NASA Technical Reports Server (NTRS)
Kleinman, D. L.
1976-01-01
A numerical technique is given for solving the matrix quadratic equation that arises in the optimal stationary control of linear systems with state (and/or control) dependent noise. The technique exploits fully existing, efficient algorithms for the matrix Lyapunov and Ricatti equations. The computational requirements are discussed, with an associated example.
Nonequilibrium stationary states and entropy.
Gallavotti, G; Cohen, E G D
2004-03-01
In transformations between nonequilibrium stationary states, entropy might not be a well defined concept. It might be analogous to the "heat content" in transformations in equilibrium which is not well defined either, if they are not isochoric (i.e., do involve mechanical work). Hence we conjecture that in a nonequilibrium stationary state the entropy is just a quantity that can be transferred or created, such as heat in equilibrium, but has no physical meaning as "entropy content" as a property of the system.
Multiple stationary solutions of an irradiated slab
NASA Astrophysics Data System (ADS)
Taylor, P. D.; Feltham, D. L.
2005-04-01
A mathematical model describing the heat budget of an irradiated medium is introduced. The one-dimensional form of the equations and boundary conditions are presented and analysed. Heat transport at one face of the slab occurs by absorption (and reflection) of an incoming beam of short-wave radiation with a fraction of this radiation penetrating into the body of the slab, a diffusive heat flux in the slab and a prescribed incoming heat flux term. The other face of the slab is immersed in its own melt and is considered to be a free surface. Here, temperature continuity is prescribed and evolution of the surface is determined by a Stefan condition. These boundary conditions are flexible enough to describe a range of situations such as a laser shining on an opaque medium, or the natural environment of polar sea ice or lake ice. A two-stream radiation model is used which replaces the simple Beer's law of radiation attenuation frequently used for semi-infinite domains. The stationary solutions of the governing equations are sought and it is found that there exists two possible stationary solutions for a given set of boundary conditions and a range of parameter choices. It is found that the existence of two stationary solutions is a direct result of the model of radiation absorption, due to its effect on the albedo of the medium. A linear stability analysis and numerical calculations indicate that where two stationary solutions exist, the solution corresponding to a larger thickness is always stable and the solution corresponding to a smaller thickness is unstable. Numerical simulations reveal that when there are two solutions, if the slab is thinner than the smaller stationary thickness it will melt completely, whereas if the slab is thicker than the smaller stationary thickness it will evolve toward the larger stationary thickness. These results indicate that other mechanisms (e.g. wave-induced agglomeration of crystals) are necessary to grow a slab from zero initial
Poissonian steady states: from stationary densities to stationary intensities.
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.
The problem on stationary states in self gravitational field
NASA Astrophysics Data System (ADS)
Fisenko, Stanislav
2017-01-01
To follow is the problem on stationary states of an electron in its own gravitational field where the boundary conditions earlier described by are made specific. The simplest approximation provides an assessment of the energy spectrum of stationary states only. Nevertheless, this is enough to confirm the existence of such stationary states and to further elaborate a detailed solution of the problem on stationary states including determination of all the quantum numbers' spectra and corresponding wave functions. No other matters are discussed here. The case in hand is a purely mathematical problem, further physical interpretation of which is of a fundamental value.
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.
On Stationary States in the Double Phosphorylation-dephosphorylation Cycle
NASA Astrophysics Data System (ADS)
Bersani, Alberto Maria; Dell'Acqua, Guido; Tomassetti, Giovanna
2011-09-01
In this paper we study the double phosphorylation-dephosphorylation cycle, which is a special case of multiple futile cycle. We study the stationary states, finding some classes of explicit solutions.
Universal BPS structure of stationary supergravity solutions
NASA Astrophysics Data System (ADS)
Bossard, Guillaume; Nicolai, Hermann; Stelle, K. S.
2009-07-01
We study asymptotically flat stationary solutions of four-dimensional supergravity theories via the associated fraktur G/fraktur H* pseudo-Riemannian non-linear sigma models in three spatial dimensions. The Noether charge Script C associated to fraktur G is shown to satisfy a characteristic equation that determines it as a function of the four-dimensional conserved charges. The matrix Script C is nilpotent for non-rotating extremal solutions. The nilpotency degree of Script C is directly related to the BPS degree of the corresponding solution when they are BPS. Equivalently, the charges can be described in terms of a Weyl spinor |Script Crangle of Spin*(2Script N), and then the characteristic equation becomes equivalent to a generalisation of the Cartan pure spinor constraint on |Script Crangle. The invariance of a given solution with respect to supersymmetry is determined by an algebraic `Dirac equation' on the Weyl spinor |Script Crangle. We explicitly solve this equation for all pure supergravity theories and we characterise the stratified structure of the moduli space of asymptotically Taub-NUT black holes with respect to their BPS degree. The analysis is valid for any asymptotically flat stationary solutions for which the singularities are protected by horizons. The fraktur H*-orbits of extremal solutions are identified as Lagrangian submanifolds of nilpotent orbits of fraktur G, and so the moduli space of extremal spherically symmetric black holes is identified as a Lagrangian subvariety of the variety of nilpotent elements of fraktur g. We also generalise the notion of active duality transformations to an `almost action' of the three-dimensional duality group fraktur G on asymptotically flat stationary solutions.
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
2015-11-20
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."
Exact Stationary and Non-stationary Solutions to Inelastic Maxwell Model with Infinite Energy
NASA Astrophysics Data System (ADS)
Ilyin, Oleg
2016-11-01
The one-dimensional inelastic Boltzmann equation with a constant collision rate (the Maxwell model) is considered. It is shown that for special values of restitution parameter there exists a stationary solution with the characteristic function in the form e^{-P(log (z))z}, where P is a periodic function. The corresponding distribution function belongs to a one special class of stochastic processes termed as a generalized stable in the probability theory. The Fourier transform of the non-stationary equation has the solution bigl (1+P(log (z))zbigr )e^{-Q(log (z))z}. It is proved that this solution is a characteristic function if periodic functions P, Q satisfy some not very restrictive conditions. The stationary and non-stationary solutions correspond to a gas with infinite temperature.
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.
Stationary solutions for conservation laws with singular nonlocal sources
NASA Astrophysics Data System (ADS)
Coclite, Giuseppe Maria; Coclite, Mario Michele
The existence of an a.e. positive stationary solution with bounded variation in [0,1] for an integro-differential conservation law with source depending on a function singular in the origin is proved.
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.
Nucleoid restructuring in stationary-state bacteria.
Frenkiel-Krispin, Daphna; Ben-Avraham, Irit; Englander, Joseph; Shimoni, Eyal; Wolf, Sharon G; Minsky, Abraham
2004-01-01
The textbook view of the bacterial cytoplasm as an unstructured environment has been overturned recently by studies that highlighted the extent to which non-random organization and coherent motion of intracellular components are central for bacterial life-sustaining activities. Because such a dynamic order critically depends on continuous consumption of energy, it cannot be perpetuated in starved, and hence energy-depleted, stationary-state bacteria. Here, we show that, at the onset of the stationary state, bacterial chromatin undergoes a massive reorganization into ordered toroidal structures through a process that is dictated by the intrinsic properties of DNA and by the ubiquitous starvation-induced DNA-binding protein Dps. As starvation proceeds, the toroidal morphology acts as a structural template that promotes the formation of DNA-Dps crystalline assemblies through epitaxial growth. Within the resulting condensed assemblies, DNA is effectively protected by means of structural sequestration. We thus conclude that the transition from bacterial active growth to stationary phase entails a co-ordinated process, in which the energy-dependent dynamic order of the chromatin is sequentially substituted with an equilibrium crystalline order.
NASA Astrophysics Data System (ADS)
Horvath, I.; Lukacs, B.
The stationary vacuum solutions of the Einstein equations of general relativity give the external space-time around stationary mass distributions, as e.g. final states of stellar evolution. The Kerr solution has shear-free geodesic eigenrays and describes all black hole configurations with good asymptotic behaviour at infinity. Other solutions of this class are unphysical. Classes with shearing geodesic or shearfree nongeodesic eigenrays do not contain physical solutions at all, so for other physical configurations one must turn to the generic case of shearing nongeodesic eigenrays. For the stationary axisymmetric case Ansaetze for solutions can be formulated in form of a specific functional dependence between the parameters of shear and nongeodesicity, unless they both are constants. Here the authors investigate the second subcase. Their result is that there is no solution of the vacuum Einstein equations in this subclass, except when both parameters vanish.
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.
Analyzing stationary states of gene regulatory network using petri nets.
Gambin, Anna; Lasota, Sławomir; Rutkowski, Michał
2006-01-01
We introduce and formally define the notion of a stationary state for Petri nets. We also propose a fully automatic method for finding such states. The procedure makes use of the Presburger arithmetic to describe all the stationary states. Finally we apply this novel approach to find stationary states of a gene regulatory network describing the flower morphogenesis of A. thaliana. This shows that the proposed method can be successfully applied in the study of biological systems.
Analyzing stationary States of gene regulatory network using petri nets.
Gambin, Anna; Lasota, Sławomir; Rutkowski, Michał
2011-01-01
We introduce and formally define the notion of a stationary state for Petri nets. We also propose a fully automatic method for finding such states. The procedure makes use of the Presburger arithmetic to describe all the stationary states. Finally we apply this novel approach to find stationary states of a gene regulatory network describing the flower morphogenesis of A. thaliana. This shows that the proposed method can be successfully applied in the study of biological systems.
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.
Exchangeable, stationary, and entangled chains of Gaussian states
NASA Astrophysics Data System (ADS)
Parthasarathy, K. R.; Sengupta, Ritabrata
2015-10-01
We explore conditions on the covariance matrices of a consistent chain of mean zero finite mode Gaussian states in order that the chain may be exchangeable or stationary. For an exchangeable chain, our conditions are necessary and sufficient. Every stationary Gaussian chain admits an asymptotic entropy rate. Whereas an exchangeable chain admits a simple expression for its entropy rate, in our examples of stationary chains, the same admits an integral formula based on the asymptotic eigenvalue distribution for Toeplitz matrices. An example of a stationary entangled Gaussian chain is given.
Stationary solutions in a model three-body problem
NASA Astrophysics Data System (ADS)
Zlenko, A. A.
2016-12-01
Two visco-elastic bodies (deformable spheres) are considered which interact with each other and move in quasi-circular orbits in the attractive force field of a fixed centre - a heavy point mass. Their axes of rotation are perpendicular to their orbital plane. Stationary solutions of the evolutionary equations of motion are found. In one particular case, they extend solutions of the restricted circular three-body problem corresponding to two collinear libration points. All three bodies are located along a straight line. This implies synchronization of motion of the barycentre of the two visco-elastic bodies relative to the attracting centre with their orbital motion relative to the barycentre in a 1:1 resonance. The rotation of the two bodies relative to their own centres of mass takes place in such a way that the bodies "view" the attracting centre and each other from the same side, i.e., they are synchronized in a 1:1 resonance with their orbital motion. Instability of stationary solutions is analytically proven.
On the Gross-Pitaevskii Equation with Pumping and Decay: Stationary States and Their Stability
NASA Astrophysics Data System (ADS)
Sierra, Jesús; Kasimov, Aslan; Markowich, Peter; Weishäupl, Rada-Maria
2015-06-01
We investigate the behavior of solutions of the complex Gross-Pitaevskii equation, a model that describes the dynamics of pumped decaying Bose-Einstein condensates. The stationary radially symmetric solutions of the equation are studied, and their linear stability with respect to two-dimensional perturbations is analyzed. Using numerical continuation, we calculate not only the ground state of the system, but also a number of excited states. Accurate numerical integration is employed to study the general nonlinear evolution of the system from the unstable stationary solutions to the formation of stable vortex patterns.
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.
Thermodynamical description of stationary, asymptotically flat solutions with conical singularities
NASA Astrophysics Data System (ADS)
Herdeiro, Carlos; Radu, Eugen; Rebelo, Carmen
2010-05-01
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. DPRVDAQ1550-7998 81, 064013 (2010).10.1103/PhysRevD.81.064013]. The examples considered are the double-Kerr solution, the black ring rotating in either S2 or S1, 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.
Macroscopic Fluctuation Theory for Stationary Non-Equilibrium States
NASA Astrophysics Data System (ADS)
Bertini, L.; de Sole, A.; Gabrielli, D.; Jona-Lasinio, G.; Landim, C.
2002-05-01
We formulate a dynamical fluctuation theory for stationary non-equilibrium states (SNS) which is tested explicitly in stochastic models of interacting particles. In our theory a crucial role is played by the time reversed dynamics. Within this theory we derive the following results: the modification of the Onsager-Machlup theory in the SNS; a general Hamilton-Jacobi equation for the macroscopic entropy; a non-equilibrium, nonlinear fluctuation dissipation relation valid for a wide class of systems; an H theorem for the entropy. We discuss in detail two models of stochastic boundary driven lattice gases: the zero range and the simple exclusion processes. In the first model the invariant measure is explicitly known and we verify the predictions of the general theory. For the one dimensional simple exclusion process, as recently shown by Derrida, Lebowitz, and Speer, it is possible to express the macroscopic entropy in terms of the solution of a nonlinear ordinary differential equation; by using the Hamilton-Jacobi equation, we obtain a logically independent derivation of this result.
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.
Maximum entropy principle for stationary states underpinned by stochastic thermodynamics
NASA Astrophysics Data System (ADS)
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.
Relaxation dynamics near nonequilibrium stationary states in Brownian ratchets
NASA Astrophysics Data System (ADS)
Woo, Hyung-June
2009-02-01
A comprehensive study of the static and dynamical properties of a representative stochastic model of Brownian ratchet effects for molecular motors is reported. The model describes Brownian motions on two periodic potentials under static and time-dependent forces, where there are two distinct locations of chemical reactions coupling the levels with reversible rates within a period. Complete stationary properties have been obtained analytically for arbitrary potentials under external force. Dynamical relaxation properties near nonequilibrium stationary states were examined by considering the response function of velocity upon time-dependent external force, expressed in terms of the conditional probability density of the model. The latter is fully calculated using a systematic numerical method using matrix diagonalization, which is easily generalized to more complicated models for studying both static and dynamical properties. The behavior of the time-dependent response examined for model potentials suggests that the characteristic relaxation time near stationary states generally decreases linearly with respect to increasing velocity as one goes away from equilibrium via an increase in chemical potential of fuel species, a prediction testable in single molecule experiments.
Stationary states and spatial patterning in an SIS epidemiology model with implicit mobility
NASA Astrophysics Data System (ADS)
Ilnytskyi, Jaroslav; Kozitsky, Yuri; Ilnytskyi, Hryhoriy; Haiduchok, Olena
2016-11-01
By means of the asynchronous cellular automata algorithm we study stationary states and spatial patterning in an SIS model, in which the individuals are attached to the vertices of a graph and their mobility is mimicked by varying the neighbourhood size q. Here we consider the following cases: q is fixed at certain value; and q is taken at random at each step and for each individual. The obtained numerical data are then mapped onto the solution of its version, corresponding to the limit q → ∞. This allows for deducing an explicit form of the dependence of the fraction of infected individuals on the curing rate γ. A detailed analysis of the appearance of spatial patterns of infected individuals in the stationary state is performed.
All stationary vacuum solutions with geodesic shearfree eigenrays.
NASA Astrophysics Data System (ADS)
Horvath, I.; Lukacs, B.; Szello, L.
1997-12-01
The Kerr solution, which is the general vacuum black hole solution in general relativity, belongs to the class of geodesic shearfree eigenrays, but it is somehow isolated within the class. For better orientation in future Kerr generalisation one would like to map completely the σ = κ = 0 class. Therefore in this paper the authors methodically look for all possible subclasses of solutions in the said class, and explicitly treat their connections with each other.
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.
NASA Astrophysics Data System (ADS)
Barré, Julien; Yamaguchi, Yoshiyuki Y.
2015-08-01
We consider the one-dimensional Vlasov equation with an attractive cosine potential, and its non-homogeneous stable stationary states that are decreasing functions of the energy. We show that in the Sobolev space W1,p (p > 2) neighborhood of such a state, all stationary states that are decreasing functions of the energy are stable. This is in sharp contrast with the situation for homogeneous stationary states of a Vlasov equation, where a control over strictly more than one derivative is needed to ensure the absence of unstable stationary states in a neighborhood of a reference stationary state [Z. Lin and C. Zeng, Commun. Math. Phys. 306, 291-331 (2011)].
Stationary solutions of SPDEs and infinite horizon BDSDEs with non-Lipschitz coefficients
NASA Astrophysics Data System (ADS)
Zhang, Qi; Zhao, Huaizhong
We prove a general theorem that the Lρ2(R;R)⊗Lρ2(R;R)-valued solution of an infinite horizon backward doubly stochastic differential equation, if exists, gives the stationary solution of the corresponding stochastic partial differential equation. We prove the existence and uniqueness of the Lρ2(R;R)⊗Lρ2(R;R)-valued solutions for backward doubly stochastic differential equations on finite and infinite horizon with linear growth without assuming Lipschitz conditions, but under the monotonicity condition. Therefore the solution of finite horizon problem gives the solution of the initial value problem of the corresponding stochastic partial differential equations, and the solution of the infinite horizon problem gives the stationary solution of the SPDEs according to our general result.
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.
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.
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)
Grach, V. S.; Garasev, M. A.
2015-07-01
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.
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
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.
Modified Navier-Stokes model for nonequilibrium stationary states
NASA Astrophysics Data System (ADS)
Garcia-Colin, L. S.; Velasco, R. M.
1982-10-01
A hydrodynamic model is developed in order to study the features of the behavior of a fluid which is brought to a stationary state by the action of an external gradient in the cases of the action of a thermal gradient and of a constant shear rate. An examination of the sound absorption of the fluid shows that the Stokes-Kirchhoff formula is modified by the presence of the gradients, which suggests an experimental verification of the model which is independent of the magnitude of the real wave vector. In addition, the light scattering of the fluid is examined by computing the Brillouin-Rayleigh spectra which yields in both cases the same shift in the Brillouin peaks previously predicted. However, a small change in the intensity of the peaks due to the modification of the sound-absorption coefficient is predicted by this model. Calculations show a shift of the Rayleigh peak arising from the entropy flow in the case of the thermal gradient and an entropy-production term in the case of the constant rate of shear, while in both cases the order of magnitude of this correction in terms of the wave vector is the same as the terms responsible for the shift in the Brillouin peaks.
Periodic solutions and stationary distribution of mutualism models in random environments
NASA Astrophysics Data System (ADS)
Zhang, Xinhong; Jiang, Daqing; Alsaedi, Ahmed; Hayat, Tasawar
2016-10-01
This paper is concerned with mutualism models in random environments. For the periodic mutualism model disturbed by white noise, using Has'minskii theory of periodic solution, we show that this model admits a nontrivial positive periodic solution. Then sufficient conditions for the existence and global attractivity of the boundary periodic solutions are established. For the mutualism model disturbed by both white noise and telephone noise, sufficient conditions for positive recurrence and the existence of ergodic stationary distribution of the solution are established. Finally, examples are introduced to illustrate the results developed.
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
Multi-hump solutions with small oscillations at infinity for stationary Swift-Hohenberg equation
NASA Astrophysics Data System (ADS)
Deng, Shengfu; Sun, Shu-Ming
2017-02-01
The paper considers the stationary Swift-Hohenberg equation cw-(∂x2+k02)2w-w3=0, where c > 0 is a constant, k02=\\sqrt{c}-μ , and μ >0 is a small parameter. In this case, the linear operator has a pair of real eigenvalues and a pair of purely imaginary eigenvalues. It can be proved that the equation has homoclinic (or single hump) solutions approaching to periodic solutions as |x|\\to +∞ (called single-hump generalized homoclinic solutions). This paper provides the first rigorous proof of existence of homoclinic solutions with two humps which tend to periodic solutions at infinity (or two-hump generalized homoclinic solutions) by pasting two appropriate single-hump generalized homoclinic solutions together. The dynamical system approach is used to reformulate the problem into a classical dynamical system problem and then the solution is decomposed into a decaying part and an oscillatory part at positive infinity. By adjusting some free constants and modifying the single-hump generalized homoclinic solution near negative infinity, it is shown that the solution is reversible with respect to a point near negative infinity. Therefore, the translational invariant and reversibility properties of the system yield a two-hump generalized homoclinic solution. The method may be applied to prove the existence of 2 k -hump solutions for any positive integer k.
Stability of stationary solutions for inflow problem on the micropolar fluid model
NASA Astrophysics Data System (ADS)
Yin, Haiyan
2017-04-01
In this paper, we study the asymptotic behavior of solutions to the initial boundary value problem for the micropolar fluid model in a half-line R+:=(0,∞). We prove that the corresponding stationary solutions of the small amplitude to the inflow problem for the micropolar fluid model are time asymptotically stable under small H1 perturbations in both the subsonic and degenerate cases. The microrotation velocity brings us some additional troubles compared with Navier-Stokes equations in the absence of the microrotation velocity. The proof of asymptotic stability is based on the basic energy method.
Method for Numerical Solution of the Stationary Schrödinger Equation
NASA Astrophysics Data System (ADS)
Knyazev, S. Yu.; Shcherbakova, E. E.
2017-02-01
The aim of this work is to describe a method of numerical solution of the stationary Schrödinger equation based on the integral equation that is identical to the Schrödinger equation. The method considered here allows one to find the eigenvalues and eigensolutions for quantum-mechanical problems of different dimensionality. The method is tested by solving problems for one-dimensional and two-dimensional quantum oscillators, and results of these tests are presented. Satisfactory agreement of the results obtained using this numerical method with well-known analytical solutions is demonstrated.
NASA Astrophysics Data System (ADS)
Li, Yeping; Yang, Xiongfeng
2017-02-01
In this paper, we consider the 3-D compressible viscous magnetohydrodynamic (MHD) equations with some large potential force in bounded rigid vessel. We firstly construct the non-constant stationary solutions of the compressible viscous MHD equations under suitable constitutive assumptions. Next, a critical energy identity is established to achieve a universal stability criterion of the stationary solution. In this case, the stationary solution is exponential stable for any large external potential force. Finally, we show the well-posedness of the initial boundary value problem for the compressible viscous MHD equations with the large potential force, provided that the prescribed initial data is close to the stationary solution. It implies that the set satisfying the stability criterion is not empty.
NASA Astrophysics Data System (ADS)
Uzunov, Ivan M.; Arabadzhiev, Todor N.; Georgiev, Zhivko D.
2015-08-01
We have studied the impact of the higher-order effects: intrapulse Raman scattering (IRS), third-order of dispersion (TOD) and self-steepening (SS) on pulsating solutions, moving fronts and stationary solutions of the complex cubic-quintic Ginzburg-Landau equation (CCQGLE) found in Tsoy and Akhmediev (2005) as well as on the solutions presented in Uzunov et al. (2014). The applied basic equation generalizes the CCQGLE with the IRS, TOD and SS effects. A finite-dimensional dynamical system has been derived using the method of moments. Applying the derived dynamical system alongside with the numerical solution of the generalized CCQGLE performed by means of the fourth-order Runge-Kutta interaction picture method we have found that the influence of IRS and SS is stronger than the impact of TOD for the solutions of Tsoy and Akhmediev (2005). Perturbed pulsating solutions, moving fronts and stationary solutions in the presence of IRS, SS and TOD have been numerically observed. They exist up to some critical values of the parameters of perturbations. For the values of parameters larger than the critical ones the pulsating solutions are transformed into stable stationary solutions or unstable solutions. New localized fluctuating and stationary solutions have been obtained for fairly large values of parameters of IRS and TOD, respectively. The transformation of the stable stationary solution of Uzunov et al. (2014) under the influence of SS into pulsating solution has been numerically observed.
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.
NASA Astrophysics Data System (ADS)
Siettos, C. I.; Gear, C. W.; Kevrekidis, I. G.
2012-08-01
We show how the equation-free approach can be exploited to enable agent-based simulators to perform system-level computations such as bifurcation, stability analysis and controller design. We illustrate these tasks through an event-driven agent-based model describing the dynamic behaviour of many interacting investors in the presence of mimesis. Using short bursts of appropriately initialized runs of the detailed, agent-based simulator, we construct the coarse-grained bifurcation diagram of the (expected) density of agents and investigate the stability of its multiple solution branches. When the mimetic coupling between agents becomes strong enough, the stable stationary state loses its stability at a coarse turning point bifurcation. We also demonstrate how the framework can be used to design a wash-out dynamic controller that stabilizes open-loop unstable stationary states even under model uncertainty.
Time-periodic and stationary solutions to the compressible Hall-magnetohydrodynamic system
NASA Astrophysics Data System (ADS)
Cheng, Ming
2017-04-01
We are concerned with the 3-D compressible Hall-magnetohydrodynamic system with a time-periodic external force in a periodic domain, and establish the existence of a strong time-periodic solution under some smallness and symmetry assumptions by adapting a new approach. The basic idea of the proof is the following. First, we prove the existence of a time-periodic solution to the linearized system by applying the Tychonoff fixed point theorem combined with the energy method and the decay estimates. From the details of the proof, we see that the initial data of the time-periodic solution to the linearized system lies in some convex hull. Then, we construct a set-value function, such that the fixed point of this function is a time-periodic solution of the compressible Hall-magnetohydrodynamic system. The existence of the fixed point is obtained by the Kakutani fixed point theorem. Moreover, we establish the uniqueness of the time-periodic solution and the existence of the stationary solution.
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.
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, Sergio; Miranda, Jose
2016-11-01
We investigate a quasi-two-dimensional system composed by 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. We thank CNPq (Brazilian Research Council) for financial support.
Stationary Source Related Documents for State and Local Transportation
State and Local Transporation Resources is an EPA/OTAQ web page for state and local air quality regulators and transportation planners that offers guidance on how to reduce air pollution from cars, diesel trucks, city and school buses
NASA Astrophysics Data System (ADS)
Génois, Mathieu; Hersen, Pascal; Bertin, Eric; Courrech du Pont, Sylvain; Grégoire, Guillaume
2016-10-01
The exploration of the phase diagram of a minimal model for barchan fields leads to the description of three distinct phases for the system: stationary, percolable, and unstable. In the stationary phase the system always reaches an out-of-equilibrium, fluctuating, stationary state, independent of its initial conditions. This state has a large and continuous range of dynamics, from dilute—where dunes do not interact—to dense, where the system exhibits both spatial structuring and collective behavior leading to the selection of a particular size for the dunes. In the percolable phase, the system presents a percolation threshold when the initial density increases. This percolation is unusual, as it happens on a continuous space for moving, interacting, finite lifetime dunes. For extreme parameters, the system exhibits a subcritical instability, where some of the dunes in the field grow without bound. We discuss the nature of the asymptotic states and their relations to well-known models of statistical physics.
Génois, Mathieu; Hersen, Pascal; Bertin, Eric; Courrech du Pont, Sylvain; Grégoire, Guillaume
2016-10-01
The exploration of the phase diagram of a minimal model for barchan fields leads to the description of three distinct phases for the system: stationary, percolable, and unstable. In the stationary phase the system always reaches an out-of-equilibrium, fluctuating, stationary state, independent of its initial conditions. This state has a large and continuous range of dynamics, from dilute-where dunes do not interact-to dense, where the system exhibits both spatial structuring and collective behavior leading to the selection of a particular size for the dunes. In the percolable phase, the system presents a percolation threshold when the initial density increases. This percolation is unusual, as it happens on a continuous space for moving, interacting, finite lifetime dunes. For extreme parameters, the system exhibits a subcritical instability, where some of the dunes in the field grow without bound. We discuss the nature of the asymptotic states and their relations to well-known models of statistical physics.
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.
Hermite-Gaussian stationary solutions in strongly nonlocal nonlinear optical media
NASA Astrophysics Data System (ADS)
Zhong, Lanhua; Yang, Jing; Ren, Zhanmei; Guo, Qi
2017-01-01
Approximate analytical stationary solutions (SSs) of a cluster of Hermite-Gaussian (HG) shape is obtained in strongly nonlocal nonlinear media by the variational approach. The evolution of the HG SSs shows that when the order n ⩽ 3, they propagate stably and form solitons; otherwise, when n ⩾ 4, they always propagate unstably and evolve into self-trapped speckle-like beams. However, all these SSs maintain nearly invariant statistic beam-width during their propagation. Furthermore, when the input power deviates from the so-called critical power, the unstable HG beam will adjust its beam-width to form a new self-trapped beam, unlike the soliton which will turn to be a breather. But the average beam-widths are independent of the stability of the propagation of the HG SSs.
Entropy production and thermodynamics of nonequilibrium stationary states: a point of view.
Gallavotti, Giovanni
2004-09-01
Entropy might be a not well defined concept if the system can undergo transformations involving stationary nonequilibria. It might be analogous to the heat content (once called "caloric") in transformations that are not isochoric (i.e., which involve mechanical work): it could be just a quantity that can be transferred or created, like heat in equilibrium. The text first reviews the philosophy behind a recently proposed definition of entropy production in nonequilibrium stationary systems. A detailed technical attempt at defining the entropy of a stationary states via their variational properties follows: the unsatisfactory aspects of the results add arguments in favor of the nonexistence of a function of state to be identified with entropy; at the same time new aspects and properties of the phase space contraction emerge.
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)
Hong, Xinguo; Hao, Quan
2009-01-01
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 °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.
Immune network behavior: Oscillations, chaos and stationary states
De Boer, R.J.; Perelson, A.S.; Kevrekidis, I.G.
1994-04-01
The authors report two types of behavior in models of immune networks. The typical behavior of simple models, which involve B cells only, consists of several coexisting steady states. Finite amplitude perturbations may cause the model to switch between different equilibria. The typical behavior of more realistic models, which involve both B cells and antibody, consists of autonomous oscillations and/or chaos. While steady-state behavior leads to easy interpretations in terms of immune memory, oscillatory behavior seems to be in better agreement with experimental data obtained in unimmunized animals. The stability of the steady states, and the structure and interactions of the stable and unstable manifolds of the saddle-type equilibria turn out to be factors influencing the model`s behavior. Whether or not the model is able to attain any form of sustained oscillatory behavior, i.e., limit cycles or chaos, seems to be determined by (global) bifurcations involving the stable and unstable manifolds of the steady states.
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
Diagnostics of many-particle electronic states: non-stationary currents and residual charge dynamics
NASA Astrophysics Data System (ADS)
Maslova, N. S.; Mantsevich, V. N.; Arseyev, P. I.
2017-01-01
We propose the method for identifying many particle electronic states in the system of coupled quantum dots (impurities) with Coulomb correlations. We demonstrate that different electronic states can be distinguished by the complex analysis of localized charge dynamics and non-stationary characteristics. We show that localized charge time evolution strongly depends on the properties of initial state and analyze different time scales in charge kinetics for initially prepared singlet and triplet states. We reveal the conditions for existence of charge trapping effects governed by the selection rules for electron transitions between the states with different occupation numbers.
NASA Astrophysics Data System (ADS)
Sandin, Patrik; Ögren, Magnus; Gulliksson, Mârten
2016-03-01
We formulate a damped oscillating particle method to solve the stationary nonlinear Schrödinger equation (NLSE). The ground-state solutions are found by a converging damped oscillating evolution equation that can be discretized with symplectic numerical techniques. The method is demonstrated for three different cases: for the single-component NLSE with an attractive self-interaction, for the single-component NLSE with a repulsive self-interaction and a constraint on the angular momentum, and for the two-component NLSE with a constraint on the total angular momentum. We reproduce the so-called yrast curve for the single-component case, described in [A. D. Jackson et al., Europhys. Lett. 95, 30002 (2011), 10.1209/0295-5075/95/30002], and produce for the first time an analogous curve for the two-component NLSE. The numerical results are compared with analytic solutions and competing numerical methods. Our method is well suited to handle a large class of equations and can easily be adapted to further constraints and components.
Sandin, Patrik; Ögren, Magnus; Gulliksson, Mårten
2016-03-01
We formulate a damped oscillating particle method to solve the stationary nonlinear Schrödinger equation (NLSE). The ground-state solutions are found by a converging damped oscillating evolution equation that can be discretized with symplectic numerical techniques. The method is demonstrated for three different cases: for the single-component NLSE with an attractive self-interaction, for the single-component NLSE with a repulsive self-interaction and a constraint on the angular momentum, and for the two-component NLSE with a constraint on the total angular momentum. We reproduce the so-called yrast curve for the single-component case, described in [A. D. Jackson et al., Europhys. Lett. 95, 30002 (2011)], and produce for the first time an analogous curve for the two-component NLSE. The numerical results are compared with analytic solutions and competing numerical methods. Our method is well suited to handle a large class of equations and can easily be adapted to further constraints and components.
Not Available
1993-01-01
Objective is to understand the surface science underlying liquid chromatographic separations, enabling improvements in design of chromatographic stationary phases. Progress was made both in use of laser spectroscopy to probe chromatographic surfaces and in developing new stationary phases based on self-assembled monolayers.
Bertini, L; Gabrielli, D; Jona-Lasinio, G; Landim, C
2013-01-11
Nonequilibrium stationary states of thermodynamic systems dissipate a positive amount of energy per unit of time. If we consider transformations of such states that are realized by letting the driving depend on time, the amount of energy dissipated in an unbounded time window then becomes infinite. Following the general proposal by Oono and Paniconi and using results of the macroscopic fluctuation theory, we give a natural definition of a renormalized work performed along any given transformation. We then show that the renormalized work satisfies a Clausius inequality and prove that equality is achieved for very slow transformations, that is, in the quasistatic limit. We finally connect the renormalized work to the quasipotential of the macroscopic fluctuation theory, which gives the probability of fluctuations in the stationary nonequilibrium ensemble.
Self-ordered stationary states of driven quantum degenerate gases in optical resonators
NASA Astrophysics Data System (ADS)
Sandner, R. M.; Niedenzu, W.; Piazza, F.; Ritsch, H.
2015-09-01
We study the role of quantum statistics in the self-ordering of ultracold bosons and fermions moving inside an optical resonator with transverse coherent pumping. For few particles we numerically compute the nonequilibrium dynamics of the density matrix towards the self-ordered stationary state of the coupled atom-cavity system. We include quantum fluctuations of the particles and the cavity field. These fluctuations in conjunction with cavity cooling determine the stationary distribution of the particles, which exhibits a transition from a homogeneous to a spatially ordered phase with the appearance of a superradiant scattering peak in the cavity output spectrum. While the ordering threshold is generally lower for bosons, we confirm the recently predicted zero pump strength threshold for superradiant scattering for fermions when the cavity photon momentum coincides with twice the Fermi momentum.
NASA Astrophysics Data System (ADS)
Korennoy, Ya. A.; Man'ko, V. I.
2017-04-01
Symplectic and optical joint probability representations of quantum mechanics are considered, in which the functions describing the states are the probability distributions with all random arguments (except the argument of time). The general formalism of quantizers and dequantizers determining the star product quantization scheme in these representations is given. Taking the Gaussian functions as the distributions of the tomographic parameters the correspondence rules for most interesting physical operators are found and the expressions of the dual symbols of operators in the form of singular and regular generalized functions are derived. Evolution equations and stationary states equations for symplectic and optical joint probability distributions are obtained.
NASA Astrophysics Data System (ADS)
Korennoy, Ya. A.; Man'ko, V. I.
2016-12-01
Symplectic and optical joint probability representations of quantum mechanics are considered, in which the functions describing the states are the probability distributions with all random arguments (except the argument of time). The general formalism of quantizers and dequantizers determining the star product quantization scheme in these representations is given. Taking the Gaussian functions as the distributions of the tomographic parameters the correspondence rules for most interesting physical operators are found and the expressions of the dual symbols of operators in the form of singular and regular generalized functions are derived. Evolution equations and stationary states equations for symplectic and optical joint probability distributions are obtained.
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
Fullerene triplet states in solution
NASA Astrophysics Data System (ADS)
Ausman, Kevin Douglas
Triplet state pre-equilibration by reversible energy transfer has been observed by transient-absorption spectroscopy in mixed toluene solutions of C70 and C60 and of C70 and C60(CH 3)2. The equilibrium constants governing the asymptotic partitioning of triplet energy in these mixtures were determined as a function of temperature. The enthalpies of these excited states were found from van't Hoff plots of the equilibrium constant data to be -0.1 +/- 0.2 and -3.4 +/- 0.3 kJ mol-1 for C60 and C60 (CH3)2 respectively relative to a C70 triplet energy exchange partner. The corresponding relative entropies are 5.8 +/- 0.5 and -4.0 +/- 1.0 kJ mol-1 K-1 respectively. Transient spectra from high temperature C70/C60(CH3)2 mixed samples revealed evidence of a third, unidentified transient absorber that exhibited different kinetics from the pre-equilibrated triplet pool. Triplet state transient difference spectra and intrinsic decay kinetics were measured and compared for C60 and several derivatives of C 60. These derivatives were C60H2, C60(CH 3)2, ortho-xylyl-C60, N,N'-dimethyl-1,2-ethylenediamine- C 60, C60C(COOCH2CH3)2, and C60O. The spectral locations of the main triplet-triplet absorption peak for these compounds correlates linearly with the observed intrinsic intersystem crossing rate constant. The triplet state persistence of C60 was measured in toluene solution as a function of both ground state concentration and solution temperature. The unimolecular intersystem crossing deactivation channel shows very little thermal activation, whereas the observed bimolecular self-quenching decay channel is found to be highly activated. At room temperature, the deduced exponential lifetime of the solvent-caged encounter complex between triplet and ground state molecules is three orders of magnitude shorter than that of the isolated monomer triplet state. This suggests that the self-quenching process is not a simple perturbation of an isolated molecule's intersystem crossing, but
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.
Transition state structures in solution
Bertran, J.; Lluch, J. M.; Gonzalez-Lafont, A.; Dillet, V.; Perez, V.
1995-04-05
In the present paper the location of transition state structures for reactions in solution has been studied. Continuum model calculations have been carried out on the Friedel-Crafts alkylation reaction and a proton transfer through a water molecule between two oxygen atoms in formic acid. In this model the separation between the chemical system and the solvent has been introduced. On the other hand, the discrete Monte Carlo methodology has also been used to simulate the solvent effect on dissociative electron transfer processes. In this model, the hypothesis of separability is not assumed. Finally, the validity of both approaches is discussed.
Transition state structures in solution
NASA Astrophysics Data System (ADS)
Bertrán, J.; Lluch, J. M.; Gonzàlez-Lafont, A.; Dillet, V.; Pérez, V.
1995-04-01
In the present paper the location of transition state structures for reactions in solution has been studied. Continuum model calculations have been carried out on the Friedel-Crafts alkylation reaction and a proton transfer through a water molecule between two oxygen atoms in formic acid. In this model the separation between the chemical system and the solvent has been introduced. On the other hand, the discrete Monte Carlo methodology has also been used to simulate the solvent effect on dissociative electron transfer processes. In this model, the hypothesis of separability is not assumed. Finally, the validity of both approaches is discussed.
Stationary distribution and periodic solutions for stochastic Holling-Leslie predator-prey systems
NASA Astrophysics Data System (ADS)
Jiang, Daqing; Zuo, Wenjie; Hayat, Tasawar; Alsaedi, Ahmed
2016-10-01
The stochastic autonomous and periodic predator-prey systems with Holling and Leslie type functional response are investigated. For the autonomous system, we prove that there exists a unique stationary distribution, which is ergodic by constructing a suitable Lyapunov function under relatively small white noise. The result shows that, stationary distribution doesn't rely on the existence and the stability of the positive equilibrium in the undisturbed system. Furthermore, for the corresponding non-autonomous system, we show that there exists a positive periodic Markov process under relatively weaker condition. Finally, numerical simulations illustrate our theoretical results.
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.
On metastability and Markov state models for non-stationary molecular dynamics
NASA Astrophysics Data System (ADS)
Koltai, Péter; Ciccotti, Giovanni; Schütte, Christof
2016-11-01
Unlike for systems in equilibrium, a straightforward definition of a metastable set in the non-stationary, non-equilibrium case may only be given case-by-case—and therefore it is not directly useful any more, in particular in cases where the slowest relaxation time scales are comparable to the time scales at which the external field driving the system varies. We generalize the concept of metastability by relying on the theory of coherent sets. A pair of sets A and B is called coherent with respect to the time interval [t1, t2] if (a) most of the trajectories starting in A at t1 end up in B at t2 and (b) most of the trajectories arriving in B at t2 actually started from A at t1. Based on this definition, we can show how to compute coherent sets and then derive finite-time non-stationary Markov state models. We illustrate this concept and its main differences to equilibrium Markov state modeling on simple, one-dimensional examples.
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
NASA Astrophysics Data System (ADS)
Woo, Hyung Jun
2013-11-01
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.
Barra, Felipe; Gaspard, Pierre; Gilbert, Thomas
2009-08-01
Galton boards are models of deterministic diffusion in a uniform external field, akin to driven periodic Lorentz gases, here considered in the absence of dissipation mechanism. Assuming a cylindrical geometry with axis along the direction of the external field, the two-dimensional board becomes a model for one-dimensional mass transport along the direction of the external field. This is a purely diffusive process which admits fractal nonequilibrium stationary states under flux boundary conditions. Analytical results are obtained for the statistics of multibaker maps modeling such a nonuniform diffusion process. A correspondence is established between the local phase-space statistics and their macroscopic counterparts. The fractality of the invariant state is shown to be responsible for the positiveness of the entropy production rate.
Kinetic insights over a PEMFC operating on stationary and oscillatory states.
Mota, Andressa; Gonzalez, Ernesto R; Eiswirth, Markus
2011-12-01
Kinetic investigations in the oscillatory state have been carried out in order to shed light on the interplay between the complex kinetics exhibited by a proton exchange membrane fuel cell fed with poisoned H(2) (108 ppm of CO) and the other in serie process. The apparent activation energy (E(a)) in the stationary state was investigated in order to clarify the E(a) observed in the oscillatory state. The apparent activation energy in the stationary state, under potentiostatic control, rendered (a) E(a) ≈ 50-60 kJ mol(-1) over 0.8 V < E < 0.6 V and (b) E(a) ≈ 10 kJ mol(-1) at E = 0.3 V. The former is related to the H(2) adsorption in the vacancies of the surface poisoned by CO and the latter is correlated to the process of proton conductivity in the membrane. The dependence of the period-one oscillations on the temperature yielded a genuine Arrhenius dependence with two E(a) values: (a) E(a) around 70 kJ mol(-1), at high temperatures, and (b) E(a) around 10-15 kJ mol(-1), at lower temperatures. The latter E(a) indicates the presence of protonic mass transport coupled to the essential oscillatory mechanism. These insights point in the right direction to predict spatial couplings between anode and cathode as having the highest strength as well as to speculate the most likely candidates to promote spatial inhomogeneities.
Finite current stationary states of random walks on one-dimensional lattices with aperiodic disorder
NASA Astrophysics Data System (ADS)
Miki, Hiroshi
2016-11-01
Stationary states of random walks with finite induced drift velocity on one-dimensional lattices with aperiodic disorder are investigated by scaling analysis. Three aperiodic sequences, the Thue-Morse (TM), the paperfolding (PF), and the Rudin-Shapiro (RS) sequences, are used to construct the aperiodic disorder. These are binary sequences, composed of two symbols A and B, and the ratio of the number of As to that of Bs converges to unity in the infinite sequence length limit, but their effects on diffusional behavior are different. For the TM model, the stationary distribution is extended, as in the case without current, and the drift velocity is independent of the system size. For the PF model and the RS model, as the system size increases, the hierarchical and fractal structure and the localized structure, respectively, are broken by a finite current and changed to an extended distribution if the system size becomes larger than a certain threshold value. Correspondingly, the drift velocity is saturated in a large system while in a small system it decreases as the system size increases.
Schnell, Santiago
2014-01-01
The Michaelis-Menten equation is generally used to estimate the kinetic parameters, V and K(M), when the steady-state assumption is valid. Following a brief overview of the derivation of the Michaelis-Menten equation for the single-enzyme, single-substrate reaction, a critical review of the criteria for validity of the steady-state assumption is presented. The application of the steady-state assumption makes the implicit assumption that there is an initial transient during which the substrate concentration remains approximately constant, equal to the initial substrate concentration, while the enzyme-substrate complex concentration builds up. This implicit assumption is known as the reactant stationary assumption. This review presents evidence showing that the reactant stationary assumption is distinct from and independent of the steady-state assumption. Contrary to the widely believed notion that the Michaelis-Menten equation can always be applied under the steady-state assumption, the reactant stationary assumption is truly the necessary condition for validity of the Michaelis-Menten equation to estimate kinetic parameters. Therefore, the application of the Michaelis-Menten equation only leads to accurate estimation of kinetic parameters when it is used under experimental conditions meeting the reactant stationary assumption. The criterion for validity of the reactant stationary assumption does not require the restrictive condition of choosing a substrate concentration that is much higher than the enzyme concentration in initial rate experiments.
Equilibrium and stationary nonequilibrium states in a chain of colliding harmonic oscillators
Sano
2000-02-01
Equilibrium and nonequilibrium properties of a chain of colliding harmonic oscillators (ding-dong model) are investigated. Our chain is modeled as harmonically bounded particles that can only interact with neighboring particles by hard-core interaction. Between the collisions, particles are just independent harmonic oscillators. We are especially interested in the stationary nonequilibrium state of the ding-dong model coupled with two stochastic heat reservoirs (not thermostated) at the ends, whose temperature is different. We check the Gallavotti-Cohen fluctuation theorem [G. Gallavoti and E. G. D. Cohen, Phys. Rev. Lett. 74, 2694 (1995)] and also the Evans-Searles identity [D. Evans and D. Searles, Phys. Rev. E. 50, 1994 (1994)] numerically. It is verified that the former theorem is satisfied for this system, although the system is not a thermostated system.
Cuevas, Carlos; Martinez, Raquel; Berjon, Daniel; Garcia, Narciso
2017-03-01
There is a huge proliferation of surveillance systems that require strategies for detecting different kinds of stationary foreground objects (e.g., unattended packages or illegally parked vehicles). As these strategies must be able to detect foreground objects remaining static in crowd scenarios, regardless of how long they have not been moving, several algorithms for detecting different kinds of such foreground objects have been developed over the last decades. This paper presents an efficient and high-quality strategy to detect stationary foreground objects, which is able to detect not only completely static objects but also partially static ones. Three parallel nonparametric detectors with different absorption rates are used to detect currently moving foreground objects, short-term stationary foreground objects, and long-term stationary foreground objects. The results of the detectors are fed into a novel finite state machine that classifies the pixels among background, moving foreground objects, stationary foreground objects, occluded stationary foreground objects, and uncovered background. Results show that the proposed detection strategy is not only able to achieve high quality in several challenging situations but it also improves upon previous strategies.
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.
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.
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
Stationary charged scalar clouds around black holes in string theory
NASA Astrophysics Data System (ADS)
Bernard, Canisius
2016-10-01
It was reported that Kerr-Newman black holes can support linear charged scalar fields in their exterior regions. These stationary massive charged scalar fields can form bound states, which are called stationary scalar clouds. In this paper, we show that Kerr-Sen black holes can also support stationary massive charged scalar clouds by matching the near- and far-region solutions of the radial part of the Klein-Gordon wave equation. We also review stationary scalar clouds within the background of static electrically charged black hole solutions in the low-energy limit of heterotic string field theory, namely, the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black holes.
Yu, Huapeng; Zhu, Hai; Gao, Dayuan; Yu, Meng; Wu, Wenqi
2015-02-13
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.
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
1981-06-26
T IC APPLIED RESEARCH LABORATORY Post Office Box 30 ^C State College, PA 16801 SEP 1 1981 Approved for Public Release Distribution Unlimited A NAVY ...CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Naval Sea Systems Command 26 June 1981 Department of the Navy 13. NUMBER OF PAGES Washington, DC...128 C.3 a. Schematic of a Circular Cascade Showing the Orientation of the Airfoil Coordinate System in the Global System. b. A Schematic Showing
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.
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.
Stationary convection in dilute solutions of 3He in superfluid 4He
Warkentin, P. A.; Haucke, H. J.; Lucas, P.; Wheatley, J. C.
1980-01-01
Two symmetric, convecting steady states have been observed in a novel cell of unity aspect ratio and studied over a range of temperature for two concentrations of 3He in superfluid 4He. An existing theory due to Parshin has been related to the conditions necessary for convection in this system, defining a Rayleigh number closely analogous to that of a classical one-component Bénard system. Values of this Rayleigh number at the onset of convection calculated from experimental data are found to have little temperature dependence, with an average value near that for a classical one-component fluid in this geometry. The Prandtl number is small and temperature dependent, with a smallest calculated value of 0.05. PMID:16592932
NASA Astrophysics Data System (ADS)
Arndt, Peter F.; Rittenberg, Vladimir
2002-06-01
We further study the stochastic model discussed in ref. 2 in which positive and negative particles diffuse in an asymmetric, CP invariant way on a ring. The positive particles hop clockwise, the negative counter-clockwise and oppositely-charged adjacent particles may swap positions. We extend the analysis of this model to the case when the densities of the charged particles are not the same. The mean-field equations describing the model are coupled nonlinear differential equations that we call the two-component Burgers equations. We find roundabout weak solutions of these equations. These solutions are used to describe the properties of the stationary states of the stochastic model. The values of the currents and of various two-point correlation functions obtained from Monte-Carlo simulations are compared with the mean-field results. Like in the case of equal densities, one finds a pure phase, a mixed phase and a disordered phase.
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.
Reversible State Transition in Nanoconfined Aqueous Solutions
NASA Astrophysics Data System (ADS)
Zhao, Liang; Wang, Chunlei; Liu, Jian; Wen, Binghai; Tu, Yusong; Wang, Zuowei; Fang, Haiping
2014-02-01
Using molecular dynamics simulations, we find a reversible transition between the dispersion and aggregation states of solute molecules in aqueous solutions confined in nanoscale geometry, which is not observed in macroscopic systems. The nanoscale confinement also leads to a significant increase of the critical aggregation concentration (CAC). A theoretical model based on Gibbs free energy calculation is developed to describe the simulation results. It indicates that the reversible state transition is attributed to the low free energy barrier (of order kBT) in between two energy minima corresponding to the dispersion and aggregation states, and the enhancement of the CAC results from the fact that at lower concentrations the number of solute molecules is not large enough to allow the formation of a stable cluster in the confined systems.
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
2015-09-07
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.
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.
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.
Corresponding-states laws for protein solutions.
Katsonis, Panagiotis; Brandon, Simon; Vekilov, Peter G
2006-09-07
The solvent around protein molecules in solutions is structured and this structuring introduces a repulsion in the intermolecular interaction potential at intermediate separations. We use Monte Carlo simulations with isotropic, pair-additive systems interacting with such potentials. We test if the liquid-liquid and liquid-solid phase lines in model protein solutions can be predicted from universal curves and a pair of experimentally determined parameters, as done for atomic and colloid materials using several laws of corresponding states. As predictors, we test three properties at the critical point for liquid-liquid separation: temperature, as in the original van der Waals law, the second virial coefficient, and a modified second virial coefficient, all paired with the critical volume fraction. We find that the van der Waals law is best obeyed and appears more general than its original formulation: A single universal curve describes all tested nonconformal isotropic pair-additive systems. Published experimental data for the liquid-liquid equilibrium for several proteins at various conditions follow a single van der Waals curve. For the solid-liquid equilibrium, we find that no single system property serves as its predictor. We go beyond corresponding-states correlations and put forth semiempirical laws, which allow prediction of the critical temperature and volume fraction solely based on the range of attraction of the intermolecular interaction potential.
Silva, Felipe O.; Hemerly, Elder M.; Leite Filho, Waldemar C.
2017-01-01
This paper presents the second part of a study aiming at the error state selection in Kalman filters applied to the stationary self-alignment and calibration (SSAC) problem of strapdown inertial navigation systems (SINS). The observability properties of the system are systematically investigated, and the number of unobservable modes is established. Through the analytical manipulation of the full SINS error model, the unobservable modes of the system are determined, and the SSAC error states (except the velocity errors) are proven to be individually unobservable. The estimability of the system is determined through the examination of the major diagonal terms of the covariance matrix and their eigenvalues/eigenvectors. Filter order reduction based on observability analysis is shown to be inadequate, and several misconceptions regarding SSAC observability and estimability deficiencies are removed. As the main contributions of this paper, we demonstrate that, except for the position errors, all error states can be minimally estimated in the SSAC problem and, hence, should not be removed from the filter. Corroborating the conclusions of the first part of this study, a 12-state Kalman filter is found to be the optimal error state selection for SSAC purposes. Results from simulated and experimental tests support the outlined conclusions. PMID:28241494
Silva, Felipe O; Hemerly, Elder M; Leite Filho, Waldemar C
2017-02-23
This paper presents the second part of a study aiming at the error state selection in Kalman filters applied to the stationary self-alignment and calibration (SSAC) problem of strapdown inertial navigation systems (SINS). The observability properties of the system are systematically investigated, and the number of unobservable modes is established. Through the analytical manipulation of the full SINS error model, the unobservable modes of the system are determined, and the SSAC error states (except the velocity errors) are proven to be individually unobservable. The estimability of the system is determined through the examination of the major diagonal terms of the covariance matrix and their eigenvalues/eigenvectors. Filter order reduction based on observability analysis is shown to be inadequate, and several misconceptions regarding SSAC observability and estimability deficiencies are removed. As the main contributions of this paper, we demonstrate that, except for the position errors, all error states can be minimally estimated in the SSAC problem and, hence, should not be removed from the filter. Corroborating the conclusions of the first part of this study, a 12-state Kalman filter is found to be the optimal error state selection for SSAC purposes. Results from simulated and experimental tests support the outlined conclusions.
Khokhlova, Svetlana S; Burshtein, Anatoly I
2011-01-21
The Stern-Volmer constants for either pulse-induced or stationary fluorescence being quenched by a contact charge transfer are calculated and their free energy dependencies (the free energy gap laws) are specified. The reversibility of charge transfer is taken into account as well as spin conversion in radical ion pairs, followed by their recombination in either singlet or triplet neutral products. The natural decay of triplets as well as their impurity quenching by ionization are accounted for when estimating the fluorescence quantum yield and its free energy dependence.
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.
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.
Solute retention and the states of water in polyethylene glycol and poly(vinyl alcohol) gels.
Baba, Takayuki; Sakamoto, Ryosaku; Shibukawa, Masami; Oguma, Koichi
2004-06-18
The states of water sorbed in a cross-linked polyethylene glycol (PEG) gel, TSKgel Ether-250, and cross-linked poly(vinyl alcohol) (PVA) gels of different pore sizes, TSKgel Toyopearl HW-40S, 50S, 55S and 75S, were investigated by means of differential scanning calorimetry (DSC). It was found that there were three types of water in these hydrogels, non-freezing water, freezable bound water and free water. The amount of water that functions as the stationary phase in the column packed with the each gel was also estimated by a liquid chromatographic method. The estimated amount of the stationary phase water is in good agreement with the sum of the amount of non-freezing water and that of freezable bound water for HW-40S, 50S and 55S, while it agrees with the amount of only non-freezing water for HW-75S and Ether-250. This means that the stationary phase water consists of non-freezing water and freezable bound water for HW-40S, 50S and 55S, while only non-freezing water functions as the stationary phase in HW-75S and Ether-250 gels. This result can be attributed to the difference in the structure of the gels; the PVA gels containing PVA at relatively high concentrations, HW-40S, 50S and 55S, have a homogeneous gel phase, whereas HW-75S and Ether-250 have a heterogeneous gel phase consisting hydrated polymer domains and macropores with relatively hydrophobic surface. The freezable bound water in Toyopearl HW-40S, 50S and 55S can be regarded as a component of a homogeneous PVA solution phase, while that in HW-75S and Ether-250 may be water isolated in small pores of the hydrophobic domains. The results obtained by the investigation on the retention selectivity of these hydrogels in aqueous solutions supported our postulated view on the structures of the hydrogels.
NASA Astrophysics Data System (ADS)
Pantellini, Filippo; Griton, Léa
2016-10-01
The spatial structure of a steady state plasma flow is shaped by the standing modes with local phase velocity exactly opposite to the flow velocity. The general procedure of finding the wave vectors of all possible standing MHD modes in any given point of a stationary flow requires numerically solving an algebraic equation. We present the graphical procedure (already mentioned by some authors in the 1960's) along with the exact solution for the Alfvén mode and approximate analytic solutions for both fast and slow modes. The technique can be used to identify MHD modes in space and laboratory plasmas as well as in numerical simulations.
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.
NASA Astrophysics Data System (ADS)
Palma, A.; Semprini, E.; Stefani, F.; Talamo, A.
1996-09-01
We found many stationary points (minima and transition states) for the title reaction on the 2A' surface at unrestricted Hartree-Fock self-consistent field (UHF-SCF) level with two different basis sets. Stable adducts, as suggested by previous experimental works, have been ascertained and several reaction paths are obtained through intrinsic reaction coordinate (IRC) calculations. A link to the HNC+OH reaction is possible. Multiconfiguration SCF (MC-SCF) calculations have been carried out for the addition reaction with the lowest energy barrier in order to eliminate the spin contamination error on these geometries. Correlation energy at the stationary points was estimated via a perturbative scheme, Møller-Plesset at fourth order (MP4) which does not seem adequate for such a system, and via multireference double configuration interaction (MR-DCI) with extrapolation to full CI values for ground and first excited states. Electronic excitations may open some reaction channels.
Jiménez, Rolando Placeres; Pupo, Ana Elisa Bergues; Cabrales, Jesús Manuel Bergues; Joa, Javier Antonio González; Cabrales, Luis Enrique Bergues; Nava, Juan José Godina; Aguilera, Andrés Ramírez; Mateus, Miguel Angel O'Farril; Jarque, Manuel Verdecia; Brooks, Soraida Candida Acosta
2011-02-01
Electrotherapy with direct current delivered through implanted electrodes is used for local control of solid tumors in both preclinical and clinical studies. The aim of this research is to develop a solution method for obtaining a three-dimensional analytical expression for potential and electric current density as functions of direct electric current intensity, differences in conductivities between the tumor and the surrounding healthy tissue, and length, number and polarity of electrodes. The influence of these parameters on electric current density in both media is analyzed. The results show that the electric current density in the tumor is higher than that in the surrounding healthy tissue for any value of these parameters. The conclusion is that the solution method presented in this study is of practical interest because it provides, in a few minutes, a convenient way to visualize in 3D the electric current densities generated by a radial electrode array by means of the adequate selection of direct current intensity, length, number, and polarity of electrodes, and the difference in conductivity between the solid tumor and its surrounding healthy tissue.
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.
Plurality of inherent states in equiatomic solid solutions
NASA Astrophysics Data System (ADS)
Demkowicz, M. J.
2017-03-01
We show that single-crystal, equiatomic solid solutions of Lennard-Jones particles have a plurality of inherent states: mechanically stable configurations with identical lattice site occupancies, yet distinct potential-energy minima. External loading triggers transitions between inherent states via localized shear transformations. A plurality of inherent states and mechanically activated transitions between them make equiatomic solid solutions an unusual form of matter: one that is crystalline like single-component metals, yet exhibits localized shear transformations like metallic glasses.
Saum, Stephan H; Müller, Volker
2008-03-01
The moderately halophilic, chloride-dependent bacterium Halobacillus halophilus switches its osmolyte strategy with the salinity in its environment by the production of different compatible solutes. Ectoine is produced predominantly at very high salinities, along with proline. Interestingly, ectoine production is growth phase dependent which led to a more than 1000-fold change in the ectoine : proline ratio from 0.04 in exponential to 27.4 in late stationary phase cultures. The genes encoding the ectoine biosynthesis pathway were identified on the chromosome in the order ectABC. They form an operon that is expressed in a salinity-dependent manner with low-level expression below 1.5 M NaCl but 10-fold and 23-fold increased expression at 2.5 and 3.0 M NaCl respectively. The temporal expression of genes involved in osmoresponse is different with gdh/gln and pro genes being first, followed by ect genes. Chloride had no effect on expression of ect genes, but stimulated cellular EctC synthesis as well as ectoine production. These data demonstrate, for the first time, a growth-phase dependent switch in osmolyte strategy in a moderate halophile and, additionally, represent another piece of the chloride regulon of H. halophilus.
Díaz, J I; Hidalgo, A; Tello, L
2014-10-08
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.
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
Lin, Cheng-Lan; Singco, Brenda; Wu, Ching-Yi; Liang, Pei-Zhu; Cheng, Yi-Jie; Huang, Hsi-Ya
2013-01-11
This study describes the ability of triallyl isocyanurate (TAIC)-co-methacrylate ester polymer monoliths as stationary phases for the separation of hydrophilic compounds (phenolic acids, amino acids and catecholamines) in capillary electrochromatography (CEC) and ultra high pressure liquid chromatography (UHPLC). Several TAIC-co-methacrylate ester polymer monoliths prepared by single-step in situ copolymerization of TAIC, ethylene dimethacrylate (EDMA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS), with or without alkyl methacrylates were characterized by examining the SEM image, surface area, contact angle, and the thermal decomposition temperature. Compared to the conventional methacrylate ester-based monoliths, these proposed monoliths possessed hydrophilic character thus increased wettability which improved chromatographic separation selectivity of polar phenolic acids. Among the proposed TAIC-co-methacrylate monoliths, poly(TAIC-co-EDMA-AMPS-co-stearyl methacrylate (SMA)) showed separation selectivity with an increased analyte resolution from 0.0 to 0.92 for 4-hydroxybenzoic acid and vanillic acid, which were consistently difficult to resolve in the reversed-phase chromatographic mechanism of these monoliths in aqueous mobile phases. Moreover, stable ionization efficiencies were observed when this monolith was combined with ESI-MS detector possibly because an organic solvent-rich sheath liquid was used in the CEC-MS. This study demonstrates the potentiality of novel TAIC-co-methacrylate polymer monoliths in hydrophilic solute separation either in CEC or UHPLC mode.
NASA Astrophysics Data System (ADS)
Tagawa, S.; Washio, M.; Tabata, Y.; Kobayashi, H.
Transient absorption spectra of the solute anion, cation and triplet state and the solute fluorescence in the pulse radiolysis of 0.1 mole 1 -1 biphenyl in cyclohexane were observed on a nanosecond timescale longer than 1 ns after a 20 ps pulse. The formation of the solute excited singlet state is mainly due to the geminate ion recombination reaction even in the high concentrated solutions. The decay of the solute ions obeys the reciprocal square root dependence on time longer than 10 ns from the end of a 10 ps pulse. The slope of this reciprocal square root plots agrees with the literature value on a longer timescale obtained by microwave absorption. The yield of free ions obtained from the intercept of the slope agrees also with the literature values obtained by the field clearing method. Ratio of the formation rate of the solute excited triplet state to the decay rate of the solute anion changes in a time range between 5 and 20 ns. It is very well correlated with a theoretical calculation of spin correlation decay of the germinate ion pairs by Brocklehurst, although the formation of the solute triplet state was observed even on a timescale shorter than 5 ns from the end of a 20 ps pulse, where loss of spin correlation is negligibly small.
NASA Astrophysics Data System (ADS)
Kravtsov, Nikolai V.; Chekina, S. N.
2007-02-01
The effect of a constant magnetic field on the nonlinear radiation dynamics of a monolithic chip ring Nd:YAG laser pumped by modulated radiation is studied experimentally. It is found that the application of a constant magnetic field to the active element of the solid-state ring laser operating in the non-stationary regime results in the displacement of the regions of existence of quasi-periodic and chaotic lasing regimes to the low-frequency region of pump power modulation. In addition, the application of a magnetic field to the active element of the laser gives rise to the spectral nonreciprocity.
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.
NASA Astrophysics Data System (ADS)
Haslauer, Claus; Heißerer, Theresia; Bárdossy, András
2014-05-01
Using Information on Land-use and Capture Zones for non-Stationary State-Wide Interpolation of Groundwater Quality Parameters A novel approach for spatial non-stationary interpolation is presented. This approach takes censored measurements, secondary information in physically based neighbourhoods, and non-Gaussian spatial dependence structures into account. The impact of the improvements of the geostatistical model are evaluated using regional groundwater quality data. Secondary information has an influence on the distribution of the concentration at each interpolation location. In this study, land-use and hydrogeological units are used as two types of secondary information. The influence of the land-use composition of local neighbourhoods at an interpolation location is modelled by mixed distributions of concentrations. The mixture is derived from the distributions of concentrations within groups of similar land-uses. These pure distributions are jointly optimized for all groups of secondary information.Different geometries and sizes of the neighbourhood are used. Additionally, physically-based delineated capture zones are taken into account for evaluating the influence of the neighbourhood on the measurement distribution. Censored measurements, such as measurements below some detection limit, are commonly ignored, but are incorporated in the presented approach both in the marginal distributions and the multivariate distributions via probabilities of non-exceedance. This is an important feature for emerging contaminants, which typically have a large portion of censored measurements. Spatial copulas are multidimensional dependence models that are capable of incorporating not censored and censored measurements. The dependence can deviate from Gaussian dependence and is independent of the marginal distribution. The proposed model is used for estimation based on the measured parameters and for spatial interpolation purposes. The improved quality of the interpolation
Exact Solutions of Relativistic Bound State Problem for Spinless Bosons
NASA Astrophysics Data System (ADS)
Aslanzadeh, M.; Rajabi, A. A.
2017-01-01
We investigated in detail the relativistic bound states of spin-zero bosons under the influence of Coulomb-plus-linear potentials with an arbitrary combination of scalar and vector couplings. Through an exact analytical solution of three-dimensional Klein-Gordon equation, closed form expressions were derived for energy eigenvalues and wave functions and some correlations between potential parameters were found. We also presented the relativistic description of bound states and nonrelativistic limit of the problem in some special cases.
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.
HDG schemes for stationary convection-diffusion problems
NASA Astrophysics Data System (ADS)
Dautov, R. Z.; Fedotov, E. M.
2016-11-01
For stationary linear convection-diffusion problems, we construct and study a hybridized scheme of the discontinuous Galerkin method on the basis of an extended mixed statement of the problem. Discrete schemes can be used for the solution of equations degenerating in the leading part and are stated via approximations to the solution of the problem, its gradient, the flow, and the restriction of the solution to the boundaries of elements. For the spaces of finite elements, we represent minimal conditions responsible for the solvability, stability and accuracy of the schemes.
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.
Khandokhin, P A; Mamaev, Yu A
2015-02-28
The Jones matrix method is used to study the optimal conditions for steady-state generation through intracavity frequency conversion in a solid-state laser under type-II phase matching based on a weakly anisotropic model of an active medium (amplitude and phase anisotropy) and a nonlinear element. The optimal rotation angles of the nonlinear element are found. (nonlinear optical phenomena)
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.
Tau Aggregation Propensity Engrained in Its Solution State
2016-01-01
A peptide fragment of the human tau protein which stacks to form neat cross β-sheet fibrils, resembling that found in pathological aggregation, 273GKVQIINKKLDL284 (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
Excited State Absorption Measurements In Some Scintillator Dye Solutions
NASA Astrophysics Data System (ADS)
Dharamsi, A., N.; Jong, Shawpin; Hassam, A. B.
1986-11-01
Time-resolved excited state triplet-triplet absorption spectra were measured for solutions of 2,5 diphenyloxazole (PPO) and 2,1 napthyl, 5 phenyloxazole (aNPO) in several solvents. Concentration quenching effects due to excimer formation in nonaromatic solvents were observed. A numerical analysis of the experimental results yielded the rate constants for intersystem crossing, triplet quenching by 02, triplet self quenching and the formation of excimers.
Anharmonic densities of states: A general dynamics-based solution
Jellinek, Julius; Aleinikava, Darya
2016-06-07
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.
NASA Astrophysics Data System (ADS)
Kang, Xiaoyan; He, Anqi; Guo, Ran; Chen, Jing; Zhai, Yanjun; Xu, Yizhuang; Noda, Isao; Wu, Jinguang
2016-11-01
The spectral behavior of a pair of 2D asynchronous spectra generated by using the double asynchronous orthogonal sample design (DAOSD) approach on a chemical system is investigated. Two solutes (P and Q) are dissolved in the solution and intermolecular interaction between P and Q is characterized. In this particular system, P occurs in two exchangeable states when it is dissolved in the solutions. Results on mathematical analysis and computer simulation demonstrated that interference unrelated to the intermolecular interaction can be completely removed. Hence the resultant 2D asynchronous spectra generated by using the DAOSD approach can reflect intermolecular interaction reliably. Moreover, properties of cross peaks in different regions of the pair of asynchronous spectra are discussed. In our previous works, cross peaks generated by using the DAOSD and relevant techniques reflect variations on peak position, bandwidth or absorptivity of the characteristic peaks of solutes caused by intermolecular interaction. However, we find that cross peak can still be produced even if intermolecular interaction do not bring about any changes on the characteristic peaks of solutes. Mathematical analysis demonstrates that cross peaks are related to the variations of chemical systems caused by intermolecular interaction at a network level.
Stationary discrete solitons in a driven dissipative Bose-Hubbard chain
NASA Astrophysics Data System (ADS)
Naether, Uta; Quijandría, Fernando; García-Ripoll, Juan José; Zueco, David
2015-03-01
We demonstrate that stationary localized solutions (discrete solitons) exist in one-dimensional Bose-Hubbard lattices with gain and loss in a semiclassical regime. Stationary solutions, by definition, are robust and do not demand state preparation. Losses, unavoidable in experiments, are not a drawback, but a necessary ingredient for these modes to exist. The semiclassical calculations are complemented with their classical limit and dynamics based on a Gutzwiller ansatz. We argue that circuit quantum electrodynamic architectures are ideal platforms for realizing the physics developed here. Finally, within the input-output formalism, we explain how to experimentally access the different phases, including the solitons, of the chain.
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.
Moulds, Rebecca J; Buntine, Mark A; Lawrance, Warren D
2004-09-08
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 < or = 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 < or = 225 cm(-1). This barrier is less than the 240 cm(-1) energy of 30(2), the vibrational level for which the
Wikberg, Erika; Sparrman, Tobias; Viklund, Camilla; Jonsson, Tobias; Irgum, Knut
2011-09-23
2H NMR has been used as a tool for probing the state of water in hydrophilic stationary phases for liquid chromatography at temperatures between -80 and +4 °C. The fraction of water that remained unfrozen in four different neat silicas with nominal pore sizes between 60 and 300 Å, and in silicas with polymeric sulfobetaine zwitterionic functionalities prepared in different ways, could be determined by measurements of the line widths and temperature-corrected integrals of the 2H signals. The phase transitions detected during thawing made it possible to estimate the amount of non-freezable water in each phase. A distinct difference was seen between the neat and modified silicas tested. For the neat silicas, the relationship between the freezing point depression and their pore size followed the expected Gibbs-Thomson relationship. The polymeric stationary phases were found to contain considerably higher amounts of non-freezable water compared to the neat silica, which is attributed to the structural effect that the sulfobetaine polymers have on the water layer close to the stationary phase surface. The sulfobetaine stationary phases were used alongside the 100 Å silica to separate a number of polar compounds in hydrophilic interaction (HILIC) mode, and the retention characteristics could be explained in terms of the surface water structure, as well as by the porous properties of the stationary phases. This provides solid evidence supporting a partitioning mechanism, or at least of the existence of an immobilized layer of water into which partitioning could be occurring.
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
Stationary shapes of deformable particles moving at low Reynolds numbers
NASA Astrophysics Data System (ADS)
Boltz, Horst-Holger; Kierfeld, Jan
2016-11-01
We introduce an iterative solution scheme in order to calculate stationary shapes of deformable elastic capsules which are steadily moving through a viscous fluid at low Reynolds numbers. The iterative solution scheme couples hydrodynamic boundary integral methods and elastic shape equations to find the stationary axisymmetric shape and the velocity of an elastic capsule moving in a viscous fluid governed by the Stokes equation. We use this approach to systematically study dynamical shape transitions of capsules with Hookean stretching and bending energies and spherical resting shape sedimenting under the influence of gravity or centrifugal forces. We find three types of possible axisymmetric stationary shapes for sedimenting capsules with fixed volume: a pseudospherical state, a pear-shaped state, and buckled shapes. Capsule shapes are controlled by two dimensionless parameters, the Föppl-von-Kármán number characterizing the elastic properties and a Bond number characterizing the driving force. For increasing gravitational force the spherical shape transforms into a pear shape. For very large bending rigidity (very small Föppl-von-Kármán number) this transition is discontinuous with shape hysteresis. The corresponding transition line terminates, however, in a critical point, such that the discontinuous transition is not present at typical Föppl-von-Kármán numbers of synthetic capsules. In an additional bifurcation, buckled shapes occur upon increasing the gravitational force.
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.
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.
Extended law of corresponding states for protein solutions
NASA Astrophysics Data System (ADS)
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.
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.
Marenich, Aleksandr V; Cramer, Christopher J; Truhlar, Donald G
2013-08-13
We present a new kind of treatment of the solute-solvent dispersion contribution to the free energy of solvation using a solvation model with state-specific polarizability (SMSSP). To evaluate the solute-solvent dispersion contribution, the SMSSP model utilizes only two descriptors, namely, the spherically averaged dipole polarizability of the solute molecule (either in its ground or excited electronic state) and the refractive index of the solvent. The model was parametrized over 643 ground-state solvation free energy data for 231 solutes in 14 nonpolar, non-hydrogen-bonding solvents. We show that the SMSSP model is applicable to solutes in both the ground and the excited electronic state. For example, in comparison to available experimental data, the model yields qualitatively accurate predictions of the solvatochromic shifts for a number of systems where solute-solvent dispersion is the dominant contributor to the shift.
Van Gorder, Robert A
2013-04-01
We provide a formulation of the local induction approximation (LIA) for the motion of a vortex filament in the Cartesian reference frame (the extrinsic coordinate system) which allows for scaling of the reference coordinate. For general monotone scalings of the reference coordinate, we derive an equation for the planar solution to the derivative nonlinear Schrödinger equation governing the LIA. We proceed to solve this equation perturbatively in small amplitude through an application of multiple-scales analysis, which allows for accurate computation of the period of the planar vortex filament. The perturbation result is shown to agree strongly with numerical simulations, and we also relate this solution back to the solution obtained in the arclength reference frame (the intrinsic coordinate system). Finally, we discuss nonmonotone coordinate scalings and their application for finding self-intersections of vortex filaments. These self-intersecting vortex filaments are likely unstable and collapse into other structures or dissipate completely.
Dynamical and stationary properties of on-line learning from finite training sets.
Luo, Peixun; Wong, K Y Michael
2003-01-01
The dynamical and stationary properties of on-line learning from finite training sets are analyzed by using the cavity method. For large input dimensions, we derive equations for the macroscopic parameters, namely, the student-teacher correlation, the student-student autocorrelation and the learning force fluctuation. This enables us to provide analytical solutions to Adaline learning as a benchmark. Theoretical predictions of training errors in transient and stationary states are obtained by a Monte Carlo sampling procedure. Generalization and training errors are found to agree with simulations. The physical origin of the critical learning rate is presented. Comparison with batch learning is discussed throughout the paper.
Dynamical and stationary properties of on-line learning from finite training sets
NASA Astrophysics Data System (ADS)
Luo, Peixun; Michael Wong, K. Y.
2003-01-01
The dynamical and stationary properties of on-line learning from finite training sets are analyzed by using the cavity method. For large input dimensions, we derive equations for the macroscopic parameters, namely, the student-teacher correlation, the student-student autocorrelation and the learning force fluctuation. This enables us to provide analytical solutions to Adaline learning as a benchmark. Theoretical predictions of training errors in transient and stationary states are obtained by a Monte Carlo sampling procedure. Generalization and training errors are found to agree with simulations. The physical origin of the critical learning rate is presented. Comparison with batch learning is discussed throughout the paper.
Mitavskiy, Boris; Cannings, Chris
2009-01-01
The evolutionary algorithm stochastic process is well-known to be Markovian. These have been under investigation in much of the theoretical evolutionary computing research. When the mutation rate is positive, the Markov chain modeling of an evolutionary algorithm is irreducible and, therefore, has a unique stationary distribution. Rather little is known about the stationary distribution. In fact, the only quantitative facts established so far tell us that the stationary distributions of Markov chains modeling evolutionary algorithms concentrate on uniform populations (i.e., those populations consisting of a repeated copy of the same individual). At the same time, knowing the stationary distribution may provide some information about the expected time it takes for the algorithm to reach a certain solution, assessment of the biases due to recombination and selection, and is of importance in population genetics to assess what is called a "genetic load" (see the introduction for more details). In the recent joint works of the first author, some bounds have been established on the rates at which the stationary distribution concentrates on the uniform populations. The primary tool used in these papers is the "quotient construction" method. It turns out that the quotient construction method can be exploited to derive much more informative bounds on ratios of the stationary distribution values of various subsets of the state space. In fact, some of the bounds obtained in the current work are expressed in terms of the parameters involved in all the three main stages of an evolutionary algorithm: namely, selection, recombination, and mutation.
NASA Astrophysics Data System (ADS)
Kuznetsov, V. I.; Pramanik, Sourav; Gerasimenko, A. B.; Chakrabarti, Nikhil
2017-02-01
The stability properties of a non-neutral plasma diode [Pramanik et al., Phys. Plasmas 23, 103105 (2016)] have been investigated for the stationary states taking arbitrary value of the neutralization parameter. A constant magnetic field is also assumed to be applied externally along the transverse direction. The (η, ɛ)-diagram technique is used to study the stability features of all types of solutions with respect to small aperiodic perturbations. Employing the first order perturbation theory, a relevant dispersion relation has been derived and analyzed for the regimes when electrons are not turned around by the magnetic field. These regimes of solutions belong to the "Normal C branch" and "C-overlap branch" of the "emitter field strength vs. diode gap"-diagrams. With the help of this dispersion relation, both aperiodic and oscillatory stability properties of such solutions have been presented.
NASA Astrophysics Data System (ADS)
Vasil'eva, V. I.; Vorob'eva, E. A.
2012-11-01
The conjugated diffusion transport of amino acid and mineral salt through a profiled sulfo group cation exchange membrane that simulates the extraction of amino acid from wash waters of microbiological production containing mineral components not used in synthesis is studied. The competitive nature of the conjugation of flows resulting in a decrease in the rate of the mass transfer of components and their separation factor is established from a comparative analysis of experimental data on the diffusion transfer of phenylalanine and sodium chloride in the form of hydrogen from individual and mixed solutions through a profiled sulfo group cation exchange membrane. The range of concentrations and the ratio of components in solution corresponding to the effective separation of phenylalanine and sodium chloride are determined.
NASA Astrophysics Data System (ADS)
Yen, C. T.; Tiller, W. A.
1992-03-01
A one-dimensional mathematical analysis is made of the redistribution of solute which occurs during crystal growth from a convected melt. In this analysis, the important contribution from lateral melt convection to one-dimensional solute redistribution analysis is taken into consideration via an annihilation/creation term in the one-dimensional solute transport equation. Calculations of solute redistribution under steady-state conditions have been carried out analytically. It is found that this new solute redistribution model overcomes several weaknesses that occur when applying the Burton, Prim and Slichter solute segregation equation (1953) in real melt growth situations. It is also found that, with this correction, the diffusion coefficients for solute's in liquid silicon are now found to be in the same range as other liquid metal diffusion coefficients.
Burdette, Carolyn Q; Marcus, R Kenneth
2013-02-21
Polypropylene (PP) capillary-channeled polymer (C-CP) fibers are applied for solid phase extraction (SPE) of proteins from aqueous buffer solutions using a micropipette tip-based format. A process was developed in which centrifugation is used as the moving force for solution passage in the loading/washing steps instead of the previously employed manual aspiration. The complete procedure requires ~15 minutes, with the number of samples run in parallel limited only by the capacity of the centrifuge. The method performance was evaluated based on adsorption and elution characteristics of several proteins (cytochrome c, lysozyme, myoglobin, and glucose oxidase) from 150 mM phosphate buffered saline (PBS) solutions. Protein concentration ranges of ~2 to 100 μg mL(-1) were employed and the recovery characteristics determined through UV-Vis absorbance spectrophotometry for protein quantification. The protein loading capacities across the range of proteins was ~1.5 μg for the 5 mg fiber tips. Average recoveries from PBS were determined for each protein sample; cytochrome c ~86%, lysozyme ~80%, myoglobin ~86%, and glucose oxidase ~89%. Recoveries from more complex matrices, synthetic urine and synthetic saliva, were determined to be ~90%. A 10× dilution study for a fixed 1 μg protein application yielded 94 ± 3.2% recoveries. The C-CP tips provided significantly higher recoveries for myoglobin in a 150 mM PBS matrix in comparison to a commercially available protein SPE product, with the added advantages of low cost, rapid processing, and reusability.
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.
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.
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.
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.
Solid state and solution nitrate photochemistry: photochemical evolution of the solid state lattice.
Asher, Sanford A; Tuschel, David D; Vargson, Todd A; Wang, Luling; Geib, Steven J
2011-05-05
We examined the deep UV 229 nm photochemistry of NaNO(3) in solution and in the solid state. In aqueous solution excitation within the deep UV NO(3)¯ strong π → π* transition causes the photochemical reaction NO(3)¯ → NO(2)¯ + O·. We used UV resonance Raman spectroscopy to examine the photon dose dependence of the NO(2)¯ band intensities and measure a photochemical quantum yield of 0.04 at pH 6.5. We also examined the response of solid NaNO(3) samples to 229 nm excitation and also observe formation of NO(2)¯. The quantum yield is much smaller at ∼10(-8). The solid state NaNO(3) photochemistry phenomena appear complex by showing a significant dependence on the UV excitation flux and dose. At low flux/dose conditions NO(2)¯ resonance Raman bands appear, accompanied by perturbed NO(3)¯ bands, indicating stress in the NaNO(3) lattice. Higher flux/dose conditions show less lattice perturbation but SEM shows surface eruptions that alleviate the stress induced by the photochemistry. Higher flux/dose measurements cause cratering and destruction of the NaNO(3) surface as the surface layers are converted to NO(2)¯. Modest laser excitation UV beams excavate surface layers in the solid NaNO(3) samples. At the lowest incident fluxes a pressure buildup competes with effusion to reach a steady state giving rise to perturbed NO(3)¯ bands. Increased fluxes result in pressures that cause the sample to erupt, relieving the pressure.
Osmotic Second Virial Coefficients of Aqueous Solutions from Two-Component Equations of State.
Cerdeiriña, Claudio A; Widom, B
2016-12-29
Osmotic second virial coefficients in dilute aqueous solutions of small nonpolar solutes are calculated from three different two-component equations of state. The solutes are five noble gases, four diatomics, and six hydrocarbons in the range C1-C4. The equations of state are modified versions of the van der Waals, Redlich-Kwong, and Peng-Robinson equations, with an added hydrogen-bonding term for the solvent water. The parameters in the resulting equations of state are assigned so as to reproduce the experimental values and temperature dependence of the density, vapor pressure, and compressibility of the solvent, the gas-phase second virial coefficient of the pure solute, the solubility and partial molecular volume of the solute, and earlier estimates of the solutes' molecular radii. For all 15 solutes, the calculations are done for 298.15 K, whereas for CH4, C2H6, and C3H8 in particular, they are also done as functions of temperature over the full range 278.15-348.15 K. The calculated osmotic virial coefficients are compared with earlier calculations of these coefficients for these solutes and also with the results derived from earlier computer simulations of model aqueous solutions of methane. They are also compared with the experimental gas-phase second virial coefficients of the pure gaseous solutes to determine the effect the mediation of the solvent has on the resulting solute-solute interactions in the solution.
Controlling Molecular Ordering in Solution-State Conjugated Polymers
Zhu, Jiahua; Han, Youngkyu; Kumar, Rajeev; ...
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…
Normalization of bound-state solutions to the Breit equation
Malenfant, J.
1989-03-15
We derive the spin-(1/2), two-particle Breit equation from the Bethe-Salpeter equation with instantaneous interaction kernel, and solve for the relative time dependence of the resulting Bethe-Salpeter amplitude psi(x). As t..-->.. +- infinity, psi(x) increases exponentially in Dirac hole theory, but goes to zero in single-electron theory. Assuming single-electron theory, a normalization condition is derived for psi(r,0), the solution to the Breit equation, from the normalization for the Bethe-Salpeter amplitude.
Generalization of Carey's equality and a theorem on stationary population.
Srinivasa Rao, Arni S R; Carey, James R
2015-09-01
Carey's Equality pertaining to stationary models is well known. In this paper, we have stated and proved a fundamental theorem related to the formation of this Equality. This theorem will provide an in-depth understanding of the role of each captive subject, and their corresponding follow-up duration in a stationary population. We have demonstrated a numerical example of a captive cohort and the survival pattern of medfly populations. These results can be adopted to understand age-structure and aging process in stationary and non-stationary population models.
Stationary Flux in Mesoscopic Noisy Cylinders
NASA Astrophysics Data System (ADS)
Dajka, J.; Łuczka, J.; Szopa, M.
2003-07-01
The aim of this paper is to investigate the existence of the stationary states of current in the mesoscopic cylinder. The dynamics of the flux is governed by a stochastic differential equation. We discuss both the influence of equilibrium (thermal) and non-equilibrium noise sources.
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.
Effect of cross-diffusion on the stationary problem of a prey-predator model with a protection zone
NASA Astrophysics Data System (ADS)
Oeda, Kazuhiro
This paper is concerned with the stationary problem of a prey-predator cross-diffusion system with a protection zone for the prey. We discuss the existence and non-existence of coexistence states of the two species by using the bifurcation theory. As a result, it is shown that the cross-diffusion for the prey has beneficial effects on the survival of the prey when the intrinsic growth rate of the predator is positive. We also study the asymptotic behavior of positive stationary solutions as the cross-diffusion coefficient of the prey tends to infinity.
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.
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.
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.
Mechanism of connective drying of solutions of fish hydrolyzates in a foamed state
NASA Astrophysics Data System (ADS)
Buinov, A. A.; Ginzburg, A. S.; Syroedov, V. I.
1982-07-01
The results of experimental investigations of the kinetics of foam drying of fish hydrolyzates are presented. The dehydration mechanism is analyzed and the enhancement of the process with dehydration of solutions in a foamed state is explained.
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.
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.
Stationary black holes: large D analysis
NASA Astrophysics Data System (ADS)
Suzuki, Ryotaku; Tanabe, Kentaro
2015-09-01
We consider the effective theory of large D stationary black holes. By solving the Einstein equations with a cosmological constant using the 1 /D expansion in near zone of the black hole we obtain the effective equation for the stationary black hole. The effective equation describes the Myers-Perry black hole, bumpy black holes and, possibly, the black ring solution as its solutions. In this effective theory the black hole is represented as an embedded membrane in the background, e.g., Minkowski or Anti-de Sitter spacetime and its mean curvature is given by the surface gravity redshifted by the background gravitational field and the local Lorentz boost. The local Lorentz boost property of the effective equation is observed also in the metric itself. In fact we show that the leading order metric of the Einstein equation in the 1 /D expansion is generically regarded as a Lorentz boosted Schwarzschild black hole. We apply this Lorentz boost property of the stationary black hole solution to solve perturbation equations. As a result we obtain an analytic formula for quasinormal modes of the singly rotating Myers-Perry black hole in the 1 /D expansion.
Wu, Chin H.; Das, Bibhuti B.; Opella, Stanley J.
2010-01-01
13C NMR of isotopically labeled methyl groups has the potential to combine spectroscopic simplicity with ease of labeling for protein NMR studies. However, in most high resolution separated local field experiments, such as polarization inversion spin exchange at the magic angle (PISEMA), that are used to measure 1H–13C hetero-nuclear dipolar couplings, the four-spin system of the methyl group presents complications. In this study, the properties of the 1H–13C hetero-nuclear dipolar interactions of 13C-labeled methyl groups are revealed through solid-state NMR experiments on a range of samples, including single crystals, stationary powders, and magic angle spinning of powders, of 13C3 labeled alanine alone and incorporated into a protein. The spectral simplifications resulting from proton detected local field (PDLF) experiments are shown to enhance resolution and simplify the interpretation of results on single crystals, magnetically aligned samples, and powders. The complementarity of stationary sample and magic angle spinning (MAS) measurements of dipolar couplings is demonstrated by applying polarization inversion spin exchange at the magic angle and magic angle spinning (PISEMAMAS) to unoriented samples. PMID:19896874
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.
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.
Protolytic dissociation of cyanophenols in ground and excited states in alcohol and water solutions
NASA Astrophysics Data System (ADS)
Szczepanik, Beata; Styrcz, Stanisław
2011-08-01
The effect of cyano substituents on acidity in ground and excited states of mono- and dicyanophenols was investigated. The equilibrium dissociation constants of 3,4-dicyanophenol in ground and lowest excited states in water solution and the change of these constants in the excited state during the transfer to the ground state for o-, m-, p-cyanophenol and 3,4-dicyanophenol in alcohol and water solutions were determined. It was shown that the cyano substitution increases the acidity of ortho-, meta- and dicyano-derivative in ground state in comparison to the phenol, which makes the anions of these derivatives appear in solutions from methanol to 1-butanol. In the excited state the acidity of investigated compounds changes significantly in comparison to the ground state. 3,4-Dicyanophenol is the strongest acid in the lowest excited singlet state, while p-cyanophenol is the weakest one in both alcohol and water solutions. The distribution of the electronic charge and dipole moments of all investigated cyanophenols in ground and excited states were determined on the basis of ab initio calculations using the GAMESS program.
Efficient Steady-State Solution Techniques for Variably Saturated Groundwater Flow
NASA Astrophysics Data System (ADS)
Farthing, M. W.; Kees, C. E.; Coffey, T. S.; Kelley, C. T.; Miller, C. T.
2002-12-01
We consider the simulation of steady-state variably saturated groundwater flow using Richards' equation. The difficulties associated with solving Richards' equation numerically are well known. Most discretization approaches for Richards' equation lead to nonlinear systems that are large and difficult to solve. The solution of nonlinear systems for steady-state problems can be particularly challenging, since a good initial guess for the steady-state solution is often hard to obtain, and the resulting linear systems may be poorly scaled. Common approaches like modified Picard iteration or variations of Newton's method have their advantages but perform poorly with standard globalization techniques under certain conditions. Pseudo-transient continuation has been used in computational fluid dynamics for some time to obtain steady-state solutions for problems in which Newton's method with standard line-search strategies fails. It combines aspects of backward Euler time integration and Newton's method to select intermediate estimates of the steady-state solution. In this work, we examine the use of pseudo-transient continuation methods for Richards' equation. We evaluate their performance for steady-state problems in heterogeneous domains by comparing them with Newton's method using standard globalization techniques. We investigate the methods' performance with both direct and preconditioned Krylov iterative linear solvers. We then make recommendations for robust and efficient approaches to obtain steady-state solutions for Richards' equation under a variety of conditions.
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.
Stationary Phonon Squeezing by Optical Polaron Excitation
NASA Astrophysics Data System (ADS)
Papenkort, T.; Axt, V. M.; Kuhn, T.
2017-03-01
We demonstrate that a stationary squeezed phonon state can be prepared by a pulsed optical excitation of a semiconductor quantum well. Unlike previously discussed scenarios for generating squeezed phonons, the corresponding uncertainties become stationary after the excitation and do not oscillate in time. The effect is caused by two-phonon correlations within the excited polaron. We demonstrate by quantum kinetic simulations and by a perturbation analysis that the energetically lowest polaron state comprises two-phonon correlations which, after the pulse, result in an uncertainty of the lattice momentum that is continuously lower than in the ground state of the semiconductor. The simulations show the dynamics of the polaron formation process and the resulting time-dependent lattice uncertainties.
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.
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.
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.
Quasi-stationary distributions for models of heterogeneous catalysis
NASA Astrophysics Data System (ADS)
de Oliveira, Marcelo M.; Dickman, Ronald
2004-11-01
We construct the quasi-stationary (QS) distribution for two models of heterogeneous catalysis having two absorbing states: the ZGB model for the oxidation of CO, and a version with noninstantaneous reactions. Using a mean-field-like approximation, we study the quasi-stationary surface coverages, moment ratios and the lifetime of the QS state. We also derive an improved, consistent one-site mean-field theory for the ZGB model.
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)…
Asymptotic behavior for the viscous Burgers equation with a stationary source
NASA Astrophysics Data System (ADS)
Chung, Jaywan; Kwon, Ohsang
2016-10-01
Long-time asymptotic behavior for the viscous Burgers equation on the real line is considered. When there is a non-negative and compactly supported Radon measure as a stationary source, we prove that solutions of the viscous Burgers equation converge to a positive, bounded, and nondecreasing steady state by finding an almost optimal convergence order. The non-integrability of the steady state only allows local convergence on compact subsets, hence a Véron-type argument must be modified by adopting a proper weight function.
Test profiles for stationary energy storage applications
Butler, P.C.; Cole, J.F.; Taylor, P.A.
1998-09-01
Evaluation of battery and other energy storage technologies for stationary uses is progressing rapidly toward application-specific testing that uses computer-based data acquisition and control equipment, active electronic loads and power supplies, and customized software, to enable sophisticated test regimes that simulate actual use conditions. These simulated-use tests provide more accurate performance and life evaluations than simple constant resistance or current testing regimes. Some of the tests use stepped constant-power charge and discharge regimes to simulate conditions created by electric utility applications such as frequency regulation and spinning reserve. Other test profiles under development simulate conditions for the energy storage component of Remote Area Power Supplies (RAPS) that include renewable and/or fossil-fueled generators. Various RAPS applications have unique sets of service conditions that require specialized test profiles. However, almost all RAPS tests and many tests that represent other stationary applications need to simulate significant time periods during which 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 effectively predict 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 that are designed to simulate them. The paper also discusses efforts to develop international testing standards.
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.
Iterative solutions to the steady-state density matrix for optomechanical systems
NASA Astrophysics Data System (ADS)
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.
Efficient steady-state solution techniques for variably saturated groundwater flow
NASA Astrophysics Data System (ADS)
Farthing, Matthew W.; Kees, Christopher E.; Coffey, Todd S.; Kelley, C. T.; Miller, Cass T.
We consider the simulation of steady-state variably saturated groundwater flow using Richards' equation (RE). The difficulties associated with solving RE numerically are well known. Most discretization approaches for RE lead to nonlinear systems that are large and difficult to solve. The solution of nonlinear systems for steady-state problems can be particularly challenging, since a good initial guess for the steady-state solution is often hard to obtain, and the resulting linear systems may be poorly scaled. Common approaches like Picard iteration or variations of Newton's method have their advantages but perform poorly with standard globalization techniques under certain conditions. Pseudo-transient continuation has been used in computational fluid dynamics for some time to obtain steady-state solutions for problems in which Newton's method with standard line-search strategies fails. Here, we examine the use of pseudo-transient continuation as well as Newton's method combined with standard globalization techniques for steady-state problems in heterogeneous domains. We investigate the methods' performance with direct and preconditioned Krylov iterative linear solvers. We then make recommendations for robust and efficient approaches to obtain steady-state solutions for RE under a range of conditions.
Singular perturbation solutions of steady-state Poisson-Nernst-Planck systems.
Wang, Xiang-Sheng; He, Dongdong; Wylie, Jonathan J; Huang, Huaxiong
2014-02-01
We study the Poisson-Nernst-Planck (PNP) system with an arbitrary number of ion species with arbitrary valences in the absence of fixed charges. Assuming point charges and that the Debye length is small relative to the domain size, we derive an asymptotic formula for the steady-state solution by matching outer and boundary layer solutions. The case of two ionic species has been extensively studied, the uniqueness of the solution has been proved, and an explicit expression for the solution has been obtained. However, the case of three or more ions has received significantly less attention. Previous work has indicated that the solution may be nonunique and that even obtaining numerical solutions is a difficult task since one must solve complicated systems of nonlinear equations. By adopting a methodology that preserves the symmetries of the PNP system, we show that determining the outer solution effectively reduces to solving a single scalar transcendental equation. Due to the simple form of the transcendental equation, it can be solved numerically in a straightforward manner. Our methodology thus provides a standard procedure for solving the PNP system and we illustrate this by solving some practical examples. Despite the fact that for three ions, previous studies have indicated that multiple solutions may exist, we show that all except for one of these solutions are unphysical and thereby prove the existence and uniqueness for the three-ion case.
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
Anti-periodic solutions of Liénard equations with state dependent impulses
NASA Astrophysics Data System (ADS)
Belley, J.-M.; Bondo, É.
2016-10-01
Subject to a priori bounds, Liénard equations with state dependent impulsive forcing are shown to admit a unique absolutely continuous anti-periodic solution with first derivative of bounded variation on finite intervals. The point-wise convergence of a sequence of iterates to the solution is obtained, along with a bound for the rate of convergence. The results are applied to Josephson's and van der Pol's equations.
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.
Isotope Labeling for Solution and Solid-State NMR Spectroscopy of Membrane Proteins
Verardi, Raffaello; Traaseth, Nathaniel J.; Masterson, Larry R.; Vostrikov, Vitaly V.; Veglia, Gianluigi
2013-01-01
In this chapter, we summarize the isotopic labeling strategies used to obtain high-quality solution and solid-state NMR spectra of biological samples, with emphasis on integral membrane proteins (IMPs). While solution NMR is used to study IMPs under fast tumbling conditions, such as in the presence of detergent micelles or isotropic bicelles, solid-state NMR is used to study the structure and orientation of IMPs in lipid vesicles and bilayers. In spite of the tremendous progress in biomolecular NMR spectroscopy, the homogeneity and overall quality of the sample is still a substantial obstacle to overcome. Isotopic labeling is a major avenue to simplify overlapped spectra by either diluting the NMR active nuclei or allowing the resonances to be separated in multiple dimensions. In the following we will discuss isotopic labeling approaches that have been successfully used in the study of IMPs by solution and solid-state NMR spectroscopy. PMID:23076578
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.
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.
State of ions in electrolyte solutions in the ionic-plasma approximation
Baldanov, M.M.; Mokhosoev, M.V.
1986-04-01
This paper examines the state of ions in the framework of the concept of an ionic plasma. Results are presented of the evaluations of the equivalent conductivity of lithium chloride in aqueous solutions at 18 C. The Debye-Falkenhagne effect and the Wien effect are discussed. The proposed interpretation of the state of ions in electrolyte solutions gives a more natural and more systematic explanation for such factors as the Debye-Falkenhagen dispersion of the electrical conductivity, the Wien effect, and the activity coefficients of electrolytes.
Bound state solutions of the Schrödinger equation for modified Kratzer's molecular potential
NASA Astrophysics Data System (ADS)
Berkdemir, Cüneyt; Berkdemir, Ayşe; Han, Jiaguang
2006-01-01
We present the arbitrary angular momentum solutions of the Schrödinger equation for a diatomic molecule with the modified Kratzer potential De[( r - re)/ r] 2. The bound state energy eigenvalues and the corresponding eigenfunctions are obtained by the use of the Nikiforov-Uvarov (NU) method which is related to the solutions in terms of Jacobi polynomials. The bound states are calculated for various values of ℓ with n ⩽ 5 and applied to several diatomic molecules. All of these calculations present an effective and methodological procedure under the NU method to investigate the Kratzer's molecular systems.
Zeron, E S; Santillán, M
2011-01-01
In this work, we introduce a couple of algorithms to compute the stationary probability distribution for the chemical master equation (CME) of arbitrary chemical networks. We further find the conditions guaranteeing the algorithms' convergence and the unity and stability of the stationary distribution. Next, we employ these algorithms to study the mRNA and protein probability distributions in a gene regulatory network subject to negative feedback regulation. In particular, we analyze the influence of the promoter activation/deactivation speed on the shape of such distributions. We find that a reduction of the promoter activation/deactivation speed modifies the shape of those distributions in a way consistent with the phenomenon known as mRNA (or transcription) bursting.
Uniqueness of Positive Ground State Solutions of the Logarithmic Schrödinger Equation
NASA Astrophysics Data System (ADS)
Troy, William C.
2016-12-01
We prove the uniqueness of positive ground state solutions of the problem { {{d2u}/{dr2}} + {{n-1}/{r}}{du/dr}} + u ln(|u|) = 0}, {u(r) > 0 forall r ≥ 0}, and {(u(r),u'(r)) to (0, 0)} as {r to ∞}. This equation is derived from the logarithmic Schrödinger equation {iψt = {Δ} ψ + u ln (|u|2)}, and also from the classical equation {{{partial u}/{partial t}} = {Δ} u +u (|u|^{p-1}) -u}. For each {n ≥ 1}, a positive ground state solution is { u0(r) = exp (-{r^2/4} + {n/2}), 0 ≤ r < ∞}. We combine {u0(r)} with energy estimates and associated Ricatti equation estimates to prove that, for each {n in [1, 9 ]}, {u0(r)} is the only positive ground state. We also investigate the stability of {u0(r)}. Several open problems are stated.
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.
Co-existence of Distinct Supramolecular Assemblies in Solution and in the Solid State.
Reddy, G N Manjunatha; Huqi, Aida; Iuga, Dinu; Sakurai, Satoshi; Marsh, Andrew; Davis, Jeffery T; Masiero, Stefano; Brown, Steven P
2017-02-16
The formation of distinct supramolecular assemblies, including a metastable species, is revealed for a lipophilic guanosine (G) derivative in solution and in the solid state. Structurally different G-quartet-based assemblies are formed in chloroform depending on the nature of the cation, anion and the salt concentration, as characterized by circular dichroism and time course diffusion-ordered NMR spectroscopy data. Intriguingly, even the presence of potassium ions that stabilize G-quartets in chloroform was insufficient to exclusively retain such assemblies in the solid state, leading to the formation of mixed quartet and ribbon-like assemblies as revealed by fast magic-angle spinning (MAS) NMR spectroscopy. Distinct N-H⋅⋅⋅N and N-H⋅⋅⋅O intermolecular hydrogen bonding interactions drive quartet and ribbon-like self-assembly resulting in markedly different 2D (1) H solid-state NMR spectra, thus facilitating a direct identification of mixed assemblies. A dissolution NMR experiment confirmed that the quartet and ribbon interconversion is reversible-further demonstrating the changes that occur in the self-assembly process of a lipophilic nucleoside upon a solid-state to solution-state transition and vice versa. A systematic study for complexation with different cations (K(+) , Sr(2+) ) and anions (picrate, ethanoate and iodide) emphasizes that the existence of a stable solution or solid-state structure may not reflect the stability of the same supramolecular entity in another phase.
A solution state diode using semiconductor polymer nanorods with nanogap electrodes.
Mutlu, Senol; Sonmez, Bedri Gurkan
2012-06-22
A solution state polymer diode, which uses regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT):dichlorobenzene solution as the semiconductor between highly doped p-type silicon and aluminum electrodes has been built. Electrodes separated by a 40 nm gap enable intra-chain charge carrier transfer through the lengths of single polymer chains. This prevents chain to chain hopping and chain entanglements, increasing carrier mobility. The degradation with time and hysteresis effects of the diodes are measured. An optimal P3HT solution concentration of 6 mg ml(-1) is found. A current density of at least 300 mA cm(-2) is achieved, indicating at least a six-fold improvement in carrier mobility compared to previously fabricated solid state P3HT diodes.
Existence of ground state solutions to Dirac equations with vanishing potentials at infinity
NASA Astrophysics Data System (ADS)
Figueiredo, Giovany M.; Pimenta, Marcos T. O.
2017-01-01
In this work we study the existence of ground-state solutions of Dirac equations with potentials which are allowed to vanish at infinity. The approach is based on minimization of the energy functional over a generalized Nehari set. Some conditions on the potentials are given in order to overcome the lack of compactness.
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 ...
The equation of state for solutions of the sunflower oil+isomerhexane system
NASA Astrophysics Data System (ADS)
Safarov, M. M.; Abdukhamidova, Z.
1995-11-01
The article presents the results of an experimental investigation into the density of solutions of the sunflower oil+isomerhexane system (from 23 to 75%) at temperatures of from 293 to 450 K and pressures of from 0.101 to 98.1 MPa. An equation of state is obtained.
Raynal, Philippe; Luetkenhaus, Norbert
2005-08-15
Recently the problem of unambiguous state discrimination of mixed quantum states has attracted much attention. So far, bounds on the optimum success probability have been derived [T. Rudolph, R. W. Spekkens, and P. S. Turner, Phys. Rev. A 68, 010301(R) (2003)]. For two mixed states they are given in terms of the fidelity. Here we give tighter bounds as well as necessary and sufficient conditions for two mixed states to reach these bounds. Moreover we construct the corresponding optimal measurement strategies. With this result, we provide analytical solutions for unambiguous discrimination of a class of generic mixed states. This goes beyond known results which are all reducible to some pure state case. Additionally, we show that examples exist where the bounds cannot be reached.
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.
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.
Stationary Black Holes: Uniqueness and Beyond.
Chruściel, Piotr T; Costa, João Lopes; Heusler, Markus
2012-01-01
The spectrum of known black-hole solutions to the stationary Einstein equations has been steadily increasing, sometimes in unexpected ways. In particular, it has turned out that not all black-hole-equilibrium configurations are characterized by their mass, angular momentum and global charges. Moreover, the high degree of symmetry displayed by vacuum and electro-vacuum black-hole spacetimes ceases to exist in self-gravitating non-linear field theories. This text aims to review some developments in the subject and to discuss them in light of the uniqueness theorem for the Einstein-Maxwell system.
Gillet, Sébastien; Aguedo, Mario; Petrut, Raul; Olive, Gilles; Anastas, Paul; Blecker, Christophe; Richel, Aurore
2017-03-01
Two fractions of carob galactomannans (GM25 and GM80) were extracted at respectively 25°C and 80°C from crude locust bean gum. Those fractions having slightly different chemical structures, previously characterized, were studied for their viscosity properties over a wide range of concentrations: diluted solution, unperturbed state and gel state. For each of the physical properties, links to the chemical fine structure could be established, expanding knowledge on the topic: in dilute solution, GM25 is more soluble in water while GM80 seems to tend to self-association due to its structure as highlighted by intrinsic viscosity measurements ([η]GM25=9.96dLg(-1) and [η]GM80=4.04dLg(-1)). In unperturbed state, initial viscosities η0 were more important for GM80 fractions at 1% and 2% due to greater hyperentanglements (η0(GM80,1%)=9.9Pas; η0(GM80,2%)=832.0; Pa.s η0(GM25,1%)=3.1Pas; η0(GM25,2%)=45.1Pas). In gel state, hydrogels obtained from GM80 were also stronger (hardness GM80 (2%)=0.51N and hardness GM25 (2%)=0.11N), suggesting a much more important number of junction areas within the gel network. The findings discussed herein demonstrate the potential for new applications.
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
Shim, Jaesool; Yoo, Kisoo; Dutta, Prashanta
2017-03-01
The determination of an analytical solution to find the steady-state protein concentration distribution in IEF is very challenging due to the nonlinear coupling between mass and charge conservation equations. In this study, approximate analytical solutions are obtained for steady-state protein distribution in carrier ampholyte based IEF. Similar to the work of Svensson, the final concentration profile for proteins is assumed to be Gaussian, but appropriate expressions are presented in order to obtain the effective electric field and pH gradient in the focused protein band region. Analytical results are found from iterative solutions of a system of coupled algebraic equations using only several iterations for IEF separation of three plasma proteins: albumin, cardiac troponin I, and hemoglobin. The analytical results are compared with numerically predicted results for IEF, showing excellent agreement. Analytically obtained electric field and ionic conductivity distributions show significant deviation from their nominal values, which is essential in finding the protein focusing behavior at isoelectric points. These analytical solutions can be used to determine steady-state protein concentration distribution for experiment design of IEF considering any number of proteins and ampholytes. Moreover, the model presented herein can be used to find the conductivity, electric field, and pH field.
Deremigio, Hilary; Kemper, Peter; Lamar, M Drew; Smith, Gregory D
2008-01-01
Mathematical models of calcium release sites derived from Markov chain models of intracellular calcium channels exhibit collective gating reminiscent of the experimentally observed phenomenon of stochastic calcium excitability (i.e., calcium puffs and sparks). We present a Kronecker structured representation for calcium release site models and perform benchmark stationary distribution calculations using numerical iterative solution techniques that leverage this structure. In this context we find multi-level methods and certain preconditioned projection methods superior to simple Gauss-Seidel type iterations. Response measures such as the number of channels in a particular state converge more quickly using these numerical iterative methods than occupation measures calculated via Monte Carlo simulation.
Theory of a stationary microwave discharge with multiply charged ions in an expanding gas jet
NASA Astrophysics Data System (ADS)
Shalashov, A. G.; Abramov, I. S.; Golubev, S. V.; Gospodchikov, E. D.
2016-08-01
The formation of a jet of a nonequilibrium multiply charged ion plasma is studied in the inhomogeneous gas jet. It is shown that the geometrical divergence of the jet restricts the maximum ion charge state and results in the spatial localization of the discharge. Stationary solutions corresponding to such regimes are constructed. The model proposed can be used to optimize modern experiments on generation of hard UV radiation due to the line emission of multiply ionized atoms in a gas jet heated by high-power millimeter and submillimeter radiation.
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.
A hybrid multigrid technique for computing steady-state solutions to supersonic flows
NASA Technical Reports Server (NTRS)
Sanders, Richard
1992-01-01
Recently, Li and Sanders have introduced a class of finite difference schemes to approximate generally discontinuous solutions to hyperbolic systems of conservation laws. These equations have the form together with relevant boundary conditions. When modelling hypersonic spacecraft reentry, the differential equations above are frequently given by the compressible Euler equations coupled with a nonequilibrium chemistry model. For these applications, steady state solutions are often sought. Many tens (to hundreds) of super computer hours can be devoted to a single three space dimensional simulation. The primary difficulty is the inability to rapidly and reliably capture the steady state. In these notes, we demonstrate that a particular variant from the schemes presented can be combined with a particular multigrid approach to capture steady state solutions to the compressible Euler equations in one space dimension. We show that the rate of convergence to steady state coming from this multigrid implementation is vastly superior to the traditional approach of artificial time relaxation. Moreover, we demonstrate virtual grid independence. That is, the rate of convergence does not depend on the degree of spatial grid refinement.
Influence of Stationary Crossflow Modulation on Secondary Instability
NASA Technical Reports Server (NTRS)
Choudhari, Meelan M.; Li, Fei; Paredes, Pedro
2016-01-01
A likely scenario for swept wing transition on subsonic aircraft with natural laminar flow involves the breakdown of stationary crossflow vortices via high frequency secondary instability. A majority of the prior research on this secondary instability has focused on crossflow vortices with a single dominant spanwise wavelength. This paper investigates the effects of the spanwise modulation of stationary crossflow vortices at a specified wavelength by a subharmonic stationary mode. Secondary instability of the modulated crossflow pattern is studied using planar, partial-differential-equation based eigenvalue analysis. Computations reveal that weak modulation by the first subharmonic of the input stationary mode leads to mode splitting that is particularly obvious for Y-type secondary modes that are driven by the wall-normal shear of the basic state. Thus, for each Y mode corresponding to the fundamental wavelength of results in unmodulated train of crossflow vortices, the modulated flow supports a pair of secondary modes with somewhat different amplification rates. The mode splitting phenomenon suggests that a more complex stationary modulation such as that induced by natural surface roughness would yield a considerably richer spectrum of secondary instability modes. Even modest levels of subharmonic modulation are shown to have a strong effect on the overall amplification of secondary disturbances, particularly the Z-modes driven by the spanwise shear of the basic state. Preliminary computations related to the nonlinear breakdown of these secondary disturbances provide interesting insights into the process of crossflow transition in the presence of the first subharmonic of the dominant stationary vortex.
On the Oxidation State of Manganese Ions in Li-Ion Battery Electrolyte Solutions.
Banerjee, Anjan; Shilina, Yuliya; Ziv, Baruch; Ziegelbauer, Joseph M; Luski, Shalom; Aurbach, Doron; Halalay, Ion C
2017-02-08
We demonstrate herein that Mn(3+) and not Mn(2+), as commonly accepted, is the dominant dissolved manganese cation in LiPF6-based electrolyte solutions of Li-ion batteries with lithium manganate spinel positive and graphite negative electrodes chemistry. The Mn(3+) fractions in solution, derived from a combined analysis of electron paramagnetic resonance and inductively coupled plasma spectroscopy data, are ∼80% for either fully discharged (3.0 V hold) or fully charged (4.2 V hold) cells, and ∼60% for galvanostatically cycled cells. These findings agree with the average oxidation state of dissolved Mn ions determined from X-ray absorption near-edge spectroscopy data, as verified through a speciation diagram analysis. We also show that the fractions of Mn(3+) in the aprotic nonaqueous electrolyte solution are constant over the duration of our experiments and that disproportionation of Mn(3+) occurs at a very slow rate.
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
West, C; Lesellier, E
2006-03-31
In this third paper, varied types of polar stationary phases, namely silica gel (SI), cyano (CN)- and amino-propyl (NH2)-bonded silica, propanediol-bonded silica (DIOL), poly(ethylene glycol) (PEG) and poly(vinyl alcohol) (PVA), were investigated in subcritical fluid mobile phase. This study was performed to provide a greater knowledge of the properties of these phases in SFC, and to allow a more rapid and efficient choice of polar stationary phase in regard of the chemical nature of the solutes to be separated. The effect of the nature of the stationary phase on interactions between solute and stationary phases and between solute and carbon dioxide-modifier mobile phases was studied by the use of a linear solvation energy relationship (LSER), the solvation parameter model. The retention behaviour observed with sub/supercritical fluid with carbon dioxide-methanol is close to the one reported in normal-phase liquid chromatography with hexane. The hydrogen bond acidity and basicity, and the polarity/polarizability favour the solute retention when the molar volume of the solute reduces it. As with non-polar phases, the absence of water in the subcritical fluid allows the solute/stationary phase interactions to play a greater part in the retention behaviour. As expected, the DIOL phase and the bare silica display a similar behaviour towards acidic and basic solutes, when interactions with basic compounds are lower with the NH2 phase. On the CN phase, all interactions (hydrogen bonding, dipole-dipole and charge transfer) have a nearly equivalent weight on the retention. The polymeric phases, PEG and PVA, provide the most accurate models, possibly due to their better surface homogeneity.
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.
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.
NASA Astrophysics Data System (ADS)
Leray, Sarah; Engdahl, Nicholas B.; Massoudieh, Arash; Bresciani, Etienne; McCallum, James
2016-12-01
This review presents the physical mechanisms generating residence time distributions (RTDs) in hydrologic systems with a focus on steady-state analytical solutions. Steady-state approximations of the RTD in hydrologic systems have seen widespread use over the last half-century because they provide a convenient, simplified modeling framework for a wide range of problems. The concept of an RTD is useful anytime that characterization of the timescales of flow and transport in hydrologic systems is important, which includes topics like water quality, water resource management, contaminant transport, and ecosystem preservation. Analytical solutions are often adopted as a model of the RTD and a broad spectrum of models from many disciplines has been applied. Although these solutions are typically reduced in dimensionality and limited in complexity, their ease of use makes them preferred tools, specifically for the interpretation of tracer data. Our review begins with the mechanistic basis for the governing equations, highlighting the physics for generating a RTD, and a catalog of analytical solutions follows. This catalog explains the geometry, boundary conditions and physical aspects of the hydrologic systems, as well as the sampling conditions, that altogether give rise to specific RTDs. The similarities between models are noted, as are the appropriate conditions for their applicability. The presentation of simple solutions is followed by a presentation of more complicated analytical models for RTDs, including serial and parallel combinations, lagged systems, and non-Fickian models. The conditions for the appropriate use of analytical solutions are discussed, and we close with some thoughts on potential applications, alternative approaches, and future directions for modeling hydrologic residence time.
Optical limiting and excited-state absorption in fullerene solutions and doped glasses
McBranch, D.; Smilowitz, L.; Klimov, V.
1995-09-01
We report the ground state and excited state optical absorption spectra in the visible and near infrared for several substituted fullerenes and higher fullerenes in toluene solutions. Based on these measurements, broadband predictions of the optical limiting performance of these molecules can be deduced. These predictions are then tested at 532 to 700 nm in intensity-dependent transmission measurements. We observe optical limiting in all fullerenes measured; higher fullerenes show the greatest potential for limiting in the near infrared (650-1000 nm), while substituted C{sub 60} shows optimal limiting in the visible (450-700 nm). We observe dramatically reduced limiting for solid forms of C{sub 60} (thin films and C{sub 60}-doped porous glasses), indicating that efficient optical limiting in fullerenes requires true molecular solutions.
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.
Active Control of Stationary Vortices
NASA Astrophysics Data System (ADS)
Nino, Giovanni; Breidenthal, Robert; Bhide, Aditi; Sridhar, Aditya
2016-11-01
A system for active stationary vortex control is presented. The system uses a combination of plasma actuators, pressure sensors and electrical circuits deposited on aerodynamic surfaces using printing electronics methods. Once the pressure sensors sense a change on the intensity or on the position of the stationary vortices, its associated controller activates a set of plasma actuator to return the vortices to their original or intended positions. The forces produced by the actuators act on the secondary flow in the transverse plane, where velocities are much less than in the streamwise direction. As a demonstration case, the active vortex control system is mounted on a flat plate under low speed wind tunnel testing. Here, a set of vortex generators are used to generate the stationary vortices and the plasma actuators are used to move them. Preliminary results from the experiments are presented and compared with theoretical values. Thanks to the USAF AFOSR STTR support under contract # FA9550-15-C-0007.
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.
Optimal unambiguous state discrimination of two density matrices: A second class of exact solutions
Raynal, Philippe; Luetkenhaus, Norbert
2007-11-15
We consider the unambiguous state discrimination (USD) of two mixed quantum states. We study the rank and the spectrum of the elements of an optimal USD measurement. This naturally leads to a partial fourth reduction theorem. This theorem shows that either the failure probability equals its overall lower bound given in terms of the fidelity or a two-dimensional subspace can be split off from the original Hilbert space. We then use this partial reduction theorem to derive the optimal solution for any two equally probable geometrically uniform states {rho}{sub 0} and {rho}{sub 1}=U{rho}{sub 0}U{sup {dagger}}, U{sup 2}=1, in a four-dimensional Hilbert space. This represents a second class of analytical solutions for USD problems that cannot be reduced to some pure state cases. We apply our result to answer two questions that are relevant in implementations of the Bennett and Brassard 1984 quantum key distribution protocol using weak coherent states.
Halász, Adám M; Lai, Hong-Jian; McCabe Pryor, Meghan; Radhakrishnan, Krishnan; Edwards, Jeremy S
2013-01-01
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.
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
Probing the excited state relaxation dynamics of pyrimidine nucleosides in chloroform solution.
Röttger, Katharina; Marroux, Hugo J B; Böhnke, Hendrik; Morris, David T J; Voice, Angus T; Temps, Friedrich; Roberts, Gareth M; Orr-Ewing, Andrew J
2016-12-16
Ultrafast transient electronic and vibrational absorption spectroscopy (TEAS and TVAS) of 2'-deoxy-cytidine (dC) and 2'-deoxy-thymidine (dT) dissolved in chloroform examines their excited-state dynamics and the recovery of ground electronic state molecules following absorption of ultraviolet light. The chloroform serves as a weakly interacting solvent, allowing comparisons to be drawn with prior experimental studies of the photodynamics of these nucleosides in the gas phase and in polar solvents such as water. The pyrimidine base nucleosides have some propensity to dimerize in aprotic solvents, but the monomer photochemistry can be resolved clearly and is the focus of this study. UV absorption at a wavelength of 260 nm excites a (1)ππ* ← S0 transition, but prompt crossing of a significant fraction (50% in dC, 17% in dT) of the (1)ππ* population into a nearby (1)nπ* state is too fast for the experiments to resolve. The remaining flux on the (1)ππ* state leaves the vertical Franck-Condon region and encounters a conical intersection with the ground electronic state of ethylenic twist character. In dC, the (1)ππ* state decays to the ground state with a time constant of 1.1 ± 0.1 ps. The lifetime of the (1)nπ* state is much longer in the canonical forms of both molecules: recovery of the ground state population from these states occurs with time constants of 18.6 ± 1.1 ps in amino-oxo dC and ∼114 ps in dT, indicating potential energy barriers to the (1)nπ*/S0 conical intersections. The small fraction of the imino-oxo tautomer of dC present in solution has a longer-lived (1)nπ* state with a lifetime for ground state recovery of 193 ± 55 ps. No evidence is found for photo-induced tautomerization of amino-oxo dC to the imino-oxo form, or for population of low lying triplet states of this nucleoside. In contrast, ∼8% of the UV-excited dT molecules access the long-lived T1 ((3)ππ*) state through the (1)nπ* state. The primary influence of the solvent
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
Li, Jianguo; Hu, Zhongqiao; Beuerman, Roger; Verma, Chandra
2017-04-06
Human β-defensin 2 is a cysteine-rich antimicrobial peptide. In the crystal state, the N-terminal segment (residues 1-11) exhibits a helical conformation. However, a truncated form, with four amino acids removed from the N-terminus, adopts nonhelical conformations in solution, as shown by NMR. To explore the molecular origins of these different conformations, we performed Hamiltonian replica exchange molecular dynamics simulations of the peptide in solution and in the crystal state. It is found that backbone hydration and specific protein-protein interactions are key parameters that determine the peptide conformation. The helical conformation in the crystal state mainly arises from reduced hydration as well as a salt bridge between the peptide and a symmetry-related neighboring monomer in the crystal. When the extent of hydration is reduced and the salt bridge is reintroduced artificially, the peptide is successfully folded back to the helical conformation in solution. The findings not only shed light on the development of accurate force field parameters for protein molecules but also provide practical guidance in the design of functional proteins and peptides.
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
2011-05-01
Successfully Demonstrating an Integrated Roofing and BIPV Solution for an Historic Building Renovation at the United States Air Force Academy...COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Successfully Demonstrating an Integrated Roofing and BIPV Solution for an Historic...ANSI Std Z39-18 Successfully Demonstrating an Integrated Roofing and BIPV Solution for an Historic Building Renovation at the United States Air Force
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…
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.
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.
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.
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.
Sivchik, Vasily V; Grachova, Elena V; Melnikov, Alexei S; Smirnov, Sergey N; Ivanov, Alexander Yu; Hirva, Pipsa; Tunik, Sergey P; Koshevoy, Igor O
2016-04-04
The noncovalent intermolecular interactions (π-π stacking, metallophilic bonding) of the cyclometalated complexes [Pt(NCN)L](+)X(-) (NCN = dipyridylbenzene, L = pyridine (1), acetonitrile (2)) are determined by the steric properties of the ancillary ligands L in the solid state and in solution, while the nature of the counterion X(-) (X(-) = PF6(-), ClO4(-), CF3SO3(-)) affects the molecular arrangement of 2·X in the crystal medium. According to the variable-temperature X-ray diffraction measurements, the extensive Pt···Pt interactions and π-stacking in 2·X are significantly temperature-dependent. The variable concentration (1)H and diffusion coefficients NMR measurements reveal that 2·X exists in the monomeric form in dilute solutions at 298 K, while upon increase in concentration [Pt(NCN)(NCMe)](+) cations undergo the formation of the ground-state oligomeric aggregates with an average aggregation number of ∼3. The photoluminescent characteristics of 1 and 2·X are largely determined by the intermolecular aggregation. For the discrete molecules the emission properties are assigned to metal perturbed IL charge transfer mixed with some MLCT contribution. In the case of oligomers 2·X the luminescence is significantly red-shifted with respect to 1 and originates mainly from the (3)MMLCT excited states. The emission energies depend on the structural arrangement in the crystal and on the complex concentration in solution, variation of which allows for the modulation of the emission color from greenish to deep red. In the solid state the lability of the ligands L leads to vapor-induced reversible transformation 1 ↔ 2 that is accompanied by the molecular reorganization and, consequently, dramatic change of the photophysical properties. Time-dependent density functional theory calculations adequately support the models proposed for the rationalization of the experimental observations.
The finite state projection algorithm for the solution of the chemical master equation
NASA Astrophysics Data System (ADS)
Munsky, Brian; Khammash, Mustafa
2006-01-01
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 τ 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 τ 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 τ leaping methods.
Cosmic ray heating in cool core clusters I: diversity of steady state solutions
NASA Astrophysics Data System (ADS)
Jacob, Svenja; Pfrommer, Christoph
2017-01-01
The absence of large cooling flows in cool core clusters appears to require self-regulated energy feedback by active galactic nuclei (AGNs) but the exact heating mechanism has not yet been identified. Here, we analyse whether a combination of cosmic ray (CR) heating and thermal conduction can offset radiative cooling. To this end, we compile a large sample of 39 cool core clusters and determine steady state solutions of the hydrodynamic equations that are coupled to the CR energy equation. We find solutions that match the observed density and temperature profiles for all our clusters well. Radiative cooling is balanced by CR heating in the cluster centres and by thermal conduction on larger scales, thus demonstrating the relevance of both heating mechanisms. Our mass deposition rates vary by three orders of magnitude and are linearly correlated to the observed star formation rates. Clusters with large mass deposition rates show larger cooling radii and require a larger radial extent of the CR injection function. Interestingly, our sample shows a continuous sequence in cooling properties: clusters hosting radio mini halos are characterised by the largest cooling radii, star formation and mass deposition rates in our sample and thus signal the presence of a higher cooling activity. The steady state solutions support the structural differences between clusters hosting a radio mini halo and those that do not.
Ruthenium complexes of substituted hydrazine: new solution- and solid-state binding modes.
Dabb, Serin L; Messerle, Barbara A; Otting, Gottfried; Wagler, Jörg; Willis, Anthony
2008-01-01
The methylhydrazine complex [Ru(NH(2)NHMe)(PyP)(2)]Cl(BPh(4)) (PyP=1-[2-(diphenylphosphino)ethyl]pyrazole) was synthesised by addition of methylhydrazine to the bimetallic complex [Ru(mu-Cl)(PyP)(2)](2)(BPh(4))(2). The methylhydrazine ligand of the ruthenium complex has two different binding modes: side-on (eta(2)-) when the complex is in the solid state and end-on (eta(1)-) when the complex is in solution. The solid-state structure of [Ru(PyP)(2)(NH(2)NHMe)]Cl(BPh(4)) was determined by X-ray crystallography. 2D NMR spectroscopic experiments with (15)N at natural abundance confirmed that in solution the methylhydrazine is bound to the metal centre by only the -NH(2) group and the ruthenium complex retains an octahedral conformation. Hydrazine complexes [RuCl(PyP)(2)(eta(1)-NH(2)NRR')]OSO(2)CF(3) (in which R=H, R'=Ph, R=R'=Me and NRR'=NC(5)H(10)) were formed in situ by the addition of phenylhydrazine, 1,1-dimethylhydrazine and N-aminopiperidine, respectively, to a solution of the bimetallic complex [Ru(mu-Cl)(PyP)(2)](2)(OSO(2)CF(3))(2) in dichloromethane. These substituted hydrazine complexes of ruthenium were shown to exist in an equilibrium mixture with the bimetallic starting material.
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
NASA Astrophysics Data System (ADS)
Pei, Yongquan; Sun, Jitao
2016-11-01
This paper investigates the stationary average consensus problem for second-order discrete-time multi-agent systems (SDMAS). A stationary consensus problem is to find a control algorithm that brings the state of a group of agents to a common constant value which is called the collective decision. We introduce the concept of stationary average consensus of SDMAS and propose a consensus algorithm. Based on the polynomial stability and the graph theory, we obtain two necessary and sufficient conditions of stationary average consensus of SDMAS. The last theorem provides an algebraic criterion of stationary average consensus, and can help us to determine the parameters in the consensus algorithm. Furthermore, in this consensus algorithm, only the states of the agents are transferred among the agents. Therefore, this algorithm can not only solve the stationary average consensus problem but also reduce the amount of transferred data. A numerical example is provided to illustrate the efficiency of our results.
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
Refractive index and equation of state of a shock-compressed aqueous solution of zinc chloride
NASA Astrophysics Data System (ADS)
Wise, J. L.
1983-06-01
Velocity interferometers measurements have yielded refractive index and Hugoniot equation-of-state data for a 9.1-molar aqueous solution of zinc chloride which was shock-compressed to initial stresses ranging from 2.2 to 24.1 GPa in a series of plate-impact experiments. The Hugoniot data are accurately described by a linear variation of shock velocity with particle velocity. The optical data verify sustained solution transparency over the investigated range of shock stresses, and provide a calibration of the correction which must be applied to interferometer measurements to account for the stress-induced change in refractive index of the material. Refractive index data derived from the measured particle velocity corrections exhibit a departure from predictions based on the Gladstone-Dale relation.
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.
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.
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.
NASA Astrophysics Data System (ADS)
Nagy, M. I.; Csörgő, T.
2016-12-01
We present a class of analytic solutions of nonrelativistic fireball hydrodynamics for a fairly general class of equation of state. The presented solution describes the expansion of a triaxial ellipsoid that rotates around one of its principal axes. We calculate the hadronic final state observables such as single-particle spectra, directed, elliptic, and third flows, as well as two-particle Bose-Einstein (also named HBT) correlations and corresponding radius parameters, utilizing simple analytic formulas. The final tilt angle of the fireball, an important observable quantity, is shown to be not independent of its exact definition: one gets different tilt angles from the geometrical anisotropies, from the single-particle spectra, and from HBT measurements. Taken together, the tilt angle in the momentum space and in the relative momentum or HBT variable may be sufficient for the determination of the magnitude of the rotation of the fireball. We argue that observing this rotation and its dependence on collision energy could characterize the softest point of the equation of state. Thus determining the rotation may be a powerful tool for the experimental search for the critical point in the phase diagram of strongly interacting matter.
Unified semiclassical theory for the two-state system: Analytical solutions for scattering matrices
NASA Astrophysics Data System (ADS)
Zhu, Chaoyuan
1996-09-01
Unified semiclassical theory is established for general two-state system by employing an exactly analytical quantum solution [C. Zhu, J. Phys. A29, 1293 (1996)] for the Nikitin exponential-potential model which contains the two-state curve crossing and noncrossing cases as a whole. Analytical solutions for scattering matrices are found for both three- and two-channel cases within the time-independent treatment. This is made possible by introducing a very important parameter d(R0)=√)/[V22(R0)-V11(R0)]2 (V11(R), V22(R) and V12(R) are diabatic potentials and coupling, R0 is real part of complex crossing point between two adiabatic potentials) which represents a type of nonadiabatic transition for the two-state system. For instance, d=∞ represents the Landau-Zener type and d=√ represents Rosen-Zener type. Since d(R0) runs from unity to infinity, this parameter provides a quantitative description of nonadiabatic transition. The idea used here is the parameter comparison method which makes a unique link between the model and general potential system at the complex crossing point. This method is testified not only by numerical examples, but also by agreement of the present semiclassical formulas with all existing semiclassical formulas.
Santa María, Dolores; Claramunt, Rosa M; Alkorta, Ibon; Elguero, José
2009-06-01
The structure of the hypoglycemic agent Gliclazide has been studied by (1)H, (13)C, and (15)N NMR in solution (CDCl(3) and DMSO-d(6)) and in the solid state. In the solid state, the compound crystallizes as an EZ isomer without dynamic properties. In CDCl(3) solution, the structure is still EZ but with a slow nitrogen inversion about the pyrrolidine nitrogen: two invertomers have been observed and characterized. In DMSO-d(6), the rate is faster and only averaged signals were observed. GIAO calculated absolute shieldings were used to confirm the nature of the observed species. In the solid state, Gliclazide presents the phenomenon of solid-solution with two disordered conformations present in the crystal at a 90:10 ratio.
NASA Astrophysics Data System (ADS)
Galić, Nives; Brođanac, Ivan; Kontrec, Darko; Miljanić, Snežana
2013-04-01
Structural forms of aroylhydrazones derived from nicotinic acid hydrazide have been studied in the solid state by FT-IR spectroscopy and in solution by NMR, UV-Vis and ATR spectroscopy. The studied compounds were N'-benzylidene-3-pyridinecarbohydrazide (1), N'-(2,4-dihydroxyphenylmethylidene)-3-pyridinecarbohydrazide (2), N'-(5-chloro-2-hydroxyphenylmethylidene)-3-pyridinecarbohydrazide (3), and N'-(3,5-dichloro-2-hydroxymethoxyphenylmethylidene)-3-pyridinecarbohydrazide (4). The compound 1 adopted the most stable ketoamine form (form I, sbnd COsbnd NHsbnd Ndbnd Csbnd ) in the solid state as well as in various organic solvents. In mixtures of organic solvents with water the UV-Vis and ATR spectra implied intermolecular hydrogen bonding of 1 with water molecules. The presence of both tautomeric forms I and II (form II, sbnd COHdbnd Nsbnd Ndbnd Csbnd ) was proposed for the solid substance and highly concentrated solutions of 2, whereas form I was detected as the predominant one in diluted solutions. For compounds 3 and 4 a coexistence of forms I and III (form III, sbnd COsbnd NHsbnd NHsbnd Cdbnd Csbnd COsbnd ) was noticed in the solid state and in polar protic organic solvents. The conversion to form III was induced by increasing the water content in the solvent mixtures. This process was the most pronounced for compound 4. When exposed to daylight, an appearance of a new band was observed during time in the UV-Vis spectrum of 4 in organic solvent/water 1/1 mixtures, which implied that tautomeric interconversion was most likely followed by E/Z isomerisation.
The physical state of nafcillin sodium in frozen aqueous solutions and freeze-dried powders.
Milton, N; Nail, S L
1996-10-01
The purpose of this study was to develop a better understanding of the physical chemistry of freeze drying of lyotropic liquid crystals using nafcillin sodium as a model solute. Solutions and freeze-dried powders of nafcillin sodium were studied by polarized light microscopy, differential scanning calorimetry, x-ray powder diffraction, and water vapor adsorption. Differential scanning calorimetry thermograms of nafcillin sodium solutions contain a melting endotherm at approximately -5.5 degrees C and, depending on the concentration and heating rate, a crystallization exotherm immediately after this endotherm followed by the melting endotherm of ice. When the sample is annealed at -4 degrees C, both the endotherm and exotherm are eliminated, and a new endotherm appears at approximately -1 degree C on the shoulder of the ice-melting endotherm. The data are interpreted as melting of a liquid crystalline phase, followed by crystallization. X-ray powder diffractograms of unannealed freeze-dried nafcillin sodium are consistent with a lamellar liquid crystal. Diffractograms of annealed freeze-dried nafcillin sodium indicate crystalline material which is a different crystal form than the monohydrate starting material. Moisture adsorption isotherms of the freeze-dried annealed (crystalline) and unannealed (liquid crystalline) nafcillin sodium show different affinities for moisture compared to the crystalline starting material. Solid-state stability data demonstrate that the freeze-dried liquid crystalline form of nafcillin sodium is much less stable than the freeze-dried crystal-line material. The literature recognizes two types of solute behavior on freezing, where the solute either crystallizes from the freeze concentrate or remains amorphous. Lyotropic liquid crystal formation during freezing represents a separate category of freezing behavior, the physical chemistry of which is worthy of further investigation.
NASA Astrophysics Data System (ADS)
Urayama, Kenji; Kawamura, Takanobu; Kohjiya, Shinzo
1996-09-01
We have investigated the degree of equilibrium swelling and the elastic modulus of networks prepared by end-linking oligo(dimethylsiloxane)s (ODMS) in solution as a function of polymer concentration at crosslinking. The molecular weight of ODMS is so low that entanglement couplings are not formed in uncrosslinked state. It has been found from the preparation concentration dependence of elastic modulus in preparation state that trapped entanglements are formed by the introduction of crosslinks, and those considerably contribute to elastic modulus, even if the prepolymers are not entangled in uncrosslinked state. The experimental results for preparation concentration dependence of the degree of equilibrium swelling and the elastic modulus of equilibrium swollen networks are compared with the theoretical predictions by the two theories, i.e., the affine model and the c* theorem. It has been clearly shown that the affine model describes well the experimental results, while the discrepancies between the experimental results and the predictions by the c* theorem are considerable. These results strongly suggest that preparation concentration should be regarded as a reference state, and the displacement of crosslinks moves affinely on swelling, while the complete disinterpenetration of network chains in equilibrium swollen state, which is a postulate of the c* theorem, does not occur.
Synthesis of dental enamel-like hydroxyapatite through solution mediated solid-state conversion.
Zhang, Junling; Jiang, Dongliang; Zhang, Jingxian; Lin, Qingling; Huang, Zhengren
2010-03-02
An ordered dental enamel-like structure of hydroxyapatite (HAp) was achieved through a solution mediated solid-state conversion process with organic phosphate surfactant and gelatin as the mediating agent. Transmission electron microscopy (TEM) tests demonstrated uniform sizes in the obtained apatite nanorods which arranged in parallel to each other along the c-axis and formed organized microarchitectural units over 10 microm in size. The sizes of the synthetic hydroxyapatite nanorods were similar to that observed in enamel from human teeth. The formation and regulation of the orientation and size of HAp nanorods might lead to a better understanding of the biomineralization process for the preparation of high performance biomaterials.
Self-regulating genes. Exact steady state solution by using Poisson representation
NASA Astrophysics Data System (ADS)
Sugár, István P.; Simon, István
2014-09-01
Systems biology studies the structure and behavior of complex gene regulatory networks. One of its aims is to develop a quantitative understanding of the modular components that constitute such networks. The self-regulating gene is a type of auto regulatory genetic modules which appears in over 40% of known transcription factors in E. coli. In this work, using the technique of Poisson Representation, we are able to provide exact steady state solutions for this feedback model. By using the methods of synthetic biology (P.E.M. Purnick and Weiss, R., Nature Reviews, Molecular Cell Biology, 2009, 10: 410-422) one can build the system itself from modules like this.
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
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.
Carbon-dot organic surface modifier analysis by solution-state NMR spectroscopy
NASA Astrophysics Data System (ADS)
Philippidis, Aggelos; Spyros, Apostolos; Anglos, Demetrios; Bourlinos, Athanasios B.; Zbořil, Radek; Giannelis, Emmanuel P.
2013-07-01
Carbon dots (C-dots) represent a new class of carbon-based materials that were discovered recently and have drawn the interest of the scientific community, particularly because of their attractive optical properties and their potential as fluorescent sensors. Investigation of the chemical structure of C-dots is extremely important for correlating the surface modifier composition with C-dot optical properties and allow for structure-properties fine tuning. In this article, we report the structural analysis of the surface modifiers of three different types of C-dot nanoparticles (Cwax, Cws, and Csalt) by use of 1D- and 2D-high-resolution NMR spectroscopy in solution. We unambiguously verify that the structure of the modifier chains remains chemically unchanged during the passivation procedure, and confirm the covalent attachment of the modifiers to the nanoparticle core, which contributes no signal to the solution-state NMR spectra. To our knowledge, this is the first study confirming the full structural assignment of C-dot organic surface modifiers by use of solution NMR spectroscopy.
Steady state analytical solutions for pumping in a fully bounded rectangular aquifer
NASA Astrophysics Data System (ADS)
Lu, Chunhui; Xin, Pei; Li, Ling; Luo, Jian
2015-10-01
Using the Schwartz-Christoffel conformal mapping method together with the complex variable techniques, we derive steady state analytical solutions for pumping in a rectangular aquifer with four different combinations of impermeable and constant-head boundaries. These four scenarios include: (1) one constant-head boundary and three impermeable boundaries, (2) two pairs of orthogonal impermeable and constant-head boundaries, (3) three constant-head boundaries and one impermeable boundary, and (4) four constant-head boundaries. For these scenarios, the impermeable and constant-head boundaries can be combined after applying the mapping functions, and hence only three image wells exist in the transformed plane, despite an infinite number of image wells in the real plane. The closed-form solutions reflect the advantage of the conformal mapping method, though the method is applicable for the aspect ratio of the rectangle between 1/10.9 and 10.9/1 due to the limitation in the numerical computation of the conformal transformation from a half plane onto an elongated region (i.e., so-called "crowding" phenomenon). By contrast, for an additional scenario with two parallel constant-head boundaries and two parallel impermeable boundaries, an infinite series of image wells is necessary to express the solution, since it is impossible to combine these two kinds of boundaries through the conformal transformation. The usefulness of the results derived is demonstrated by an application to pumping in a finite coastal aquifer.
2013-01-01
Background Several papers described the structure of curcumin and some other derivatives in solid and in solution. In the crystal structure of curcumin, the enol H atom is located symmetrically between both oxygen atoms of the enolone fragment with an O···O distance of 2.455 Å, which is characteristic for symmetrical H-bonds. In the solution, the geometry of the enolone fragment is attributed to the inherent disorder of the local environment, which solvates one of the basic sites better than the other, stabilizing one tautomer over the other. In this paper, how the position of methoxy groups in dimethoxy curcuminoids influence the conformation of molecules and how the halogen atoms change it when they are bonded at α-position in keto-enol part of molecules is described. Results Six isomers of dimethoxy curcuminoids were prepared. Conformations in solid state, which were determined by X-ray single crystallography and 1H MAS and 13C CPMAS NMR measurements, depend on the position of methoxy groups in curcuminoid molecules. In solution, a fast equilibrium between both keto-enol forms exists. A theoretical calculation finding shows that the position of methoxy groups changes the energy of HOMO and LUMO. An efficient protocol for the highly regioselective bromination and chlorination leading to α-halogenated product has been developed. All α-halogenated compounds are present mainly in cis keto-enol form. Conclusions The structures in solid state of dimethoxy curcuminoids depend on the position of methoxy groups. The NMR data of crystalline solid samples of 3,4-diOCH3 derivative, XRD measurements and X-ray structures lead us to the conclusion that polymorphism exists in solids. The same conclusion can be done for 3,5-diOCH3 derivative. In solution, dimethoxy curcuminoids are present in the forms that can be described as the coexistence of two equivalent tautomers being in fast equilibrium. The position of methoxy groups has a small influence on the enolic hydrogen
Jungbauer, Stefan H; Schindler, Severin; Herdtweck, Eberhardt; Keller, Sandro; Huber, Stefan M
2015-09-21
The binding properties of neutral halogen-bond donors (XB donors) bearing two multidentate Lewis acidic motifs toward halides were investigated. Employing polyfluorinated and polyiodinated terphenyl and quaterphenyl derivatives as anion receptors, we obtained X-ray crystallographic data of the adducts of three structurally related XB donors with tetraalkylammonium chloride, bromide, and iodide. The stability of these XB complexes in solution was determined by isothermal titration calorimetry (ITC), and the results were compared to X-ray analyses as well as to calculated binding patterns in the gas phase. Density functional theory (DFT) calculations on the gas-phase complexes indicated that the experimentally observed distortion of the XB donors during multiple multidentate binding can be reproduced in 1:1 complexes with halides, whereas adducts with two halides show a symmetric binding pattern in the gas phase that is markedly different from the solid state structures. Overall, this study demonstrates the limitations in the transferability of binding data between solid state, solution, and gas phase in the study of complex multidentate XB donors.
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.
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.
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.
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.
Kim, Myoung-Ho; Choi, Suk-Jung
2015-04-15
In this study, we devised a stationary liquid-phase lab-on-a-chip (SLP LOC), which was operated by moving solid-phase magnetic particles in the stationary liquid phase. The SLP LOC consisted of a sample chamber to which a sample and reactants were added, a detection chamber containing enzyme substrate solution, and a narrow channel connecting the two chambers and filled with buffer. As a model system, competitive immunoassays of saxitoxin (STX), a paralytic shellfish toxin, were conducted in the SLP LOC using protein G-coupled magnetic particles (G-MPs) as the solid phase. Anti-STX antibodies, STX-horseradish peroxidase conjugate, G-MPs, and a STX sample were added to the sample chamber and reacted by shaking. While liquids were in the stationary state, G-MPs were transported from the sample chamber to the detection chamber by moving a magnet below the LOC. After incubation to allow the enzymatic reaction to occur, the absorbance of the detection chamber solution was found to be reciprocally related to the STX concentration of the sample. Thus, the SLP LOC may represent a novel, simple format for point-of-care testing applications of enzyme-linked immunosorbent assays by eliminating complicated liquid handling steps.
Stationary through-flows in a Bose-Einstein condensate with a PT -symmetric impurity
NASA Astrophysics Data System (ADS)
Zezyulin, Dmitry A.; Barashenkov, I. V.; Konotop, Vladimir V.
2016-12-01
Superfluid currents in the boson condensate with a source and sink of particles are modeled by the PT -symmetric Gross-Pitaevskii equation with a complex potential. We demonstrate the existence of through-flows of the condensate—stationary states with the asymptotically nonvanishing flux. The through-flows come in two broad varieties determined by the form of their number density distribution. One variety is described by diplike solutions featuring a localized density depression; the other one comprises humplike structures with a density spike in their core. We exemplify each class by exact closed-form solutions. For a fixed set of parameters of the PT -symmetric potential, stationary through-flows form continuous families parametrized by the strength of the background flux. All humplike and some diplike members of the family are found to be stable. We show that the through-flows can be controlled by varying the gain-and-loss amplitude of the complex potential and that these amplitude variations may produce an anomalous response of the flux across the gain-loss interface.
A Solution Space for a System of Null-State Partial Differential Equations: Part 1
NASA Astrophysics Data System (ADS)
Flores, Steven M.; Kleban, Peter
2015-01-01
This article is the first 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). In CFT, these are null-state equations and conformal Ward identities. They govern partition functions for the continuum limit of a statistical cluster or loop-gas model, such as percolation, or more generally the Potts models and O( n) models, at the statistical mechanical critical point. (SLE partition functions also satisfy these equations.) For such a lattice model in a polygon with its 2 N sides exhibiting a free/fixed side-alternating boundary condition , this partition function is proportional to the CFT correlation function where the w i are the vertices of and where is a one-leg corner operator. (Partition functions for "crossing events" in which clusters join the fixed sides of in some specified connectivity are linear combinations of such correlation functions.) When conformally mapped onto the upper half-plane, methods of CFT show that this correlation function satisfies the system of PDEs that we consider. In this first article, we use methods of analysis to prove that the dimension of this solution space is no more than C N , the Nth Catalan number. While our motivations are based in CFT, our proofs are completely rigorous. This proof is contained entirely within this article, except for the proof of Lemma 14, which constitutes the second article (Flores and Kleban, in Commun Math Phys, arXiv:1404.0035, 2014). In the third article (Flores and Kleban, in Commun Math Phys, arXiv:1303.7182, 2013), we use the results of this article to prove that the solution space of this system of PDEs has dimension C N and is spanned by solutions constructed with the CFT Coulomb gas (contour integral) formalism. In the fourth article (Flores and Kleban, in Commun Math Phys, arXiv:1405
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.
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...
INCA: a computational platform for isotopically non-stationary metabolic flux analysis.
Young, Jamey D
2014-05-01
13C flux analysis studies have become an essential component of metabolic engineering research. The scope of these studies has gradually expanded to include both isotopically steady-state and transient labeling experiments, the latter of which are uniquely applicable to photosynthetic organisms and slow-to-label mammalian cell cultures. Isotopomer network compartmental analysis (INCA) is the first publicly available software package that can perform both steady-state metabolic flux analysis and isotopically non-stationary metabolic flux analysis. The software provides a framework for comprehensive analysis of metabolic networks using mass balances and elementary metabolite unit balances. The generation of balance equations and their computational solution is completely automated and can be performed on networks of arbitrary complexity.
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
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.
Analysis of lasers as a solution to efficiency droop in solid-state lighting
NASA Astrophysics Data System (ADS)
Chow, W. W.; Crawford, M. H.
2015-10-01
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. A solution to some of these concerns is suggested that takes advantage of recent developments in nanolasers.
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.
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
Stranius, K.; Börjesson, K.
2017-01-01
Photoswitchable molecules are able to isomerize between two metastable forms through light stimuli. Originally being studied by photochemists, this type of molecule has now found a wide range of applications within physics, chemistry and biology. The extensive usage of photochromic molecules is due to the two isomers having fundamentally different physical and chemical properties. The most important attribute of a photoswitch is the photoisomerization quantum yield, which defines the efficiency of the photoisomerization event. Here we show how to determine the photoisomerization quantum yield in the solid state and in solution when taking thermal processes into account. The described method together with provided software allows for rapid and accurate determination of the isomerization process for this important class of molecules. PMID:28117426
NASA Astrophysics Data System (ADS)
Stranius, K.; Börjesson, K.
2017-01-01
Photoswitchable molecules are able to isomerize between two metastable forms through light stimuli. Originally being studied by photochemists, this type of molecule has now found a wide range of applications within physics, chemistry and biology. The extensive usage of photochromic molecules is due to the two isomers having fundamentally different physical and chemical properties. The most important attribute of a photoswitch is the photoisomerization quantum yield, which defines the efficiency of the photoisomerization event. Here we show how to determine the photoisomerization quantum yield in the solid state and in solution when taking thermal processes into account. The described method together with provided software allows for rapid and accurate determination of the isomerization process for this important class of molecules.
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.
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.
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.
Kinetic properties of tetrameric glycogen phosphorylase b in solution and in the crystalline state.
Leonidas, D. D.; Oikonomakos, N. G.; Papageorgiou, A. C.; Sotiroudis, T. G.
1992-01-01
R-state monoclinic P2(1) crystals of phosphorylase have been shown to be catalytically active in the presence of an oligosaccharide primer and glucose-1-phosphate in 0.9 M ammonium sulfate, 10 mM beta-glycerophosphate, 0.5 mM EDTA, and 1 mM dithiothreitol, the medium in which the crystals are grown or equilibrated for crystallographic studies (Barford, D. & Johnson, L.N., 1989, Nature 360, 609-616; Barford, D., Hu, S.-H., & Johnson, L.N., 1991, J. Mol. Biol. 218, 233-260). Kinetic data suggest that the activity of crystalline tetrameric phosphorylase is similar to that determined in solution for the enzyme tetramer. However, large differences were found in the maximal velocities for both oligosaccharide or glucose-1-phosphate substrates between the soluble dimeric and crystalline tetrameric enzyme. PMID:1304391
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
State of the art and recent development of embedded network solutions research
NASA Astrophysics Data System (ADS)
Gillet, Michel; Balandin, Sergey
2008-04-01
Recently we could observe a huge change in the mobile industry when the original idea of mobile phone was transformed into the new concept of mobile multimedia devices capable to perform multiple complex tasks and integrating a number of functionalities. As a consequence it resulted in significant increase of the device integration time and cost and complicated deployment of the new technologies. The device integrators are forced to favor modularity everywhere where it is possible in design of new devices, which results in a new trend towards networked architectures for the mobile devices. However, moving towards networked architectures specifically designed to overcome limitations brought by the mobile devices is a time consuming task. It requires fresh mind analysis of many solutions applied in other contexts, since some of the constraints and requirements are unique in comparison with e.g. SoC, NoC, which are the most known embedded network solutions, and of course they are significantly different comparing to the wide area networks. The main differentiating factors are: strongly constrained power consumption by the battery life time; and a need for modular architecture to allow reuse of the existing components or modules. The paper provides an overview of the state of art in the embedded networks research and describes general background for our studies, key assumptions, restrictions and limitations that we faced at the beginning of development of the embedded networks architecture for mobile devices.
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
State of the Art in LP-WAN Solutions for Industrial IoT Services.
Sanchez-Iborra, Ramon; Cano, Maria-Dolores
2016-05-17
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.
NASA Astrophysics Data System (ADS)
Brooks, C. L., III; Balk, M. W.; Adelman, S. A.
1983-07-01
The dynamics of vibrational energy relaxation of highly excited molecular iodine in three monatomic solvents is studied via stochastic classical trajectory simulations based on the molecular timescale generalized Langevin equation (MTGLE) of motion for liquid state chemical reactions [S. A. Adelman, J. Chem. Phys. 73, 3145 (1980)]. Also presented for comparison purposes are parallel studies based on a matrix Langevin equation of motion characterized by friction coefficients which depend on the instantaneous I2 internuclear separation R. The qualitative features of the energy relaxation may be interpreted as effects arising from modifications of the solute dynamics due to molecular timescale correlations between its motion and that of its solvation shells. Such dynamical solvent effects are realistically described by the MTGLE equation of motion but not by the Langevin equation. Thus, for example, the marked slowdown of the rate of I2 energy relaxtion in simple solvents when the I2 vibrational quantum number drops below a solvent-dependent critical value, earlier predicted by Nesbitt and Hynes, is predicted by MTGLE dynamics but not by Langevin dynamics. Finally, practical algorithms for numerically constructing the MTGLE and Langevin equations for specific solute-solvent systems are presented.
Enhanced Conformational Sampling of N-glycans in Solution with Replica State Exchange Metadynamics.
Galvelis, Raimondas; Re, Suyong; Sugita, Yuji
2017-04-11
Molecular dynamics (MD) simulation of a N-glycan in solution is challenging due to high- energy barriers of the glycosidic linkages, functional group rotational barriers, and numerous intra- and inter-molecular hydrogen bonds. In this study, we apply different enhanced conformational sampling approaches, namely, metadynamics (MTD), the replica-exchange MD (REMD), and the recently proposed replica state exchange MTD (RSE-MTD), to a N-glycan in solution and compare their conformational sampling efficiencies. MTD helps to cross the high- energy barrier along the ω angle by utilizing a bias potential, but it cannot enhance sampling of the other degrees of freedom. REMD ensures moderate-energy barrier crossings by exchanging temperatures between replicas, while it hardly crosses the barriers along ω. In contrast, RSE- MTD succeeds to cross the high-energy barrier along ω as well as to enhance sampling of the other degrees of freedom. We tested two RSE-MTD schemes: in one scheme, 64 replicas were simulated with the bias potential along ω at different temperatures, while simulations of 4 replicas were performed with the bias potentials for different CVs at 300 K. In both schemes, one unbiased replica at 300 K was included to compute conformational properties of the glycan. The conformational sampling of the former is better than the other enhanced sampling methods, while the latter shows reasonable performance without spending large computational resources. The latter scheme is likely to be useful when a N-glycan-attached protein is simulated.
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
NASA Astrophysics Data System (ADS)
Pradhan, Tuhin; Gazi, Harun Al Rasid; Biswas, Ranjit
2009-08-01
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 (LiClO4) 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 (-ΔGr) 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, LiClO4 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 (-ΔGr), the former in ethanol and ACN increases only linearly with the increase in driving force (-ΔGr). 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.
Stationary and transient Soret separation in a binary mixture with a consolute critical point.
Ryzhkov, Ilya I; Kozlova, Sofia V
2016-12-01
The stationary and transient Soret separation in a binary mixture with a consolute critical point is studied theoretically. The mixture is placed between two parallel plates kept at different temperatures. A polymer blend is used as a model system. Analytical solutions are constructed to describe the stationary separation in a binary mixture with variable Soret coefficient. The latter strongly depends on temperature and concentration and enhances near a consolute critical point due to reduced diffusion. As a result, a large concentration gradient is observed locally, while much smaller concentration variations are found in the rest of the layer. It is shown that complete separation can be obtained by applying a small temperature difference first, waiting for the establishment of stationary state, and then increasing this difference again. In this case, the critical temperature lies between hot and cold wall temperatures, while the mixture still remains in the one-phase region. When the initial (mean) temperature or concentration are shifted away from the near-critical values, the separation decreases. The analysis of transient behavior shows that the Soret separation occurs much faster than diffusion to the homogeneous state when the initial concentration is close to the critical one. It happens due to the decrease (increase) of the local relaxation time during the Soret (Diffusion) steps. The transient times of these steps become comparable for small temperature differences or off-critical initial concentrations. An unusual (non-exponential) separation dynamics is observed when the separation starts in the off-critical domain, and then enhances greatly when the system enters into the near-critical region. It is also found that the transient time decreases with increasing the applied temperature difference.
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
Unprecedented synthesis of 1,3-dimethylcyclobutadiene in the solid state and aqueous solution.
Legrand, Yves-Marie; Gilles, Arnaud; Petit, Eddy; van der Lee, Arie; Barboiu, Mihail
2011-08-29
Cyclobutadiene (CBD), the smallest cyclic hydrocarbon bearing conjugated double bonds, has long intrigued chemists because of its chemical characteristics. The question of whether the molecule could be prepared at all has been answered, but the parent compound and its unperturbed derivatives have eluded crystallographic characterization or synthesis "in water". Different approaches have been used to generate and to trap cyclobutadiene in a variety of confined environments: a) an Ar matrix at cryogenic temperatures, b) a hemicarcerand cage enabling the characterization by NMR spectroscopy in solution, and c) a crystalline guanidinium-sulfonate-calixarene G(4)C matrix that is stable enough to allow photoreactions in the solid state. In the latter case, the 4,6-dimethyl-α-pyrone precursor, Me(2)1, has been immobilized in a guanidinium-sulfonate-calixarene G(4)C crystalline network through a combination of non-covalent interactions. UV irradiation of the crystals transforms the entrapped Me(2)1 into a 4,6-dimethyl-Dewar-β-lactone intermediate, Me(2)2, and rectangular-bent 1,3-dimethylcyclobutadiene, Me(2)CBD(R), which are sufficiently stable under the confined conditions at 175 K to allow a conventional structure determination by X-ray diffraction. Further irradiation drives the reaction towards Me(2)3&Me(2)CBD(S)/CO(2) (63.7 %) and Me(2)CBD(R) (37.3 %) superposed crystalline architectures and the amplification of Me(2)CBD(R). The crystallographic models are supported by additional FTIR and Raman experiments in the solid state and by (1)H NMR spectroscopy and ESI mass spectrometry experiments in aqueous solution. Amazingly, the 4,6-dimethyl-Dewar-β-lactone, Me(2)2, the cyclobutadiene-carboxyl zwitterion, Me(2)3, and 1,3-dimethylcyclobutadiene, Me(2)CBD, were obtained by ultraviolet irradiation of an aqueous solution of G(4)C{Me(2)1}. 1,3-Dimethylcyclobutadiene is stable in water at room temperature for several weeks and even up to 50 °C as demonstrated by
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.
NASA Astrophysics Data System (ADS)
Trendafilova, N.; Kellner, R.
The IR spectra of zinc(II) bis-(N,N'-diethyldithiocarbamate) in the solid state (at 20, 80 and 120°C) as well as in solution (20°C) have been recorded and discussed as to the changes in the zinc coordination sphere that may occur upon heating and dissolution. The decreased number of bands in the high-temperature and in the solution specta as compared with the room temperature solid state spectra has been explained by removal of the intermolecular contacts upon dissolution or thermal averaging in the high temperature solid state.
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
Supramolecular stabilization of metastable tautomers in solution and the solid state.
Juribašić, Marina; Bregović, Nikola; Stilinović, Vladimir; Tomišić, Vladislav; Cindrić, Marina; Sket, Primož; Plavec, Janez; Rubčić, Mirta; Užarević, Krunoslav
2014-12-22
This work presents a successful application of a recently reported supramolecular strategy for stabilization of metastable tautomers in cocrystals to monocomponent, non-heterocyclic, tautomeric solids. Quantum-chemical computations and solution studies show that the investigated Schiff base molecule, derived from 3-methoxysalicylaldehyde and 2-amino-3-hydroxypyridine (ap), is far more stable as the enol tautomer. In the solid state, however, in all three obtained polymorphic forms it exists solely as the keto tautomer, in each case stabilized by an unexpected hydrogen-bonding pattern. Computations have shown that hydrogen bonding of the investigated Schiff base with suitable molecules shifts the tautomeric equilibrium to the less stable keto form. The extremes to which supramolecular stabilization can lead are demonstrated by the two polymorphs of molecular complexes of the Schiff base with ap. The molecules of both constituents of molecular complexes are present as metastable tautomers (keto anion and protonated pyridine, respectively), which stabilize each other through a very strong hydrogen bond. All the obtained solid forms proved stable in various solid-state and solvent-mediated methods used to establish their relative thermodynamic stabilities and possible interconversion conditions.
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.
Modeling of dielectric properties of aqueous salt solutions with an equation of state.
Maribo-Mogensen, Bjørn; Kontogeorgis, Georgios M; Thomsen, Kaj
2013-09-12
The static permittivity is the most important physical property for thermodynamic models that account for the electrostatic interactions between ions. The measured static permittivity in mixtures containing electrolytes is reduced due to kinetic depolarization and reorientation of the dipoles in the electrical field surrounding ions. Kinetic depolarization may explain 25-75% of the observed decrease in the permittivity of solutions containing salts, but since this is a dynamic property, this effect should not be included in the thermodynamic modeling of electrolytes. Kinetic depolarization has, however, been ignored in relation to thermodynamic modeling, and authors have either neglected the effect of salts on permittivity or used empirical correlations fitted to the measured static permittivity, leading to an overestimation of the reduction in the thermodynamic static permittivity. We present a new methodology for obtaining the static permittivity over wide ranges of temperatures, pressures, and compositions for use within an equation of state for mixed solvents containing salts. The static permittivity is calculated from a new extension of the framework developed by Onsager, Kirkwood, and Fröhlich to associating mixtures. Wertheim's association model as formulated in the statistical associating fluid theory is used to account for hydrogen-bonding molecules and ion-solvent association. Finally, we compare the Debye-Hückel Helmholtz energy obtained using an empirical model with the new physical model and show that the empirical models may introduce unphysical behavior in the equation of state.
Proton-transfer mediated quenching of pyrene/indole charge-transfer states in isooctane solutions.
Altamirano, Marcela S; Bohorquez, María del Valle; Previtali, Carlos M; Chesta, Carlos A
2008-01-31
The fluorescence quenching of pyrene (Py) by a series of N-methyl and N-H substituted indoles was studied in isooctane at 298 K. The fluorescence quenching rate constants were evaluated by mean of steady-state and time-resolved measurements. In all cases, the quenching process involves a charge-transfer (CT) mechanism. The I(o)/I and tau(o)/tau Stern-Volmer plots obtained for the N-H indoles show a very unusual upward deviation with increasing concentration of the quenchers. This behavior is attributed to the self-quenching of the CT intermediates by the free indoles in solution. The efficiency of quenching of the polyaromatic by the N-H indoles increases abruptly in the presence of small amount of added pyridine (or propanol). A detailed analysis of the experimental data obtained in the presence of pyridine provides unambiguous evidence that the self-quenching process involves proton transfer from the CT states to indoles.
A physical theory of the living state: application to water and solute distribution.
Ling, G N
1988-06-01
This review begins with a summary of the disproof of the membrane-pump theory and the alternative theory of the living cell, the association-induction (AI) hypothesis. Being alive in the AI hypothesis represents the maintenance of a high (negative) energy-low entropy state in which the two major components K+ and water of the living cell are closely associated with the third major component of the living cells, proteins. K+ is adsorbed singly on beta- and gamma- carboxyl groups and the bulk of cell water in multilayers on the exposed NHCO groups of fully extended polypeptide chains of cell proteins. These adsorptions account for both the constancy of cell K+ and cell water per unit of cell proteins. ATP plays a key role in the maintenance of the cooperatively linked protein-ion-water assembly at the living state by its adsorption on key protein site and exercises the controlling influence through its strong inductive effects. Water polarized in multilayers demonstrates size-dependent exclusion of solutes, e.g., large (hydrated) Na+ is excluded from water in living cells or model systems while smaller urea that fits into the dynamic water structure is not excluded. The confirmation of the polarized multilayer theory of cell water by nuclear magnetic resonance (NMR), dielectric, neutron scattering, and other studies not only reverses the conventional belief of the existence of the cell water as normal liquid water; it also gives a new definition to colloids.
Observation of a Zundel-like transition state during proton transfer in aqueous hydroxide solutions
Roberts, Sean T.; Petersen, Poul B.; Ramasesha, Krupa; Tokmakoff, Andrei; Ufimtsev, Ivan S.; Martinez, Todd J.
2009-01-01
It is generally accepted that the anomalous diffusion of the aqueous hydroxide ion results from its ability to accept a proton from a neighboring water molecule; yet, many questions exist concerning the mechanism for this process. What is the solvation structure of the hydroxide ion? In what way do water hydrogen bond dynamics influence the transfer of a proton to the ion? We present the results of femtosecond pump-probe and 2D infrared experiments that probe the O-H stretching vibration of a solution of dilute HOD dissolved in NaOD/D2O. Upon the addition of NaOD, measured pump-probe transients and 2D IR spectra show a new feature that decays with a 110-fs time scale. The calculation of 2D IR spectra from an empirical valence bond molecular dynamics simulation of a single NaOH molecule in a bath of H2O indicates that this fast feature is due to an overtone transition of Zundel-like H3O2− states, wherein a proton is significantly shared between a water molecule and the hydroxide ion. Given the frequency of vibration of shared protons, the observations indicate the shared proton state persists for 2–3 vibrational periods before the proton localizes on a hydroxide. Calculations based on the EVB-MD model argue that the collective electric field in the proton transfer direction is the appropriate coordinate to describe the creation and relaxation of these Zundel-like transition states. PMID:19666493
NASA Astrophysics Data System (ADS)
Kalinin, A. V.; Sumin, M. I.; Tyukhtina, A. A.
2017-02-01
An initial-boundary value problem for Maxwell's equations in the quasi-stationary magnetic approximation is investigated. Special gauge conditions are presented that make it possible to state the problem of independently determining the vector magnetic potential. The well-posedness of the problem is proved under general conditions on the coefficients. For quasi-stationary Maxwell equations, final observation problems formulated in terms of the vector magnetic potential are considered. They are treated as convex programming problems in a Hilbert space with an operator equality constraint. Stable sequential Lagrange principles are stated in the form of theorems on the existence of a minimizing approximate solution of the optimization problems under consideration. The possibility of applying algorithms of dual regularization and iterative dual regularization with a stopping rule is justified in the case of a finite observation error.
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.
Solution and Solid State Chemistry of Dimolybdenum Fluoroacetates with Ethylenediamine Derivatives
NASA Astrophysics Data System (ADS)
Snowden, Kevin Joseph
Reactions of Mo_2 (O_2 CCF_3)_4, Mo_2O _2CCHF_2)_4, and Mo _2(O_2 CCH_2 F)_4 with the diamines (N,N-dimethylethylene-diamine (udmed), N,N^'-dimethylethylenediamine (sdmed), and N,N,N^',N ^',-tetramethylethylenediamine (tmed)) have been studied. Mo_2(O_2 CCF_3) _4 reacts with udmed in ethanol or acetonitrile to form crystalline (Mo_2(O_2 CCF_3)_3(udmed)_2 ) -(O_2{CCF}_3 ). A single-crystal x-ray study of the orange blades indicate that the complex exists as an ion pair, in which the udmed ligands bind as axial-equatorial chelates to each of the metals. The structure contains hydrogen bonds between the Mo_2 (rm O_2{CCF}_3)_3(udmed) ^+ cation and the free CF_3 {CO}_2^- anion. The compound crystallizes in the monoclinc space group I2/a. The solution reactions of Mo_2( rm O_2{CCF}_3)_4 with udmed, sdmed, and tmed have been studied at -20^circC in ethanol/CD_3CN by ^ {19}F NMR spectroscopy, with Mo _2: diamine ratios up to 1: 8. Udmed displaces on average up to three bridging CF_3{CO}_2 groups from the Mo _2(rm O_2 {CF}_3) _4 core. Sdmed displaces all bridging CF _3{CO}_2 groups. Tmed forms products which on average have two bridging and two free CF_3{CO }_2 groups. The course of these reactions and possible structures of the products are discussed based on spectra and chemical observations. The complex Mo_2(rm O_2 {CCH}_2rm F)_4 reacts with udmed in ethanol to produce crystalline (Mo _2(rm O_2{CCH} _2rm F)_3(udmed)_2 ) -(O_2{CCH}_2 rm F). Solid-state IR establish and single -crystal x-ray studies of the chunky orange crystals show that this compound is much like the trifluoroacetate analogue. The compound crystallizes in monoclinic space group P2 _1/c. The solution reaction reactions of Mo _2(rm O_2{CCHF}_2) _4 with udmed, sdmed, and tmed have been studied at -20^circ C in ethanol/CD_3CN by ^{19}F NMR spectroscopy, with Mo _2: diamine ratios up to 1: 8. Udmed produces appreciable amount of nonbridging and free CHF _2{CO}_2 groups. Sdmed readily displaces all bridging
Georgieva, I; Trendafilova, N; Aquino, A; Lischka, H
2005-12-29
TDDFT/B3LYP and RI-CC2 calculations with different basis sets have been performed for vertical and adiabatic excitations and emission properties of the lowest singlet states for the neutral (enol and keto), protonated and deprotonated forms of 7-hydroxy-4-methylcoumarin (7H4MC) in the gas phase and in solution. The effect of 7H4MC-solvent (water) interactions on the lowest excited and fluorescence states were computed using the Polarizable Continuum Method (PCM), 7H4MC-water clusters and a combination of both approaches. The calculations revealed that in aqueous solution the pi pi* energy is the lowest one for excitation and fluorescence transitions of all forms of 7H4MC studied. The calculated excitation and fluorescence energies in aqueous solution are in good agreement with experiment. It was found that, depending on the polarity of the medium, the solvent shifts vary, leading to a change in the character of the lowest excitation and fluorescence transition. The dipole-moment and electron-density changes of the excited states relative to the ground state correlate with the solvation effect on the singlet excited states and on transition energies, respectively. The calculations show that, in contrast to the ground state, the keto form has a lower energy in the pi pi* state as compared to enol, demonstrating from this point of view the energetic possibility of proton transfer from the enol to the keto form in the excited state.
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
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
Ahmad, R.A.
1996-01-01
A numerical analysis of forced-convection heat transfer from a horizontal stationary circular cylinder dissipating a uniform heat flux in a crossflow of air is conducted by solving the full two-dimensional steady-state Navier-Stokes and energy equations in the range of the Reynolds numbers from 100 to 500 (based on diameter). A numerical study by this author for Reynolds numbers less than 100 was previously conducted and therefore is not repeated here. Dependence on the Reynolds number of the flow and thermal fields, vorticity and pressure distributions, separation angle, drag coefficient, and local and average Nusselt number around the cylinder are shown. Correlations for the separation angle and drag coefficient as functions of Reynolds number are suggested. Quantities such as vorticity, pressure, and Nusselt number at the forward and rear (base) stagnation points are also calculated and correlated as functions of Reynolds number. The local and average values of the Nusselt numbers are shown to be in good agreement with available correlations and experiments. The average forced-convection Nusselt number is correlated. A new correlation for the mean value of forced-convection Nusselt number based on 27 previous studies, including the present results, is proposed. Theoretical predictions and available experimental data are found to be in agreement. Theoretical prediction of the thermal field has no precedence. Flow control methods (which may be possible when turbulence is understood) to stabilize unstable solutions may lead to significant new classes of flows, which at first may be studied numerically more easily and cheaply. The extensive comparison and literature survey given in this article have shown that this fundamental problem is one of such continuing interest, at least from the perspective of fluid flow studies.
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.
Code of Federal Regulations, 2011 CFR
2011-07-01
... PLANS (CONTINUED) Ohio § 52.1889 Small business stationary source technical and environmental compliance assistance program. The Ohio program, submitted as a requested revision to the Ohio State Implementation...
Code of Federal Regulations, 2010 CFR
2010-07-01
... PLANS (CONTINUED) Ohio § 52.1889 Small business stationary source technical and environmental compliance assistance program. The Ohio program, submitted as a requested revision to the Ohio State Implementation...
Chen, Xiao-Yan; Goff, George S; Scott, Brian L; Janicke, Michael T; Runde, Wolfgang
2013-03-18
As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-1-yl)acetic acid (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-elements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = 5 and synthesized four lanthanide complexes of general formula [Ln(L)3(H2O)2]·nH2O (1, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = 1). All complexes were characterized by single crystal X-ray diffraction analysis revealing one-dimensional chain formations. Two distinct crystallographic structures are governed by the different coordination modes of carboxylate groups in L: terminal bidentate and bridging tridentate (1-3); terminal bidentate, bridging bidentate, and tridentate coordination in 4. Comparison of the solid state UV-vis-NIR diffuse reflectance spectra with solution state UV-vis-NIR spectra suggests a different species in solution and solid state. The different coordination in solid state and solution was verified by distinctive (13)C NMR signals of the carboxylate groups in the solid state NMR.
Wen, Xiao-Yong; Yan, Zhenya; Malomed, Boris A
2016-12-01
An integrable system of two-component nonlinear Ablowitz-Ladik equations is used to construct complex rogue-wave (RW) solutions in an explicit form. First, the modulational instability of continuous waves is studied in the system. Then, new higher-order discrete two-component RW solutions of the system are found by means of a newly derived discrete version of a generalized Darboux transformation. Finally, the perturbed evolution of these RW states is explored in terms of systematic simulations, which demonstrates that tightly and loosely bound RWs are, respectively, nearly stable and strongly unstable solutions.
NASA Astrophysics Data System (ADS)
Wen, Xiao-Yong; Yan, Zhenya; Malomed, Boris A.
2016-12-01
An integrable system of two-component nonlinear Ablowitz-Ladik equations is used to construct complex rogue-wave (RW) solutions in an explicit form. First, the modulational instability of continuous waves is studied in the system. Then, new higher-order discrete two-component RW solutions of the system are found by means of a newly derived discrete version of a generalized Darboux transformation. Finally, the perturbed evolution of these RW states is explored in terms of systematic simulations, which demonstrates that tightly and loosely bound RWs are, respectively, nearly stable and strongly unstable solutions.
A novel vehicle stationary detection utilizing map matching and IMU sensors.
Amin, Md Syedul; 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.
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
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.
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.
Two-lane traffic-flow model with an exact steady-state solution.
Kanai, Masahiro
2010-12-01
We propose a stochastic cellular-automaton model for two-lane traffic flow based on the misanthrope process in one dimension. The misanthrope process is a stochastic process allowing for an exact steady-state solution; hence, we have an exact flow-density diagram for two-lane traffic. In addition, we introduce two parameters that indicate, respectively, driver's driving-lane preference and passing-lane priority. Due to the additional parameters, the model shows a deviation of the density ratio for driving-lane use and a biased lane efficiency in flow. Then, a mean-field approach explicitly describes the asymmetric flow by the hop rates, the driving-lane preference, and the passing-lane priority. Meanwhile, the simulation results are in good agreement with an observational data, and we thus estimate these parameters. We conclude that the proposed model successfully produces two-lane traffic flow particularly with the driving-lane preference and the passing-lane priority.
Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Hu, Hanlin; Amassian, Aram
2016-08-03
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.
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...
A numerical approach to finding general stationary vacuum black holes
NASA Astrophysics Data System (ADS)
Adam, Alexander; Kitchen, Sam; Wiseman, Toby
2012-08-01
The Harmonic Einstein equation is the vacuum Einstein equation supplemented by a gauge fixing term which we take to be that of DeTurck. For static black holes analytically continued to Riemannian manifolds without boundary at the horizon, this equation has previously been shown to be elliptic, and Ricci flow and Newton’s method provide good numerical algorithms to solve it. Here we extend these techniques to the arbitrary cohomogeneity stationary case which must be treated in Lorentzian signature. For stationary spacetimes with globally timelike Killing vector the Harmonic Einstein equation is elliptic. In the presence of horizons and ergo-regions it is less obviously so. Motivated by the Rigidity theorem we study a class of stationary black hole spacetimes which is general enough to include many interesting higher dimensional solutions. We argue the Harmonic Einstein equation consistently truncates to this class of spacetimes giving an elliptic problem. The Killing horizons and axes of rotational symmetry are boundaries for this problem and we determine boundary conditions there. As a simple example we numerically construct 4D rotating black holes in a cavity using Anderson’s boundary conditions. We demonstrate both Newton’s method and Ricci flow to find these Lorentzian solutions.
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
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.
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…
Grollman, A
1931-05-20
DATA FOR THE DEPRESSION OF VAPOUR PRESSURE ARE PRESENTED FOR THE FOLLOWING AQUEOUS SOLUTIONS: NaCl (0.03 to 0.1 molar), KCl (0.03 to 0.1 molar), urea (0.05 to 0.5 molar), sucrose (0.05 to 0.10 molar), lactic and succinic acids, creatine, CaCl(2) (0.05 molar), and mixtures of these substances with one another and with certain other solutions (gelatin, gum acacia, sea water, LiCl, etc.). The relation of the depression of vapour pressure of a mixed solution to that of solutions of the individual constituents was investigated in order to ascertain to what extent such studies may be used for the determination of the degree of hydration, or of the state of water, in solutions. Organic substances (urea, sucrose, etc.) showed anomalous results which were markedly affected and unpredictable in mixed solutions. They are, therefore, unsuited for the study of water binding. In the case of solutions of inorganic substances-LiCl and CaCl(2)-the principle of the additive nature of colligative properties is also only approximately true-except perhaps in very dilute solutions. The limitations of the colligative method for determining the degree of hydration have been defined in accord with the above findings. Studies of the vapour pressures of mixtures of gelatin or gum acacia with NaCl or KCl demonstrated that hydration in gelatin is relatively small at pH = 7 and undetectable in gum acacia solutions. The view, therefore, that hydrophilic colloids are strongly hydrated has not been substantiated. The passage from the sol to the gel state also was not accompanied in gelatin or in blood by any appreciable change in the degree of hydration of the hydrophilic colloids present in these substances.
Grollman, Arthur
1931-01-01
Data for the depression of vapour pressure are presented for the following aqueous solutions: NaCl (0.03 to 0.1 molar), KCl (0.03 to 0.1 molar), urea (0.05 to 0.5 molar), sucrose (0.05 to 0.10 molar), lactic and succinic acids, creatine, CaCl2 (0.05 molar), and mixtures of these substances with one another and with certain other solutions (gelatin, gum acacia, sea water, LiCl, etc.). The relation of the depression of vapour pressure of a mixed solution to that of solutions of the individual constituents was investigated in order to ascertain to what extent such studies may be used for the determination of the degree of hydration, or of the state of water, in solutions. Organic substances (urea, sucrose, etc.) showed anomalous results which were markedly affected and unpredictable in mixed solutions. They are, therefore, unsuited for the study of water binding. In the case of solutions of inorganic substances—LiCl and CaCl2—the principle of the additive nature of colligative properties is also only approximately true—except perhaps in very dilute solutions. The limitations of the colligative method for determining the degree of hydration have been defined in accord with the above findings. Studies of the vapour pressures of mixtures of gelatin or gum acacia with NaCl or KCl demonstrated that hydration in gelatin is relatively small at pH = 7 and undetectable in gum acacia solutions. The view, therefore, that hydrophilic colloids are strongly hydrated has not been substantiated. The passage from the sol to the gel state also was not accompanied in gelatin or in blood by any appreciable change in the degree of hydration of the hydrophilic colloids present in these substances. PMID:19872614
Model of non-stationary, inhomogeneous turbulence
Bragg, Andrew D.; Kurien, Susan; Clark, Timothy T.
2016-07-08
Here, 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 longmore » 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.« less
Model of non-stationary, inhomogeneous turbulence
Bragg, Andrew D.; Kurien, Susan; Clark, Timothy T.
2016-07-08
Here, 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.
Model of non-stationary, inhomogeneous turbulence
NASA Astrophysics Data System (ADS)
Bragg, Andrew D.; Kurien, Susan; Clark, Timothy T.
2017-02-01
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.
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.
Analytical solutions for the spin-1 Bose-Einstein condensate in a harmonic trap
NASA Astrophysics Data System (ADS)
Shi, Yu-Ren; Wang, Xue-Ling; Wang, Guang-Hui; Liu, Cong-Bo; Zhou, Zhi-Gang; Yang, Hong-Juan
2013-06-01
The homotopy analysis method and Galerkin spectral method are applied to find the analytical solutions for the Gross-Pitaevskii equations, a set of nonlinear Schrödinger equation used in simulation of spin-1 Bose-Einstein condensates trapped in a harmonic potential. We investigate the one-dimensional case and get the approximate analytical solutions successfully. Comparisons between the analytical solutions and the numerical solutions have been made. The results indicate that they are in agreement well with each other when the atomic interaction is weakly. We also find a class of exact solutions for the stationary states of the spin-1 system with harmonic potential for a special case.
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
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.
Yasar, Selcuk; Podgornik, Rudolf; Valle-Orero, Jessica; ...
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
Jennings, Robert C; Zucchelli, Giuseppe
2014-01-01
We examine ergodicity and configurational entropy for a dilute pigment solution and for a suspension of plant photosystem particles in which both ground and excited state pigments are present. It is concluded that the pigment solution, due to the extreme brevity of the excited state lifetime, is non-ergodic and the configurational entropy approaches zero. Conversely, due to the rapid energy transfer among pigments, each photosystem is ergodic and the configurational entropy is positive. This decreases the free energy of the single photosystem pigment array by a small amount. On the other hand, the suspension of photosystems is non-ergodic and the configurational entropy approaches zero. The overall configurational entropy which, in principle, includes contributions from both the single excited photosystems and the suspension which contains excited photosystems, also approaches zero. Thus the configurational entropy upon photon absorption by either a pigment solution or a suspension of photosystem particles is approximately zero.
Raghunathan, Ramya; Kumarasamy, Elango; Iyer, Akila; Ugrinov, Angel; Sivaguru, J
2013-10-07
Atropisomeric α-oxoamides were synthesized and employed for intramolecular Paternò-Büchi reaction leading to very high enantio- and diastereoselectivity in the bicyclic oxetane photoproduct. A reversal of product selectivity was observed in solution and in the solid-state.
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 ...
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,...
Cui, Lei; Peng, Zhixing; Ji, Chunfei; Huang, Junhai; Huang, Dongting; Ma, Jie; Zhang, Shuping; Qian, Xuhong; Xu, Yufang
2014-02-11
A new probe based on the Gabriel mechanism was designed and first used for hydrazine detection with high selectivity against other amines in aqueous solution. Importantly, the probe could be used for gas-state discrimination of hydrazine with different concentrations. Additionally, probe could also be applied for the imaging of hydrazine in living cells.
Ground state solution for a class of Schrödinger equations involving general critical growth term
NASA Astrophysics Data System (ADS)
Liu, Jiu; Liao, Jia-Feng; Tang, Chun-Lei
2017-03-01
In this paper, we study a class of Schrödinger equations -△u=k(u),x∈RN, where N≥slant 3 and k satisfies very general critical growth conditions. By using the Pohozaev constraint, we obtain a positive ground state solution which is radially symmetric.
NASA Astrophysics Data System (ADS)
Osherov, V. I.; Ushakov, V. G.
2006-02-01
The exact quantum-mechanical solution of the two-state exponential model with one flat diabatic potential has been found for a specific energy below the higher threshold. The N matrix has been derived in the adiabatic representation and the closed analytical expression for the transmission coefficient has been obtained. The results reveal the influence of the closed channel on the nonadiabatic transmission.
Osherov, V. I.; Ushakov, V. G.
2006-02-15
The exact quantum-mechanical solution of the two-state exponential model with one flat diabatic potential has been found for a specific energy below the higher threshold. The N matrix has been derived in the adiabatic representation and the closed analytical expression for the transmission coefficient has been obtained. The results reveal the influence of the closed channel on the nonadiabatic transmission.
NASA Astrophysics Data System (ADS)
Coscia, Vincenzo
2016-11-01
We prove that in a bounded Lipschitz domain of R^3 the steady-state Navier-Stokes equations with boundary data in L^2(partial Ω ) have a very weak solution \\varvec{u}in L^3(Ω ) , unique for large viscosity.
Alfonso, María; Fernández, Israel; Tárraga, Alberto; Molina, Pedro
2015-05-15
Fluorescent solid 5-pyridylimidazobenzothiadiazole displays a remarkable solvatofluorochromism and with Zn(AcO)2 and Cd(AcO)2, either in solution or under solvent-free conditions, forms ion-pair complexes that in the solid state can be discriminated and separated by fluorescence measurements and selective extraction with diethyl ether or chloroform.
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
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.
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.
Rai, R.N.; Kant, Shiva; Reddi, R.S.B.; Ganesamoorthy, S.; Gupta, P.K.
2016-01-15
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. - Highlights: • The hygroscopic character of urea was modified by making the solid solution • Solid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.
Parmar, Nitin; Amin, Saima; Singla, Neelam; Kohli, Kanchan
2012-01-01
The objectives of this research were to evaluate the stability of lercanidipine in solution state and solid state and explore the compatibility of drug with oils, surfactants and cosurfactants as excipients. The effect of pH on the degradation in solution state was studied through pH-rate profile of lercanidipine in constant ionic strength buffer solutions in pH range 1-8 which gives the pH of maximum stability. Powdered lercanidipine was stored under 40°C/0%~75% relative humidities (RH) or 0% RH/5~50°C to study the influence of RH and temperature on the stability of lercanidipine in solid state. Binary mixtures of lercanidipine and different excipients were stored at 40°C/75% RH, 40°C and at room temperature for excipient compatibility evaluation. The degradation of lercanidipine at different pH appears to fit a typical first-order reaction, but in solid state, it does not fit any obvious reaction model. Moisture content and temperature both play important roles affecting the degradation rate. Lercanidipine exhibits good compatibility with surfactants, cosurfactants and oils as excipients under stressed conditions of different storage temperature in a 3-week screening study. Moreover, the proposed high-performance liquid chromatography method was utilized to investigate the kinetics of the acidic and alkaline degradation processes of lercanidipine at different temperatures.
McBranch, D.; Klimov, V.; Smilowitz, L.; Wang, H.; Wudl, F.
1996-11-01
We compare detailed dynamics of the excited-state absorption for C{sub 60} in solution, thin films, and entrapped in an inorganic sol-gel glass matrix. Our results demonstrate that the microscopic morphology of the C{sub 60} molecule plays a crucial role in determining the relaxation dynamics. This is a key factor for applications in optical limiting for nanosecond pulses using reverse saturable absorption. We find that the dynamics of the C{sub 60}-glass composite occur on long (ns) timescales, comparable to that in solution; thin film samples, by contrast, show rapid decay (<20 picoseconds). These results demonstrate that the C{sub 60}-sol-gel glass composites contain C{sub 60} in a molecular dispersion, and are suitable candidates for solid-state optical limiting. Multispectral analysis of the decay dynamics in solution allows accurate determination of both the intersystem crossing time (600 {+-}100 ps) and the relative strengths of the singlet and triplet excited-state cross sections as a function of wavelength from 450-950 nm. The triplet excited-state cross section is greater than that for the singlet excited-state over the range from 620-810 nm.
Trokiner, Arlette; Bessière, Aurélie; Thouvenot, René; Hau, Damien; Marko, Jean; Nardello, Véronique; Pierlot, Christel; Aubry, Jean-Marie
2004-06-01
In order to get some insight into the mechanism of the disproportionation of hydrogen peroxide catalyzed by calcium hydroxide, 43Ca NMR spectra of enriched samples of calcium peroxides and of their precursors have been studied in both solution and solid state. This study demonstrates that no well-defined peroxidized calcium species are formed in solution, showing that the catalytic role of calcium is likely restricted to the solid state. Most of the calcium compounds that could be involved in the catalytic process have been investigated with solid state NMR. The shift and quadrupolar parameters of Ca(OH)2, CaO2.8H2O and CaO2.2H2O2 are reported for the first time. These parameters are different enough to allow the quantitative analysis of a complex mixture of these compounds by NMR.
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 ...
Núñez, Cristina; Bastida, Rufina; Macías, Alejandro; Mato-Iglesias, Marta; Platas-Iglesias, Carlos; Valencia, Laura
2008-08-07
Lanthanide complexes of a hexaaza macrocyclic ligand containing acetohydrazide pendants (L) have been synthesised (Ln = La-Er, except Pm), and structural studies have been carried out both in the solid state and in aqueous solution. Attempts to isolate the complexes of the heaviest Ln(iii) ions (Ln = Tm-Lu) were unsuccessful. The crystal structures of the ligand and its lanthanum complex have been determined by single-crystal X-ray crystallography. The X-ray crystal structure of [La(L)](3+) shows the metal ion being ten-coordinate, with the acetohydrazide pendants situated alternatively above and below the plane of the macrocycle. The two five membered chelate rings formed by the ethylenediamine moieties adopt (deltadelta) [or (lambdalambda)] conformations. The [Ln(L)](3+) complexes have been characterised by means of density-functional theory (DFT) calculations (B3LYP model). The structures obtained from these theoretical calculations are in very good agreement with the experimental solution structures, as obtained from paramagnetic NMR measurements on the Ce(iii), Pr(III), Nd(III) and Eu(III) complexes. The complexes adopt in aqueous solution a D(2) structure with the ligand adopting a (deltadelta) [or (lambdalambda)] conformation.
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.
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.
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
NASA Astrophysics Data System (ADS)
Campbell, Russell; Oppo, Gian-Luca
2016-10-01
A model of a Bose-Einstein condensate in a ring optical lattice with atomic dissipations applied at a stationary or at a moving location on the ring is presented. The localized dissipation is shown to generate and stabilize both stationary and traveling lattice solitons. Among many localized solutions, we have generated spatially stationary quasiperiodic lattice solitons and a family of traveling lattice solitons with two intensity peaks per potential well with no counterpart in the discrete case. Collisions between traveling and stationary lattice solitons as well as between two traveling lattice solitons display a critical dependence from the lattice depth. Stable counterpropagating solitons in ring lattices can find applications in gyroscope interferometers with ultracold gases.
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.
Sun, Jitao; Lin, Hai
2008-09-01
This paper investigates the stationary oscillation for an impulsive delayed system which represents a class of nonlinear hybrid systems. First, a new concept of S-stability is introduced for nonlinear impulsive delayed systems. Based on this new concept and fixed point theorem, the relationship between S-stability and stationary oscillation (i.e., existence, uniqueness and global stability of periodic solutions) for the nonlinear impulsive delayed system is explored. It is shown that the nonlinear impulsive delayed system has a stationary oscillation if the system is S-stable. Second, an easily verifiable sufficient condition is then obtained for stationary oscillations of nonautonomous neural networks with both time delays and impulses by using the new criterion. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed method.
The state-specific expansion approach to the solution of the time-dependent many-electron problem
NASA Astrophysics Data System (ADS)
Nicolaides, Cleanthes A.
2016-12-01
The ab initio, non-perturbative solution of the many-electron time-dependent Schrödinger equation for the time-resolved description of electron excitations, correlations and rearrangements in atoms and molecules on femtosecond and attosecond scales, may be characterized as a new frontier of many-electron physics and of quantum chemistry. I outline elements of the theory and applications of the state-specific expansion approach to the solution of such time-dependent many-electron problems involving arbitrary electronic structures.
Yang, Hui; Ren, Qun; Zhang, Zhaojie
2006-12-01
When starved of essential nutrients, yeast cells cease mitotic division and enter an alternative state called the 'stationary phase'. In this paper, we report that stationary cells enter two major pathways: meiosis and apoptosis. Using transmission electron microscopy, five types of cell were identified in the stationary phase: (1) cells with chromosome condensed nuclei; (2) cells with normal, homogeneously stained nuclei; (3) sporulated cells; (4) apoptotic cells, in which chromatin, but not individual chromosomes, was condensed; and (5) dead cells, in which nuclei and cytoplasm were degraded. Further evidence using live cell imaging and mutation analysis suggested that cells with condensed chromosomes underwent meiosis, whereas chromatin condensed cells underwent apoptotic cell death. Cells with homogeneous nuclei are believed to be in the true resting state and undergo cell death when starvation continues. Chromosome or chromatin condensation may serve as a hallmark of life or death for stationary cells.
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.
NASA Astrophysics Data System (ADS)
Malinina, M. S.; Ivanilova, S. V.
2008-04-01
The interannual, seasonal, and daily dynamics of the contents of phenol compounds in the soil solution of a peat-podzolic-gleyic soil in the southern taiga are considered. The concentrations of phenol compounds in the studied soil remain relatively stable. In the solutions obtained from different soil types, the main limiting factor is the degree of hydromorphism, which manifests itself via the biological factor—the intensity of the microorganisms activity and the composition and quality of the forest litters.
1995-03-01
caloric ( Aspartame ) placebo. A third group drank water. Fluid intake for all groups was ad libitum; food intake was restricted to -2600 kcal-dayŕ...intake of a colored, non-caloric sweetened ( Aspartame ) solution which contained no electrolytes (Placebo). The CHO-E beverage and the placebo solution...contributing factors. The suppressed proliferative response of the Aspartame sweetened placebo group relative to the other two groups is of
Linear prediction of stationary vector sequences
NASA Technical Reports Server (NTRS)
Baram, Yoram
1988-01-01
The class of all linear predictors of minimal order for a stationary vector-valued process is specified in terms of linear transformations on the associated Hankel covariance matrix. Two particular transformations, yielding computationally efficient construction schemes, are proposed.
Chaotic orbit effects in a stationary single particle probabilistic density
NASA Astrophysics Data System (ADS)
Ogawa, Shun; Leoncini, Xavier; Vittot, Michel; Dif-Pradalier, Guilhem; Garbet, Xavier
2016-10-01
Chaotic particle orbit effects in a stationary density function or macroscopic quantities are investigated. A considered field consists with static magnetic field and null electric field in a cylinder, then a test particle is driven by the Lorentz force. We firstly consider an axisymmetric magnetic field, where three integrals of motion coexist. So that the test particle motion is completely integrable, and its Hamiltonian is reduced to an effective one degree of freedom Hamiltonian. For some initial states, the effective potential of this reduced Hamiltonian has a saddle point and a separatrix bringing about some chaos when a perturbation is added to the magnetic field. We investigate how this chaos modifies the stationary density function. We acknowledge support of the A *MIDEX project (n ∘ ANR-11- IDEX-0001-02) funded by the ``investissements d'Avenir'' French Government program, managed by the French National Research Agency (ANR).
Dynamical observations of self-stabilizing stationary light
NASA Astrophysics Data System (ADS)
Everett, J. L.; Campbell, G. T.; Cho, Y.-W.; Vernaz-Gris, P.; Higginbottom, D. B.; Pinel, O.; Robins, N. P.; Lam, P. K.; Buchler, B. C.
2017-01-01
The precise control of atom-light interactions is vital to many quantum technologies. For instance, atomic systems can be used to slow and store light, acting as a quantum memory. Optical storage can be achieved via stopped light, where no optical energy continues to exist in the atomic system, or as stationary light, where some optical energy remains present during storage. Here, we demonstrate a form of self-stabilizing stationary light. From any initial state, our atom-light system evolves to a stable configuration that may contain bright optical excitations trapped within the atomic ensemble. This phenomenon is verified experimentally in a cloud of cold Rb87 atoms. The spinwave in our atomic cloud is imaged from the side, allowing direct comparison with theoretical predictions.
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.
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
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.
Gravitational and mass distribution effects on stationary superwinds
NASA Astrophysics Data System (ADS)
Añorve-Zeferino, G. A.
2016-11-01
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 us 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.
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)
Lamy, P.; Jorda, L.; Kaasalainen, M.; Hviid, S.; Faury, G.; Toth, I.; Groussin, O.
2014-07-01
In preparation of ESA's ROSETTA mission to comet 67P/Churyumov-Gerasimenko, solutions for the shape and rotational state of its nucleus have been published based on observation with the Hubble and Spitzer space telescopes as well as ground-based observations (Lamy et al. 2006, 2007, 2008; Lowry et al. 2012). Following the wake-up of the Rosetta spacecraft in January 2014 and the successful commissioning of the OSIRIS camera system in March, a first lightcurve of the inactive nucleus has been obtained on 23 March 2014 with the OSIRIS Narrow Angle Camera (NAC). Further lightcurves will be acquired in the forthcoming months. We will present an updated solution for the shape and rotational state based on these data sets as of end of June 2014 combined with past Hubble and Spitzer space telescopes as well as ground-based observations using the technique of lightcurve inversion.
Gor, G Yu; Kuchma, A E
2009-12-21
The paper presents an analytical description of the growth of a two-component bubble in a binary liquid-gas solution. We obtain asymptotic self-similar time dependence of the bubble radius and analytical expressions for the nonsteady profiles of dissolved gases around the bubble. We show that the necessary condition for the self-similar regime of bubble growth is the constant, steady-state composition of the bubble. The equation for the steady-state composition is obtained. We reveal the dependence of the steady-state composition on the solubility laws of the bubble components. Besides, the universal, independent from the solubility laws, expressions for the steady-state composition are obtained for the case of strong supersaturations, which are typical for the homogeneous nucleation of a bubble.
Lü, Xiaoling; Jiang, Liwei; Zheng, Yisong
2014-01-22
Analytic solutions of the quasi-one-dimensional (q1D) electron states around an extended line defect in a graphene lattice are derived within the tight-binding model. Then, the electronic properties of this kind of boundary state in graphene are studied in detail. It is found that one subband composed of the even-parity boundary states emerges in the vicinity of the Dirac point. In particular, when the bulk band is gapped, such a one-dimensional subband remains in the bandgap, spanning two inequivalent valleys. In addition, this boundary state subband exhibits nontrivial dispersion, which can carry the valley polarized charge current flowing along the extended line defect. As a result, the line defect behaves like a one-dimensional channel for electronic transport. Moreover, its appearance in graphene or a hexagonal boron nitride sheet provides a promising way to print electric circuits in these two-dimensional materials.
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.
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.
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.
Collagen functionalized with unsaturated cyclic anhydrides-interactions in solution and solid state.
Potorac, S; Popa, M; Picton, L; Dulong, V; Verestiuc, L; Le Cerf, D
2014-03-01
Maleic anhydride (CMA) and itaconic anhydride modified collagen (CITA) were prepared as precursors for production of interpenetrated polymer networks (IPN). Calculated values for Huggins coefficient in aqueous diluted and semi-diluted solutions of modified collagen indicated a slightly tendency of aggregation for itaconic anhydride-modified collagen. In semi-diluted solution collagen (Coll) and CMA present slightly differences in the thixotropic behavior, while CITA has a pronounced thixotropic behavior. Flow and oscillatory measurements revealed an elastic behavior of the collagen solutions, pure and modified with MA or ITA, as the storage modulus (G') has always a superior value compared with the loss modulus (G″). The denaturation temperature (Td) of unmodified collagen increased from 34°C to 40°C for CMA and to 39°C for CITA respectively, by formation of covalent bonds that stabilize the triple helix.
Approximate solutions for half-dark solitons in spinor non-equilibrium Polariton condensates
Pinsker, Florian
2015-11-15
In this work I generalize and apply an analytical approximation to analyze 1D states of non-equilibrium spinor polariton Bose–Einstein condensates (BEC). Solutions for the condensate wave functions carrying black solitons and half-dark solitons are presented. The derivation is based on the non-conservative Lagrangian formalism for complex Ginzburg–Landau type equations (cGLE), which provides ordinary differential equations for the parameters of the dark soliton solutions in their dynamic environment. Explicit expressions for the stationary dark soliton solution are stated. Subsequently the method is extended to spin sensitive polariton condensates, which yields ordinary differential equations for the parameters of half-dark solitons. Finally a stationary case with explicit expressions for half-dark solitons is presented.
Xie, Bin-Bin; Wang, Qian; Guo, Wei-Wei; Cui, Ganglong
2017-03-15
The photophysics of thiothymines has been extensively studied computationally in the past few years due to their significant potential as photosensitizers in photodynamic therapy. However, the corresponding computational studies of the photophysical mechanism of 2,4-dithiothymine are scarce. Herein we have employed the CASPT2//CASSCF and QM(CASPT2//CASSCF)/MM methods to systematically explore the excited-state decay mechanism of 2,4-dithiothymine in isolated, microsolvated, and aqueous surroundings. First, we have optimized minima and conical intersections in and between the lowest six excited singlet and triplet states i.e., , , , , and ; then, based on computed excited-state decay paths and spin-orbit couplings, we have proposed several nonadiabatic pathways that efficiently populate the lowest triplet state to explain the experimentally observed ultrahigh triplet-state quantum yield. Moreover, we have found that the excited-state decay mechanism in microsolvated and aqueous environments is more complicated than that in the gas phase. The solute-solvent interaction has significant effects on the excited-state potential energy surfaces of 2,4-dithiothymine and eventually on its excited-state decay mechanism. Finally, the present computational efforts contribute important mechanistic knowledge to the understanding of the photophysics of thiothymine-based photosensitizers.
Dodd, R. J.
1996-01-01
I present simple analytical methods for computing the properties of ground and excited states of Bose-Einstein condensates, and compare their results to extensive numerical simulations. I consider the effect of vortices in the condensate for both positive and negative scattering lengths, a, and find an analytical expression for the large-N0 limit of the vortex critical frequency for a > 0, by approximate solution of the time-independent nonlinear Schrödinger equation. PMID:27805107
Dodd, R J
1996-01-01
I present simple analytical methods for computing the properties of ground and excited states of Bose-Einstein condensates, and compare their results to extensive numerical simulations. I consider the effect of vortices in the condensate for both positive and negative scattering lengths, a, and find an analytical expression for the large-N0 limit of the vortex critical frequency for a > 0, by approximate solution of the time-independent nonlinear Schrödinger equation.
NASA Astrophysics Data System (ADS)
Stets, E.
2014-12-01
Trends in alkalinity and other solutes are evident in large rivers of the United States (U.S.) due to a variety of factors. Nutrient inputs, agricultural lime, decreasing acidic inputs, and changing flow conditions all contribute to trends in major solutes. In small, minimally disturbed headwater watersheds with limited acid neutralizing capacity, solute trends resulting from changes in acidic deposition are well documented. Larger rivers tend to have greater acid neutralizing capacity and are subject to a greater number of anthropogenic pressures. Therefore, the effects of acid deposition on larger rivers is expected to be minimal. In this study, trends in alkalinity and other solutes were determined in large rivers spanning a range of climate and land use characteristics in the U.S. Multi-decadal trend analyses were performed (1945-2010) using a robust flow-weighting scheme. Alkalinity increased in most rivers although the factors leading to the increases were highly diverse. In several rivers in the Northeastern U.S., the timing and magnitude of alkalinity trends indicated that changes in atmospheric deposition played a role in solute trends. Despite the recent increases in alkalinity, modern alkalinity concentrations in U.S. rivers are remarkably similar to those observed in the early 20th century (1906-1910). On the other hand, sulfate and calcium concentrations remain elevated with respect to data from the early 20th century suggesting that acidification processes are ongoing, although improvements occurred in many areas in recent decades.
NASA Astrophysics Data System (ADS)
Elman, Howard C.; Forstall, Virginia
2017-04-01
Reduced-order modeling is an efficient approach for solving parameterized discrete partial differential equations when the solution is needed at many parameter values. An offline step approximates the solution space and an online step utilizes this approximation, the reduced basis, to solve a smaller reduced problem at significantly lower cost, producing an accurate estimate of the solution. For nonlinear problems, however, standard methods do not achieve the desired cost savings. Empirical interpolation methods represent a modification of this methodology used for cases of nonlinear operators or nonaffine parameter dependence. These methods identify points in the discretization necessary for representing the nonlinear component of the reduced model accurately, and they incur online computational costs that are independent of the spatial dimension $N$. We will show that empirical interpolation methods can be used to significantly reduce the costs of solving parameterized versions of the Navier-Stokes equations, and that iterative solution methods can be used in place of direct methods to further reduce the costs of solving the algebraic systems arising from reduced-order models.
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 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…
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 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…
NASA Astrophysics Data System (ADS)
Leo, Mario; Leo, Rosario Antonio; Tempesta, Piergiulio
2013-06-01
In a recent paper [M. Leo, R.A. Leo, P. Tempesta, C. Tsallis, Phys. Rev. E 85 (2012) 031149], the existence of quasi-stationary states for the Fermi-Pasta-Ulam β system has been shown numerically, by analyzing the stability properties of the N/4-mode exact nonlinear solution. Here we study the energy distribution of the modes N/4, N/3 and N/2, when they are unstable, as a function of N and of the initial excitation energy. We observe that the classical Boltzmann weight is replaced by a different weight, expressed by a q-exponential function.
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
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.
Scattering state solutions of the Duffin-Kemmer-Petiau equation with the Varshni potential model
NASA Astrophysics Data System (ADS)
Oluwadare, O. J.; Oyewumi, K. J.
2017-02-01
The scattering state of the Duffin-Kemmer-Petiau equation with the Varshni potential was studied. The asymptotic wave function, the scattering phase shift and normalization constant were obtained for any J states by dealing with the centrifugal term using a suitable approximation. The analytical properties of the scattering amplitude and the bound state energy were obtained and discussed. Our numerical and graphical results indicate that the scattering phase shift depends largely on total angular momentum J , screening parameter β and potential strengths a and b.
Excited-state dynamics of rhodamine 6G in aqueous solution and at the dodecane/water interface.
Fedoseeva, Marina; Letrun, Romain; Vauthey, Eric
2014-05-15
The excited-state dynamics of rhodamine 6G (R6G) has been investigated in aqueous solution using ultrafast transient absorption spectroscopy and at the dodecane/water interface using the femtosecond time-resolved surface second harmonic generation (SSHG) technique. As the R6G concentration exceeds ca. 1 mM in bulk water, both R6G monomers and aggregates are excited to a different extent when using pump pulses at 500 and 530 nm. The excited-state lifetime of the monomers is shortened compared to dilute solutions because of the occurrence of excitation energy transfer to the aggregates, which themselves decay nonradiatively to the ground state with a ca. 70 ps time constant. At the dodecane/water interface, both monomers and aggregates contribute to the SSHG signal to an extent that depends on the bulk concentration, the pump and probe wavelengths, and the polarization of probe and signal beams. The excited-state lifetime of the monomers at the interface is of the order of a few picoseconds even at bulk concentrations where it is as large as several nanoseconds. This is explained by the relatively high interfacial affinity of R6G that leads to a large interfacial concentration, favoring aggregation and thus rapid excitation energy transfer from monomers to aggregates.
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.
Personal pollen exposure compared to stationary measurements.
Riediker, M; Keller, S; Wüthrich, B; Koller, T; Monn, C
2000-01-01
The aim of this study was to examine to what extent stationary outdoor pollen measurements are representative for estimating personal exposure to pollen. Ten subjects were studied during a total of 36 days in spring and summer Pollen was sampled using personal SKC total dust samplers and stationary Burkard pollen traps. The personal activity pattern was recorded quarter-hourly as well as the time spent outdoors. As a reference, SKC and Burkard samplers were run stationary and in parallel. Stationary comparison of the samplers showed good correlation (r = 0.981, p <0.001). However, the SKC sampler collected systematically about four times less pollen than the Burkard sampler. Taking into account the systematic difference between the sampling devices, the personal exposure data were about 30% of the stationary pollen concentrations with significant correlation (log-transformed data, r = 0.719, p <0.0001). Considering the average time the subjects spent outdoors (14% of sampling time), the indoor-outdoor ratio for pollen was 0.2. In conclusion, pollen reports are reliable for estimating personal exposure over a limited time period although personal pollen exposure is much lower.
Development of an Efficient Solution Scheme for Incompressible Steady- State Flow
1989-04-01
Investigation," Technical Report REMR-HY-4, US Army Engineer Waterways Experiment Station, Vicksburg, MS. Bernard, R. S., and Thompson , J . F . 1984. "Mass...0208, AIAA 24th Aerospace Sciences Meeting, Reno, NV. Mastin, C. W., and Thompson , J . F . 1978. "Three-Dimensional Body-Fitted Coordinate Systems for... Thompson , J . F . 1984. "A Vectorized Solution for Incompressible Flow," AIAA Paper 84-1534, AIAA 17th Fluid Dynamics, Plasma Dynamics, and Lasers Conference
NASA Astrophysics Data System (ADS)
Bomont, Jean-Marc; Pastore, Giorgio
2015-09-01
We propose and discuss a straightforward search protocol for the glass-like solutions of the integral equations of the two-replica approach to the random first-order transition theory of the liquid-glass transition. The new numerical strategy supplements those recently introduced by Jean-Pierre Hansen and ourselves. A few results for inverse power (1/r12) fluid are discussed and critically compared with results from other approaches.
Arfin, Najmul; Bohidar, H B
2012-04-01
Solution behaviour of hydroxyethyl cellulose (HEC) is reported in the polymer concentration range spanning over two decades (c=0.002-5% (w/v)). The results conclude the following: (i) dilute solution regime prevailed for c<0.2% (w/v), flexible HEC fibres of typical length ≈ 1 μm and persistence length ≈ 10 nm were found here, (ii) for 0.2
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.
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.
Coordination chemistry study of hydrated and solvated lead(II) ions in solution and solid state.
Persson, Ingmar; Lyczko, Krzysztof; Lundberg, Daniel; Eriksson, Lars; Płaczek, Anna
2011-02-07
The coordination chemistry of lead(II) in the oxygen donor solvents water, dimethylsulfoxide (dmso, Me(2)SO), N,N-dimethylformamide (dmf), N,N-dimethylacetamide (dma), N,N'-dimethylpropyleneurea (dmpu), and 1,1,3,3-tetramethylurea (tmu), as well as in the sulfur donor solvent N,N-dimethylthioformamide (dmtf), has been investigated by extended X-ray absorption fine structure (EXAFS) and/or large angle X-ray scattering (LAXS) in solution, and by single crystal X-ray diffraction and/or EXAFS of solid hydrates and solvates. Lead(II) may either form hemidirected complexes with large bond distance distribution and an apparent gap for excess electron density, or holodirected ones with a symmetric coordination sphere with normal bond distance distribution, depending on the strength of antibonding lead 6s/ligand np molecular orbital interactions and ligand-ligand interactions. The crystallographic data show that the solid lead(II) perchlorate and trifluoromethanesulfonate hydrate structures are hemidirected, while the solid lead(II) solvates of dma and dmpu have regular octahedral configuration with holodirected geometry and mean Pb-O bond distances in the range 2.50-2.52 Å. EXAFS data on the hydrated lead(II) ion in aqueous solution show broad bond distance distribution and a lack of inner-core multiple scattering contributions strongly indicating a hemidirected structure. The Pb-O bond distances found both by EXAFS and LAXS, 2.54(1) Å, point to a six-coordinate hydrated lead(II) ion in hemidirected fashion with an unevenly distributed electron density. The results obtained for the dmso solvated lead(II) ion in solution are ambiguous, but for the most part support a six-coordinate hemidirected complex. The mean Pb-O bond distances determined in dmf and dma solution by LAXS, 2.55(1) and 2.48(1) Å, respectively, indicate that in both solvate complexes lead(II) binds six solvent molecules with the former complex being hemidirected whereas the latter is holodirected. The
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.
Borges, Endler M; Collins, Carol H
2012-03-02
The effects of mobile phase pH, temperature, buffer type and buffer concentration on the selectivity and stability of four stationary phases, with different PMOS loadings, prepared by the thermal immobilization of poly(methyloctylsiloxane) on to silica (PMOS-SiO₂), were evaluated with both hydrophobic and hydrophilic basic solutes. These solutes show longer retention times at near neutral pH, where both the silanols and the basic solutes are partially ionized, and shorter retention times in more alkaline pH, where the silanols are mostly ionized and the basic solutes are not ionized. Increases in temperature and buffer concentration also result in shorter retention times. These PMOS-SiO₂ stationary phases are quite stable at low pH and are also stable at ambient temperature (23 °C) using pH 7 phosphate. The PMOS-SiO₂ stationary phases are more stable at higher pH using triethylamine (pH 11) and borate (pH 10) buffers than with phosphate and carbonate buffers. Temperature increases stationary phase degradation, while buffer concentration has a minimal effect on stationary phase degradation, indicating that these PMOS-SiO₂ stationary phases have stabilities similar to the equivalent chemically bonded phases.
Lemeshko, Mikhail; Mustafa, Mustafa; Kais, Sabre; Friedrich, Bretislav
2011-04-15
By invoking supersymmetry, we found a condition under which the Stark-effect problem for a polar and polarizable molecule subject to nonresonant electric fields becomes exactly solvable for the |J-tilde=m,m> family of stretched states. The analytic expressions for the wave function and eigenenergy and other expectation values allow one to readily reverse-engineer the problem of finding the values of the interaction parameters required for creating quantum states with preordained characteristics. The method also allows the construction of families of isospectral potentials, realizable with combined fields.
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.
Xiao, Yu-Hao; Xi, Gang; Zhao, Xuan-Xuan; Zhou, Shuai; Zhou, Ze-Quan; Zhao, Bao-Xiang
2015-07-01
A novel coumarin-based fluorescent probe CF was synthesized for the detection of hydrazine both in aqueous solution and vapor state with high sensitivity and selectivity. Upon addition of hydrazine, the solution of probe CF in MeCN-H2O (3/7, v/v, buffered CH3COOH/CH3COONa) at pH 5.0 exhibited a remarkable change in emission color from pale green to light blue, which could be recognized with naked eyes. Applied in weak acid condition, probe CF could detect hydrazine selectively with large amount of unknown environments according to the competing tests. Besides, with the limit of detection 8.32 ppb (2.6 × 10(-7) M), probe CF could well meet the request (10 ppb) of the U.S. Environmental Protection Agency (EPA).
The problem of characterising stationary data for the vacuum Einstein equations
NASA Astrophysics Data System (ADS)
Tod, Paul
2017-02-01
We take a step towards characterising stationary data for the vacuum Einstein equations, by finding a necessary condition on initial data for which the evolution is a solution of the vacuum equations admitting a Killing vector, which is time-like at least in some region of the Cauchy development.
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.
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.
The principle of stationary variance in quantum field theory
NASA Astrophysics Data System (ADS)
Siringo, Fabio
2014-02-01
The principle of stationary variance is advocated as a viable variational approach to quantum field theory (QFT). The method is based on the principle that the variance of energy should be at its minimum when the state of a quantum system reaches its best approximation for an eigenstate. While not too much popular in quantum mechanics (QM), the method is shown to be valuable in QFT and three special examples are given in very different areas ranging from Heisenberg model of antiferromagnetism (AF) to quantum electrodynamics (QED) and gauge theories.
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…
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…
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...
Changing Cycle Lengths in State-Transition Models: Challenges and Solutions.
Chhatwal, Jagpreet; Jayasuriya, Suren; Elbasha, Elamin H
2016-11-01
The choice of a cycle length in state-transition models should be determined by the frequency of clinical events and interventions. Sometimes there is need to decrease the cycle length of an existing state-transition model to reduce error in outcomes resulting from discretization of the underlying continuous-time phenomena or to increase the cycle length to gain computational efficiency. Cycle length conversion is also frequently required if a new state-transition model is built using observational data that have a different measurement interval than the model's cycle length. We show that a commonly used method of converting transition probabilities to different cycle lengths is incorrect and can provide imprecise estimates of model outcomes. We present an accurate approach that is based on finding the root of a transition probability matrix using eigendecomposition. We present underlying mathematical challenges of converting cycle length in state-transition models and provide numerical approximation methods when the eigendecomposition method fails. Several examples and analytical proofs show that our approach is more general and leads to more accurate estimates of model outcomes than the commonly used approach. MATLAB codes and a user-friendly online toolkit are made available for the implementation of the proposed methods.
Technology Transfer Automated Retrieval System (TEKTRAN)
In the northeastern U.S., organic dairy production has increased rapidly in recent years, as Maine, Vermont, Pennsylvania and New York all rank in the top six U.S. states for the number of cows on organic dairy farms. Organic dairy farms have significant differences from conventional counterparts, i...
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...
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…
Synchronization and Bellerophon states in conformist and contrarian oscillators
Qiu, Tian; Boccaletti, Stefano; Bonamassa, Ivan; Zou, Yong; Zhou, Jie; Liu, Zonghua; Guan, Shuguang
2016-01-01
The study of synchronization in generalized Kuramoto models has witnessed an intense boost in the last decade. Several collective states were discovered, such as partially synchronized, chimera, π or traveling wave states. We here consider two populations of globally coupled conformist and contrarian oscillators (with different, randomly distributed frequencies), and explore the effects of a frequency–dependent distribution of the couplings on the collective behaviour of the system. By means of linear stability analysis and mean–field theory, a series of exact solutions is extracted describing the critical points for synchronization, as well as all the emerging stationary coherent states. In particular, a novel non-stationary state, here named as Bellerophon state, is identified which is essentially different from all other coherent states previously reported in the Literature. A robust verification of the rigorous predictions is supported by extensive numerical simulations. PMID:27827411
Synchronization and Bellerophon states in conformist and contrarian oscillators
NASA Astrophysics Data System (ADS)
Qiu, Tian; Boccaletti, Stefano; Bonamassa, Ivan; Zou, Yong; Zhou, Jie; Liu, Zonghua; Guan, Shuguang
2016-11-01
The study of synchronization in generalized Kuramoto models has witnessed an intense boost in the last decade. Several collective states were discovered, such as partially synchronized, chimera, π or traveling wave states. We here consider two populations of globally coupled conformist and contrarian oscillators (with different, randomly distributed frequencies), and explore the effects of a frequency–dependent distribution of the couplings on the collective behaviour of the system. By means of linear stability analysis and mean–field theory, a series of exact solutions is extracted describing the critical points for synchronization, as well as all the emerging stationary coherent states. In particular, a novel non-stationary state, here named as Bellerophon state, is identified which is essentially different from all other coherent states previously reported in the Literature. A robust verification of the rigorous predictions is supported by extensive numerical simulations.
Zaleski, Curtis M; Tricard, Simon; Depperman, Ezra C; Wernsdorfer, Wolfgang; Mallah, Talal; Kirk, Martin L; Pecoraro, Vincent L
2011-11-21
The magnetic behavior of the pentanuclear complex of formula Mn(II)(O(2)CCH(3))(2)[12-MC(Mn(III)(N)shi)-4](DMF)(6), 1, was investigated using magnetization and magnetic susceptibility measurements both in the solid state and in solution. Complex 1 has a nearly planar structure, made of a central Mn(II) ion surrounded by four peripheral Mn(III) ions. Solid state variable-field dc magnetic susceptibility experiments demonstrate that 1 possesses a low value for the total spin in the ground state; fitting appropriate expressions to the data results in antiferromangetic coupling both between the peripheral Mn(III) ions (J = -6.3 cm(-1)) and between the central Mn(II) ion and the Mn(III) ones (J' = -4.2 cm(-1)). In order to obtain a reasonable fit, a relatively large single ion magnetic anisotropy (D) value of 1 cm(-1) was necessary for the central Mn(II) ion. The single crystal magnetization measurements using a microsquid array display a very slight opening of the hysteresis loop but only at a very low temperature (0.04 K), which is in line with the ac susceptibility data where a slow relaxation of the magnetization occurs just around 2 K. In frozen solution, complex 1 displays a frequency dependent ac magnetic susceptibility signal with an energy barrier to magnetization reorientation (E) and relaxation time at an infinite temperature (τ(o)) of 14.7 cm(-1) and 1.4 × 10(-7) s, respectively, demonstrating the single molecule magnetic behavior in solution.
NASA Astrophysics Data System (ADS)
Maslova, N. S.; Mantsevich, V. N.; Arseyev, P. I.
2017-02-01
We perform theoretical investigation of the localized state dynamics in the presence of interaction with the reservoir and Coulomb correlations. We analyze kinetic equations for electron occupation numbers with different spins taking into account high order correlation functions for the localized electrons. We reveal that in the stationary state electron occupation numbers with the opposite spins always have the same value - the stationary state is a "paramagnetic" one. "Magnetic" properties can appear only in the non-stationary characteristics of the single-impurity Anderson model and in the dynamics of the localized electrons second order correlation functions. We found, that for deep energy levels and strong Coulomb correlations, relaxation time for initial "magnetic" state can be several orders larger than for "paramagnetic" one. So, long-living "magnetic" moment can exist in the system. We also found non-stationary spin polarized currents flowing in opposite directions for the different spins in the particular time interval.
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.
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.
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)
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.
Calculated equilibria between adjacent valence states of plutonium in simple aqueous solutions
Sweeton, F.H.
1981-02-01
Equilibrium data have been taken from the literature for the oxidation of Pu/sup 3 +/ to Pu/sup 4 +/, Pu/sup 4 +/ to PuO/sub 2//sup +/ and PuO/sub 2//sup +/ to PuO/sub 2//sup 2 +/, and for the hydrolysis of these four plutonium species in dilute solutions. These data have been used to calculate the oxidation-reduction potentials (expressed as E/sub h/) at which the concentrations of the two species (including the hydrolyzed forms) in each pair are equal. These calculations cover the pH range of 0 to 13. The results indicate that there are conditions under which each species can be predominant. The solubility of PuO/sub 2/ under environmental conditions is also discussed.
Photoexcited State Molecular Structures in Solution Studied by Pump-Probe XAFS
NASA Astrophysics Data System (ADS)
Chen, Lin
2002-03-01
The photoexcitation causes displacement of electron densities within or among molecules, which consequently leads to nuclear movements. Such nuclear displacements often occur in transient states with short lifetimes. Knowing transient molecular structures during photochemical reactions is important for understanding fundamental aspects of solar energy conversion and storage. Fast x-ray techniques provide direct probes for these transient structures. Using x-ray pulses from the Advanced Photon Source at Argonne, a laser pulse pump, x-ray pulse probe XAFS technique has been developed to capture transient molecular structures in disordered media with nanosecond time resolution. We have carried out several pump-probe XAFS measurements on 1)identifying a transient molecular structure of the photodissociation product of nickel-tetraphenylporphyrin with piperidine axial ligands (NiTPP-L2); 2)determination of the MLCT state structure of Bis(2,9-dimethyl-1,10-phenanthroline) Copper(I) [Cu(I)(dmp)2]+, and 3) triplet state molecular structures of metalloporphyrins. These studies not only prove the feasibility of the technique, but also gain structural information that otherwise will not be available. Future studies include probing transient structures in electron donor-acceptor complexes and optical polarization selected XAFS (OPS-XAFS) using the same technique with a 100-ps time resolution. This work is supported by the Division of Chemical Sciences, Office of Basic Energy Sciences, U. S. Department of Energy, under contract W-31-109-Eng-38.
Hight, Lauren M; McGuire, Meaghan C; Zhang, Yu; Bork, Matthew A; Fanwick, Phillip E; Wasserman, Adam; McMillin, David R
2013-08-05
Introducing electron-donating groups extends the excited-state lifetimes of platinum(II)-terpyridine complexes in fluid solution. Such systems are of interest for a variety of applications, viz., as DNA-binding agents or as components in luminescence-based devices, especially sensors. The complexes investigated here are of the form [Pt(4'-X-T)Y](+), where 4'-X-T denotes a 4'-substituted 2,2':6',2″-terpyridine ligand and Y denotes the coligand. The π-donating abilities of -X and -Y increase systematically in the orders -NHMe < -NMe2 < -(pyrrolidin-1-yl) and -CN < -Cl < -CCPh, respectively. The results presented include crystal structures of two new 4'-NHMe-T complexes of platinum, as well as absorption, emission, and excited-state lifetime data for nine complexes. Excited-state lifetimes obtained in deoxygenated dichloromethane vary by a factor of 100, ranging from 24 μs for [Pt(4'-pyrr-T)CN](+) to 0.24 μs for [Pt(4'-ma-T)Cl](+), where ma-T denotes 4'-(methylamino)-2,2':6',2″-terpyridine and pyrr-T denotes 4'-(pyrrolidin-1-yl)-2,2':6',2″-terpyridine. Analysis of experimental and computational results shows that introducing a simple amine group on the terpyridine and/or a π-donating coligand engenders the emitting state with intraligand charge-transfer (ILCT) and/or ligand-ligand charge-transfer (LLCT) character. The excited-state lifetime increases when the change in orbital parentage lowers the emission energy, suppresses quenching via d-d states, and encourages delocalization of the excitation onto the ligand(s). At some point, however, the energy is low enough that direct vibronic coupling to the ground-state surface becomes important, and the lifetime begins to decrease again.
Shiraishi, Emi; Maeda, Kazuhiro; Kurata, Hiroyuki
2009-02-01
Numerical simulation of differential equation systems plays a major role in the understanding of how metabolic network models generate particular cellular functions. On the other hand, the classical and technical problems for stiff differential equations still remain to be solved, while many elegant algorithms have been presented. To relax the stiffness problem, we propose new practical methods: the gradual update of differential-algebraic equations based on gradual application of the steady-state approximation to stiff differential equations, and the gradual update of the initial values in differential-algebraic equations. These empirical methods show a high efficiency for simulating the steady-state solutions for the stiff differential equations that existing solvers alone cannot solve. They are effective in extending the applicability of dynamic simulation to biochemical network models.
Calendar Year 2016 Stationary Source Emissions Inventory
Evelo, Stacie
2017-01-01
The City of Albuquerque (COA) Environmental Health Department Air Quality Program has issued stationary source permits and registrations the Department of Energy/Sandia Field Office for operations at the Sandia National Laboratories/New Mexico. This emission inventory report meets the annual reporting compliance requirements for calendar year (CY) 2016 as required by the COA.
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…
Stationary orbits around the Earth and Mars.
NASA Astrophysics Data System (ADS)
Wytrzyszczak, I.
A comparison of stationary orbits around Earth and Mars is drawn. A qualitative image of the individual harmonics of the planet's potential or of some of their groups is presented with its influence on the positions of equilibria. The spectral stability of Martian λ2 and λ4 points is proved.
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.
1989 SYMPOSIUM ON STATIONARY COMBUSTION NOX CONTROL
This paper summarizes information and results presented at the 1989 Symposium on Stationary Combustion NOX Control, held March 6-9, 1989 in San Francisco. Cosponsored by the Electric Power Research Institute (EPRI) and the U.S. Environmental Protection Agency (EPA), the symposiu...
NASA Astrophysics Data System (ADS)
Deuring, Paul; Kračmar, Stanislav; Nečasová, Šárka
We consider a stationary viscous incompressible flow around a translating and rotating body. Optimal rates of decay are derived for the velocity and its gradient, on the basis of a representation formula involving a fundamental solution constructed by R.B. Guenther and E.A. Thomann [The fundamental solution of the linearized Navier-Stokes equations for spinning bodies in three spatial dimensions - time dependent case, J. Math. Fluid Mech. 8 (2006) 77-98], for a linearized system.
NASA Astrophysics Data System (ADS)
Ivanov, M. I.; Kremer, I. A.; Urev, M. V.
2012-03-01
Nedelec vector finite elements are used for the numerical solution of a regularized version of the quasi-stationary Maxwell equations written in terms of a scalar and a vector magnetic potential with special calibration taking into account the conductivity of the medium. An optimal energy estimate for the error of the approximate solution in Lipschitz polyhedral domains is established. Numerical results are presented that demonstrate the stability of the method.
NASA Astrophysics Data System (ADS)
Brodbeck, Othmar; Heusler, Markus
1997-11-01
Using the Kaluza-Klein structure of stationary spacetimes, a framework for analyzing stationary perturbations of static Einstein-Yang-Mills configurations with bosonic matter fields is presented. It is shown that the perturbations giving rise to a nonvanishing ADM angular momentum are governed by a self-adjoint system of equations for a set of gauge-invariant scalar amplitudes. The method is illustrated for SU(2) gauge fields, coupled to a Higgs doublet or a Higgs triplet. It is argued that slowly rotating black holes arise generically in self-gravitating non-Abelian gauge theories with bosonic matter, whereas, in general, soliton solutions do not have rotating counterparts.
Miller, Maria A; Rodrigues, Miguel A; Glass, Matthew A; Singh, Satish K; Johnston, Keith P; Maynard, Jennifer A
2013-04-01
Freezing of protein solutions perturbs protein conformation, potentially leading to aggregate formation during long-term storage in the frozen state. Macroscopic protein concentration profiles in small cylindrical vessels were determined for a monoclonal antibody frozen in a trehalose-based formulation for various freezing protocols. Slow cooling rates led to concentration differences between outer edges of the tank and the center, up to twice the initial concentration. Fast cooling rates resulted in much smaller differences in protein distribution, likely due to the formation of dendritic ice, which traps solutes in micropockets, limiting their transport by convection and diffusion. Analysis of protein stability after more than 6 months storage at either -10°C or -20°C [above glass transition temperature (T'g )] or -80°C (below T'g ) revealed that aggregation correlated with the cooling rate. Slow-cooled vessels stored above T'g exhibited increased aggregation with time. In contrast, fast-cooled vessels and those stored below T'g showed small to no increase in aggregation at any position. Rapid entrapment of protein in a solute matrix by fast freezing results in improved stability even when stored above T'g . © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1194-1208, 2013.
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
SU(1,1) solution for the Dunkl oscillator in two dimensions and its coherent states
NASA Astrophysics Data System (ADS)
Salazar-Ramırez, M.; Ojeda-Guillén, D.; Mota, R. D.; Granados, V. D.
2017-01-01
We study the Dunkl oscillator in two dimensions by the su(1,1) algebraic method. We apply the Schrödinger factorization to the radial Hamiltonian of the Dunkl oscillator to find the su(1,1) Lie algebra generators. The energy spectrum is found by using the theory of unitary irreducible representations. By solving analytically the Schrödinger equation, we construct the Sturmian basis for the unitary irreducible representations of the su(1,1) Lie algebra. We construct the SU(1,1) Perelomov radial coherent states for this problem and compute their time evolution.
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.
Rare switching events in non-stationary systems.
Becker, Nils B; ten Wolde, Pieter Rein
2012-05-07
Physical systems with many degrees of freedom can often be understood in terms of transitions between a small number of metastable states. For time-homogeneous systems with short-term memory these transitions are fully characterized by a set of rate constants. We consider the question how to extend such a coarse-grained description to non-stationary systems and to systems with finite memory. We identify the physical regimes in which time-dependent rates are meaningful, and state microscopic expressions that can be used to measure both externally time-dependent and history-dependent rates in microscopic simulations. Our description can be used to generalize Markov state models to time-dependent Markovian or non-Markovian systems.
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.
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.
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.
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.
[The state of phospholipase D in solution and its catalytic activity].
Rakhimov, M M; Mad'iarov, Sh R
1977-04-01
Functioning of water-soluble phospholipase D from cotton seeds is studied on two phases contact area (liquid-liquid, liquid-solid substance) and on the surface of mixed lecitine and sodium dodecylsulphate micelles. It is found that water-soluble phospholipase D, which normally has no catalytic activity, is capable to hydrolyse its substrates in the presence of organic solvents, solid adsorbents and sodium dodecylsulphate. The data obtained show that in all the cases studied the activation observed is due to adsorption immobilization of the enzyme. K lambda and K alpha constants are introduced, which are characteristics of immobilyzing ability of agents-matrices for immobilization. Phase transitions, which take place in heterogenous system (enzyme-activator-substrate-water solution), are found to be a necessary condition for the enzyme activation. A hypothesis, that catalytical activity of water-soluble phospholipase D is inherent of the adsorbed enzyme, is discussed on the basis of the data on comparative study of adsorbed and water-soluble enzymes.
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.
NASA Astrophysics Data System (ADS)
Corradini, Dario; Su, Zhiqiang; Stanley, H. Eugene; Gallo, Paola
2012-11-01
We perform molecular dynamics computer simulations in order to study the equation of state and the structure of supercooled aqueous solutions of methanol at methanol mole fractions xm = 0.05 and xm = 0.10. We model the solvent using the TIP4P/2005 potential and the methanol using the OPLS-AA force field. We find that for xm = 0.05 the behavior of the equation of state, studied in the P - T and P - ρ planes, is consistent with the presence of a liquid-liquid phase transition, reminiscent of that previously found for xm = 0. We estimate the position of the liquid-liquid critical point to be at T = 193 K, P = 96 MPa, and ρ = 1.003 g/cm3. When the methanol mole fraction is doubled to xm = 0.10 no liquid-liquid transition is observed, indicating its possible disappearance at this concentration. We also study the water-water and water-methanol structure in the two solutions. We find that down to low temperature methanol can be incorporated into the water structure for both xm = 0.05 and xm = 0.10.
Corradini, Dario; Su, Zhiqiang; Stanley, H Eugene; Gallo, Paola
2012-11-14
We perform molecular dynamics computer simulations in order to study the equation of state and the structure of supercooled aqueous solutions of methanol at methanol mole fractions x(m) = 0.05 and x(m) = 0.10. We model the solvent using the TIP4P/2005 potential and the methanol using the OPLS-AA force field. We find that for x(m) = 0.05 the behavior of the equation of state, studied in the P - T and P - ρ planes, is consistent with the presence of a liquid-liquid phase transition, reminiscent of that previously found for x(m) = 0. We estimate the position of the liquid-liquid critical point to be at T = 193 K, P = 96 MPa, and ρ = 1.003 g/cm(3). When the methanol mole fraction is doubled to x(m) = 0.10 no liquid-liquid transition is observed, indicating its possible disappearance at this concentration. We also study the water-water and water-methanol structure in the two solutions. We find that down to low temperature methanol can be incorporated into the water structure for both x(m) = 0.05 and x(m) = 0.10.
Self-Consistent Solutions for the Scattering State with Two Free Electrons
NASA Astrophysics Data System (ADS)
Hahn, Y. K.; Gau, J. N.; Zerrad, E.
2013-11-01
Wave functions for the scattering states with two free electrons in the field of an ion core are explicitly calculated by the self-consistent, continuum Hartree-Fock (CHF) theory. Typically, such states are associated with the three-body recombination, collisional ionization and photo-double ionization, but have never been directly studied previously. The calculated continuum orbitals are found to be predominantly of the plane-wave forms, as though the system is translation invariant, in the context of many-body HF theory. The symmetry is mildly broken by the presence of the core ion, at about fifteen-percents level, indicating that the orbitals are largely delocalized and the effect of the core potential is an important but minor perturbation. The properties of channel orthogonality and completeness are preserved by the nearly plane wave forms. To test the validity of this finding and the CHF, the continuum orbitals are used to evaluate the amplitudes for the electron impact ionization, and the amputation procedure, that is crucial in the theory, is also critically re-examined.
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.
Perturbation approach to resonator state solution using the Fourier-Bessel numerical solver
NASA Astrophysics Data System (ADS)
Gauthier, Robert C.
2017-02-01
The Fourier-Bessel (FFB) numerical solver is a useful tool for obtaining the steady states of resonator structures that conform to a cylindrical symmetry. Recently the FFB solver has been greatly simplified by reconfiguring the matrix generating expressions using Maxwell's curl expressions rather than the standard wave equations. This presentation provides a numerical framework suitable for the application on non-degenerate perturbation theory within the theoretical structure of the reconfigured FFB computation environment. It is shown that the resonator structure's perturbation contribution can be isolated as a separate matrix which dictates the shift in resonator state properties. Two distinct application examples are provide; the first has the perturbation possess the same rotational symmetry as the original structure and preserves azimuthal mode order families; the second perturbation has a symmetry different than the original structure and promotes a mixing between azimuthal mode order families. The perturbation extension promises to amplify the potential usefulness of the FFB technique when theoretically considering photonic sensors such as whispering-gallery mode, photonic crystal hole infiltration and a host of others in which the measurand undergoes small changes in its optical properties.
NASA Astrophysics Data System (ADS)
Prima, Eka Cahya; Yuliarto, Brian; Suyatman, Dipojono, Hermawan Kresno
2015-09-01
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.
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.
Bhate, Manasi P; Woodard, Jaie C; Mehta, Manish A
2009-07-15
The NMR chemical shift is a sensitive reporter of peptide secondary structure and its solvation environment, and it is potentially rich with information about both backbone dihedral angles and hydrogen bonding. We report results from solution- and solid-state (13)C and (15)N NMR studies of four zwitterionic model dipeptides, L-alanyl-L-alanine, L-alanyl-glycine, glycyl-L-alanine, and glycyl-glycine, in which we attempt to isolate structural and environmental contributions to the chemical shift. We have mapped hydrogen-bonding patterns in the crystalline states of these dipeptides using the published crystal structures and correlated them with (13)C and (15)N magic angle spinning chemical shift data. To aid in the interpretation of the solvated chemical shifts, we performed ab initio quantum chemical calculations to determine the low-energy conformers and their chemical shifts. Assuming low energy barriers to interconversion between thermally accessible conformers, we compare the Boltzmann-averaged chemical shifts with the experimentally determined solvated-state shifts. The results allow us to correlate the observed differences in chemical shifts between the crystalline and solvated states to changes in conformation and hydrogen bonding that occur upon solvation.
String theory extensions of Einstein-Maxwell fields: The stationary case
NASA Astrophysics Data System (ADS)
Herrera-Aguilar, Alfredo; Kechkin, Oleg V.
2004-01-01
We present a new approach for generating solutions in heterotic string theory compactified down to three dimensions on a torus with d+n>2, where d and n stand for the number of compactified space-time dimensions and Abelian gauge fields, respectively. It is shown that in the case when d=2k+1, and n is arbitrary, one can apply a solution-generating procedure which consists of mapping seed solutions of the stationary Einstein theory with k Maxwell fields to the heterotic string realm by using pure field redefinitions. A novel feature of this method is that it is precisely the electromagnetic sector of the stationary electrovacuum that mainly gives rise to a nontrivial multidimensional metric. This approach leads to classes of solutions which are invariant with respect to the total group of three-dimensional charging symmetries of the heterotic string theory, i.e., to all finite transformations which generate charged solutions from neutral ones and preserve the asymptotics of the starting field configurations. As an application of the presented approach we generate a particular extension of the stationary Einstein-multi-Maxwell theory obtained on the basis of the Kerr-multi-Newman-NUT special class of solutions and establish the conditions under which the resulting multi-dimensional metric of the heterotic string theory is asymptotically flat.
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.
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.
Stationary bubbles and their tunneling channels toward trivial geometry
Chen, Pisin; Yeom, Dong-han; Domènech, Guillem; Sasaki, Misao E-mail: guillem.domenech@yukawa.kyoto-u.ac.jp E-mail: innocent.yeom@gmail.com
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.
Stationary bubbles and their tunneling channels toward trivial geometry
Chen, Pisin; Domènech, Guillem; Sasaki, Misao; ...
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
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 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. Ultimately, this may provide a resolution to the information loss dilemma.
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)
Garikipati, K.; Olberding, J. E.; Narayanan, H.; Arruda, E. M.; Grosh, K.; Calve, S.
2006-07-01
Remodelling is defined as an evolution of microstructure or variations in the configuration of the underlying manifold. The manner in which a biological tissue and its subsystems remodel their structure is treated in a continuum mechanical setting. While some examples of remodelling are conveniently modelled as evolution of the reference configuration—Case I—others are more suited to an internal variable description—Case II. In this paper, we explore the applicability of stationary energy states to remodelled systems. A variational treatment is introduced by assuming that stationary energy states are attained by changes in microstructure via one of the two mechanisms—Cases I and II. The configurational change of a long-chain molecule is presented as an example of Case I, and collagen fibre reorientation in in vitro tissue constructs as an example of Case II. The second example is further studied for its thermodynamic dissipation characteristics. This leads to an important finding on the limitation of purely mechanical treatments of some types of remodelling phenomena.
The Northern Hemisphere winter stationary wave response to global warming in CMIP5
NASA Astrophysics Data System (ADS)
Simpson, Isla; Seager, Richard; Ting, Mingfang; Shaw, Tiffany
2015-04-01
During the Northern Hemisphere winter, models tend to predict a poleward shifting of the zonal mean mid-latitude westerlies under anthropogenic greenhouse gas emissions. Locally, however, changes in the stationary waves tend to dominate, resulting in considerable deviation from this around the longitude circle, with important implications for regional climate change. Past studies have demonstrated diversity in the stationary wave response to global warming and differ in their views of the mechanisms involved in producing it. Here we will explore the stationary wave response to global warming in the CMIP5 dataset and demonstrate a strong consensus on a wavenumber 5 stationary wave response with a particular phasing that contributes to hydroclimate change across North America and Europe, such as wetting on the west coast of the USA, drying in the south west USA and drying in the eastern Mediterranean. The mechanisms responsible for producing this multi-model mean response are explored using a stationary wave model. It is demonstrated that, to first order, it is produced by changes in the zonal mean basic state, in agreement with the majority of previous stationary wave modelling studies. The relative importance of different features of this basic state change such as Arctic amplification, enhanced tropical upper tropospheric warming, stratospheric cooling and their associated zonal mean zonal wind responses will be explored. Through an understanding of the mechanisms involved in this stationary wave response we can begin to assess our confidence in whether the real world will behave as the models do and understand any diversity among the modelled responses.
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.
Linear stability of ideal MHD configurations. II. Results for stationary equilibrium configurations
NASA Astrophysics Data System (ADS)
Demaerel, T.; Keppens, R.
2016-12-01
In this paper, we continue exploring the consequences of the general equation of motion (EOM) governing all Lagrangian perturbations ξ about a time-dependent, ideal magnetohydrodynamic (MHD) configuration, which includes self-gravity, external gravity, pressure gradients, compressibility, inertial effects, and anisotropic Lorentz force. We here address the specific case of MHD stability for 3D stationary equilibria, where the perturbed EOM features a symmetric operator F and an antisymmetric Doppler-Coriolis operator v . ∇ . For this case, we state and prove the general properties for the solutions ξ of the governing dynamical system. For axisymmetric perturbations about axisymmetric equilibria with purely toroidal, or purely poloidal magnetic fields, specific stability theorems can be formulated. We derive a useful integral expression for the quadratic quantity given by the inner product ⟨ ξ , F [ ξ ] ⟩ . For deriving stability statements on MHD states where self-gravity is involved as well, we provide an upper bound on the perturbed self-gravitational energy associated with the displacement ξ . The resulting expression elucidates the role of potentially stabilizing versus destabilizing contributions and shows the role of gravity, entropy gradients, velocity shear, currents, Lorentz forces, inertia, and pressure gradients in offering many routes to unstable behavior in flowing gases and plasmas. These have historically mostly been studied for static v = 0 configurations, looking at stability of exactly force-balanced states, or by assuming stationarity similar to our approach here (i.e., ∂ t ≡ 0 for the state we perturb), but typically in combination with some reduced dimensionality on the configuration of interest (translational or axisymmetry). We show that in these limits, we find and generalize expressions well-known from, e.g., the study of ideal MHD stability of tokamak plasmas or from Schwarzschild's criteria controlling convection in
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
Framework for Assessing Biogenic CO2 Emissions from Stationary Sources
This revision of the 2011 report, Accounting Framework for Biogenic CO2 Emissions from Stationary Sources, evaluates biogenic CO2 emissions from stationary sources, including a detailed study of the scientific and technical issues associated with assessing biogenic carbon dioxide...
2012-10-19
On September 18, 2012, the Tennessee Department of Health was alerted by a clinician regarding a patient with culture-confirmed Aspergillus fumigatus meningitis diagnosed 46 days after epidural steroid injection at a Tennessee ambulatory surgical center. By September 27, the initial investigation, carried out by the Tennessee Department of Health in collaboration with CDC and the North Carolina Department of Health and Human Services, had identified an additional eight patients with clinically diagnosed, culture-negative meningitis: seven in Tennessee and one in North Carolina. All nine patients had received epidural steroid injection with preservative-free methylprednisolone acetate solution (MPA), compounded at New England Compounding Center (NECC) in Framingham, Massachusetts. All nine patients had received one or more injections from three lots of MPA (lot numbers 05212012@68; 06292012@26; and 08102012@51). As of October 10, a multistate investigation led by CDC in collaboration with state and local health departments and the Food and Drug Administration (FDA) had identified 137 cases and 12 deaths associated with this outbreak in 10 states. Active case-finding efforts and extensive investigation into medications and medication lot numbers received by patients have confirmed that, as of October 10, no cases were associated with other lots of MPA, nor were any associated with other NECC products. This report describes the ongoing investigation by CDC and state and local health departments, and includes important recommendations for physicians and patients.
Shrestha, Sachin Man Bajimaya; Joldes, Grand Roman; Wittek, Adam; Miller, Karol
2013-04-01
We model complete growth of an avascular tumour by employing cellular automata for the growth of cells and steady-state equation to solve for nutrient concentrations. Our modelling and computer simulation results show that, in the case of a brain tumour, oxygen distribution in the tumour volume may be sufficiently described by a time-independent steady-state equation without losing the characteristics of a time-dependent diffusion equation. This makes the solution of oxygen concentration in the tumour volume computationally more efficient, thus enabling simulation of tumour growth on a large scale. We solve this steady-state equation using a central difference method. We take into account the composition of cells and intercellular adhesion in addition to processes involved in cell cycle--proliferation, quiescence, apoptosis, and necrosis--in the tumour model. More importantly, we consider cell mutation that gives rise to different phenotypes and therefore a tumour with heterogeneous population of cells. A new phenotype is probabilistically chosen and has the ability to survive at lower levels of nutrient concentration and reproduce faster. We show that heterogeneity of cells that compose a tumour leads to its irregular growth and that avascular growth is not supported for tumours of diameter above 18 mm. We compare results from our growth simulation with existing experimental data on Ehrlich ascites carcinoma and tumour spheroid cultures and show that our results are in good agreement with the experimental findings.