molecules at high densities. PMID:25371012
Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; Johnson, Mark R.; Parsegian, V. Adrian
2014-11-05
A new method of finely temperature-tuning osmotic pressure allows one to identify the cholesteric → line hexatic transition of oriented or unoriented long-fragment DNA bundles in monovalent salt solutions as first order, with a small but finite volume discontinuity. This transition is similar to the osmotic pressure-induced expanded → condensed DNA transition in polyvalent salt solutions at small enough polyvalent salt concentrations. Therefore there exists a continuity of states between the two. This finding with the corresponding empirical equation of state, effectively relates the phase diagram of DNA solutions for monovalent salts to that for polyvalent salts and sheds somemore » light on the complicated interactions between DNA molecules at high densities.« less
Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; Johnson, Mark R.; Parsegian, V. Adrian
2014-11-05
A new method of finely temperature-tuning osmotic pressure allows one to identify the cholesteric → line hexatic transition of oriented or unoriented long-fragment DNA bundles in monovalent salt solutions as first order, with a small but finite volume discontinuity. This transition is similar to the osmotic pressure-induced expanded → condensed DNA transition in polyvalent salt solutions at small enough polyvalent salt concentrations. Therefore there exists a continuity of states between the two. This finding with the corresponding empirical equation of state, effectively relates the phase diagram of DNA solutions for monovalent salts to that for polyvalent salts and sheds some light on the complicated interactions between DNA molecules at high densities.
Milyukova, M.S.; Varezhkina, N.S.; Kuzovkina, E.V.; Malikov, D.A.; Myasoedov, B.F.
1989-01-01
The behavior of trace amounts of americium(IV) in sulfuric and nitric acid solutions as a function of the mineral acid, potassium phosphotungstate, and ammonium persulfate concentrations was investigated. The stability of americium(IV) was studied. The optimal conditions and time of oxidation of trace amounts of americium to the tetravalent state were found on the basis of the experimental data obtained.
Technology Transfer Automated Retrieval System (TEKTRAN)
Detailed structural studies on the plant cell wall have traditionally been difficult. NMR is one of the preeminent structural tools, but obtaining high-resolution solution-state spectra has typically required fractionation and isolation of components of interest. With new methods for dissolution of,...
ERIC Educational Resources Information Center
Feldhausen, Thomas
As a partial solution to the energy crisis and to solve the problem of drastically rising operating costs coupled with less state support, in 1980-81 the Liberty School District (Spangle, Washington) implemented a 4-day school week comparable to the program used by Cimarron School District #3 in New Mexico. A survey conducted in 1975 by the…
Technology Transfer Automated Retrieval System (TEKTRAN)
A recently described plant cell wall dissolution system has been logically modified to utilize perdeuterated solvents to allow direct in-nmr-tube dissolution and high-resolution solution-state NMR of the whole cell wall without derivatization. Finely ground cell wall material dissolves in a solvent ...
NASA Technical Reports Server (NTRS)
Collier, G.
1967-01-01
Computer program VARI-QUIR 3 provides Gauss-Seidel type of solution with inner and outer iterations for steady-state, multigroup, two-dimensional neutron diffusion equations. The program has no restrictions on any of the input parameters such as the number of groups, regions, or materials.
NASA Astrophysics Data System (ADS)
Zech, Alraune; Attinger, Sabine
2016-05-01
A new method is presented which allows interpreting steady-state pumping tests in heterogeneous isotropic transmissivity fields. In contrast to mean uniform flow, pumping test drawdowns in heterogeneous media cannot be described by a single effective or equivalent value of hydraulic transmissivity. An effective description of transmissivity is required, being a function of the radial distance to the well and including the parameters of log-transmissivity: mean, variance, and correlation length. Such a model is provided by the upscaling procedure radial coarse graining, which describes the transition of near-well to far-field transmissivity effectively. Based on this approach, an analytical solution for a steady-state pumping test drawdown is deduced. The so-called effective well flow solution is derived for two cases: the ensemble mean of pumping tests and the drawdown within an individual heterogeneous transmissivity field. The analytical form of the solution allows inversely estimating the parameters of aquifer heterogeneity. For comparison with the effective well flow solution, virtual pumping tests are performed and analysed for both cases, the ensemble mean drawdown and pumping tests at individual transmissivity fields. Interpretation of ensemble mean drawdowns showed proof of the upscaling method. The effective well flow solution reproduces the drawdown for two-dimensional pumping tests in heterogeneous media in contrast to Thiem's solution for homogeneous media. Multiple pumping tests conducted at different locations within an individual transmissivity field are analysed, making use of the effective well flow solution to show that all statistical parameters of aquifer heterogeneity can be inferred under field conditions. Thus, the presented method is a promising tool with which to estimate parameters of aquifer heterogeneity, in particular variance and horizontal correlation length of log-transmissivity fields from steady-state pumping test measurements.
Method 101A (M101A) is similar to Method 101 for the determination of mercury (Hg) from stationary sources. n M101A, however, acidic potassium permanganate solution is used for sample collection instead of acidic iodine monochloride solution. his method applies to the determinati...
Homoclinic accretion solutions in the Schwarzschild-anti-de Sitter space-time
NASA Astrophysics Data System (ADS)
Mach, Patryk
2015-04-01
The aim of this paper is to clarify the distinction between homoclinic and standard (global) Bondi-type accretion solutions in the Schwarzschild-anti-de Sitter space-time. The homoclinic solutions have recently been discovered numerically for polytropic equations of state. Here I show that they exist also for certain isothermal (linear) equations of state, and an analytic solution of this type is obtained. It is argued that the existence of such solutions is generic, although for sufficiently relativistic matter models (photon gas, ultrahard equation of state) there exist global solutions that can be continued to infinity, similarly to standard Michel's solutions in the Schwarzschild space-time. In contrast to that global solutions should not exist for matter models with a nonvanishing rest-mass component, and this is demonstrated for polytropes. For homoclinic isothermal solutions I derive an upper bound on the mass of the black hole for which stationary transonic accretion is allowed.
Amine Gradient Stationary Phases on In-House Built Monolithic Columns for Liquid Chromatography.
Dewoolkar, Veeren C; Jeong, Lena N; Cook, Daniel W; Ashraf, Kayesh M; Rutan, Sarah C; Collinson, Maryanne M
2016-06-01
Stationary phase gradients on monolithic silica columns have been successfully and reproducibly prepared and characterized with comparisons made to uniformly modified stationary phases. Stationary phase gradients hold great potential for use in liquid chromatography (LC), both in terms of simplifying analysis as well as providing novel selectivity. In this work, we demonstrate the creation of a continuous stationary phase gradient on in-house synthesized monolithic columns by infusing an aminoalkoxysilane solution through the silica monoliths via controlled rate infusion. The presence of amine and its distribution along the length of gradient and uniformly modified columns were assessed via X-ray photoelectron spectroscopy (XPS). XPS showed a clear gradient in surface coverage along the length of the column for the gradient stationary phases while a near uniform distribution on the uniformly modified stationary phases. To demonstrate the application of these gradient stationary phases, the separations of both nucleobases and weak acids/weak bases on these gradient stationary phases have been compared to uniformly modified and unmodified silica columns. Of particular note, the retention characteristics of 11 gradient columns, 5 uniformly modified columns, and 5 unmodified columns have been tested to establish the reproducibility of the synthetic procedures. Standard deviations of the retention factors were in the range from 0.06 to 0.5, depending on the analyte species. We show that selectivity is achieved with the stationary phase gradients that are significantly different from either uniformly modified amine or unmodified columns. These results indicate the significant promise of this strategy for creating novel stationary phases for LC. PMID:27203513
Stationary Plasma Thruster Plume Characteristics
NASA Technical Reports Server (NTRS)
Myers, Roger M.; Manzella, David H.
1994-01-01
Stationary Plasma Thrusters (SPT's) are being investigated for application to a variety of near-term missions. This paper presents the results of a preliminary study of the thruster plume characteristics which are needed to assess spacecraft integration requirements. Langmuir probes, planar probes, Faraday cups, and a retarding potential analyzer were used to measure plume properties. For the design operating voltage of 300 V the centerline electron density was found to decrease from approximately 1.8 x 10 exp 17 cubic meters at a distance of 0.3 m to 1.8 X 10 exp 14 cubic meters at a distance of 4 m from the thruster. The electron temperature over the same region was between 1.7 and 3.5 eV. Ion current density measurements showed that the plume was sharply peaked, dropping by a factor of 2.6 within 22 degrees of centerline. The ion energy 4 m from the thruster and 15 degrees off-centerline was approximately 270 V. The thruster cathode flow rate and facility pressure were found to strongly affect the plume properties. In addition to the plume measurements, the data from the various probe types were used to assess the impact of probe design criteria
Ultrafast excited-state deactivation of 9-methylhypoxanthine in aqueous solution: A QM/MM MD study
NASA Astrophysics Data System (ADS)
Guo, Xugeng; Yuan, Huijuan; An, Beibei; Zhu, Qiuling; Zhang, Jinglai
2016-04-01
Photoinduced ultrafast non-adiabatic decay of 9-methylhypoxanthine (9MHPX) in aqueous solution was investigated by ab initio surface-hopping dynamics calculations using a combined quantum mechanical/molecular mechanical approach. The absorption spectra of 9MHPX in aqueous solution were also explored by the hybrid cluster-continuum model at the level of time-dependent density functional theory along with the polarizable continuum model (PCM). The static electronic-structure calculations indicate that the absorption spectra of 9MHPX simulated by TD-B3LYP/PCM and TD-X3LYP/PCM can reproduce very well the experimental findings, with the accuracy of about 0.20 eV. According to dynamics simulations, irradiation of 9MHPX populates the bright excited singlet S1 state, which may undergo an ultrafast non-radiative deactivation to the S0 state. The lifetime of the S1 state of 9MHPX in aqueous solution is predicted to be 115.6 fs, slightly longer than that in the gas phase (88.8 fs), suggesting that the solvent water has no significant influence on the excited-state lifetime of 9MHPX. Such a behavior in 9MHPX is distinctly different from its parent hypoxanthine keto-N9H tautomer in which the excited-state lifetime of the latter in water solution was remarkably enhanced as compared to the gas phase. The significant difference of the photodynamical behaviors between 9MHPX and keto-N9H can be ascribed to their different hydrogen bond environment in aqueous solution.
Federal Register 2010, 2011, 2012, 2013, 2014
2011-11-17
... Business Stationary Source Technical and Environmental Compliance Assistance Programs (SBTCP) Annual... this action are the State Small Business Stationary Source Technical and Environmental Compliance Assistance Programs (SBTCP). Title: State Small Business Stationary Source Technical and...
Jiang, Hao; Adidharma, Hertanto
2014-11-07
The thermodynamic modeling of flexible charged hard-sphere chains representing polyampholyte or polyelectrolyte molecules in solution is considered. The excess Helmholtz energy and osmotic coefficients of solutions containing short polyampholyte and the osmotic coefficients of solutions containing short polyelectrolytes are determined by performing canonical and isobaric-isothermal Monte Carlo simulations. A new equation of state based on the thermodynamic perturbation theory is also proposed for flexible charged hard-sphere chains. For the modeling of such chains, the use of solely the structure information of monomer fluid for calculating the chain contribution is found to be insufficient and more detailed structure information must therefore be considered. Two approaches, i.e., the dimer and dimer-monomer approaches, are explored to obtain the contribution of the chain formation to the Helmholtz energy. By comparing with the simulation results, the equation of state with either the dimer or dimer-monomer approach accurately predicts the excess Helmholtz energy and osmotic coefficients of polyampholyte and polyelectrolyte solutions except at very low density. It also well captures the effect of temperature on the thermodynamic properties of these solutions.
Yang, S.; Park, S.; Makowski, L.; Roux, B.
2009-02-01
Small angle X-ray scattering (SAXS) is an increasingly powerful technique to characterize the structure of biomolecules in solution. We present a computational method for accurately and efficiently computing the solution scattering curve from a protein with dynamical fluctuations. The method is built upon a coarse-grained (CG) representation of the protein. This CG approach takes advantage of the low-resolution character of solution scattering. It allows rapid determination of the scattering pattern from conformations extracted from CG simulations to obtain scattering characterization of the protein conformational landscapes. Important elements incorporated in the method include an effective residue-based structure factor for each amino acid, an explicit treatment of the hydration layer at the surface of the protein, and an ensemble average of scattering from all accessible conformations to account for macromolecular flexibility. The CG model is calibrated and illustrated to accurately reproduce the experimental scattering curve of Hen egg white lysozyme. We then illustrate the computational method by calculating the solution scattering pattern of several representative protein folds and multiple conformational states. The results suggest that solution scattering data, when combined with a reliable computational method, have great potential for a better structural description of multi-domain complexes in different functional states, and for recognizing structural folds when sequence similarity to a protein of known structure is low. Possible applications of the method are discussed.
NASA Astrophysics Data System (ADS)
Maheshwari, Chinmay
Cocrystals have drawn a lot of research interest in the last decade due to their potential to favorably alter the physicochemical and biopharmaceutical properties of active pharmaceutical ingredients. This dissertation focuses on the thermodynamic stability and solubility of pharmaceutical cocrystals. Specifically, the objectives are to; (i) investigate the influence of coformer properties such as solubility and ionization characteristics on cocrystal solubility and stability as a function of pH, (ii) to measure the thermodynamic solubility of metastable cocrystals, and study the solubility differences measured by kinetic and equilibrium methods, (iii) investigate the role of surfactants on the solubility and synthesis of cocrystals, (iv) investigate the solid state phase transformation of reactants to cocrystals and the factors that influence the reaction kinetics and, (v) provide models that enable the prediction of cocrystal formation by calculating the free energy of formation for a solid to solid transformation of reactants to cocrystals. Cocrystal solubilities were measured directly when cocrystals were thermodynamically stable, while solubilities were calculated from eutectic concentration measurements when cocrystals were of higher solubility than its components. Cocrystal solubility was highly dependent on coformer solubilities for gabapentin-lactam and lamotrigine cocrystals. It was found that melting point is not a good indicator of cocrystal solubility as solute-solvent interactions quantified by the activity coefficient play a huge role in the observed solubility. Similar to salts, cocrystals also exhibit pHmax, however the salts and cocrystals have different dependencies on the parameters that govern the value of pHmax. It is also shown that cocrystals could provide solubility advantage over salts as lamotrigine-nicotinamide cocrystal hydrate has about 6 fold higher solubility relative to lamotrigine-saccharin salt. In the case of mixtures of solid
Stationary solutions for metapopulation Moran models with mutation and selection.
Constable, George W A; McKane, Alan J
2015-03-01
We construct an individual-based metapopulation model of population genetics featuring migration, mutation, selection, and genetic drift. In the case of a single "island," the model reduces to the Moran model. Using the diffusion approximation and time-scale separation arguments, an effective one-variable description of the model is developed. The effective description bears similarities to the well-mixed Moran model with effective parameters that depend on the network structure and island sizes, and it is amenable to analysis. Predictions from the reduced theory match the results from stochastic simulations across a range of parameters. The nature of the fast-variable elimination technique we adopt is further studied by applying it to a linear system, where it provides a precise description of the slow dynamics in the limit of large time-scale separation. PMID:25871148
NASA Astrophysics Data System (ADS)
Sebastian, Indu; Divya, S.; Nampoori, V. P. N.; Radhakrishnan, P.; Thomas, Sheenu
2013-01-01
We present the linear and nonlinear optical studies on nanocolloidal solutions of Ga9Ge27Se64 glass with varying concentrations. Optical bandgap of the material is found to vary with respect to the concentration of the solute in the solution. An intermediate peak in the band tail of the absorption spectra is observed due to the presence of energy band in the forbidden gap. The existence of fluorescence emission confirms the above argument. Nonlinear absorption is studied using open aperture Z-scan technique. The mechanism behind nonlinear absorption is predicted as two photon as well as two step photon absorption. Nonlinearity increases with decrease in optical bandgap which in turn depends on the concentration of the nanocolloidal solutions.
NASA Astrophysics Data System (ADS)
Nie, Linfei; Peng, Jigen; Teng, Zhidong; Hu, Lin
2009-02-01
According to biological and chemical control strategy for pest, we investigate the dynamic behavior of a Lotka-Volterra predator-prey state-dependent impulsive system by releasing natural enemies and spraying pesticide at different thresholds. By using Poincaré map and the properties of the Lambert W function, we prove that the sufficient conditions for the existence and stability of semi-trivial solution and positive periodic solution. Numerical simulations are carried out to illustrate the feasibility of our main results.
Molecular structures and protonation state of 2-Mercaptopyridine in aqueous solution
NASA Astrophysics Data System (ADS)
Eckert, S.; Miedema, P. S.; Quevedo, W.; O'Cinneide, B.; Fondell, M.; Beye, M.; Pietzsch, A.; Ross, M.; Khalil, M.; Föhlisch, A.
2016-03-01
The speciation of 2-Mercaptopyridine in aqueous solution has been investigated with nitrogen 1s Near Edge X-ray Absorption Fine Structure spectroscopy and time dependent Density Functional Theory. The prevalence of distinct species as a function of the solvent basicity is established. No indications of dimerization towards high concentrations are found. The determination of different molecular structures of 2-Mercaptopyridine in aqueous solution is put into the context of proton-transfer in keto-enol and thione-thiol tautomerisms.
Genetics Home Reference: autosomal dominant congenital stationary night blindness
... stationary night blindness autosomal dominant congenital stationary night blindness Enable Javascript to view the expand/collapse boxes. ... Close All Description Autosomal dominant congenital stationary night blindness is a disorder of the retina , which is ...
A closed-form solution for steady-state coupled phloem/xylem flow using the Lambert-W function.
Hall, A J; Minchin, P E H
2013-12-01
A closed-form solution for steady-state coupled phloem/xylem flow is presented. This incorporates the basic Münch flow model of phloem transport, the cohesion model of xylem flow, and local variation in the xylem water potential and lateral water flow along the transport pathway. Use of the Lambert-W function allows this solution to be obtained under much more general and realistic conditions than has previously been possible. Variation in phloem resistance (i.e. viscosity) with solute concentration, and deviations from the Van't Hoff expression for osmotic potential are included. It is shown that the model predictions match those of the equilibrium solution of a numerical time-dependent model based upon the same mechanistic assumptions. The effect of xylem flow upon phloem flow can readily be calculated, which has not been possible in any previous analytical model. It is also shown how this new analytical solution can handle multiple sources and sinks within a complex architecture, and can describe competition between sinks. The model provides new insights into Münch flow by explicitly including interactions with xylem flow and water potential in the closed-form solution, and is expected to be useful as a component part of larger numerical models of entire plants. PMID:23617886
McEneaney, William M.
2004-08-15
Stochastic games under imperfect information are typically computationally intractable even in the discrete-time/discrete-state case considered here. We consider a problem where one player has perfect information.A function of a conditional probability distribution is proposed as an information state.In the problem form here, the payoff is only a function of the terminal state of the system,and the initial information state is either linear ora sum of max-plus delta functions.When the initial information state belongs to these classes, its propagation is finite-dimensional.The state feedback value function is also finite-dimensional,and obtained via dynamic programming,but has a nonstandard form due to the necessity of an expanded state variable.Under a saddle point assumption,Certainty Equivalence is obtained and the proposed function is indeed an information state.
An inversion-relaxation approach for sampling stationary points of spin model Hamiltonians
Hughes, Ciaran; Mehta, Dhagash; Wales, David J.
2014-05-21
Sampling the stationary points of a complicated potential energy landscape is a challenging problem. Here, we introduce a sampling method based on relaxation from stationary points of the highest index of the Hessian matrix. We illustrate how this approach can find all the stationary points for potentials or Hamiltonians bounded from above, which includes a large class of important spin models, and we show that it is far more efficient than previous methods. For potentials unbounded from above, the relaxation part of the method is still efficient in finding minima and transition states, which are usually the primary focus of attention for atomistic systems.
Entangled rings, matrix product states, and exact solutions of XYZ spin chains
Asoudeh, Marzieh; Karimipour, Vahid; Sadrolashrafi, Afsaneh
2007-07-15
We show that the ground state of the Heisenberg spin-1/2 chain in an external magnetic field, can be exactly expressed as a matrix product state, provided that the coupling constants are constrained to be on a specific two dimensional surface. This ground state has a very interesting property: all the pairs of spins are equally entangled with each other. In this last respect, the results are of interest for engineering long-range entanglement in experimentally realizable finite arrays of qubits, where the ground state will act as the initial state of a quantum computer.
Atenas, Boris; Pino, Luis A. del; Curilef, Sergio
2014-11-15
We study the classical behavior of an electric dipole in the presence of a uniform magnetic field. Using the Lagrangian formulation, we obtain the equations of motion, whose solutions are represented in terms of Jacobi functions. We also identify two constants of motion, namely, the energy E and a pseudomomentumC{sup →}. We obtain a relation between the constants that allows us to suggest the existence of a type of bound states without turning points, which are called trapped states. These results are consistent with and complementary to previous results. - Highlights: • Bound states without turning points. • Lagrangian Formulation for an electric dipole in a magnetic field. • Motion of the center of mass and trapped states. • Constants of motion: pseudomomentum and energy.
Inhomogeneity-induced bifurcation of stationary and oscillatory pulses
NASA Astrophysics Data System (ADS)
Prat, Alain; Li, Yue-Xian; Bressloff, Paul
2005-03-01
An excitable medium generally refers to a medium that is capable of generating traveling waves. It has been widely encountered in biology, chemistry and physics. Many excitable media have been modeled by systems of PDEs of the reaction-diffusion type. Excitable neural media are often modeled by integro-differential equations (IDEs). In both PDE and IDE models of excitable media, stationary spatial patterns of Turing’s type can occur under certain conditions. Such patterns have been used to explain a variety of biological pattern formation processes including morphogenesis and hallucination. Here we study a pattern formation mechanism that is different from Turing’s, called inhomogeneity-induced pattern formation. Such patterns can occur in an excitable medium either with an inhomogeneous but stationary forcing or a spatial variation in a model parameter. The interesting thing we found is: introducing a stationary bump into such a medium does not always produce just a simple bump-shaped output pattern. A complex bifurcation scenario can occur giving rise to the co-existence of multiple patterns. A stability analysis shows that the instability of such patterns often occurs through a Hopf bifurcation, giving rise to oscillatory pulse solutions. Such oscillatory pulses can behave like a pulse generator that emits traveling pulses periodically into the medium. Possible areas in biology where this theory can be applied will be discussed.
Jiang, Qiong; Zhang, Mingliang; Wang, Xusheng; Guo, Yong; Qiu, Hongdeng; Zhang, Shusheng
2015-10-01
A glucaminium-based ionic liquid stationary phase was prepared via facile epoxy-amine reaction and subsequent quaternization. Successful immobilization of glucaminium-based ionic liquid onto silica surface was validated by elemental analysis and infrared spectroscopy. The new stationary phase was evaluated for the separation of nucleosides in hydrophilic interaction liquid chromatography (HILIC). Effects of various factors, such as acetonitrile concentration, salt concentration, pH value, as well as column temperature, on the chromatographic behavior toward nucleosides were studied in detail. The results indicated that this new stationary phase can be used for separation of water-soluble polar substances in HILIC mode. The retention of solutes on the stationary phase was influenced by a mixed-mode retention mechanism with a combination of adsorptive and partitioning interactions. PMID:26231689
NASA Technical Reports Server (NTRS)
1985-01-01
Most microscopic cell electrophoretic work depends on the theortical prediction of stationary positions by Smoluchowski and Komagata. Their theoretical solutions are based on the assumption that the electroosmotic flow in a chamber is symmetric. Because experiences with the rectangular chamber indicate that symmetric flow occurs during less than 8% of the experiments, the existing theory for stationary position determination is expanded to include the more general case of asymmetric flow. Smoluchowski's equation for symmetric electroosmotic flow in a rectangular chamber having a width much smaller than its height or length is examined. Smoluchowski's approach is used to approximate stationary positions in rectangular chambers with height/width ratios greater than 40. Support for the theoretical prediction of stationary positions using is given by three types of experimental evidence.
INSTRUMENTAL SENSING OF STATIONARY SOURCE EMISSIONS
Remote sensing methods offer a number of advantages over contact measurement methods in the area of enforcement and surveillance of emissions from stationary sources. Several techniques have been developed that can measure the gas concentration, effluent velocity, and particulate...
Implementing stationary-phase optimized selectivity in supercritical fluid chromatography.
Delahaye, Sander; Lynen, Frédéric
2014-12-16
The performance of stationary-phase optimized selectivity liquid chromatography (SOS-LC) for improved separation of complex mixtures has been demonstrated before. A dedicated kit containing column segments of different lengths and packed with different stationary phases is commercially available together with algorithms capable of predicting and ranking isocratic and gradient separations over vast amounts of possible column combinations. Implementation in chromatographic separations involving compressible fluids, as is the case in supercritical fluid chromatography, had thus far not been attempted. The challenge of this approach is the dependency of solute retention with the mobile-phase density, complicating linear extrapolation of retention over longer or shorter columns segments, as is the case in conventional SOS-LC. In this study, the possibilities of performing stationary-phase optimized selectivity supercritical fluid chromatography (SOS-SFC) are demonstrated with typical low density mobile phases (94% CO2). The procedure is optimized with the commercially available column kit and with the classical isocratic SOS-LC algorithm. SOS-SFC appears possible without any density correction, although optimal correspondence between prediction and experiment is obtained when isopycnic conditions are maintained. As also the influence of the segment order appears significantly less relevant than expected, the use of the approach in SFC appears as promising as is the case in HPLC. Next to the classical use of SOS for faster baseline separation of all solutes in a mixture, the benefits of the approach for predicting as wide as possible separation windows around to-be-purified solutes in semipreparative SFC are illustrated, leading to significant production rate improvements in (semi)preparative SFC. PMID:25393519
Dampers for Stationary Labyrinth Seals
NASA Technical Reports Server (NTRS)
El-Aini, Yehia; Mitchell, William; Roberts, Lawrence; Montgomery, Stuart; Davis, Gary
2011-01-01
Vibration dampers have been invented that are incorporated as components within the stationary labyrinth seal assembly. These dampers are intended to supplement other vibration-suppressing features of labyrinth seals in order to reduce the incidence of high-cycle-fatigue failures, which have been known to occur in the severe vibratory environments of jet engines and turbopumps in which labyrinth seals are typically used. A vibration damper of this type includes several leaf springs and/or a number of metallic particles (shot) all held in an annular seal cavity by a retaining ring. The leaf springs are made of a spring steel alloy chosen, in conjunction with design parameters, to maintain sufficient preload to ensure effectiveness of damping at desired operating temperatures. The cavity is vented via a small radial gap between the retaining ring and seal housing. The damping mechanism is complex. In the case of leaf springs, the mechanism is mainly friction in the slippage between the seal housing and individual dampers. In the case of a damper that contains shot, the damping mechanism includes contributions from friction between individual particles, friction between particles and cavity walls, and dissipation of kinetic energy of impact. The basic concept of particle/shot vibration dampers has been published previously; what is new here is the use of such dampers to suppress traveling-wave vibrations in labyrinth seals. Damping effectiveness depends on many parameters, including, but not limited to, coefficient of friction, mode shape, and frequency and amplitude of vibrational modes. In tests, preloads of the order of 6 to 15 lb (2.72 to 6.8 kilograms) per spring damper were demonstrated to provide adequate damping levels. Effectiveness of shot damping of vibrations having amplitudes from 20 to 200 times normal terrestrial gravitational acceleration (196 to 1,960 meters per square second) and frequencies up to 12 kHz was demonstrated for shot sizes from 0.032 to
NASA Astrophysics Data System (ADS)
El Assaid, M.; El Aydi, M'hamed; El Feddi, M.; Dujardin, Françis
2008-03-01
The problem of a shallow donor impurity located at the centre of a symmetrical paraboloidal quantum dot (SPQD) is solved exactly. The Schrödinger equation is separated in the paraboloidal coordinate system. Three different cases are discussed for the radial-like equations. For a bound donor, the energy is negative and the solutions are described by Whittaker functions. For a non-bound donor, the energy is positive and the solutions become coulomb wave functions. In the last case, the energy is equal to zero and the solutions reduce to Bessel functions. Using the boundary conditions at the dot surfaces, the variations of the donor kinetic and potential energies versus the size of the dot are obtained. The problem of a shallow donor impurity in a Hemiparaboloidal Quantum dot (HPQD) is also studied. It is shown that the wave functions of a HPQD are specific linear combinations of those of a SPQD.
A Raman Study of Alcoholic Lithium Perchlorate Solutions in the Glassy State
NASA Astrophysics Data System (ADS)
Kanno, H.; Honshoh, M.; Yamauchi, S.
1995-03-01
Raman spectra of alcoholic lithium Perchlorate solutions (alcohol = methanol and ethanol) were measured as a function of LiClO4 concentration. The Raman band due to nearly free hydrogen bonds shows peculiar concentration dependences: (1) its frequency shifts with LiClO4 concentration in contrast to alcoholic LiX solutions (X = CI and Br), in which the Raman band due to solvated halide ions shows little frequency change with LiX concentration, and (2) the half band width shows anomalous changes with LiX concentration. Non-ionized LiClO4 species in alcohol coupled with the changes of solution structure are the major cause for this peculiar behavior.
Stationary phase deposition based on onium salts
Wheeler, David R.; Lewis, Patrick R.; Dirk, Shawn M.; Trudell, Daniel E.
2008-01-01
Onium salt chemistry can be used to deposit very uniform thickness stationary phases on the wall of a gas chromatography column. In particular, the stationary phase can be bonded to non-silicon based columns, especially microfabricated metal columns. Non-silicon microfabricated columns may be manufactured and processed at a fraction of the cost of silicon-based columns. In addition, the method can be used to phase-coat conventional capillary columns or silicon-based microfabricated columns.
Lim, Kwang Hun; Dasari, Anvesh K R; Hung, Ivan; Gan, Zhehong; Kelly, Jeffery W; Wemmer, David E
2016-04-01
Elucidation of structural changes involved in protein misfolding and amyloid formation is crucial for unraveling the molecular basis of amyloid formation. Here we report structural analyses of the amyloidogenic intermediate and amyloid aggregates of transthyretin using solution and solid-state nuclear magnetic resonance (NMR) spectroscopy. Our solution NMR results show that one of the two main β-sheet structures (CBEF β-sheet) is maintained in the aggregation-competent intermediate, while the other DAGH β-sheet is more flexible on millisecond time scales. Magic-angle-spinning solid-state NMR revealed that AB loop regions interacting with strand A in the DAGH β-sheet undergo conformational changes, leading to the destabilized DAGH β-sheet. PMID:26998642
Mulfort, K. L.; Tiede, D. M.
2010-01-01
In this report, we have investigated the correlations between structure and light-induced electron transfer of one known and three new axially coordinated cobaloxime-based supramolecular photocatalysts for the reduction of protons to hydrogen. Solution-phase X-ray scattering and ultrafast transient optical spectroscopy analyses were used in tandem to correlate the self-assembled photocatalysts structural integrity in solution with electron transfer and charge separation between the photosensitizer and catalyst fragments. Biphasic excited state decay kinetics were observed for several of the assemblies, suggesting that configurational dispersion plays a role in limiting photoinduced electron transfer. Notably, an assembly featuring a 'push-pull' donor-photosensitizer-acceptor triad motif exhibits considerable ultrafast excited state quenching and, of the assemblies examined, presents the strongest opportunity for efficient solar energy conversion. These results will assist in the design and development of next-generation supramolecular photocatalyst architectures.
A Comparative Study of Stationary and Non-stationary Wind Models Using Field Measurements
NASA Astrophysics Data System (ADS)
Chen, Jun; Hui, Michael C. H.; Xu, Y. L.
2007-01-01
We present a comparative study of the conventional stationary wind speed model and a newly proposed non-stationary wind speed model using field measurements. The concept of, and the differences between, the two wind models are briefly reviewed. Wind data recorded by a field measurement system for wind turbulence parameters (FMS-WTP) of 1-year duration are analyzed using the two wind models. Comparisons were made between the wind characteristics obtained from the two models, including hourly mean wind speed, turbulence intensity, the wind spectrum, integral length scale, root coherence function and probability density function. The effects of wind types (monsoon or typhoon), statistical properties (stationary or non-stationary), and surface roughness (open-sea fetch or overland fetch) on wind characteristics are discussed. The comparative study demonstrates that the non-stationary wind model appears to be more appropriate than the conventional stationary wind speed model for characterizing turbulent winds of one-hour duration over complex terrain.
NASA Astrophysics Data System (ADS)
Tanaka, Yasuhiko; Hirayama, Kohei; Niidome, Yasuro; Nakashima, Naotoshi
2009-11-01
Solution redox chemistry is useful to understand the chirality-dependent electronic properties of single-walled carbon nanotubes (SWNTs). We have found that the electron transfer reactions of sodium dithionite with SWNTs cause photoluminescence (PL) quenching processes of 14 individually dissolved SWNTs in an aqueous micellar solution. Based on the analysis using the Nernst equation for the PL change, we have determined the conduction band ( c1) levels of the 14 isolated SWNTs. We have also estimated the valence band ( ν1) levels as well as the Fermi levels of the SWNTs using the reported bandgap values of the corresponding isolated SWNTs.
NASA Astrophysics Data System (ADS)
Venâncio, Mateus F.; Rocha, Willian R.
2015-10-01
Ab initio molecular dynamics simulations were used to investigate the early chemical events involved in the dynamics of nitric oxide (NOrad), nitrosonium cation (NO+) and nitroxide anion (NO-) in aqueous solution. The NO+ ion is very reactive in aqueous solution having a lifetime of ∼4 × 10-13 s, which is shorter than the value of 3 × 10-10 s predicted experimentally. The NO+ reacts generating the nitrous acid as an intermediate and the NO2- ion as the final product. The dynamics of NOrad revealed the reversibly formation of a transient anion radical species HONOrad -.
Mondal, Satyajit; Ghosh, Soumen; Moulik, Satya P
2016-05-01
In aqueous solution, curcumin is photodegradable (light sensitive), it is also self-degradable in the dark. In basic medium, the second process is enhanced. The dark process has been studied in water and also in a number of protic and aprotic solvents, and aqueous solutions of ionic liquids, pluronics, reverse micelles and salt. The kinetics of the process followed the first order rate law; a comparative as well as individual assessment of which has been made. The kinetics of curcumin self-degradation has been found to be fairly dependent on salt (NaCl) concentration. Curcumin molecules in solution may remain in the enol or keto-enol form. From the visible spectral analysis, an estimate of the proportions of these forms in aqueous ethanol medium has been made. The temperature effect on the visible and fluorescence spectra of curcumin has been also studied. The steady state fluorescence anisotropy of the photoactive curcumin has been evaluated in different solvent and solution media. The reversibility of the steady state fluorescence anisotropy of curcumin on heating and cooling conditions has been examined. The results herein presented are new and ought to be useful as the study of physicochemistry of curcumin has been gaining importance in the light of its biological importance. PMID:26985735
Garabedian, Stephen P
2013-01-01
A new steady-state analytical solution to the two-dimensional radial-flow equation was developed for drawdown (head) conditions in an aquifer with constant transmissivity, no-flow conditions at the top and bottom, constant head conditions at a known radial distance, and a partially completed pumping well. The solution was evaluated for accuracy by comparison to numerical simulations using MODFLOW. The solution was then used to estimate the rise of the salt water-fresh water interface (upconing) that occurs under a pumping well, and to calculate the critical pumping rate at which the interface becomes unstable, allowing salt water to enter the pumping well. The analysis of salt water-fresh water interface rise assumed no significant effect on upconing by recharge; this assumption was tested and supported using results from a new steady-state analytical solution developed for recharge under two-dimensional radial-flow conditions. The upconing analysis results were evaluated for accuracy by comparison to those from numerical simulations using SEAWAT for salt water-fresh water interface positions under mild pumping conditions. The results from the equation were also compared with those of a published numerical sharp-interface model applied to a case on Cape Cod, Massachusetts. This comparison indicates that estimating the interface rise and maximum allowable pumping rate using the analytical method will likely be less conservative than the maximum allowable pumping rate and maximum stable interface rise from a numerical sharp-interface model. PMID:23336341
Gravitational and mass distribution effects on stationary superwinds.
NASA Astrophysics Data System (ADS)
Añorve-Zeferino, G. A.
2016-08-01
Here, we model the effect of non-uniform dynamical mass distributions and their associated gravitational fields on the stationary galactic superwind solution. We do this by considering an analogue injection of mass and energy from stellar winds and SNe. We consider both compact dark-matter and baryonic haloes that does not extend further from the galaxies optical radii Ropt as well as extended gravitationally-interacting ones. We consider halo profiles that emulate the results of recent cosmological simulations and coincide also with observational estimations from galaxy surveys. This allows to compare the analytical superwind solution with outflows from different kinds of galaxies. We give analytical formulae that establish when an outflow is possible and also characterize distinct flow regimes and enrichment scenarios. We also constraint the parameter space by giving approximate limits above which gravitation, self-gravitation and radiative cooling can inhibit the stationary flow. We obtain analytical expressions for the free superwind hydrodynamical profiles. We find that the existence or inhibition of the superwind solution highly depends on the steepness and concentration of the dynamical mass and the mass and energy injection rates. We compare our results with observational data and a recent numerical work. We put our results in the context of the mass-metallicity relationship to discuss observational evidence related to the selective loss of metals from the least massive galaxies and also discuss the case of massive galaxies.
Parallel state-space search for a first solution with consistent linear speedups
Kale, L.V.; Saletore, V.A. )
1989-01-01
Consider the problem of exploring a large state-space for a goal state. Although many such states may exist in the state-space, finding any one state satisfying the requirements is sufficient. All the methods known until now for conducting such search in parallel using multiprocessors fail to provide consistent linear speedups over sequential execution. The speedups vary between sub-linear speedups over sequential execution. The speedup, giving rise to speedup anomalies reported in literature. The authors present a prioritizing strategy which yields consistent speedups that are close to P with P processors, and that monotonically increase with the addition of processors. It achieves this by keeping the total number of nodes expanded during parallel search very close to that in a sequential search. In addition, the strategy requires substantially smaller memory over other methods. The performance of this strategy is demonstrated on a multiprocessor with several state-space search problems.
NASA Technical Reports Server (NTRS)
Gartling, D. K.; Roache, P. J.
1978-01-01
The efficiency characteristics of finite element and finite difference approximations for the steady-state solution of the Navier-Stokes equations are examined. The finite element method discussed is a standard Galerkin formulation of the incompressible, steady-state Navier-Stokes equations. The finite difference formulation uses simple centered differences that are O(delta x-squared). Operation counts indicate that a rapidly converging Newton-Raphson-Kantorovitch iteration scheme is generally preferable over a Picard method. A split NOS Picard iterative algorithm for the finite difference method was most efficient.
Dissipative double-well potential: Nonlinear stationary and pulsating modes
Zezyulin, Dmitry A.; Konotop, Vladimir V.; Alfimov, Georgy L.
2010-11-15
The analysis of nonlinear modes in a complex absorbing double-well potential supported by linear gain is presented. Families of the nonlinear modes and their bifurcations are found numerically by means of the properly modified 'shooting' method. Linear stability and dynamics of the modes are studied. It is shown that no stable modes exist in the case of attractive nonlinearity, while stable modes, including nonsymmetric ones, are found when the nonlinearity is repulsive. Varying a control parameter (e.g., the height of barrier between the wells) results in switching from one mode to another. Apart from stationary modes we have found pulsating solutions emergent from unstable modes.
Stationary Liquid Fuel Fast Reactor
Yang, Won Sik; Grandy, Andrew; Boroski, Andrew; Krajtl, Lubomir; Johnson, Terry
2015-09-30
For effective burning of hazardous transuranic (TRU) elements of used nuclear fuel, a transformational advanced reactor concept named SLFFR (Stationary Liquid Fuel Fast Reactor) was proposed based on stationary molten metallic fuel. The fuel enters the reactor vessel in a solid form, and then it is heated to molten temperature in a small melting heater. The fuel is contained within a closed, thick container with penetrating coolant channels, and thus it is not mixed with coolant nor flow through the primary heat transfer circuit. The makeup fuel is semi- continuously added to the system, and thus a very small excess reactivity is required. Gaseous fission products are also removed continuously, and a fraction of the fuel is periodically drawn off from the fuel container to a processing facility where non-gaseous mixed fission products and other impurities are removed and then the cleaned fuel is recycled into the fuel container. A reference core design and a preliminary plant system design of a 1000 MWt TRU- burning SLFFR concept were developed using TRU-Ce-Co fuel, Ta-10W fuel container, and sodium coolant. Conservative design approaches were adopted to stay within the current material performance database. Detailed neutronics and thermal-fluidic analyses were performed to develop a reference core design. Region-dependent 33-group cross sections were generated based on the ENDF/B-VII.0 data using the MC2-3 code. Core and fuel cycle analyses were performed in theta-r-z geometries using the DIF3D and REBUS-3 codes. Reactivity coefficients and kinetics parameters were calculated using the VARI3D perturbation theory code. Thermo-fluidic analyses were performed using the ANSYS FLUENT computational fluid dynamics (CFD) code. Figure 0.1 shows a schematic radial layout of the reference 1000 MWt SLFFR core, and Table 0.1 summarizes the main design parameters of SLFFR-1000 loop plant. The fuel container is a 2.5 cm thick cylinder with an inner radius of 87.5 cm. The fuel
NASA Astrophysics Data System (ADS)
He, Xiaolong; de la Llave, Rafael
2016-08-01
We construct analytic quasi-periodic solutions of a state-dependent delay differential equation with quasi-periodically forcing. We show that if we consider a family of problems that depends on one dimensional parameters (with some non-degeneracy conditions), there is a positive measure set Π of parameters for which the system admits analytic quasi-periodic solutions. The main difficulty to be overcome is the appearance of small divisors and this is the reason why we need to exclude parameters. Our main result is proved by a Nash-Moser fast convergent method and is formulated in the a-posteriori format of numerical analysis. That is, given an approximate solution of a functional equation which satisfies some non-degeneracy conditions, we can find a true solution close to it. This is in sharp contrast with the finite regularity theory developed in [18]. We conjecture that the exclusion of parameters is a real phenomenon and not a technical difficulty. More precisely, for generic families of perturbations, the quasi-periodic solutions are only finitely differentiable in open sets in the complement of parameters set Π.
Effect of phase noise on the generation of stationary entanglement in cavity optomechanics
Abdi, M.; Barzanjeh, Sh.; Tombesi, P.; Vitali, D.
2011-09-15
We study the effect of laser phase noise on the generation of stationary entanglement between an intracavity optical mode and a mechanical resonator in a generic cavity optomechanical system. We show that one can realize robust stationary optomechanical entanglement even in the presence of non-negligible laser phase noise. We also show that the explicit form of the laser phase noise spectrum is relevant, and discuss its effect on both optomechanical entanglement and ground-state cooling of the mechanical resonator.
Tsai, Ming Kang; Kowalski, Karol; Valiev, Marat; Dupuis, Michel
2007-10-25
ab initio electronic structure theories applied to cluster models support the characterization of the signature of the OH absorption spectrum to be a solvent-to-solute charge transfer state affected by the hydrogen bonding environment in the region of 250 nm (calculated). The vertical excited states were calculated at the TDDFT level of theory with using OH(H2O)n clusters (n = 0-7, 16) with companion calculations at the EOM-CCSD level of theory for n ≤ 7. An intense solvent-to-solute charge transfer transition was calculated for n = 16 cluster where the donor and acceptor molecular orbitals are in favorable alignment. In the other smaller clusters the transitions in this region were found to be weak. The present findings are consistent with the experimental absorption at 230 nm suggested to be a solvent-to-solute charge transfer and provide insight into the electronic states and orbitals that give rise to the intensity of the band. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program, and was performed in part using the Molecular Science Computing Facility (MSCF) in the William R. Wiley Environmental Molecular Sciences Laboratory, a DOE national scientific user facility located at the Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for DOE.
NASA Astrophysics Data System (ADS)
Rai, R. N.; Kant, Shiva; Reddi, R. S. B.; Ganesamoorthy, S.; Gupta, P. K.
2016-01-01
Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal.
Summary of States' Strategies and Consequences for ESEA Focus Schools. Solutions. Issue No. 2
ERIC Educational Resources Information Center
Perlman, Carole
2013-01-01
As of January 1, 2013, 34 states and the District of Columbia have been granted waivers from certain provisions of the Elementary and Secondary Education Act (ESEA). Part of each successful flexibility application was a state accountability system that could identify priority schools (the lowest performing 5% of Title 1 schools) and focus schools…
Summary of States' Strategies and Consequences for ESEA Focus Schools. Solutions. Issue Number 2
ERIC Educational Resources Information Center
Perlman, Carole
2013-01-01
As of January 1, 2013, 34 states and the District of Columbia have been granted waivers from certain provisions of the Elementary and Secondary Education Act (ESEA). Part of each successful flexibility application was a state accountability system that could identify priority schools (the lowest performing 5% of Title 1 schools) and focus schools…
Summary of States' Strategies for ESEA Priority Schools. Solutions. Issue No. 6
ERIC Educational Resources Information Center
Perlman, Carole
2013-01-01
By the end of 2013, 42 states and the District of Columbia have been granted flexibility regarding specific requirements of the No Child Left Behind Act of 2001 (NCLB) in exchange for rigorous and comprehensive state-developed plans designed to improve educational outcomes for all students, close achievement gaps, increase equity, and improve the…
Buckingham, A.C.; Siekhaus, W.J.
1982-09-27
The unsteady, non-similar, chemically reactive, turbulent boundary layer equations are modified for gas plus dispersed solid particle mixtures, for gas phase turbulent combustion reactions and for heterogeneous gas-solid surface erosive reactions. The exterior (ballistic core) edge boundary conditions for the solutions are modified to include dispersed particle influences on core propellant combustion-generated turbulence levels, combustion reactants and products, and reaction-induced, non-isentropic mixture states. The wall surface (in this study it is always steel) is considered either bare or coated with a fixed particle coating which is conceptually non-reactive, insulative, and non-ablative. Two families of solutions are compared. These correspond to: (1) consideration of gas-borne, free-slip, almost spontaneously mobile (motile) solid particle additives which influence the turbulent heat transfer at the uncoated steel surface and, in contrast, (2) consideration of particle-free, gas phase turbulent heat transfer to the insulated surface coated by stationary particles. Significant differences in erosive heat transfer are found in comparing the two families of solutions over a substantial range of interior ballistic flow conditions. The most effective influences on reducing erosive heat transfer appear to favor mobile, gas-borne particle additives.
Efficient solution of liquid state integral equations using the Newton-GMRES algorithm
NASA Astrophysics Data System (ADS)
Booth, Michael J.; Schlijper, A. G.; Scales, L. E.; Haymet, A. D. J.
1999-06-01
We present examples of the accurate, robust and efficient solution of Ornstein-Zernike type integral equations which describe the structure of both homogeneous and inhomogeneous fluids. In this work we use the Newton-GMRES algorithm as implemented in the public-domain nonlinear Krylov solvers NKSOL [ P. Brown, Y. Saad, SIAM J. Sci. Stat. Comput. 11 (1990) 450] and NITSOL [ M. Pernice, H.F. Walker, SIAM J. Sci. Comput. 19 (1998) 302]. We compare and contrast this method with more traditional approaches in the literature, using Picard iteration (successive-substitution) and hybrid Newton-Raphson and Picard methods, and a recent vector extrapolation method [ H.H.H. Homeier, S. Rast, H. Krienke, Comput. Phys. Commun. 92 (1995) 188]. We find that both the performance and ease of implementation of these nonlinear solvers recommend them for the solution of this class of problem.
NASA Astrophysics Data System (ADS)
Colaiori, Francesca; Castellano, Claudio; Cuskley, Christine F.; Loreto, Vittorio; Pugliese, Martina; Tria, Francesca
2015-01-01
Empirical evidence shows that the rate of irregular usage of English verbs exhibits discontinuity as a function of their frequency: the most frequent verbs tend to be totally irregular. We aim to qualitatively understand the origin of this feature by studying simple agent-based models of language dynamics, where each agent adopts an inflectional state for a verb and may change it upon interaction with other agents. At the same time, agents are replaced at some rate by new agents adopting the regular form. In models with only two inflectional states (regular and irregular), we observe that either all verbs regularize irrespective of their frequency, or a continuous transition occurs between a low-frequency state, where the lemma becomes fully regular, and a high-frequency one, where both forms coexist. Introducing a third (mixed) state, wherein agents may use either form, we find that a third, qualitatively different behavior may emerge, namely, a discontinuous transition in frequency. We introduce and solve analytically a very general class of three-state models that allows us to fully understand these behaviors in a unified framework. Realistic sets of interaction rules, including the well-known naming game (NG) model, result in a discontinuous transition, in agreement with recent empirical findings. We also point out that the distinction between speaker and hearer in the interaction has no effect on the collective behavior. The results for the general three-state model, although discussed in terms of language dynamics, are widely applicable.
Winkel, K; Seidl, M; Loerting, T; Bove, L E; Imberti, S; Molinero, V; Bruni, F; Mancinelli, R; Ricci, M A
2011-01-14
Neutron diffraction experiments on a solution of LiCl in water (R = 40) at ambient conditions and in the supercooled and hyperquenched states are reported and analyzed within the empirical potential structure refinement framework. Evidence for the modifications of the microscopic structure of the solvent in the presence of such a small amount of salt is found at all investigated thermodynamic states. On the other hand, it is evident that the structure of the hyperquenched salty sample is similar to that of pure low density amorphous water, although all the peaks of the radial distribution functions are broader in the present case. Changes upon supercooling or hyperquenching of the ion's hydration shells and contacts are of limited size and evidence for segregation phenomena at these states does not clearly show up, although the presence of water separated contacts between ion of the same sign is intriguing. PMID:21241128
NASA Astrophysics Data System (ADS)
Wang, Shuoqin; Verbrugge, Mark; Wang, John S.; Liu, Ping
2011-10-01
We report the development of an adaptive, multi-parameter battery state estimator based on the direct solution of the differential equations that govern an equivalent circuit representation of the battery. The core of the estimator includes two sets of inter-related equations corresponding to discharge and charge events respectively. Simulation results indicate that the estimator gives accurate prediction and numerically stable performance in the regression of model parameters. The estimator is implemented in a vehicle-simulated environment to predict the state of charge (SOC) and the charge and discharge power capabilities (state of power, SOP) of a lithium ion battery. Predictions for the SOC and SOP agree well with experimental measurements, demonstrating the estimator's application in battery management systems. In particular, this new approach appears to be very stable for high-frequency data streams.
Stationary axisymmetric and slowly rotating spacetimes in Hořava-Lifshitz gravity.
Wang, Anzhong
2013-03-01
Stationary, axisymmetric, and slowly rotating vacuum spacetimes in the Hořava-Lifshitz (HL) gravity are studied, and it is shown that, for any given spherical static vacuum solution of the HL theory (of any model, including the ones with an additional U(1) symmetry), there always exists a corresponding slowly rotating, stationary, and axisymmetric vacuum solution, which reduces to the former, when the rotation is switched off. The rotation is universal and only implicitly depends on the models of the HL theory and their coupling constants through the spherical seed solution. As a result, all asymptotically flat slowly rotating vacuum solutions are asymptotically identical to the slowly rotating Kerr solution. This is in contrast to the claim of Barausse and Sotiriou [Phys. Rev. Lett. 109, 181101 (2012)], in which slowly rotating black holes were reported (incorrectly) not to exist in the infrared limit of the nonprojectable HL theory. PMID:23496699
Evolutionary cheating in Escherichia coli stationary phase cultures.
Vulic, M; Kolter, R
2001-01-01
Starved cultures of Escherichia coli are highly dynamic, undergoing frequent population shifts. The shifts result from the spread of mutants able to grow under conditions that impose growth arrest on the ancestral population. To analyze competitive interactions underlying this dynamic we measured the survival of a typical mutant and the wild type during such population shifts. Here we show that the survival advantage of the mutant at any given time during a takeover is inversely dependent on its frequency in the population, its growth adversely affects the survival of the wild type, and its ability to survive in stationary phase at fixation is lower than that of its ancestor. These mutants do not enter, or exit early, the nondividing stationary-phase state, cooperatively maintained by the wild type. Thus they end up overrepresented as compared to their initial frequency at the onset of the stationary phase, and subsequently they increase disproportionately their contribution in terms of progeny to the succeeding generation in the next growth cycle, which is a case of evolutionary cheating. If analyzed through the game theory framework, these results might be explained by the prisoner's dilemma type of conflict, which predicts that selfish defection is favored over cooperation. PMID:11404318
On the `Stationary Implies Axisymmetric' Theorem for Extremal Black Holes in Higher Dimensions
NASA Astrophysics Data System (ADS)
Hollands, Stefan; Ishibashi, Akihiro
2009-10-01
All known stationary black hole solutions in higher dimensions possess additional rotational symmetries in addition to the stationary Killing field. Also, for all known stationary solutions, the event horizon is a Killing horizon, and the surface gravity is constant. In the case of non-degenerate horizons (non-extremal black holes), a general theorem was previously established [24] proving that these statements are in fact generally true under the assumption that the spacetime is analytic, and that the metric satisfies Einstein’s equation. Here, we extend the analysis to the case of degenerate (extremal) black holes. It is shown that the theorem still holds true if the vector of angular velocities of the horizon satisfies a certain “diophantine condition,” which holds except for a set of measure zero.
NASA Astrophysics Data System (ADS)
Terayama, Y.; Arita, H.; Ishikawa, T.; Kikuchi, M.; Mitamura, K.; Kobayashi, M.; Yamada, N. L.; Takahara, A.
2011-01-01
The chain dimensions of free and immobilized polysulfobetaine in aqueous solution at various salt concentrations were investigated by size-exclusion chromatography with multiangle light scattering and neutron reflectivity measurement, respectively. The dependence of the z-average mean square radius of gyration (
Emani, Prashant S; Olsen, Gregory L; Echodu, Dorothy C; Varani, Gabriele; Drobny, Gary P
2010-12-01
Functional RNA molecules are conformationally dynamic and sample a multitude of dynamic modes over a wide range of frequencies. Thus, a comprehensive description of RNA dynamics requires the inclusion of a broad range of motions across multiple dynamic rates which must be derived from multiple spectroscopies. Here we describe a slow conformational exchange theoretical approach to combining the description of local motions in RNA that occur in the nanosecond to microsecond window and are detected by solid-state NMR with nonrigid rotational motion of the HIV-1 transactivation response element (TAR) RNA in solution as observed by solution NMR. This theoretical model unifies the experimental results generated by solution and solid-state NMR and provides a comprehensive view of the dynamics of HIV-1 TAR RNA, a well-known paradigm of an RNA where function requires extensive conformational rearrangements. This methodology provides a quantitative atomic level view of the amplitudes and rates of the local and collective displacements of the TAR RNA molecule and provides directly motional parameters for the conformational capture hypothesis of this classical RNA-ligand interaction. PMID:21067190
Hooper, R.P.; Peters, N.E.
1989-01-01
A principal-components analysis was performed on the major solutes in wet deposition collected from 194 stations in the United States and its territories. Approximately 90% of the components derived could be interpreted as falling into one of three categories - acid, salt, or an agricultural/soil association. The total mass, or the mass of any one solute, was apportioned among these components by multiple linear regression techniques. The use of multisolute components for determining trends or spatial distribution represents a substantial improvement over single-solute analysis in that these components are more directly related to the sources of the deposition. The geographic patterns displayed by the components in this analysis indicate a far more important role for acid deposition in the Southeast and intermountain regions of the United States than would be indicated by maps of sulfate or nitrate deposition alone. In the Northeast and Midwest, the acid component is not declining at most stations, as would be expected from trends in sulfate deposition, but is holding constant or increasing. This is due, in part, to a decline in the agriculture/soil factor throughout this region, which would help to neutralize the acidity.
NASA Astrophysics Data System (ADS)
Muley, G. G.; Naik, A. B.; Gambhire, A. B.
2014-06-01
Zinc tris-thiourea sulphate (ZTS) is a well known nonlinear optical (NLO) crystal widely used for various NLO applications. The NLO, physical and chemical properties can be modified by adding impurities and/or modifying crystal growth conditions. The impurities present in the growth solution and growth conditions can affect the crystal growth parameters at great extent. Thus, the study on the nature of intermolecular interaction with the dopant in the solution during crystal growth process becomes important. In the present investigation, the ultrasonic velocity was measured in the aqueous solutions of pure and cadmium sulphate mixed ZTS in the supersaturation state at 313.15 K. The thermodynamic parameters such as adiabatic compressibility, inter molecular free length, acoustic impedance and relative associations have been calculated from the ultrasonic data and densities of water and solutions at 313.15 K, and the nature of intermolecular interaction has been discussed. FT-IR spectra of all mixtures in the solid form at room temperature were recorded and the shifts in the absorption peaks corresponding to the functional groups of ZTS have been reported.
Test profiles for stationary energy-storage applications
NASA Astrophysics Data System (ADS)
Butler, P. C.; Cole, J. F.; Taylor, P. A.
Evaluation of battery and other energy-storage technologies for stationary uses is progressing rapidly toward application-specific testing. This testing uses computer-based data acquisition and control equipment, active electronic loads and power supplies, and customized software, to enable sophisticated test regimes which simulate actual use conditions. These simulated-use tests provide more accurate performance and life evaluations than simple constant resistance or current testing regimes. Several organizations are cooperating to develop simulated-use tests for utility-scale storage systems, especially battery energy-storage systems (BESSs). Some of the tests use stepped constant-power charge and discharge regimes to simulate conditions created by electric utility applications such as frequency regulation (FR) and spinning reserve (SR). Other test profiles under development simulate conditions for the energy-storage component of remote-area power supplies (RAPSs) which include renewable and/or fossil-fuelled generators. Various RAPS applications have unique sets of service conditions that require specialized test profiles. Almost all RAPS tests and many tests that represent other stationary applications need, however, to simulate significant time periods that storage devices operate at low-to-medium states-of-charge without full recharge. Consideration of these and similar issues in simulated-use test regimes is necessary to predict effectively the responses of the various types of batteries in specific stationary applications. This paper describes existing and evolving stationary applications for energy-storage technologies and test regimes which are designed to simulate them. The paper also discusses efforts to develop international testing standards.
Pati, Y Anusooya; Ramasesha, S
2014-06-12
Tetracene is an important conjugated molecule for device applications. We have used the diagrammatic valence bond method to obtain the desired states, in a Hilbert space of about 450 million singlets and 902 million triplets. We have also studied the donor/acceptor (D/A)-substituted tetracenes with D and A groups placed symmetrically about the long axis of the molecule. In these cases, by exploiting a new symmetry, which is a combination of C2 symmetry and electron-hole symmetry, we are able to obtain their low-lying states. In the case of substituted tetracene, we find that optically allowed one-photon excitation gaps reduce with increasing D/A strength, while the lowest singlet-triplet gap is only weakly affected. In all the systems we have studied, the excited singlet state, S1, is at more than twice the energy of the lowest triplet state and the second triplet is very close to the S1 state. Thus, donor-acceptor-substituted tetracene could be a good candidate in photovoltaic device application as it satisfies energy criteria for singlet fission. We have also obtained the model exact second harmonic generation (SHG) coefficients using the correction vector method, and we find that the SHG responses increase with the increase in D/A strength. PMID:24842608
Feinberg-Horodecki states of a time-dependent mass distribution harmonic oscillator
NASA Astrophysics Data System (ADS)
Eshghi, M.; Sever, R.; Ikhdair, S. M.
2016-07-01
The solution of the Feinberg-Horodecki (FH) equation for a time-dependent mass (TDM) harmonic oscillator quantum system is studied. A certain interaction is applied to a mass m(t) to provide a particular spectrum of stationary energies. The related spectrum of the harmonic oscillator potential V(t) acting on the TDM m(t) oscillators is found. We apply the time version of the asymptotic iteration method (AIM) to calculate analytical expressions of the TDM stationary state energies and their wave functions. It is shown that the obtained solutions reduce to those of simple harmonic oscillator as the time-dependent mass reduces to m0.
Jehle, Stefan; van Rossum, Barth; Stout, Joseph R.; Noguchi, Satoshi R.; Falber, Katja; Rehbein, Kristina; Oschkinat, Hartmut; Klevit, Rachel E.; Rajagopal, Ponni
2009-01-01
Summary Atomic level structural information on αB-Crystallin (αB), a prominent member of the small Heat Shock Protein (sHSP) family has been a challenge to obtain due its polydisperse, oligomeric nature. We show that magic-angle spinning solid-state NMR can be used to obtain high-resolution information on ∼ 580 kDa human αB assembled from 175-residue, 20 kDa subunits. An ∼100-residue α-crystallin domain is common to all sHSPs and solution-state NMR was performed on two different α-crystallin domain constructs isolated from αB. In vitro, the chaperone-like activities of full-length αB and the isolated α-crystallin domain are identical. Chemical shifts of the backbone and the Cβ resonances have been obtained for residues 64-162 (α-crystallin domain plus part of the C-terminus) in αB and the isolated α-crystallin domain by solid- and solution-state NMR, respectively. Both sets of data strongly predict six β-strands in the α-crystallin domain. A majority of residues in the α-crystallin domain have similar chemical shifts in both solid- and solution-state indicating a similar structure for the domain in its isolated and oligomeric forms. Sites of inter-subunit interaction are identified from chemical shift differences that cluster to specific regions of the α-crystallin domain. Multiple signals are observed for the resonances of M68 in the oligomer, identifying the region containing this residue as existing in heterogeneous environments within αB. Evidence for a novel dimerization motif in the human α-crystallin domain is obtained by a comparison of (i) solid- and solution-state chemical shift data and (ii) 1H-15N HSQC spectra as a function of pH. The isolated α-crystallin domain undergoes a dimer-monomer transition over the pH range of 7.5 to 6.8. This steep pH-dependent switch may be important for αB to function optimally, e.g., to preserve the filament integrity of cardiac muscle proteins such as actin and desmin during cardiac ischemia which
NASA Technical Reports Server (NTRS)
Short, N. M.
1980-01-01
To aid state/local agencies in starting effective programs to apply Landsat and other remote sensing data, NASA's Eastern Regional Remote Sensing Applications Center (ERRSAC) has developed a comprehensive training program as part of its technology transfer mission. Skills in data processing and interpretation are produced through 'hands-on' experience with computer techniques used to conduct practical applications involving state-oriented projects, conducted jointly by agencies and ERRSAC. In time, ERRSAC will shift much of these training activities to universities where future agency personnel can obtain a broader foundation in remote sensing.
Recursive solution of number of reachable states of a simple subclass of FMS
NASA Astrophysics Data System (ADS)
Chao, Daniel Yuh
2014-03-01
This paper aims to compute the number of reachable (forbidden, live and deadlock) states for flexible manufacturing systems (FMS) without the construction of reachability graph. The problem is nontrivial and takes, in general, an exponential amount of time to solve. Hence, this paper focusses on a simple version of Systems of Simple Sequential Processes with Resources (S3PR), called kth-order system, where each resource place holds one token to be shared between two processes. The exact number of reachable (forbidden, live and deadlock) states can be computed recursively.
Structural-energy states of water and aqueous solutions under external influences
NASA Astrophysics Data System (ADS)
Gorlenko, Nikolay; Laptev, Boris; Sidorenko, Galina; Sarkisov, Yuri; Minakova, Tamara; Kylchenko, Anton; Zubkova, Olga
2016-01-01
Methods are proposed for evaluating changes in the structure of water or aqueous electrolyte solutions under the influence of temperature, magnetic field and surface material by means of determining the electrical capacity of the liquid and the quality factor of the anti-resonant circuit in the frequency range from 1 kHz to 3000 kHz. The condenser plates in different types of electrochemical cells are placed one in front of the other, each at a distance of more than 5 cm, or relative to each other in parallel planes, or in one plane in which case the liquid is located on the condenser plates. The current density on the plates in various cells ranged from 10 to 100 nA/cm2. When measuring the electrical capacity, the voltage applied to the plates was reduced in proportion to the increase in the frequency of oscillator. The apparatus allows us to increase the dynamic range of the signal change from an electrochemical cell, reduce the impact of measurements on the structure of liquids, and also evaluate the direction and extent of changes in the structure of water and aqueous solutions under various external influences. Criteria are proposed for evaluating the structure of fluids.
ERIC Educational Resources Information Center
Redding, Sam; Nafziger, Dean
2013-01-01
The purpose of the state education agency (SEA) is to focus the entire education system on helping students become capable in college and career in an increasingly complex world. One of the most vexing problems facing SEAs today is how to meet increasing demands for performance while adjusting to significant resource reductions. Meeting that…
Analytical steady-state solutions for water-limited cropping systems using saline irrigation water
Technology Transfer Automated Retrieval System (TEKTRAN)
Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems mod...
States' Perspectives on Waivers: Relief from NCLB, Concern about Long-Term Solutions
ERIC Educational Resources Information Center
McMurrer, Jennifer; Yoshioka, Nanami
2013-01-01
On February 9, 2012, U.S. Secretary of Education Arne Duncan granted 10 states waivers of key accountability requirements of the Elementary and Secondary Education Act (ESEA), as amended by the No Child Left Behind (NCLB) Act. One year later, applications for this ESEA flexibility, also known as NCLB waivers, had been approved for an additional 24…
ERIC Educational Resources Information Center
Libler, Rebecca
2010-01-01
The Indiana State University Professional Development Schools (ISU PDS) Partnership sprang from the convergence of two strong needs: (1) the need for real life practice in the way of extended clinical experiences for teacher education students in schools of practice; and (2) the need on the part of the schools in the community to have access to…
Solutions to locoweed poisoning in New Mexico and the Western United States
Technology Transfer Automated Retrieval System (TEKTRAN)
A collaborative locoweed research effort between New Mexico State University and the USDA/ARS Poison Plant Lab was initiated in 1990 as a result of a “grass root” producer effort and a congressional appropriation, thanks to the efforts of NM Congressman Joe Skeen. A symposium was held at the SRM an...
Charters as a Solution?: So Far, States and Districts Have Opted for Anything But
ERIC Educational Resources Information Center
Smith, Nelson
2007-01-01
"Reopening the school as a public charter school" is Option #1 on the list of NCLB's restructuring alternatives for failing schools. But this has not proved a popular choice. NCLB made the bold assumption that states and districts would voluntarily turn over the reins to charter operators. The authors of the legislation must have thought, with so…
Interactions between an idealized rotating string and stationary constraints
NASA Astrophysics Data System (ADS)
Yang, L.; Hutton, S. G.
1995-08-01
In this paper the dynamic interactions between an idealized rotating circular string and a stationary constraint, consisting of a spring, a damper, a mass or a frictional restraint, are discussed. The method of travelling waves is applied to develop the characteristic equation, and it is shown that this method is more general than the conventional method of separation of variables. The response of the string at its critical speed is examined, and it is shown that at the critical speed the string cannot vibrate freely. An approximate solution is generated using the Galerkin method to solve the eigenvalues effectively. The physics of the interactions between the string and the restraints is discussed on the basis of both analytical and approximate solutions.
The magnetic-field structure in a stationary accretion disk
NASA Astrophysics Data System (ADS)
Piotrovich, M. Yu.; Silant'ev, N. A.; Gnedin, Yu. N.; Natsvlishvili, T. M.; Buliga, S. D.
2016-05-01
The magnetic-field structure in regions of stationary, planar accretion disks around active galactic nuclei where general-relativistic effects can be neglected (from 10 to 200 gravitational radii) is considered. It is assumed that the magnetic field in the outer edges of the disk, which forms in the magnetosphere of the central black hole during the creation of the relativisitic jets, corresponds to the field of a magnetic dipole perpendicular to the plane of the disk. In this case, the azimuthal field component B φ in the disk arises due to the presence of the radial field B ρ and the azimuthal velocity component U φ . The value of the magnetic field at the inner radius of the disk is taken to correspond to the solution of the induction equation in a diffusion approximation. Numerical solutions of the induction equation are given for a number of cases.
Cook, B H; Leigh, W J; Walsh, R
2001-06-01
Quantum yields for photochemical ring opening of six alkylcyclobutenes have been measured in hexane solution using 228-nm excitation, which selectively populates the lowest pi,R(3s) excited singlet states of these molecules and has been shown previously to lead to ring opening with clean conrotatory stereochemistry. The compounds studied in this work-1,2-dimethylcyclobutene (1), cis- and trans-1,2,3,4-tetramethylcyclobutene (cis- and trans-5), hexamethylcyclobutene (8), and cis- and trans-tricyclo[6.4.0.0(2,7)]dodec-1(2)-ene (cis- and trans-9)-were selected so as to span a broad range in molecular weight and as broad a range as possible in Arrhenius parameters for thermal (ground-state) ring opening. RRKM calculations have been carried out to provide estimates of the rate constants for ground-state ring opening of each of the compounds over a range of thermal energies from 20 000 to 49 000 cm(-1). These have been used to estimate upper limits for the quantum yields of ring opening via a hot ground-state mechanism, assuming a value of k(deact) = 10(11) s(-1) for the rate constant for collisional deactivation by the solvent, that internal conversion to the ground state from the lowest Rydberg state occurs with close to unit efficiency, and that ergodic behavior is followed. The calculated quantum yields are significantly lower than the experimental values in all cases but one (1). This suggests that the Rydberg-derived ring opening of alkylcyclobutenes is a true excited-state process and rules out the hot ground-state mechanism for the reaction. PMID:11457380
An, Hui-Ying; Ma, Chensheng; Nganga, Jameil L; Zhu, Yue; Dore, Timothy M; Phillips, David Lee
2009-03-26
The 8-bromo-7-hydroxyquinolinyl group (BHQ) is a derivative of 7-hydroxyquinoline (7-HQ) and BHQ molecules coexisting as different forms in aqueous solution. Absorption and resonance Raman spectroscopic methods were used to examine 8-bromo-7-hydroxyquinoline protected acetate (BHQ-OAc) in acetonitrile (MeCN), H(2)O/MeCN (60:40, v/v, pH 6 approximately 7), and NaOH-H(2)O/MeCN (60:40, v/v, pH 11 approximately 12) to obtain a better characterization of the forms of the ground-state species of BHQ-OAc in aqueous solutions and to examine their properties. The absorption spectra of BHQ-OAc in water show no absorption bands of the tautomeric species unlike the strong band at about 400 nm observed for the tautomeric form in 7-HQ aqueous solution. The resonance Raman spectra in conjunction with Raman spectra predicted from density functional theory (DFT) calculations reveal the observation of a double Raman band system characteristic of the neutral form (the nominal C=C ring stretching, C-N stretching, and O-H bending modes at 1564 and 1607 cm(-1)) and a single Raman band diagnostic of the enol-deprotonated anionic form (the nominal C=C ring, C-N, and C-O(-) stretching modes in the 1593 cm(-1) region). These results suggest that the neutral form of BHQ-OAc is the major species in neutral aqueous solution. There is a modest increase in the amount of the anionic form and a big decrease in the amount of the tautomeric form of the molecules for BHQ-OAc compared to 7-HQ in neutral aqueous solution. The presence of the 8-bromo group and/or competitive hydrogen bonding that hinder the formation and transfer process of a BHQ-OAc-water cyclic complex may be responsible for this large substituent effect. PMID:19296708
Solid-State and Solution Structures of Glycinimine-Derived Lithium Enolates.
Jin, Kyoung Joo; Collum, David B
2015-11-18
A combination of crystallographic, spectroscopic, and computational studies was applied to study the structures of lithium enolates derived from glycinimines of benzophenone and (+)-camphor. The solvents examined included toluene and toluene containing various concentrations of tetrahydrofuran, N,N,N',N'-tetramethylethylenediamine (TMEDA), (R,R)-N,N,N',N'-tetramethylcyclohexanediamine [(R,R)-TMCDA], and (S,S)-N,N,N',N'-tetramethylcyclohexanediamine [(S,S)-TMCDA]. Crystal structures show chelated monomers, symmetric disolvated dimers, S4-symmetric tetramers, and both S6- and D3d-symmetric hexamers. (6)Li NMR spectroscopic studies in conjunction with the method of continuous variations show how these species distribute in solution. Density functional theory computations offer insights into experimentally elusive details. PMID:26554898
Multiple protein stationary phases: a review.
Singh, N S; Habicht, K-L; Dossou, K S S; Shimmo, R; Wainer, I W; Moaddel, R
2014-10-01
Cellular membrane affinity chromatography stationary phases have been extensively used to characterize immobilized proteins and provide a direct measurement of multiple binding sites, including orthosteric and allosteric sites. This review will address the utilization of immobilized cellular and tissue fragments to characterize multiple transmembrane proteins co-immobilized onto a stationary phase. This approach will be illustrated by demonstrating that multiple transmembrane proteins were immobilized from cell lines and tissue fragments. In addition, the immobilization of individual compartments/organelles within a cell will be discussed and the changes in the proteins binding/kinetics based on their location. PMID:24780640
Banyasz, Akos; Gustavsson, Thomas; Onidas, Delphine; Changenet-Barret, Pascale; Markovitsi, Dimitra; Improta, Roberto
2013-03-11
The singlet excited states of adenine oligomers, model systems widely used for the understanding of the interaction of ultraviolet radiation with DNA, are investigated by fluorescence spectroscopy and time-dependent (TD) DFT calculations. Fluorescence decays, fluorescence anisotropy decays, and time-resolved fluorescence spectra are recorded from the femtosecond to the nanosecond timescales for single strand (dA)20 in aqueous solution. These experimental observations and, in particular, the comparison of the fluorescence behavior upon UVC and UVA excitation allow the identification of various types of electronic transitions with different energy and polarization. Calculations performed for up to five stacked 9-methyladenines, taking into account the solvent, show that different excited states are responsible for the absorption in the UVC and UVA spectral domains. Independently of the number of bases, bright excitons may evolve toward two types of excited dimers having π-π* or charge-transfer character, each one distinguished by its own geometry and spectroscopic signature. According to the picture arising from the joint experimental and theoretical investigation, UVC-induced fluorescence contains contribution from 1) exciton states with a different degree of localization, decaying within a few ps, 2) "neutral" excited dimers decaying on the sub-nanosecond timescale, being the dominant species, and 3) charge-transfer states decaying on the nanosecond timescale. The majority of the photons emitted upon UVA excitation are related to charge-transfer states. PMID:23335234
Laussac, J P; Cung, M T; Pasdeloup, M; Haran, R; Marraud, M; Lefrancier, P; Dardenne, M; Bach, J F
1986-06-15
The nonapeptide less than Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn (formerly called serum thymic factor) is a factor produced by the thymic epithelium, which needs a zinc ion to express its immunoregulatory properties. We report here on 1H and 13C NMR investigation of the conformational properties of the free peptide in aqueous medium and in dimethyl sulfoxide-d6 solution by a combination of homo- and heteronuclear one- and two-dimensional experiments. The various resonances have been assigned in a straightforward manner on the basis of 1H,1H COSY spectroscopy for the recognition of the proton spin systems; two-dimensional NOESY spectra with the correlation peaks across amide bonds and for the amino acid sequence assignment; amide bonds and for the amino acid sequence assignment; 13C,1H COSY experiments using selective polarization transfer from 1H- to 13C-nucleus via the 13C,1H long-range couplings for the attribution of the carboxyl and carbonyl groups; and 13C,1H COSY experiments with selective polarization transfer via the 13C,1H direct couplings for the assignment of all the aliphatic carbons. Other experiments such as pH-dependent chemical shifts, combined use of multiple and selective proton-decoupled 1H and 13C NMR spectra, the temperature and the concentration dependence of the proton shifts of the amide resonances, the solvent dependences of peptide carbonyl carbon resonances, and comparison of the spectra with three different analogues were performed. In aqueous solution, the data are compatible with the assumption of a highly mobile dynamic equilibrium among different conformations, whereas in dimethyl sulfoxide-d6, a more rigid structure is found involving three internal hydrogen bonds. These observations provide an insight into the conformational tendencies of this peptidic hormone in two different media. PMID:3711109
Solid state and solution studies of lithium tris(n-butyl)magnesiates stabilised by Lewis donors.
Zaragoza-Calero, Silvia; Francos, Javier; Kennedy, Alan R; O'Hara, Charles T
2015-04-28
Several Lewis base adducts of the synthetically important lithium tris(n-butyl)magnesiate LiMg((n)Bu)3 have been prepared and structurally characterised. The complexes were prepared by a co-complexation approach i.e., by combining the monometallic (n)BuLi and (n)Bu2Mg reagents in hydrocarbon solution before adding a molar equivalent of a donor molecule (a bidentate amine, tridentate amine or cyclic ether). The lithium magnesiates all adopt variants of the "Weiss motif" structure, i.e., contacted ion pair dimers with a linear arrangement and metals connected by butyl anions, where tetrahedral magnesium ions are in the central positions and the lithiums occupy the outer region, solvated by a neutral Lewis donor [(donor)Li(μ-(n)Bu)2Mg(μ-(n)Bu)2Mg(μ-(n)Bu)2Li(donor)]. When TMPDA, PMDETA or (R,R)-TMCDA [TMPDA = N,N,N'N'-tetramethylpropanediamine; PMDETA = N,N,N',N'',N''-pentamethyldiethylenetriamine; and (R,R)-TMCDA = (R,R)-N,N,N',N'-tetramethylcyclohexane-1,2-diamine], are employed, dimeric tetranuclear lithium magnesiates are produced. Due to the tridentate nature of the ligand, the PMDETA-containing structure (2) has an unusual 'open'-motif. When TMEDA (TMEDA = N,N,N',N'-tetramethylethylenediamine) is employed, a n-butoxide-containing complex [(TMEDA)Li(μ-(n)Bu)(μ-O(n)Bu)Mg2((n)Bu)2(μ-(n)Bu)(μ-O(n)Bu)Li(donor)] has been serendipitously prepared and adopts a ladder conformation which is commonly observed in lithium amide chemistry. This complex has also been prepared using a rational methodology. When 1,4-dioxane is employed, the donor stitches together a polymeric array of tetranuclear dimeric units (6). The hydrocarbon solution structures of the compounds have been characterised by (1)H, (7)Li, (13)C NMR spectroscopy; 2 has been studied by variable temperature and DOSY NMR. PMID:25791270
NASA Astrophysics Data System (ADS)
Si, Jianguo; Ma, Minghuan
2007-03-01
This paper is concerned with a functional differential equation of the formx'(z)=1/x(az+bx'(z)) with the distinctive feature that the argument of the unknown function depends on the state derivative, where a,b are two complex numbers. By reducing the equation with the Schroder transformation to another functional differential equation with proportional delay, we give existence of its local invertible analytic solutions. We discuss not only that the constant [alpha] given in Schroder transformation at resonance, i.e., at a root of the unity, but also those [alpha] near resonance (near a root of the unity) under the Brjuno condition.
NASA Astrophysics Data System (ADS)
Nazarov, L. A.; Nazarova, L. A.; Romenskii, E. I.; Tcheverda, V. A.; Epov, M. I.
2016-02-01
A method for estimating the stress-strain state of a rock massif in the vicinity of underground facilities is substantiated. This method is based on solution of the boundary inverse problem of defining the components of an external stress field from the acoustic sounding data. The acoustic sounding data used are the arrival times of diving head longitudinal waves, recorded in a long mine shaft. Numerical experiments have revealed the optimal arrangement of the recording network and the limited relative error in the input data, which, taken together, provide for solvability of the inverse problem.
NASA Astrophysics Data System (ADS)
Glibitskiy, Gennadiy; Glibitskiy, Dmitriy; Gorobchenko, Olga; Nikolov, Oleg; Roshal, Alexander; Semenov, Mikhail; Gasan, Anatoliy
2015-03-01
The formation of the textures on the surface of the films from the solutions of bovine serum albumin (BSA) with sodium halides (NaF, NaCl, and NaBr) of various concentrations was studied. The formation of symmetric zigzag textures on the surface of BSA films (Cryst Eng 3:173-194, 2000) in the presence of sodium halides depends on the conformational state of the protein globule. Thermal denaturation of BSA also did not allow to form zigzag textures on the surface of the films.
NASA Astrophysics Data System (ADS)
Gojani, A. B.; Ohtani, K.; Takayama, K.; Hosseini, S. H. R.
2016-01-01
This paper reports a result of experiments for the determination of reliable shock Hugoniot curves of liquids, in particular, at relatively low pressure region, which are needed to perform precise numerical simulations of shock wave/tissue interaction prior to the development of shock wave related therapeutic devices. Underwater shock waves were generated by explosions of laser ignited 10 mg silver azide pellets, which were temporally and spatially well controlled. Measuring temporal variation of shock velocities and over-pressures in caster oil, aqueous solutions of sodium chloride, sucrose and gelatin with various concentrations, we succeeded to determine shock Hugoniot curves of these liquids and hence parameters describing Tait type equations of state.
NASA Astrophysics Data System (ADS)
Zheng, Jiajin; Guo, Yangxue; Li, Xiangpin; Zhang, Guilan; Chen, Wenju
2006-10-01
The two-photon-induced excited state intramolecular proton transfer (ESIPT) process of 2-(2'-hydroxyphenyl) benzothiazole (HBT) in cyclohexane solution has been investigated. We focus on the calculation of the two-photon absorption (TPA) coefficient and nonlinear refraction index of HBT, and the theoretical computational results are in good agreement with the experimental ones. By establishing the ESIPT kinetic model for HBT based on TPA, the TPA cross section is obtained. The numerical results show that HBT exhibits a rather large TPA cross section compared with that of 2-(2'-hydroxyphenyl)benzoxazole (HBO) reported previously. Therefore, HBT is a promising TPA material and is worthy of further research.
Solution-state molecular structure of apo and oleate-liganded liver fatty acid-binding protein.
He, Yan; Yang, Xiaomin; Wang, Hsin; Estephan, Rima; Francis, Fouad; Kodukula, Sarala; Storch, Judith; Stark, Ruth E
2007-11-01
Rat liver fatty acid-binding protein (LFABP) is distinctive among intracellular lipid-binding proteins (iLBPs): more than one molecule of long-chain fatty acid and a variety of diverse ligands can be bound within its large cavity, and in vitro lipid transfer to model membranes follows a mechanism that is diffusion-controlled rather than mediated by protein-membrane collisions. Because the apoprotein has proven resistant to crystallization, nuclear magnetic resonance spectroscopy offers a unique route to functionally informative comparisons of molecular structure and dynamics for LFABP in free (apo) and liganded (holo) forms. We report herein the solution-state structures determined for apo-LFABP at pH 6.0 and for holoprotein liganded to two oleates at pH 7.0, as well as the structure of the complex including locations of the ligands. 1H, 13C, and 15N resonance assignments revealed very similar types and locations of secondary structural elements for apo- and holo-LFABP as judged from chemical shift indices. The solution-state tertiary structures of the proteins were derived with the CNS/ARIA computational protocol, using distance and angular restraints based on 1H-1H nuclear Overhauser effects (NOEs), hydrogen-bonding networks, 3J(HNHA) coupling constants, intermolecular NOEs, and residual dipolar (NH) couplings. The holo-LFABP solution-state conformation is in substantial agreement with a previously reported X-ray structure [Thompson, J., Winter, N., Terwey, D., Bratt, J., and Banaszak, L. (1997) The crystal structure of the liver fatty acid-binding protein. A complex with two bound oleates, J. Biol. Chem. 272, 7140-7150], including the typical beta-barrel capped by a helix-turn-helix portal. In the solution state, the internally bound oleate has the expected U-shaped conformation and is tethered electrostatically, but the extended portal ligand can adopt a range of conformations based on the computationally refined structures, in contrast to the single
Light quenching and dark states in colloidal solutions of semiconductor CdSe/ZnS quantum dots
NASA Astrophysics Data System (ADS)
Danilov, V. V.; Panfutova, A. S.; Shilov, V. B.; Belousova, I. M.; Ermolaeva, G. M.; Khrebtov, A. I.
2014-06-01
The photodynamics of optical limiting in colloidal solutions of different-size CdSe/ZnS quantum dots is studied. The behavior of the dependences points to a multistage process that includes the bleaching and optical limiting stages. The limiting photodynamics is compared with luminescence dynamics of quantum dots under conditions of high-power excitation. It is shown that the optical limiting efficiency in such media is determined by the position of exciting radiation with respect to the main exciton absorption band of the quantum dot. The roles played by so-called dark states and light quenching in limiting photodynamics are discussed.
The application of the nonsmooth critical point theory to the stationary electrorheological fluids
NASA Astrophysics Data System (ADS)
Qian, Chenyin
2016-06-01
In this paper, we prove the existence of variational solutions to systems modeling electrorheological fluids in the stationary case. Our method of proof is based on the nonsmooth critical point theory for locally Lipschitz functional and the properties of the generalized Lebesgue-Sobolev space.
NASA Astrophysics Data System (ADS)
Andreis, Luisa; Barbato, David; Collet, Francesca; Formentin, Marco; Provenzano, Luigi
2016-03-01
We consider an inviscid stochastically forced dyadic model, where the additive noise acts only on the first component. We prove that a strong solution for this problem exists and is unique by means of uniform energy estimates. Moreover, we exploit these results to establish strong existence and uniqueness of the stationary distribution.
X-ray line shapes of metals: Exact solutions of a final-state interaction model
NASA Astrophysics Data System (ADS)
Swarts, Coenraad A.; Dow, John D.
2005-10-01
By means of model calculations for an independent-electron metal, we obtain exact line shapes for the photon absorption, emission, and photoemission spectra of core states, including electronic relaxation. In all cases we find an x-ray edge anomaly. For the absorption and emission spectra this anomaly is superposed on a continuum resembling Elliott exciton theory. We display how the spectra evolve from the exciton limit to the free-electron limit as the final-state interaction strength is decreased or the Fermi energy increased. We compare the spectra obtained for different final-state interactions and find that different types of interactions produce different spectral shapes. Away from threshold the absorption and emission profiles show an enhancement of the free-electron result, as predicted by the screened-exciton theory. Our results offer potential explanations for (i) incompatibilities between threshold exponents and exponents extracted from other data, (ii) the occurrence of nearly symmetric x-ray photoemission lines, and (iii) the lack of mirror symmetry of absorption and emission edges.
Superconducting PM undiffused machines with stationary superconducting coils
Hsu, John S.; Schwenterly, S. William
2004-03-02
A superconducting PM machine has a stator, a rotor and a stationary excitation source without the need of a ferromagnetic frame which is cryogenically cooled for operation in the superconducting state. PM material is placed between poles on the rotor to prevent leakage or diffusion of secondary flux before reaching the main air gap, or to divert PM flux where it is desired to weaken flux in the main air gap. The PM material provides hop-along capability for the machine in the event of a fault condition.
NASA Astrophysics Data System (ADS)
Babür, Banu; Seferoğlu, Nurgül; Aktan, Ebru; Hökelek, Tuncer; Şahin, Ertan; Seferoğlu, Zeynel
2015-02-01
A new two series of phenylazo indole dyes was synthesized and the structures of the dyes were confirmed by UV-vis, FT-IR, HRMS and 1H/13C NMR spectroscopic techniques. Five of these dyes (I, I‧, II‧, III and III‧) were also characterized in solid state by using single crystal X-ray diffraction studies besides other spectroscopic techniques. The geometries of the azo and hydrazone tautomeric forms of the dyes were optimized by using Density Functional Theory (DFT). In addition, the effects of the donor and acceptor groups on the azo and hydrazone forms of the dyes were evaluated experimentally and theoretically. The results indicate that the phenylazoindole dyes derived from 2-phenyl indole as coupling component exist as azo form in solution, gas phase and solid state.
MULTIPLE METALS STACK EMISSION MEASUREMENT METHODOLOGY FOR STATIONARY SOURCES, CURRENT STATUS
Stack emissions of metals from stationary sources are of present interest to the United States Environmental Protection Agency (USEPA), to state and local governments, to industries, and to the public. hen regulations require limitation of metals stack emissions, it follows logic...
MULTIPLE METALS STACK EMISSION MEASUREMENT METHODOLOGY FOR STATIONARY SOURCES - CURRENT STATUS
Stack emissions of metals from stationary sources are of present interest to the United States Environmental Protection Agency (USEPA), to state and local governments, to industries, and to the public. hen regulations require limitation of metals stack emissions, it follows logic...
Spin states of cobalt and the thermodynamics of Sm1 - x Ca x CoO3 - δ solid solutions
NASA Astrophysics Data System (ADS)
Vasil'chikova, T. N.; Kuz'mova, T. G.; Kamenev, A. A.; Kaul', A. R.; Vasil'ev, A. N.
2013-03-01
In the rare-earth SmCoO3 perovskite, Co3+ ions at low temperatures appear to be in the low-spin state with S = 0, t {2/g 2} e {/g 0}. If Ca2+ ions partially substitute Sm3+ ions, oxygen deficient Sm1 - x Ca x CoO3 - δ solid solutions with δ = x/2 appear. The oxygen deficiency leads to the formation of pyramidally coordinated cobalt ions Co{pyr/3+} in addition to the existing cobalt ions Co{oct/3+} within the oxygen octahedra. Even at low temperatures, these ions have a magnetic state, either S = 1, t {2/g 5} e {/g 1} or S = 2, t {2/g 4} e {/g 2}. At low temperatures, the magnetization of Sm1 - x Ca x CoO3 - δ is mainly determined by the response of Co{pyr/3+} ions. Owing to the characteristic features of the crystal structure of the oxygen deficient perovskite, these ions form a set of nearly isolated dimers. At high temperatures, the magnetization of Sm1 - x Ca x CoO3 - δ is mainly determined by the response of Co{oct/3+} ions, which exhibit a tendency to undergo the transition from the S = 0, t {2/g 6} e {/g 0} state to the S = 1, t {2/g 5} e {/g 1} or S = 2, tt {2/g 4} e {/g 2} state. In addition, the magnetization and specific heat of the solid solutions under study include the contribution from the rare-earth subsystem, which undergoes a magnetic ordering at low temperatures.
NASA Astrophysics Data System (ADS)
Vance, S.; Brown, J. M.; Bollengier, O.; Journaux, B.; Sotin, C.; Choukroun, M.; Barnes, R.
2014-12-01
Supporting life in icy world or exoplanet oceans may require global seafloor chemical reactions between water and rock. Such interactions have been regarded as limited in larger icy worlds such as Ganymede and Titan, where ocean depths approach 800 km and GPa pressures (>10katm). If the oceans are composed of pure water, such conditions are consistent with the presence of dense ice phases V and VI that cover the rocky seafloor. Exoplanets with oceans can obtain pressures sufficient to generate ices VII and VIII. We have previously demonstrated temperature gradients in such oceans on the order of 20 K or more, resulting from fluid compressibility in a deep adiabatic ocean based on our experimental work. Accounting for increases in density for highly saline oceans leads to the possibility of oceans perched under and between high pressure ices. Ammonia has the opposite effect, instead decreasing ocean density, as reported by others and confirmed by our laboratory measurements in the ammonia water system. Here we report on the completed equation of state for aqueous ammonia derived from our prior measurements and optimized global b-spline fitting methods We use recent diamond anvil cell measurements for water and ammonia to extend the equation of state to 400°C and beyond 2 GPa, temperatures and pressures applicable to icy worlds and exoplanets. Densities show much less temperature dependence but comparabe high-pressure derivatives to previously published ammonia-water properties derived for application to Titan (Croft et al. 1988). Thermal expansion is in better agreement with the more self-consistent equation of state of Tillner-Roth and Friend (1998). We also describe development of a planetary NaCl equation of state using recent measurements of phase boundaries and sound speeds. We examine implications of realistic ocean-ice thermodynamics for Titan and exoplanet interiors using the methodology recently applied to Ganymede for oceans dominated by MgSO4. High
Solution-State One- and Two-Dimensional NMR Spectroscopy of High-Molecular-Weight Cellulose.
Holding, Ashley J; Mäkelä, Valtteri; Tolonen, Lasse; Sixta, Herbert; Kilpeläinen, Ilkka; King, Alistair W T
2016-04-21
High-molecular-weight celluloses (which even include bacterial cellulose) can be dissolved fully in methyltrioctylphosphonium acetate/[D6 ]DMSO solutions to allow the measurement of resonance-overlap-free 1 D and 2 D NMR spectra. This is achieved by a simple and non-destructive dissolution method, without solvent suppression, pre-treatment or deuteration of the ionic component. We studied a range of cellulose samples by using various NMR experiments to make an a priori assignment of the cellulose resonances. Chain-end resonances are also visible in the (1) H NMR spectrum. This allows the rough determination of the degree of polymerisation (DP) of a sample for low-DP celluloses by the integration of non-reducing chain ends C1 versus polymeric cellobiose C1. Low-DP celluloses show a good agreement with the gel-permeation chromatography (GPC) values, but high-DP pulps show more deviation. For high-purity pulps (pre-hydrolysis kraft and sulfite), residual xyloses and mannoses can also be identified from the (1) H-(13) C heteronuclear single-quantum coherence (HSQC) spectra. Resonances are thus assigned for the common polymeric polysaccharides found in chemical pulps. PMID:27010664
Aqueous solutions: state of the art in ab initio molecular dynamics.
Hassanali, Ali A; Cuny, Jérôme; Verdolino, Vincenzo; Parrinello, Michele
2014-03-13
The simulation of liquids by ab initio molecular dynamics (AIMD) has been a subject of intense activity over the last two decades. The significant increase in computational resources as well as the development of new and efficient algorithms has elevated this method to the status of a standard quantum mechanical tool that is used by both experimentalists and theoreticians. As AIMD computes the electronic structure from first principles, it is free of ad hoc parametrizations and has thus been applied to a large variety of physical and chemical problems. In particular, AIMD has provided microscopic insight into the structural and dynamical properties of aqueous solutions which are often challenging to probe experimentally. In this review, after a brief theoretical description of the Born-Oppenheimer and Car-Parrinello molecular dynamics formalisms, we show how AIMD has enhanced our understanding of the properties of liquid water and its constituent ions: the proton and the hydroxide ion. Thereafter, a broad overview of the application of AIMD to other aqueous systems, such as solvated organic molecules and inorganic ions, is presented. We also briefly describe the latest theoretical developments made in AIMD, such as methods for enhanced sampling and the inclusion of nuclear quantum effects. PMID:24516179
NASA Technical Reports Server (NTRS)
Wu, Kinwah; Chanmugam, G.; Shaviv, G.
1994-01-01
We present, for the first time, a closed integral-form solution to the accretion shock structures for the case where the cooling is due to optically thin bremsstrahlung emission and a series of power-law cooling functions of density and temperature. Our results can provide useful checks on numerical calculations and simple accurate estimates for valuable parameters such as the shock height. For the case where the cooling rate j = (2/3)Arho(exp 2)(P/rho)(exp 1/2)(1 + epsilon (sub s)(P/P(sub s)(exp alpha)(rho(sub s)/rho)(exp beta)), we find that a substantial amount of the accretion energy is released at the base of the accretion shock in the form of bremsstrahlung radiation. This implies that for a cyclotron-dominated shock (qualitatively given by alpha = 2.0, beta = 3.85, and epsilon(sub s) is much greater than 1), bremsstrahlung cooling still plays a crucial role in determining the shock structure. Our results are shown to be consistent with detailed numerical calculations.
The United States Environmental Protection Agency (USEPA) has listed inorganic arsenic emissions as a hazardous air pollutant. USEPA proposed Method 108 for the measurement of these emissions from stationary sources has been subjected to validation studies in this work. Laborator...
Solid state quantum computers: a nanoscopic solution to the Moore's law problem
NASA Astrophysics Data System (ADS)
Ng, Joseph; Abbott, Derek
2001-03-01
The computer industry has followed Moore's Law closely and faithfully over the past few decades. However, transistors cannot continue to shrink at their current rate forever, and new methods of computation must be explored. Quantum computation is one such method that has received much attention over the past few years and will heavily rely on technological advances in the smart electronics and nanotechnology arena. In this review, we will present some of the problems facing classical computers and why quantum computers may be a viable alternative. We will briefly describe some of the "killer" quantum applications, such as Deutsch's, Shor's and Grover's algorithms that demonstrate the computational powers of quantum computation. Kane's solid state quantum computer in silicon promises to demonstrate some of these applications. However there remain many significant technological difficulties which will need to be overcome if we are to see a useful quantum computer. The main technological challenges, for Kane's solid-state computer, of interest to the smart materials and structures community, will be highlighted.
Inclusion of Paracetamol into β-cyclodextrin nanocavities in solution and in the solid state
NASA Astrophysics Data System (ADS)
El-Kemary, Maged; Sobhy, Saffaa; El-Daly, Samy; Abdel-Shafi, Ayman
2011-09-01
We report on steady-state UV-visible absorption and emission characteristics of Paracetamol, drug used as antipyretic agent, in water and within cyclodextrins (CDs): β-CD, 2-hydroxypropyl- β-CD (HP- β-CD) and 2,6-dimethyl- β-CD (Me- β-CD). The results reveal that Paracetamol forms a 1:1 inclusion complex with CD. Upon encapsulation, the emission intensity enhances, indicating a confinement effect of the nanocages on the photophysical behavior of the drug. Due to its methyl groups, the Me- β-CD shows the largest effect for the drug. The observed binding constant showing the following trend: Me- β-CD > HP- β-CD > β-CD. The less complexing effectiveness of HP- β-CD is due to the steric effect of the hydroxypropyl-substituents, which can hamper the inclusion of the guest molecules. The solid state inclusion complex was prepared by co-precipitation method and its characterization was investigated by Fourier transform infrared spectroscopy, 1H NMR and X-ray diffractometry. These approaches indicated that Paracetamol was able to form an inclusion complex with CDs, and the inclusion compounds exhibited different spectroscopic features and properties from Paracetamol.
Charged particle tunnels from the stationary and non-stationary Kerr-Newman black holes
NASA Astrophysics Data System (ADS)
Chen, Deyou; Yang, Shuzheng
2007-09-01
Considering the unfixed background space-time and self-gravitational interaction, we view the Hawking radiation of a stationary Kerr-Newman black hole by Hamilton-Jacobi method. Meanwhile, extending this work to non-stationary black holes, we attempt to investigate the Hawking radiation of the non-stationary Kerr-Newman black hole. Both of the results show the tunneling probabilities are related to the change of Bekenstein- Hawking entropy and the radiation spectrums deviate from the purely thermal one, which is in accordance with the known result.
Diaferia, Carlo; Mercurio, Flavia Anna; Giannini, Cinzia; Sibillano, Teresa; Morelli, Giancarlo; Leone, Marilisa; Accardo, Antonella
2016-01-01
Water soluble fibers of PEGylated tetra-phenylalanine (F4), chemically modified at the N-terminus with the DOTA chelating agent, have been proposed as innovative contrast agent (CA) in Magnetic Resonance Imaging (MRI) upon complexation of the gadolinium ion. An in-depth structural characterization of PEGylated F4-fibers, in presence (DOTA-L6-F4) and in absence of DOTA (L6-F4), is reported in solution and at the solid state, by a multiplicity of techniques including CD, FTIR, NMR, DLS, WAXS and SAXS. This study aims to better understand how the aggregation process influences the performance of nanostructures as MRI CAs. Critical aggregation concentrations for L6-F4 (43 μM) and DOTA-L6-F4 (75 μM) indicate that self-aggregation process occurs in the same concentration range, independently of the presence of the CA. The driving force for the aggregation is the π-stacking between the side chains of the aromatic framework. CD, FTIR and WAXS measurements indicate an antiparallel β-sheet organization of the monomers in the resulting fibers. Moreover, WAXS and FTIR experiments point out that in solution the nanomaterials retain the same morphology and monomer organizations of the solid state, although the addition of the DOTA chelating agent affects the size and the degree of order of the fibers. PMID:27220817
Diaferia, Carlo; Mercurio, Flavia Anna; Giannini, Cinzia; Sibillano, Teresa; Morelli, Giancarlo; Leone, Marilisa; Accardo, Antonella
2016-01-01
Water soluble fibers of PEGylated tetra-phenylalanine (F4), chemically modified at the N-terminus with the DOTA chelating agent, have been proposed as innovative contrast agent (CA) in Magnetic Resonance Imaging (MRI) upon complexation of the gadolinium ion. An in-depth structural characterization of PEGylated F4-fibers, in presence (DOTA-L6-F4) and in absence of DOTA (L6-F4), is reported in solution and at the solid state, by a multiplicity of techniques including CD, FTIR, NMR, DLS, WAXS and SAXS. This study aims to better understand how the aggregation process influences the performance of nanostructures as MRI CAs. Critical aggregation concentrations for L6-F4 (43 μM) and DOTA-L6-F4 (75 μM) indicate that self-aggregation process occurs in the same concentration range, independently of the presence of the CA. The driving force for the aggregation is the π-stacking between the side chains of the aromatic framework. CD, FTIR and WAXS measurements indicate an antiparallel β-sheet organization of the monomers in the resulting fibers. Moreover, WAXS and FTIR experiments point out that in solution the nanomaterials retain the same morphology and monomer organizations of the solid state, although the addition of the DOTA chelating agent affects the size and the degree of order of the fibers. PMID:27220817
Kong, Weixin; Li, Baohui; Jin, Qinghua; Ding, Datong; Shi, An-Chang
2009-06-24
Multicompartment micelles, especially nanostructured vesicles, offer tremendous potential as delivery vehicles of therapeutic agents and nanoreactors. Solution-state self-assembly of miktoarm star terpolymers provides a versatile and powerful route to obtain multicompartment micelles. Here we report simulations of solution-state self-assembly of ABC star terpolymers composed of a solvophilic A arm and two solvophobic B and C arms. A variety of multicompartment micelles are predicted from the simulations. Phase diagrams for typical star terpolymers are constructed. It is discovered that the overall micelle morphology is largely controlled by the volume fraction of the solvophilic A arms, whereas the internal compartmented and/or segregated structures depend on the ratio between the volume fractions of the two solvophobic arms. The polymer-solvent and polymer-polymer interactions can be used to tune the effective volume fraction of the A-arm and, thereby, induce morphological transitions. For terpolymers with equal or nearly equal length of B and C arms, several previously unknown structures, including vesicles with novel lateral structures (helices or stacked donuts), segmented semivesicles, and elliptic or triangular bilayer sheets, are discovered. When the lengths of B and C arms are not equal, novel micelles such as multicompartment disks and onions are observed. PMID:19476352
Damping device for a stationary labyrinth seal
NASA Technical Reports Server (NTRS)
El-Aini, Yehia M. (Inventor); Mitchell, William S. (Inventor); Roberts, Lawrence P. (Inventor); Montgomery, Stuart K. (Inventor); Davis, Gary A. (Inventor)
2010-01-01
A stationary labyrinth seal system includes a seal housing having an annular cavity, a plurality of damping devices, and a retaining ring. The damping devices are positioned within the annular cavity and are maintained within the annular cavity by the retaining ring.
Optimal triple configurations of stationary shocks
NASA Astrophysics Data System (ADS)
Tao, G.; Uskov, V. N.; Chernyshov, M. V.
Shock-wave systems consisted of three stationary shocks with common (triple) point T (Fig. 1,a-e) are called triple configurations. The slipstream (τ) emanates from the triple point and divides the streams that have gone through the sequence of shocks 1-2 and through the alone (main) shock 3 at another side of the triple point.
Stationary Engineering. Science 2. Teachers Guide.
ERIC Educational Resources Information Center
Frost, Harold J.; Steingress, Frederick M.
This teachers guide to be used with the second-year student manual, "Stationary Engineering Science Manual--2," contains 140 lesson plans, corresponding to the lessons in the student manual. The lessons are brief and each involves concrete trade experiences where science is applied with 26 lessons also involving mathematical problems used in the…
NITROGEN OXIDE CONTROL FOR STATIONARY COMBUSTION SOURCES
Nitrogen dioxide is a criteria pollutant under the Clean Air Act and emissions of nitrogen oxides must be controlled to achieve attainment with the ambient standards. his handbook presents an overview of technologies that may be applicable to control the four major stationary sou...
Prima, Eka Cahya; Yuliarto, Brian; Suyatman; Dipojono, Hermawan Kresno
2015-09-30
The aglycones of anthocyanidin dyes were previously reported to form carbinol pseudobase, cis-chalcone, and trans-chalcone due to the basic levels. The further investigations of ground and excited state properties of the dyes were characterized using density functional theory with PCM(UFF)/B3LYP/6-31+G(d,p) level in the basic solutions. However, to the best of our knowledge, the theoretical investigation of their potential photosensitizers has never been reported before. In this paper, the theoretical photovoltaic properties sensitized by dyes have been successfully investigated including the electron injections, the ground and excited state oxidation potentials, the estimated open circuit voltages, and the light harvesting efficiencies. The results prove that the electronic properties represented by dyes’ LUMO-HOMO levels will affect to the photovoltaic performances. Cis-chalcone dye is the best anthocyanidin aglycone dye with the electron injection spontaneity of −1.208 eV, the theoretical open circuit voltage of 1.781 V, and light harvesting efficiency of 56.55% due to the best HOMO-LUMO levels. Moreover, the ethanol solvent slightly contributes to the better cell performance than the water solvent dye because of the better oxidation potential stabilization in the ground state as well as in the excited state. These results are in good agreement with the known experimental report that the aglycones of anthocyanidin dyes in basic solvent are the high potential photosensitizers for dye-sensitized solar cell.
Stationary flow of non-Newtonian fluid with nonmonotone frictional boundary conditions
NASA Astrophysics Data System (ADS)
Dudek, Sylwia; Kalita, Piotr; Migórski, Stanisław
2015-10-01
We study the stationary two-dimensional incompressible flow of non-Newtonian fluid governed by a nonlinear constitutive law and with a multivalued nonmonotone subdifferential frictional boundary condition. We provide an abstract result on existence of solution to an operator inclusion modeling the flow phenomenon. We prove a theorem on existence and, under additional assumptions, also uniqueness of weak solution to the flow problem.
NASA Astrophysics Data System (ADS)
Gromnitskaya, E. L.; Danilov, I. V.; Lyapin, A. G.; Brazhkin, V. V.
2015-10-01
We present a low-temperature and high-pressure ultrasonic study of elastic properties of isotopic H2O-D2O solid solutions, comparing their properties with those of the isotopically pure H2O and D2O ices. Measurements were carried out for solid state amorphization (SSA) from 1h to high-density amorphous (HDA) ice upon compression up to 1.8 GPa at 77 K and for the temperature-induced (77 -190 K ) u-HDA (unrelaxed HDA) → e-HDA (expanded HDA) → low-density amorphous (LDA )→1 c cascade of ice transformations near room pressure. There are many similarities in the elasticity behaviour of H2O ,D2O , and H2O-D2O solid solutions, including the softening of the shear elastic modulus as a precursor of SSA and the HDA →LDA transition. We have found significant isotopic effects during H/D substitution, including elastic softening of H2O -D2O solid solutions with respect to the isotopically pure ices in the case of the bulk moduli of ices 1c and 1h and for both bulk and shear elastic moduli of HDA ice at high pressures (>1 GPa ) . This softening is related to the configurational isotopic disorder in the solid solutions. At low pressures, the isotope concentration dependence of the elastic moduli of u-HDA ice changes remarkably and becomes monotonic with pronounced change of the bulk modulus (≈20 %) .
Uniqueness of a solution of a steady state photochemical problem: Applications to Mars
NASA Technical Reports Server (NTRS)
Krasnopolsky, Vladimir A.
1995-01-01
Based on the conservation of chemical elements in chemical reactions, a rule is proved that the number of boundary conditions given by densities and/or nonzero velocities should not be less than the number of chemical elements in the system, and the boundary conditions for species given by densities and velocities should include all elements in the system. Applications of this rule to Mars are considered. It is shown that the problem of the CO2-H2O chemistry in the lower and middle atmosphere of Mars, say, in the range of 0-80 km does not have a unique solution, if only CO2 and H2O densities are given at the lower boundary, and the remaining boundary conditions are fluxes. Two examples of models of this type are discussed. Two models of the photochemistry of the Martian atmosphere, with and without nitrogen chemistry, are considered. The oxygen nonthermal escape ratio of 1.2 x 10(exp 8)/cu cm/s is given at 240 km and is balanced with the total hydrogen escape rate within an uncertainty of 1% for both models. Both models fit the measured O2 and CO mixing ratios, the O3 abundance, and the O2 1.27-micrometer dayglow almost within the uncertainties of the measured values, though the model without nitrogen chemistry fits better. The importance of nitrogen chemistry in the lower and middle atmosphere of Mars depends on a fine balance between production of NO and N in the upper atmosphere which is not known within the required accuracy.
Structures of the 2-nitrophenol alkali complexes in solution and the solid state
NASA Astrophysics Data System (ADS)
Reichelt, Hendrik; Faunce, Chester A.; Paradies, Henrich H.
2015-07-01
The materials studied in this investigation were aqueous solutions (0.02-25.0 mM) of the salts of alkali metal ion (Me+) and 2-nitrophenol (2-NP). In the investigation, small-angle X-ray scattering, wide-angle X-ray scattering, and membrane-pressure osmometry were used to study the 2-NP-Me+ molecular salt structures and the onset of crystallization as a function of concentration and temperature. The experimental methods used to examine the 2-NP-Me+ molecular salt complexes provided corroborative evidence for the existence of spherical clusters with hydrodynamic diameters between ˜12 Å (Li) and 14 Å (Cs). Guinier plots of the zero-angle scattering peak were characteristic of the scattering from lamellae-like shapes with thicknesses of ˜290 Å. Tetramer and pentamer 2-NP-Me+ molecular clusters for Me+ = Li, Na, K, and Rb were assembled from four or five 2-NP molecules bound to a central alkali metal ion. The coordination symmetry around the six coordinated Li+, Na+, and K+ ions was that of a trigonal prism (D3h), with an octahedral arrangement (D2h). The Rb+ also revealed six-coordinate geometry and the central Rb+ ion adopted an octahedral arrangement (D2h). The eight-coordinated Cs+ ions with six 2-NP ligands were characteristic of a square antiprism (D4d). The square antiprism was the outcome of leaving two o-nitro groups and two phenolic oxygens being left intermolecularly uncoordinated to the Cs+ ion. The 2-NP residues were strictly planar and contained short non-bonded intramolecular distances. van der Waals forces were present between the adjacently stacked phenyl rings. No water molecules were involved as ligands for any of the 2-nitrophenol-Me+ complexes.
Gillilan, Richard E; Kumar, V S Senthil; O'Neall-Hennessey, Elizabeth; Cohen, Carolyn; Brown, Jerry H
2013-01-01
The overall conformations of regulated myosins or heavy meromyosins from chicken/turkey, scallop, tarantula, limulus, and scorpion sources have been studied by a number of techniques, including electron microscopy, sedimentation, and pulsed electron paramagnetic resonance. These studies have indicated that the binding of regulatory ions changes the conformation of the molecule from a compact shape found in the "off" state of the muscle to extended relationships between the tail and independently mobile heads that predominate in the "on" state. Here we strengthen the argument for the generality of this conformational change by using small angle X-ray scattering on heavy meromyosin from squid. Small angle X-ray scattering allows the protein to be visualized in solution under mild and relatively physiological conditions, and squid differs from the other species studied by at least 500 million years of evolution. Analysis of the data indicates that upon addition of Ca(2+) the radius of gyration increases. Differences in the squid "on" and "off" states are clearly distinguishable as bimodal and unimodal pair distance distribution functions respectively. These observations are consistent with a Ca(2+)-free squid heavy meromyosin that is compact, but which becomes extended when Ca(2+) is bound. Further, the scattering profile derived from the current model of tarantula heavy meromyosin in the "off" state is in excellent agreement with the measured "off" state scattering profile for squid heavy meromyosin. The previous and current studies together provide significant evidence that regulated myosin's compact off-state conformation is an ancient trait, inherited from a common ancestor during divergent evolution. PMID:24358137
Sancho, Matias I; Russo, Marcos G; Moreno, M Sergio; Gasull, Estela; Blanco, Sonia E; Narda, Griselda E
2015-05-01
The characterization of the inclusion complex between 2-hydroxybenzophenone (2OHBP) and β-cyclodextrin (βCD) in the solid state was performed using Fourier transform infrared spectroscopy (FTIR), powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The apparent formation constant of the complex was determined by phase solubility diagrams and liquid chromatography (HPLC) at different temperatures. The formation of the inclusion complex induced slight shifts in the FTIR spectrum while by PXRD a new crystalline phase was observed. TEM studies revealed that the complex forms aggregates of nanometric size. The inclusion complex showed a higher solubility in the tested dissolution media than free 2OHBP. Moreover, the freeze-dried solid complex exhibits a higher thermal stability than the solid free drug. The thermodynamic analysis allowed us to conclude that the encapsulation process is endothermic in water and exothermic in methanol-water. PMID:25893377
Solution of the two-mode quantum Rabi model using extended squeezed states
NASA Astrophysics Data System (ADS)
Duan, Liwei; He, Shu; Braak, Daniel; Chen, Qing-Hu
2015-11-01
The two-mode quantum Rabi model with bilinear coupling is studied using extended squeezed states. We derive G-functions for each Bargmann index q. They share a common structure with the G-function of the one-photon and two-photon quantum Rabi models. The regular spectrum is given by zeros of the G-function while the conditions for the presence of doubly degenerate (exceptional) eigenvalues are obtained in closed form through the lifting property. The simple singularity structure of the G-function allows to draw conclusions about the distribution of eigenvalues along the real axis and to understand the spectral collapse phenomenon when the coupling reaches a critical value.
Finite Element Solution of the Steady-State Smoluchowski Equation for Rate Constant Calculations
Song, Yuhua; Zhang, Yongjie; Shen, Tongye; Bajaj, Chandrajit L.; McCammon, J. Andrew; Baker, Nathan A.
2004-01-01
This article describes the development and implementation of algorithms to study diffusion in biomolecular systems using continuum mechanics equations. Specifically, finite element methods have been developed to solve the steady-state Smoluchowski equation to calculate ligand binding rate constants for large biomolecules. The resulting software has been validated and applied to mouse acetylcholinesterase. Rates for inhibitor binding to mAChE were calculated at various ionic strengths with several different reaction criteria. The calculated rates were compared with experimental data and show very good agreement when the correct reaction criterion is used. Additionally, these finite element methods require significantly less computational resources than existing particle-based Brownian dynamics methods. PMID:15041644
Ultrafast dynamics of excited state of phenoxy-phthalocyanines in solution
NASA Astrophysics Data System (ADS)
Yao, Cheng-Bao; Yan, Xiao-Yan; Sun, Da-Wei; Sui, Yan-Li; Li, Jin; Sun, Wen-Jun; Li, Qiang-Hua; Yang, Shou-Bin
2016-01-01
Ultrafast dynamics of the excited state of 2,9,16,23-phenoxy-phthalocyanine (Pc1) and 2,9,16,23-phenoxy-phthalocyanine-zinc (Pc2) has been investigated using femtosecond transient absorption (TA) and time-resolved fluorescence (TRFL) techniques. The observed dynamics of femtosecond TA and TRFL experiments are similar, which demonstrated the intrinsic properties of the excitation and the relaxation processes in both kinds of phthalocyanines with two decay components. A multi level model has been proposed to explain the photophysical processes after Soret-band excitation. The results show that the fast decay component dynamics comes from the intramolecular vibrational relaxation, the slower ones from the internal conversion. The samples are expected to be a potential candidate for optical applications and photodynamic therapy.
Solution of two-body relativistic bound state equations with confining plus Coulomb interactions
NASA Technical Reports Server (NTRS)
Maung, Khin Maung; Kahana, David E.; Norbury, John W.
1992-01-01
Studies of meson spectroscopy have often employed a nonrelativistic Coulomb plus Linear Confining potential in position space. However, because the quarks in mesons move at an appreciable fraction of the speed of light, it is necessary to use a relativistic treatment of the bound state problem. Such a treatment is most easily carried out in momentum space. However, the position space Linear and Coulomb potentials lead to singular kernels in momentum space. Using a subtraction procedure we show how to remove these singularities exactly and thereby solve the Schroedinger equation in momentum space for all partial waves. Furthermore, we generalize the Linear and Coulomb potentials to relativistic kernels in four dimensional momentum space. Again we use a subtraction procedure to remove the relativistic singularities exactly for all partial waves. This enables us to solve three dimensional reductions of the Bethe-Salpeter equation. We solve six such equations for Coulomb plus Confining interactions for all partial waves.
Non-stationary (13)C-metabolic flux ratio analysis.
Hörl, Manuel; Schnidder, Julian; Sauer, Uwe; Zamboni, Nicola
2013-12-01
(13)C-metabolic flux analysis ((13)C-MFA) has become a key method for metabolic engineering and systems biology. In the most common methodology, fluxes are calculated by global isotopomer balancing and iterative fitting to stationary (13)C-labeling data. This approach requires a closed carbon balance, long-lasting metabolic steady state, and the detection of (13)C-patterns in a large number of metabolites. These restrictions mostly reduced the application of (13)C-MFA to the central carbon metabolism of well-studied model organisms grown in minimal media with a single carbon source. Here we introduce non-stationary (13)C-metabolic flux ratio analysis as a novel method for (13)C-MFA to allow estimating local, relative fluxes from ultra-short (13)C-labeling experiments and without the need for global isotopomer balancing. The approach relies on the acquisition of non-stationary (13)C-labeling data exclusively for metabolites in the proximity of a node of converging fluxes and a local parameter estimation with a system of ordinary differential equations. We developed a generalized workflow that takes into account reaction types and the availability of mass spectrometric data on molecular ions or fragments for data processing, modeling, parameter and error estimation. We demonstrated the approach by analyzing three key nodes of converging fluxes in central metabolism of Bacillus subtilis. We obtained flux estimates that are in agreement with published results obtained from steady state experiments, but reduced the duration of the necessary (13)C-labeling experiment to less than a minute. These results show that our strategy enables to formally estimate relative pathway fluxes on extremely short time scale, neglecting cellular carbon balancing. Hence this approach paves the road to targeted (13)C-MFA in dynamic systems with multiple carbon sources and towards rich media. PMID:23860906
Evaluation of an amide-based stationary phase for supercritical fluid chromatography.
Borges-Muñoz, Amaris C; Colón, Luis A
2016-09-01
J. Sep. Sci. 2016, 39, 3469-3476 A stationary phase containing an amide group embedded in a hydrophobic backbone (i.e., C18-amide) attached to silica particles was characterized by means of the linear solvation energy relationship model, which relates the chromatographic retention factor to specific solute interactions. The evaluationwas conducted under supercritical fluid chromatographic conditions using a mobile phase composition of carbon dioxide and methanol as co-solvent. The stationary phase showed to provide an alternate separation selectivity that is attractive to separate drug-like polar compounds in a relatively fast analysis time. PMID:27598573
Stationary plasma thruster evaluation in Russia
NASA Technical Reports Server (NTRS)
Brophy, John R.
1992-01-01
A team of electric propulsion specialists from U.S. government laboratories experimentally evaluated the performance of a 1.35-kW Stationary Plasma Thruster (SPT) at the Scientific Research Institute of Thermal Processes in Moscow and at 'Fakel' Enterprise in Kaliningrad, Russia. The evaluation was performed using a combination of U.S. and Russian instrumentation and indicated that the actual performance of the thruster appears to be close to the claimed performance. The claimed performance was a specific impulse of 16,000 m/s, an overall efficiency of 50 percent, and an input power of 1.35 kW, and is superior to the performance of western electric thrusters at this specific impulse. The unique performance capabilities of the stationary plasma thruster, along with claims that more than fifty of the 660-W thrusters have been flown in space on Russian spacecraft, attracted the interest of western spacecraft propulsion specialists. A two-phase program was initiated to evaluate the stationary plasma thruster performance and technology. The first phase of this program, to experimentally evaluate the performance of the thruster with U.S. instrumentation in Russia, is described in this report. The second phase objective is to determine the suitability of the stationary plasma thruster technology for use on western spacecraft. This will be accomplished by bringing stationary plasma thrusters to the U.S. for quantification of thruster erosion rates, measurements of the performance variation as a function of long-duration operation, quantification of the exhaust beam divergence angle, and determination of the non-propellant efflux from the thruster. These issues require quantification in order to maximize the probability for user application of the SPT technology and significantly increase the propulsion capabilities of U.S. spacecraft.
Not Available
1980-08-01
The Conceptual Design is described of Stirling Engines for Stationary Power Application in the 500 to 3000 hp range which was aimed at state-of-the-art stationary Stirling engines for a 1985 hardware demonstration, and an advanced engine design with identification of the supporting R and D efforts required. The main goals of this effort were to obtain reliable cost data for a stationary Stirling engine capable of meeting future needs for total energy/cogeneration systems and to establish a pragmatic and conservative base design for a first-generation hardware. In order to secure a competitive position for this engine in the marketplace, it was clearly recognized that a coal and waste product fired version had to be given primary consideration since a fuel oil or gas fired version would not be cost competitive with a diesel/gas engine. Therefore, the mating of the Stirling engine with an Atmospheric Fluidized Bed (AFB) was a main target.
Stationary three-dimensional entanglement via dissipative Rydberg pumping
NASA Astrophysics Data System (ADS)
Shao, Xiao-Qiang; You, Jia-Bin; Zheng, Tai-Yu; Oh, C. H.; Zhang, Shou
2014-05-01
We extend the recent result of a bipartite Bell singlet [A. W. Carr and M. Saffman, Phys. Rev. Lett. 111, 033607 (2013), 10.1103/PhysRevLett.111.033607] to a stationary three-dimensional entanglement between two-individual neutral Rydberg atoms. This proposal makes full use of the coherent dynamics provided by a Rydberg-mediated interaction and the dissipative factor originating from the spontaneous emission of a Rydberg state. The numerical simulation of the master equation reveals that both the target state negativity N (ρ̂∞) and fidelity F (ρ̂∞) can exceed 99.90%. Furthermore, a steady three-atom singlet state |S3> is also achievable based on the same mechanism.
Kuznetsova, Irina M; Povarova, Olga I; Uversky, Vladimir N; Turoverov, Konstantin K
2016-02-01
The native form of globular actin, G-actin, is formed in vivo as a result of complex post-translational folding processes that require ATP energy expenditure and are assisted by the 70 kDa heat shock protein, prefoldin and chaperonin containing TCP-1. G-actin is stabilized by the binding of one ATP molecule and one Ca(2+) ion (or Mg(2+) in vivo). Chemical denaturants, heating or Ca(2+) removal transform native actin (N) into 'inactivated actin' (I), a compact oligomer comprising 14-16 subunits. Viscogenic and crowding agents slow this process but do not stop it. The lack of calcium in the solution accelerates the spontaneous N → I transition. Thus, native G-actin has a kinetically stable (as a result of the high free energy barrier between the N and I states) but thermodynamically unstable structure, which, in the absence of Ca(2+) or other bivalent metal ions, spontaneously converts to the thermodynamically stable I state. It was noted that native actin has much in common with intrinsically disordered proteins: it has functionally important disordered regions; it is constantly in complex with one of its numerous partners; and it plays key roles in many cellular processes, in a manner similar to disordered hub proteins. By analyzing actin folding in vivo and unfolding in vitro, we advanced the hypothesis that proteins in a native state may have a thermodynamically unstable quasi-stationary structure. The kinetically stable native state of these proteins appears forcibly under the influence of intracellular folding machinery. The denaturation of such proteins is always irreversible because the inactivated state, for which the structure is determined by the amino acid sequence of a protein, comprises the thermodynamically stable state under physiological conditions. PMID:26460158
Kobayashi, Hirokazu; Kusada, Kohei; Kitagawa, Hiroshi
2015-06-16
Currently 118 known elements are represented in the periodic table. Of these 118 elements, only about 80 elements are stable, nonradioactive, and widely available for our society. From the viewpoint of the "elements strategy", we need to make full use of the 80 elements to bring out their latent ability and create innovative materials. Furthermore, there is a strong demand that the use of rare or toxic elements be reduced or replaced while their important properties are retained. Advanced science and technology could create higher-performance materials even while replacing or reducing minor or harmful elements through the combination of more abundant elements. The properties of elements are correlated directly with their electronic states. In a solid, the magnitude of the density of states (DOS) at the Fermi level affects the physical and chemical properties. In the present age, more attention has been paid to improving the properties of materials by means of alloying elements. In particular, the solid-solution-type alloy is advantageous because the properties can be continuously controlled by tuning the compositions and/or combinations of the constituent elements. However, the majority of bulk alloys are of the phase-separated type under ambient conditions, where constituent elements are immiscible with each other. To overcome the challenge of the bulk-phase metallurgical aspects, we have focused on the nanosize effect and developed methods involving "nonequilibrium synthesis" or "a process of hydrogen absorption/desorption". We propose a new concept of "density-of-states engineering" for the design of materials having the most desirable and suitable properties by means of "interelement fusion". In this Account, we describe novel solid-solution alloys of Pd-Pt, Ag-Rh, and Pd-Ru systems in which the constituent elements are immiscible in the bulk state. The homogeneous solid-solution alloys of Pd and Pt were created from Pd core/Pt shell nanoparticles using a
Stabilization of high-order solutions of the cubic nonlinear Schroedinger equation
Alexandrescu, Adrian; Montesinos, Gaspar D.; Perez-Garcia, Victor M.
2007-04-15
In this paper we consider the stabilization of nonfundamental unstable stationary solutions of the cubic nonlinear Schroedinger equation. Specifically, we study the stabilization of radially symmetric solutions with nodes and asymmetric complex stationary solutions. For the first ones, we find partial stabilization similar to that recently found for vortex solutions while for the later ones stabilization does not seem possible.
Stationary bubbles and their tunneling channels toward trivial geometry
Chen, Pisin; Domènech, Guillem; Sasaki, Misao; Yeom, Dong-han
2016-04-07
In the path integral approach, one has to sum over all histories that start from the same initial condition in order to obtain the final condition as a superposition of histories. Applying this into black hole dynamics, we consider stable and unstable stationary bubbles as a reasonable and regular initial condition. We find examples where the bubble can either form a black hole or tunnel toward a trivial geometry, i.e., with no singularity nor event horizon. We investigate the dynamics and tunneling channels of true vacuum bubbles for various tensions. In particular, in line with the idea of superposition ofmore » geometries, we build a classically stable stationary thin-shell solution in a Minkowski background where its fate is probabilistically given by non-perturbative effects. Since there exists a tunneling channel toward a trivial geometry in the entire path integral, the entire information is encoded in the wave function. This demonstrates that the unitarity is preserved and there is no loss of information when viewed from the entire wave function of the universe, whereas a semi-classical observer, who can see only a definitive geometry, would find an effective loss of information. Ultimately, this may provide a resolution to the information loss dilemma.« less
Stationary bubbles and their tunneling channels toward trivial geometry
NASA Astrophysics Data System (ADS)
Chen, Pisin; Domènech, Guillem; Sasaki, Misao; Yeom, Dong-han
2016-04-01
In the path integral approach, one has to sum over all histories that start from the same initial condition in order to obtain the final condition as a superposition of histories. Applying this into black hole dynamics, we consider stable and unstable stationary bubbles as a reasonable and regular initial condition. We find examples where the bubble can either form a black hole or tunnel toward a trivial geometry, i.e., with no singularity nor event horizon. We investigate the dynamics and tunneling channels of true vacuum bubbles for various tensions. In particular, in line with the idea of superposition of geometries, we build a classically stable stationary thin-shell solution in a Minkowski background where its fate is probabilistically given by non-perturbative effects. Since there exists a tunneling channel toward a trivial geometry in the entire path integral, the entire information is encoded in the wave function. This demonstrates that the unitarity is preserved and there is no loss of information when viewed from the entire wave function of the universe, whereas a semi-classical observer, who can see only a definitive geometry, would find an effective loss of information. This may provide a resolution to the information loss dilemma.
Sampling and analysis information aids for stationary source personnel
Jackson, M.D.; Johnson, L.D.
1994-12-31
The Environmental Protection Agency, in developing and evaluating samples and analysis methodology for stationary sources, has compiled information on availability and applicability of sampling and analytical methods. Information has also been summarized on the applicability of the gas chromatography/mass spectrometry as the analytical method. All of this information is accessible in three documents: ``Stationary Source Sampling and Analysis Directory, Version 2`` (SSSADIR), ``Handbook of GC/MS Data and Information for Selected Clean Air Act Amendments Compounds`` (Handbook), and ``Literature Review of CAAA Compounds`` (LitRev). The SSSADIR has information on which sampling and analytical methods to use for organic compounds listed in Title 3 of the Clean Air Act Amendments (CAAA) of 1990, as well as Appendices 8 and 9 of RCRA compounds, and the status of method evaluation for these analytes. The Handbook provides information on the mass spectra of selected CAAA analytes, primary quantitation ions, relative retention times and compatibility of the organic compounds in solution. The LitRev provides information on CAAA compounds for which EPA has no potential methods available but provides suggestions on ways to develop methods.
Constraints on the effective fluid theory of stationary branes
NASA Astrophysics Data System (ADS)
Armas, Jay; Harmark, Troels
2014-10-01
We develop further the effective fluid theory of stationary branes. This formalism applies to stationary blackfolds as well as to other equilibrium brane systems at finite temperature. The effective theory is described by a Lagrangian containing the information about the elastic dynamics of the brane embedding as well as the hydrodynamics of the effective fluid living on the brane. The Lagrangian is corrected order-by-order in a derivative expansion, where we take into account the dipole moment of the brane which encompasses finite-thickness corrections, including transverse spin. We describe how to extract the thermodynamics from the Lagrangian and we obtain constraints on the higher-derivative terms with one and two derivatives. These constraints follow by comparing the brane thermodynamics with the conserved currents associated with background Killing vector fields. In particular, we fix uniquely the one- and two-derivative terms describing the coupling of the transverse spin to the background space-time. Finally, we apply our formalism to two blackfold examples, the black tori and charged black rings and compare the latter to a numerically generated solution.
EDITORIAL: CAMOP: Quantum Non-Stationary Systems CAMOP: Quantum Non-Stationary Systems
NASA Astrophysics Data System (ADS)
Dodonov, Victor V.; Man'ko, Margarita A.
2010-09-01
Although time-dependent quantum systems have been studied since the very beginning of quantum mechanics, they continue to attract the attention of many researchers, and almost every decade new important discoveries or new fields of application are made. Among the impressive results or by-products of these studies, one should note the discovery of the path integral method in the 1940s, coherent and squeezed states in the 1960-70s, quantum tunneling in Josephson contacts and SQUIDs in the 1960s, the theory of time-dependent quantum invariants in the 1960-70s, different forms of quantum master equations in the 1960-70s, the Zeno effect in the 1970s, the concept of geometric phase in the 1980s, decoherence of macroscopic superpositions in the 1980s, quantum non-demolition measurements in the 1980s, dynamics of particles in quantum traps and cavity QED in the 1980-90s, and time-dependent processes in mesoscopic quantum devices in the 1990s. All these topics continue to be the subject of many publications. Now we are witnessing a new wave of interest in quantum non-stationary systems in different areas, from cosmology (the very first moments of the Universe) and quantum field theory (particle pair creation in ultra-strong fields) to elementary particle physics (neutrino oscillations). A rapid increase in the number of theoretical and experimental works on time-dependent phenomena is also observed in quantum optics, quantum information theory and condensed matter physics. Time-dependent tunneling and time-dependent transport in nano-structures are examples of such phenomena. Another emerging direction of study, stimulated by impressive progress in experimental techniques, is related to attempts to observe the quantum behavior of macroscopic objects, such as mirrors interacting with quantum fields in nano-resonators. Quantum effects manifest themselves in the dynamics of nano-electromechanical systems; they are dominant in the quite new and very promising field of circuit
NASA Astrophysics Data System (ADS)
Horváth, Judit; Szalai, István; De Kepper, Patrick
2010-06-01
We present a detailed study of the reaction-diffusion patterns observed in the thiourea-iodate-sulfite (TuIS) reaction, operated in open one-side-fed reactors. Besides spatial bistability and spatio-temporal oscillatory dynamics, this proton autoactivated reaction shows stationary patterns, as a result of two back-to-back Turing bifurcations, in the presence of a low-mobility proton binding agent (sodium polyacrylate). This is the third aqueous solution system to produce stationary patterns and the second to do this through a Turing bifurcation. The stationary pattern forming capacities of the reaction are explored through a systematic design method, which is applicable to other bistable and oscillatory reactions. The spatio-temporal dynamics of this reaction is compared with that of the previous ferrocyanide-iodate-sulfite mixed Landolt system.
An alternative numerical method for the stationary pulsar magnetosphere
NASA Astrophysics Data System (ADS)
Takamori, Yohsuke; Okawa, Hirotada; Takamoto, Makoto; Suwa, Yudai
2014-02-01
Stationary pulsar magnetospheres in the force-free system are governed by the pulsar equation. In 1999, Contopoulos, Kazanas, and Fendt (hereafter CKF) numerically solved the pulsar equation and obtained a pulsar magnetosphere model called the CKF solution that has both closed and open magnetic field lines. The CKF solution is a successful solution, but it contains a poloidal current sheet that flows along the last open field line. This current sheet is artificially added to make the current system closed. In this paper, we suggest an alternative method to solve the pulsar equation and construct pulsar magnetosphere models without a current sheet. In our method, the pulsar equation is decomposed into Ampère's law and the force-free condition. We numerically solve these equations simultaneously with a fixed poloidal current. As a result, we obtain a pulsar magnetosphere model without a current sheet, which is similar to the CKF solution near the neutron star and has a jet-like structure at a distance along the pole. In addition, we discuss physical properties of the model and find that the force-free condition breaks down in a vicinity of the light cylinder due to dissipation that is included implicitly in the numerical method.
Kinetic vortex chain solution in the drift-wave plasma regime
Jovanovic; Pegoraro
2000-01-01
A fully nonlinear Bernstein-Greene-Kruskal stationary solution is found in the form of a quasi-three-dimensional chain of electron holes coupled to hydrodynamic vortices. This new coherent structure is enabled by the trapping and depletion of resonant particles, and the cyclotron dissipation of the singular current sheets. It is expected to play an important role in the collisionless magnetic field line reconnection in the drift-wave plasma regime, where it represents a plausible saturated state. PMID:11015843
Survival guide: Escherichia coli in the stationary phase
Pletnev, P.; Osterman, I.; Sergiev, P.; Bogdanov, A.; Dontsova, O.
2015-01-01
This review centers on the stationary phase of bacterial culture. The basic processes specific to the stationary phase, as well as the regulatory mechanisms that allow the bacteria to survive in conditions of stress, are described. PMID:26798489