WorldWideScience

Sample records for stable periodic solutions

  1. Periodicity of the stable isotopes

    CERN Document Server

    Boeyens, J C A

    2003-01-01

    It is demonstrated that all stable (non-radioactive) isotopes are formally interrelated as the products of systematically adding alpha particles to four elementary units. The region of stability against radioactive decay is shown to obey a general trend based on number theory and contains the periodic law of the elements as a special case. This general law restricts the number of what may be considered as natural elements to 100 and is based on a proton:neutron ratio that matches the golden ratio, characteristic of biological and crystal growth structures. Different forms of the periodic table inferred at other proton:neutron ratios indicate that the electronic configuration of atoms is variable and may be a function of environmental pressure. Cosmic consequences of this postulate are examined. (author)

  2. Time—periodic weak solutions

    Directory of Open Access Journals (Sweden)

    Eliana Henriques de Brito

    1990-01-01

    Full Text Available In continuing from previous papers, where we studied the existence and uniqueness of the global solution and its asymptotic behavior as time t goes to infinity, we now search for a time-periodic weak solution u(t for the equation whose weak formulation in a Hilbert space H isddt(u′,v+δ(u′,v+αb(u,v+βa(u,v+(G(u,v=(h,vwhere: ′=d/dt; (′ is the inner product in H; b(u,v, a(u,v are given forms on subspaces U⊂W, respectively, of H; δ>0, α≥0, β≥0 are constants and α+β>0; G is the Gateaux derivative of a convex functional J:V⊂H→[0,∞ for V=U, when α>0 and V=W when α=0, hence β>0; v is a test function in V; h is a given function of t with values in H.

  3. Photolysis of Periodate and Periodic Acid in Aqueous Solution

    DEFF Research Database (Denmark)

    Sehested, Knud; Kläning, U. K.

    1978-01-01

    The photochemistry of periodate and periodic acid in aqueous solution was studied (i) by quantum yield measurements at low light intensity (ii) by flash photolysis, and (iii) by photolysis of glassy samples at 77 K. The photochemical studies were supplemented with pulse radiolysis studies...... of aqueous periodate solutions and with kinetic studies using stopped-flow technique. In strongly alkaline solution the photodecomposition of periodate proceeds via formation of O– and IVI. At pH

  4. Discontinuous Spirals of Stable Periodic Oscillations

    DEFF Research Database (Denmark)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase...

  5. On exponential stability and periodic solutions of CNNs with delays

    Science.gov (United States)

    Cao, Jinde

    2000-03-01

    In this Letter, the author analyses further problems of global exponential stability and the existence of periodic solutions of cellular neural networks with delays (DCNNs). Some simple and new sufficient conditions are given ensuring global exponential stability and the existence of periodic solutions of DCNNs by applying some new analysis techniques and constructing suitable Lyapunov functionals. These conditions have important leading significance in the design and applications of globally stable DCNNs and periodic oscillatory DCNNs and are weaker than those in the earlier works [Phys. Rev. E 60 (1999) 3244], [J. Comput. Syst. Sci. 59 (1999)].

  6. Unique solution to periodic boundary value problems

    Directory of Open Access Journals (Sweden)

    Yong Sun

    1991-01-01

    Full Text Available Existence of unique solution to periodic boundary value problems of differential equations with continuous or discontinuous right-hand side is considered by utilizing the method of lower and upper solutions and the monotone properties of the operator. This is subject to discussion in the present paper.

  7. PERIODIC-SOLUTIONS IN SPONTANEOUSLY BROKEN THEORIES

    NARCIS (Netherlands)

    BRIHAYE, Y; KUNZ, J

    A class of spontaneously broken field theories is proposed, and the occurrence of their periodic, classical solutions is investigated in detail. The emergence of multiple solutions is observed, their normal modes of oscillation are studied, and the bifurcations of the classical energy functional are

  8. Periodic Solutions and S-Asymptotically Periodic Solutions to Fractional Evolution Equations

    Directory of Open Access Journals (Sweden)

    Jia Mu

    2017-01-01

    Full Text Available This paper deals with the existence and uniqueness of periodic solutions, S-asymptotically periodic solutions, and other types of bounded solutions for some fractional evolution equations with the Weyl-Liouville fractional derivative defined for periodic functions. Applying Fourier transform we give reasonable definitions of mild solutions. Then we accurately estimate the spectral radius of resolvent operator and obtain some existence and uniqueness results.

  9. Periodic solutions of dissipative systems revisited

    Directory of Open Access Journals (Sweden)

    Lech Górniewicz

    2006-05-01

    Full Text Available We reprove in an extremely simple way the classical theorem that time periodic dissipative systems imply the existence of harmonic periodic solutions, in the case of uniqueness. We will also show that, in the lack of uniqueness, the existence of harmonics is implied by uniform dissipativity. The localization of starting points and multiplicity of periodic solutions will be established, under suitable additional assumptions, as well. The arguments are based on the application of various asymptotic fixed point theorems of the Lefschetz and Nielsen type.

  10. Periodic solutions of dissipative systems revisited

    Directory of Open Access Journals (Sweden)

    Górniewicz Lech

    2006-01-01

    Full Text Available We reprove in an extremely simple way the classical theorem that time periodic dissipative systems imply the existence of harmonic periodic solutions, in the case of uniqueness. We will also show that, in the lack of uniqueness, the existence of harmonics is implied by uniform dissipativity. The localization of starting points and multiplicity of periodic solutions will be established, under suitable additional assumptions, as well. The arguments are based on the application of various asymptotic fixed point theorems of the Lefschetz and Nielsen type.

  11. Almost periodic solutions of impulsive differential equations

    CERN Document Server

    Stamov, Gani T

    2012-01-01

    Impulsive differential equations are suitable for the mathematical simulation of evolutionary processes in which the parameters undergo relatively long periods of smooth variation followed by short-term rapid changes (that is, jumps) in their values. Processes of this type are often investigated in various fields of science and technology. The question of the existence and uniqueness of almost periodic solutions of differential equations is an age-old problem of great importance. The qualitative theory of impulsive differential equations is currently undergoing rapid development in relation to the investigation of various processes which are subject to impacts during their evolution, and many findings on the existence and uniqueness of almost periodic solutions of these equations are being made. This book systematically presents findings related to almost periodic solutions of impulsive differential equations and illustrates their potential applications.

  12. Periodic Solutions of Hamiltonian Systems: A Survey.

    Science.gov (United States)

    1980-12-01

    establishing the existence of periodic solutions of such systems. DD 3 1473 ED.T-ON LF I NOV 11 IS OUSOLETE UNC~ LASSI FIED ,. ec .oy r, i ~ bt lll u I.’ 1 -1.1t PA;- fWho Doe I neo**JI DATE ’ILMED,’

  13. Exact solutions, energy, and charge of stable Q-balls

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Marques, M.A. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil); Menezes, R. [Universidade Federal da Paraiba, Departamento de Ciencias Exatas, Rio Tinto, PB (Brazil); Universidade Federal de Campina Grande, Departamento de Fisica, Campina Grande, PB (Brazil)

    2016-05-15

    In this work we deal with nontopological solutions of the Q-ball type in two spacetime dimensions. We study models of current interest, described by a Higgs-like and other, similar potentials which unveil the presence of exact solutions. We use the analytic results to investigate how to control the energy and charge to make the Q-balls stable. (orig.)

  14. Periodic Solutions for a Delayed Population Model on Time Scales

    OpenAIRE

    Kejun Zhuang; Zhaohui Wen

    2010-01-01

    This paper deals with a delayed single population model on time scales. With the assistance of coincidence degree theory, sufficient conditions for existence of periodic solutions are obtained. Furthermore, the better estimations for bounds of periodic solutions are established.

  15. Periodic Solutions of a System of Delay Differential Equations for a Small Delay

    Directory of Open Access Journals (Sweden)

    Adu A.M. Wasike

    2002-06-01

    Full Text Available We prove the existence of an asymptotically stable periodic solution of a system of delay differential equations with a small time delay t > 0. To achieve this, we transform the system of equations into a system of perturbed ordinary differential equations and then use perturbation results to show the existence of an asymptotically stable periodic solution. This approach is contingent on the fact that the system of equations with t = 0 has a stable limit cycle. We also provide a comparative study of the solutions of the original system and the perturbed system.  This comparison lays the ground for proving the existence of periodic solutions of the original system by Schauder's fixed point theorem.

  16. Periodic solutions of nonautonomous differential systems modeling obesity population

    International Nuclear Information System (INIS)

    Arenas, Abraham J.; Gonzalez-Parra, Gilberto; Jodar, Lucas

    2009-01-01

    In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.

  17. Periodic solutions of nonautonomous differential systems modeling obesity population

    Energy Technology Data Exchange (ETDEWEB)

    Arenas, Abraham J. [Departamento de Matematicas y Estadistica, Universidad de Cordoba Monteria (Colombia)], E-mail: aarenas@sinu.unicordoba.edu.co; Gonzalez-Parra, Gilberto [Departamento de Calculo, Universidad de los Andes, Merida (Venezuela, Bolivarian Republic of)], E-mail: gcarlos@ula.ve; Jodar, Lucas [Instituto de Matematica Multidisciplinar, Universidad Politecnica de Valencia Edificio 8G, 2o, 46022 Valencia (Spain)], E-mail: ljodar@imm.upv.es

    2009-10-30

    In this paper we study the periodic behaviour of the solutions of a nonautonomous model for obesity population. The mathematical model represented by a nonautonomous system of nonlinear ordinary differential equations is used to model the dynamics of obese populations. Numerical simulations suggest periodic behaviour of subpopulations solutions. Sufficient conditions which guarantee the existence of a periodic positive solution are obtained using a continuation theorem based on coincidence degree theory.

  18. Numerical approximation of random periodic solutions of stochastic differential equations

    Science.gov (United States)

    Feng, Chunrong; Liu, Yu; Zhao, Huaizhong

    2017-10-01

    In this paper, we discuss the numerical approximation of random periodic solutions of stochastic differential equations (SDEs) with multiplicative noise. We prove the existence of the random periodic solution as the limit of the pull-back flow when the starting time tends to -∞ along the multiple integrals of the period. As the random periodic solution is not explicitly constructible, it is useful to study the numerical approximation. We discretise the SDE using the Euler-Maruyama scheme and modified Milstein scheme. Subsequently, we obtain the existence of the random periodic solution as the limit of the pull-back of the discretised SDE. We prove that the latter is an approximated random periodic solution with an error to the exact one at the rate of √{Δ t} in the mean square sense in Euler-Maruyama method and Δ t in the Milstein method. We also obtain the weak convergence result for the approximation of the periodic measure.

  19. Stability of stationary and periodic solutions equations in Banach space

    Directory of Open Access Journals (Sweden)

    A. Ya. Dorogovtsev

    1997-01-01

    Full Text Available Linear difference and differential equations with operator coefficients and random stationary (periodic input are considered. Conditions are presented for the mean stability of stationary (periodic solutions under small perturbation of the coefficients.

  20. Relaxation periodic solutions of one singular perturbed system with delay

    Science.gov (United States)

    Kashchenko, A. A.

    2017-12-01

    In this paper, we consider a singularly perturbed system of two differential equations with delay, simulating two coupled oscillators with a nonlinear compactly supported feedback. We reduce studying nonlocal dynamics of initial system to studying dynamics of special finite-dimensional mappings: rough stable (unstable) cycles of these mappings correspond to exponentially orbitally stable (unstable) relaxation solutions of initial problem. We show that dynamics of initial model depends on coupling coefficient crucially. Multistability is proved.

  1. Occurrence of stable periodic modes in a pendulum with cubic ...

    Indian Academy of Sciences (India)

    The effect of parametric modulation and secondary har- monic forcing in this transition have been analyzed in detail and reported earlier by the authors [5,7]. ... In the present work, the crossover from periodicity to chaos is discussed with a detailed .... value of q2 above which only resonance can take place is given by q.

  2. Quasi-periodic solutions of the Boomeron equation

    NARCIS (Netherlands)

    Martini, Ruud; Wesselius, W.

    1985-01-01

    The quasi-periodic solutions for the Boomeron equation are determined by means of function-theoretical methods related to Riemann surfaces and theta functions. Also determined are the so-called Boomerons as degenerations of the quasi-periodic solutions. Moreover it is indicated that there are no

  3. Nontrivial Periodic Solutions for Nonlinear Second-Order Difference Equations

    Directory of Open Access Journals (Sweden)

    Tieshan He

    2011-01-01

    Full Text Available This paper is concerned with the existence of nontrivial periodic solutions and positive periodic solutions to a nonlinear second-order difference equation. Under some conditions concerning the first positive eigenvalue of the linear equation corresponding to the nonlinear second-order equation, we establish the existence results by using the topological degree and fixed point index theories.

  4. Periodic and subharmonic solutions for second order p-Laplacian ...

    Indian Academy of Sciences (India)

    of periodic and subharmonic solutions to second order p-Laplacian difference equa- tions are obtained by using the critical point theory. The proof is based on the Linking theorem in combination with variational technique. Keywords. Periodic and subharmonic solutions; p-Laplacian; difference equations; discrete variational ...

  5. Existence of extremal periodic solutions for quasilinear parabolic equations

    Directory of Open Access Journals (Sweden)

    Siegfried Carl

    1997-01-01

    bounded domain under periodic Dirichlet boundary conditions. Our main goal is to prove the existence of extremal solutions among all solutions lying in a sector formed by appropriately defined upper and lower solutions. The main tools used in the proof of our result are recently obtained abstract results on nonlinear evolution equations, comparison and truncation techniques and suitably constructed special testfunction.

  6. Large time periodic solutions to coupled chemotaxis-fluid models

    Science.gov (United States)

    Jin, Chunhua

    2017-12-01

    In this paper, we deal with the time periodic problem to coupled chemotaxis-fluid models. We prove the existence of large time periodic strong solutions for the full chemotaxis-Navier-Stokes system in spatial dimension N=2, and the existence of large time periodic strong solutions for the chemotaxis-Stokes system in spatial dimension N=3. On the basis of these, the regularity of the solutions can be further improved. More precisely speaking, if the time periodic source g and the potential force \

  7. Periodic and almost periodic solutions for multi-valued differential equations in Banach spaces

    Directory of Open Access Journals (Sweden)

    E. Hanebaly

    2000-03-01

    Full Text Available It is known that for $omega$-periodic differential equations of monotonous type, in uniformly convex Banach spaces, the existence of a bounded solution on ${Bbb R}^+$ is equivalent to the existence of an omega-periodic solution (see Haraux [5] and Hanebaly [7, 10]. It is also known that if the Banach space is strictly convex and the equation is almost periodic and of monotonous type, then the existence of a continuous solution with a precompact range is equivalent to the existence of an almost periodic solution (see Hanebaly [8]. In this note we want to generalize the results above for multi-valued differential equations.

  8. Estimates on the minimal period for periodic solutions of nonlinear second order Hamiltonian systems

    International Nuclear Information System (INIS)

    Yiming Long.

    1994-11-01

    In this paper, we prove a sharper estimate on the minimal period for periodic solutions of autonomous second order Hamiltonian systems under precisely Rabinowitz' superquadratic condition. (author). 20 refs, 1 fig

  9. Time-periodic solutions of the Benjamin-Ono equation

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose , D.M.; Wilkening, Jon

    2008-04-01

    We present a spectrally accurate numerical method for finding non-trivial time-periodic solutions of non-linear partial differential equations. The method is based on minimizing a functional (of the initial condition and the period) that is positive unless the solution is periodic, in which case it is zero. We solve an adjoint PDE to compute the gradient of this functional with respect to the initial condition. We include additional terms in the functional to specify the free parameters, which, in the case of the Benjamin-Ono equation, are the mean, a spatial phase, a temporal phase and the real part of one of the Fourier modes at t = 0. We use our method to study global paths of non-trivial time-periodic solutions connecting stationary and traveling waves of the Benjamin-Ono equation. As a starting guess for each path, we compute periodic solutions of the linearized problem by solving an infinite dimensional eigenvalue problem in closed form. We then use our numerical method to continue these solutions beyond the realm of linear theory until another traveling wave is reached (or until the solution blows up). By experimentation with data fitting, we identify the analytical form of the solutions on the path connecting the one-hump stationary solution to the two-hump traveling wave. We then derive exact formulas for these solutions by explicitly solving the system of ODE's governing the evolution of solitons using the ansatz suggested by the numerical simulations.

  10. Periodic solution for the stochastic chemostat with general response function

    Science.gov (United States)

    Wang, Liang; Jiang, Daqing

    2017-11-01

    This paper addresses a stochastic chemostat model with periodic dilution rate and general class of response functions. The general functional response is assumed to satisfy two classifications of conditions, and these assumptions on the functional response are relative weak that are valid for many forms of growth response. For the chemostat with periodic dilution rate, we derive the sufficient criteria for the existence of the stochastic nontrivial positive periodic solution, by utilizing Khasminskii's theory on periodic Markov process.

  11. Periodic and subharmonic solutions for second order p-Laplacian ...

    Indian Academy of Sciences (India)

    Periodic and subharmonic solutions; -Laplacian; difference equations; discrete variational theory. ... Packaging Engineering Institute, Jinan University, Zhuhai 519070, People's Republic of China; College of Mathematics and Information Sciences, Guangzhou University, Guangzhou 510006, People's Republic of China ...

  12. On periodic solutions to second-order Duffing type equations

    Czech Academy of Sciences Publication Activity Database

    Lomtatidze, Alexander; Šremr, Jiří

    2018-01-01

    Roč. 40, April (2018), s. 215-242 ISSN 1468-1218 Institutional support: RVO:67985840 Keywords : periodic solution * Duffing type equation * positive solution Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 1.659, year: 2016 http://www.sciencedirect.com/science/article/pii/S1468121817301335?via%3Dihub

  13. Periodic and solitary wave solutions of cubic–quintic nonlinear ...

    Indian Academy of Sciences (India)

    physics pp. 1253–1258. Periodic and solitary wave solutions of cubic–quintic nonlinear reaction-diffusion equation with variable convection coefficients. S B BHARDWAJ1,2,∗ ... 3Department of Mathematics, National Institute of Technology, Delhi 110 040, India. 4Department of .... 3.1 Fractional transform soliton solutions.

  14. Perturbation method for periodic solutions of nonlinear jerk equations

    International Nuclear Information System (INIS)

    Hu, H.

    2008-01-01

    A Lindstedt-Poincare type perturbation method with bookkeeping parameters is presented for determining accurate analytical approximate periodic solutions of some third-order (jerk) differential equations with cubic nonlinearities. In the process of the solution, higher-order approximate angular frequencies are obtained by Newton's method. A typical example is given to illustrate the effectiveness and simplicity of the proposed method

  15. On periodic solutions to second-order Duffing type equations

    Czech Academy of Sciences Publication Activity Database

    Lomtatidze, Alexander; Šremr, Jiří

    2018-01-01

    Roč. 40, April (2018), s. 215-242 ISSN 1468-1218 Institutional support: RVO:67985840 Keywords : periodic solution * Duffing type equation * positive solution Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 1.659, year: 2016 http://www. science direct.com/ science /article/pii/S1468121817301335?via%3Dihub

  16. Existence of periodic solutions for a semilinear ordinary differential equation

    Directory of Open Access Journals (Sweden)

    Petr Girg

    1998-11-01

    Full Text Available Dancer [3] found a necessary and sufficient condition for the existence of periodic solutions to the equation $$ ddot x +g_1(dot x + g_0(x = f(t,.$$ His condition is based on a functional that depends on the solution to the above equation with $g_0=0$. However, that solution is not always explicitly known which makes the condition unverifiable in practical situations. As an alternative, we find computable bounds for the functional that provide a sufficient condition and a necessary condition for the existence of solutions.

  17. Stabilization of Periodic Solutions in a Thedered Satellite System by Damping Injection

    DEFF Research Database (Denmark)

    Larsen, Martin Birkelund; Blanke, Mogens

    2009-01-01

    to affect the orbit parameters. An approximation of the periodic solutions of the closed loop system is found as a series expansion in the parameter plane spanned by the controller gain and the bias term. The stability of the solutions is investigated using linear Floquet analysis of the variational...... presents a control design for stabilizing these periodic solutions. The design consists of a control law for stabilising the open-loo equibrilibrium and a bias term which forces the system trajectory away from the equilibrium. The tether needs to be positioned away from open-loop equilibrium for the tether...... equation and the region of stable periodic solutions in the parameter plane is found....

  18. Calculation of period processing solution syrup in vacuum apparatus

    Directory of Open Access Journals (Sweden)

    A. A. Slavyanskii

    2016-01-01

    Full Text Available Important and crucial element in the management of the technological flow of production of sugar product standards is the period of time the enrichment of massecuite, since its neutralization in the process of crystal formation in vacuum apparatus, excess sugar solution. Although currently proposed and implemented in the industry, including as a front-end accompany the process, a number of ways in the real world sugar production in many cases have to resort to the services of an experienced operator. It is obvious that in any case it is necessary to have a surround-dependent glucose solution data on time for the excess sugar solution into the vacuum apparatus. With regard to the period of the enrichment of depleted sucrose solution are entered into this substance excess sucrose solution, it should be noted that this problem is theoretically still insufficiently developed. It is obvious that for practical purposes it is desirable to have a simple and convenient for engineering calculation of sugar processing time dependencies of the specified volume of water from the operating parameters of the process (the required concentration of sucrose, temperature of the solution stirring. The problem is the quantitative analysis of sucrose crystallization in vacuum apparatus, including the timing of enrichment solution to the excess syrup, period of time processing massecuite total this apparatus has been investigated in many works. However, due to its importance to the task of obtaining commercial sugar high standards this issue required further in-depth examination. In the article to support the enrichment process solution sucrose due to neutralize this solvent system in vacuum apparatus, from the standpoint of diffusion theory provides a more reasonable compared to known so far, quantitative analysis of this process. Where as sucrose crystals team are considering a system of balls, uniformly distributed in vacuum apparatus. On the basis of the solution

  19. Solution Methods for the Periodic Petrol Station Replenishment Problem

    Directory of Open Access Journals (Sweden)

    C Triki

    2013-12-01

    Full Text Available In this paper we introduce the Periodic Petrol Station Replenishment Problem (PPSRP over a T-day planning horizon and describe four heuristic methods for its solution. Even though all the proposed heuristics belong to the common partitioning-then-routing paradigm, they differ in assigning the stations to each day of the horizon. The resulting daily routing problems are then solved exactly until achieving optimalization. Moreover, an improvement procedure is also developed with the aim of ensuring a better quality solution. Our heuristics are tested and compared in two real-life cases, and our computational results show encouraging improvements with respect to a human planning solution

  20. On the solution of high order stable time integration methods

    Czech Academy of Sciences Publication Activity Database

    Axelsson, Owe; Blaheta, Radim; Sysala, Stanislav; Ahmad, B.

    2013-01-01

    Roč. 108, č. 1 (2013), s. 1-22 ISSN 1687-2770 Institutional support: RVO:68145535 Keywords : evolution equations * preconditioners for quadratic matrix polynomials * a stiffly stable time integration method Subject RIV: BA - General Mathematics Impact factor: 0.836, year: 2013 http://www.boundaryvalueproblems.com/content/2013/1/108

  1. Sharp bounds for periodic solutions of Lipschitzian differential equations

    International Nuclear Information System (INIS)

    Zevin, A A

    2009-01-01

    A general system of Lipschitzian differential equations, containing simultaneously terms without delay and with arbitrary constant and time-varying delays, is considered. For the autonomous case, a lower bound for the period of nonconstant periodic solutions, expressed in the respective supremum Lipschitz constants, is found. For nonautonomous periodic equations, explicit upper bounds for the amplitudes and maximum derivatives of periodic solutions are obtained. For all n ≥ 2, the bounds do not depend on n and, in general, are different from that for n = 1. All the bounds are sharp; they are attained in linear differential equations with piece-wise constant deviating arguments. A relation between the obtained bounds and the sharp bounds in other metrics is established

  2. Periodic solutions to second-order indefinite singular equations

    Czech Academy of Sciences Publication Activity Database

    Hakl, Robert; Zamora, M.

    2017-01-01

    Roč. 263, č. 1 (2017), s. 451-469 ISSN 0022-0396 Institutional support: RVO:67985840 Keywords : degree theory * indefinite singularity * periodic solution * singular differential equation Subject RIV: BA - General Mathematics OBOR OECD: Pure mathematics Impact factor: 1.988, year: 2016 http://www.sciencedirect.com/science/article/pii/S0022039617301134

  3. Solitary wave and periodic wave solutions for Burgers, Fisher ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 85; Issue 1. Solitary wave and periodic wave solutions for Burgers, Fisher, Huxley and combined forms of these equations by the (′/)-expansion method. Jalil Manafian Mehrdad Lakestani. Volume 85 Issue 1 July 2015 pp 31-52 ...

  4. Periodic and solitary wave solutions of cubic–quintic nonlinear ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 86; Issue 6. Periodic and solitary wave solutions of cubic–quintic nonlinear reaction-diffusion equation with variable convection coefficients. BHARDWAJ S B SINGH RAM MEHAR SHARMA KUSHAL MISHRA S C. Regular Volume 86 Issue 6 June 2016 pp 1253-1258 ...

  5. Quasi-Periodic Response Solutions at Normal-Internal Resonances

    CERN Document Server

    Broer, H W; Jorba, Angel; Villanueva, J R; Wagener, F

    2003-01-01

    In the conservative dynamics of certain quasi-periodically forced oscillators, normal-internal resonances are considered in a bifurcational setting. The unforced system is a one degree of freedom oscillator, under forcing the system becomes a skew-product flow with a quasi-periodic motion on an $n$-dimensional torus as driving system. In this work, we investigate the persistence and the bifurcations of quasi-periodic $n$-dimensional tori (so-called `response solutions') in the averaged system, filling normal-internal resonance `gaps' that had been excluded in previous analyses.

  6. About Global Stable of Solutions of Logistic Equation with Delay

    Science.gov (United States)

    Kaschenko, S. A.; Loginov, D. O.

    2017-12-01

    The article is devoted to the definition of all the arguments for which all positive solutions of logistic equation with delay tend to zero for t → ∞. The authors have proved the acquainted Wright’s conjecture on evaluation of a multitude of such arguments. An approach that enables subsequent refinement of this evaluation has been developed.

  7. Bifurcation of Periodic Solutions of the Mackey– Glass Equation

    OpenAIRE

    E. P. Kubyshkin; A. R. Moryakova

    2016-01-01

    We study the bifurcation of the equilibrium states of periodic solutions for the Mackey– Glass equation. This equation is considered as a mathematical model of changes in the density of white blood cells. The equation written in dimensionless variables contains a small parameter at the derivative, which makes it singular. We applied the method of uniform normalization, which allows us to reduce the study of the solutions behavior in the neighborhood of the equilibrium state to the analysis of...

  8. Stable one-dimensional periodic waves in Kerr-type saturable and quadratic nonlinear media

    Energy Technology Data Exchange (ETDEWEB)

    Kartashov, Yaroslav V [ICFO-Institut de Ciencies Fotoniques, and Department of Signal Theory and Communications, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain); Egorov, Alexey A [Physics Department, M V Lomonosov Moscow State University, 119899, Moscow (Russian Federation); Vysloukh, Victor A [Departamento de Fisica y Matematicas, Universidad de las Americas-Puebla, Santa Catarina Martir, 72820, Puebla, Cholula (Mexico); Torner, Lluis [ICFO-Institut de Ciencies Fotoniques, and Department of Signal Theory and Communications, Universitat Politecnica de Catalunya, E-08034 Barcelona (Spain)

    2004-05-01

    We review the latest progress and properties of the families of bright and dark one-dimensional periodic waves propagating in saturable Kerr-type and quadratic nonlinear media. We show how saturation of the nonlinear response results in the appearance of stability (instability) bands in a focusing (defocusing) medium, which is in sharp contrast with the properties of periodic waves in Kerr media. One of the key results discovered is the stabilization of multicolour periodic waves in quadratic media. In particular, dark-type waves are shown to be metastable, while bright-type waves are completely stable in a broad range of energy flows and material parameters. This yields the first known example of completely stable periodic wave patterns propagating in conservative uniform media supporting bright solitons. Such results open the way to the experimental observation of the corresponding self-sustained periodic wave patterns.

  9. Exact periodic wave solutions to the generalized Nizhnik–Novikov ...

    Indian Academy of Sciences (India)

    f(ξ) = tanh ξ, g(ξ) = sech ξ, and the method is called the two-family truncation method [11,12]. It is worth noticing that when Bi ... its many doubly periodic wave solutions and study their limit cases. Substituting u = u(ξ),v = v(ξ),w = w(ξ),ξ = kx + ly ..... ematical Society, Providence, 1997). [11] R Conte and M Musette, Physica D69, ...

  10. Almost Periodic Solutions for Impulsive Fractional Stochastic Evolution Equations

    Directory of Open Access Journals (Sweden)

    Toufik Guendouzi

    2014-08-01

    Full Text Available In this paper, we consider the existence of square-mean piecewise almost periodic solutions for impulsive fractional stochastic evolution equations involving Caputo fractional derivative. The main results are obtained by means of the theory of operators semi-group, fractional calculus, fixed point technique and stochastic analysis theory and methods adopted directly from deterministic fractional equations. Some known results are improved and generalized.

  11. Periodic solutions in reaction–diffusion equations with time delay

    International Nuclear Information System (INIS)

    Li, Li

    2015-01-01

    Spatial diffusion and time delay are two main factors in biological and chemical systems. However, the combined effects of them on diffusion systems are not well studied. As a result, we investigate a nonlinear diffusion system with delay and obtain the existence of the periodic solutions using coincidence degree theory. Moreover, two numerical examples confirm our theoretical results. The obtained results can also be applied in other related fields

  12. Almost periodic solution of shunting inhibitory CNNs with delays

    Science.gov (United States)

    Chen, Anping; Cao, Jinde

    2002-06-01

    Using the Banach fixed point theorem, we obtain a sufficient condition for the existence of almost periodic solution of shunting inhibitory cellular neural networks {dx ij}/{dt}=-a ijx ij- limit∑C kl∈N r(i,j) C ijklf x kl(t-τ) x ij+L ij(t), the global attractivity of SICNNs is also obtained. An example is given to illustrate that the condition of our results are feasible.

  13. Periodic solutions to systems of reaction-diffusion equations

    Science.gov (United States)

    Rosen, G.

    1976-01-01

    Necessary and sufficient conditions are derived for the existence of temporally periodic 'dissipative structure' solutions in weak diffusion with the reaction rate terms dominant in a generic system of reaction-diffusion differential equations. The enumerator index i of the equations denotes the density or concentration of the ith participating molecular or biological species, and D sub i is the diffusivity constant for the ith species while Q sub i (c), an algebraic function of the n-tuple c, expresses the local rate of production of the ith species due to chemical reactions or biological interactions.

  14. Asymptotically flat, stable black hole solutions in Einstein-Yang-Mills-Chern-Simons theory.

    Science.gov (United States)

    Brihaye, Yves; Radu, Eugen; Tchrakian, D H

    2011-02-18

    We construct finite mass, asymptotically flat black hole solutions in d=5 Einstein-Yang-Mills-Chern-Simons theory. Our results indicate the existence of a second order phase transition between Reissner-Nordström solutions and the non-Abelian black holes which generically are thermodynamically preferred. Some of the non-Abelian configurations are also stable under linear, spherically symmetric perturbations.

  15. Periodic solutions of the N-body problem

    CERN Document Server

    Meyer, Kenneth R

    1999-01-01

    The N-body problem is the classical prototype of a Hamiltonian system with a large symmetry group and many first integrals. These lecture notes are an introduction to the theory of periodic solutions of such Hamiltonian systems. From a generic point of view the N-body problem is highly degenerate. It is invariant under the symmetry group of Euclidean motions and admits linear momentum, angular momentum and energy as integrals. Therefore, the integrals and symmetries must be confronted head on, which leads to the definition of the reduced space where all the known integrals and symmetries have been eliminated. It is on the reduced space that one can hope for a nonsingular Jacobian without imposing extra symmetries. These lecture notes are intended for graduate students and researchers in mathematics or celestial mechanics with some knowledge of the theory of ODE or dynamical system theory. The first six chapters develops the theory of Hamiltonian systems, symplectic transformations and coordinates, periodic so...

  16. Asymptotically Almost Periodic Solutions for a Class of Stochastic Functional Differential Equations

    Directory of Open Access Journals (Sweden)

    Aimin Liu

    2014-01-01

    Full Text Available This work is concerned with the quadratic-mean asymptotically almost periodic mild solutions for a class of stochastic functional differential equations dxt=Atxt+Ft,xt,xtdt+H(t,xt,xt∘dW(t. A new criterion ensuring the existence and uniqueness of the quadratic-mean asymptotically almost periodic mild solutions for the system is presented. The condition of being uniformly exponentially stable of the strongly continuous semigroup {Tt}t≥0 is essentially removed, which is generated by the linear densely defined operator A∶D(A⊂L2(ℙ,ℍ→L2(ℙ,ℍ, only using the exponential trichotomy of the system, which reflects a deeper analysis of the behavior of solutions of the system. In this case the asymptotic behavior is described through the splitting of the main space into stable, unstable, and central subspaces at each point from the flow’s domain. An example is also given to illustrate our results.

  17. Absence of periodic orbits in digital memcomputing machines with solutions.

    Science.gov (United States)

    Di Ventra, Massimiliano; Traversa, Fabio L

    2017-10-01

    In Traversa and Di Ventra [Chaos 27, 023107 (2017)] we argued, without proof, that if the non-linear dynamical systems with memory describing the class of digital memcomputing machines (DMMs) have equilibrium points, then no periodic orbits can emerge. In fact, the proof of such a statement is a simple corollary of a theorem already demonstrated in Traversa and Di Ventra [Chaos 27, 023107 (2017)]. Here, we point out how to derive such a conclusion. Incidentally, the same demonstration implies absence of chaos, a result we have already demonstrated in Di Ventra and Traversa [Phys. Lett. A 381, 3255 (2017)] using topology. These results, together with those in Traversa and Di Ventra [Chaos 27, 023107 (2017)], guarantee that if the Boolean problem the DMMs are designed to solve has a solution, the system will always find it, irrespective of the initial conditions.

  18. Stability and uniqueness of slowly oscillating periodic solutions to Wright's equation

    Science.gov (United States)

    Jaquette, Jonathan; Lessard, Jean-Philippe; Mischaikow, Konstantin

    2017-12-01

    In this paper, we prove that Wright's equation y‧ (t) = - αy (t - 1) { 1 + y (t) } has a unique slowly oscillating periodic solution (SOPS) for all parameter values α ∈ [ 1.9 , 6.0 ], up to time translation. Our proof is based on the same strategy employed earlier by Xie [27]; show that every SOPS is asymptotically stable. We first introduce a branch and bound algorithm to control all SOPS using bounding functions at all parameter values α ∈ [ 1.9 , 6.0 ]. Once the bounding functions are constructed, we then control the Floquet multipliers of all possible SOPS by solving rigorously an eigenvalue problem, again using a formulation introduced by Xie. Using these two main steps, we prove that all SOPS of Wright's equation are asymptotically stable for α ∈ [ 1.9 , 6.0 ], and the proof follows. This result is a step toward the proof of the Jones' Conjecture formulated in 1962.

  19. Global exponential stability and existence of periodic solutions in BAM networks with delays and reaction-diffusion terms

    International Nuclear Information System (INIS)

    Song Qiankun; Cao Jinde

    2005-01-01

    Both exponential stability and periodic solutions are considered for a class of bi-directional associative memory (BAM) neural networks with delays and reaction-diffusion terms by constructing suitable Lyapunov functional and some analysis techniques. The general sufficient conditions are given ensuring the global exponential stability and existence of periodic solutions of BAM neural networks with delays and reaction-diffusion terms. These presented conditions are in terms of system parameters and have important leading significance in the design and applications of globally exponentially stable and periodic oscillatory neural circuits for BAM with delays and reaction-diffusion terms

  20. Solutions of the Strominger System via Stable Bundles on Calabi-Yau Threefolds

    DEFF Research Database (Denmark)

    Andreas, Björn; Garcia Fernandez, Mario

    2012-01-01

    We prove that a given Calabi-Yau threefold with a stable holomorphic vector bundle can be perturbed to a solution of the Strominger system provided that the second Chern class of the vector bundle is equal to the second Chern class of the tangent bundle. If the Calabi-Yau threefold has strict SU(...

  1. Stability of periodic steady-state solutions to a non-isentropic Euler-Poisson system

    Science.gov (United States)

    Liu, Cunming; Peng, Yue-Jun

    2017-06-01

    We study the stability of periodic smooth solutions near non-constant steady-states for a non-isentropic Euler-Poisson system without temperature damping term. The system arises in the theory of semiconductors for which the doping profile is a given smooth function. In this stability problem, there are no special restrictions on the size of the doping profile, but only on the size of the perturbation. We prove that small perturbations of periodic steady-states are exponentially stable for large time. For this purpose, we introduce new variables and choose a non-diagonal symmetrizer of the full Euler equations to recover dissipation estimates. This also allows to make the proof of the stability result very simple and concise.

  2. Polarons as stable solitary wave solutions to the Dirac-Coulomb system

    Science.gov (United States)

    Comech, Andrew; Zubkov, Mikhail

    2013-11-01

    We consider solitary wave solutions to the Dirac-Coulomb system both from physical and mathematical points of view. Fermions interacting with gravity in the Newtonian limit are described by the model of Dirac fermions with the Coulomb attraction. This model also appears in certain condensed matter systems with emergent Dirac fermions interacting via optical phonons. In this model, the classical soliton solutions of equations of motion describe the physical objects that may be called polarons, in analogy to the solutions of the Choquard equation. We develop analytical methods for the Dirac-Coulomb system, showing that the no-node gap solitons for sufficiently small values of charge are linearly (spectrally) stable.

  3. Periodic and solitary wave solutions of cubic–quintic nonlinear ...

    Indian Academy of Sciences (India)

    odic, double-kink, bell and antikink-type solutions for cubic–quintic nonlinear reaction-diffusion equation are extracted. Such solutions can be used to explain various biological and physical phenomena. Keywords. Variable coefficient reaction-diffusion equation; solitary wave solution; cubic–quintic nonlinearity. PACS No.

  4. Effect of Different Cultivation Periods on Soil Stable Organic Carbon Pool in Citrus Orchard

    Directory of Open Access Journals (Sweden)

    WANG Yi-xiang

    2015-08-01

    Full Text Available Effect of different cultivation periods on soil stable organic carbon pools and fractions in citrus orchard was investigated to provide scientific basis on the study of orchard soil carbon sequestration by the temporal-spatial substitution method and physical and chemical fractionation method. The results showed that the citrus orchard planted in 1954 compared with the citrus orchard planted in 1980, the content of total organic carbon increased by 27.16%, organic carbon content in macro-aggregates increased by 13.59%, organic carbon content in micro-aggregates increased by 80.19%, organic carbon content of heavy fraction increased by 29.25%, resistant organic carbon content increased by 32.00%, black carbon content increased by 4.01%. Organic carbon which combined with micro-aggregates was protected, and resistant organic carbon and black carbon were recalcitrant organic carbon in soil, this indicated that the stable organic carbon fractions gradually enriched in soil with the increase of growing periods, which was conducive to improve carbon sink in citrus orchard soil.

  5. Stability of the Simplest Periodic Solutions in the Stuart–Landau Equation with Large Delay

    Directory of Open Access Journals (Sweden)

    A. A. Kashchenko

    2012-01-01

    Full Text Available We study the local dynamics of the Stuart–Landau equation with large delay in the neibourhood of periodic solutions. We find sufficient conditions of instability of periodic solutions and sufficient conditions of their stability.

  6. Existence and multiplicity of periodic solutions generated by impulses for second-order Hamiltonian system

    Directory of Open Access Journals (Sweden)

    Dan Zhang

    2014-05-01

    Full Text Available In this article, we study the existence of non-zero periodic solutions for Hamiltonian systems with impulsive conditions. By using a variational method and a variant fountain theorem, we obtain new criteria to guarantee that the system has at least one non-zero periodic solution or infinitely many non-zero periodic solutions. However, without impulses, there is no non-zero periodic solution for the system under our conditions.

  7. The existence and global exponential stability of a periodic solution of a class of delay differential equations

    International Nuclear Information System (INIS)

    Tang, X H; Zou, Xingfu

    2009-01-01

    By employing Schauder's fixed point theorem and a non-Liapunov method (matrix theory, inequality analysis), we obtain some new criteria that ensure existence and global exponential stability of a periodic solution to a class of functional differential equations. Applying these criteria to a cellular neural network with time delays (delayed cellular neural network, DCNN) under a periodic environment leads to some new results that improve and generalize many existing ones we know on this topic. These results are of great significance in designs and applications of globally stable periodic DCNNs

  8. Modulation equations for spatially periodic systems: derivation and solutions

    NARCIS (Netherlands)

    Schielen, R.; Doelman, A.

    1996-01-01

    We study a class of partial dierential equations in one spatial dimension, which can be seen as model equations for the analysis of pattern formation in physical systems dened on unbounded, weakly oscillating domains. We perform a linear and weakly nonlinear stability analysis for solutions that

  9. Solitary wave and periodic wave solutions for Burgers, Fisher ...

    Indian Academy of Sciences (India)

    the travelling wave solutions plays an important role in nonlinear sciences. Many power- ful methods have been presented, including the inverse scattering transform [1], Hirota's bilinear method [2], homotopy analysis method [3–5], variational iteration method [6,7], homotopy perturbation method [8–10], Painlevé expansion ...

  10. Periodic and subharmonic solutions for second order p-Laplacian ...

    Indian Academy of Sciences (India)

    [15] Jiang D, Chu J, O'regan D and Agarwal R P, Positive solutions for continuous and dis- crete boundary value problems to the one-dimension p-Laplacian, Math. Inequal. Appl. 7 (2004) 523–534. [16] Kocic V L and Ladas G, Global Behavior of Nonlinear Difference Equations of High. Order with Applications (Boston: ...

  11. Periodic pulse solutions to slowly nonlinear reaction-diffusion systems

    NARCIS (Netherlands)

    Rijk, de B.

    2016-01-01

    The presence of a small parameter can reduce the complexity of the stability analysis of pattern solutions. This reduction manifests itself through the complex-analytic Evans function, which vanishes on the spectrum of the linearization about the pattern. For certain 'slowly linear' prototype models

  12. Classification of stable solutions for non-homogeneous higher-order elliptic PDEs

    Directory of Open Access Journals (Sweden)

    Abdellaziz Harrabi

    2017-04-01

    Full Text Available Abstract Under some assumptions on the nonlinearity f, we will study the nonexistence of nontrivial stable solutions or solutions which are stable outside a compact set of R n $\\mathbb {R}^{n}$ for the following semilinear higher-order problem: ( − Δ k u = f ( u in  R n , $$\\begin{aligned} (-\\Delta^{k} u= f(u \\quad \\mbox{in }\\mathbb {R}^{n}, \\end{aligned}$$ with k = 1 , 2 , 3 , 4 $k=1,2,3,4$ . The main methods used are the integral estimates and the Pohozaev identity. Many classes of nonlinearity will be considered; even the sign-changing nonlinearity, which has an adequate subcritical growth at zero as for example f ( u = − m u + λ | u | θ − 1 u − μ | u | p − 1 u $f(u= -m u +\\lambda|u|^{\\theta-1}u-\\mu |u|^{p-1}u$ , where m ≥ 0 $m\\geq0$ , λ > 0 $\\lambda>0$ , μ > 0 $\\mu>0$ , p , θ > 1 $p, \\theta>1$ . More precisely, we shall revise the nonexistence theorem of Berestycki and Lions (Arch. Ration. Mech. Anal. 82:313-345, 1983 in the class of smooth finite Morse index solutions as the well known work of Bahri and Lions (Commun. Pure Appl. Math. 45:1205-1215, 1992. Also, the case when f ( u u $f(uu$ is a nonnegative function will be studied under a large subcritical growth assumption at zero, for example f ( u = | u | θ − 1 u ( 1 + | u | q $f(u=|u|^{\\theta-1}u(1 + |u|^{q}$ or f ( u = | u | θ − 1 u e | u | q $f(u= |u|^{\\theta-1}u e^{|u|^{q}}$ , θ > 1 $\\theta>1$ and q > 0 $q>0$ . Extensions to solutions which are merely stable are discussed in the case of supercritical growth with k = 1 $k=1$ .

  13. Staggered and short-period solutions of the saturable discrete nonlinear Schrodinger equation

    DEFF Research Database (Denmark)

    Khare, A.; Rasmussen, K.O.; Samuelsen, Mogens Rugholm

    2009-01-01

    We point out that the nonlinear Schrodinger lattice with a saturable nonlinearity also admits staggered periodic aswell as localized pulse-like solutions. Further, the same model also admits solutions with a short period. We examine the stability of these solutions and find that the staggered...

  14. Early visual ERPs show stable body-sensitive patterns over a 4-week test period

    Science.gov (United States)

    Groves, Katie; Kennett, Steffan; Gillmeister, Helge

    2018-01-01

    Event-related potential (ERP) studies feature among the most cited papers in the field of body representation, with recent research highlighting the potential of ERPs as neuropsychiatric biomarkers. Despite this, investigation into how reliable early visual ERPs and body-sensitive effects are over time has been overlooked. This study therefore aimed to assess the stability of early body-sensitive effects and visual P1, N1 and VPP responses. Participants were asked to identify pictures of their own bodies, other bodies and houses during an EEG test session that was completed at the same time, once a week, for four consecutive weeks. Results showed that amplitude and latency of early visual components and their associated body-sensitive effects were stable over the 4-week period. Furthermore, correlational analyses revealed that VPP component amplitude might be more reliable than VPP latency and specific electrode sites might be more robust indicators of body-sensitive cortical activity than others. These findings suggest that visual P1, N1 and VPP responses, alongside body-sensitive N1/VPP effects, are robust indications of neuronal activity. We conclude that these components are eligible to be considered as electrophysiological biomarkers relevant to body representation. PMID:29438399

  15. Stable reconstruction of Arctic sea level for the 1950-2010 period

    DEFF Research Database (Denmark)

    Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg

    2016-01-01

    Reconstruction of historical Arctic sea level is generally difficult due to the limited coverage and quality of both tide gauge and altimetry data in the area. Here a strategy to achieve a stable and plausible reconstruction of Arctic sea level from 1950 to today is presented. This work is based......, a datum-fit of each tide gauges is used and the method takes into account the entirety of each tide gauge record. This makes the Arctic sea level reconstruction much less prone to drifting.From our reconstruction, we found that the Arctic mean sea level trend is around 1.5 mm +/- 0.3 mm/y for the period...... on the combination of tide gauge records and a new 20-year reprocessed satellite altimetry derived sea level pattern. Hence the study is limited to the area covered by satellite altimetry (68ºN and 82ºN). It is found that timestep cumulative reconstruction as suggested by Church and White (2000) may yield widely...

  16. Existence and stability of periodic solutions for a delayed prey-predator model with diffusion effects

    Directory of Open Access Journals (Sweden)

    Hongwei Liang

    2016-01-01

    Full Text Available Existence and stability of spatially periodic solutions for a delay prey-predator diffusion system are concerned in this work. We obtain that the system can generate the spatially nonhomogeneous periodic solutions when the diffusive rates are suitably small. This result demonstrates that the diffusion plays an important role on deriving the complex spatiotemporal dynamics. Meanwhile, the stability of the spatially periodic solutions is also studied. Finally, in order to verify our theoretical results, some numerical simulations are also included.

  17. Periodic solution and stationary distribution of stochastic SIR epidemic models with higher order perturbation

    Science.gov (United States)

    Liu, Qun; Jiang, Daqing; Hayat, Tasawar; Ahmad, Bashir

    2017-09-01

    In this paper, we investigate two stochastic SIR epidemic models with higher order perturbation. For the nonautonomous periodic case of the model, by using Has'minskii's theory of periodic solution, we show that the system has at least one nontrivial positive T-periodic solution. For the system disturbed by both the white noise and telephone noise, we establish sufficient conditions for positive recurrence and the existence of ergodic stationary distribution of the positive solution.

  18. Stable branches of a solution for a fermion on domain wall

    Energy Technology Data Exchange (ETDEWEB)

    Gani, V. A. [National Research Nuclear University MEPhI, Department of Mathematics (Russian Federation); Ksenzov, V. G.; Kudryavtsev, A. E. [Institute for Theoretical and Experimental Physics (Russian Federation)

    2011-05-15

    The case when a fermion occupies an excited nonzero frequency level in the field of domain wall is discussed. It is demonstrated that a solution exists for the coupling constant in the limited interval 1 < g < g{sub max} Almost-Equal-To 1.65. It is shown that indeed there are different branches of stable solution for g in this interval. The first one corresponds to a fermion located on the domain wall (1 < g < 4{radical}2{pi}). The second branch, which belongs to the interval 4{radical}2{pi} {<=} g {<=} g{sub max}, describes a polarized fermion off the domain wall. The third branch with 1 < g < g{sub max} describes an excited antifermion in the field of the domain wall.

  19. Ground state solutions for asymptotically periodic Schrodinger equations with critical growth

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    2013-10-01

    Full Text Available Using the Nehari manifold and the concentration compactness principle, we study the existence of ground state solutions for asymptotically periodic Schrodinger equations with critical growth.

  20. Almost Periodic Solution for Memristive Neural Networks with Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Huaiqin Wu

    2013-01-01

    Full Text Available This paper is concerned with the dynamical stability analysis for almost periodic solution of memristive neural networks with time-varying delays. Under the framework of Filippov solutions, by applying the inequality analysis techniques, the existence and asymptotically almost periodic behavior of solutions are discussed. Based on the differential inclusions theory and Lyapunov functional approach, the stability issues of almost periodic solution are investigated, and a sufficient condition for the existence, uniqueness, and global exponential stability of the almost periodic solution is established. Moreover, as a special case, the condition which ensures the global exponential stability of a unique periodic solution is also presented for the considered memristive neural networks. Two examples are given to illustrate the validity of the theoretical results.

  1. Solute dispersion for stable density-driven flow in randomly heterogeneous porous media

    Science.gov (United States)

    Dell'Oca, Aronne; Riva, Monica; Carrera, Jesus; Guadagnini, Alberto

    2018-01-01

    We present a theoretical investigation on the processes underpinning the reduced longitudinal spreading documented in stable variable density flows, as opposed to constant density settings, within heterogeneous porous media. We do so by decomposing velocity and pressure in terms of stationary and dynamic components. The former corresponds to the solution of the constant density flow problem, while the latter accounts for the effects induced by density variability. We focus on a stable flow configuration and analyze the longitudinal spread of saltwater injected from the bottom of a column formed by a heterogeneous porous medium initially fully saturated by freshwater. We adopt a perturbation expansion approach and derive the equations satisfied by section-averaged concentrations and their ensemble mean values. These formulations are respectively characterized by a single realization and an ensemble dispersive flux, which we determine through appropriate closure equations. The latter are solved via semi-analytical and numerical approaches. Our formulations and associated results enable us to discriminate the relative impact on the density-driven solute displacement of (a) covariance of the permeability of the porous medium, (b) cross-covariance between permeability and concentration, which is in turn linked to the coupling of flow and transport problems, and (c) cross-covariance between the dynamic and stationary velocities.

  2. Asymptotically Stable Solutions of a Generalized Fractional Quadratic Functional-Integral Equation of Erdélyi-Kober Type

    Directory of Open Access Journals (Sweden)

    Mohamed Abdalla Darwish

    2014-01-01

    Full Text Available We study a generalized fractional quadratic functional-integral equation of Erdélyi-Kober type in the Banach space BC(ℝ+. We show that this equation has at least one asymptotically stable solution.

  3. Asymptotically Stable Solutions of a Generalized Fractional Quadratic Functional-Integral Equation of Erdélyi-Kober Type

    OpenAIRE

    Darwish, Mohamed Abdalla; Rzepka, Beata

    2014-01-01

    We study a generalized fractional quadratic functional-integral equation of Erdélyi-Kober type in the Banach space BC(ℝ+). We show that this equation has at least one asymptotically stable solution.

  4. Existence and stability of almost periodic solutions to differential equations with piecewise constant arguments

    Directory of Open Access Journals (Sweden)

    Samuel Castillo

    2015-03-01

    Full Text Available This work concerns the existence of almost periodic solutions for certain differential equations with piecewise constant arguments. The coefficients of these equations are almost periodic and the equation can be seen as perturbations of a linear equation satisfying an exponential dichotomy on a difference equation. The stability of that solution on a semi-axis is also studied.

  5. New results of almost periodic solutions for cellular neural networks with mixed delays

    International Nuclear Information System (INIS)

    Zhao Weirui; Zhang Huanshui

    2009-01-01

    In this paper, for cellular neural networks with mixed delays, we prove some new results on the existence of almost periodic solutions by contraction principle. The global exponential stability of almost periodic solutions is discussed further, and conditions for exponential convergence are given. The conditions we obtained are weaker than the previously known ones and can be easily reduced to several special cases.

  6. Global stability and existence of periodic solutions of discrete delayed cellular neural networks

    International Nuclear Information System (INIS)

    Li Yongkun

    2004-01-01

    We use the continuation theorem of coincidence degree theory and Lyapunov functions to study the existence and stability of periodic solutions for the discrete cellular neural networks (CNNs) with delays xi(n+1)=xi(n)e-bi(n)h+θi(h)-bar j=1maij(n)fj(xj(n))+θi(h)-bar j=1mbij(n)fj(xj(n- τij(n)))+θi(h)Ii(n),i=1,2,...,m. We obtain some sufficient conditions to ensure that for the networks there exists a unique periodic solution, and all its solutions converge to such a periodic solution

  7. A class of doubly periodic wave solutions for the generalized Nizhnik-Novikov-Veselov equation

    International Nuclear Information System (INIS)

    Peng Yanze

    2005-01-01

    A general solution including two arbitrary functions is first obtained for the generalized Nizhnik-Novikov-Veselov equation by means of WTC truncation method. A class of doubly periodic wave solutions, which are expressed as rational functions of the Jacobi elliptic functions with different moduli, result from the general solution. Limit cases are considered and some new solitary structures are revealed. The interaction properties of periodic waves are numerically studied and found to be nonelastic. Under long wave limit, a two-dromion solution with the new solution structure is obtained and interaction between the two dromions is completely elastic

  8. Identification of Parameters through the Approximate Periodic Solutions of a Parabolic System

    OpenAIRE

    Lei, Ling

    2006-01-01

    This work is concerned with the identification problem for what we call the perturbation term or error term in a parabolic partial differential equation, through its approximate periodic solutions. The observation is made over a subregion of the physical domain. The existence and uniqueness problem of the approximate periodic solutions is studied in the first part of the paper. A solution to the identification problem is given in the second part of the paper. The main ingredients to be used i...

  9. Stability and periodicity of solutions for delay dynamic systems on time scales

    Directory of Open Access Journals (Sweden)

    Zhi-Qiang Zhu

    2014-04-01

    Full Text Available This article concerns the stability and periodicity of solutions to the delay dynamic system $$ x^{\\triangle}(t=A(t x(t + F(t, x(t, x(g(t+C(t $$ on a time scale. By the inequality technique for vectors, we obtain some stability criteria for the above system. Then, by using the Horn fixed point theorem, we present some conditions under which our system is asymptotically periodic and its periodic solution is unique. In particular, the periodic solution is positive under proper assumptions.

  10. Stabilization of periodic solutions in a tethered satellite system by damping injection

    DEFF Research Database (Denmark)

    Larsen, Martin Birkelund; Blanke, Mogens

    2009-01-01

    A spacecraft with electrodynamic tether orbiting the Earth will be subject to a periodic forcing term induced by the variation of the magnetic field along the orbit. The periodic forcing term leads to a family of unstable periodic solutions for a tether carrying a constant current. This paper...... to affect the orbit parameters. An approximation of the periodic solutions of the closed loop system is found as a series expansion in the parameter plane spanned by the controller gain and the bias term. The stability of the solutions is investigated using linear Floquet analysis of the variational...

  11. A potential new, stable state of the E-cadherin strand-swapped dimer in solution.

    Science.gov (United States)

    Schumann-Gillett, Alexandra; Mark, Alan E; Deplazes, Evelyne; O'Mara, Megan L

    2018-01-01

    E-cadherin is a transmembrane glycoprotein that facilitates inter-cellular adhesion in the epithelium. The ectodomain of the native structure is comprised of five repeated immunoglobulin-like domains. All E-cadherin crystal structures show the protein in one of three alternative conformations: a monomer, a strand-swapped trans homodimer and the so-called X-dimer, which is proposed to be a kinetic intermediate to forming the strand-swapped trans homodimer. However, previous studies have indicated that even once the trans strand-swapped dimer is formed, the complex is highly dynamic and the E-cadherin monomers may reorient relative to each other. Here, molecular dynamics simulations have been used to investigate the stability and conformational flexibility of the human E-cadherin trans strand-swapped dimer. In four independent, 100 ns simulations, the dimer moved away from the starting structure and converged to a previously unreported structure, which we call the Y-dimer. The Y-dimer was present for over 90% of the combined simulation time, suggesting that it represents a stable conformation of the E-cadherin dimer in solution. The Y-dimer conformation is stabilised by interactions present in both the trans strand-swapped dimer and X-dimer crystal structures, as well as additional interactions not found in any E-cadherin dimer crystal structures. The Y-dimer represents a previously unreported, stable conformation of the human E-cadherin trans strand-swapped dimer and suggests that the available crystal structures do not fully capture the conformations that the human E-cadherin trans homodimer adopts in solution.

  12. The Rational Solutions and Quasi-Periodic Wave Solutions as well as Interactions of N-Soliton Solutions for 3 + 1 Dimensional Jimbo-Miwa Equation

    Directory of Open Access Journals (Sweden)

    Hongwei Yang

    2016-01-01

    Full Text Available The exact rational solutions, quasi-periodic wave solutions, and N-soliton solutions of 3 + 1 dimensional Jimbo-Miwa equation are acquired, respectively, by using the Hirota method, whereafter the rational solutions are also called algebraic solitary waves solutions and used to describe the squall lines phenomenon and explained possible formation mechanism of the rainstorm formation which occur in the atmosphere, so the study on the rational solutions of soliton equations has potential application value in the atmosphere field; the soliton fission and fusion are described based on the resonant solution which is a special form of the N-soliton solutions. At last, the interactions of the solitons are shown with the aid of N-soliton solutions.

  13. Stable, metastable and unstable solutions of a spin-1 Ising system based on the free energy surfaces

    Science.gov (United States)

    Keskİin, Mustafa; Özgan, Şükrü

    1990-04-01

    Stable, metastable and unstable solutions of a spin-1 Ising model with bilinear and biquadratic interactions are found by using the free energy surfaces. The free energy expression is obtained in the lowest approximation of the cluster variation method. All these solutions are shown in the two-dimensional phase space, especially the unstable solutions which in some cases are difficult to illustrate in the two-dimensional phase space, found by Keskin et al. recently.

  14. Application of stable, nitroxide free radicals in solution to low magnetic fields measurements

    International Nuclear Information System (INIS)

    Besson, Rene

    1973-01-01

    The first attempts to use the Overhauser-Abragam effect for measuring low magnetic fields date back to 1956. However, the instability of the free radical used, PREMY'S Salt, as well as its virtual insolubility in solvents other than water, hampered the development of the nuclear magnetic resonance magnetometer realized in accordance to this principle: dynamic polarization of protons. New free radicals stable and soluble in many solvents, will enhanced the interest in the device. In particular, the use of 2,2,6,6, tetramethyl- piperidine-4-one-1-oxide (TANO or TANONE) leads to a high sensitivity, low field magnetometer. The methods of measurements, the required apparatus and sample preparation are first described. Next the results of measurements made both in high and low magnetic fields with various free radicals in different solvents are presented in tabular and graphical form. These measurements have determined which radical-solvent couple will yield a high dynamic polarization coefficient. In addition, the improvement obtained by complete deuteration of the free radical has been demonstrated. Problems connected with the application of such radicals in solution to the 'double effect probe' of the magnetometer built by LETI at CEN Grenoble and the solutions reached are discussed. (author) [fr

  15. Stable algorithm for the computation of the electromagnetic field distribution of eigenmodes of periodic diffraction structures.

    Science.gov (United States)

    Bezus, Evgeni A; Doskolovich, Leonid L

    2012-11-01

    In the present work, a stable algorithm for the calculation of the electromagnetic field distributions of the eigenmodes of one-dimensional diffraction gratings is presented. The proposed approach is based on the method for the computation of the propagation constants of Bloch waves of such structures previously presented by Cao et al.[J. Opt. Soc. Am. A 19, 335 (2002)] and uses a modified S-matrix algorithm to ensure numerical stability.

  16. A stable numerical solution method in-plane loading of nonlinear viscoelastic laminated orthotropic materials

    Science.gov (United States)

    Gramoll, K. C.; Dillard, D. A.; Brinson, H. F.

    1989-01-01

    In response to the tremendous growth in the development of advanced materials, such as fiber-reinforced plastic (FRP) composite materials, a new numerical method is developed to analyze and predict the time-dependent properties of these materials. Basic concepts in viscoelasticity, laminated composites, and previous viscoelastic numerical methods are presented. A stable numerical method, called the nonlinear differential equation method (NDEM), is developed to calculate the in-plane stresses and strains over any time period for a general laminate constructed from nonlinear viscoelastic orthotropic plies. The method is implemented in an in-plane stress analysis computer program, called VCAP, to demonstrate its usefulness and to verify its accuracy. A number of actual experimental test results performed on Kevlar/epoxy composite laminates are compared to predictions calculated from the numerical method.

  17. Existence of infinitely many periodic solutions for second-order nonautonomous Hamiltonian systems

    Directory of Open Access Journals (Sweden)

    Wen Guan

    2015-04-01

    Full Text Available By using minimax methods and critical point theory, we obtain infinitely many periodic solutions for a second-order nonautonomous Hamiltonian systems, when the gradient of potential energy does not exceed linear growth.

  18. Positive Almost Periodic Solutions for a Time-Varying Fishing Model with Delay

    Directory of Open Access Journals (Sweden)

    Xia Li

    2011-01-01

    Full Text Available This paper is concerned with a time-varying fishing model with delay. By means of the continuation theorem of coincidence degree theory, we prove that it has at least one positive almost periodic solution.

  19. Globally exponential stability and periodic solutions of CNNS with variable coefficients and variable delays

    International Nuclear Information System (INIS)

    Liu Haifei; Wang Li

    2006-01-01

    In this Letter, by using the inequality method and the Lyapunov functional method, we analyze the globally exponential stability and the existence of periodic solutions of a class of cellular neutral networks with delays and variable coefficients. Some simple and new sufficient conditions ensuring the existence and uniqueness of globally exponential stability of periodic solutions for cellular neutral networks with variable coefficients and delays are obtained. In addition, one example is also worked out to illustrate our theory

  20. Globally exponential stability and periodic solutions of CNNS with variable coefficients and variable delays

    Energy Technology Data Exchange (ETDEWEB)

    Liu Haifei [School of Management and Engineering, Nanjing University, Nanjing 210093 (China)]. E-mail: hfliu80@126.com; Wang Li [School of Management and Engineering, Nanjing University, Nanjing 210093 (China)

    2006-09-15

    In this Letter, by using the inequality method and the Lyapunov functional method, we analyze the globally exponential stability and the existence of periodic solutions of a class of cellular neutral networks with delays and variable coefficients. Some simple and new sufficient conditions ensuring the existence and uniqueness of globally exponential stability of periodic solutions for cellular neutral networks with variable coefficients and delays are obtained. In addition, one example is also worked out to illustrate our theory.

  1. MULTIPLE STABLE PERIODIC SOLUTIONS IN A MODEL FOR THE HORMONAL REGULATION OF THE MENSTRUAL CYCLE

    Science.gov (United States)

    ABSTRACTThe pituitary hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and the ovarian hormones, estradiol (E2), progesterone (P4), and inhibin (Ih), are five hormones important for the regulation and maintenance of the human menstrual cycle. The...

  2. The role of periodic solutions in the Falkner-Skan problem for λ > 0

    NARCIS (Netherlands)

    Botta, E.F.T.; Hut, F.J.; Veldman, A.E.P.

    1986-01-01

    The Falkner-Skan equation f '" + ff" + λ(1 - f'^2) = 0 is discussed for λ > 0. Two types of solutions have been pursued: those satisfying f(0) = f'(0) = 0, f'(∞) = 1 and those being periodic. In both cases, numerical evidence is given for a rich structure of multiple solutions. Branching occurs for

  3. Periodic solutions to singular second order differential equations: the repulsive case

    Czech Academy of Sciences Publication Activity Database

    Hakl, Robert; Torres, P.J.; Zamora, M.

    2012-01-01

    Roč. 39, č. 2 (2012), s. 199-220 ISSN 1230-3429 Institutional support: RVO:67985840 Keywords : singular nonlinear boundary value problem * positive solutions * periodic solutions Subject RIV: BA - General Mathematics Impact factor: 1.099, year: 2012

  4. Existence of Solutions of Periodic Boundary Value Problems for Impulsive Functional Duffing Equations at Nonresonance Case

    Directory of Open Access Journals (Sweden)

    Liu Yuji

    2008-01-01

    Full Text Available Abstract This paper deals with the existence of solutions of the periodic boundary value problem of the impulsive Duffing equations: . Sufficient conditions are established for the existence of at least one solution of above-mentioned boundary value problem. Our method is based upon Schaeffer's fixed-point theorem. Examples are presented to illustrate the efficiency of the obtained results.

  5. New Exact Travelling Wave and Periodic Solutions of Discrete Nonlinear Schroedinger Equation

    International Nuclear Information System (INIS)

    Yang Qin; Dai Chaoqing; Zhang Jiefang

    2005-01-01

    Some new exact travelling wave and period solutions of discrete nonlinear Schroedinger equation are found by using a hyperbolic tangent function approach, which was usually presented to find exact travelling wave solutions of certain nonlinear partial differential models. Now we can further extend the new algorithm to other nonlinear differential-different models.

  6. On exact solutions of the regularized long-wave equation: A direct approach to partially integrable equations. II. Periodic solutions

    Science.gov (United States)

    Parker, A.

    1995-07-01

    In this second of two articles (designated I and II), the bilinear transformation method is used to obtain stationary periodic solutions of the partially integrable regularized long-wave (RLW) equation. These solutions are expressed in terms of Riemann theta functions, and this approach leads to a new and compact expression for the important dispersion relation. The periodic solution (or cnoidal wave) can be represented as an infinite sum of sech2 ``solitary waves'': this remarkable property may be interpreted in the context of a nonlinear superposition principle. The RLW cnoidal wave approximates to a sinusoidal wave and a solitary wave in the limits of small and large amplitudes, respectively. Analytic approximations and error estimates are given which shed light on the character of the cnoidal wave in the different parameter regimes. Similar results are presented in brief for the related RLW Boussinesq (RLWB) equation.

  7. Stabilization of periodic solutions in a tethered satellite system by damping injection

    DEFF Research Database (Denmark)

    Larsen, Martin Birkelund; Blanke, Mogens

    2009-01-01

    presents a control design for stabilizing these periodic solutions. The design consists of a control law for stabilizing the open-loop equilibrium and a bias term which forces the system trajectory away from the equilibrium. The tether needs to be positioned away from open-loop equilibrium for the tether...... to affect the orbit parameters. An approximation of the periodic solutions of the closed loop system is found as a series expansion in the parameter plane spanned by the controller gain and the bias term. The stability of the solutions is investigated using linear Floquet analysis of the variational...

  8. New binary travelling-wave periodic solutions for the modified KdV equation

    International Nuclear Information System (INIS)

    Yan Zhenya

    2008-01-01

    In this Letter, the modified Korteweg-de Vries (mKdV) equations with the focusing (+) and defocusing (-) branches are investigated, respectively. Many new types of binary travelling-wave periodic solutions are obtained for the mKdV equation in terms of Jacobi elliptic functions such as sn(ξ,m)cn(ξ,m)dn(ξ,m) and their extensions. Moreover, we analyze asymptotic properties of some solutions. In addition, with the aid of the Miura transformation, we also give the corresponding binary travelling-wave periodic solutions of KdV equation

  9. Symmetric periodic solutions for a class of differential delay equations with distributed delay

    Directory of Open Access Journals (Sweden)

    Benjamin Kennedy

    2014-03-01

    where $g$ and $f$ are smooth, bounded, and odd and satisfy a positive and a negative feedback condition, respectively. Using elementary fixed point theory we prove the existence of a nontrivial periodic solution of period $2 + 2d$ satisfying certain symmetries, given certain growth conditions on $f$ and $g$ near zero.

  10. Periodic solutions for impulsive delay differential equations in the control model of plankton allelopathy

    Energy Technology Data Exchange (ETDEWEB)

    Jia Junguo [Department of Applied Mathematics, Xi' an Jiaotong University, Xi' an 710049 (China) and Department of Mathematics, Zhengzhou University, Zhengzhou, Henan 450001 (China)]. E-mail: jungjia2@zzu.edu.cn; Wang Miansen [Department of Applied Mathematics, Xi' an Jiaotong University, Xi' an 710049 (China); Li Meili [Department of Applied Mathematics, Xi' an Jiaotong University, Xi' an 710049 (China)

    2007-05-15

    In this paper, a two-dimensional non-autonomous system with impulse that arises in plankton allelopathy involving discrete time delays and periodic environmental factors is studied. By the theory of the coincidence degree we obtain the conditions for the existence of periodic solution of this system.

  11. On stable exponential cosmological solutions with non-static volume factor in the Einstein-Gauss-Bonnet model

    International Nuclear Information System (INIS)

    Ivashchuk, V D; Ernazarov, K K

    2017-01-01

    A ( n + 1)-dimensional gravitational model with cosmological constant and Gauss-Bonnet term is studied. The ansatz with diagonal cosmological metrics is adopted and solutions with exponential dependence of scale factors: a i ∼ exp ( v i t ), i = 1, …, n , are considered. The stability analysis of the solutions with non-static volume factor is presented. We show that the solutions with v 1 = v 2 = v 3 = H > 0 and small enough variation of the effective gravitational constant G are stable if certain restriction on ( v i ) is obeyed. New examples of stable exponential solutions with zero variation of G in dimensions D = 1 + m + 2 with m > 2 are presented. (paper)

  12. Multi-stability and almost periodic solutions of a class of recurrent neural networks

    International Nuclear Information System (INIS)

    Liu Yiguang; You Zhisheng

    2007-01-01

    This paper studies multi-stability, existence of almost periodic solutions of a class of recurrent neural networks with bounded activation functions. After introducing a sufficient condition insuring multi-stability, many criteria guaranteeing existence of almost periodic solutions are derived using Mawhin's coincidence degree theory. All the criteria are constructed without assuming the activation functions are smooth, monotonic or Lipschitz continuous, and that the networks contains periodic variables (such as periodic coefficients, periodic inputs or periodic activation functions), so all criteria can be easily extended to fit many concrete forms of neural networks such as Hopfield neural networks, or cellular neural networks, etc. Finally, all kinds of simulations are employed to illustrate the criteria

  13. Periodic Solutions of Duffing Equation with an Asymmetric Nonlinearity and a Deviating Argument

    Directory of Open Access Journals (Sweden)

    Zaihong Wang

    2013-01-01

    Full Text Available We study the existence of periodic solutions of the second-order differential equation x′′+ax+-bx-+g(x(t-τ=p(t, where a,b are two constants satisfying 1/a+1/b=2/n, n∈N, τ is a constant satisfying 0≤τ<2π, g,p:R→R are continuous, and p is 2π-periodic. When the limits limx→±∞g(x=g(±∞ exist and are finite, we give some sufficient conditions for the existence of 2π-periodic solutions of the given equation.

  14. Stable monopole and dyon solutions in the einstein-yang-mills theory in asymptotically anti-de sitter space

    Science.gov (United States)

    Bjoraker; Hosotani

    2000-02-28

    A continuum of new monopole and dyon solutions in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter space are found. They are regular everywhere and specified by their mass and their non-Abelian electric and magnetic charges. A class of monopole solutions which have no node in non-Abelian magnetic fields is shown to be stable against spherically symmetric linear perturbations.

  15. Existence of pseudo almost periodic solutions for a class of partial functional differential equations

    Directory of Open Access Journals (Sweden)

    Hui-Sheng Ding

    2013-04-01

    Full Text Available In this paper, we first introduce a new class of pseudo almost periodic type functions and investigate some properties of pseudo almost periodic type functions; and then we discuss the existence of pseudo almost periodic solutions to the class of abstract partial functional differential equations $x'(t=Ax(t+f(t,x_t$ with finite delay in a Banach space X.

  16. Existence and stability of periodic solution in impulsive Hopfield neural networks with finite distributed delays

    International Nuclear Information System (INIS)

    Yang Xiaofan; Liao Xiaofeng; Evans, David J.; Tang Yuanyan

    2005-01-01

    In this Letter, we introduce a class of Hopfield neural networks with periodic impulses and finite distributed delays. We then derive a sufficient condition for the existence and global exponential stability of a unique periodic solution of the networks, which assumes neither the differentiability nor the monotonicity of the activation functions. Our condition extends and generalizes a known condition for the global exponential periodicity of continuous Hopfield neural networks with finite distributed delays

  17. Stretchable Spin Valve with Stable Magnetic Field Sensitivity by Ribbon-Patterned Periodic Wrinkles.

    Science.gov (United States)

    Li, Huihui; Zhan, Qingfeng; Liu, Yiwei; Liu, Luping; Yang, Huali; Zuo, Zhenghu; Shang, Tian; Wang, Baomin; Li, Run-Wei

    2016-04-26

    A strain-relief structure by combining the strain-engineered periodic wrinkles and the parallel ribbons was employed to fabricate flexible dual spin valves onto PDMS substrates in a direct sputtering method. The strain-relief structure can accommodate the biaxial strain accompanying with stretching operation (the uniaxial applied tensile strain and the induced transverse compressive strain due to the Poisson effect), thus significantly reducing the influence of the residual strain on the giant magnetoresistance (GMR) performance. The fabricated GMR dual spin-valve sensor exhibits the nearly unchanged MR ratio of 9.9%, magnetic field sensitivity up to 0.69%/Oe, and zero-field resistance in a wide range of stretching strain, making it promising for applications on a conformal shape or a movement part.

  18. Solutions to fourth-order random differential equations with periodic boundary conditions

    Directory of Open Access Journals (Sweden)

    Xiaoling Han

    2012-12-01

    Full Text Available Existence of solutions and of extremal random solutions are proved for periodic boundary-value problems of fourth-order ordinary random differential equations. Our investigation is done in the space of continuous real-valued functions defined on closed and bounded intervals. Also we study the applications of the random version of a nonlinear alternative of Leray-Schauder type and an algebraic random fixed point theorem by Dhage.

  19. A stable and robust calibration scheme of the log-periodic power law model

    Science.gov (United States)

    Filimonov, V.; Sornette, D.

    2013-09-01

    We present a simple transformation of the formulation of the log-periodic power law formula of the Johansen-Ledoit-Sornette (JLS) model of financial bubbles that reduces it to a function of only three nonlinear parameters. The transformation significantly decreases the complexity of the fitting procedure and improves its stability tremendously because the modified cost function is now characterized by good smooth properties with in general a single minimum in the case where the model is appropriate to the empirical data. We complement the approach with an additional subordination procedure that slaves two of the nonlinear parameters to the most crucial nonlinear parameter, the critical time tc, defined in the JLS model as the end of the bubble and the most probable time for a crash to occur. This further decreases the complexity of the search and provides an intuitive representation of the results of the calibration. With our proposed methodology, metaheuristic searches are not longer necessary and one can resort solely to rigorous controlled local search algorithms, leading to a dramatic increase in efficiency. Empirical tests on the Shanghai Composite index (SSE) from January 2007 to March 2008 illustrate our findings.

  20. Stable dipole solitons and soliton complexes in the nonlinear Schrödinger equation with periodically modulated nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, M. E., E-mail: gloriouslair@gmail.com, E-mail: galfimov@yahoo.com; Alfimov, G. L., E-mail: gloriouslair@gmail.com, E-mail: galfimov@yahoo.com [National Research University of Electronic Technology MIET, Zelenograd, Moscow 124498 (Russian Federation); Malomed, Boris A., E-mail: malomed@post.tau.ac.il [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel); Laboratory of Nonlinear-Optical Informatics, ITMO University, St. Petersburg 197101 (Russian Federation)

    2016-07-15

    We develop a general classification of the infinite number of families of solitons and soliton complexes in the one-dimensional Gross-Pitaevskii/nonlinear Schrödinger equation with a nonlinear lattice pseudopotential, i.e., periodically modulated coefficient in front of the cubic term, which takes both positive and negative local values. This model finds direct implementations in atomic Bose-Einstein condensates and nonlinear optics. The most essential finding is the existence of two branches of dipole solitons (DSs), which feature an antisymmetric shape, being essentially squeezed into a single cell of the nonlinear lattice. This soliton species was not previously considered in nonlinear lattices. We demonstrate that one branch of the DS family (namely, which obeys the Vakhitov-Kolokolov criterion) is stable, while unstable DSs spontaneously transform into stable fundamental solitons (FSs). The results are obtained in numerical and approximate analytical forms, the latter based on the variational approximation. Some stable bound states of FSs are found too.

  1. Periodic Solutions, Eigenvalue Curves, and Degeneracy of the Fractional Mathieu Equation

    Science.gov (United States)

    Parra-Hinojosa, A.; Gutiérrez-Vega, J. C.

    2016-03-01

    We investigate the eigenvalue curves, the behavior of the periodic solutions, and the orthogonality properties of the Mathieu equation with an additional fractional derivative term using the method of harmonic balance. The addition of the fractional derivative term breaks the hermiticity of the equation in such a way that its eigenvalues need not be real nor its eigenfunctions orthogonal. We show that for a certain choice of parameters the eigenvalue curves reveal the appearance of degenerate eigenvalues. We offer a detailed discussion of the matrix representation of the differential operator corresponding to the fractional Mathieu equation, as well as some numerical examples of its periodic solutions.

  2. Periodic Solutions, Eigenvalue Curves, and Degeneracy of the Fractional Mathieu Equation

    International Nuclear Information System (INIS)

    Parra-Hinojosa, A; Gutiérrez-Vega, J C

    2016-01-01

    We investigate the eigenvalue curves, the behavior of the periodic solutions, and the orthogonality properties of the Mathieu equation with an additional fractional derivative term using the method of harmonic balance. The addition of the fractional derivative term breaks the hermiticity of the equation in such a way that its eigenvalues need not be real nor its eigenfunctions orthogonal. We show that for a certain choice of parameters the eigenvalue curves reveal the appearance of degenerate eigenvalues. We offer a detailed discussion of the matrix representation of the differential operator corresponding to the fractional Mathieu equation, as well as some numerical examples of its periodic solutions. (paper)

  3. Variational Approaches for the Existence of Multiple Periodic Solutions of Differential Delay Equations

    Directory of Open Access Journals (Sweden)

    Rong Cheng

    2010-01-01

    Full Text Available The existence of multiple periodic solutions of the following differential delay equation (=−((− is established by applying variational approaches directly, where ∈ℝ, ∈(ℝ,ℝ and >0 is a given constant. This means that we do not need to use Kaplan and Yorke's reduction technique to reduce the existence problem of the above equation to an existence problem for a related coupled system. Such a reduction method introduced first by Kaplan and Yorke in (1974 is often employed in previous papers to study the existence of periodic solutions for the above equation and its similar ones by variational approaches.

  4. Analytical Structuring of Periodic and Regular Cascading Solutions in Self-Pulsing Lasers

    Directory of Open Access Journals (Sweden)

    Belkacem Meziane

    2008-01-01

    Full Text Available A newly proposed strong harmonic-expansion method is applied to the laser-Lorenz equations to analytically construct a few typical solutions, including the first few expansions of the well-known period-doubling cascade that characterizes the system in its self-pulsing regime of operation. These solutions are shown to evolve in accordance with the driving frequency of the permanent solution that we recently reported to illustrate the system. The procedure amounts to analytically construct the signal Fourier transform by applying an iterative algorithm that reconstitutes the first few terms of its development.

  5. The Kuramoto–Sivashinsky equation. A Local Attractor Filled with Unstable Periodic Solutions

    Directory of Open Access Journals (Sweden)

    Anatoli N. Kulikov

    2018-01-01

    Full Text Available A periodic boundary value problem is considered for one version of the KuramotoSivashinsky equation, which is widely known in mathematical physics. Local bifurcations in a neighborhood of the spatially homogeneous equilibrium points in the case when they change stability are studied. It is shown that the loss of stability of homogeneous equilibrium points leads to the appearance of a two-dimensional attractor on which all solutions are periodic functions of time, except one spatially inhomogeneous state. A spectrum of frequencies of the given family of periodic solutions fills the entire number line, and they are all unstable in a sense of Lyapunov definition in the metric of the phase space (space of initial conditions of the corresponding initial boundary value problem. It is chosen the Sobolev space as the phase space. For the periodic solutions which fill the two-dimensional attractor, the asymptotic formulas are given. In order to analyze the bifurcation problem it was used analysis methods for infinite-dimensional dynamical systems: the integral (invariant manifold method, the Poincare normal form theory, and asymptotic methods. The analysis of bifurcations for periodic boundary value problem was reduced to analysing the structure of the neighborhood of the zero solution of the homogeneous Dirichlet boundary value problem for the considered equation. 

  6. Bifurcation phenomena and attractive periodic solutions in the saturating inductor circuit

    CERN Document Server

    Bartuccelli, M V; Gentile, G

    2006-01-01

    In this paper we investigate bifurcation phenomena, such as those of the periodic solutions, for the ``unperturbed'' nonlinear system $G(\\dot{x}) \\ddot{x} + \\beta x =0$, with $G(\\dot{x}) = (\\alpha + \\dot{x}^2)/(1+\\dot{x}^2)$ and $\\alpha > 1$, $\\beta > 0$, when we add the two competing terms $-f(t) + \\gamma \\dot{x}$, with $f(t)$ a time-periodic analytic ``forcing'' function and $\\gamma>0$ the dissipative parameter. The resulting differential equation $G(\\dot{x}) \\ddot{x} + \\beta x + \\gamma \\dot{x} - f(t) = 0$ describes approximately an electronic system known as the saturating inductor circuit. For any periodic orbit of the unperturbed system we provide conditions which give rise to the appearance of subharmonic solutions. Furthermore we show that other bifurcation phenomena arise, as there is a periodic solution with the same period as the forcing function $f(t)$ which branches off the origin when the perturbation is switched on. We also show that such a solution, which encircles the origin, attracts the enti...

  7. The effect of temperature on generic stable periodic structures in the parameter space of dissipative relativistic standard map

    Science.gov (United States)

    Horstmann, Ana C. C.; Albuquerque, Holokx A.; Manchein, Cesar

    2017-05-01

    In this work, we have characterized changes in the dynamics of a two-dimensional relativistic standard map in the presence of dissipation and specially when it is submitted to thermal effects modeled by a Gaussian noise reservoir. By the addition of thermal noise in the dissipative relativistic standard map (DRSM) it is possible to suppress typical stable periodic structures (SPSs) embedded in the chaotic domains of parameter space for large enough temperature strengths. Smaller SPSs are first affected by thermal effects, starting from their borders, as a function of temperature. To estimate the necessary temperature strength capable to destroy those SPSs we use the largest Lyapunov exponent to obtain the critical temperature (TC) diagrams. For critical temperatures the chaotic behavior takes place with the suppression of periodic motion, although the temperature strengths considered in this work are not so large to convert the deterministic features of the underlying system into a stochastic ones.

  8. Global Classical Solutions of Three Dimensional Viscous MHD System Without Magnetic Diffusion on Periodic Boxes

    Science.gov (United States)

    Pan, Ronghua; Zhou, Yi; Zhu, Yi

    2018-02-01

    In this paper, we study the global existence of classical solutions to the three dimensional incompressible viscous magneto-hydrodynamical system without magnetic diffusion on periodic boxes, that is, with periodic boundary conditions. We work in Eulerian coordinates and employ a time-weighted energy estimate to prove the global existence result, under the assumptions that the initial magnetic field is close enough to an equilibrium state and the initial data have some symmetries.

  9. Observations and light curve solutions of four ultrashort-period binaries

    Directory of Open Access Journals (Sweden)

    Kjurkchieva D.

    2016-01-01

    Full Text Available The paper presents light curve solutions of our observations of four new ultrashort-period eclipsing binaries with MS components. Two of them have periods almost at the upper limit (0.22 days of the ultrashort-period binaries, while the periods of around 0.18 days of CSS J171508.5+350658 and CSS J214633.8+120016 are amongst the shortest known orbital periods. CSS J171410.0+ 445850, CSS J214633.8+120016 and CSS J224326.0+154532 are over contact binaries with fill out factors around 0.25 while CSS J171508.5+350658 is a semidetached system. The two targets with shortest periods consist of M dwarfs.

  10. Component-wise positivity of solutions to periodic boundary problem for linear functional differential system

    Czech Academy of Sciences Publication Activity Database

    Domoshnitsky, A.; Hakl, Robert; Šremr, Jiří

    2012-01-01

    Roč. 112, May 22 (2012), s. 1-23 ISSN 1025-5834 Institutional support: RVO:67985840 Keywords : periodic problem * linear functional differential system * non- negative solution Subject RIV: BA - General Mathematics Impact factor: 0.879, year: 2010 http://www.journalofinequalitiesandapplications.com/content/2012/1/112

  11. Existence of Infinitely Many Periodic Solutions for Perturbed Semilinear Fourth-Order Impulsive Differential Inclusions

    Directory of Open Access Journals (Sweden)

    Massimiliano Ferrara

    2016-01-01

    Full Text Available This paper discusses the existence of infinitely many periodic solutions for a semilinear fourth-order impulsive differential inclusion with a perturbed nonlinearity and two parameters. The approach is based on a critical point theorem for nonsmooth functionals.

  12. Generalized Asymptotically Almost Periodic and Generalized Asymptotically Almost Automorphic Solutions of Abstract Multiterm Fractional Differential Inclusions

    Directory of Open Access Journals (Sweden)

    G. M. N’Guérékata

    2018-01-01

    Full Text Available The main aim of this paper is to investigate generalized asymptotical almost periodicity and generalized asymptotical almost automorphy of solutions to a class of abstract (semilinear multiterm fractional differential inclusions with Caputo derivatives. We illustrate our abstract results with several examples and possible applications.

  13. Periodic solutions of an indefinite singular equation arising from the Kepler problem on the sphere

    Czech Academy of Sciences Publication Activity Database

    Hakl, Robert; Zamora, M.

    2018-01-01

    Roč. 70, č. 1 (2018), s. 173-190 ISSN 0008-414X Institutional support: RVO:67985840 Keywords : indefinite singularity * periodic solution * Kepler problem on S^1 Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 0.963, year: 2016 https://cms.math.ca/10.4153/CJM-2016-050-1

  14. Existence and uniqueness of a periodic solution to an indefinite attractive singular equation

    Czech Academy of Sciences Publication Activity Database

    Hakl, Robert; Zamora, M.

    2016-01-01

    Roč. 195, č. 3 (2016), s. 995-1009 ISSN 0373-3114 Institutional support: RVO:67985840 Keywords : singular differential equation * periodic solution * uniqueness Subject RIV: BA - General Mathematics Impact factor: 0.864, year: 2016 http://link.springer.com/article/10.1007%2Fs10231-015-0501-3

  15. Anti-periodic solutions for recurrent neural networks without assuming global Lipschitz conditions

    Directory of Open Access Journals (Sweden)

    Hong Zhang

    2010-04-01

    Full Text Available In this paper we study recurrent neural networks with time-varying delays and continuously distributed delays. Without assuming global Lipschitz conditions on the activation functions, we establish the existence and local exponential stability of anti-periodic solutions.

  16. Multiple Positive Periodic Solutions for Functional Differential Equations with Impulses and a Parameter

    Directory of Open Access Journals (Sweden)

    Zhenguo Luo

    2014-01-01

    Full Text Available We apply the Krasnoselskii fixed-point theorem to investigate the existence of multiple positive periodic solutions for a class of impulsive functional differential equations with a parameter; some verifiable sufficient results are established easily. In particular, our results extend and improve some previous results.

  17. Existence of periodic solutions for Rayleigh equations with state-dependent delay

    Directory of Open Access Journals (Sweden)

    Jehad O. Alzabut

    2012-05-01

    Full Text Available We establish sufficient conditions for the existence of periodic solutions for a Rayleigh-type equation with state-dependent delay. Our approach is based on the continuation theorem in degree theory, and some analysis techniques. An example illustrates that our approach to this problem is new.

  18. Periodic solution of a stochastic SIRS epidemic model with seasonal variation.

    Science.gov (United States)

    Jin, Manli; Lin, Yuguo

    2018-12-01

    In this paper, we consider a stochastic SIRS epidemic model with seasonal variation and saturated incidence. Firstly, we obtain the threshold of stochastic system which determines whether the epidemic occurs or not. Secondly, we prove that there is a non-trivial positive periodic solution if [Formula: see text].

  19. Periodic solutions to the Liénard type equations with phase attractive singularities

    Czech Academy of Sciences Publication Activity Database

    Hakl, Robert; Zamora, M.

    -, 6 March (2013), s. 47 ISSN 1687-2770 Institutional support: RVO:67985840 Keywords : Rayleigh-Plesset equation * singular equation * periodic solution Subject RIV: BA - General Mathematics Impact factor: 0.836, year: 2013 http://www.boundaryvalueproblems.com/content/2013/1/47

  20. Four positive periodic solutions of a discrete time Lotka-Volterra competitive system with harvesting terms

    Directory of Open Access Journals (Sweden)

    Xinggui Liu

    2011-01-01

    Full Text Available In this paper, by using Mawhin's continuation theorem of coincidence degree theory, we establish the existence of at least four positive periodic solutions for a discrete time Lotka-Volterra competitive system with harvesting terms. An example is given to illustrate the effectiveness of our results.

  1. Existence and global exponential stability of periodic solution of CNNs with impulses

    Energy Technology Data Exchange (ETDEWEB)

    Li Yongkun [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China); Xing Zhiwei [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China)

    2007-08-15

    Sufficient conditions are obtained for the existence and global exponential stability of a unique periodic solution of cellular neural networks with variable time delays and impulses by using Mawhin's continuation theorem of coincidence degree and by means of a method based on delay differential inequality.

  2. Existence and global exponential stability of periodic solution of CNNs with impulses

    International Nuclear Information System (INIS)

    Li Yongkun; Xing Zhiwei

    2007-01-01

    Sufficient conditions are obtained for the existence and global exponential stability of a unique periodic solution of cellular neural networks with variable time delays and impulses by using Mawhin's continuation theorem of coincidence degree and by means of a method based on delay differential inequality

  3. Periodic solutions of first-order functional differential equations in population dynamics

    CERN Document Server

    Padhi, Seshadev; Srinivasu, P D N

    2014-01-01

    This book provides cutting-edge results on the existence of multiple positive periodic solutions of first-order functional differential equations. It demonstrates how the Leggett-Williams fixed-point theorem can be applied to study the existence of two or three positive periodic solutions of functional differential equations with real-world applications, particularly with regard to the Lasota-Wazewska model, the Hematopoiesis model, the Nicholsons Blowflies model, and some models with Allee effects. Many interesting sufficient conditions are given for the dynamics that include nonlinear characteristics exhibited by population models. The last chapter provides results related to the global appeal of solutions to the models considered in the earlier chapters. The techniques used in this book can be easily understood by anyone with a basic knowledge of analysis. This book offers a valuable reference guide for students and researchers in the field of differential equations with applications to biology, ecology, a...

  4. Existence of Positive Periodic Solutions for n-Dimensional Nonautonomous System

    Directory of Open Access Journals (Sweden)

    Youjun Liu

    2014-01-01

    Full Text Available In this paper we consider the existence, multiplicity, and nonexistence of positive periodic solutions for n-dimensional nonautonomous functional differential system x'(t=H(t,x(t-λB(tF(x(t-τ(t, where hi are ω-periodic in t and there exist ω-periodic functions αi,βi∈C(R,R+ such that αi(t≤(hi(t,x/xi≤βi(t,∫0ω‍αi(tdt>0, for x∈R+n all with xi>0, and t∈R, limxi→0+(hi(t,x/xi exist for t∈R; bi∈C(R,R+ are ω-periodic functions and ∫0ω‍bi(tdt>0;fi∈C(R+n,R+, fi(x>0 for x >0; τ∈(R,R is an ω-periodic function. We show that the system has multiple or no positive ω-periodic solutions for sufficiently large or small λ>0, respectively.

  5. Organic solution-processible electroluminescent molecular glasses for non-doped standard red OLEDs with electrically stable chromaticity

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Xiaoman; Zuo, Weiwei; Liu, Yingliang, E-mail: liuylxn@sohu.com; Zhang, Zhenru; Zeng, Cen; Xu, Shengang; Cao, Shaokui, E-mail: caoshaokui@zzu.edu.cn

    2015-10-15

    Highlights: • The D–A–D electroluminescent molecular glasses are synthesized. • Non-doped red electroluminescent film is fabricated by spin-coating. • Red OLED shows stable wavelength, luminous efficiency and chromaticity. • CIE1931 coordinate is in accord with standard red light in PAL system. - Abstract: Organic light-emitting molecular glasses (OEMGs) are synthesized through the introduction of nonplanar donor and branched aliphatic chain into electroluminescent emitters. The target OEMGs are characterized by {sup 1}H NMR, {sup 13}C NMR, IR, UV–vis and fluorescent spectra as well as elemental analysis, TG and DSC. The results indicated that the optical, electrochemical and electroluminescent properties of OEMGs are adjusted successfully by the replacement of electron-donating group. The non-doped OLED device with a standard red electroluminescent emission is achieved by spin-coating the THF solution of OEMG with a triphenylamine moiety. This non-doped red OLED device takes on an electrically stable electroluminescent performance, including the stable maximum electroluminescent wavelength of 640 nm, the stable luminous efficiency of 2.4 cd/A and the stable CIE1931 coordinate of (x, y) = (0.64, 0.35), which is basically in accord with the CIE1931 coordinate (x, y) = (0.64, 0.33) of standard red light in PAL system.

  6. Accurate analytical periodic solution of the elliptical Kepler equation using the Adomian decomposition method

    Science.gov (United States)

    Alshaery, Aisha; Ebaid, Abdelhalim

    2017-11-01

    Kepler's equation is one of the fundamental equations in orbital mechanics. It is a transcendental equation in terms of the eccentric anomaly of a planet which orbits the Sun. Determining the position of a planet in its orbit around the Sun at a given time depends upon the solution of Kepler's equation, which we will solve in this paper by the Adomian decomposition method (ADM). Several properties of the periodicity of the obtained approximate solutions have been proved in lemmas. Our calculations demonstrated a rapid convergence of the obtained approximate solutions which are displayed in tables and graphs. Also, it has been shown in this paper that only a few terms of the Adomian decomposition series are sufficient to achieve highly accurate numerical results for any number of revolutions of the Earth around the Sun as a consequence of the periodicity property. Numerically, the four-term approximate solution coincides with the Bessel-Fourier series solution in the literature up to seven decimal places at some values of the time parameter and nine decimal places at other values. Moreover, the absolute error approaches zero using the nine term approximate Adomian solution. In addition, the approximate Adomian solutions for the eccentric anomaly have been used to show the convergence of the approximate radial distances of the Earth from the Sun for any number of revolutions. The minimal distance (perihelion) and maximal distance (aphelion) approach 147 million kilometers and 152.505 million kilometers, respectively, and these coincide with the well known results in astronomical physics. Therefore, the Adomian decomposition method is validated as an effective tool to solve Kepler's equation for elliptical orbits.

  7. Periodic travelling and non-travelling wave solutions of the nonlinear Klein-Gordon equation with imaginary mass

    International Nuclear Information System (INIS)

    Tang Xiaoyan; Shukla, Padma Kant

    2008-01-01

    Exact solutions, including the periodic travelling and non-travelling wave solutions, are presented for the nonlinear Klein-Gordon equation with imaginary mass. Some arbitrary functions are permitted in the periodic non-travelling wave solutions, which contribute to various high dimensional nonlinear structures

  8. The multi-order envelope periodic solutions to the nonlinear Schrodinger equation and cubic nonlinear Schrodinger equation

    International Nuclear Information System (INIS)

    Xiao Yafeng; Xue Haili; Zhang Hongqing

    2011-01-01

    Based on Jacobi elliptic function and the Lame equation, the perturbation method is applied to get the multi-order envelope periodic solutions of the nonlinear Schrodinger equation and cubic nonlinear Schrodinger equation. These multi-order envelope periodic solutions can degenerate into the different envelope solitary solutions. (authors)

  9. Stable preparations of tyrosine hydroxylase provide the solution structure of the full-length enzyme

    Science.gov (United States)

    Bezem, Maria T.; Baumann, Anne; Skjærven, Lars; Meyer, Romain; Kursula, Petri; Martinez, Aurora; Flydal, Marte I.

    2016-01-01

    Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of catecholamine neurotransmitters. TH is a highly complex enzyme at mechanistic, structural, and regulatory levels, and the preparation of kinetically and conformationally stable enzyme for structural characterization has been challenging. Here, we report on improved protocols for purification of recombinant human TH isoform 1 (TH1), which provide large amounts of pure, stable, active TH1 with an intact N-terminus. TH1 purified through fusion with a His-tagged maltose-binding protein on amylose resin was representative of the iron-bound functional enzyme, showing high activity and stabilization by the natural feedback inhibitor dopamine. TH1 purified through fusion with a His-tagged ZZ domain on TALON is remarkably stable, as it was partially inhibited by resin-derived cobalt. This more stable enzyme preparation provided high-quality small-angle X-ray scattering (SAXS) data and reliable structural models of full-length tetrameric TH1. The SAXS-derived model reveals an elongated conformation (Dmax = 20 nm) for TH1, different arrangement of the catalytic domains compared with the crystal structure of truncated forms, and an N-terminal region with an unstructured tail that hosts the phosphorylation sites and a separated Ala-rich helical motif that may have a role in regulation of TH by interacting with binding partners. PMID:27462005

  10. Global stability, periodic solutions, and optimal control in a nonlinear differential delay model

    Directory of Open Access Journals (Sweden)

    Anatoli F. Ivanov

    2010-09-01

    Full Text Available A nonlinear differential equation with delay serving as a mathematical model of several applied problems is considered. Sufficient conditions for the global asymptotic stability and for the existence of periodic solutions are given. Two particular applications are treated in detail. The first one is a blood cell production model by Mackey, for which new periodicity criteria are derived. The second application is a modified economic model with delay due to Ramsey. An optimization problem for a maximal consumption is stated and solved for the latter.

  11. Periodic Solution of Second-Order Hamiltonian Systems with a Change Sign Potential on Time Scales

    Directory of Open Access Journals (Sweden)

    You-Hui Su

    2009-01-01

    Full Text Available This paper is concerned with the second-order Hamiltonian system on time scales 𝕋 of the form uΔΔ(ρ(t+μb(t|u(t|μ−2u(t+∇¯H(t,u(t=0, Δ-a.e. t∈[0,T]𝕋 , u(0−u(T=uΔ(ρ(0−uΔ(ρ(T=0, where 0,T∈𝕋. By using the minimax methods in critical theory, an existence theorem of periodic solution for the above system is established. As an application, an example is given to illustrate the result. This is probably the first time the existence of periodic solutions for second-order Hamiltonian system on time scales has been studied by critical theory.

  12. Periodic solution for state-dependent impulsive shunting inhibitory CNNs with time-varying delays.

    Science.gov (United States)

    Şaylı, Mustafa; Yılmaz, Enes

    2015-08-01

    In this paper, we consider existence and global exponential stability of periodic solution for state-dependent impulsive shunting inhibitory cellular neural networks with time-varying delays. By means of B-equivalence method, we reduce these state-dependent impulsive neural networks system to an equivalent fix time impulsive neural networks system. Further, by using Mawhin's continuation theorem of coincide degree theory and employing a suitable Lyapunov function some new sufficient conditions for existence and global exponential stability of periodic solution are obtained. Previous results are improved and extended. Finally, we give an illustrative example with numerical simulations to demonstrate the effectiveness of our theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Periodic Solutions for Duffing Type p-Laplacian Equation with Multiple Constant Delays

    Directory of Open Access Journals (Sweden)

    Hong Zhang

    2012-01-01

    Full Text Available Using inequality techniques and coincidence degree theory, new results are provided concerning the existence and uniqueness of periodic solutions for the Duffing type p-Laplacian equation with multiple constant delays of the form (φp(x′(t′+Cx′(t+g0(t,x(t+∑k=1ngk(t,x(t-τk=e(t. Moreover, an example is provided to illustrate the effectiveness of the results in this paper.

  14. Global exponential stability of periodic solution for shunting inhibitory CNNs with delays [rapid communication

    Science.gov (United States)

    Li, Yongkun; Liu, Chunchao; Zhu, Lifei

    2005-03-01

    By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, we study the existence and stability of periodic solution for shunting inhibitory cellular neural networks (SICNNs) with delays x˙ij(t)=-aij(t)xij(t)-∑Bkl∈Nr(i,j)Bijkl(t)fij(xkl(t))xij(t)-∑Ckl∈Nr(i,j)Cijkl(t)gij(xkl(t-τkl))xij(t)+Lij(t).

  15. Stable Covalent Organic Frameworks for Exceptional Mercury Removal from Aqueous Solutions.

    Science.gov (United States)

    Huang, Ning; Zhai, Lipeng; Xu, Hong; Jiang, Donglin

    2017-02-15

    The pre-designable porous structures found in covalent organic frameworks (COFs) render them attractive as a molecular platform for addressing environmental issues such as removal of toxic heavy metal ions from water. However, a rational structural design of COFs in this aspect has not been explored. Here we report the rational design of stable COFs for Hg(II) removal through elaborate structural design and control over skeleton, pore size, and pore walls. The resulting framework is stable under strong acid and base conditions, possesses high surface area, has large mesopores, and contains dense sulfide functional termini on the pore walls. These structural features work together in removing Hg(II) from water and achieve a benchmark system that combines capacity, efficiency, effectivity, applicability, selectivity, and reusability. These results suggest that COFs offer a powerful platform for tailor-made structural design to cope with various types of pollution.

  16. Unencapsulated Air-stable Organic Field Effect Transistor by All Solution Processes for Low Power Vapor Sensing

    Science.gov (United States)

    Feng, Linrun; Tang, Wei; Zhao, Jiaqing; Yang, Ruozhang; Hu, Wei; Li, Qiaofeng; Wang, Ruolin; Guo, Xiaojun

    2016-02-01

    With its excellent mechanical flexibility, low-cost and low-temperature processing, the solution processed organic field-effect transistor (OFET) is a promising platform technology for developing ubiquitous sensor applications in digital health, environment monitoring and Internet of Things. However, a contradiction between achieving low voltage operation and having stable performance severely hinder the technology to become commercially viable. This work shows that, by reducing the sub-gap density of states (DOS) at the channel for low operation voltage and using a proper low-k non-polar polymer dielectric layer, such an issue can be addressed. Stable electrical properties after either being placed for weeks or continuously prolonged bias stressing for hours in ambient air are achieved for all solution processed unencapsulated OFETs with the channel being exposed to the ambient air for analyte detection. The fabricated device presents a steep subthreshold swing less than 100 mV/decade, and an ON/OFF ratio of 106 at a voltage swing of 3 V. The low voltage and stable operation allows the sensor made of the OFET to be incorporated into a battery-powered electronic system for continuously reliable sensing of ammonia vapor in ambient air with very small power consumption of about 50 nW.

  17. Classification of solutions of the forced periodic nonlinear Schrödinger equation

    International Nuclear Information System (INIS)

    Shlizerman, Eli; Rom-Kedar, Vered

    2010-01-01

    The integrable structure of the periodic one-dimensional nonlinear Schrödinger equation is utilized to gain insights regarding the perturbed near-integrable dynamics. After recalling the known results regarding the structure and stability of the unperturbed standing and travelling waves solutions, two new stability results are presented: (1) it is shown numerically that the stability of the 'outer' (cnoidal) unperturbed solutions depends on their power (the L 2 norm): they undergo a finite sequence of Hamiltonian–Hopf bifurcations as their power is increased. (2) another proof that the 'inner'(dnoidal) unperturbed solutions with multiplicity ≥2 are linearly unstable is presented. Then, to study the global phase-space structure, an energy–momentum bifurcation diagram (PDE-EMBD) that consists of projections of the unperturbed standing and travelling waves solutions to the energy–power plane and includes information regarding their linear stability is constructed. The PDE-EMBD helps us to classify the behaviour near the plane wave solutions: the diagram demonstrates that below some known threshold amplitude, precisely three distinct observable chaotic mechanisms arise: homoclinic chaos, homoclinic resonance and, for some parameter values, parabolic-resonance. Moreover, it appears that the dynamics of the PDE chaotic solutions that exhibit the parabolic-resonance instability may be qualitatively predicted: these exhibit the same dynamics as a recently derived parabolic-resonance low-dimensional normal form. In particular, these solutions undergo adiabatic chaos: they follow the level lines of an adiabatic invariant till they reach the separatrix set at which the adiabatic invariant undergoes essentially random jumps

  18. Classification of solutions of the forced periodic nonlinear Schrödinger equation

    Science.gov (United States)

    Shlizerman, Eli; Rom-Kedar, Vered

    2010-09-01

    The integrable structure of the periodic one-dimensional nonlinear Schrödinger equation is utilized to gain insights regarding the perturbed near-integrable dynamics. After recalling the known results regarding the structure and stability of the unperturbed standing and travelling waves solutions, two new stability results are presented: (1) it is shown numerically that the stability of the 'outer' (cnoidal) unperturbed solutions depends on their power (the L2 norm): they undergo a finite sequence of Hamiltonian-Hopf bifurcations as their power is increased. (2) another proof that the 'inner'(dnoidal) unperturbed solutions with multiplicity >=2 are linearly unstable is presented. Then, to study the global phase-space structure, an energy-momentum bifurcation diagram (PDE-EMBD) that consists of projections of the unperturbed standing and travelling waves solutions to the energy-power plane and includes information regarding their linear stability is constructed. The PDE-EMBD helps us to classify the behaviour near the plane wave solutions: the diagram demonstrates that below some known threshold amplitude, precisely three distinct observable chaotic mechanisms arise: homoclinic chaos, homoclinic resonance and, for some parameter values, parabolic-resonance. Moreover, it appears that the dynamics of the PDE chaotic solutions that exhibit the parabolic-resonance instability may be qualitatively predicted: these exhibit the same dynamics as a recently derived parabolic-resonance low-dimensional normal form. In particular, these solutions undergo adiabatic chaos: they follow the level lines of an adiabatic invariant till they reach the separatrix set at which the adiabatic invariant undergoes essentially random jumps.

  19. Gemini surfactant for fluorescent and stable quantum dots in aqueous solution

    International Nuclear Information System (INIS)

    Li Haibing; Wang Xiaoqiong; Gao Zhinong; He Zhike

    2007-01-01

    Highly fluorescent and stable CdSe/ZnS core/shell quantum dots (QDs) coated with gemini surfactant are successfully synthesized in aqueous media. Analyses of luminescence spectrometry, ultraviolet-visible (UV-vis) spectrophotometry, and transmission electron micrographs (TEMs) indicate that the water-soluble QDs are monodisperse and have a luminescence enhancement compared with the original hydrophobic QDs. The water-soluble QDs coated with gemini surfactant are shown to be biocompatible, photostable, and have been proven to be suitable for live cell imaging

  20. Doubly periodic wave and folded solitary wave solutions for (2 + 1)-dimensional higher-order Broer-Kaup equation

    International Nuclear Information System (INIS)

    Huang Wenhua; Liu Yulu; Lu Zhiming

    2007-01-01

    A general solution including three arbitrary functions is obtained for the (2 + 1)-dimensional high-order Broer-Kaup equation by means of WTC truncation method. From the general solution, doubly periodic wave solutions in terms of the Jacobian elliptic functions with different modulus and folded solitary wave solutions determined by appropriate multiple valued functions are obtained. Some interesting novel features and interaction properties of these exact solutions and coherent localized structures are revealed

  1. All-solution processed polymer light-emitting diodes with air stable metal-oxide electrodes

    NARCIS (Netherlands)

    Bruyn, P. de; Moet, D.J.D.; Blom, P.W.M.

    2012-01-01

    We present an all-solution processed polymer light-emitting diode (PLED) using spincoated zinc oxide (ZnO) and vanadium pentoxide (V2O5) as electron and hole injecting contact, respectively. We compare the performance of these devices to the standard PLED design using PEDOT:PSS as anode and Ba/Al as

  2. All-solution processed polymer light-emitting diodes with air stable metal-oxide electrodes

    NARCIS (Netherlands)

    de Bruyn, P.; Moet, D. J. D.; Blom, P. W. M.

    We present an all-solution processed polymer light-emitting diode (PLED) using spincoated zinc oxide (ZnO) and vanadium pentoxide (V2O5) as electron and hole injecting contact, respectively. We compare the performance of these devices to the standard PLED design using PEDOT:PSS as anode and Ba/Al as

  3. Stable Isotope Analyses of water and Aqueous Solutions by Conventional Dual-inlet Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Horita, Juske [ORNL; Kendall, C. [U.S. Geological Survey, Menlo Park, CA

    2004-01-01

    The foundation of various analytical methods for the stable isotope composition of water and other aqueous samples (natural abundance, {sup 1}H : {sup 2}H (D) = 99.985 : 0.015 atom%, and {sup 16}O : {sup 17}O : {sup 18}O = 99.762 : 0.038 : 0.200 atom%) was established during the Manhatten Project in the U.S.A., when large amounts of heavy water were produced for nuclear reactors (see Kirshenbaum, 1951, for a detailed account). From early on, there was great interest in the oxygen and hydrogen isotopic compositions of water, because they are the ideal tracers of water sources and reactions. The increased analytical precisions made possible by the subsequent development of modern gas-source isotope-ratio mass spectrometers with dual-inlets and multi-collectors, have caused the proliferation of new analytical methods and applications for the oxygen and hydrogen isotopic compositions of water. These stable isotopes have found wide applications in basic as well as applied sciences (chemistry, geology, hydrology, biology, medical sciences, and food sciences). This is because water is ubiquitous, is an essential and predominant ingredient of living organisms, and is perhaps the most reactive compound in the Earth.

  4. Investigating economic specialization on the central Peruvian coast: A reconstruction of Late Intermediate Period Ychsma diet using stable isotopes.

    Science.gov (United States)

    Marsteller, Sara J; Zolotova, Natalya; Knudson, Kelly J

    2017-02-01

    Hypothetical models of socioeconomic organization in pre-Columbian societies generated from the rich ethnohistoric record in the New World require testing against the archaeological and bioarchaeological record. Here, we test ethnohistorian Maria Rostworowski's horizontality model of socioeconomic specialization for the Central Andean coast by reconstructing dietary practices in the Late Intermediate Period (c. AD 900-1470) Ychsma polity to evaluate complexities in social behaviors prior to Inka imperial influence. Stable carbon and nitrogen isotope analysis of archaeological human bone collagen and apatite (δ 13 C col[VPDB], δ 15 N col[AIR] , δ 13 C ap[VPDB] ) and locally available foods is used to reconstruct the diets of individuals from Armatambo (n = 67), associated ethnohistorically with fishing, and Rinconada Alta (n = 46), associated ethnohistorically with agriculture. Overall, mean δ 15 N col[AIR] is significantly greater at Armatambo, while mean δ 13 C col[VPDB] and mean δ 13 C ap[VPDB] are not significantly different between the two sites. Within large-scale trends, adult mean δ 13 C ap[VPDB] is significantly greater at Armatambo. In addition, nearly one-third of Armatambo adults and adolescents show divergent δ 15 N col[AIR] values. These results indicate greater reliance on marine resources at Armatambo versus Rinconada Alta, supporting the ethnohistoric model of socioeconomic specialization for the Central Andean coast. Deviations from large-scale dietary trends suggest complexities not accounted for by the ethnohistoric model, including intra-community subsistence specialization and/or variation in resource access. © 2016 Wiley Periodicals, Inc.

  5. Fully stable cosmological solutions with a non-singular classical bounce

    Science.gov (United States)

    Ijjas, Anna; Steinhardt, Paul J.

    2017-01-01

    We recently showed how it is possible to use a cubic Galileon action to construct classical cosmological solutions that enter a contracting null energy condition (NEC) violating phase, bounce at finite values of the scale factor and exit into an expanding NEC-satisfying phase without encountering any singularities or pathologies. A drawback of these examples is that singular behavior is encountered at some time either just before or just after the NEC-violating phase. In this Letter, we show that it is possible to circumvent this problem by extending our method to actions that include the next order L4 Galileon interaction. Using this approach, we construct non-singular classical bouncing cosmological solutions that are non-pathological for all times.

  6. Solitary, explosive and periodic solutions for electron acoustic solitary waves with non-thermal hot ions

    Science.gov (United States)

    Elwakil, S. A.; Abulwafa, E. M.; El-Shewy, E. K.; Abd-El-Hamid, H. M.

    2011-11-01

    A theoretical investigation has been made for electron acoustic waves propagating in a system of unmagnetized collisionless plasma consists of a cold electron fluid and ions with two different temperatures in which the hot ions obey the non-thermal distribution. The reductive perturbation method has been employed to derive the Korteweg-de Vries equation for small but finite amplitude electrostatic waves. It is found that the presence of the energetic population of non-thermal hot ions δ, initial normalized equilibrium density of low temperature ions μ and the ratio of temperatures of low temperature ions to high temperature ions β do not only significantly modify the basic properties of solitary structure, but also change the polarity of the solitary profiles. At the critical hot ions density, the KdV equation is not appropriate for describing the system. Hence, a new set of stretched coordinates is considered to derive the modified KdV equation. In the vicinity of the critical hot ions density, neither KdV nor modified KdV equation is appropriate for describing the electron acoustic waves. Therefore, a further modified KdV equation is derived. An algebraic method with computerized symbolic computation, which greatly exceeds the applicability of the existing tanh, extended tanh methods in obtaining a series of exact solutions of the various KdV-type equations, is used here. Numerical studies have been reveals different solutions e.g., bell-shaped solitary pulses, singular solitary "blowup" solutions, Jacobi elliptic doubly periodic wave, Weierstrass elliptic doubly periodic type solutions, in addition to explosive pulses. The results of the present investigation may be applicable to some plasma environments, such as Earth's magnetotail region.

  7. The Iterative Solution to Discrete-Time H∞ Control Problems for Periodic Systems

    Directory of Open Access Journals (Sweden)

    Ivan G. Ivanov

    2016-03-01

    Full Text Available This paper addresses the problem of solving discrete-time H ∞ control problems for periodic systems. The approach for solving such a type of equations is well known in the literature. However, the focus of our research is set on the numerical computation of the stabilizing solution. In particular, two effective methods for practical realization of the known iterative processes are described. Furthermore, a new iterative approach is investigated and applied. On the basis of numerical experiments, we compare the presented methods. A major conclusion is that the new iterative approach is faster than rest of the methods and it uses less RAM memory than other methods.

  8. Fast semi-analytical solution of Maxwell's equations in Born approximation for periodic structures.

    Science.gov (United States)

    Pisarenco, Maxim; Quintanilha, Richard; van Kraaij, Mark G M M; Coene, Wim M J

    2016-04-01

    We propose a fast semi-analytical approach for solving Maxwell's equations in Born approximation based on the Fourier modal method (FMM). We show that, as a result of Born approximation, most matrices in the FMM algorithm become diagonal, thus allowing a reduction of computational complexity from cubic to linear. Moreover, due to the analytical representation of the solution in the vertical direction, the number of degrees of freedom in this direction is independent of the wavelength. The method is derived for planar illumination with two basic polarizations (TE/TM) and an arbitrary 2D geometry infinitely periodic in one horizontal direction.

  9. Global existence of periodic solutions on a simplified BAM neural network model with delays

    International Nuclear Information System (INIS)

    Zheng Baodong; Zhang Yazhuo; Zhang Chunrui

    2008-01-01

    A simplified n-dimensional BAM neural network model with delays is considered. Some results of Hopf bifurcations occurring at the zero equilibrium as the delay increases are exhibited. Global existence of periodic solutions are established using a global Hopf bifurcation result of Wu [Wu J. Symmetric functional-differential equations and neural networks with memory. Trans Am Math Soc 1998;350:4799-838], and a Bendixson criterion for higher dimensional ordinary differential equations due to Li and Muldowney [Li MY, Muldowney J. On Bendixson's criterion. J Differ Equations 1994;106:27-39]. Finally, computer simulations are performed to illustrate the analytical results found

  10. Global exponential stability of periodic solution for shunting inhibitory CNNs with delays

    International Nuclear Information System (INIS)

    Li Yongkun; Liu Chunchao; Zhu Lifei

    2005-01-01

    By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, we study the existence and stability of periodic solution for shunting inhibitory cellular neural networks (SICNNs) with delays x-bar ij (t)=-a ij (t)x ij (t)--bar B kl -bar Nr(i,j)B ij kl (t)f ij (x kl (t))x ij (t)--bar C kl -bar Nr(i,j)C ij kl (t)g ij (x kl (t-τ kl ))x ij (t)+L ij (t)

  11. Global exponential stability and existence of periodic solutions of CNNs with delays

    Science.gov (United States)

    Dong, Meifang

    2002-07-01

    In this Letter, we establish general sufficient conditions for global exponential stability and existence of periodic solutions of a class of cellular neural networks (CNNs) with delays. The key to proving the sufficient conditions is the construction of a new Lyapunov functional. An elementary inequality, which may be of independent interest, has been employed in the proof. Checking the sufficient conditions is often reduced to checking some algebraic relations among certain set of parameter. Our sufficient conditions recover the known results in literature as special cases. Finally, we give two examples to illustrate the usage of our main results.

  12. Existence and exponential stability for anti-periodic solutions for shunting inhibitory cellular neural networks with continuously distributed delays

    Directory of Open Access Journals (Sweden)

    Yuanheng Wu

    2009-08-01

    Full Text Available This article concerns anti-periodic solutions for shunting inhibitory cellular neural networks (SICNNs, with continuously distributed delays, arising from the description of the neurons state in delayed neural networks. Without assuming global Lipschitz conditions of activation functions, we obtain existence and local exponential stability of anti-periodic solutions.

  13. Critical experiments on an enriched uranium solution system containing periodically distributed strong thermal neutron absorbers

    International Nuclear Information System (INIS)

    Rothe, R.E.

    1996-01-01

    A series of 62 critical and critical approach experiments were performed to evaluate a possible novel means of storing large volumes of fissile solution in a critically safe configuration. This study is intended to increase safety and economy through use of such a system in commercial plants which handle fissionable materials in liquid form. The fissile solution's concentration may equal or slightly exceed the minimum-critical-volume concentration; and experiments were performed for high-enriched uranium solution. Results should be generally applicable in a wide variety of plant situations. The method is called the 'Poisoned Tube Tank' because strong neutron absorbers (neutron poisons) are placed inside periodically spaced stainless steel tubes which separate absorber material from solution, keeping the former free of contamination. Eight absorbers are investigated. Both square and triangular pitched lattice patterns are studied. Ancillary topics which closely model typical plant situations are also reported. They include the effect of removing small bundles of absorbers as might occur during inspections in a production plant. Not taking the tank out of service for these inspections would be an economic advantage. Another ancillary topic studies the effect of the presence of a significant volume of unpoisoned solution close to the Poisoned Tube Tank on the critical height. A summary of the experimental findings is that boron compounds were excellent absorbers, as expected. This was true for granular materials such as Gerstley Borate and Borax; but it was also true for the flexible solid composed of boron carbide and rubber, even though only thin sheets were used. Experiments with small bundles of absorbers intentionally removed reveal that quite reasonable tanks could be constructed that would allow a few tubes at a time to be removed from the tank for inspection without removing the tank from production service

  14. Periodic solutions of Lienard differential equations via averaging theory of order two

    Directory of Open Access Journals (Sweden)

    JAUME LLIBRE

    2015-12-01

    Full Text Available Abstract For ε ≠ 0sufficiently small we provide sufficient conditions for the existence of periodic solutions for the Lienard differential equations of the form x ′′ + f ( x x ′ + n 2 x + g ( x = ε 2 p 1 ( t + ε 3 p 2 ( t , where n is a positive integer, f : ℝ → ℝis a C 3function, g : ℝ → ℝis a C 4function, and p i : ℝ → ℝfor i = 1 , 2are continuous 2 π–periodic function. The main tool used in this paper is the averaging theory of second order. We also provide one application of the main result obtained.

  15. Periodic solutions of Lienard differential equations via averaging theory of order two.

    Science.gov (United States)

    Llibre, Jaume; Novaes, Douglas D; Teixeira, Marco A

    2015-01-01

    For ε ≠ 0 sufficiently small we provide sufficient conditions for the existence of periodic solutions for the Lienard differential equations of the form x'' + f ⁢(x)⁢ x' + n2⁢x + g (x) = ε2p1 ⁢(t) + ε3 ⁢p2(t), where n is a positive integer, f : ℝ → ℝ is a C 3 function, g : ℝ → ℝ is a C 4 function, and p i : ℝ → ℝ for i = 1, 2 are continuous 2π-periodic function. The main tool used in this paper is the averaging theory of second order. We also provide one application of the main result obtained.

  16. Stability of Almost Periodic Solution for a General Class of Discontinuous Neural Networks with Mixed Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Yingwei Li

    2013-01-01

    Full Text Available The global exponential stability issues are considered for almost periodic solution of the neural networks with mixed time-varying delays and discontinuous neuron activations. Some sufficient conditions for the existence, uniqueness, and global exponential stability of almost periodic solution are achieved in terms of certain linear matrix inequalities (LMIs, by applying differential inclusions theory, matrix inequality analysis technique, and generalized Lyapunov functional approach. In addition, the existence and asymptotically almost periodic behavior of the solution of the neural networks are also investigated under the framework of the solution in the sense of Filippov. Two simulation examples are given to illustrate the validity of the theoretical results.

  17. Efficient and stable solution-processed planar perovskite solar cells via contact passivation

    KAUST Repository

    Tan, Hairen

    2017-02-03

    Planar perovskite solar cells (PSCs) made entirely via solution processing at low temperatures (<150°C) offer promise for simple manufacturing, compatibility with flexible substrates, and perovskite-based tandem devices. However, these PSCs require an electron-selective layer that performs well with similar processing. We report a contact-passivation strategy using chlorine-capped TiO2 colloidal nanocrystal film that mitigates interfacial recombination and improves interface binding in low-temperature planar solar cells. We fabricated solar cells with certified efficiencies of 20.1 and 19.5% for active areas of 0.049 and 1.1 square centimeters, respectively, achieved via low-temperature solution processing. Solar cells with efficiency greater than 20% retained 90% (97% after dark recovery) of their initial performance after 500 hours of continuous room-temperature operation at their maximum power point under 1-sun illumination (where 1 sun is defined as the standard illumination at AM1.5, or 1 kilowatt/square meter).

  18. Comparison of two maintenance electrolyte solutions in children in the postoperative appendectomy period: a randomized, controlled trial

    Directory of Open Access Journals (Sweden)

    Maria Clara da Silva Valadão

    2015-09-01

    Conclusions: In the post‐appendectomy period, the use of hypotonic solution (30 mEq/L, 0.18% did not increase the risk of hyponatremia when compared to isotonic saline. The use of isotonic solution (150 mEq/L, 0.9% did not favor hypernatremia in these patients. Children who received hypotonic solution showed higher cumulative fluid balance in the preoperative period.

  19. Stable-isotope and solute-chemistry approaches to flow characterization in a forested tropical watershed, Luquillo Mountains, Puerto Rico

    Science.gov (United States)

    Scholl, Martha A.; Shanley, James B.; Murphy, Sheila F.; Willenbring, Jane K; Occhi, Marcie; González, Grizelle

    2015-01-01

    The prospect of changing climate has led to uncertainty about the resilience of forested mountain watersheds in the tropics. In watersheds where frequent, high rainfall provides ample runoff, we often lack understanding of how the system will respond under conditions of decreased rainfall or drought. Factors that govern water supply, such as recharge rates and groundwater storage capacity, may be poorly quantified. This paper describes 8-year data sets of water stable isotope composition (δ2H and δ18O) of precipitation (4 sites) and a stream (1 site), and four contemporaneous stream sample sets of solute chemistry and isotopes, used to investigate watershed response to precipitation inputs in the 1780-ha Río Mameyes basin in the Luquillo Mountains of northeastern Puerto Rico. Extreme δ2H and δ18O values from low-pressure storm systems and the deuterium excess (d-excess) were useful tracers of watershed response in this tropical system. A hydrograph separation experiment performed in June 2011 yielded different but complementary information from stable isotope and solute chemistry data. The hydrograph separation results indicated that 36% of the storm rain that reached the soil surface left the watershed in a very short time as runoff. Weathering-derived solutes indicated near-stream groundwater was displaced into the stream at the beginning of the event, followed by significant dilution. The more biologically active solutes exhibited a net flushing behavior. The d-excess analysis suggested that streamflow typically has a recent rainfall component (∼25%) with transit time less than the sampling resolution of 7 days, and a more well-mixed groundwater component (∼75%). The contemporaneous stream sample sets showed an overall increase in dissolved solute concentrations with decreasing elevation that may be related to groundwater inputs, different geology, and slope position. A considerable amount of water from rain events runs off as quickflow and bypasses

  20. Pyridine and phosphonate containing ligands for stable lanthanide complexation. An experimental and theoretical study to assess the solution structure.

    Science.gov (United States)

    Mato-Iglesias, Marta; Balogh, Edina; Platas-Iglesias, Carlos; Tóth, Eva; de Blas, Andrés; Rodríguez Blas, Teresa

    2006-12-07

    We report an experimental and theoretical study of the stability and solution structure of lanthanide complexes with two novel ligands containing pyridine units and phosphonate pendant arms on either ethane-1,2-diamine (L2) or cyclohexane-1,2-diamine (L3) backbones. Potentiometric studies have been carried out to determine the protonation constants of the ligands and the stability constants of the complexes with Gd(III) and the endogenous metal ions Zn(II) and Cu(II). While the stability constant of the GdL2 complex is too high to be determined by direct pH-potentiometric titrations, the cyclohexyl derivative GdL3 has a lower and assessable stability (log K(GdL3)=17.62). Due to the presence of the phosphonate groups, various protonated species can be detected up to pH approximately 8 for both ligands and all metal ions studied. The molecular clusters [Ln(L)(H2O)](3-).19H2O (Ln=La, Nd, Ho or Lu; L=L2 or L3) were characterized by theoretical calculations at the HF level. Our calculations provide two minimum energy geometries where the ligand adopts different conformations: twist-wrap (tw), in which the ligand wraps around the metal ion by twisting the pyridyl units relative to each other, and twist-fold (tf), where the slight twisting of the pyridyl units is accompanied by an overall folding of the two pyridine units towards one of the phosphonate groups. The relative free energies of the tw and tf conformations of [Ln(L)(H2O)]3- (L=L2, L3) complexes calculated in aqueous solution (C-PCM) by using the B3LYP model indicate that the tw form is the most stable one along the whole lanthanide series for the complexes of L3, while for those of L2 only the Gd(III) complex is more stable in the tf conformation by ca. 0.5 kcal mol-1. 1H NMR studies of the Eu(III) complex of L3 show the initial formation of the tf complex in aqueous solution, which slowly converts to the thermodynamically stable tw form. The structures calculated for the Nd(III) complexes are in reasonably

  1. Different immersion periods and aqueous solutions effects upon the corrosion resistance of zinc and aluminium specimens

    Directory of Open Access Journals (Sweden)

    Osório, W. R.

    2005-12-01

    Full Text Available Several metallic materials form spontaneously an oxide film at the surface when is exposed in a corrosive environment. It is well known that the type of corrosive media may develop different results at the material corrosion resistance. The aim of the present paper is to investigate the influence of immersion periods and different solutions upon the corrosion resistance of pure Zn and Al specimens presenting different grain morphologies. The specimens were monitored for several periods in a 3 % NaCl solution at room temperature. Tests were also performed with variations of the 3 % NaCl solution modified by additions of acid and alkaline components. Both the electrochemical impedance spectroscopy (EIS and polarization methods were applied.

    Algunos materiales metálicos, cuando se encuentran en un entorno corrosivo, forman espontáneamente una película de óxido en su superficie. Se sabe que los medios corrosivos pueden dar resultados diferentes, según sea la resistencia a la corrosión del material. El propósito del siguiente trabajo es investigar la influencia de los períodos de inmersión en diferentes soluciones sobre la resistencia a la corrosión de probetas de cinc y aluminio puros, con morfologías de grano diferentes. Las probetas fueron ensayadas durante varios períodos de tiempo en soluciones de NaCl 3 % y también con adiciones de ácidos y bases. Se utilizaron las técnicas de espectrometría de impedancia electroquímica (EIS y de polarización.

  2. Localized and periodic exact solutions to the nonlinear Schroedinger equation with spatially modulated parameters: Linear and nonlinear lattices

    International Nuclear Information System (INIS)

    Belmonte-Beitia, Juan; Konotop, Vladimir V.; Perez-Garcia, Victor M.; Vekslerchik, Vadym E.

    2009-01-01

    Using similarity transformations we construct explicit solutions of the nonlinear Schroedinger equation with linear and nonlinear periodic potentials. We present explicit forms of spatially localized and periodic solutions, and study their properties. We put our results in the framework of the exploited perturbation techniques and discuss their implications on the properties of associated linear periodic potentials and on the possibilities of stabilization of gap solitons using polychromatic lattices.

  3. Thermally Stable Solution Processed Vanadium Oxide as a Hole Extraction Layer in Organic Solar Cells.

    Science.gov (United States)

    Alsulami, Abdullah; Griffin, Jonathan; Alqurashi, Rania; Yi, Hunan; Iraqi, Ahmed; Lidzey, David; Buckley, Alastair

    2016-03-25

    Low-temperature solution-processable vanadium oxide (V₂O x ) thin films have been employed as hole extraction layers (HELs) in polymer bulk heterojunction solar cells. V₂O x films were fabricated in air by spin-coating vanadium(V) oxytriisopropoxide (s-V₂O x ) at room temperature without the need for further thermal annealing. The deposited vanadium(V) oxytriisopropoxide film undergoes hydrolysis in air, converting to V₂O x with optical and electronic properties comparable to vacuum-deposited V₂O₅. When s-V₂O x thin films were annealed in air at temperatures of 100 °C and 200 °C, OPV devices showed similar results with good thermal stability and better light transparency. Annealing at 300 °C and 400 °C resulted in a power conversion efficiency (PCE) of 5% with a decrement approximately 15% lower than that of unannealed films; this is due to the relative decrease in the shunt resistance (R sh ) and an increase in the series resistance (R s ) related to changes in the oxidation state of vanadium.

  4. Applications of MMPBSA to Membrane Proteins I: Efficient Numerical Solutions of Periodic Poisson-Boltzmann Equation.

    Science.gov (United States)

    Botello-Smith, Wesley M; Luo, Ray

    2015-10-26

    Continuum solvent models have been widely used in biomolecular modeling applications. Recently much attention has been given to inclusion of implicit membranes into existing continuum Poisson-Boltzmann solvent models to extend their applications to membrane systems. Inclusion of an implicit membrane complicates numerical solutions of the underlining Poisson-Boltzmann equation due to the dielectric inhomogeneity on the boundary surfaces of a computation grid. This can be alleviated by the use of the periodic boundary condition, a common practice in electrostatic computations in particle simulations. The conjugate gradient and successive over-relaxation methods are relatively straightforward to be adapted to periodic calculations, but their convergence rates are quite low, limiting their applications to free energy simulations that require a large number of conformations to be processed. To accelerate convergence, the Incomplete Cholesky preconditioning and the geometric multigrid methods have been extended to incorporate periodicity for biomolecular applications. Impressive convergence behaviors were found as in the previous applications of these numerical methods to tested biomolecules and MMPBSA calculations.

  5. Cu-Containing Fe-Ni Corrosion-Resistant Alloys Designed by a Cluster-Based Stable Solid Solution Model

    Science.gov (United States)

    Li, Baozeng; Wang, Qing; Wang, Yingmin; Li, Chunyan; Qiang, Jianbing; Ji, Chunjun; Dong, Chuang

    2012-02-01

    Copper is a good corrosion resisting element, but due to its immiscibility with Fe, it is only used as a minor-alloying element in stainless steels. In this work, we introduced a double-cluster structure model [CuNi12][NiFe12] m for stable solid solutions in Cu-containing Fe-Ni corrosion-resistant invar alloys. Our model takes into account all of the enthalpies between the element pairs by assuming Fe-Ni and Ni-Cu nearest neighbors and by avoiding Fe-Cu ones, so that the ideally stabilized structures are described by mixing two cuboctahedral clusters in the fcc lattice, NiFe12 and CuNi12. Two alloy series were designed by varying the relative proportions of the two clusters and the Cu contents. It was proved that the alloys with Cu contents below those prescribed by this model could easily be solutionized and water-quenched to a monolithic fcc solid solution, and resultant alloys possessed good corrosion-resisting properties in 3.5 wt pct NaCl solution.

  6. Fictitious Domain Technique for the Calculation of Time-Periodic Solutions of Scattering Problem

    Directory of Open Access Journals (Sweden)

    Ling Rao

    2011-01-01

    Full Text Available The fictitious domain technique is coupled to the improved time-explicit asymptotic method for calculating time-periodic solution of wave equation. Conventionally, the practical implementation of fictitious domain method relies on finite difference time discretizations schemes and finite element approximation. Our new method applies finite difference approximations in space instead of conventional finite element approximation. We use the Dirac delta function to transport the variational forms of the wave equations to the differential form and then solve it by finite difference schemes. Our method is relatively easier to code and requires fewer computational operations than conventional finite element method. The numerical experiments show that the new method performs as well as the method using conventional finite element approximation.

  7. Global exponential stability of periodic solution for shunting inhibitory CNNs with delays

    Energy Technology Data Exchange (ETDEWEB)

    Li Yongkun [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China)]. E-mail: yklie@ynu.edu.cn; Liu Chunchao [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China); Zhu Lifei [Department of Mathematics, Yunnan University, Kunming, Yunnan 650091 (China)

    2005-03-28

    By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, we study the existence and stability of periodic solution for shunting inhibitory cellular neural networks (SICNNs) with delays x-bar {sub ij}(t)=-a{sub ij}(t)x{sub ij}(t)--bar B{sup kl}-bar Nr(i,j)B{sub ij}{sup kl}(t)f{sub ij}(x{sub kl}(t))x{sub ij}(t)--bar C{sup kl}-bar Nr(i,j)C{sub ij}{sup kl}(t)g{sub ij}(x{sub kl}(t-{tau}{sub kl}))x{sub ij}(t)+L{sub ij}(t)

  8. Periodic solutions for a non-monotone family of delayed differential equations with applications to Nicholson systems

    Science.gov (United States)

    Faria, Teresa

    2017-07-01

    For a family of n-dimensional periodic delay differential equations which encompasses a broad set of models used in structured population dynamics, the existence of a positive periodic solution is obtained under very mild conditions. The proof uses the Schauder fixed point theorem and relies on the permanence of the system. A general criterion for the existence of a positive periodic solution for Nicholson's blowflies periodic systems (with both distributed and discrete time-varying delays) is derived as a simple application of our main result, generalizing the few existing results concerning multi-dimensional Nicholson models. In the case of a Nicholson system with discrete delays all multiples of the period, the global attractivity of the positive periodic solution is further analyzed, improving results in recent literature.

  9. Multi-period natural gas market modeling Applications, stochastic extensions and solution approaches

    Science.gov (United States)

    Egging, Rudolf Gerardus

    This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. 1 The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in

  10. Multi-Period Natural Gas Market Modeling. Applications, Stochastic Extensions and Solution Approaches

    International Nuclear Information System (INIS)

    Egging, R.G.

    2010-11-01

    This dissertation develops deterministic and stochastic multi-period mixed complementarity problems (MCP) for the global natural gas market, as well as solution approaches for large-scale stochastic MCP. The deterministic model is unique in the combination of the level of detail of the actors in the natural gas markets and the transport options, the detailed regional and global coverage, the multi-period approach with endogenous capacity expansions for transportation and storage infrastructure, the seasonal variation in demand and the representation of market power according to Nash-Cournot theory. The model is applied to several scenarios for the natural gas market that cover the formation of a cartel by the members of the Gas Exporting Countries Forum, a low availability of unconventional gas in the United States, and cost reductions in long-distance gas transportation. The results provide insights in how different regions are affected by various developments, in terms of production, consumption, traded volumes, prices and profits of market participants. The stochastic MCP is developed and applied to a global natural gas market problem with four scenarios for a time horizon until 2050 with nineteen regions and containing 78,768 variables. The scenarios vary in the possibility of a gas market cartel formation and varying depletion rates of gas reserves in the major gas importing regions. Outcomes for hedging decisions of market participants show some significant shifts in the timing and location of infrastructure investments, thereby affecting local market situations. A first application of Benders decomposition (BD) is presented to solve a large-scale stochastic MCP for the global gas market with many hundreds of first-stage capacity expansion variables and market players exerting various levels of market power. The largest problem solved successfully using BD contained 47,373 variables of which 763 first-stage variables, however using BD did not result in

  11. Singular 1-soliton and Periodic Solutions to the Nonlinear Fisher-Type Equation with Time-Dependent Coefficients

    Science.gov (United States)

    Ozkan, Guner; Ahmet, Bekir

    2016-04-01

    In this article, we establish exact solutions for the variable-coefficient Fisher-type equation. The solutions are obtained by the modified sine-cosine method and ansatz method. The soliton and periodic solutions and topological as well as the singular 1-soliton solution are obtained with the aid of the ansatz method. These solutions are important for the explanation of some practical physical problems. The obtained results show that these methods provide a powerful mathematical tool for solving nonlinear equations with variable coefficients.

  12. Exact solutions to plaquette Ising models with free and periodic boundaries

    International Nuclear Information System (INIS)

    Mueller, Marco; Johnston, Desmond A.; Janke, Wolfhard

    2017-01-01

    An anisotropic limit of the 3d plaquette Ising model, in which the plaquette couplings in one direction were set to zero, was solved for free boundary conditions by Suzuki (1972) , who later dubbed it the fuki-nuke, or “no-ceiling”, model. Defining new spin variables as the product of nearest-neighbour spins transforms the Hamiltonian into that of a stack of (standard) 2d Ising models and reveals the planar nature of the magnetic order, which is also present in the fully isotropic 3d plaquette model. More recently, the solution of the fuki-nuke model was discussed for periodic boundary conditions, which require a different approach to defining the product spin transformation, by Castelnovo et al. (2010) . We clarify the exact relation between partition functions with free and periodic boundary conditions expressed in terms of original and product spin variables for the 2d plaquette and 3d fuki-nuke models, noting that the differences are already present in the 1d Ising model. In addition, we solve the 2d plaquette Ising model with helical boundary conditions. The various exactly solved examples illustrate how correlations can be induced in finite systems as a consequence of the choice of boundary conditions.

  13. Caution on the storage of waters and aqueous solutions in plastic containers for hydrogen and oxygen stable isotope analysis.

    Science.gov (United States)

    Spangenberg, Jorge E

    2012-11-30

    The choice of containers for storage of aqueous samples between their collection, transport and water hydrogen ((2)H) and oxygen ((18)O) stable isotope analysis is a topic of concern for a wide range of fields in environmental, geological, biomedical, food, and forensic sciences. The transport and separation of water molecules during water vapor or liquid uptake by sorption or solution and the diffusive transport of water molecules through organic polymer material by permeation or pervaporation may entail an isotopic fractionation. An experiment was conducted to evaluate the extent of such fractionation. Sixteen bottle-like containers of eleven different organic polymers, including low and high density polyethylene (LDPE and HDPE), polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), and perfluoroalkoxy-Teflon (PFA), of different wall thickness and size were completely filled with the same mineral water and stored for 659 days under the same conditions of temperature and humidity. Particular care was exercised to keep the bottles tightly closed and prevent loss of water vapor through the seals. Changes of up to +5‰ for δ(2)H values and +2.0‰ for δ(18)O values were measured for water after more than 1 year of storage within a plastic container, with the magnitude of change depending mainly on the type of organic polymer, wall thickness, and container size. The most important variations were measured for the PET and PC bottles. Waters stored in glass bottles with Polyseal™ cone-lined PP screw caps and thick-walled HDPE or PFA containers with linerless screw caps having an integrally molded inner sealing ring preserved their original δ(2)H and δ(18)O values. The carbon, hydrogen, and oxygen stable isotope compositions of the organic polymeric materials were also determined. The results of this study clearly show that for precise and accurate measurements of the water stable isotope composition in aqueous solutions, rigorous sampling and

  14. Existence and Asymptotic Stability of Periodic Solutions of the Reaction-Diffusion Equations in the Case of a Rapid Reaction

    Science.gov (United States)

    Nefedov, N. N.; Nikulin, E. I.

    2018-01-01

    A singularly perturbed periodic in time problem for a parabolic reaction-diffusion equation in a two-dimensional domain is studied. The case of existence of an internal transition layer under the conditions of balanced and unbalanced rapid reaction is considered. An asymptotic expansion of a solution is constructed. To justify the asymptotic expansion thus constructed, the asymptotic method of differential inequalities is used. The Lyapunov asymptotic stability of a periodic solution is investigated.

  15. Type-D personality is a stable taxonomy in post-MI patients over an 18-month period

    DEFF Research Database (Denmark)

    Martens, Elisabeth J; Kupper, Nina; Pedersen, Susanne S.

    2007-01-01

    type-D personality comprises a risk factor for adverse prognosis in patients with cardiovascular disease (CVD). However, concerns that type-D personality may not be a stable personality taxonomy and that progression of CVD may contribute to the manifestation of type-D personality have been voiced...

  16. Existence and asymptotic estimates of periodic solutions of El Niño mechanism of atmospheric physics

    International Nuclear Information System (INIS)

    Xiao-Jing, Li

    2010-01-01

    This paper is devoted to studying the El Niño mechanism of atmospheric physics. The existence and asymptotic estimates of periodic solutions for its model are obtained by employing the technique of upper and lower solution, and using the continuation theorem of coincidence degree theory. (general)

  17. Fate of process solution cyanide and nitrate at three nevada gold mines inferred from stable carbon and nitrogen isotope measurements

    Science.gov (United States)

    Johnson, C.A.; Grimes, D.J.; Rye, R.O.

    2000-01-01

    Stable isotope methods have been used to identify the mechanisms responsible for cyanide consumption at three heap-leach operations that process Carlin-type gold ores in Nevada, U.S.A. The reagent cyanide had ??15N values ranging from -5 to -2??? and ??13C values from -60 to -35???. The wide ??13C range reflects the use by different suppliers of isotopically distinct natural-gas feedstocks and indicates that isotopes may be useful in environmental studies where there is a need to trace cyanide sources. In heap-leach circuits displaying from 5 to 98% consumption of cyanide, barren-solution and pregnant-solution cyanide were isotopically indistinguishable. The similarity is inconsistent with cyanide loss predominantly by HCN offgassing (a process that in laboratory experiments caused substantial isotopic changes), but it is consistent with cyanide retention within the heaps as solids, a process that caused minimal isotopic changes in laboratory simulations, or with cyanide oxidation, which also appears to cause minimal changes. In many pregnant solutions cyanide was carried entirely as metal complexes, which is consistent with ferrocyanides having precipitated or cyanocomplexes having been adsorbed within the heaps. It is inferred that gaseous cyanide emissions from operations of this type are less important than has generally been thought and that the dissolution or desorption kinetics of solid species is an important control on cyanide elution when the spent heaps undergo rinsing. Nitrate, nitrite and ammonium had ??15N values of 1-16???. The data reflect isotopic fractionation during ammonia offgassing or denitrification of nitrate - particularly in reclaim ponds - but do not indicate the extent to which nitrate is derived from cyanide or from explosive residues. ?? The Institution of Mining and Metallurgy 2000.

  18. Calcium biogeochemical cycle at the beech tree-soil solution interface from the Strengbach CZO (NE France): insights from stable Ca and radiogenic Sr isotopes

    Science.gov (United States)

    Schmitt, Anne-Désirée; Gangloff, Sophie; Labolle, François; Chabaux, François; Stille, Peter

    2017-09-01

    Calcium (Ca) is the fourth most abundant element in mineral nutrition and plays key physiological and structural roles in plant metabolism. At the soil-water-plant scale, stable Ca isotopes are a powerful tool for the identification of plant-mineral interactions and recycling via vegetation. Radiogenic Sr isotopes are often used as tracers of Ca sources and mixtures of different reservoirs. In this study, stable Ca and radiogenic Sr are combined and analysed in several organs from two beech trees that were collected in June and September in the Strengbach critical zone observatory (CZO) (NE France) and in corresponding soil solutions. At the beech-tree scale, this study confirms the field Ca adsorption (i.e., physico-chemical mechanism and not vital effects) on carboxyl acid groups of pectin in the apoplasm of small roots. The analysis of the xylem sap and corresponding organs shows that although the Strengbach CZO is nutrient-poor, Ca seems to be non-limiting for tree-growth. Different viscosities of xylem sap between the stemwood and branches or leaves can explain δ44/40Ca values in different tree-organs. The bark and phloem 40Ca-enrichments could be due to Ca-oxalate precipitation in the bark tissues and in the phloem. The results from this study regarding the combination of these two isotopic systems show that the isotopic signatures of the roots are dominated by Ca fractionation mechanisms and Sr, and thus Ca, source variations. In contrast, translocation mechanisms are only governed by Ca fractionation processes. This study showed that at the root-soil solution interface, litter degradation was not the main source of Ca and Sr and that the soil solutions are not the complement of uptake by roots for samples from the 2011/2013 period. The opposite is observed for older samples. These observations indicate the decreasing contribution of low radiogenic Sr fluxes, such as recycling, alimenting the soil solutions. Such reduced importance of nutrient uptake and

  19. Generalized Bilinear Differential Operators, Binary Bell Polynomials, and Exact Periodic Wave Solution of Boiti-Leon-Manna-Pempinelli Equation

    Directory of Open Access Journals (Sweden)

    Huanhe Dong

    2014-01-01

    Full Text Available We introduce how to obtain the bilinear form and the exact periodic wave solutions of a class of (2+1-dimensional nonlinear integrable differential equations directly and quickly with the help of the generalized Dp-operators, binary Bell polynomials, and a general Riemann theta function in terms of the Hirota method. As applications, we solve the periodic wave solution of BLMP equation and it can be reduced to soliton solution via asymptotic analysis when the value of p is 5.

  20. Sparse grid spectral methods for the numerical solution of partial differential equations with periodic boundary conditions

    International Nuclear Information System (INIS)

    Kupka, F.

    1997-11-01

    This thesis deals with the extension of sparse grid techniques to spectral methods for the solution of partial differential equations with periodic boundary conditions. A review on boundary and initial-boundary value problems and a discussion on numerical resolution is used to motivate this research. Spectral methods are introduced by projection techniques, and by three model problems: the stationary and the transient Helmholtz equations, and the linear advection equation. The approximation theory on the hyperbolic cross is reviewed and its close relation to sparse grids is demonstrated. This approach extends to non-periodic problems. Various Sobolev spaces with dominant mixed derivative are introduced to provide error estimates for Fourier approximation and interpolation on the hyperbolic cross and on sparse grids by means of Sobolev norms. The theorems are immediately applicable to the stability and convergence analysis of sparse grid spectral methods. This is explicitly demonstrated for the three model problems. A variant of the von Neumann condition is introduced to simplify the stability analysis of the time-dependent model problems. The discrete Fourier transformation on sparse grids is discussed together with its software implementation. Results on numerical experiments are used to illustrate the performance of the new method with respect to the smoothness properties of each example. The potential of the method in mathematical modelling is estimated and generalizations to other sparse grid methods are suggested. The appendix includes a complete Fortran90 program to solve the linear advection equation by the sparse grid Fourier collocation method and a third-order Runge-Kutta routine for integration in time. (author)

  1. Grout Spread and Injection Period of Silica Solution and Cement Mix in Rock Fractures

    Science.gov (United States)

    El Tani, Mohamed; Stille, Håkan

    2017-09-01

    A systematic presentation of the analytic relations of grout spread to the time period is established. They are divided following the nature of the flow, the property of the mix and the driving process. This includes channel flow between parallel plates and radial flow between parallel discs, nonlinear Newtonian fluids like silica solution, polyurethane and epoxy, and Bingham material like cement-based grout, and three grouting processes at a constant flow rate, constant pressure and constant energy. The analytic relations for the constant energy process are new and complete the relations of the constant flow rate and constant pressure processes. The well-known statement that refusal cannot be obtained during finite time for any injected material at a constant flow rate or constant injection pressure is extended to include the energy process. The term refusal pressure or energy cannot be supported for stop criteria. Stop criteria have to be defined considering confirmed relation of the spread to the time period and of the flow rate to the pressure and spread. It is shown that it is always possible to select a grouting process along which the work will exceed any predefined energy, the consequence of which is that jacking is related to the applied forces and not to the injected energy. Furthermore, a clarification is undertaken concerning the radial flow rate of a Bingham material since there are two different formulations. Their difference is explained and quantified. Finally, it is shown that the applied Lugeon theory is not supported by the analytic relations and needs to be substantially modified.

  2. Active and Stable Methane Oxidation Nano-Catalyst with Highly-Ionized Palladium Species Prepared by Solution Combustion Synthesis

    Directory of Open Access Journals (Sweden)

    Mahmoud M. Khader

    2018-02-01

    Full Text Available We report on the synthesis and testing of active and stable nano-catalysts for methane oxidation. The nano-catalyst was palladium/ceria supported on alumina prepared via a one-step solution-combustion synthesis (SCS method. As confirmed by X-ray photoelectron spectroscopy (XPS and high-resolution transmission electron microscopy (HTEM, SCS preparative methodology resulted in segregating both Pd and Ce on the surface of the Al2O3 support. Furthermore, HTEM showed that bigger Pd particles (5 nm and more were surrounded by CeO2, resembling a core shell structure, while smaller Pd particles (1 nm and less were not associated with CeO2. The intimate Pd-CeO2 attachment resulted in insertion of Pd ions into the ceria lattice, and associated with the reduction of Ce4+ into Ce3+ ions; consequently, the formation of oxygen vacancies. XPS showed also that Pd had three oxidation states corresponding to Pd0, Pd2+ due to PdO, and highly ionized Pd ions (Pd(2+x+ which might originate from the insertion of Pd ions into the ceria lattice. The formation of intrinsic Ce3+ ions, highly ionized (Pd2+ species inserted into the lattice of CeO2 Pd ions (Pd(2+x+ and oxygen vacancies is suggested to play a major role in the unique catalytic activity. The results indicated that the Pd-SCS nano-catalysts were exceptionally more active and stable than conventional catalysts. Under similar reaction conditions, the methane combustion rate over the SCS catalyst was ~18 times greater than that of conventional catalysts. Full methane conversions over the SCS catalysts occurred at around 400 °C but were not shown at all with conventional catalysts. In addition, contrary to the conventional catalysts, the SCS catalysts exhibited superior activity with no sign of deactivation in the temperature range between ~400 and 800 °C.

  3. Almost-Periodic Weak Solutions of Second-Order Neutral Delay-Differential Equations with Piecewise Constant Argument

    Directory of Open Access Journals (Sweden)

    Wang Li

    2008-01-01

    Full Text Available We investigate the existence of almost-periodic weak solutions of second-order neutral delay-differential equations with piecewise constant argument of the form , where denotes the greatest integer function, is a real nonzero constant, and is almost periodic.

  4. Global Exponential Stability of Positive Almost Periodic Solutions for a Fishing Model with a Time-Varying Delay

    Directory of Open Access Journals (Sweden)

    Hong Zhang

    2014-01-01

    Full Text Available This paper is concerned with a nonautonomous fishing model with a time-varying delay. Under proper conditions, we employ a novel argument to establish a criterion on the global exponential stability of positive almost periodic solutions of the model with almost periodic coefficients and delays. Moreover, an example and its numerical simulation are given to illustrate the main results.

  5. Existence of quasi-periodic solutions of fast excited van der Pol-Mathieu-Duffing equation

    Science.gov (United States)

    Lu, Lin; Li, Xuemei

    2015-12-01

    The van der Pol-Mathieu-Duffing equation x ̈ + ( Ω0 2 + h 1 cos Ω 1 t + h 2 cos Ω 2 t ) x - ( α - β x 2 ) x ˙ - h 3 x 3 = h 4 Ω3 2 cos x cos Ω 3 t is considered in this paper, where α, β, h1, h2, h3, h4, Ω1, Ω2 are small parameters, α, β > 0, the frequency Ω3 is large compared to Ω1 and Ω2, the above parameters are real. For ∀α, β > 0, we use KAM (Kolmogorov-Arnold-Moser) theory to prove that the van der Pol-Mathieu-Duffing equation possesses quasi-periodic solutions for most of the parameters Ω0, Ω1, Ω2, Ω3, it verifies some phenomenon of Fahsi and Belhaq [Commun. Nonlinear Sci. 14, 244-253 (2009)] and can be regarded as a extension of Abouhazim et al. [Nonlinear Dyn. 39, 395-409 (2005)].

  6. Spatial analysis of annual mean stable isotopes in precipitation across Japan based on an intensive observation period throughout 2013.

    Science.gov (United States)

    Ichiyanagi, Kimpei; Tanoue, Masahiro

    2016-01-01

    Spatial distribution of annual mean stable isotopes in precipitation (δ(18)O, δ(2)H) was observed at 56 sites across Japan throughout 2013. Annual mean δ(18)O values showed a strong latitude effect, from -12.4 ‰ in the north to -5.1 ‰ in the south. Annual mean d-excess values ranged from 8 to 21 ‰, and values on the Sea of Japan side in Northern and Eastern Japan were relatively higher than those on the Pacific Ocean side. The local meteoric water line (LMWL) and isotope effects were based on the annual mean values from all sites across Japan as divided into distinct regions: the Sea of Japan side to the Pacific Ocean side and Northeastern to Southwestern Japan. Slopes and intercepts of LMWL ranged from 7.4 to 7.8 and 9.8 to 13.0, respectively. Slopes for latitude, altitude, and temperature effects ranged from -0.27 to -0.48 ‰/°N, -0.0034 to -0.0053 ‰/m, and 0.36 to 0.46 ‰/°C, respectively, with statistically significance at the 99 % level. However, there was no precipitation amount effect. From the result of a multiple regression analysis, the empirical formula of annual mean δ(18)O in precipitation from latitude and altitude for all sites across Japan was determined to be δ(18) O = -0.348 (LAT) - 0.00307 (ALT) + 4.29 (R(2) = 0.59). Slopes for latitude and altitude ranged from - 0.28 to - 0.51, and - 0.0019 to - 0.0045, respectively. Even though site distribution was uneven, these equations are the first trial estimation for annual mean stable isotopes in precipitation across Japan. Further research performed on the monthly basis is required to elucidate factors controlling the spatiotemporal variability of stable isotopes in precipitation across Japan.

  7. Existence and global exponential stability of periodic solution of memristor-based BAM neural networks with time-varying delays.

    Science.gov (United States)

    Li, Hongfei; Jiang, Haijun; Hu, Cheng

    2016-03-01

    In this paper, we investigate a class of memristor-based BAM neural networks with time-varying delays. Under the framework of Filippov solutions, boundedness and ultimate boundedness of solutions of memristor-based BAM neural networks are guaranteed by Chain rule and inequalities technique. Moreover, a new method involving Yoshizawa-like theorem is favorably employed to acquire the existence of periodic solution. By applying the theory of set-valued maps and functional differential inclusions, an available Lyapunov functional and some new testable algebraic criteria are derived for ensuring the uniqueness and global exponential stability of periodic solution of memristor-based BAM neural networks. The obtained results expand and complement some previous work on memristor-based BAM neural networks. Finally, a numerical example is provided to show the applicability and effectiveness of our theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Playing around resonance an invitation to the search of periodic solutions for second order ordinary differential equations

    CERN Document Server

    Fonda, Alessandro

    2016-01-01

    This book provides an up-to-date description of the methods needed to face the existence of solutions to some nonlinear boundary value problems. All important and interesting aspects of the theory of periodic solutions of ordinary differential equations related to the physical and mathematical question of resonance are treated. The author has chosen as a model example the periodic problem for a second order scalar differential equation. In a paedagogical style the author takes the reader step by step from the basics to the most advanced existence results in the field.

  9. On solubility of perchloric (periodic) acid and α-cyanacetanmide in aqueous solutions at 25 deg C

    International Nuclear Information System (INIS)

    Omarova, R.A.; Balysbekov, S.M.; Erkasov, R.Sh.; Nikolenko, O.N.

    1996-01-01

    Acid-base interaction within perchloric (periodic) acid-α-cyanacetamide-water systems in studied by method of solubility under isothermal conditions at 25 deg C. Solubility regularities of crystalline α-cyanacetamide in perchloric and periodic acid solutions are determined, the concentration limits of formation of a new solid phase-tris(α-cyanacetamide) perchlorate within perchloric acid-α-cyanacetamide-water system are determined. The compound is identified by means of chemical and X-ray phase analyses, its density and melting temperature are determined. Iodic acid and α-cyanacetamide water solution base system is shown to belong to a simple eutonic type. 2 refs., 3 figs., 2 tabs

  10. Calcium Hypochlorite Solutions: Evaluation of Surface Tension and Effect of Different Storage Conditions and Time Periods over pH and Available Chlorine Content.

    Science.gov (United States)

    Leonardo, Natália Gomes e Silva; Carlotto, Israel Bangel; Luisi, Simone Bonato; Kopper, Patrícia Maria Poli; Grecca, Fabiana Soares; Montagner, Francisco

    2016-04-01

    The aim of this study was to evaluate the pH and the available chlorine content from sodium hypochlorite (NaOCl) and calcium hypochlorite (Ca[OCl]2) solutions stored in different conditions and time periods and the surface tension of Ca(OCl)2 solutions in comparison with NaOCl. Solutions at 0.5%, 1%, 2.5%, and 5.25% concentrations were prepared. The pH level and the available chlorine content of freshly prepared solutions and solutions stored for 30, 60, and 90 days at 25°C, 4°C, or 37°C were evaluated in a digital pH meter and by titration, respectively. Surface tension was tested using a Du Nouy tensiometer (Sigma 702, Force Tensiometer; Attension, Espoo, Finland). Descriptive and inferential statistical analyses were performed. A precipitate formed by 2.5% and 5.25% Ca(OCl)2 solutions was observed. Ca(OCl)2 showed a higher concentration of available chlorine than NaOCl. Both 2.5% and 5.25% NaOCl and Ca(OCl)2 had a decrease in the available chlorine content when compared with freshly prepared solutions; 0.5% and 1% NaOCl tend to have a lower pH compared with 0.5% and 1% Ca(OCl)2. NaOCl, 5.25%, showed higher pH compared with 5.25% Ca(OCl)2. NaOCl and Ca(OCl)2 in 0.5% and 1% concentrations tend to show a reduced pH level, whereas 2.5% and 5.25% solutions showed an increase in pH. The heat contributed to the instability of the solutions. NaOCl showed lower surface tension values than Ca(OCl)2. Ca(OCl)2 solutions are extremely alkaline and tend to have more available chlorine content than NaOCl but have a higher surface tension than NaOCl. Regarding the available chlorine content, these solutions tend to be stable to 30 days of storage when kept at 4°C or at 25°C. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  11. Photometry of long-period Algol binaries. VI. Multicolor photometric solutions for RZ Cancri

    Energy Technology Data Exchange (ETDEWEB)

    Olson, E.C. (Illinois Univ., Urbana (USA))

    1989-09-01

    New intermediate-band photometry of the late-giant eclipsing system RZ CNc is used to obtain photometric solutions, both with the Popper (1976) spectroscopic mass ratio and by allowing the mass ratio and gravity-darkening coefficients to vary. New y observations are combined with earlier V data of Lenouvel (1957) and Broglia and Conconi (1973) in one solution set. Additional solutions are obtained from the new observations. The mean photometric mass ratio is somewhat larger than Popper's spectroscopic values; the general indeterminacy of photometric solutions may explain this apparent discrepancy. Possible photometric effects of a mass-transferring stream are discussed, and it is concluded that such effects cannot account for the mass-ratio discrepancy. 26 refs.

  12. Periodic Solutions to a Cahn-Hilliard-Willmore Equation in the Plane

    Science.gov (United States)

    Malchiodi, Andrea; Mandel, Rainer; Rizzi, Matteo

    2017-12-01

    In this paper we construct entire solutions to the phase field equation of Willmore type {-Δ(-Δ u+W^'(u))+W^''(u)(-Δ u+W^'(u))=0} in the Euclidean plane, where W(u) is the standard double-well potential {1/4 (1-u^2)^2} . Such solutions have a non-trivial profile that shadows a Willmore planar curve, and converge uniformly to {± 1} as {x_2 \\to ± ∞} . These solutions give a counterexample to the counterpart of Gibbons' conjecture for the fourth-order counterpart of the Allen-Cahn equation. We also study the x 2-derivative of these solutions using the special structure of Willmore's equation.

  13. Stable time patterns of railway suicides in Germany: comparative analysis of 7,187 cases across two observation periods (1995–1998; 2005–2008)

    Science.gov (United States)

    2014-01-01

    Background The majority of fatalities on the European Union (EU) railways are suicides, representing about 60% of all railway fatalities. The aim of this study was to compare time patterns of suicidal behaviour on railway tracks in Germany between two observation periods (1995–1998 and 2005–2008) in order to investigate their stability and value in railway suicide prevention. Methods Cases were derived from the National Central Registry of person accidents on the German railway network (STABAG). The association of daytime, weekday and month with the mean number of suicides was analysed applying linear regression. Potential differences by observation period were assessed by adding observation period and the respective interaction terms into the linear regression. A 95% confidence interval for the mean number of suicides was computed using the t distribution. Results A total of 7,187 railway suicides were recorded within both periods: 4,102 (57%) in the first period (1995–1998) and 3,085 (43%) in the second (2005–2008). The number of railway suicides was highest on Mondays and Tuesdays in the first period with an average of 3.2 and 3.5 events and of 2.6 events on both days in the second period. In both periods, railway suicides were more common between 6:00 am and noon, and between 6:00 pm and midnight. Seasonality was only prominent in the period 1995–1998. Conclusions Over the course of two observation periods, the weekday and circadian patterns of railway suicides remained stable. Therefore, these patterns should be an integral part of railway suicide preventive measures, e.g. gatekeeper training courses. PMID:24498876

  14. Stable time patterns of railway suicides in Germany: comparative analysis of 7,187 cases across two observation periods (1995-1998; 2005-2008).

    Science.gov (United States)

    Lukaschek, Karoline; Baumert, Jens; Erazo, Natalia; Ladwig, Karl-Heinz

    2014-02-06

    The majority of fatalities on the European Union (EU) railways are suicides, representing about 60% of all railway fatalities. The aim of this study was to compare time patterns of suicidal behaviour on railway tracks in Germany between two observation periods (1995-1998 and 2005-2008) in order to investigate their stability and value in railway suicide prevention. Cases were derived from the National Central Registry of person accidents on the German railway network (STABAG). The association of daytime, weekday and month with the mean number of suicides was analysed applying linear regression. Potential differences by observation period were assessed by adding observation period and the respective interaction terms into the linear regression. A 95% confidence interval for the mean number of suicides was computed using the t distribution. A total of 7,187 railway suicides were recorded within both periods: 4,102 (57%) in the first period (1995-1998) and 3,085 (43%) in the second (2005-2008). The number of railway suicides was highest on Mondays and Tuesdays in the first period with an average of 3.2 and 3.5 events and of 2.6 events on both days in the second period. In both periods, railway suicides were more common between 6:00 am and noon, and between 6:00 pm and midnight. Seasonality was only prominent in the period 1995-1998. Over the course of two observation periods, the weekday and circadian patterns of railway suicides remained stable. Therefore, these patterns should be an integral part of railway suicide preventive measures, e.g. gatekeeper training courses.

  15. Two Positive Periodic Solutions for a Neutral Delay Model of Single-Species Population Growth with Harvesting

    OpenAIRE

    Fang, Hui

    2012-01-01

    By coincidence degree theory for k-set-contractive mapping, this paper establishes a new criterion for the existence of at least two positive periodic solutions for a neutral delay model of single-species population growth with harvesting. An example is given to illustrate the effectiveness of the result.

  16. Two Positive Periodic Solutions for a Neutral Delay Model of Single-Species Population Growth with Harvesting

    Directory of Open Access Journals (Sweden)

    Hui Fang

    2012-01-01

    Full Text Available By coincidence degree theory for k-set-contractive mapping, this paper establishes a new criterion for the existence of at least two positive periodic solutions for a neutral delay model of single-species population growth with harvesting. An example is given to illustrate the effectiveness of the result.

  17. Besicovitch almost periodic solutions for a class of second order differential equations involving reflection of the argument

    Directory of Open Access Journals (Sweden)

    Daxiong Piao

    2014-08-01

    Full Text Available In this paper, using the Fourier series expansion and fixed point methods, we investigate the existence and uniqueness of Besicovitch almost periodic solutions for a class of second order differential equations involving reflection of the argument. Lipschitz nonlinear case is considered.

  18. Global paths of time-periodic solutions of the Benjamin-Ono equation connecting arbitrary traveling waves

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose, David M.; Wilkening, Jon

    2008-12-11

    We classify all bifurcations from traveling waves to non-trivial time-periodic solutions of the Benjamin-Ono equation that are predicted by linearization. We use a spectrally accurate numerical continuation method to study several paths of non-trivial solutions beyond the realm of linear theory. These paths are found to either re-connect with a different traveling wave or to blow up. In the latter case, as the bifurcation parameter approaches a critical value, the amplitude of the initial condition grows without bound and the period approaches zero. We propose a conjecture that gives the mapping from one bifurcation to its counterpart on the other side of the path of non-trivial solutions. By experimentation with data fitting, we identify the form of the exact solutions on the path connecting two traveling waves, which represents the Fourier coefficients of the solution as power sums of a finite number of particle positions whose elementary symmetric functions execute simple orbits in the complex plane (circles or epicycles). We then solve a system of algebraic equations to express the unknown constants in the new representation in terms of the mean, a spatial phase, a temporal phase, four integers (enumerating the bifurcation at each end of the path) and one additional bifurcation parameter. We also find examples of interior bifurcations from these paths of already non-trivial solutions, but we do not attempt to analyze their algebraic structure.

  19. Stochastic periodic solution for a perturbed non-autonomous predator-prey model with generalized nonlinear harvesting and impulses

    Science.gov (United States)

    Zhang, Yan; Chen, Shihua; Gao, Shujing; Wei, Xiang

    2017-11-01

    In this paper, stochastic non-autonomous predator-prey models with and without impulses are investigated. The effects of generalized nonlinear harvesting for prey and predator populations are considered. For the stochastic system without impulses, the existence and uniqueness of the positive solution is proven and sufficient conditions that guarantee the extinction and persistence of the population in the mean are achieved. We show the existence of a nontrivial positive periodic solution by constructing appropriate Lyapunov functions and using Khasminskii's theory. Moreover, the global attractiveness and stochastic persistence in probability of the stochastic model are discussed. Results show that the stronger noises and nonlinear harvesting component can significantly influence the dynamics of the system and lead to the extinction of the predator population. Additionally, for the stochastic predator-prey system with impulsive effect, we prove that there exists a positive periodic solution. Numerical simulations are conducted to show the effectiveness and feasibility of the obtained results.

  20. Optimal Conditions for Maximum and Antimaximum Principles of the Periodic Solution Problem

    Directory of Open Access Journals (Sweden)

    Meirong Zhang

    2010-01-01

    Full Text Available Given a periodic, integrable potential q(t, we will study conditions on q(t so that the operator Lqx=x″+qx admits the maximum principle or the antimaximum principle with respect to the periodic boundary condition. By exploiting Green functions, eigenvalues, rotation numbers, and their estimates, we will give several optimal conditions.

  1. Log-stable laws as asymptotic solutions to a fragmentation equation:Application to the distribution of droplets in a high Weber-number spray

    Science.gov (United States)

    Rimbert, Nicolas; Séro-Guillaume, Olivier

    2004-05-01

    In this paper, it will be shown that “totally skewed to the left” log-stable distributions are suitable asymptotic solutions to a fragmentation equation. This result generalizes Kolmogorov’s work on log-normal distribution for the drops’ size number distribution of particles under pulverization. Indeed, Kolmogorov’s discrete process is extended to a continuous time Markov process for the volume distribution instead of the number distribution. New hypotheses are then introduced which lead to log-stable distributions as asymptotic solutions of the fragmentation equation. Log-stable laws are then used to fit experimental probability distribution function (pdf) of Simmons and Hanratty measuring drop sizes in a horizontal annular gas-liquid flow at high Weber number [Int. J. Multiphase Flow 27, 861 (2001)]. Log-stable pdf better fits to the experimental pdf than usual empirical spray pdf and especially, because of the heavy tail of the associated stable distribution, in the small drops part of the distribution.

  2. Meeting the Needs of Mothers During the Postpartum Period: Using Co-Creation Workshops to Find Technological Solutions.

    Science.gov (United States)

    Slomian, Justine; Emonts, Patrick; Vigneron, Lara; Acconcia, Alessandro; Reginster, Jean-Yves; Oumourgh, Mina; Bruyère, Olivier

    2017-05-03

    The postnatal period is associated with many new needs for mothers. The aim of this study was to find technological solutions that meet the needs of mothers during the year following childbirth. Two co-creation workshops were undertaken with parents and professionals. The aim of the first workshop was to create a list of all the criteria the proposed solution would have to address to meet the needs of mothers after childbirth. The aim of the second workshop was to create solutions in response to the criteria selected during the first workshop. Parents and health professionals want solutions that include empathy (ie, to help fight against the feelings of abnormality and loneliness), that help mothers in daily life, that are personalized and adapted to different situations, that are educational, and that assures some continuity in their contact with health professionals. In practice, we found that parents and professionals think the solution should be accessible to everyone and available at all times. To address these criteria, technology experts proposed different solutions, such as a forum dedicated to the postpartum period that is supervised by professionals, a centralized website, a system of videoconferencing, an online exchange group, a "gift voucher" system, a virtual reality app, or a companion robot. The human component seems to be very important during the postnatal period. Nevertheless, technology could be a great ally in helping mothers during the postpartum period. Technology can help reliably inform parents and may also give them the right tools to find supportive people. However, these technologies should be tested in clinical trials. ©Justine Slomian, Patrick Emonts, Lara Vigneron, Alessandro Acconcia, Jean-Yves Reginster, Mina Oumourgh, Olivier Bruyère. Originally published in JMIR Research Protocols (http://www.researchprotocols.org), 03.05.2017.

  3. Time-periodic solution of a 2D fourth-order nonlinear parabolic ...

    Indian Academy of Sciences (India)

    per( )), M1 = sup0≤t≤ω f (·,t) H1 . Then, there exists a solution (uNj (t))N j=1 ∈ C1 ω[0,ω] for problem (2.2), where. C1 ω[0,ω]={r(t)|r(t + ω) = r(t), ∀t ∈ R, r(t) ∈ C1[0,ω]}. In the meantime, the approximate solution uN (x,t) has the estimation sup. 0≤t≤ω. uN (·,t) 2. H1 ≤ c0(M1), where c0 is a positive constant independent of N ...

  4. Periodic Solutions of the Duffing Harmonic Oscillator by He's Energy Balance Method

    Directory of Open Access Journals (Sweden)

    A. M. El-Naggar

    2015-11-01

    Full Text Available Duffing harmonic oscillator is a common model for nonlinear phenomena in science and engineering. This paper presents He´s Energy Balance Method (EBM for solving nonlinear differential equations. Two strong nonlinear cases have been studied analytically. Analytical results of the EBM are compared with the solutions obtained by using He´s Frequency Amplitude Formulation (FAF and numerical solutions using Runge-Kutta method. The results show the presented method is potentially to solve high nonlinear oscillator equations.

  5. Stationary solution of the Rayleigh-Taylor instability for spatially periodic flows: questions of uniqueness, dimensionality, and universality

    International Nuclear Information System (INIS)

    Abarzhi, S.I.

    1996-01-01

    The stationary solutions of the Rayleigh-Taylor instability for spatially periodic flows with general symmetry are investigated here for the first time. The existence of a set of stationary solutions is established. The question of its dimensionality in function space is resolved on the basis of an analysis of the symmetry of the initial perturbation. The interrelationship between the dimensionality of the solution set and the symmetry of the flow is found. The dimensionality of the solution set is established for flows invariant with respect to one of five symmorphic two-dimensional groups. The nonuniversal character of the set of stationary solutions of the Rayleigh-Taylor instability is demonstrated. For flows in a tube, on the contrary, universality of the solution set, along with its independence of the symmetry of the initial perturbation, is assumed. The problem of the free boundary in the Rayleigh-Taylor instability is solved in the first two approximations, and their convergence is investigated. The dependence of the velocity and Fourier harmonics on the parameters of the problem is found. Possible symmetry violations of the flow are analyzed. Limits to previously studied cases are investigated, and their accuracy is established. Questions of the stability of the solutions obtained and the possibility of a physically correct statement of the problem are discussed

  6. Periodic solutions of Wick-type stochastic Korteweg–de Vries ...

    Indian Academy of Sciences (India)

    2016-09-20

    Sep 20, 2016 ... Keywords. Wick-type stochastic Korteweg–de Vries equation; Hermite transform; Kudrayshov method; white noise functionals. ... geneous balance and white noise analysis method, Xie. [14] obtained positonic solutions for ... method [16], homotopy perturbation method [17], F- expansion method [18] ...

  7. Periodic solutions of Wick-type stochastic Korteweg–de Vries ...

    Indian Academy of Sciences (India)

    2016-09-20

    Sep 20, 2016 ... illustrations in two- and three-dimensional plots of the obtained solutions depending on time and space are also given with white noise functionals. Keywords. Wick-type stochastic Korteweg–de Vries equation; Hermite transform; Kudrayshov method; white noise functionals. PACS Nos 02.30.lk; 02.30.Jr. 1.

  8. Periodic solutions of Wick-type stochastic Korteweg–de Vries ...

    Indian Academy of Sciences (India)

    Nonlinear stochastic partial differential equations have a wide range of applications in science and engineering. Finding exact solutions of the Wick-type stochastic equation will be helpful in the theories and numerical studies of such equations. In this paper, Kudrayshov method together with Hermite transform ...

  9. Existence and exponential stability of almost periodic solution for stochastic cellular neural networks with delay

    International Nuclear Information System (INIS)

    Huang Zaitang; Yang Qigui

    2009-01-01

    The paper considers the problems of existence of quadratic mean almost periodic and global exponential stability for stochastic cellular neural networks with delays. By employing the Holder's inequality and fixed points principle, we present some new criteria ensuring existence and uniqueness of a quadratic mean almost periodic and global exponential stability. These criteria are important in signal processing and the design of networks. Moreover, these criteria are also applied in others stochastic biological neural systems.

  10. Analytical determination of bifurcations of periodic solution in three-degree-of-freedom vibro-impact systems with clearance

    International Nuclear Information System (INIS)

    Liu, Yongbao; Wang, Qiang; Xu, Huidong

    2017-01-01

    The smooth bifurcation and non-smooth grazing bifurcation of periodic solution of three-degree-of-freedom vibro-impact systems with clearance are studied in this paper. Firstly, six-dimensional Poincaré maps are established through choosing suitable Poincaré section and solving periodic solutions of vibro-impact system. Then, as the analytic expressions of all eigenvalues of Jacobi matrix of six-dimensional map are unavailable, the numerical calculations to search for the critical bifurcation values point by point is a laborious job based on the classical critical criterion described by the properties of eigenvalues. To overcome the difficulty from the classical bifurcation criteria, the explicit critical criterion without using eigenvalues calculation of high-dimensional map is applied to determine bifurcation points of Co-dimension-one bifurcations and Co-dimension-two bifurcations, and then local dynamical behaviors of these bifurcations are further analyzed. Finally, the existence of the grazing periodic solution of the vibro-impact system and grazing bifurcation point are analyzed, the discontinuous grazing bifurcation behavior is studied based on the compound normal form map near the grazing point, the discontinuous jumping phenomenon and the co-existing multiple solutions near the grazing bifurcation point are revealed.

  11. Increase in HIV diagnoses among men who have sex with men in New Zealand from a stable low period.

    Science.gov (United States)

    Saxton, Peter J W; Dickson, Nigel P; McAllister, Susan M; Sharples, Katrina; Hughes, Anthony J

    2011-09-01

    To describe trends in HIV diagnoses among men who have sex with men (MSM) in New Zealand 1996-2008, and to identify characteristics associated with HIV diagnoses in the resurgent phase. Data collected through routine surveillance of HIV infection, where the mode of transmission included homosexual contact, were analysed over the period 1996-2008. Annual HIV diagnoses were low during 1996-2000, rose sharply between 2001 and 2005, and remained at an elevated plateau between 2006 and 2008. Over a quarter were attributed to HIV infection acquired overseas (28.6%). Trends in diagnoses of locally acquired HIV infection closely mirrored the trend of three diagnosis phases. Increases in locally acquired HIV occurred among virtually all characteristics of MSM. However, compared with MSM diagnosed in the low phase 1996-2000, individuals diagnosed in the resurgent phase 2001-05 were more likely to be aged 30-39, to have tested HIV-negative within the previous 2 years, to live in the Northern region encompassing Auckland, and to be of non-European ethnicity. The per capita HIV diagnosis rate among MSM was lowest in 1997, at 22.0 per million males aged 15-64, and highest in 2005 at 66.7 per million. The increase in HIV diagnoses among MSM in New Zealand was primarily due to an increase in locally acquired HIV infection, which disproportionately affected some groups of MSM. Factors driving this change in local epidemic conditions need to be identified. The rate of new HIV diagnoses among MSM remains low by international standards.

  12. A possible solution of the puzzling variation of the orbital period of MXB 1659-298

    Science.gov (United States)

    Iaria, R.; Gambino, A. F.; Di Salvo, T.; Burderi, L.; Matranga, M.; Riggio, A.; Sanna, A.; Scarano, F.; D'Aì, A.

    2018-01-01

    MXB 1659-298 is a transient neutron-star low-mass X-ray binary system that shows eclipses with a periodicity of 7.1 h. MXB 1659-298 went to outburst in 2015 August, after 14 years of quiescence. We investigate the orbital properties of this source with a baseline of 40 years, obtained by combining the eight eclipse arrival times present in the literature with 51 eclipse arrival times collected during the last two outbursts. A quadratic ephemeris does not fit the delays associated with the eclipse arrival times and the addition of a sinusoidal term with a period of 2.31 ± 0.02 yr is required. We infer a binary orbital period of P = 7.1161099(3) h and an orbital period derivative of \\dot{P}=-8.5(1.2) × 10^{-12} s s-1. We show that the large orbital period derivative can be explained with a highly non-conservative mass-transfer scenario, in which more than 98 per cent of the mass provided by the companion star leaves the binary system. We predict an orbital period derivative value of \\dot{P}=-6(3) × 10^{-12} s s-1 and constrain the companion-star mass between 0.3 and 1.2 M⊙. Assuming that the companion star is in thermal equilibrium, the periodic modulation can be due to either a gravitational quadrupole coupling arising from variations of the oblateness of the companion star or the presence of a third body of mass M3 > 21 Jovian masses.

  13. Positive Solutions of Three-Order Delayed Periodic Boundary Value Problems

    Directory of Open Access Journals (Sweden)

    Na Wang

    2017-01-01

    Full Text Available Our main purpose is to consider the existence of positive solutions for three-order two-point boundary value problem in the following form: u′′′(t+ρ3u(t=f(t,u(t-τ,  0≤t≤2π,  u(i(0=u(i(2π,  i=1,2,  u(t=σ,  -τ≤t≤0, where σ,ρ, and τ are given constants satisfying τ∈(0,π/2. Some inequality conditions on ρ3u-f(t,u guaranteeing the existence and nonexistence of positive solutions are presented. Our discussion is based on the fixed point theorem in cones.

  14. Slow time-periodic solutions of the Ginzburg-Landau equation

    NARCIS (Netherlands)

    Doelman, A.

    1989-01-01

    In this paper we study the behaviour of solutions of the form if(z, t) = q~(z) e- i~wt (e << 1) of the rescaled Ginzburg-Landau equation, ~k, = [ 1 - (1 + iB)l~kl2]~k + (1 + iA)~kzz, for A = ca, B = eb, w plays the role of free parameter. This leads to a perturbation analysis on a complex Duffing

  15. Exact periodic wave solutions to the coupled schrِodinger-KdV ...

    Indian Academy of Sciences (India)

    Solutions for the coupled non-linear partial differential equations. 2. Application. 2.1 The coupled Schriodinger-KdV equation. The coupled schriodinger-KdV equation iuط = uــ + uv, vط + 6vvـ + vـــ = (|u|2. ) ,. (8) describes various processes in dusty plasma, such as Langmuir, dust-acoustic wave and electromagnetic waves ...

  16. On lower bounds for possible blow-up solutions to the periodic Navier-Stokes equation

    International Nuclear Information System (INIS)

    Cortissoz, Jean C.; Montero, Julio A.; Pinilla, Carlos E.

    2014-01-01

    We show a new lower bound on the H .3/2 (T 3 ) norm of a possible blow-up solution to the Navier-Stokes equation, and also comment on the extension of this result to the whole space. This estimate can be seen as a natural limiting result for Leray's blow-up estimates in L p (R 3 ), 3 .5/2 (T 3 ), and give the corresponding extension to the case of the whole space

  17. Analysis of Periodic Orbits about the Triangular Solutions of the Restricted Sum-Jupiter and Earth-Moon Problem

    Directory of Open Access Journals (Sweden)

    Sang-Young Park

    1988-12-01

    Full Text Available Using the numerical solution in the plane restricted problem of three bodies, about 490 periodic orbits are computed numerically around the L5 of Sun-Jupiter and about 1600 periodic orbits also be done around the L5 of Earth-Moon system. As period increase, the energy and the shape of periodic orbits increase around the L5 of Sun-Jupiter system. But, in Earth-Moon system, the complex shapes and dents appear around the L5 and periodic orbits intersect one another in the place where dents are shown. And there is a region that three different periodic orbits exist with the same period in this region. The regions can exist around the L5 of Sun-Jupiter system where periodic orbit can be unstable by perturbation of other force besides the gravitational force of Jupiter. These regions which is close to L5 are a ~5.12 AU and a ~5.29 AU. The Trojan asteroids that have a small eccentricity and inclination can not exist in this region.

  18. On the Maximum Number of Periodical Solutions of a Class of Autonomous Systems

    International Nuclear Information System (INIS)

    Raeva, M.

    2008-01-01

    The autonomous systems are investigated on a certain condition, assuming the existence of inner resonances. Nonlinear parts are polynomials of a certain class. The present article is a continuation of the last one, which was published by American Institute of Physics, New York in 2007. We are interested both in the existence and the number of periodical trajectories of the system with initial conditions.

  19. Positive almost periodic solutions for a predator-prey Lotka-Volterra system with delays

    Directory of Open Access Journals (Sweden)

    Yuan Ye

    2012-08-01

    where $a_i,r_j, a_{il}, b_{ij},d_{jl},e_{jh}\\in C(\\mathbb{R},(0,\\infty\\sigma_{il},\\tau_{ij},\\delta_{jl},\\theta_{jh}\\in C(\\mathbb{R},\\mathbb{R}(i,l=1,\\ldots,n, j,h=1,\\ldots,m$ are almost periodic functions.

  20. Time-periodic solution of a 2D fourth-order nonlinear parabolic ...

    Indian Academy of Sciences (India)

    the classical existence theorem of global attractors, the authors proved that the equation possesses a global attractor in Hk (0 ≤ k < 5) space, which attracts any bounded subset of Hk( ) in the Hk. -norm. On the other hand, by using spectral method, Xu and Tang [16] studied eq. (1.1) with periodic boundary condition. In their ...

  1. On periodic bounded and unbounded solutions of second order nonlinear ordinary differential equations

    Czech Academy of Sciences Publication Activity Database

    Lomtatidze, Alexander

    2017-01-01

    Roč. 24, č. 2 (2017), s. 241-263 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : nonlinear ordinary differential equations * periodic boundary value problem * solvability Subject RIV: BA - General Mathematics Impact factor: 0.290, year: 2016 https://www.degruyter.com/view/j/gmj.2017.24.issue-2/gmj-2017-0009/gmj-2017-0009. xml

  2. Periodic solutions of a multi-DOF beam system with impact

    NARCIS (Netherlands)

    Vorst, E.L.B. van de; Campen, D.H. van; Kraker, A. de; Fey, R.H.B

    1996-01-01

    The steady state behaviour is analyzed of a periodically driven multi-DOF beam system which has an elastic stop at its middle. The elastic stop is modelled in a continuous way by using the contact law of Hertz. The beam is modelled by using finite elements and subsequently reduced by using a

  3. Periodic solutions of the Hamilton-Jacobi equation by the shooting method: A technique for beam dynamics

    International Nuclear Information System (INIS)

    Gabella, W.E.; Ruth, R.D.; Warnock, R.L.

    1988-05-01

    Periodic solutions of the Hamilton-Jacobi equation determine invariant tori in phase space. The Fourier spectrum of a torus with respect to angular coordinates gives useful information about nonlinear resonances and their potential for causing instabilities. We describe a method to solve the Hamilton-Jacobi equation for an arbitrary accelerator lattice. The method works with Fourier modes of the generating functions, and imposes periodicity in the machine azimuth by a shooting method. We give examples leading to three-dimensional plots in a surface of section. It is expected that the technique will be useful in lattice optimization. 14 refs., 6 figs., 1 tab

  4. Periodic solutions of the Hamilton-Jacobi equation by the shooting method: A technique for beam dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Gabella, W.E.; Ruth, R.D.; Warnock, R.L.

    1988-05-01

    Periodic solutions of the Hamilton-Jacobi equation determine invariant tori in phase space. The Fourier spectrum of a torus with respect to angular coordinates gives useful information about nonlinear resonances and their potential for causing instabilities. We describe a method to solve the Hamilton-Jacobi equation for an arbitrary accelerator lattice. The method works with Fourier modes of the generating functions, and imposes periodicity in the machine azimuth by a shooting method. We give examples leading to three-dimensional plots in a surface of section. It is expected that the technique will be useful in lattice optimization. 14 refs., 6 figs., 1 tab.

  5. Almost-Periodic Weak Solutions of Second-Order Neutral Delay-Differential Equations with Piecewise Constant Argument

    Directory of Open Access Journals (Sweden)

    Chuanyi Zhang

    2008-06-01

    Full Text Available We investigate the existence of almost-periodic weak solutions of second-order neutral delay-differential equations with piecewise constant argument of the form (x(t+x(t−1′′=qx(2[(t+1/2]+f(t, where [⋅] denotes the greatest integer function, q is a real nonzero constant, and f(t is almost periodic.

  6. Stability of small-amplitude periodic solutions near Hopf bifurcations in time-delayed fully-connected PLL networks

    Science.gov (United States)

    Ferruzzo Correa, Diego P.; Bueno, Átila M.; Castilho Piqueira, José R.

    2017-04-01

    In this paper we investigate stability conditions for small-amplitude periodic solutions emerging near symmetry-preserving Hopf bifurcations in a time-delayed fully-connected N-node PLL network. The study of this type of systems which includes the time delay between connections has attracted much attention among researchers mainly because the delayed coupling between nodes emerges almost naturally in mathematical modeling in many areas of science such as neurobiology, population dynamics, physiology and engineering. In a previous work it has been shown that symmetry breaking and symmetry preserving Hopf bifurcations can emerge in the parameter space. We analyze the stability along branches of periodic solutions near fully-synchronized Hopf bifurcations in the fixed-point space, based on the reduction of the infinite-dimensional space onto a two-dimensional center manifold in normal form. Numerical results are also presented in order to confirm our analytical results.

  7. A numerical model for the determination of periodic solutions of pipes subjected to non-conservative loads

    International Nuclear Information System (INIS)

    Velloso, P.A.; Galeao, A.C.

    1989-05-01

    This paper deals with nonlinear vibrations of pipes subjected to non-conservative loads. Periodic solutions of these problems are determined using a variational approach based on Hamilton's Principle combined with a Fourier series expansion to describe the displacement field time dependence. A finite element model which utilizes Hemite's cubic interpolation for both axial and transversal displacement amplitudes is used. This model is applied to the problem of a pipe subjected to a tangential and a normal follower force. The numerical results obtained with this model are compared with the corespondent solutions determined using a total lagrangian description for the Principle of Virtual Work, coupled with Newmark's step-by-step integration procedure. It is shown that for small to moderate displacement amplitudes the one-term Fourier series approximation compares fairly well with the predicted solution. For large displacements as least a two-term approximation should be utilized [pt

  8. On periodic bounded and unbounded solutions of second order nonlinear ordinary differential equations

    Czech Academy of Sciences Publication Activity Database

    Lomtatidze, Alexander

    2017-01-01

    Roč. 24, č. 2 (2017), s. 241-263 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : nonlinear ordinary differential equations * periodic boundary value problem * solvability Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 0.290, year: 2016 https://www.degruyter.com/view/j/gmj.2017.24.issue-2/gmj-2017-0009/gmj-2017-0009. xml

  9. Numerical doubly-periodic solution of the (2+1)-dimensional Boussinesq equation with initial conditions by the variational iteration method

    International Nuclear Information System (INIS)

    Inc, Mustafa

    2007-01-01

    In this Letter, a scheme is developed to study numerical doubly-periodic solutions of the (2+1)-dimensional Boussinesq equation with initial condition by the variational iteration method. As a result, the approximate and exact doubly-periodic solutions are obtained. For different modulus m, comparison between the approximate solution and the exact solution is made graphically, revealing that the variational iteration method is a powerful and effective tool to non-linear problems

  10. Abundant soliton and periodic wave solutions for the coupled Higgs field equation, the Maccari system and the Hirota-Maccari system

    Science.gov (United States)

    Wazwaz, Abdul-Majid

    2012-06-01

    In this work, we explore a variety of solitary wave ansatze and periodic wave ansatze to some nonlinear equations. Three complex systems of nonlinear equations that appear in mathematical physics are investigated. We derive abundant soliton and periodic wave solutions for the coupled Higgs field equation, the Maccari system and the Hirota-Maccari system. The results obtained show that these three coupled equations exhibit the richness of explicit solutions: solitons, periodic and rational wave solutions.

  11. Exact solutions to plaquette Ising models with free and periodic boundaries

    Directory of Open Access Journals (Sweden)

    Marco Mueller

    2017-01-01

    We clarify the exact relation between partition functions with free and periodic boundary conditions expressed in terms of original and product spin variables for the 2d plaquette and 3d fuki-nuke models, noting that the differences are already present in the 1d Ising model. In addition, we solve the 2d plaquette Ising model with helical boundary conditions. The various exactly solved examples illustrate how correlations can be induced in finite systems as a consequence of the choice of boundary conditions.

  12. The existence and regularity of time-periodic solutions to the three-dimensional Navier–Stokes equations in the whole space

    International Nuclear Information System (INIS)

    Kyed, Mads

    2014-01-01

    The existence, uniqueness and regularity of time-periodic solutions to the Navier–Stokes equations in the three-dimensional whole space are investigated. We consider the Navier–Stokes equations with a non-zero drift term corresponding to the physical model of a fluid flow around a body that moves with a non-zero constant velocity. The existence of a strong time-periodic solution is shown for small time-periodic data. It is further shown that this solution is unique in a large class of weak solutions that can be considered physically reasonable. Finally, we establish regularity properties for any strong solution regardless of its size. (paper)

  13. Field measurements of stable fly (Diptera: Muscidae) demography, fecundity, and survival based on daily trap catches at a beef farm in southern Ontario over a 5-yr period.

    Science.gov (United States)

    Beresford, D V; Sutcliffe, J F

    2012-11-01

    We sampled stable fly, Stomoxys calcitrans (L.), populations using a CO2 baited cloth trap (Nzi trap) each day throughout the summer and autumn at a beef farm near Peterborough, Ontario, Canada, from 1997 to 2001. Females (2,512) were dissected for ovarian age-grading, to produce a demographic profile of farm populations. The number of follicles were counted to produce fecundity estimates. The developmental periods of adult female stages, measured as accumulated degree-days above 10 degrees C, were determined for a lab colony of stable flies. These measurements were used to calculate survival in terms of degree-days of the farm populations each year. Of the 2,512 females caught, 42.4% were nulliparous on average each year. The median follicle size at insemination was 305 microm in the field populations, and 495 microm in the colony. Farm caught females had an average of 49.15 follicles per ovary overall, with the body size (leg length) and fecundity increasing slightly with age. On average, 44.5% (SE 3.2%) of nulliparous females survived to become parous, and of these, 45.7% (SE 2.1%) survived the uniparous state to become multiparous. Years of higher rainfall had increased fecundity; rainfall did not appear to affect survival.

  14. Fragment-Based Direct-Local-Ring-Coupled-Cluster Doubles Treatment Embedded in the Periodic Hartree-Fock Solution.

    Science.gov (United States)

    Masur, Oliver; Schütz, Martin; Maschio, Lorenzo; Usvyat, Denis

    2016-10-11

    We present a periodic/finite-cluster interface for fragment-based direct local ring-coupled-cluster doubles (d-LrCCD) calculations embedded in the periodic mean field. The fragment is defined by a set of Wannier functions (WFs), obtained from a periodic Hartree-Fock calculation. The pair-specific virtual space is spanned by projected atomic orbitals (PAOs) truncated to pair domains. The computational procedure is initiated by a periodic local Møller-Plesset (LMP2) calculation. A subset of the WF pairs is then subsequently subjected to a finite-cluster d-LrCCD treatment using the local coupled cluster program of Molpro; this subset is specified by an interorbital cutoff distance. The orbital, pair, and domain lists, as well as other essential quantities needed for d-LrCCD such as the Fock and overlap matrices, and the electron repulsion integrals (ERIs) in the basis of WFs and PAOs are evaluated in the periodic framework and passed to Molpro via an interface. These periodic quantities provide the correct periodic mean-field embedding for the fragment d-LrCCD. Moreover, no expensive orbital transformations involving orbital coefficients related to large supporting clusters are necessary. ERIs appearing in the d-LrCCD diagrams are factorized via density fitting, which enables an efficient processing of the corresponding terms via three-index intermediates. The corresponding 3-index and the metric 2-index ERIs involving auxiliary functions are also computed and transformed to the WF-PAO basis (the 3-index ERI) on the periodic side. Although the direct ring-CCD method itself is not generally more accurate than MP2, it is more stable in the case of small band gap systems, as it sums up the ring diagrams to infinite order. Furthermore, this interface is a first step toward a high-level fragment-based quantum chemical treatment such as local CCSD(T) within a periodic embedding that is treated at a lower level. As two test examples we study the physisorption of H 2 and

  15. Benefits of oral administration of an electrolyte solution interrupting a prolonged preoperatory fasting period in pediatric patients.

    Science.gov (United States)

    Moyao-García, D; Corrales-Fernández, M A; Blanco-Rodríguez, G; Sánchez-Hernández, E; Nava-Ocampo, A A

    2001-03-01

    The aim of this study was to evaluate the benefits of an oral isosmolar solution of electrolytes (ISE) administered to interrupt a prolonged fasting period in children undergoing an elective surgical procedure under general anesthesia. Forty unpremedicated children aged 3 to 12 years, ASA I, undergoing a surgical procedure requiring general anesthesia were assigned randomly to 1 of 2 groups. Group 1 consisted of patients with an overnight fasting period for milk and solids of at least 8 hours. In group 2, patients under a similar fasting period received a volume of 4 mL/kg of an oral ISE 3 hours before completing the fasting period. After anesthetic induction, blood glucose level (BGL) was quantified, and patients underwent an endoscopic examination to obtain the gastric content to determine the residual gastric volume (RGV) and pH levels. In group 1, the RGV was 0.78 +/- 0.44 mL/kg, pH was 1.75 +/- 0.38, and BGL was 86.4 +/- 14.5. In group 2, the RGV was 0.40 +/- 0.29 mL/kg, pH was 3.18 +/- 0.61, and BGL was 85.1 +/- 12.6. Only RGV and pH were significantly different between groups. A prolonged fasting period interrupted with oral ISE administration resulted in an RGV of low risk, without counterbalancing a potential fasting-induced hypoglycemia.

  16. Solution and stability of a set of P TH order linear differential equations with periodic coefficients via Chebyshev polynomials

    Directory of Open Access Journals (Sweden)

    Sinha S. C.

    1996-01-01

    Full Text Available Chebyshev polynomials are utilized to obtain solutions of a set of p th order linear differential equations with periodic coefficients. For this purpose, the operational matrix of differentiation associated with the shifted Chebyshev polynomials of the first kind is derived. Utilizing the properties of this matrix, the solution of a system of differential equations can be found by solving a set of linear algebraic equations without constructing the equivalent integral equations. The Floquet Transition Matrix (FTM can then be computed and its eigenvalues (Floquet multipliers subsequently analyzed for stability. Two straightforward methods, the ‘differential state space formulation’ and the ‘differential direct formulation’, are presented and the results are compared with those obtained from other available techniques. The well-known Mathieu equation and a higher order system are used as illustrative examples.

  17. Solution and stability of a set of PTH order linear differential equations with periodic coefficients via Chebyshev polynomials

    Directory of Open Access Journals (Sweden)

    S. C. Sinha

    1996-01-01

    Full Text Available Chebyshev polynomials are utilized to obtain solutions of a set of pth order linear differential equations with periodic coefficients. For this purpose, the operational matrix of differentiation associated with the shifted Chebyshev polynomials of the first kind is derived. Utilizing the properties of this matrix, the solution of a system of differential equations can be found by solving a set of linear algebraic equations without constructing the equivalent integral equations. The Floquet Transition Matrix (FTM can then be computed and its eigenvalues (Floquet multipliers subsequently analyzed for stability. Two straightforward methods, the ‘differential state space formulation’ and the ‘differential direct formulation’, are presented and the results are compared with those obtained from other available techniques. The well-known Mathieu equation and a higher order system are used as illustrative examples.

  18. Existence and Stability of the Periodic Solution with an Interior Transitional Layer in the Problem with a Weak Linear Advection

    Directory of Open Access Journals (Sweden)

    Nikolay N. Nefedov

    2018-01-01

    Full Text Available In the paper, we study a singularly perturbed periodic in time problem for the parabolic reaction-advection-diffusion equation with a weak linear advection. The case of the reactive term in the form of a cubic nonlinearity is considered. On the basis of already known results, a more general formulation of the problem is investigated, with weaker sufficient conditions for the existence of a solution with an internal transition layer to be provided than in previous studies. For convenience, the known results are given, which ensure the fulfillment of the existence theorem of the contrast structure. The justification for the existence of a solution with an internal transition layer is based on the use of an asymptotic method of differential inequalities based on the modification of the terms of the constructed asymptotic expansion. Further, sufficient conditions are established to fulfill these requirements, and they have simple and concise formulations in the form of the algebraic equation w(x0,t = 0 and the condition wx(x0,t < 0, which is essentially a condition of simplicity of the root x0(t and ensuring the stability of the solution found. The function w is a function of the known functions appearing in the reactive and advective terms of the original problem. The equation w(x0,t = 0 is a problem for finding the zero approximation x0(t to determine the localization region of the inner transition layer. In addition, the asymptotic Lyapunov stability of the found periodic solution is investigated, based on the application of the so-called compressible barrier method. The main result of the paper is formulated as a theorem. 

  19. Periodic Solutions and Homoclinic Bifurcations of Two Predator-Prey Systems with Nonmonotonic Functional Response and Impulsive Harvesting

    Directory of Open Access Journals (Sweden)

    Mingzhan Huang

    2014-01-01

    Full Text Available Two predator-prey models with nonmonotonic functional response and state-dependent impulsive harvesting are formulated and analyzed. By using the geometry theory of semicontinuous dynamic system, we obtain the existence, uniqueness, and stability of the periodic solution and analyse the dynamic phenomenon of homoclinic bifurcation of the first system by choosing the harvesting rate β as control parameter. Besides, we also study the homoclinic bifurcation of the second system about parameter δ on the basis of the theory of rotated vector field. Finally, numerical simulations are presented to illustrate the results.

  20. Existence and global exponential stability of periodic solutions for n-dimensional neutral dynamic equations on time scales.

    Science.gov (United States)

    Li, Bing; Li, Yongkun; Zhang, Xuemei

    2016-01-01

    In this paper, by using the existence of the exponential dichotomy of linear dynamic equations on time scales and the theory of calculus on time scales, we study the existence and global exponential stability of periodic solutions for a class of n-dimensional neutral dynamic equations on time scales. We also present an example to illustrate the feasibility of our results. The results of this paper are completely new and complementary to the previously known results even in both the case of differential equations (time scale [Formula: see text]) and the case of difference equations (time scale [Formula: see text]).

  1. Theory of hydrogen shell flashes on accreting white dwarfs. II. The stable shell burning and the recurrence period of shell flashes

    International Nuclear Information System (INIS)

    Fujimoto, M.Y.

    1982-01-01

    By means of analytical solutions of the envelope, thermal properties of hydrogen shell burning on accreting white dwarfs are studied and a general picture for their progress is presented which is described by two parameters, the accretion rate and the mass of the white dwarf. On a white dwarf, the thermal behavior of gas in the burning shell depends on the configuration of the envelope, which gives birth to two distinct types of stable configurations in thermal equilibrium, a high and a low state. In the high state, the nuclear shell burning makes up for the energy loss from the surface. There exists the lower limit to the envelope mass for this state. The nuclear burning rate lies in a narrow range of about a factor of 2.5, irrespective of the mass of the white dwarf, while the range itself varies greatly with the latter. In the low state, the nuclear burning is extinct, and yet the compressional heating by accreted gas balances with the cooling through the diffusion of heat. Therefore, the structure depends on the accretion rate. Thermal instability of nuclear burning sets the upper limit to the envelope mass of this state

  2. One-pot synthesis of stable colloidal solutions of MFe2O4 nanoparticles using oleylamine as solvent and stabilizer

    International Nuclear Information System (INIS)

    Pérez-Mirabet, Leonardo; Solano, Eduardo; Martínez-Julián, Fernando; Guzmán, Roger; Arbiol, Jordi; Puig, Teresa; Obradors, Xavier; Pomar, Alberto; Yáñez, Ramón; Ros, Josep; Ricart, Susagna

    2013-01-01

    Highlights: ► One-pot synthesis of ferrite magnetic nanoparticles ( 3 and M(acac) 2 (M = Co, Mn, Cu and Zn) in oleylamine, which also acts as a capping ligand, by producing stable colloidal dispersions of nanoparticles in non-polar solvents. The properties of the nanoparticles have been studied via different techniques, such as transmission electron microscopy, which shows that nanoparticles are monocrystallines and a narrow dispersion in size; magnetic analyses have demonstrated that the resulting ferrite nanoparticles show high saturation values and superparamagnetic behavior at room temperature; X-ray diffraction has also been performed, and it confirms that the synthesized nanoparticles have a spinel structure. Complementarily, ligand exchange has been also carried out in order to produce dispersions of the synthesized nanoparticles in polar media

  3. High Order A-stable Continuous General Linear Methods for Solution of Systems of Initial Value Problems in ODEs

    Directory of Open Access Journals (Sweden)

    Dauda GuliburYAKUBU

    2012-12-01

    Full Text Available Accurate solutions to initial value systems of ordinary differential equations may be approximated efficiently by Runge-Kutta methods or linear multistep methods. Each of these has limitations of one sort or another. In this paper we consider, as a middle ground, the derivation of continuous general linear methods for solution of stiff systems of initial value problems in ordinary differential equations. These methods are designed to combine the advantages of both Runge-Kutta and linear multistep methods. Particularly, methods possessing the property of A-stability are identified as promising methods within this large class of general linear methods. We show that the continuous general linear methods are self-starting and have more ability to solve the stiff systems of ordinary differential equations, than the discrete ones. The initial value systems of ordinary differential equations are solved, for instance, without looking for any other method to start the integration process. This desirable feature of the proposed approach leads to obtaining very high accuracy of the solution of the given problem. Illustrative examples are given to demonstrate the novelty and reliability of the methods.

  4. Controls of evaporative irrigation return flows in comparison to seawater intrusion in coastal karstic aquifers in northern Sri Lanka: Evidence from solutes and stable isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Chandrajith, Rohana, E-mail: rohanac@pdn.ac.lk [Department of Geology, Faculty of Science, University of Peradeniya (Sri Lanka); Diyabalanage, Saranga [Department of Geology, Faculty of Science, University of Peradeniya (Sri Lanka); Premathilake, K.M. [Water Supply and Drainage Board, Telewala Road, Ratmalana (Sri Lanka); Hanke, Christian; Geldern, Robert van; Barth, Johannes A.C. [Friedrich-Alexander University Erlangen-Nuremberg (FAU), Department of Geography and Geosciences, GeoZentrum Nordbayern, Schlossgarten 5, 91054 Erlangen (Germany)

    2016-04-01

    Groundwater in Miocene karstic aquifers in the Jaffna Peninsula of Sri Lanka is an important resource since no other fresh water sources are available in the region. The subsurface is characterized by highly productive limestone aquifers that are used for drinking and agriculture purposes. A comprehensive hydrogeochemical study was carried out to reveal the processes affecting the groundwater quality in this region. Major and trace element composition and environmental isotope ratios of oxygen and hydrogen (δ{sup 18}O{sub H2O} and δ{sup 2}H{sub H2O}) were determined in 35 groundwater samples for this investigation. The ion abundance of groundwater in the region was characterized by an anion sequence order with HCO{sub 3}¯ > Cl¯ > SO{sub 4}¯ > NO{sub 3}¯. For cations, average Na{sup +}+K{sup +} contents in groundwater exceeded those of Ca{sup 2+} + Mg{sup 2+} in most cases. Ionic relationships of major solutes indicated open system calcite dissolution while seawater intrusions are also evident but only close to the coast. The solute contents are enriched by agricultural irrigation returns and associated evaporation. This was confirmed by the stable isotope composition of groundwater that deviated from the local meteoric water line (LMWL) and formed its own regression line denoted as the local evaporation line (LEL). The latter can be described by δ{sup 2}H{sub H2O} = 5.8 × δ{sup 18}O{sub H2O-–} 2.9. Increased contents of nitrate-N (up to 5 mg/L), sulfate (up to 430 mg/L) and fluoride (up to 1.5 mg/L) provided evidences for anthropogenic inputs of solutes, most likely from agriculture activities. Among trace elements Ba, Sr, As and Se levels in the Jaffna groundwater were higher compared to that of the dry zone metamorphic aquifers in Sri Lanka. Solute geochemistry and stable isotope evidences from the region indicates that groundwater in the area is mainly derived from local modern precipitation but modified heavily by progressive evaporative

  5. A Jacobi–Legendre polynomial-based method for the stable solution of a deconvolution problem of the Abel integral equation type

    International Nuclear Information System (INIS)

    Ammari, Amara; Karoui, Abderrazek

    2012-01-01

    In this paper, we build a stable scheme for the solution of a deconvolution problem of the Abel integral equation type. This scheme is obtained by further developing the orthogonal polynomial-based techniques for solving the Abel integral equation of Ammari and Karoui (2010 Inverse Problems 26 105005). More precisely, this method is based on the simultaneous use of the two families of orthogonal polynomials of the Legendre and Jacobi types. In particular, we provide an explicit formula for the computation of the Legendre expansion coefficients of the solution. This explicit formula is based on some known formulae for the exact computation of the integrals of the product of some Jacobi polynomials with the derivatives of the Legendre polynomials. Besides the explicit and the exact computation of the expansion coefficients of the solution, our proposed method has the advantage of ensuring the stability of the solution under a fairly weak condition on the functional space to which the data function belongs. Finally, we provide the reader with some numerical examples that illustrate the results of this work. (paper)

  6. Functional Aspects of the Solution Structure and Dynamics of PAF, a Highly Stable Antifungal Protein from Penicillium chrysogenum

    Science.gov (United States)

    Batta, Gyula; Barna, Teréz; Gáspári, Zoltán; Sándor, Szabolcs; Kövér, Katalin E.; Binder, Ulrike; Sarg, Bettina; Kaiserer, Lydia; Chhillar, Anil Kumar; Eigentler, Andrea; Leiter, Éva; Hegedüs, Nikoletta; Pócsi, István; Lindner, Herbert; Marx, Florentine

    2015-01-01

    Summary PAF is a promising antimycotic without toxic effects on mammalian cells and therefore may be a drug candidate against the often lethal Aspergillus infections in human. The pathogenesis of PAF on sensitive fungi involves G-protein coupled signaling followed by apoptosis. Here, the solution structure of this small, cationic, antifungal protein from Penicillium chrysogenum is determined by solution NMR. We proved that PAF belongs to the SCOP fold class of its closest homologue AFP from Aspergillus giganteus. PAF comprises five β—strands forming two orthogonally packed β—sheets sharing a common interface. The ambiguity in the assignment of two disulfide bonds of three was investigated by NMR dynamics combined with restrained molecular dynamics calculations. The clue could not be resolved: two ensembles with different disulfide patterns and the one with no S-S bond exhibit essentially the same fold. 15N relaxation dispersion and interference experiments did not reveal disulfide bond rearrangements via slow exchange. The measured order parameters and the 3.0 ns correlation time is appropriate for a compact monomeric protein of this size. We demonstrated by site-directed mutagenesis that the highly conserved and positively charged lysine-rich domain region on the surface enhances the toxicity of PAF. However, the efficacy of the OB fold is reduced in PAF compared to AFP, due to less solvent exposed aromatic regions explaining the absence of chitobiose binding. The present work lends further support to the understanding of the documented substantial differences between the mode of action of two highly homologous antifungal proteins. PMID:19459942

  7. Existence and Uniqueness of Positive Periodic Solutions for a Delayed Predator-Prey Model with Dispersion and Impulses

    Directory of Open Access Journals (Sweden)

    Zhenguo Luo

    2014-01-01

    Full Text Available An impulsive Lotka-Volterra type predator-prey model with prey dispersal in two-patch environments and time delays is investigated, where we assume the model of patches with a barrier only as far as the prey population is concerned, whereas the predator population has no barriers between patches. By applying the continuation theorem of coincidence degree theory and by means of a suitable Lyapunov functional, a set of easily verifiable sufficient conditions are obtained to guarantee the existence, uniqueness, and global stability of positive periodic solutions of the system. Some known results subject to the underlying systems without impulses are improved and generalized. As an application, we also give two examples to illustrate the feasibility of our main results.

  8. Validation of classical density-dependent solute transport theory for stable, high-concentration-gradient brine displacements in coarse and medium sands

    Science.gov (United States)

    Watson, S. J.; Barry, D. A.; Schotting, R. J.; Hassanizadeh, S. M.

    A series of careful laboratory soil column experiments was carried out for the purpose of providing data for testing recently presented theories of miscible density-dependent flow and transport. In particular, modifications to the standard theory involve extensions to both Darcy's (for flow) and Fick's laws (for diffusive/dispersive solute flux). Both coarse- and medium-grained sands were used in the experiments. All experiments concerned upward (i.e., stable) displacement of fresh water within the soil by a brine solution, under either constant head or constant volume flux conditions. The experimental data were analysed using accurate numerical solutions of the standard governing flow and transport model, as well as models with modified Darcy's and Fick's laws. Model parameters were determined by a step-wise fitting procedure based on the least-squares criterion. The results show clearly that, for large density contrasts, an extended Darcy's law was not necessary. On the other hand, an extension to Fick's Law was needed to model the experimental data accurately.

  9. Effect of the Addition of a Labile Gelatin Component on the Degradation and Solute Release Kinetics of a Stable PEG Hydrogel

    Science.gov (United States)

    Waldeck, H.; Kao, W. J.

    2013-01-01

    Characterization of the degradation mechanisms and resulting products of biodegradable materials is critical in understanding the behavior of the material including solute transport and biological response. Previous mathematical analyses of a semi-interpenetrating network (sIPN) containing both labile gelatin and a stable cross-linked poly(ethylene glycol) (PEG) network found that diffusion-based models alone were unable to explain the release kinetics of solutes from the system. In this study, degradation of the sIPN and its effect on solute release and swelling kinetics were investigated. The kinetics of the primary mode of degradation, gelatin dissolution, was dependent on temperature, preparation methods, PEGdA and gelatin concentration, and the weight ratio between the gelatin and PEG. The gelatin dissolution rate positively correlated with both matrix swelling and the release kinetics of high-molecular-weight model compound, FITC-dextran. Coupled with previous in vitro studies, the kinetics of sIPN degradation provided insights into the time-dependent changes in cellular response including adhesion and protein expression. These results provide a facile guide in material formulation to control the delivery of high-molecular-weight compounds with concomitant modulation of cellular behavior. PMID:21801489

  10. Light curve solutions and study of roles of magnetic fields in period variations of the UV Leo system

    Directory of Open Access Journals (Sweden)

    D Manzoori

    2009-12-01

    Full Text Available The solutions of photometric BV light curves for the Algol like system UV Leo were obtained using Wilson-Devinney code. The physical and orbital parameters along with absolute dimensions of the system were determined. It has been found that to best fit the V light curve of the system, assumptions of three dark spots were necessary two on the secondary and one on the primary. The absolute visual magnitudes (Mv of the individual components i.e., primary and secondary were estimated to 4.41 and 4.43, respectively, through the color curve analysis. The period analysis of the system presented elsewhere, indicated a cyclic period change of 12 yr duration, which was attributed to magnetic activity cycle, as a main cause of period variation in the system, through the Applegate mechanism. To verify the Applegate model I preformed calculations of some related parameters barrowed from Apllegate and Kalimeris. Values of all the calculated parameters were in accordance to those obtained for similar systems by Applegate. The differential magnitudes Δ B and Δ V, along with corresponding values of Δ(B-V color index. The cyclic variations in brightness are quite clear. There are three predictions of Applegate's theory concerning effects of cyclic magnetic changes on the period variations, which can be checked through the observations, these are as follows: I The long term variations in mean brightness (at outside of eclipses and cyclic changes of orbital period, vary with the same period. II The active star gets bluer as it gets brightened and/or the brightness and color variations are to be in phase. III Changes in luminosity due to changes in quadrupole moment should be of the order 0.1 mag. All the above mentioned predictions of Applegate’s theory are verified. These results combined with cyclic character of P(E presented elsewhere and also consistency of parameters which are obtained in this paper, led me to conclude that one the main causes of period

  11. Closed-Form and Numerically-Stable Solutions to Problems Related to the Optimal Two-Impulse Transfer Between Specified Terminal States of Keplerian Orbits

    Science.gov (United States)

    Senent, Juan

    2011-01-01

    The first part of the paper presents some closed-form solutions to the optimal two-impulse transfer between fixed position and velocity vectors on Keplerian orbits when some constraints are imposed on the magnitude of the initial and final impulses. Additionally, a numerically-stable gradient-free algorithm with guaranteed convergence is presented for the minimum delta-v two-impulse transfer. In the second part of the paper, cooperative bargaining theory is used to solve some two-impulse transfer problems when the initial and final impulses are carried by different vehicles or when the goal is to minimize the delta-v and the time-of-flight at the same time.

  12. Frequency-Stable Ionic-Type Hybrid Gate Dielectrics for High Mobility Solution-Processed Metal-Oxide Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Jae Sang Heo

    2017-06-01

    Full Text Available In this paper, we demonstrate high mobility solution-processed metal-oxide thin-film transistors (TFTs by using a high-frequency-stable ionic-type hybrid gate dielectric (HGD. The HGD gate dielectric, a blend of sol-gel aluminum oxide (AlOx and poly(4-vinylphenol (PVP, exhibited high dielectric constant (ε~8.15 and high-frequency-stable characteristics (1 MHz. Using the ionic-type HGD as a gate dielectric layer, an minimal electron-double-layer (EDL can be formed at the gate dielectric/InOx interface, enhancing the field-effect mobility of the TFTs. Particularly, using the ionic-type HGD gate dielectrics annealed at 350 °C, InOx TFTs having an average field-effect mobility of 16.1 cm2/Vs were achieved (maximum mobility of 24 cm2/Vs. Furthermore, the ionic-type HGD gate dielectrics can be processed at a low temperature of 150 °C, which may enable their applications in low-thermal-budget plastic and elastomeric substrates. In addition, we systematically studied the operational stability of the InOx TFTs using the HGD gate dielectric, and it was observed that the HGD gate dielectric effectively suppressed the negative threshold voltage shift during the negative-illumination-bias stress possibly owing to the recombination of hole carriers injected in the gate dielectric with the negatively charged ionic species in the HGD gate dielectric.

  13. Temperature variability at Dürres Maar, Germany during the Migration Period and at High Medieval Times, inferred from stable carbon isotopes of Sphagnum cellulose

    Directory of Open Access Journals (Sweden)

    A. Lücke

    2011-09-01

    Full Text Available This paper presents a high resolution reconstruction of local growing season temperature (GST anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (δ13Ccellulose separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum δ13Ccellulose/temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period, marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times, the amplitude in the reconstructed temperature variability is most likely overestimated; nevertheless, above-average temperatures are obvious during this time span, which are followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similarly warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring datasets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical datasets. Most notably, e.g., during the Early Middle Ages and at High Medieval Times, temperatures were neither low nor high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are

  14. Envelope periodic solutions for a discrete network with the Jacobi elliptic functions and the alternative (G'/G)-expansion method including the generalized Riccati equation

    Science.gov (United States)

    Tala-Tebue, E.; Tsobgni-Fozap, D. C.; Kenfack-Jiotsa, A.; Kofane, T. C.

    2014-06-01

    Using the Jacobi elliptic functions and the alternative ( G'/ G-expansion method including the generalized Riccati equation, we derive exact soliton solutions for a discrete nonlinear electrical transmission line in (2+1) dimension. More precisely, these methods are general as they lead us to diverse solutions that have not been previously obtained for the nonlinear electrical transmission lines. This study seeks to show that it is not often necessary to transform the equation of the network into a well-known differential equation before finding its solutions. The solutions obtained by the current methods are generalized periodic solutions of nonlinear equations. The shape of solutions can be well controlled by adjusting the parameters of the network. These exact solutions may have significant applications in telecommunication systems where solitons are used to codify or for the transmission of data.

  15. Adsorption of BTX (benzene, toluene, o-xylene, and p-xylene) from aqueous solutions by modified periodic mesoporous organosilica.

    Science.gov (United States)

    Moura, Cícero P; Vidal, Carla B; Barros, Allen L; Costa, Luelc S; Vasconcellos, Luiz C G; Dias, Francisco S; Nascimento, Ronaldo F

    2011-11-15

    The capacity of a periodic mesoporous organosilica (PMO) to adsorb the aromatic compounds benzene, toluene, o-, and p-xylenes (BTX), which are usually present in produced waters, was investigated under both column and batch processes. The PMO was synthesized by condensation of 1,4 bis(triethoxisilyl)benzene (BTEB) under acidic conditions by using structure-directing agent (SDA) Pluronic P123 in the presence of KCl. Thermogravimetric analysis showed that the presence of the surfactant decreases the thermal stability of the PMO. The small-angle X-ray diffraction pattern, as well as the nitrogen adsorption/desorption isotherm measurements, revealed that the synthesized material has a crystalline structure, with hexagonally-ordered cylindrical mesopores. The adsorption kinetics study indicated an adsorption equilibrium time of 50 min and also showed that the data best fitted the pseudo-first order kinetic model. The intraparticle diffusion model was also tested and pointed to the occurrence of such process in all cases. Both Langmuir and Temkin models best represented the adsorption isotherms of toluene; Langmuir and Redlich-Peterson models best represented the data obtained for the other compounds. Adsorption capacity decreases in the order benzene>o-xylene>p-xylene>toluene. Satisfactory results were observed in the application of the synthesized PMO for the removal of BTX from aqueous solution. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Periodic mean-field solutions and the spectra of discrete bosonic fields: Trace formula for Bose-Hubbard models

    Science.gov (United States)

    Engl, Thomas; Urbina, Juan Diego; Richter, Klaus

    2015-12-01

    We consider the many-body spectra of interacting bosonic quantum fields on a lattice in the semiclassical limit of large particle number N . We show that the many-body density of states can be expressed as a coherent sum over oscillating long-wavelength contributions given by periodic, nonperturbative solutions of the, typically nonlinear, wave equation of the classical (mean-field) limit. To this end, we construct the semiclassical approximation for both the smooth and oscillatory parts of the many-body density of states in terms of a trace formula starting from the exact path integral form of the propagator between many-body quadrature states. We therefore avoid the use of a complexified classical limit characteristic of the coherent state representation. While quantum effects such as vacuum fluctuations and gauge invariance are exactly accounted for, our semiclassical approach captures quantum interference and therefore is valid well beyond the Ehrenfest time where naive quantum-classical correspondence breaks down. Remarkably, due to a special feature of harmonic systems with incommensurable frequencies, our formulas are generically valid also in the free-field case of noninteracting bosons.

  17. THE EXISTENCE OF THE STABILIZING SOLUTION OF THE RICCATI EQUATION ARISING IN DISCRETE-TIME STOCHASTIC ZERO SUM LQ DYNAMIC GAMES WITH PERIODIC COEFFICIENTS

    Directory of Open Access Journals (Sweden)

    Vasile Dr ̆agan

    2017-06-01

    Full Text Available We investigate the problem for solving a discrete-time periodic gen- eralized Riccati equation with an indefinite sign of the quadratic term. A necessary condition for the existence of bounded and stabilizing solution of the discrete-time Riccati equation with an indefinite quadratic term is derived. The stabilizing solution is positive semidefinite and satisfies the introduced sign conditions. The proposed condition is illustrated via a numerical example.

  18. Solution-Processed Cu(In, Ga)(S, Se)2Nanocrystal as Inorganic Hole-Transporting Material for Efficient and Stable Perovskite Solar Cells.

    Science.gov (United States)

    Xu, Lu; Deng, Lin-Long; Cao, Jing; Wang, Xin; Chen, Wei-Yi; Jiang, Zhiyuan

    2017-12-01

    Perovskite solar cells are emerging as one of the most promising candidates for solar energy harvesting. To date, most of the high-performance perovskite solar cells have exclusively employed organic hole-transporting materials (HTMs) such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) or polytriarylamine (PTAA) which are often expensive and have low hole mobility. Almost all these HTMs reported needed lithium salt, e.g., lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI) doping, to improve hole mobility and performance. However, the use of Li-TFSI should be avoided because the hygroscopic nature of Li-TFSI could cause decomposition of perovskite and reduce device stability. Herein, we employed solution-processed CuIn 0.1 Ga 0.9 (S 0.9 Se 0.1 ) 2 (CIGSSe) nanocrystals as a novel inorganic HTM in perovskite solar cells. A power conversion efficiency of 9.15% was obtained for CIGSSe-based devices with improved stability, compared to devices using spiro-OMeTAD as HTM. This work offers a promising candidate of Cu-based inorganic HTM for efficient and stable perovskite solar cells.

  19. Facile and efficient one-pot solvothermal and microwave-assisted synthesis of stable colloidal solutions of MFe{sub 2}O{sub 4} spinel magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Solano, Eduardo; Perez-Mirabet, Leonardo [Universitat Autonoma de Barcelona, Departament de Quimica (Spain); Martinez-Julian, Fernando; Guzman, Roger; Arbiol, Jordi; Puig, Teresa; Obradors, Xavier [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC (Spain); Yanez, Ramon [Universitat Autonoma de Barcelona, Departament de Quimica (Spain); Pomar, Alberto; Ricart, Susagna, E-mail: ricart@icmab.es [Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC (Spain); Ros, Josep [Universitat Autonoma de Barcelona, Departament de Quimica (Spain)

    2012-08-15

    Well-defined synthesis conditions of high quality MFe{sub 2}O{sub 4} (M = Mn, Fe, Co, Ni, Zn, and Cu) spinel ferrite magnetic nanoparticles, with diameters below 10 nm, have been described based on facile and efficient one-pot solvothermal or microwave-assisted heating procedures. Both methods are reproducible and scalable and allow forming concentrated stable colloidal solutions in polar solvents, but microwave-assisted heating allows reducing 15 times the required annealing time and leads to an enhanced monodispersity of the nanoparticles. Non-agglomerated nanoparticles dispersions have been achieved using a simple one-pot approach where a single compound, triethyleneglycol, behaves at the same time as solvent and capping ligand. A narrow nanoparticle size distribution and high quality crystallinity have been achieved through selected nucleation and growth conditions. High resolution transmission electron microscopy images and electron energy loss spectroscopy analysis confirm the expected structure and composition and show that similar crystal faceting has been formed in both synthetic approaches. The spinel nanoparticles behave as ferrimagnets with a high saturation magnetization and are superparamagnetic at room temperature. The influence of synthesis route on phase purity and unconventional magnetic properties is discussed in some particular cases such as CuFe{sub 2}O{sub 4}, CoFe{sub 2}O{sub 4}, and ZnFe{sub 2}O{sub 4}.

  20. Synergetic effects of solution-processable fluorinated graphene and PEDOT as a hole-transporting layer for highly efficient and stable normal-structure perovskite solar cells.

    Science.gov (United States)

    Yu, Jae-Hun; Lee, Cheol-Ho; Joh, Han-Ik; Yeo, Jun-Seok; Na, Seok-In

    2017-11-16

    We demonstrate that a bi-interlayer consisting of water-free poly(3,4-ethylenedioxythiophene) (PEDOT) and fluorinated reduced graphene oxide (FrGO) noticeably enhances the efficiency and the stability of the normal-structure perovskite solar cells (PeSCs). With simple and low temperature solution-processing, the PeSC employing the PEDOT + FrGO interlayer exhibits a significantly improved power conversion efficiency (PCE) of 14.9%. Comprehensive investigations indicate that the enhanced PCE is mostly attributed to the retarded recombination in the devices. The minimized recombination phenomena are related to the interfacial dipoles at the PEDOT/FrGO interface, which facilitates the electron-blocking and the higher built-in potential in the devices. Furthermore, the PEDOT + FrGO device shows a better stability by maintaining 70% of the initial PCE over the 30 days exposure to ambient conditions. This is because the more hydrophobic graphitic sheets of the FrGO on the PEDOT further protect the perovskite films from oxygen/water penetration. Consequently, the introduction of composite interfacial layers including graphene derivatives can be an effective and versatile strategy for high-performing, stable, and cost-effective PeSCs.

  1. Facile and efficient one-pot solvothermal and microwave-assisted synthesis of stable colloidal solutions of MFe2O4 spinel magnetic nanoparticles

    International Nuclear Information System (INIS)

    Solano, Eduardo; Perez-Mirabet, Leonardo; Martinez-Julian, Fernando; Guzmán, Roger; Arbiol, Jordi; Puig, Teresa; Obradors, Xavier; Yañez, Ramón; Pomar, Alberto; Ricart, Susagna; Ros, Josep

    2012-01-01

    Well-defined synthesis conditions of high quality MFe 2 O 4 (M = Mn, Fe, Co, Ni, Zn, and Cu) spinel ferrite magnetic nanoparticles, with diameters below 10 nm, have been described based on facile and efficient one-pot solvothermal or microwave-assisted heating procedures. Both methods are reproducible and scalable and allow forming concentrated stable colloidal solutions in polar solvents, but microwave-assisted heating allows reducing 15 times the required annealing time and leads to an enhanced monodispersity of the nanoparticles. Non-agglomerated nanoparticles dispersions have been achieved using a simple one-pot approach where a single compound, triethyleneglycol, behaves at the same time as solvent and capping ligand. A narrow nanoparticle size distribution and high quality crystallinity have been achieved through selected nucleation and growth conditions. High resolution transmission electron microscopy images and electron energy loss spectroscopy analysis confirm the expected structure and composition and show that similar crystal faceting has been formed in both synthetic approaches. The spinel nanoparticles behave as ferrimagnets with a high saturation magnetization and are superparamagnetic at room temperature. The influence of synthesis route on phase purity and unconventional magnetic properties is discussed in some particular cases such as CuFe 2 O 4 , CoFe 2 O 4 , and ZnFe 2 O 4 .

  2. SOLUTIONING

    Directory of Open Access Journals (Sweden)

    Maria de Hoyos Guajardo, Ph.D. Candidate, M.Sc., B.Eng.

    2004-11-01

    Full Text Available The theory that is presented below aims to conceptualise how a group of undergraduate students tackle non-routine mathematical problems during a problem-solving course. The aim of the course is to allow students to experience mathematics as a creative process and to reflect on their own experience. During the course, students are required to produce a written ‘rubric’ of their work, i.e., to document their thoughts as they occur as well as their emotionsduring the process. These ‘rubrics’ were used as the main source of data.Students’ problem-solving processes can be explained as a three-stage process that has been called ‘solutioning’. This process is presented in the six sections below. The first three refer to a common area of concern that can be called‘generating knowledge’. In this way, generating knowledge also includes issues related to ‘key ideas’ and ‘gaining understanding’. The third and the fourth sections refer to ‘generating’ and ‘validating a solution’, respectively. Finally, once solutions are generated and validated, students usually try to improve them further before presenting them as final results. Thus, the last section deals with‘improving a solution’. Although not all students go through all of the stages, it may be said that ‘solutioning’ considers students’ main concerns as they tackle non-routine mathematical problems.

  3. Stable beams

    CERN Multimedia

    2015-01-01

    Stable beams: two simple words that carry so much meaning at CERN. When LHC page one switched from "squeeze" to "stable beams" at 10.40 a.m. on Wednesday, 3 June, it triggered scenes of jubilation in control rooms around the CERN sites, as the LHC experiments started to record physics data for the first time in 27 months. This is what CERN is here for, and it’s great to be back in business after such a long period of preparation for the next stage in the LHC adventure.   I’ve said it before, but I’ll say it again. This was a great achievement, and testimony to the hard and dedicated work of so many people in the global CERN community. I could start to list the teams that have contributed, but that would be a mistake. Instead, I’d simply like to say that an achievement as impressive as running the LHC – a machine of superlatives in every respect – takes the combined effort and enthusiasm of everyone ...

  4. Structure of solutions sets and a continuous version of Filippov's theorem for first order impulsive differential inclusions with periodic conditions

    Directory of Open Access Journals (Sweden)

    John Graef

    2009-04-01

    where $J=[0,b]$ and $F: J\\times \\mathbb{R}^n\\to{\\cal P}(\\mathbb{R}^n$ is a set-valued map. The functions $I_k$ characterize the jump of the solutions at impulse points $t_k$ ($k=1, 2, \\ldots,m$. The topological structure of solution sets as well as some of their geometric properties (contractibility and $R_\\delta$-sets are studied. A continuous version of Filippov's theorem is also proved.

  5. Instabilities in fluid layers and in reaction-diffusion systems: Steady states, time-periodic solutions, non-periodic attractors, and related convective and otherwise non-linear phenomena

    International Nuclear Information System (INIS)

    Garcia Velarde, M.

    1977-01-01

    Thermo convective instabilities in horizontal fluid layers are discussed with emphasis on the Rayleigh-Bernard model problem. Steady solutions and time-dependent phenomena (relaxation oscillations and transition to turbulence) are studied within the nonlinear Boussinesq-Oberbeck approximation. Homogeneous steady solutions, limit cycles, and inhomogeneous (ordered) spatial structures are also studied in simple reaction-diffusion systems. Lastly, the non-periodic attractor that appears at large Rayleigh numbers in the truncated Boussinesq-Oberbeck model of Lorenz, is constructed, and a discussion of turbulent behavior is given. (Author) 105 refs

  6. Instabilities in fluid layers and in reaction-diffusion systems: Steady states, time-periodic solutions, non-periodic attractors, and related convective and otherwise non-linear phenomena

    International Nuclear Information System (INIS)

    Garcia Velarde, M.

    1977-01-01

    Thermoconvective instabilities in horizontal fluid layers are discussed with emphasis on the Rayleigh-Benard model problem. Steady solutions and time-dependent phenomena (relaxation oscillations and transition to turbulence) are studied within the nonlinear Boussinesq-Oberbeck approximation. Homogeneous steady solutions, limit cycles, and inhomogeneous (ordered) spatial structures are also studied in simple reaction-diffusion systems. Lastly, the non-periodic attractor that appears at large Rayleigh numbers in the truncated Boussinesq-Oberbeck model of Lorenz, is constructed, and a discussion of turbulent behavior is given. (author) [es

  7. Instabilities in fluid layers and in reaction-diffusion systems: Steady states, time-periodic solutions, non-periodic attractors, and related convective and otherwise non-linear phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Velarde, M.

    1977-07-01

    Thermo convective instabilities in horizontal fluid layers are discussed with emphasis on the Rayleigh-Bernard model problem. Steady solutions and time-dependent phenomena (relaxation oscillations and transition to turbulence) are studied within the nonlinear Boussinesq-Oberbeck approximation. Homogeneous steady solutions, limit cycles, and inhomogeneous (ordered) spatial structures are also studied in simple reaction-diffusion systems. Lastly, the non-periodic attractor that appears at large Rayleigh numbers in the truncated Boussinesq-Oberbeck model of Lorenz, is constructed, and a discussion of turbulent behavior is given. (Author) 105 refs.

  8. Differences in delta13C and delta15N stable isotopes in the pearly razorfish Xyrichtys novacula related to the sex, location and spawning period.

    Science.gov (United States)

    Box, A; Deudero, S; Blanco, A; Grau, A M; Riera, F

    2010-06-01

    In the present study, Xyrichtys novacula (Labridae) were sampled at five locations around the islands of Ibiza and Formentera (western Mediterranean Sea). Isotopic signatures of delta13C, delta15N and the C:N ratio were analysed in relation to locality, sex and size differences. delta13C and delta15N partitioning was also studied in the reproductive spawning period. There were significant differences in the delta13C signature between localities for both sexes, but not for delta15N. Sex differences were also found with a mean +/-s.e. value of -17.38 +/- 0.06 per thousand delta13C and 8.36 +/- 0.05 per thousand delta(15)N for females and -17.17 +/- 0.07 per thousand delta13C and 8.80 +/- 0.06 per thousand delta15N for males. Increasing total length in both sexes was positively correlated with delta15N enrichment and a significant positive linear regression was established for both variables. During the reproductive spawning period, there were changes in delta13C fractioning with enrichment in postspawning females and males (with respect to prespawning and spawning periods) and delta(15)N impoverishment in postspawning females (with respect to prespawning and spawning periods). Xyrichtys novacula uses local food sources, as confirmed by delta(13)C and delta(15)N, and females and males use different food sources, thus avoiding intraspecific competition. This was confirmed by delta15N enrichment as size increased. Spawning leads to special requirements for gonad maturation, which is reflected in the isotopic signatures for both sexes.

  9. Periodic nanostructures imprinted on high-temperature stable sol–gel films by ultraviolet-based nanoimprint lithography for photovoltaic and photonic applications

    Energy Technology Data Exchange (ETDEWEB)

    Back, Franziska [Schott AG, Research and Technology Development, Hattenbergstraße 10, 55122 Mainz (Germany); Fraunhofer-Institut für Silicatforschung ISC, Neunerplatz 2, 97082 Würzburg (Germany); Bockmeyer, Matthias; Rudigier-Voigt, Eveline [Schott AG, Research and Technology Development, Hattenbergstraße 10, 55122 Mainz (Germany); Löbmann, Peer [Fraunhofer-Institut für Silicatforschung ISC, Neunerplatz 2, 97082 Würzburg (Germany)

    2014-07-01

    Nanostructured sol–gel films with high-temperature stability are used in the area of electronics, photonics or biomimetic materials as light-trapping architectures in solar cells, displays, waveguides or as superhydrophobic surfaces with a lotus effect. In this work, high-temperature stable 2-μm nanostructured surfaces were prepared by ultraviolet-based nanoimprint lithography using an alkoxysilane binder incorporating modified silica nanoparticles. Material densification during thermal curing and microstructural evolution which are destined for a high structural fidelity of nanostructured films were investigated in relation to precursor chemistry, particle morphology and particle content of the imprint resist. The mechanism for densification and shrinkage of the films was clarified and correlated with the structural fidelity to explain the influence of the geometrical design on the optical properties. A high internal coherence of the microstructure of the nanostructured films results in a critical film thickness of > 5 μm. The structured glassy layers with high inorganic content show thermal stability up to 800 °C and have a high structural fidelity > 90% with an axial shrinkage of 16% and a horizontal shrinkage of 1%. This material allows the realization of highly effective light-trapping architectures for polycrystalline silicon thin-film solar cells on glass but also for the preparation of 2D photonic crystals for telecommunication wavelengths. - Highlights: • Fundamental research • Hybrid sol–gel material with high-temperature stability and contour accuracy • Ensuring of cost-efficient and industrially feasible processing • Application in photonic and photovoltaic.

  10. Growth increment periodicity in the shell of the razor clam Ensis directus using stable isotopes as a method to validate age

    Directory of Open Access Journals (Sweden)

    J. F. M. F. Cardoso

    2013-07-01

    Full Text Available To evaluate the role of the razor clam Ensis directus in Dutch coastal waters, understanding its population dynamics is important. As such, the age structure of the population forms a key parameter. Accurate age determination in bivalve shells is not always straightforward due to the difficulty of interpreting externally visible growth lines. In the present paper, we aimed at validating the seasonality in growth line formation using visual techniques in combination with stable oxygen and carbon isotope analyses (δ18O and δ13C. High δ18O values in the shell coincided with growth marks on the external surface of the valve and in acetate peels of the shell's cross section. Most shell δ18O samples were assigned to the months from June to September. From November to March no samples were retrieved, indicating that the shell did not grow. The lowest reconstructed temperature (6.3 °C suggests that ~ 6 °C may be the threshold temperature for growth. Nevertheless, most of the reconstructed values fell above 14.5 °C, indicating that growth occurred mainly in the summer at relatively high temperatures. Shell δ13C profiles followed a more or less seasonal cycle, but no direct relationship could be made between δ13C values and annual growth lines. Although counting external annual growth lines led to a correct estimation of age and consequently of growth rates, we recommend analysing acetate peels of cross sections to support the distinction between annual lines and disturbance lines.

  11. Analyses of stable isotopes in camelids collagen bones from Tulan Ravine, Atacama Puna, early formative period (CA 3,1000-2,400BP)

    International Nuclear Information System (INIS)

    Lopez, Patricio; Cartajena, Isabel; Nunez, Lautaro

    2013-01-01

    This paper presents the results of isotope analysis (δ 13 C y δ 15 N) conducted on bone collagen found in Lama guanicoe and Lama glama remains from Tulan-85 and Tulan-54 archaeological sites. Both sites have been dated to the Early Formative Period (ca. 3,100-2,400 ap) and are located southeast of the Atacama Puna basin. Faunal samples were selected using anatomical and morphometric criteria. The results indicate divergences in the diets of both species, reflecting vegetation variation in the Tulan Quebrada caused by altitude differences and linked to hunting and herding areas [es

  12. On a second order of accuracy stable difference scheme for the solution of a source identification problem for hyperbolic-parabolic equations

    Science.gov (United States)

    Ashyralyyeva, Maral; Ashyraliyev, Maksat

    2016-08-01

    In the present paper, a second order of accuracy difference scheme for the approximate solution of a source identification problem for hyperbolic-parabolic equations is constructed. Theorem on stability estimates for the solution of this difference scheme and their first and second order difference derivatives is presented. In applications, this abstract result permits us to obtain the stability estimates for the solutions of difference schemes for approximate solutions of two source identification problems for hyperbolic-parabolic equations.

  13. On the existence of positive periodic solutions for totally nonlinear neutral differential equations of the second-order with functional delay

    Directory of Open Access Journals (Sweden)

    Emmanuel K. Essel

    2014-01-01

    Full Text Available We prove that the totally nonlinear second-order neutral differential equation \\[\\frac{d^2}{dt^2}x(t+p(t\\frac{d}{dt}x(t+q(th(x(t\\] \\[=\\frac{d}{dt}c(t,x(t-\\tau(t+f(t,\\rho(x(t,g(x(t-\\tau(t\\] has positive periodic solutions by employing the Krasnoselskii-Burton hybrid fixed point theorem.

  14. GENETIC ALGORITHM SOLUTION FOR MULTI-PERIOD TWO-ECHELON INTEGRATED COMPETITIVE/UNCOMPETITIVE FACILITY LOCATION PROBLEM

    OpenAIRE

    XUE-FENG WANG; XIAO-MING SUN; YANG FANG

    2008-01-01

    This paper addresses the multi-period two-echelon integrated competitive/uncompetitive facility location problem in a distribution system design that involves locating regional distribution centers (RDCs) and stores, and determining the best strategy for distributing the commodities from a central distribution center (CDC) to RDCs and from RDCs to stores. The goal is to determine the optimal numbers, locations and capacities of RDCs and stores so as to maximize the total profit of the distrib...

  15. Numerical solution of the Maxwell-Vlasov equations in the periodic regime. Application to the study of isotope separation by ion cyclotron resonance

    International Nuclear Information System (INIS)

    Omnes, P.

    1999-01-01

    This work is dedicated to the study of the behaviour of a magnetic confined plasma that is excited by a purely sinusoidal electric current delivered by an antenna. The response of the electrons to the electromagnetic field is considered as linear, whereas the ions of the plasma are represented by a non-relativistic Vlasov equation. In order to avoid transients, the coupled Maxwell-Vlasov equations are solved in a periodic mode and in a bounded domain. An equivalent electric conductivity tensor has been defined, this tensor is a linear operator that links the electric current generated by the movement of the particles to the electromagnetic field. Theoretical considerations can assure the existence and uniqueness of a periodical solution to Vlasov equations and of a solution to Maxwell equations in harmonic mode. The system of equations is periodical and has been solved by using an iterative method. The application of this method to the simulation of a isotopic separation device based on ionic cyclotron resonance has shown that the convergence is reached in a few iterations and that the solution is valid. Furthermore a method based on a finite-volume formulation of Maxwell equations in the time domain is presented. 2 new variables are defined in order to better take into account the Gauss' law and the conservation of the magnetic flux, the new system is still hyperbolic. The parallelization of the process has been successfully realized. (A.C.)

  16. Stable isotopes

    International Nuclear Information System (INIS)

    Evans, D.K.

    1986-01-01

    Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

  17. Categorisation of northern California rainfall for periods with and without a radar brightband using stable isotopes and a novel automated precipitation collector†

    Directory of Open Access Journals (Sweden)

    Tyler B. Coplen

    2015-12-01

    Full Text Available During landfall of extratropical cyclones between 2005 and 2011, nearly 1400 precipitation samples were collected at intervals of 30-min time resolution with novel automated collectors at four NOAA sites in northern California [Alta (ATA, Bodega Bay (BBY, Cazadero (CZD and Shasta Dam (STD] during 43 events. Substantial decreases were commonly followed hours later by substantial increases in hydrogen isotopic composition (δ 2HVSMOW where VSMOW is Vienna Standard Mean Ocean Water and oxygen isotopic composition (δ 18OVSMOW of precipitation. These variations likely occur as pre-cold frontal precipitation generation transitions from marine vapour masses having low rainout to cold cloud layers having much higher rainout (with concomitant brightband signatures measured by an S-band profiling radar and lower δ 2HVSMOW values of precipitation, and finally to shallower, warmer precipitating clouds having lower rainout (with non-brightband signatures and higher δ 2HVSMOW values of precipitation, in accord with ‘seeder–feeder’ precipitation. Of 82 intervals identified, a remarkable 100.5 ‰ decrease in δ 2HVSMOW value was observed for a 21 January 2010 event at BBY. Of the 61 intervals identified with increases in δ 2HVSMOW values as precipitation transitioned to shallower, warmer clouds having substantially less rainout (the feeder part of the seeder–feeder mechanism, a remarkable increase in δ 2HVSMOW value of precipitation of 82.3 ‰ was observed for a 10 February 2007 event at CZD. All CZD and ATA events having δ 2HVSMOW values of precipitation below −105 ‰ were atmospheric rivers (ARs, and of the 13 events having δ 2HVSMOW values of precipitation below −80 ‰, 77 % were ARs. Cloud echo-top heights (a proxy for atmospheric temperature were available for 23 events. The mean echo-top height is greater for higher rainout periods than that for lower rainout periods in 22 of the 23 events. The lowest δ 2HVSMOW of precipitation of

  18. Pastoralism in Northern Peru during Pre-Hispanic Times: Insights from the Mochica Period (100–800 AD) Based on Stable Isotopic Analysis of Domestic Camelids

    Science.gov (United States)

    Dufour, Elise; Goepfert, Nicolas; Gutiérrez Léon, Belkys; Chauchat, Claude; Franco Jordán, Régulo; Sánchez, Segundo Vásquez

    2014-01-01

    Llama (Lama glama) and alpaca (Vicugna pacos) are the only large domesticated animals indigenous to the Americas. Pastoralism occupies a fundamental economic, social and religious role in Andean life. Today, camelid livestock are confined to the ecozone of the puna (above 3,500 masl), while their presence on the Pacific coast during pre-Hispanic times is attested by archaeological skeletal remains. This study aims to document herding practices on the northern Peruvian coast during the Early Intermediate Period (200 BC-600 AD) by gaining insights into diet, location of breeding and mobility of archaeological camelids from the funerary and ritual contexts of two Mochica sites, Uhle Platform in Huacas de Moche and El Brujo. The three first early years and the long-term life histories of the animals were documented by the combined bulk analysis of bone collagen (δ13Ccol and δ15Ncol) and bone structural carbonate (δ13Cbone and δ18Obone) and the serial analysis of structural carbonate of molar tooth enamel (δ13Cenamel and δ18Oenamel). Mochica camelids were bred in the low and/or middle valleys, unlike their modern counterparts, who are restricted to highland puna C3 pastures. Archaeological camelids had diverse and complex life histories, usually with substantial maize foddering. An ontogenetic switch in diet and possible residential mobility during the course of life were identified for some specimens. Although the inference of geographic origin from δ18Obone and δ18Oenamel values was limited because of the lack of understanding of the influence of environmental and biological factors, tooth enamel analysis has great potential for exploring camelid herding practices and Andean pastoralism. Our study suggested that Mochica herders adapted their practices to the difficult lowland environment and that herding practices were varied and not restricted to breeding at higher altitudes. The role of maize in different aspects of the economic life of the Mochicas is also

  19. Pastoralism in northern Peru during pre-Hispanic times: insights from the Mochica Period (100-800 AD) based on stable isotopic analysis of domestic camelids.

    Science.gov (United States)

    Dufour, Elise; Goepfert, Nicolas; Gutiérrez Léon, Belkys; Chauchat, Claude; Jordán, Régulo Franco; Vásquez Sánchez, Segundo

    2014-01-01

    Llama (Lama glama) and alpaca (Vicugna pacos) are the only large domesticated animals indigenous to the Americas. Pastoralism occupies a fundamental economic, social and religious role in Andean life. Today, camelid livestock are confined to the ecozone of the puna (above 3,500 masl), while their presence on the Pacific coast during pre-Hispanic times is attested by archaeological skeletal remains. This study aims to document herding practices on the northern Peruvian coast during the Early Intermediate Period (200 BC-600 AD) by gaining insights into diet, location of breeding and mobility of archaeological camelids from the funerary and ritual contexts of two Mochica sites, Uhle Platform in Huacas de Moche and El Brujo. The three first early years and the long-term life histories of the animals were documented by the combined bulk analysis of bone collagen (δ(13)C col and δ(15)N col) and bone structural carbonate (δ(13)C bone and δ(18)O bone) and the serial analysis of structural carbonate of molar tooth enamel (δ(13)C enamel and δ(18)O enamel). Mochica camelids were bred in the low and/or middle valleys, unlike their modern counterparts, who are restricted to highland puna C3 pastures. Archaeological camelids had diverse and complex life histories, usually with substantial maize foddering. An ontogenetic switch in diet and possible residential mobility during the course of life were identified for some specimens. Although the inference of geographic origin from δ(18)O bone and δ(18)O enamel values was limited because of the lack of understanding of the influence of environmental and biological factors, tooth enamel analysis has great potential for exploring camelid herding practices and Andean pastoralism. Our study suggested that Mochica herders adapted their practices to the difficult lowland environment and that herding practices were varied and not restricted to breeding at higher altitudes. The role of maize in different aspects of the economic life

  20. Periodic protein adsorption at the gold/biotin aqueous solution interface: evidence of kinetics with time delay

    Science.gov (United States)

    Neff, H.; Laborde, H. M.; Lima, A. M. N.

    2016-11-01

    An oscillatory molecular adsorption pattern of the protein neutravidin from aqueous solution onto gold, in presence of a pre-deposited self assembled mono-molecular biotin film, is reported. Real time surface Plasmon resonance sensing was utilized for evaluation of the adsorption kinetics. Two different fractions were identified: in the initial phase, protein molecules attach irreversibly onto the Biotin ligands beneath towards the jamming limit, forming a neutravidin-biotin fraction. Afterwards, the growth rate exhibits distinct, albeit damped adsorption-desorption oscillations over an extended time span, assigned to a quasi reversibly bound fraction. These findings agree with, and firstly confirm a previously published model, proposing macro-molecular adsorption with time delay. The non-linear dynamic model is applicable to and also resembles non-damped oscillatory binding features of the hetero-catalytic oxidation of carbon monoxide molecules on platinum in the gas phase. An associated surface residence time can be linked to the dynamics and time scale required for self-organization.

  1. In-soil radon anomalies as precursors of earthquakes: a case study in the SE slope of Mt. Etna in a period of quite stable weather conditions

    International Nuclear Information System (INIS)

    Vizzini, Fabio; Brai, Maria

    2012-01-01

    In-soil radon concentrations as well as climatic parameters (temperature, atmospheric pressure and relative humidity) were collected in St. Venerina (Eastern Sicily – Italy) from March 19th to May 22nd 2009, close to an active fault system called Timpe Fault System (TFS), which is strictly linked to the geodynamics of Mt. Etna. During the monitoring period no drastic climatic variations were observed and, on the other hand, important seismic events were recorded close to the monitoring site. A seismic swarm composed of 5 earthquakes was observed in the Milo area on March 25th (M max = 2.7) at just 5.1 km from the site, and on May 13th an earthquake of 3.6 magnitude was recorded in the territory of St. Venerina, at just 3.2 km from the site; the earthquake was felt by the population and reported by all local and regional media. The in-soil radon concentrations have shown anomalous increases possibly linked to the earthquakes recorded, but certainly not attributable to local meteorology. To verify this assumption the average radon concentration and the standard deviation (σ) have been calculated and the regions of ±1.5σ and ±2σ deviation from the average concentration have been investigated. Moreover, to further minimise the contribution of the meteorological parameters on the in-soil radon fluctuations, a multiple regressions method has been used. To distinguish those earthquakes which could generate in-soil radon anomalies as precursors, the Dobrovolsky radius has been applied. The results obtained suggests that a clear correlation between earthquakes and in-soil radon increases exist, and that the detection of the in-soil radon anomalies becomes surely simpler in particular favourable conditions: weather stability, earthquakes within the Dobrovolsky radius and close to the monitoring area. Moreover, the absence of large variations of the climatic parameters, which could generate incoherent noise components to the radon signal, has made the radon

  2. In-soil radon anomalies as precursors of earthquakes: a case study in the SE slope of Mt. Etna in a period of quite stable weather conditions.

    Science.gov (United States)

    Vizzini, Fabio; Brai, Maria

    2012-11-01

    In-soil radon concentrations as well as climatic parameters (temperature, atmospheric pressure and relative humidity) were collected in St. Venerina (Eastern Sicily - Italy) from March 19th to May 22nd 2009, close to an active fault system called Timpe Fault System (TFS), which is strictly linked to the geodynamics of Mt. Etna. During the monitoring period no drastic climatic variations were observed and, on the other hand, important seismic events were recorded close to the monitoring site. A seismic swarm composed of 5 earthquakes was observed in the Milo area on March 25th (M(max) = 2.7) at just 5.1 km from the site, and on May 13th an earthquake of 3.6 magnitude was recorded in the territory of St. Venerina, at just 3.2 km from the site; the earthquake was felt by the population and reported by all local and regional media. The in-soil radon concentrations have shown anomalous increases possibly linked to the earthquakes recorded, but certainly not attributable to local meteorology. To verify this assumption the average radon concentration and the standard deviation (σ) have been calculated and the regions of ±1.5σ and ±2σ deviation from the average concentration have been investigated. Moreover, to further minimise the contribution of the meteorological parameters on the in-soil radon fluctuations, a multiple regressions method has been used. To distinguish those earthquakes which could generate in-soil radon anomalies as precursors, the Dobrovolsky radius has been applied. The results obtained suggests that a clear correlation between earthquakes and in-soil radon increases exist, and that the detection of the in-soil radon anomalies becomes surely simpler in particular favourable conditions: weather stability, earthquakes within the Dobrovolsky radius and close to the monitoring area. Moreover, the absence of large variations of the climatic parameters, which could generate incoherent noise components to the radon signal, has made the radon fluctuations

  3. Pastoralism in northern Peru during pre-Hispanic times: insights from the Mochica Period (100-800 AD based on stable isotopic analysis of domestic camelids.

    Directory of Open Access Journals (Sweden)

    Elise Dufour

    Full Text Available Llama (Lama glama and alpaca (Vicugna pacos are the only large domesticated animals indigenous to the Americas. Pastoralism occupies a fundamental economic, social and religious role in Andean life. Today, camelid livestock are confined to the ecozone of the puna (above 3,500 masl, while their presence on the Pacific coast during pre-Hispanic times is attested by archaeological skeletal remains. This study aims to document herding practices on the northern Peruvian coast during the Early Intermediate Period (200 BC-600 AD by gaining insights into diet, location of breeding and mobility of archaeological camelids from the funerary and ritual contexts of two Mochica sites, Uhle Platform in Huacas de Moche and El Brujo. The three first early years and the long-term life histories of the animals were documented by the combined bulk analysis of bone collagen (δ(13C col and δ(15N col and bone structural carbonate (δ(13C bone and δ(18O bone and the serial analysis of structural carbonate of molar tooth enamel (δ(13C enamel and δ(18O enamel. Mochica camelids were bred in the low and/or middle valleys, unlike their modern counterparts, who are restricted to highland puna C3 pastures. Archaeological camelids had diverse and complex life histories, usually with substantial maize foddering. An ontogenetic switch in diet and possible residential mobility during the course of life were identified for some specimens. Although the inference of geographic origin from δ(18O bone and δ(18O enamel values was limited because of the lack of understanding of the influence of environmental and biological factors, tooth enamel analysis has great potential for exploring camelid herding practices and Andean pastoralism. Our study suggested that Mochica herders adapted their practices to the difficult lowland environment and that herding practices were varied and not restricted to breeding at higher altitudes. The role of maize in different aspects of the economic

  4. Low-coverage surface diffusion in complex periodic energy landscapes. II. Analytical solution for systems with asymmetric hops

    Science.gov (United States)

    Gosálvez, Miguel A.; Otrokov, Mikhail M.; Ferrando, Nestor; Ryabishchenkova, Anastasia G.; Ayuela, Andres; Echenique, Pedro M.; Chulkov, Evgueni V.

    2016-05-01

    This is part II in a series of two papers that introduce a general expression for the tracer diffusivity in complex, periodic energy landscapes with M distinct hop rates in one-, two-, and three-dimensional diluted systems (low coverage, single-tracer limit). While Part I [Gosálvez et al., Phys. Rev. B 93, 075429 (2016), 10.1103/PhysRevB.93.075429] focuses on the analysis of diffusion in systems where the end sites of the hops are located symmetrically with respect to the hop origins (symmetric hops), as encountered in many ideal surfaces and bulk materials, this report (Part II) presents a more general approach to determining the tracer diffusivity in systems where the end sites can be located asymmetrically with respect to the hop origins (asymmetric hops), as observed in reconstructed and/or chemically modified surfaces and/or bulk materials. The obtained diffusivity formulas for numerous systems are validated against kinetic Monte Carlo simulations and previously reported analytical expressions based on the continuous-time random walk (CTRW) method. The proposed method corrects some of the CTRW formulas and provides new expressions for difficult cases that have not been solved earlier. This demonstrates the ability of the proposed formalism to describe tracer diffusion.

  5. Periodic Control of Power Electronic Converters

    DEFF Research Database (Denmark)

    Zhou, Keliang; Danwei, Wang; Yang, Yongheng

    Advanced power electronic converters convert, control and condition electricity. Power converters require control strategies for periodic signal compensation to assure good power quality and stable power system operation. This comprehensive text presents the most recent internal model principle...... based periodic control technology, which offers the perfect periodic control solution for power electronic conversion. It also provides complete analysis and synthesis methods for periodic control systems, and plenty of practical examples to demonstrate the validity of proposed periodic control...... technology for power converters. It proposes a unified framework for housing periodic control schemes for power converters, and provides a general proportional-integral-derivative control solution to periodic signal compensation in extensive engineering applications. Periodic Control of Power Electronic...

  6. Stability of Periodically Focused Intense Particle Beams

    International Nuclear Information System (INIS)

    Pakter, R.; Rizzato, F. B.

    2001-01-01

    A stability analysis of periodically focused intense particle beams based on the beam envelope equation is performed. We show that (i) the scenario, as the focusing field increases, is not the existence of a single threshold above which stable matched (equilibrium) solutions are absent, as generally believed, but the existence of successive regions of stability interrupted by gaps of instability; (ii) the beam can be focused to tighter radii using new stable matched solutions found for focusing field strengths greater than the previous threshold. Self-consistent simulations validate the findings

  7. Stable exponential cosmological solutions with zero variation of G and three different Hubble-like parameters in the Einstein-Gauss-Bonnet model with a Λ-term

    Energy Technology Data Exchange (ETDEWEB)

    Ernazarov, K.K. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); Ivashchuk, V.D. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); VNIIMS, Center for Gravitation and Fundamental Metrology, Moscow (Russian Federation)

    2017-06-15

    We consider a D-dimensional gravitational model with a Gauss-Bonnet term and the cosmological term Λ. We restrict the metrics to diagonal cosmological ones and find for certain Λ a class of solutions with exponential time dependence of three scale factors, governed by three non-coinciding Hubble-like parameters H > 0, h{sub 1} and h{sub 2}, corresponding to factor spaces of dimensions m > 2, k{sub 1} > 1 and k{sub 2} > 1, respectively, with k{sub 1} ≠ k{sub 2} and D = 1 + m + k{sub 1} + k{sub 2}. Any of these solutions describes an exponential expansion of 3d subspace with Hubble parameter H and zero variation of the effective gravitational constant G. We prove the stability of these solutions in a class of cosmological solutions with diagonal metrics. (orig.)

  8. Stable exponential cosmological solutions with zero variation of G in the Einstein-Gauss-Bonnet model with a Λ-term

    Energy Technology Data Exchange (ETDEWEB)

    Ernazarov, K.K. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); Ivashchuk, V.D. [RUDN University, Institute of Gravitation and Cosmology, Moscow (Russian Federation); Center for Gravitation and Fundamental Metrology, VNIIMS, Moscow (Russian Federation)

    2017-02-15

    A D-dimensional gravitational model with a Gauss-Bonnet term and the cosmological term Λ is considered. By assuming diagonal cosmological metrics, we find, for a certain fine-tuned Λ, a class of solutions with exponential time dependence of two scale factors, governed by two Hubble-like parameters H > 0 and h < 0, corresponding to factor spaces of dimensions m > 3 and l > 1, respectively, with (m,l) ≠ (6,6), (7,4), (9,3) and D = 1+m+l. Any of these solutions describes an exponential expansion of three-dimensional subspace with Hubble parameter H and zero variation of the effective gravitational constant G. We prove the stability of these solutions in a class of cosmological solutions with diagonal metrics. (orig.)

  9. High-Performance Solution-Processable Poly(p-phenylene vinylene)s for Air-Stable Organic Field-Effect Transistors

    NARCIS (Netherlands)

    Breemen, Albert J.J.M. van; Herwig, Peter T.; Chlon, Ceciel H.T.; Sweelssen, Jörgen; Schoo, Herman F.M.; Benito, Estrella Mena; Leeuw, Dago M. de; Tanase, Christina; Wildeman, Jurjen; Blom, Paul W.M.

    2005-01-01

    The influence of the substitution pattern (unsymmetrical or symmetrical), the nature of the side chain (linear or branched), and the processing of several solution processable alkoxy-substituted poly(p-phenylene vinylene)s (PPVs) on the charge-carrier mobility in organic field-effect transistors

  10. 14-1: Large-Area Processing of Solution Type Metal-Oxide in TFT Backplanes and Integration in Highly Stable OLED Displays

    NARCIS (Netherlands)

    Marinkovic, M.; Takata, R.; Neumann, A.; Pham, D.V.; Anselmann, R.; Maas, J.; Steen, J.L. van der; Gelinck, G.; Ilias Katsouras

    2017-01-01

    Solution type metal-oxide semiconductor was processed on mass-production ready equipment and integrated in a backplane with ESL architecture TFTs. Excellent thickness uniformity of the semiconductor layer was obtained over the complete Gen1 glass substrate (320 mm x 352 mm), resulting in homogeneous

  11. Origins of Highly Stable Al-evaporated Solution-processed ZnO Thin Film Transistors: Insights from Low Frequency and Random Telegraph Signal Noise

    Science.gov (United States)

    Kim, Joo Hyung; Kang, Tae Sung; Yang, Jung Yup; Hong, Jin Pyo

    2015-01-01

    One long-standing goal in the emerging field of flexible and transparent electronic devices is to meet the demand of key markets, such as enhanced output performance for metal oxide semiconductor thin film transistors (TFTs) prepared by a solution process. While solution-based fabrication techniques are cost-effective and ensure large-area coverage at low temperature, their utilization has the disadvantage of introducing large trap states into TFTs. Such states, the formation of which is induced by intrinsic defects initially produced during preparation, have a significant impact on electrical performance. Therefore, the ability to enhance the electrical characteristics of solution-processed TFTs, along with attaining a firm understanding of their physical nature, remains a key step towards extending their use. In this study, measurements of low-frequency noise and random telegraph signal noise are employed as generic alternative tools to examine the origins of enhanced output performance for solution-processed ZnO TFTs through the control of defect sites by Al evaporation. PMID:26525284

  12. Thermo-solutal and kinetic modes of stable dendritic growth with different symmetries of crystalline anisotropy in the presence of convection

    Science.gov (United States)

    Alexandrov, Dmitri V.; Galenko, Peter K.; Toropova, Lyubov V.

    2018-01-01

    Motivated by important applications in materials science and geophysics, we consider the steady-state growth of anisotropic needle-like dendrites in undercooled binary mixtures with a forced convective flow. We analyse the stable mode of dendritic evolution in the case of small anisotropies of growth kinetics and surface energy for arbitrary Péclet numbers and n-fold symmetry of dendritic crystals. On the basis of solvability and stability theories, we formulate a selection criterion giving a stable combination between dendrite tip diameter and tip velocity. A set of nonlinear equations consisting of the solvability criterion and undercooling balance is solved analytically for the tip velocity V and tip diameter ρ of dendrites with n-fold symmetry in the absence of convective flow. The case of convective heat and mass transfer mechanisms in a binary mixture occurring as a result of intensive flows in the liquid phase is detailed. A selection criterion that describes such solidification conditions is derived. The theory under consideration comprises previously considered theoretical approaches and results as limiting cases. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

  13. Direct formation of new, phase-stable, and photoactive anatase-type Ti1-2XNbXScXO2 solid solution nanoparticles by hydrothermal method

    International Nuclear Information System (INIS)

    Hirano, Masanori; Ito, Takaharu

    2008-01-01

    A new anatase phase of photoactive Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) solid solutions was directly formed as nanoparticles from precursor solutions of TiOSO 4 , NbCl 5 , and Sc(NO 3 ) 3 under mild hydrothermal conditions at 180 deg. C for 5 h using the hydrolysis of urea. With the increase of the content of niobium and scandium from X = 0 to 0.2, the lattice parameters a 0 and c 0 , the crystallite size, and the optical band gap of anatase gradually increased. Their photocatalytic activity and adsorptivity were evaluated separately by the measurement of the concentration of methylene blue (MB) remained in the solution in the dark or under UV-light irradiation. The anatase-type Ti 1-2X Nb X Sc X O 2 (X = 0.05) showed approximately two times and three times as high photocatalytic activity as those of the hydrothermal anatase-type pure TiO 2 and commercially available reference pure TiO 2 (ST-01), respectively. The anatase phase of Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) existed stably up to 900 deg. C during heat treatment in air. New rutile-type Ti 1-2X Nb X Sc X O 2 solid solutions are formed through the phase transformation. The starting temperature of anatase-to-rutile phase transformation for Ti 1-2X Nb X Sc X O 2 (X = 0-0.2) solid solutions was delayed but its completing temperature was accelerated

  14. The Influence of Radiation on Pit Solution Chemistry as it Pertains to the Transition from Metastable to Stable Pitting in Steels

    International Nuclear Information System (INIS)

    Galuszka-Muga, Barbara; Muga, Luis M.

    2006-01-01

    Previous work relevant to current efforts is summarized. A description of an improved version of a new electrochemical probe, the ArtPit, is given. The distinct feature of the probe for investigating metastable pitting of carbon steels is specified and compared to other approaches. The electrochemical response of the ArtPit under the gamma irradiation and elevated temperature conditions that occur at high level waste (HLW) storage tanks is presented. In particular, the Tafel slope determinations and chemical analyses of the ArtPit confined volume electrolyte are described. Based on results a possible approach for reducing the corrosion rate of HLW tank walls is suggested. Additional statistical analysis of the occurrence of short duration (passivated pits) and long term (stable pitting) electrochemical pulses (current surges) during exposure confirm that radiation enhances the occurrence of both more and smaller sized pits due to increased likelihood of repassivation

  15. 1D and 2D NMR Spectroscopy of Bonding Interactions within Stable and Phase-Separating Organic Electrolyte-Cellulose Solutions.

    Science.gov (United States)

    Clough, Matthew T; Farès, Christophe; Rinaldi, Roberto

    2017-09-11

    Organic electrolyte solutions (i.e. mixtures containing an ionic liquid and a polar, molecular co-solvent) are highly versatile solvents for cellulose. However, the underlying solvent-solvent and solvent-solute interactions are not yet fully understood. Herein, mixtures of the ionic liquid 1-ethyl-3-methylimidazolium acetate, the co-solvent 1,3-dimethyl-2-imidazolidinone, and cellulose are investigated using 1D and 2D NMR spectroscopy. The use of a triply- 13 C-labelled ionic liquid enhances the signal-to-noise ratio for 13 C NMR spectroscopy, enabling changes in bonding interactions to be accurately pinpointed. Current observations reveal an additional degree of complexity regarding the distinct roles of cation, anion, and co-solvent toward maintaining cellulose solubility and phase stability. Unexpectedly, the interactions between the dialkylimidazolium ring C 2 -H substituent and cellulose become more pronounced at high temperatures, counteracted by a net weakening of acetate-cellulose interactions. Moreover, for mixtures that exhibit critical solution behavior, phase separation is accompanied by the apparent recombination of cation-anion pairs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1994-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets, with a few more additions - with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers - exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the foree of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc. (orig.)

  17. Stable particles

    International Nuclear Information System (INIS)

    Samios, N.P.

    1993-01-01

    I have been asked to review the subject of stable particles, essentially the particles that eventually comprised the meson and baryon octets. with a few more additions -- with an emphasis on the contributions made by experiments utilizing the bubble chamber technique. In this activity, much work had been done by the photographic emulsion technique and cloud chambers-exposed to cosmic rays as well as accelerator based beams. In fact, many if not most of the stable particles were found by these latter two techniques, however, the forte of the bubble chamber (coupled with the newer and more powerful accelerators) was to verify, and reinforce with large statistics, the existence of these states, to find some of the more difficult ones, mainly neutrals and further to elucidate their properties, i.e., spin, parity, lifetimes, decay parameters, etc

  18. Strategy of Solution-Processed All-Inorganic Heterostructure for Humidity/Temperature-Stable Perovskite Quantum Dot Light-Emitting Diodes.

    Science.gov (United States)

    Shi, Zhifeng; Li, Sen; Li, Ying; Ji, Huifang; Li, Xinjian; Wu, Di; Xu, Tingting; Chen, Yongsheng; Tian, Yongtao; Zhang, Yuantao; Shan, Chongxin; Du, Guotong

    2018-02-27

    Recently, a pressing requirement of solid-state lighting sources with high performance and low cost has motivated increasing research in metal halide perovskites. However, the relatively low emission efficiency and poor operation stability of perovskite light-emitting diodes (LEDs) are still critical drawbacks. In this study, a strategy of solution-processed all-inorganic heterostructure was proposed to overcome the emission efficiency and operation stability issues facing the challenges of perovskite LEDs. Solution-processed n-ZnO nanoparticles and p-NiO are used as the carrier injectors to fabricate all-inorganic heterostructured CsPbBr 3 quantum dot LEDs, and a high-efficiency green emission is achieved with maximum luminance of 6093.2 cd/m 2 , external quantum efficiency of 3.79%, and current efficiency of 7.96 cd/A. More importantly, the studied perovskite LEDs possess a good operation stability after a long test time in air ambient. Typically, the devices can endure a high humidity (75%, 12 h) and a high working temperature (393 K, three heating/cooling cycles) even without encapsulation, and the operation stability is better than any previous reports. It is anticipated that this work will provide an effective strategy for the fabrication of high-performance perovskite LEDs with good stability under ambient and harsh conditions, making practical applications of such LEDs a real possibility.

  19. One-pot synthesis of stable colloidal solutions of MFe{sub 2}O{sub 4} nanoparticles using oleylamine as solvent and stabilizer

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Mirabet, Leonardo [Departament de Química, Universitat Autònoma de Barcelona, Campus de la UAB, 08193 Bellaterra (Spain); Solano, Eduardo, E-mail: eduardo.solano@uab.cat [Departament de Química, Universitat Autònoma de Barcelona, Campus de la UAB, 08193 Bellaterra (Spain); Martínez-Julián, Fernando; Guzmán, Roger [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra (Spain); Arbiol, Jordi [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08019 Barcelona (Spain); Puig, Teresa; Obradors, Xavier; Pomar, Alberto [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra (Spain); Yáñez, Ramón; Ros, Josep [Departament de Química, Universitat Autònoma de Barcelona, Campus de la UAB, 08193 Bellaterra (Spain); Ricart, Susagna [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra (Spain)

    2013-03-15

    Highlights: ► One-pot synthesis of ferrite magnetic nanoparticles (<10 nm) in non-polar media. ► Nanoparticles present high monocrystal quality and monodispersion. ► Superparamagnetic behavior at room temperature. ► Nanoparticles transfer to polar media via ligand exchange. - Abstract: An easy, efficient, reproducible and scalable one-pot synthetic methodology to obtain magnetic spinel ferrite nanoparticles has been developed. This approach is based on one-pot thermal decomposition of Fe(acac){sub 3} and M(acac){sub 2} (M = Co, Mn, Cu and Zn) in oleylamine, which also acts as a capping ligand, by producing stable colloidal dispersions of nanoparticles in non-polar solvents. The properties of the nanoparticles have been studied via different techniques, such as transmission electron microscopy, which shows that nanoparticles are monocrystallines and a narrow dispersion in size; magnetic analyses have demonstrated that the resulting ferrite nanoparticles show high saturation values and superparamagnetic behavior at room temperature; X-ray diffraction has also been performed, and it confirms that the synthesized nanoparticles have a spinel structure. Complementarily, ligand exchange has been also carried out in order to produce dispersions of the synthesized nanoparticles in polar media.

  20. The multi-period solution of a linear system of equations with the operator of differentiation along the main diagonal of the space of independent variables and delayed arguments

    Science.gov (United States)

    Sartabanov, Zhaishylyk A.

    2017-09-01

    A new approach to the study of periodic by all independent variables system of equations with a differentiation operator solutions along the direction of the main diagonal and with delayed arguments is proposed. The essence of the approach is to reduce the study of the multi-periodic solution of a linear inhomogeneous system to the construction of a solution of a simpler linear differential-difference system on the basis of the method of variating arbitrary constants of the complete integral of a homogeneous system. An integral representation of the unique multiperiodic solution of an inhomogeneous system is presented, expressed by a functional series of terms given by multiple repeated integrals. An estimate is given for the norm of a multi-periodic solution.

  1. The Influence of Radiation on Pit Solution Chemistry as it Pertains to the Transition from Metastable to Stable Pitting in Steels.

    Energy Technology Data Exchange (ETDEWEB)

    Galuszka-Muga, Barbara

    2005-05-19

    An investigation was undertaken of the effect of gamma radiation on metastable pitting of mild carbon steels immersed in a solution similar to those existing at high level waste (HLW) deposits in the US. The object was to observe the extent to which a dosage rate of 1 Mrad/hour (10 Kgrey/hour) affected measurable electrochemical parameters such as pitting potential, open circuit potential, rate of metastable pitting and repassivation potential. Methods for reliably measuring electrochemical potentials in a high radiation field were developed. Exploratory analyses were made of the ion product release and electrolyte composition change in a confined volume simulating the conditions of a corrosion initiated pit during gamma irradiation. As expected the results indicated that the metastable pitting rate (as well as the general rate of corrosion) was significantly enhanced by a radiation field.

  2. Travelling waves in models of neural tissue: from localised structures to periodic waves

    NARCIS (Netherlands)

    Meijer, Hil Gaétan Ellart; Coombes, Stephen

    2014-01-01

    We consider travelling waves (fronts, pulses and periodics) in spatially extended one dimensional neural field models. We demonstrate for an excitatory field with linear adaptation that, in addition to an expected stable pulse solution, a stable anti-pulse can exist. Varying the adaptation strength

  3. Fabrication of Stable and Regenerable Amine Functionalized Magnetic Nanoparticles as a Potential Material for Pt(IV) Recovery from Acidic Solutions.

    Science.gov (United States)

    Reddy, D Harikishore Kumar; Wei, Wei; Shuo, Lin; Song, Myung-Hee; Yun, Yeoung-Sang

    2017-06-07

    MnFe 2 O 4 @SiO 2 -NH 2 magnetic nanocomposite (AFMNC) adsorbent with a particle size of ∼50 nm was successfully synthesized using a facile approach. The as-prepared composite particles showed a fast binding of Pt(IV) with easy magnetic solid-liquid separation. The kinetic data were fitted to both pseudo-first and second-order rate models, indicating that AFMNC exhibited a much higher rate of Pt(IV) binding (0.125 g mg -1 min -1 ) compared to that of commercial ion-exchange resin Amberjet 4200 (0.0002 g mg -1 min -1 ). The equilibrium adsorption data were fitted to the Langmuir isotherm model with a relatively high sorption capacity of 380 mg/g. Scanning transmission electron microscopy analysis demonstrated the presence of platinum chloride after sorption on AFMNC, suggesting an adsorbate-adsorbent anion-exchange interaction. In addition, due to its magnetic characteristics, AFMNC can be easily separated from the aqueous medium after the sorption process. The novel nanocomposite may facilitate recovery of Pt(IV) from waste solutions.

  4. Improved electron injection and transport by use of baking soda as a low-cost, air-stable, n-dopant for solution-processed phosphorescent organic light-emitting diodes

    Science.gov (United States)

    Earmme, Taeshik; Jenekhe, Samson A.

    2013-06-01

    Sodium bicarbonate (baking soda, NaHCO3) is found to be an efficient low-cost, air-stable, and environmentally friendly n-dopant for electron-transport layer (ETL) in solution-processed phosphorescent organic light-emitting diodes (PhOLEDs). A 2.0-fold enhancement in power efficiency of blue PhOLEDs is observed by use of NaHCO3-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) ETL. The bulk conductivity of NaHCO3-doped BPhen film is increased by 5 orders of magnitude. Enhanced performance of PhOLEDs is similarly observed by use of NaHCO3-doped 1,3,5-tris(m-pyrid-3-yl-phenyl)benzene ETL. These results demonstrate that sodium bicarbonate is an effective n-dopant in organic electronics.

  5. Monotonic Stable Solutions for Minimum Coloring Games

    NARCIS (Netherlands)

    Hamers, H.J.M.; Miquel, S.; Norde, H.W.

    2011-01-01

    For the class of minimum coloring games (introduced by Deng et al. (1999)) we investigate the existence of population monotonic allocation schemes (introduced by Sprumont (1990)). We show that a minimum coloring game on a graph G has a population monotonic allocation scheme if and only if G is (P4,

  6. Monotonic stable solutions for minimum coloring games

    NARCIS (Netherlands)

    Hamers, H.J.M.; Miquel, S.; Norde, H.W.

    2014-01-01

    For the class of minimum coloring games (introduced by Deng et al. Math Oper Res, 24:751–766, 1999) we investigate the existence of population monotonic allocation schemes (introduced by Sprumont Games Econ Behav 2:378–394, 1990). We show that a minimum coloring game on a graph G has a population

  7. On the stability, the periodic solutions and the resolution of certain types of non linear equations, and of non linearly coupled systems of these equations, appearing in betatronic oscillations

    International Nuclear Information System (INIS)

    Valat, J.

    1960-12-01

    Universal stability diagrams have been calculated and experimentally checked for Hill-Meissner type equations with square-wave coefficients. The study of these equations in the phase-plane has then made it possible to extend the periodic solution calculations to the case of non-linear differential equations with periodic square-wave coefficients. This theory has been checked experimentally. For non-linear coupled systems with constant coefficients, a search was first made for solutions giving an algebraic motion. The elliptical and Fuchs's functions solve such motions. The study of non-algebraic motions is more delicate, apart from the study of nonlinear Lissajous's motions. A functional analysis shows that it is possible however in certain cases to decouple the system and to find general solutions. For non-linear coupled systems with periodic square-wave coefficients it is then possible to calculate the conditions leading to periodic solutions, if the two non-linear associated systems with constant coefficients fall into one of the categories of the above paragraph. (author) [fr

  8. Solutions of the coupled Higgs field equations

    Science.gov (United States)

    Talukdar, Benoy; Ghosh, Swapan K.; Saha, Aparna; Pal, Debabrata

    2013-07-01

    By an appropriate choice for the phase of the complex nucleonic field and going over to the traveling coordinate, we reduce the coupled Higgs equations to the Hamiltonian form and treat the resulting equation using the dynamical system theory. We present a phase-space analysis of its stable points. The results of our study demonstrate that the equation can support both traveling- and standing-wave solutions. The traveling-wave solution appears in the form of a soliton and resides in the midst of doubly periodic standing-wave solutions.

  9. Stable Isotope Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

  10. Effects of oral carbohydrate with amino acid solution on the metabolic status of patients in the preoperative period: a randomized, prospective clinical trial.

    Science.gov (United States)

    Tsutsumi, Rie; Kakuta, Nami; Kadota, Takako; Oyama, Takuro; Kume, Katsuyoshi; Hamaguchi, Eisuke; Niki, Noriko; Tanaka, Katsuya; Tsutsumi, Yasuo M

    2016-10-01

    Enhanced recovery after surgery is increasingly desired nowadays, and preoperative nutrient intake may be beneficial for this purpose. In this study, we investigated whether the intake of preoperative carbohydrate with amino acid (ONS) solution can improve starvation status and lipid catabolism before the induction of anesthesia. This randomized, prospective clinical trial included 24 patients who were divided into two groups before surgery under general anesthesia: a control group, comprising patients who fasted after their last meal the day before surgery (permitted to drink only water), and an ONS group, comprising patients who consumed ONS solution 2 h before surgery. Biochemical markers, the respiratory quotient, and psychosomatic scores were assessed at the initiation of anesthesia. Compared with the control group, the ONS group showed significantly lower serum free fatty acid levels [control group: 828 (729, 1004) µEq/L, ONS group: 479 (408, 610) µEq/L, P = 0.0002, median (25th, 75th percentile)] and total ketone bodies [control group: 119 (68, 440) µmol/L, ONS group: 40 [27, 64] µmol/L, P = 0.037]. In addition, analysis using the Visual Analog Scale showed higher preoperative scores for anxiety, hunger, and thirst for the control group, with no differences in any other measure of subjective well-being between groups. The results of this study suggest that preoperative ONS intake improves lipid catabolism and starvation status before the induction of anesthesia. Furthermore, it can provide better preoperative mental health compared with complete fasting.

  11. A timeline of stable isotopes and mass spectrometry in the life sciences.

    Science.gov (United States)

    Lehmann, Wolf D

    2017-01-01

    This review retraces the role of stable isotopes and mass spectrometry in the life sciences. The timeline is divided into four segments covering the years 1920-1950, 1950-1980, 1980-2000, and 2000 until today. For each period methodic progress and typical applications are discussed. Application of stable isotopes is driven by improvements of mass spectrometry, chromatography, and related fields in sensitivity, mass accuracy, structural specificity, complex sample handling ability, data output, and data evaluation. We currently experience the vision of omics-type analyses, that is, the comprehensive identification and quantification of a complete compound class within one or a few analytical runs. This development is driven by stable isotopes without competition by radioisotopes. In metabolic studies as classic field of isotopic tracer experiments, stable isotopes and radioisotopes were competing solutions, with stable isotopes as the long-term junior partner. Since the 1990s the number of metabolic studies with radioisotopes decreases, whereas stable isotope studies retain their slow but stable upward tendency. Unique fields of stable isotopes are metabolic tests in newborns, metabolic experiments in healthy controls, newborn screening for inborn errors, quantification of drugs and drug metabolites in doping control, natural isotope fractionation in geology, ecology, food authentication, or doping control, and more recently the field of quantitative omics-type analyses. There, cells or whole organisms are systematically labeled with stable isotopes to study proteomic differences or specific responses to stimuli or genetic manipulation. The duo of stable isotopes and mass spectrometry will probably continue to grow in the life sciences, since it delivers reference-quality quantitative data with molecular specificity, often combined with informative isotope effects. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:58-85, 2017. © 2016 Wiley Periodicals, Inc.

  12. Stable convergence and stable limit theorems

    CERN Document Server

    Häusler, Erich

    2015-01-01

    The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

  13. Bifurcations of a periodically forced microbial continuous culture model with restrained growth rate

    Science.gov (United States)

    Ren, Jingli; Yuan, Qigang

    2017-08-01

    A three dimensional microbial continuous culture model with a restrained microbial growth rate is studied in this paper. Two types of dilution rates are considered to investigate the dynamic behaviors of the model. For the unforced system, fold bifurcation and Hopf bifurcation are detected, and numerical simulations reveal that the system undergoes degenerate Hopf bifurcation. When the system is periodically forced, bifurcation diagrams for periodic solutions of period-one and period-two are given by researching the Poincaré map, corresponding to different bifurcation cases in the unforced system. Stable and unstable quasiperiodic solutions are obtained by Neimark-Sacker bifurcation with different parameter values. Periodic solutions of various periods can occur or disappear and even change their stability, when the Poincaré map of the forced system undergoes Neimark-Sacker bifurcation, flip bifurcation, and fold bifurcation. Chaotic attractors generated by a cascade of period doublings and some phase portraits are given at last.

  14. Stable agents for imaging investigations

    International Nuclear Information System (INIS)

    Tofe, A.J.

    1976-01-01

    This invention concerns highly stable compounds useful in preparing technetium 99m based scintiscanning exploration agents. The compounds of this invention include a pertechnetate reducing agent or a solution of oxidized pertechnetate and an efficient proportion, sufficient to stabilize the compounds in the presence of oxygen and of radiolysis products, of ascorbic acid or a pharmaceutically acceptable salt or ester of this acid. The invention also concerns a perfected process for preparing a technetium based exploration agent, consisting in codissolving the ascorbic acid or a pharmaceutically acceptable salt or ester of such an acid and a pertechnetate reducing agent in a solution of oxidized pertechnetate [fr

  15. Periodic oscillation and exponential stability of delayed CNNs

    Science.gov (United States)

    Cao, Jinde

    2000-05-01

    Both the global exponential stability and the periodic oscillation of a class of delayed cellular neural networks (DCNNs) is further studied in this Letter. By applying some new analysis techniques and constructing suitable Lyapunov functionals, some simple and new sufficient conditions are given ensuring global exponential stability and the existence of periodic oscillatory solution of DCNNs. These conditions can be applied to design globally exponentially stable DCNNs and periodic oscillatory DCNNs and easily checked in practice by simple algebraic methods. These play an important role in the design and applications of DCNNs.

  16. Green-roof as a solution to solve stormwater management issues? Assessment on a long time period at the parcel scale

    Directory of Open Access Journals (Sweden)

    P.-A. Versini

    2014-09-01

    Full Text Available Experimental green-roof rainfall–runoff observations have shown a positive impact on stormwater management at the building scale; with a decrease in the peak discharge and a decrease in runoff volume. This efficiency of green-roofs varies from one rainfall event to another depending on precipitation characteristics and substrate antecedent conditions. Due to this variability, currently, green-roofs are rarely officially used as a regulation tool to manage stormwater. Indeed, regulation rules governing the connection to the stormwater network are usually based on absolute threshold values that always have to be respected: maximum areal flow-rate or minimum retention volume for example. In this context, the aim of this study is to illustrate how a green-roof could represent an alternative to solve stormwater management issues, if the regulation rules were further based on statistics. For this purpose, a modelling scheme has been established at the parcel scale to simulate the hydrological response of several roof configurations: impervious, strictly regulated (in terms of areal flow-rate or retention volume, and covered by different types of green-roof matter. Simulations were carried out on a long precipitation time period (23 years that included a large and heterogeneous set of hydrometeorological conditions. Results obtained for the different roof configurations were compared. Based on the return period of the rainfall event, the probability to respect some regulation rules (defined from real situations was assessed. They illustrate that green-roofs reduce stormwater runoff compared to an impervious roof surface and can guarantee the respect of the regulation rules in most of the cases. Moreover, their implementation can appear more realistic than that of other infrastructures strictly complying with regulations and demanding significant storage capacity.

  17. Two stable steady states in the Hodgkin-Huxley axons

    OpenAIRE

    Aihara, K.; Matsumoto, G.

    1983-01-01

    Two stable steady states were found in the numerical solution of the Hodgkin-Huxley equations for the intact squid axon bathed in potassium-rich sea water with an externally applied inward current. Under the conditions the two stable steady-states exist, the Hodgkin-Huxley equations have a complex bifurcation structure including, in addition to the two stable steady-states, a stable limit cycle, two unstable equilibrium points, and one asymptotically stable equilibrium point. It was also conc...

  18. Oscillating solutions of the Vlasov-Poisson system-A numerical investigation

    Science.gov (United States)

    Ramming, Tobias; Rein, Gerhard

    2018-02-01

    Numerical evidence is given that spherically symmetric perturbations of stable spherically symmetric steady states of the gravitational Vlasov-Poisson system lead to solutions which oscillate in time. The oscillations can be periodic in time or damped. Along one-parameter families of polytropic steady states we establish an Eddington-Ritter type relation which relates the period of the oscillation to the central density of the steady state. The numerically obtained periods are used to estimate possible periods for typical elliptical galaxies.

  19. On the stability, the periodic solutions and the resolution of certain types of non linear equations, and of non linearly coupled systems of these equations, appearing in betatronic oscillations; Sur la stabilite, les solutions periodiques et la resolution de certaines categories d'equations et systemes d'equations differentielles couplees non lineaires apparaissant dans les oscillations betatroniques

    Energy Technology Data Exchange (ETDEWEB)

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

    1960-12-15

    Universal stability diagrams have been calculated and experimentally checked for Hill-Meissner type equations with square-wave coefficients. The study of these equations in the phase-plane has then made it possible to extend the periodic solution calculations to the case of non-linear differential equations with periodic square-wave coefficients. This theory has been checked experimentally. For non-linear coupled systems with constant coefficients, a search was first made for solutions giving an algebraic motion. The elliptical and Fuchs's functions solve such motions. The study of non-algebraic motions is more delicate, apart from the study of nonlinear Lissajous's motions. A functional analysis shows that it is possible however in certain cases to decouple the system and to find general solutions. For non-linear coupled systems with periodic square-wave coefficients it is then possible to calculate the conditions leading to periodic solutions, if the two non-linear associated systems with constant coefficients fall into one of the categories of the above paragraph. (author) [French] Pour les equations du genre de Hill-Meissner a coefficients creneles, on a calcule des diagrammes universels de stabilite et ceux-ci ont ete verifies experimentalement. L'etude de ces equations dans le plan de phase a permis ensuite d'etendre le calcul des solutions periodiques au cas des equations differentielles non lineaires a coefficients periodiques creneles. Cette theorie a ete verifiee experimentalement. Pour Jes systemes couples non lineaires a coefficients constants, on a d'abord cherche les solutions menant a des mouvements algebriques. Les fonctions elliptiques et fuchsiennes uniformisent de tels mouvements. L'etude de mouvements non algebriques est plus delicate, a part l'etude des mouvements de Lissajous non lineaires. Une analyse fonctionnelle montre qu'il est toutefois possible dans certains cas de decoupler le systeme et de

  20. stableGP

    Data.gov (United States)

    National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...

  1. Marginally Stable Nuclear Burning

    Science.gov (United States)

    Strohmayer, Tod E.; Altamirano, D.

    2012-01-01

    Thermonuclear X-ray bursts result from unstable nuclear burning of the material accreted on neutron stars in some low mass X-ray binaries (LMXBs). Theory predicts that close to the boundary of stability oscillatory burning can occur. This marginally stable regime has so far been identified in only a small number of sources. We present Rossi X-ray Timing Explorer (RXTE) observations of the bursting, high- inclination LMXB 4U 1323-619 that reveal for the first time in this source the signature of marginally stable burning. The source was observed during two successive RXTE orbits for approximately 5 ksec beginning at 10:14:01 UTC on March 28, 2011. Significant mHz quasi- periodic oscillations (QPO) at a frequency of 8.1 mHz are detected for approximately 1600 s from the beginning of the observation until the occurrence of a thermonuclear X-ray burst at 10:42:22 UTC. The mHz oscillations are not detected following the X-ray burst. The average fractional rms amplitude of the mHz QPOs is 6.4% (3 - 20 keV), and the amplitude increases to about 8% below 10 keV.This phenomenology is strikingly similar to that seen in the LMXB 4U 1636-53. Indeed, the frequency of the mHz QPOs in 4U 1323-619 prior to the X-ray burst is very similar to the transition frequency between mHz QPO and bursts found in 4U 1636-53 by Altamirano et al. (2008). These results strongly suggest that the observed QPOs in 4U 1323-619 are, like those in 4U 1636-53, due to marginally stable nuclear burning. We also explore the dependence of the energy spectrum on the oscillation phase, and we place the present observations within the context of the spectral evolution of the accretion-powered flux from the source.

  2. Initial Stages in the Rhodium(III)-Catalyzed C-H Bond Activation of Primary Alcohols in Aqueous Solution

    DEFF Research Database (Denmark)

    Eriksen, J.; Monsted, L.; Monsted, O.

    2010-01-01

    ,4,8,11-tetraazacyclotetradecane) cation. The hydride complex is stable for extended periods of time in acidic solution in the absence of oxidants. In basic solutions a series of base-catalyzed reactions take place to yield ultimately the same mixture of [Rh(cycb)(OH)(2)](+) isomers as produced by base hydrolysis of the trans...

  3. Period Cramps

    Science.gov (United States)

    ... Safe Videos for Educators Search English Español Period Cramps KidsHealth / For Kids / Period Cramps Print en español ... a girl who gets them. What Are Period Cramps? Lots of girls experience cramps before or during ...

  4. Structure of acid-stable carmine.

    Science.gov (United States)

    Sugimoto, Naoki; Kawasaki, Yoko; Sato, Kyoko; Aoki, Hiromitsu; Ichi, Takahito; Koda, Takatoshi; Yamazaki, Takeshi; Maitani, Tamio

    2002-02-01

    Acid-stable carmine has recently been distributed in the U.S. market because of its good acid stability, but it is not permitted in Japan. We analyzed and determined the structure of the major pigment in acid-stable carmine, in order to establish an analytical method for it. Carminic acid was transformed into a different type of pigment, named acid-stable carmine, through amination when heated in ammonia solution. The features of the structure were clarified using a model compound, purpurin, in which the orientation of hydroxyl groups on the A ring of the anthraquinone skeleton is the same as that of carminic acid. By spectroscopic means and the synthesis of acid-stable carmine and purpurin derivatives, the structure of the major pigment in acid-stable carmine was established as 4-aminocarminic acid, a novel compound.

  5. Diffractons: Solitary Waves Created by Diffraction in Periodic Media

    KAUST Repository

    Ketcheson, David I.

    2015-03-31

    A new class of solitary waves arises in the solution of nonlinear wave equations with constant impedance and no dispersive terms. These solitary waves depend on a balance between nonlinearity and a dispersion-like effect due to spatial variation in the sound speed of the medium. A high-order homogenized model confirms this effective dispersive behavior, and its solutions agree well with those obtained by direct simulation of the variable-coefficient system. These waves are observed to be long-time stable, globally attracting solutions that arise in general as solutions to nonlinear wave problems with periodically varying sound speed. They share some properties with known classes of solitary waves but possess important differences as well.

  6. A stable high-order perturbation of surfaces method for numerical simulation of diffraction problems in triply layered media

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Youngjoon, E-mail: hongy@uic.edu; Nicholls, David P., E-mail: davidn@uic.edu

    2017-02-01

    The accurate numerical simulation of linear waves interacting with periodic layered media is a crucial capability in engineering applications. In this contribution we study the stable and high-order accurate numerical simulation of the interaction of linear, time-harmonic waves with a periodic, triply layered medium with irregular interfaces. In contrast with volumetric approaches, High-Order Perturbation of Surfaces (HOPS) algorithms are inexpensive interfacial methods which rapidly and recursively estimate scattering returns by perturbation of the interface shape. In comparison with Boundary Integral/Element Methods, the stable HOPS algorithm we describe here does not require specialized quadrature rules, periodization strategies, or the solution of dense non-symmetric positive definite linear systems. In addition, the algorithm is provably stable as opposed to other classical HOPS approaches. With numerical experiments we show the remarkable efficiency, fidelity, and accuracy one can achieve with an implementation of this algorithm.

  7. Thermally stable nanoparticles on supports

    Science.gov (United States)

    Roldan Cuenya, Beatriz; Naitabdi, Ahmed R.; Behafarid, Farzad

    2012-11-13

    An inverse micelle-based method for forming nanoparticles on supports includes dissolving a polymeric material in a solvent to provide a micelle solution. A nanoparticle source is dissolved in the micelle solution. A plurality of micelles having a nanoparticle in their core and an outer polymeric coating layer are formed in the micelle solution. The micelles are applied to a support. The polymeric coating layer is then removed from the micelles to expose the nanoparticles. A supported catalyst includes a nanocrystalline powder, thin film, or single crystal support. Metal nanoparticles having a median size from 0.5 nm to 25 nm, a size distribution having a standard deviation .ltoreq.0.1 of their median size are on or embedded in the support. The plurality of metal nanoparticles are dispersed and in a periodic arrangement. The metal nanoparticles maintain their periodic arrangement and size distribution following heat treatments of at least 1,000.degree. C.

  8. Stable isotopes labelled compounds

    International Nuclear Information System (INIS)

    1982-09-01

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  9. Stable Boundary Layer Issues

    NARCIS (Netherlands)

    Steeneveld, G.J.

    2012-01-01

    Understanding and prediction of the stable atmospheric boundary layer is a challenging task. Many physical processes are relevant in the stable boundary layer, i.e. turbulence, radiation, land surface coupling, orographic turbulent and gravity wave drag, and land surface heterogeneity. The

  10. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    IAS Admin

    After Maynard-Smith and Price [1] mathematically derived why a given behaviour or strategy was adopted by a certain proportion of the population at a given time, it was shown that a strategy which is currently stable in a population need not be stable in evolutionary time (across generations). Additionally it was sug-.

  11. Occurrence of stable periodic modes in a pendulum with cubic ...

    Indian Academy of Sciences (India)

    In this work the driven Froude pendulum is studied by the harmonic balancing method; the resulting nonlinear response curves are studied further for resonance and stability of symmetric oscillations with relatively low damping. The stability analysis is carried out by transforming the system of equations to the linear Mathieu ...

  12. Problem Periods

    Science.gov (United States)

    ... during your menstrual cycle Premenstrual syndrome (PMS) Problem periods Getting enough sleep Looking and feeling your best Fighting germs Your sexuality What are STDs and STIs? Seeing the doctor Quizzes Links to more information on girls' bodies girlshealth glossary girlshealth.gov home http://www.girlshealth.gov/ Home ... Problem periods It’s common to have ...

  13. Turing patterns in parabolic systems of conservation laws and numerically observed stability of periodic waves

    Science.gov (United States)

    Barker, Blake; Jung, Soyeun; Zumbrun, Kevin

    2018-03-01

    Turing patterns on unbounded domains have been widely studied in systems of reaction-diffusion equations. However, up to now, they have not been studied for systems of conservation laws. Here, we (i) derive conditions for Turing instability in conservation laws and (ii) use these conditions to find families of periodic solutions bifurcating from uniform states, numerically continuing these families into the large-amplitude regime. For the examples studied, numerical stability analysis suggests that stable periodic waves can emerge either from supercritical Turing bifurcations or, via secondary bifurcation as amplitude is increased, from subcritical Turing bifurcations. This answers in the affirmative a question of Oh-Zumbrun whether stable periodic solutions of conservation laws can occur. Determination of a full small-amplitude stability diagram - specifically, determination of rigorous Eckhaus-type stability conditions - remains an interesting open problem.

  14. Normal modified stable processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Shephard, N.

    2002-01-01

    This paper discusses two classes of distributions, and stochastic processes derived from them: modified stable (MS) laws and normal modified stable (NMS) laws. This extends corresponding results for the generalised inverse Gaussian (GIG) and generalised hyperbolic (GH) or normal generalised inverse...... Gaussian (NGIG) laws. The wider framework thus established provides, in particular, for added flexibility in the modelling of the dynamics of financial time series, of importance especially as regards OU based stochastic volatility models for equities. In the special case of the tempered stable OU process...

  15. Applications of stable isotopes

    International Nuclear Information System (INIS)

    Letolle, R.; Mariotti, A.; Bariac, T.

    1991-06-01

    This report reviews the historical background and the properties of stable isotopes, the methods used for their measurement (mass spectrometry and others), the present technics for isotope enrichment and separation, and at last the various present and foreseeable application (in nuclear energy, physical and chemical research, materials industry and research; tracing in industrial, medical and agronomical tests; the use of natural isotope variations for environmental studies, agronomy, natural resources appraising: water, minerals, energy). Some new possibilities in the use of stable isotope are offered. A last chapter gives the present state and forecast development of stable isotope uses in France and Europe

  16. Historiske perioder

    DEFF Research Database (Denmark)

    2017-01-01

    For at forstå fortiden og fortællingerne om den, må vi skabe en form for orden og systematik. Her spiller inddelingen af fortiden i historiske perioder en afgørende rolle – og historiske perioder er da også et kompetencemål efter 6. klasse. Videoen diskuterer forskellige principper...... for periodisering. Kronologi og sammenhænge hænger naturligt sammen med historiske perioder. Videoen handler også om forståelser og brug af synkrone og diakrone sammenhænge i faget....

  17. Analysing Stable Time Series

    National Research Council Canada - National Science Library

    Adler, Robert

    1997-01-01

    We describe how to take a stable, ARMA, time series through the various stages of model identification, parameter estimation, and diagnostic checking, and accompany the discussion with a goodly number...

  18. Sodium tetraphenylborate solution stability: A long term study

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, M.J.

    1992-06-11

    Sodium tetraphenylborata (NaTPB) is a specialty chemical required for the In Tank Precipitation Process (ITP). It precipitates cesium, aiding in the decontamination of high level radioactive waste solutions. Long term stability of aqueous alkaline solutions of NATPB has been investigated. The focus of the investigation is on the relative stabilities of NATPB solutions exposed to varying temperatures and copper concentrations over an extended period of time. Additionally, vendor-supplied samples, incubated at 40{degree}C, were stored for more than a year without decomposing. Collected data demonstrates that in the absence of elevated copper concentrations, NATPB solutions will remain stable for periods of 1 to 2 years (at a minimum) at maximum expected operating conditions (<40{degree}C). Additionally, biuret, (H{sub 2}NCO){sub 2}NH, was tested as an additive to prevent copper-induced decomposition without success.

  19. Sodium tetraphenylborate solution stability: A long term study

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, M.J.

    1992-06-11

    Sodium tetraphenylborata (NaTPB) is a specialty chemical required for the In Tank Precipitation Process (ITP). It precipitates cesium, aiding in the decontamination of high level radioactive waste solutions. Long term stability of aqueous alkaline solutions of NATPB has been investigated. The focus of the investigation is on the relative stabilities of NATPB solutions exposed to varying temperatures and copper concentrations over an extended period of time. Additionally, vendor-supplied samples, incubated at 40[degree]C, were stored for more than a year without decomposing. Collected data demonstrates that in the absence of elevated copper concentrations, NATPB solutions will remain stable for periods of 1 to 2 years (at a minimum) at maximum expected operating conditions (<40[degree]C). Additionally, biuret, (H[sub 2]NCO)[sub 2]NH, was tested as an additive to prevent copper-induced decomposition without success.

  20. On Stable Marriages and Greedy Matchings

    Energy Technology Data Exchange (ETDEWEB)

    Manne, Fredrik; Naim, Md; Lerring, Hakon; Halappanavar, Mahantesh

    2016-12-11

    Research on stable marriage problems has a long and mathematically rigorous history, while that of exploiting greedy matchings in combinatorial scientific computing is a younger and less developed research field. In this paper we consider the relationships between these two areas. In particular we show that several problems related to computing greedy matchings can be formulated as stable marriage problems and as a consequence several recently proposed algorithms for computing greedy matchings are in fact special cases of well known algorithms for the stable marriage problem. However, in terms of implementations and practical scalable solutions on modern hardware, the greedy matching community has made considerable progress. We show that due to the strong relationship between these two fields many of these results are also applicable for solving stable marriage problems.

  1. Stable black phosphorus quantum dots for alkali PH sensor

    Science.gov (United States)

    Guo, Weilan; Song, Haizeng; Yan, Shancheng

    2018-01-01

    Black phosphorus, as a new two-dimensional material has been widely used in sensors, photovoltaic devices, etc. However, thin layered black phosphorus chemically degrades rapidly under ambient and aqueous conditions, which hinders the application of it in the chemical sensors. In this work, stable black phosphorus quantum dots (BPQDs) in solution are successfully synthesized by functionalization with 4-nitrobenzene-diazonium (4-NBD). The stable BPQDs are investigated by TEM, AFM, Raman, and UV-absorption. As a potential application, the stable BPQDs are used as sensors in alkali solution, which exhibit outstanding performance. Our work paves the way towards a new application with BPQDs in solution.

  2. Induction period

    International Nuclear Information System (INIS)

    Land, C.E.; Tokunaga, M.

    1984-01-01

    Induction period is the temporal aspect of the excess cancer risk that follows an exposure to ionizing radiation. Operationally, it can be thought of as the time from an exposure of brief duration to the diagnosis of any resultant cancer. Whereas the magnitude of excess risk can be described by a single number, such as the average yearly excess risk over some fixed time interval after exposure, the temporal distribution requires a histogram or a curve, that is, an array or continuum of numbers. The study of induction period involves a search for a simple way of describing the temporal distribution of risk, that is, a way of describing a continuum by using only one or two numbers. In other words, the goal is to describe induction period probabilistically, using a parametric model with a few parameters

  3. Self-similar decay to the marginally stable ground state in a model for film flow over inclined wavy bottoms

    Directory of Open Access Journals (Sweden)

    Tobias Hacker

    2012-04-01

    Full Text Available The integral boundary layer system (IBL with spatially periodic coefficients arises as a long wave approximation for the flow of a viscous incompressible fluid down a wavy inclined plane. The Nusselt-like stationary solution of the IBL is linearly at best marginally stable; i.e., it has essential spectrum at least up to the imaginary axis. Nevertheless, in this stable case we show that localized perturbations of the ground state decay in a self-similar way. The proof uses the renormalization group method in Bloch variables and the fact that in the stable case the Burgers equation is the amplitude equation for long waves of small amplitude in the IBL. It is the first time that such a proof is given for a quasilinear PDE with spatially periodic coefficients.

  4. PERIODIC BEHAVIORS

    NARCIS (Netherlands)

    Napp, Diego; Put, Marius van der; Shankar, Shiva

    2010-01-01

    This paper studies behaviors that are defined on a torus, or equivalently, behaviors defined in spaces of periodic functions, and establishes their basic properties analogous to classical results of Malgrange, Palamodov, Oberst et al. for behaviors on R(n). These properties-in particular the

  5. Periodical Economics

    OpenAIRE

    King, Andrew

    2016-01-01

    This is the first overview of the economics of nineteenth-century periodicals and newspapers. While media economics is an established field in business studies, the chapter redefines economics by looking at value systems including capitalist ones but no confined to them. Original case studies are offered as models for research into the economics of nineteenth-century print culture.

  6. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  7. Stable States of Biological Organisms

    Science.gov (United States)

    Yukalov, V. I.; Sornette, D.; Yukalova, E. P.; Henry, J.-Y.; Cobb, J. P.

    2009-04-01

    A novel model of biological organisms is advanced, treating an organism as a self-consistent system subject to a pathogen flux. The principal novelty of the model is that it describes not some parts, but a biological organism as a whole. The organism is modeled by a five-dimensional dynamical system. The organism homeostasis is described by the evolution equations for five interacting components: healthy cells, ill cells, innate immune cells, specific immune cells, and pathogens. The stability analysis demonstrates that, in a wide domain of the parameter space, the system exhibits robust structural stability. There always exist four stable stationary solutions characterizing four qualitatively differing states of the organism: alive state, boundary state, critical state, and dead state.

  8. Solutions for the food processing industry; Shokuhin seizogyo solution

    Energy Technology Data Exchange (ETDEWEB)

    Toda, T.; Iwami, N. [Fuji Electric Co. Ltd., Tokyo (Japan)

    1999-09-10

    To improve quality control and maintain stable operation, the food processing industry requires problem solutions in total, including not only processing and operation control divisions but also quality control, design and production technology, and maintenance divisions. This paper describes solutions for HACCP (hazard analysis critical control point) support, quality control, and maintenance, in order to improve the quality level, ensure traceability and realize stable processing operations. (author)

  9. Evolutionary Stable Strategy

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 9. Evolutionary Stable Strategy: Application of Nash Equilibrium in Biology. General ... Using some examples of classical games, we show how evolutionary game theory can help understand behavioural decisions of animals.

  10. The Stable Concordance Genus

    OpenAIRE

    Kearney, M. Kate

    2013-01-01

    The concordance genus of a knot is the least genus of any knot in its concordance class. Although difficult to compute, it is a useful invariant that highlights the distinction between the three-genus and four-genus. In this paper we define and discuss the stable concordance genus of a knot, which describes the behavior of the concordance genus under connected sum.

  11. Manifolds admitting stable forms

    Czech Academy of Sciences Publication Activity Database

    Le, Hong-Van; Panák, Martin; Vanžura, Jiří

    2008-01-01

    Roč. 49, č. 1 (2008), s. 101-11 ISSN 0010-2628 R&D Projects: GA ČR(CZ) GP201/05/P088 Institutional research plan: CEZ:AV0Z10190503 Keywords : stable forms * automorphism groups Subject RIV: BA - General Mathematics

  12. Stable isotope studies

    International Nuclear Information System (INIS)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

  13. Interactive Stable Ray Tracing

    DEFF Research Database (Denmark)

    Dal Corso, Alessandro; Salvi, Marco; Kolb, Craig

    2017-01-01

    Interactive ray tracing applications running on commodity hardware can suffer from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-pr...

  14. The stable subgroup graph

    Directory of Open Access Journals (Sweden)

    Behnaz Tolue

    2018-07-01

    Full Text Available In this paper we introduce stable subgroup graph associated to the group $G$. It is a graph with vertex set all subgroups of $G$ and two distinct subgroups $H_1$ and $H_2$ are adjacent if $St_{G}(H_1\\cap H_2\

  15. Stable SU(5) monopoles with higher magnetic charge

    International Nuclear Information System (INIS)

    Miyamoto, S.; Sato, H.; Tomohiro, S.

    1985-01-01

    Taking into account the electroweak breaking effects, some multiply charged monopoles were shown to be stable by Gardner and Harvey. We give the explicit Ansa$uml: tze for finite-energy, nonsingular solutions of these stable higher-strength monopoles with eg = 1,(3/2),3. We also give the general stability conditions and the detailed behavior of the interaction potentials between two monopoles which produce the stable higher-strength monopoles

  16. Perturbation of an exact strong gravity solution

    International Nuclear Information System (INIS)

    Baran, S.A.

    1982-10-01

    Perturbations of an exact strong gravity solution are investigated. It is shown, by using the new multipole expansions previously presented, that this exact and static spherically symmetric solution is stable under odd parity perturbations. (author)

  17. Fractional CO2lasers contribute to the treatment of stable non-segmental vitiligo.

    Science.gov (United States)

    Yuan, Jinping; Chen, Hongqiang; Yan, Ru; Cui, Shaoshan; Li, Yuan-Hong; Wu, Yan; Gao, Xing-Hua; Chen, Hong-Duo

    2016-12-01

    Stable non-segmental vitiligo is often resistant to conventional therapies. The purpose of this study was to investigate the effect of three types of fractional lasers in the treatment of stable non-segmental vitiligo. Twenty patients were enrolled in the study. The vitiligo lesions of each patient were divided into four treatment parts, and all parts were treated with narrowband ultraviolet-B (NB-UVB). Three of the four parts were respectively treated with three types of fractional lasers (two ablative 10,600-nm CO 2 lasers and one non-ablative 1,565-nm laser), followed by topical betamethasone solution application. The treatment period lasted six months. Efficacy and satisfaction were respectively assessed by dermatologists and patients. The ablative CO 2 lasers, in combination with topical betamethasone solution and NB-UVB, achieved marked to excellent improvement on white patches assessed by dermatologists. Patients showed high satisfaction scores for the treatments. The non-ablative 1,565-nm fractional laser did not provide any further benefit in the treatment of vitiligo. No severe adverse events developed for any of the treatments. The treatment protocol with ablative CO 2 lasers, in combination with topical betamethasone solution and NB-UVB, was suitable for stable non-segmental vitiligo. For vitiligo, the ablative fractional CO 2 laser is more effective than the non-ablative fractional laser.

  18. Periodic paralysis.

    Science.gov (United States)

    Fialho, Doreen; Griggs, Robert C; Matthews, Emma

    2018-01-01

    The periodic paralyses are a group of skeletal muscle channelopathies characterizeed by intermittent attacks of muscle weakness often associated with altered serum potassium levels. The underlying genetic defects include mutations in genes encoding the skeletal muscle calcium channel Ca v 1.1, sodium channel Na v 1.4, and potassium channels K ir 2.1, K ir 3.4, and possibly K ir 2.6. Our increasing knowledge of how mutant channels affect muscle excitability has resulted in better understanding of many clinical phenomena which have been known for decades and sheds light on some of the factors that trigger attacks. Insights into the pathophysiology are also leading to new therapeutic approaches. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Stable isotope analysis

    International Nuclear Information System (INIS)

    Tibari, Elghali; Taous, Fouad; Marah, Hamid

    2014-01-01

    This report presents results related to stable isotopes analysis carried out at the CNESTEN DASTE in Rabat (Morocco), on behalf of Senegal. These analyzes cover 127 samples. These results demonstrate that Oxygen-18 and Deuterium in water analysis were performed by infrared Laser spectroscopy using a LGR / DLT-100 with Autosampler. Also, the results are expressed in δ values (‰) relative to V-SMOW to ± 0.3 ‰ for oxygen-18 and ± 1 ‰ for deuterium.

  20. Forensic Stable Isotope Biogeochemistry

    Science.gov (United States)

    Cerling, Thure E.; Barnette, Janet E.; Bowen, Gabriel J.; Chesson, Lesley A.; Ehleringer, James R.; Remien, Christopher H.; Shea, Patrick; Tipple, Brett J.; West, Jason B.

    2016-06-01

    Stable isotopes are being used for forensic science studies, with applications to both natural and manufactured products. In this review we discuss how scientific evidence can be used in the legal context and where the scientific progress of hypothesis revisions can be in tension with the legal expectations of widely used methods for measurements. Although this review is written in the context of US law, many of the considerations of scientific reproducibility and acceptance of relevant scientific data span other legal systems that might apply different legal principles and therefore reach different conclusions. Stable isotopes are used in legal situations for comparing samples for authenticity or evidentiary considerations, in understanding trade patterns of illegal materials, and in understanding the origins of unknown decedents. Isotope evidence is particularly useful when considered in the broad framework of physiochemical processes and in recognizing regional to global patterns found in many materials, including foods and food products, drugs, and humans. Stable isotopes considered in the larger spatial context add an important dimension to forensic science.

  1. Forward Period Analysis Method of the Periodic Hamiltonian System.

    Directory of Open Access Journals (Sweden)

    Pengfei Wang

    Full Text Available Using the forward period analysis (FPA, we obtain the period of a Morse oscillator and mathematical pendulum system, with the accuracy of 100 significant digits. From these results, the long-term [0, 1060] (time unit solutions, ranging from the Planck time to the age of the universe, are computed reliably and quickly with a parallel multiple-precision Taylor series (PMT scheme. The application of FPA to periodic systems can greatly reduce the computation time of long-term reliable simulations. This scheme provides an efficient way to generate reference solutions, against which long-term simulations using other schemes can be tested.

  2. Forward Period Analysis Method of the Periodic Hamiltonian System.

    Science.gov (United States)

    Wang, Pengfei

    2016-01-01

    Using the forward period analysis (FPA), we obtain the period of a Morse oscillator and mathematical pendulum system, with the accuracy of 100 significant digits. From these results, the long-term [0, 1060] (time unit) solutions, ranging from the Planck time to the age of the universe, are computed reliably and quickly with a parallel multiple-precision Taylor series (PMT) scheme. The application of FPA to periodic systems can greatly reduce the computation time of long-term reliable simulations. This scheme provides an efficient way to generate reference solutions, against which long-term simulations using other schemes can be tested.

  3. Bordism, stable homotopy and adams spectral sequences

    CERN Document Server

    Kochman, Stanley O

    1996-01-01

    This book is a compilation of lecture notes that were prepared for the graduate course "Adams Spectral Sequences and Stable Homotopy Theory" given at The Fields Institute during the fall of 1995. The aim of this volume is to prepare students with a knowledge of elementary algebraic topology to study recent developments in stable homotopy theory, such as the nilpotence and periodicity theorems. Suitable as a text for an intermediate course in algebraic topology, this book provides a direct exposition of the basic concepts of bordism, characteristic classes, Adams spectral sequences, Brown-Peter

  4. Structure and Dynamics of Thin Ionomer Films: a Key to A Stable Fuel Cell Membrane.

    Science.gov (United States)

    Perahia, Dvora

    2000-03-01

    The technology for solid polymeric electrolytic membranes for a fuel cells, calls for the thinnest film which is electrochemically stable. At present, none supported polymeric solid state fuel cell membranes, thinner than 50 microns, fail mechanically during fuel cell operation. When approaching the thin film limits, interfacial effects become significant to structure dynamics and consequently, the stability of the membranes. Our work focuses on understanding the interfacial effects on thin per-fluorinated ionomer films, including interfacial effects on the thin films themselves and nanotubes-thin film complexes, mimicking the catalyst-ionomer complexes. In particular we investigated the dynamics and structure in 500 angstrom and less, films made by several perfluorinated ionomers, cast on a solid support. Both the films and their parent solutions were investigated with the goal of resolving the factors that affect the stability in the ultra thin regime. AFM/STM and X-ray and neutron reflectivity were used to investigate the thin films and small angle neutron scattering was utilized to the study of the solutions. Films were both spin-coated and self assembles from solutions on a model oxidized single crystal silicon wafer, treated with HF. When coated from molecular solutions, the films tend to dewet on a time scale of minutes to hours. With increasing concentrations, above the critical micellar concentration of the ionomers in water/alcohol, stable films on the order of 200-500 angstroms were formed. While self-assembled films were found to be stable at temperatures close to Tg of the ionomer, spin-coated ones partially dewet. The surface structure obtained, exhibit periodicity on different length scales, depending on the concentration of the polymer in the solution from which the film was assembled. In the ultra dilute regime, micelles were detected at the solid interface. Films formed from dilute solutions exhibit fractal nature with a fractal dimension varying

  5. Measuring Stellar Rotation Periods with Kepler

    DEFF Research Database (Denmark)

    Nielsen, M. B.; Gizon, L.; Schunker, H.

    2013-01-01

    We measure rotation periods for 12151 stars in the Kepler field, based on photometric variability caused by stellar activity. Our analysis returns stable rotation periods over at least six out of eight quarters of Kepler data. This large sample of stars enables us to study rotation periods...

  6. Stable isotope analysis in primatology: a critical review.

    Science.gov (United States)

    Sandberg, Paul A; Loudon, James E; Sponheimer, Matt

    2012-11-01

    Stable isotope analysis has become an important tool in ecology over the last 25 years. A wealth of ecological information is stored in animal tissues in the relative abundances of the stable isotopes of several elements, particularly carbon and nitrogen, because these isotopes navigate through ecological processes in predictable ways. Stable carbon and nitrogen isotopes have been measured in most primate taxonomic groups and have yielded information about dietary content, dietary variability, and habitat use. Stable isotopes have recently proven useful for addressing more fine-grained questions about niche dynamics and anthropogenic effects on feeding ecology. Here, we discuss stable carbon and nitrogen isotope systematics and critically review the published stable carbon and nitrogen isotope data for modern primates with a focus on the problems and prospects for future stable isotope applications in primatology. © 2012 Wiley Periodicals, Inc.

  7. Stable isotope methodology and its application to nutrition and gastroenterology

    International Nuclear Information System (INIS)

    Klein, P.D.; Hachey, D.L.; Wong, W.W.; Abrams, S.A.

    1993-01-01

    This report describes the activities of the Stable Isotope Laboratory in its function as a core resource facility for stable isotope applications in human nutrition research. Three aspects are covered: Training of visitors, assessment of new instrumentation, and development of new methodology. The research achievements of the laboratory are indicated in the publications that appeared during this period. (author). 23 refs

  8. The Influence of Delayed Feedback Control on Stabilization of Periodic Orbits

    Directory of Open Access Journals (Sweden)

    V. G. Bogaevskaya

    2014-01-01

    Full Text Available In this paper we solve problems of stabilization of unstable cycle by the delay feedback. We study a model equation with qubic nonlinearity. In this case only one multiplicator is located outside a unit circle. Delay time is proportional to the cycle period. The D-partition of the parameter plane is obtained. The main result is analytically found conditions for parameters of delay control such that the initial cycle is stable. Also, we have found necessary and sufficient conditions of solvability of the stabilization problem. As a consequence, the problem of stablity of the Stuart–Landau equation periodic solution is completely solved.

  9. Periodic mesoporous silica gels

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, M.T.; Martin, J.E.; Odinek, J.G. [and others

    1996-06-01

    We have synthesized monolithic particulate gels of periodic mesoporous silica by adding tetramethoxysilane to a homogeneous alkaline micellar precursor solution. The gels exhibit 5 characteristic length scales over 4 orders of magnitude: fractal domains larger than the particle size (>500 nm), particles that are {approximately}150 to 500 nm in diameter, interparticle pores that are on the order of the particle size, a feature in the gas adsorption measurements that indicates pores {approximately}10-50 nm, and periodic hexagonal arrays of {approximately}3 nm channels within each particle. The wet gel monoliths exhibit calculated densities as low as {approximately}0.02 g/cc; the dried and calcined gels have bulk densities that range from {approximately}0.3-0.5 g/cc. The materials possess large interparticle ({approximately}1.0-2.3 cc/g) and intraparticle ({approximately}0.6 cc/g) porosities.

  10. Modulation instability analysis of modify unstable nonlinear schrodinger dynamical equation and its optical soliton solutions

    Directory of Open Access Journals (Sweden)

    Muhammad Arshad

    Full Text Available The nonlinear Schrödinger equations (NLSEs describe the promulgation of ultra-short pluse in optical fibers. The modify unstable nonlinear Schrödinger equation (mUNLSE is a universal equation of the class of nonlinear integrable systems in NLSEs, which governs certain instabilities of modulated wave-trains. This equation also describes the time evolution of disturbances in marginally stable or unstable media. In the current work, the aim is to investigate the mUNLSE analytically by utilizing proposed modified extended mapping method. New exact solutions are constructed in the different form such as exact dark soliton, exact bright soliton, bright-dark soliton, solitary wave, elliptic function in different form and periodic solutions of mUNLSE. Furthermore, we also present the formation conditions of the bright soliton and dark soliton of this equation. The modulation instability analysis is implemented to discuss the stability analysis of the attained solutions and the movement role of the waves is examined, which confirms that all constructed solutions are exact and stable. Keywords: Modify unstable nonlinear schrödinger equation, Modified extended mapping method, bright and dark solitons, Solitary wave solutions, Elliptic function solutions, periodic solutions

  11. Influence of horse stable environment on human airways

    Directory of Open Access Journals (Sweden)

    Pringle John

    2009-05-01

    Full Text Available Abstract Background Many people spend considerable amount of time each day in equine stable environments either as employees in the care and training of horses or in leisure activity. However, there are few studies available on how the stable environment affects human airways. This study examined in one horse stable qualitative differences in indoor air during winter and late summer conditions and assessed whether air quality was associated with clinically detectable respiratory signs or alterations to selected biomarkers of inflammation and lung function in stable personnel. Methods The horse stable environment and stable-workers (n = 13 in one stable were investigated three times; first in the winter, second in the interjacent late summer and the third time in the following winter stabling period. The stable measurements included levels of ammonia, hydrogen sulphide, total and respirable dust, airborne horse allergen, microorganisms, endotoxin and glucan. The stable-workers completed a questionnaire on respiratory symptoms, underwent nasal lavage with subsequent analysis of inflammation markers, and performed repeated measurements of pulmonary function. Results Measurements in the horse stable showed low organic dust levels and high horse allergen levels. Increased viable level of fungi in the air indicated a growing source in the stable. Air particle load as well as 1,3-β-glucan was higher at the two winter time-points, whereas endotoxin levels were higher at the summer time-point. Two stable-workers showed signs of bronchial obstruction with increased PEF-variability, increased inflammation biomarkers relating to reported allergy, cold or smoking and reported partly work-related symptoms. Furthermore, two other stable-workers reported work-related airway symptoms, of which one had doctor's diagnosed asthma which was well treated. Conclusion Biomarkers involved in the development of airway diseases have been studied in relation to

  12. Siemens IT solutions for power sector. PROFIT solutions

    International Nuclear Information System (INIS)

    Lunter, P.

    2004-01-01

    The cost reduction, flexibility and revenue increase, potential exploitation, productivity increase, and business opportunities exploitation - that is all what can be required in the races for the promonent positioning on the electricity power market. These requirements can be realized by the sophisticated IT solutions hand-tailored to the special requirements of the electric power producers and tradesmen. This approach makes it possible to achieve greater profit. Our solutions 'PROFIT Solutions', that are symbiosis of the most progressive information technologies and the power plant techniques of the company Siemens, satisfy submitted specifications in substantial measure. The system solutions 'PROFIT Solutions' comprise three solution groups: process, operation a business. The solutions of the group 'IT Process Solutions' increase flexibility and manoeuvrability of equipment, improve the efficiency and contribute to more economical operation of the power generation. Solutions 'IT Process Solutions' simplify and shorten the period of power cycles and conduce to higher labour productivity. Solutions group 'IT Process Solutions' approaches equipment to the market - supports the profit strategies, helps quickly and expertly to determine and predict hazards. The extension PROFIT Cockpit means the nuance to the solutions world 'PROFIT Solutions'. The survey about the whole installation is within reach at the simple touch of a button. It is possible to compile the total system part by part from single solutions 'PROFIT Solutions'. As a matter of fact all single parts can be interconnected with already existing solutions. Routines 'PROFIT Solutions' cooperate with all modern control systems. (author)

  13. Dynamical attraction to stable processes

    OpenAIRE

    Fisher, Albert M.; Talet, Marina

    2012-01-01

    We apply dynamical ideas within probability theory, proving an almost-sure invariance principle in log density for stable processes. The familiar scaling property (self-similarity) of the stable process has a stronger expression, that the scaling flow on Skorokhod path space is a Bernoulli flow. We prove that typical paths of a random walk with i.i.d. increments in the domain of attraction of a stable law can be paired with paths of a stable process so that, after applying a non-random regula...

  14. Stability of a novel corticosteroid nasal irrigation solution: betamethasone 17-valerate added to extemporaneously prepared nasal irrigation solutions.

    Science.gov (United States)

    Ong, Kheng Yong; Lim, Wei Ching; Ooi, Shing Ming; Loh, Zhi Hui; Kong, Ming Chai; Chan, Lai Wah; Heng, Paul Wan Sia

    2017-05-01

    There are no commercially available nasal irrigation solutions containing corticosteroids. Instead, such preparations are extemporaneously prepared by adding existing corticosteroid formulations to nasal irrigation solutions. The stability of the corticosteroid betamethasone 17-valerate (B17V), in nasal irrigation solutions of different compositions and pH and stored under different temperatures, was studied to determine the optimal choice of solution and storage conditions. Triplicate extemporaneous preparations made with B17V were prepared by adding a predetermined volume of B17V lotion to each nasal irrigation solution: normal saline (NS), sodium bicarbonate (NaHCO 3 ) powder dissolved in tap water, and a commercially available powder mixture (FLO Sinus Care Powder), dissolved in tap water or pre-boiled tap water. Preparations were stored at 30°C and 4°C. Sampling was carried out at 0, 1, 2, 6, and 24 hours. The concentrations of B17V and its degradation compound, betamethasone 21-valerate (B21V), were determined by high-performance liquid chromatography. Preparations stored at 30°C contained a lower amount of B17V and higher amount of B21V than those stored at 4°C. B17V stability in nasal irrigation solutions decreased in the following order: NS, FLO in fresh tap water, FLO in pre-boiled tap water, and NaHCO 3 . The degradation rate of B17V increased with higher storage temperature and higher pH. B17V is most stable when added to NS and least stable in NaHCO 3 solution. FLO solution prepared with either cooled boiled water or tap water is an alternative if administered immediately. Storage at 4°C can better preserve stability of B17V, over a period of 24 hours. © 2017 ARS-AAOA, LLC.

  15. Stable emulsions in extraction systems containing zirconium and silicic acid

    International Nuclear Information System (INIS)

    Sinegribova, O.A.; Chizhevskaya, S.V.; Kotenko, A.A.

    1989-01-01

    The effect of zirconium nitrate compound nature and silicic acid on the rate of emulsions stratification in extraction systems depending on the components concentration, solution acidity, its past history, is studied. It is stated that stable multinuclear zirconium compounds have an influence on formation of stable emulsions in systems containing silicic acid. On the basis of results of chemical analysis and properties of interphase precipitates, being part of stable emulsion, suppositions on mechanism of interaction of zirconium nitrate compounds with silicic acid β-form are made

  16. Periodic instantons and scattering amplitudes

    International Nuclear Information System (INIS)

    Khlebnikov, S.Yu.; Rubakov, V.A.; Tinyakov, P.G.

    1991-04-01

    We discuss the role of periodic euclidean solutions with two turning points and zero winding number (periodic instantons) in instanton induced processes below the sphaleron energy E sph . We find that the periodic instantons describe certain multiparticle scattering events leading to the transitions between topologically distinct vacua. Both the semiclassical amplitudes and inital and final states of these transitions are determined by the periodic instantons. Furthermore, the corresponding probabilities are maximal among all states of given energy. We show that at E ≤ E sph , the periodic instantons can be approximated by infinite chains of ordinary instantons and anti-instantons, and they naturally emerge as deformations of the zero energy instanton. In the framework of 2d abelian Higgs model and 4d electroweak theory we show, however, that there is not obvious relation between periodic instantons and two-particle scattering amplitudes. (orig.)

  17. Stable isotopes in Lithuanian bioarcheological material

    Science.gov (United States)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Schutkowski. "Diet and social status during the La Tène period in Bohemia: carbon and nitrogen stable isotope analysis of bone collagen from Kutná Hora-Karlov and Radovesice." Journal of Anthropological Archaeology 24.2 (2005): 135-147. Schutkowski, Holger, et al. "Diet, status and decomposition at Weingarten: trace element and isotope analyses on early mediaeval skeletal material." Journal of Archaeological Science 26.6 (1999): 675-685. Zernitskaya, Valentina, et al. "Vegetation pattern and sedimentation changes in the context of the Lateglacial climatic events: Case study of Staroje Lake (Eastern Belarus)." Quaternary International (2014).

  18. Stable colloids in molten inorganic salts

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao; Dasbiswas, Kinjal; Ludwig, Nicholas B.; Han, Gang; Lee, Byeongdu; Vaikuntanathan, Suri; Talapin, Dmitri V.

    2017-02-15

    A colloidal solution is a homogeneous dispersion of particles or droplets of one phase (solute) in a second, typically liquid, phase (solvent). Colloids are ubiquitous in biological, chemical and technological processes1, 2, homogenizing highly dissimilar constituents. To stabilize a colloidal system against coalescence and aggregation, the surface of each solute particle is engineered to impose repulsive forces strong enough to overpower van der Waals attraction and keep the particles separated from each other2. Electrostatic stabilization3, 4 of charged solutes works well in solvents with high dielectric constants, such as water (dielectric constant of 80). In contrast, colloidal stabilization in solvents with low polarity, such as hexane (dielectric constant of about 2), can be achieved by decorating the surface of each particle of the solute with molecules (surfactants) containing flexible, brush-like chains2, 5. Here we report a class of colloidal systems in which solute particles (including metals, semiconductors and magnetic materials) form stable colloids in various molten inorganic salts. The stability of such colloids cannot be explained by traditional electrostatic and steric mechanisms. Screening of many solute–solvent combinations shows that colloidal stability can be traced to the strength of chemical bonding at the solute–solvent interface. Theoretical analysis and molecular dynamics modelling suggest that a layer of surface-bound solvent ions produces long-ranged charge-density oscillations in the molten salt around solute particles, preventing their aggregation. Colloids composed of inorganic particles in inorganic melts offer opportunities for introducing colloidal techniques to solid-state science and engineering applications.

  19. Synthetic chemistry with periodic mesostructures at high pressure.

    Science.gov (United States)

    Mandal, Manik; Landskron, Kai

    2013-11-19

    Over the last two decades, researchers have studied extensively the synthesis of mesostructured materials, which could be useful for drug delivery, catalytic cracking of petroleum, or reinforced plastics, among other applications. However, until very recently researchers used only temperature as a thermodynamic variable for synthesis, completely neglecting pressure. In this Account, we show how pressure can affect the synthetic chemistry of periodic mesoporous structures with desirable effects. In its simplest application, pressure can crystallize the pore walls of periodic mesoporous silicas, which are difficult to crystallize otherwise. The motivation for the synthesis of periodic mesoporous silica materials (with pore sizes from 2 to 50 nm) 20 years ago was to replace the microporous zeolites (which have pore sizes of amorphous nature of the mesoporous materials' channel walls. To address this problem, we developed the concept of "nanocasting at high pressure". Through this approach, we produced hitherto-unavailable, periodic mesostructured silicas with crystalline pore walls. In nanocasting, we compress a periodic mesostructured composite (e.g. a periodic mesoporous silica with carbon-filled pores) and subsequently heat it to induce the selective crystallization of one of the two phases. We attain the necessary high pressure for synthesis using piston-cylinder and multianvil apparatuses. Using periodic mesostructured silica/carbon nanocomposites as starting material, we have produced periodic mesoporous coesite and periodic mesoporous quartz. The quartz material is highly stable under harsh hydrothermal conditions (800°C in pure steam), verifying that crystallinity in the channel walls of periodic mesoporous silicas increases their hydrothermal stability. Even without including the carbon phase in the silica pores, we could obtain mesoporous coesite materials. We found similar behavior for periodic mesoporous carbons, which convert into transparent, mesoporous

  20. Numerical solution of the Maxwell-Vlasov equations in the periodic regime. Application to the study of isotope separation by ion cyclotron resonance; Resolution numerique des equations de Maxwell-Vlasov en regime periodique. Application a l'etude de la separation isotopique par resonance cyclotron ionique

    Energy Technology Data Exchange (ETDEWEB)

    Omnes, P

    1999-01-25

    This work is dedicated to the study of the behaviour of a magnetic confined plasma that is excited by a purely sinusoidal electric current delivered by an antenna. The response of the electrons to the electromagnetic field is considered as linear,whereas the ions of the plasma are represented by a non-relativistic Vlasov equation. In order to avoid transients, the coupled Maxwell-Vlasov equations are solved in a periodic mode and in a bounded domain. An equivalent electric conductivity tensor has been defined, this tensor is a linear operator that links the electric current generated by the movement of the particles to the electromagnetic field. Theoretical considerations can assure the existence and uniqueness of a periodical solution to Vlasov equations and of a solution to Maxwell equations in harmonic mode. The system of equations is periodical and has been solved by using an iterative method. The application of this method to the simulation of a isotopic separation device based on ionic cyclotron resonance has shown that the convergence is reached in a few iterations and that the solution is valid. Furthermore a method based on a finite-volume formulation of Maxwell equations in the time domain is presented. 2 new variables are defined in order to better take into account the Gauss' law and the conservation of the magnetic flux, the new system is still hyperbolic. The parallelization of the process has been successfully realized. (A.C.)

  1. The production of stable isotopes in Spain

    Energy Technology Data Exchange (ETDEWEB)

    Urgel, M.; Iglesias, J.; Casas, J.; Saviron, J. M.; Quintanilla, M.

    1965-07-01

    The activities developed in the field of the production of stable isotopes by means of ion-exchange chromatography and thermal diffusion techniques are reported. The first method was used to study the separation of the nitrogen and boron isotopes, whereby the separation factor was determined by the break through method. Values ranging from 1,028 to 1,022 were obtained for the separation factor of nitrogen by using ammonium hydroxide solutions while the corresponding values as obtained for boron amounted to 1,035-1,027 using boric acid solutions. Using ammonium chloride or acetate and sodium borate, respectively, resulted in the obtention of values for the separation factor approaching unity. The isotopic separation has been carried out according to the method of development by displacement. The separation of the isotopes of the noble gases, oxygen, nitrogen and carbon has been accomplished resorting to the method of thermal diffusion. (Author) 16 refs.

  2. The production of stable isotopes in Spain

    International Nuclear Information System (INIS)

    Urgel, M.; Iglesias, J.; Casas, J.; Saviron, J. M.; Quintanilla, M.

    1965-01-01

    The activities developed in the field of the production of stable isotopes by means of ion-exchange chromatography and thermal diffusion techniques are reported. The first method was used to study the separation of the nitrogen and boron isotopes, whereby the separation factor was determined by the break through method. Values ranging from 1,028 to 1,022 were obtained for the separation factor of nitrogen by using ammonium hydroxide solutions while the corresponding values as obtained for boron amounted to 1,035-1,027 using boric acid solutions. Using ammonium chloride or acetate and sodium borate, respectively, resulted in the obtention of values for the separation factor approaching unity. The isotopic separation has been carried out according to the method of development by displacement. The separation of the isotopes of the noble gases, oxygen, nitrogen and carbon has been accomplished resorting to the method of thermal diffusion. (Author) 16 refs

  3. Localized solutions for a nonlocal discrete NLS equation

    Energy Technology Data Exchange (ETDEWEB)

    Ben, Roberto I. [Instituto de Desarrollo Humano, Universidad Nacional de General Sarmiento, J.M. Gutiérrez 1150, 1613 Los Polvorines (Argentina); Cisneros Ake, Luís [Department of Mathematics, ESFM, Instituto Politécnico Nacional, Unidad Profesional Adolfo López Mateos Edificio 9, 07738 México D.F. (Mexico); Minzoni, A.A. [Depto. Matemáticas y Mecánica, I.I.M.A.S.-U.N.A.M., Apdo. Postal 20-726, 01000 México D.F. (Mexico); Panayotaros, Panayotis, E-mail: panos@mym.iimas.unam.mx [Depto. Matemáticas y Mecánica, I.I.M.A.S.-U.N.A.M., Apdo. Postal 20-726, 01000 México D.F. (Mexico)

    2015-09-04

    We study spatially localized time-periodic solutions of breather type for a cubic discrete NLS equation with a nonlocal nonlinearity that models light propagation in a liquid crystal waveguide array. We show the existence of breather solutions in the limit where both linear and nonlinear intersite couplings vanish, and in the limit where the linear coupling vanishes with arbitrary nonlinear intersite coupling. Breathers of this nonlocal regime exhibit some interesting features that depart from what is seen in the NLS breathers with power nonlinearity. One property we see theoretically is the presence of higher amplitude at interfaces between sites with zero and nonzero amplitude in the vanishing linear coupling limit. A numerical study also suggests the presence of internal modes of orbitally stable localized modes. - Highlights: • Show existence of spatially localized solutions in nonlocal discrete NLS model. • Study spatial properties of localized solutions for arbitrary nonlinear nonlocal coupling. • Present numerical evidence that nonlocality leads to internal modes around stable breathers. • Present theoretical and numerical evidence for amplitude maxima at interfaces.

  4. WORKSHOP: Stable particle motion

    International Nuclear Information System (INIS)

    Ruggiero, Alessandro G.

    1993-01-01

    Full text: Particle beam stability is crucial to any accelerator or collider, particularly big ones, such as Brookhaven's RHIC heavy ion collider and the larger SSC and LHC proton collider schemes. A workshop on the Stability of Particle Motion in Storage Rings held at Brookhaven in October dealt with the important issue of determining the short- and long-term stability of single particle motion in hadron storage rings and colliders, and explored new methods for ensuring it. In the quest for realistic environments, the imperfections of superconducting magnets and the effects of field modulation and noise were taken into account. The workshop was divided into three study groups: Short-Term Stability in storage rings, including chromatic and geometric effects and correction strategies; Long-Term Stability, including modulation and random noise effects and slow varying effects; and Methods for determining the stability of particle motion. The first two were run in parallel, but the third was attended by everyone. Each group considered analytical, computational and experimental methods, reviewing work done so far, comparing results and approaches and underlining outstanding issues. By resolving conflicts, it was possible to identify problems of common interest. The workshop reaffirmed the validity of methods proposed several years ago. Major breakthroughs have been in the rapid improvement of computer capacity and speed, in the development of more sophisticated mathematical packages, and in the introduction of more powerful analytic approaches. In a typical storage ring, a particle may be required to circulate for about a billion revolutions. While ten years ago it was only possible to predict accurately stability over about a thousand revolutions, it is now possible to predict over as many as one million turns. If this trend continues, in ten years it could become feasible to predict particle stability over the entire storage period. About ninety participants

  5. Stable isotope separation

    International Nuclear Information System (INIS)

    Botter, F.; Molinari, Ph.; Dirian, G.

    1964-01-01

    circulates. Studies are going forward to increase the separation factor of the cascade by using an auxiliary gas. Isotopic Exchange: A series of experiments has been performed to determine the isotopic separation factor between a lithium amalgam and an organic solvent containing a lithium salt. The various parameters which may enter into this exchange were studied: the influence of the type of solvent (the two solvents used were dimethylformamide and tetrahydrofurane), of the temperature, of the concentration and of the nature of the associated halogen. Solutions of Li metal and liquid NH 3 were studied also. A number of tests were carried out to see whether there was a difference between the isotopic compositions of the Li present in the two liquid layers obtained by the dissolution of Li metal in ammonia. No difference was observed between the Li isotopic ratios in the two phases. This was also true in the case of a layer of of Li in liquid NH 3 and a layer of Li I in a similar solvent. Electromigration: The method of counter current electro Migration in fused salts is a powerful isotopic enrichment technique. It can be used successfully to separate the isotopes of elements with strongly metallic character. In the case of alkalis, small quantities of isotopically pure 7 Li have been obtained, while the enrichment factors obtained for potassium are of the order of 10. With regard to the alkaline earths, it has been possible to produce small quantities of calcium enriched 5 times in 46 Ca. However considerable technological difficulties rise up in the way of production on a semi-industrial scale. (authors) [fr

  6. Viscosity Solution

    OpenAIRE

    Camilli, Fabio; Prados, Emmanuel

    2011-01-01

    International audience; Viscosity solution is a notion of weak solution for a class of partial differential equations of Hamilton-Jacobi type. The range of applications of the notions of viscosity solution and Hamilton-Jacobi equations is enormous, including common class of partial differential equations such as evolutive problems and problems with boundary conditions, equations arising in optimal control theory, differential games, second-order equations arising in stochastic optimal control...

  7. 77 FR 60113 - Acceptance of Public Submissions Regarding the Study of Stable Value Contracts

    Science.gov (United States)

    2012-10-02

    ...; File No. S7-32-11] Acceptance of Public Submissions Regarding the Study of Stable Value Contracts...'') are reopening the comment period for a study to determine whether stable value contracts (``SVCs... method. ``Stable Value Contract Study'' must be in the subject field of responses submitted via email...

  8. Elastic Stable Intramedullary Nailing for Treatment of Pediatric Tibial Fractures

    OpenAIRE

    Sandeep Gurung; Dipendra KC; Roshni Khatri

    2016-01-01

    Introduction: Tibia fractures in the skeletally immature patient can usually be treated with above knee cast or patellar tendon bearing cast. The purpose of our study was to evaluate epidemiology and outcome of Elastic stable intramedullary nailing fixation of pediatric tibial shaft fractures treated at our institution. Methods: Over a period of one year, fifty pediatric patients of tibial shaft fractures, with average age of 9.68 yr (SD=2.37), were treated with elastic stable intramedul...

  9. Shelf-Stable Food Safety

    Science.gov (United States)

    ... is an MRE? Is an MRE shelf stable? What foods are packaged in retort packages? What is aseptic ... type of package is used for aseptic processing? What foods are packaged in aseptic packages? Can I microwave ...

  10. Aggressive Fibromatosis: Evidence for a Stable Phase

    Directory of Open Access Journals (Sweden)

    Gillian Mitchell

    1998-01-01

    Full Text Available Purpose. Aggressive fibromatosis (AF is an uncommon locally infiltrating benign disease of soft tissue for which treatment comprises complete surgical resection. Radiotherapy can be given postoperatively if the margin is incompletely resected. If the tumour is inoperable radiotherapy provides an alternative treatment. Hormone therapy and cytotoxic chemotherapy have also been used for unresectable or recurrent disease. All treatment modalities carry an associated morbidity. We believe that the natural history of aggressive fibromatosis may include a period of stable disease without progression, during which time, treatment is not always necessary.

  11. Pharmaceuticals labelled with stable isotopes

    International Nuclear Information System (INIS)

    Krumbiegel, P.

    1986-11-01

    The relatively new field of pharmaceuticals labelled with stable isotopes is reviewed. Scientific, juridical, and ethical questions are discussed concerning the application of these pharmaceuticals in human medicine. 13 C, 15 N, and 2 H are the stable isotopes mainly utilized in metabolic function tests. Methodical contributions are given to the application of 2 H, 13 C, and 15 N pharmaceuticals showing new aspects and different states of development in the field under discussion. (author)

  12. Stable isotope research pool inventory

    International Nuclear Information System (INIS)

    1984-03-01

    This report contains a listing of electromagnetically separated stable isotopes which are available at the Oak Ridge National Laboratory for distribution for nondestructive research use on a loan basis. This inventory includes all samples of stable isotopes in the Research Materials Collection and does not designate whether a sample is out on loan or is in reprocessing. For some of the high abundance naturally occurring isotopes, larger amounts can be made available; for example, Ca-40 and Fe-56

  13. Numerical Simulation of Cylindrical Solitary Waves in Periodic Media

    KAUST Repository

    Quezada de Luna, Manuel

    2013-07-14

    We study the behavior of nonlinear waves in a two-dimensional medium with density and stress relation that vary periodically in space. Efficient approximate Riemann solvers are developed for the corresponding variable-coefficient first-order hyperbolic system. We present direct numerical simulations of this multiscale problem, focused on the propagation of a single localized perturbation in media with strongly varying impedance. For the conditions studied, we find little evidence of shock formation. Instead, solutions consist primarily of solitary waves. These solitary waves are observed to be stable over long times and to interact in a manner approximately like solitons. The system considered has no dispersive terms; these solitary waves arise due to the material heterogeneity, which leads to strong reflections and effective dispersion.

  14. Dysmenorrhea: Painful Periods

    Science.gov (United States)

    ... Search FAQs Dysmenorrhea: Painful Periods Page Navigation ▼ ACOG Pregnancy Book Dysmenorrhea: Painful Periods Patient Education FAQs Dysmenorrhea: Painful Periods Patient Education Pamphlets - Spanish ...

  15. Synthesis and characterization of stable aqueous dispersions of ...

    Indian Academy of Sciences (India)

    2.2b Preparation of aqueous graphene dispersion from graphite oxide: One hundred milligrams of the above pre- pared graphite oxide was dispersed in 100 ml of MilliQ water followed by sonication for 1 h. A clear brown coloured solution was obtained, which is the stable dispersion of GO in water. Subsequently, the pH of ...

  16. Some Stiffly Stable Second Derivative Continuous Linear Multistep ...

    African Journals Online (AJOL)

    Dr Grace Nwachukwu

    Based on Gear's fixed step size backward differentiation methods, Gear (1968), second derivative continuous ... whose solution is stiff, let us consider the family of hybrid second derivative continuous linear multistep methods. ( ) ...... The Numerical Integration of stiff Systems of ODEs using Stiffly Stable Continuous Second.

  17. Linear operator inequalities for strongly stable weakly regular linear systems

    NARCIS (Netherlands)

    Curtain, RF

    2001-01-01

    We consider the question of the existence of solutions to certain linear operator inequalities (Lur'e equations) for strongly stable, weakly regular linear systems with generating operators A, B, C, 0. These operator inequalities are related to the spectral factorization of an associated Popov

  18. Stable solitons of quadratic ginzburg-landau equations

    Science.gov (United States)

    Crasovan; Malomed; Mihalache; Mazilu; Lederer

    2000-07-01

    We present a physical model based on coupled Ginzburg-Landau equations that supports stable temporal solitary-wave pulses. The system consists of two parallel-coupled cores, one having a quadratic nonlinearity, the other one being effectively linear. The former core is active, with bandwidth-limited amplification built into it, while the latter core has only losses. Parameters of the model can be easily selected so that the zero background is stable. The model has nongeneric exact analytical solutions in the form of solitary pulses ("dissipative solitons"). Direct numerical simulations, using these exact solutions as initial configurations, show that they are unstable; however, the evolution initiated by the exact unstable solitons ends up with nontrivial stable localized pulses, which are very robust attractors. Direct simulations also demonstrate that the presence of group-velocity mismatch (walkoff) between the two harmonics in the active core makes the pulses move at a constant velocity, but does not destabilize them.

  19. Sensitive, Fast, and Stable Perovskite Photodetectors Exploiting Interface Engineering

    KAUST Repository

    Sutherland, Brandon R.

    2015-08-19

    © 2015 American Chemical Society. Organometallic halide perovskites are a class of solution-processed semiconductors exhibiting remarkable optoelectronic properties. They have seen rapid strides toward enabling efficient third-generation solar cell technologies. Here, we report the first material-tailoring of TiO2/perovskite/spiro-OMeTAD junction-based photodiodes toward applications in photodetection, a field in need of fast, sensitive, low-cost, spectrally tunable materials that offer facile integration across a broad range of substrates. We report photodetection that exhibits 1 μs temporal response, and we showcase stable operation in the detection of over 7 billion transient light pulses through a continuous pulsed-illumination period. The perovskite diode photodetector has a peak responsivity approaching 0.4 A W-1 at 600 nm wavelength, which is superior to red light detection in crystalline silicon photodiodes used in commercial image sensors. Only by developing a composite Al2O3/PCBM front contact interface layer were we able to stabilize device operation in air, reduce dark current, and enhance the responsivity in the low-bias regime to achieve an experimentally measured specific detectivity of 1012 Jones.

  20. Solution preparation

    International Nuclear Information System (INIS)

    Seitz, M.G.

    1982-01-01

    Reviewed in this statement are methods of preparing solutions to be used in laboratory experiments to examine technical issues related to the safe disposal of nuclear waste from power generation. Each approach currently used to prepare solutions has advantages and any one approach may be preferred over the others in particular situations, depending upon the goals of the experimental program. These advantages are highlighted herein for three approaches to solution preparation that are currently used most in studies of nuclear waste disposal. Discussion of the disadvantages of each approach is presented to help a user select a preparation method for his particular studies. Also presented in this statement are general observations regarding solution preparation. These observations are used as examples of the types of concerns that need to be addressed regarding solution preparation. As shown by these examples, prior to experimentation or chemical analyses, laboratory techniques based on scientific knowledge of solutions can be applied to solutions, often resulting in great improvement in the usefulness of results

  1. Contribution to harmonic balance calculations of self-sustained periodic oscillations with focus on single-reed instruments.

    Science.gov (United States)

    Farner, Snorre; Vergez, Christophe; Kergomard, Jean; Lizée, Aude

    2006-03-01

    The harmonic balance method (HBM) was originally developed for finding periodic solutions of electronical and mechanical systems under a periodic force, but has been adapted to self-sustained musical instruments. Unlike time-domain methods, this frequency-domain method does not capture transients and so is not adapted for sound synthesis. However, its independence of time makes it very useful for studying any periodic solution, whether stable or unstable, without care of particular initial conditions in time. A computer program for solving general problems involving nonlinearly coupled exciter and resonator, HARMBAL, has been developed based on the HBM. The method as well as convergence improvements and continuation facilities are thoroughly presented and discussed in the present paper. Applications of the method are demonstrated, especially on problems with severe difficulties of convergence: the Helmholtz motion (square signals) of single-reed instruments when no losses are taken into account, the reed being modeled as a simple spring.

  2. The nature of stable insomnia phenotypes.

    Science.gov (United States)

    Pillai, Vivek; Roth, Thomas; Drake, Christopher L

    2015-01-01

    We examined the 1-y stability of four insomnia symptom profiles: sleep onset insomnia; sleep maintenance insomnia; combined onset and maintenance insomnia; and neither criterion (i.e., insomnia cases that do not meet quantitative thresholds for onset or maintenance problems). Insomnia cases that exhibited the same symptom profile over a 1-y period were considered to be phenotypes, and were compared in terms of clinical and demographic characteristics. Longitudinal. Urban, community-based. Nine hundred fifty-four adults with Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition based current insomnia (46.6 ± 12.6 y; 69.4% female). None. At baseline, participants were divided into four symptom profile groups based on quantitative criteria. Follow-up assessment 1 y later revealed that approximately 60% of participants retained the same symptom profile, and were hence judged to be phenotypes. Stability varied significantly by phenotype, such that sleep onset insomnia (SOI) was the least stable (42%), whereas combined insomnia (CI) was the most stable (69%). Baseline symptom groups (cross-sectionally defined) differed significantly across various clinical indices, including daytime impairment, depression, and anxiety. Importantly, however, a comparison of stable phenotypes (longitudinally defined) did not reveal any differences in impairment or comorbid psychopathology. Another interesting finding was that whereas all other insomnia phenotypes showed evidence of an elevated wake drive both at night and during the day, the 'neither criterion' phenotype did not; this latter phenotype exhibited significantly higher daytime sleepiness despite subthreshold onset and maintenance difficulties. By adopting a stringent, stability-based definition, this study offers timely and important data on the longitudinal trajectory of specific insomnia phenotypes. With the exception of daytime sleepiness, few clinical differences are apparent across stable phenotypes.

  3. Stable Boundary Layer Education (STABLE) Final Campaign Summary

    Energy Technology Data Exchange (ETDEWEB)

    Turner, David D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-03-01

    The properties of, and the processes that occur in, the nocturnal stable boundary layer are not well understood, making it difficult to represent adequately in numerical models. The nocturnal boundary layer often is characterized by a temperature inversion and, in the Southern Great Plains region, a low-level jet. To advance our understanding of the nocturnal stable boundary layer, high temporal and vertical resolution data on the temperature and wind properties are needed, along with both large-eddy simulation and cloud-resolving modeling.

  4. Periodic and quasiperiodic revivals in periodically driven interacting quantum systems

    Science.gov (United States)

    Luitz, David J.; Lazarides, Achilleas; Bar Lev, Yevgeny

    2018-01-01

    Recently it has been shown that interparticle interactions generically destroy dynamical localization in periodically driven systems, resulting in diffusive transport and heating. In this Rapid Communication we rigorously construct a family of interacting driven systems which are dynamically localized and effectively decoupled from the external driving potential. We show that these systems exhibit tunable periodic or quasiperiodic revivals of the many-body wave function and thus of all physical observables. By numerically examining spinless fermions on a one-dimensional lattice we show that the analytically obtained revivals of such systems remain stable for finite systems with open boundary conditions while having a finite lifetime in the presence of static spatial disorder. We find this lifetime to be inversely proportional to the disorder strength.

  5. Multipolar Solutions

    OpenAIRE

    Quevedo, Hernando

    2012-01-01

    A class of exact solutions of the Einstein-Maxwell equations is presented which contains infinite sets of gravitoelectric, gravitomagnetic and electromagnetic multipole moments. The multipolar structure of the solutions indicates that they can be used to describe the exterior gravitational field of an arbitrarily rotating mass distribution endowed with an electromagnetic field. The presence of gravitational multipoles completely changes the structure of the spacetime because of the appearance...

  6. Co-periodic stability of periodic waves in some Hamiltonian PDEs

    Science.gov (United States)

    Benzoni-Gavage, S.; Mietka, C.; Rodrigues, L. M.

    2016-10-01

    The stability of periodic traveling wave solutions to dispersive PDEs with respect to ‘arbitrary’ perturbations is still widely open. The focus is put here on stability with respect to perturbations of the same period as the wave, for KdV-like systems of one-dimensional Hamiltonian PDEs. Stability criteria are derived and investigated first in a general abstract framework, and then applied to three basic examples that are very closely related, and ubiquitous in mathematical physics, namely, a quasilinear version of the generalized Korteweg-de Vries equation (qKdV), and the Euler-Korteweg system in both Eulerian coordinates (EKE) and in mass Lagrangian coordinates (EKL). Those criteria consist of a necessary condition for spectral stability, and of a sufficient condition for orbital stability. Both are expressed in terms of a single function, the abbreviated action integral along the orbits of waves in the phase plane, which is the counterpart of the solitary waves moment of instability introduced by Boussinesq. Regarding solitary waves, the celebrated Grillakis-Shatah-Strauss stability criteria amount to looking for the sign of the second derivative of the moment of instability with respect to the wave speed. For periodic waves, the most striking results obtained here can be summarized as: an odd value for the difference between N—the size of the PDE system—and the negative signature of the Hessian of the action implies spectral instability, whereas a negative signature of the same Hessian being equal to N implies orbital stability. Since these stability criteria are merely encoded by the negative signature of matrices, they can at least be checked numerically. Various numerical experiments are presented, which clearly discriminate between stable cases and unstable cases for (qKdV), (EKE) and (EKL).

  7. Stability and instability of stationary solutions for sublinear parabolic equations

    Science.gov (United States)

    Kajikiya, Ryuji

    2018-01-01

    In the present paper, we study the initial boundary value problem of the sublinear parabolic equation. We prove the existence of solutions and investigate the stability and instability of stationary solutions. We show that a unique positive and a unique negative stationary solutions are exponentially stable and give the exact exponent. We prove that small stationary solutions are unstable. For one space dimensional autonomous equations, we elucidate the structure of stationary solutions and study the stability of all stationary solutions.

  8. Analytic solutions of nonlinear Cournot duopoly game

    Directory of Open Access Journals (Sweden)

    Akio Matsumoto

    2005-01-01

    Full Text Available We construct a Cournot duopoly model with production externality in which reaction functions are unimodal. We consider the case of a Cournot model which has a stable equilibrium point. Then we show the existence of analytic solutions of the model. Moreover, we seek general solutions of the model in the form of nonlinear second-order difference equation.

  9. Hypochlorite solution for root canal irrigation that lacks a chlorinated odor.

    Science.gov (United States)

    Vajrabhaya, La-Ongthong; Sangalungkarn, Vanida; Srisatjaluk, Ratchapin; Korsuwannawong, Suwanna; Phruksaniyom, Chareerut

    2017-01-01

    This is an in vitro study to develop a formulation of a hypochlorite solution for root canal irrigation that lacks a chlorinated odor. The antibacterial effect, tissue dissolution efficacy, and the cytotoxicity of the solution were assessed in cell culture and were compared with those of commercial sodium hypochlorite (NaOCl) solutions. Trichloroisocyanuric acid (TCA) was used as the source of hypochlorite ions in solution. All required properties of the NaOCl irrigant were evaluated and compared with those of original 2.5% NaOCl solutions currently in use. Our results revealed that a TCA 3.5% + 1/6 Buffer-1 solution passed the short-term stability test. Moreover, no odor of chlorine gas was detected by three independent observers. The hypochlorite ion content and pH were stable over an incubation period of 4 weeks. The new solution did not differ from commercial products in terms of the dissolution property on bovine pulpal tissue ( P > 0.05). Moreover, the antibacterial effect of this solution on Enterococcus faecalis did not differ from that of the commercial products ( P > 0.05). In addition, our biocompatibility analysis demonstrated no difference among the tested solutions ( P > 0.05). According to the results of all properties tested, TCA 3.5% + 1/6 Buffer-1 could be considered an option for NaOCl irrigation with the benefit of no detectable chlorine odor.

  10. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  11. Radiation-stable polyolefin compositions

    International Nuclear Information System (INIS)

    Rekers, J.W.

    1986-01-01

    This invention relates to compositions of olefinic polymers suitable for high energy radiation treatment. In particular, the invention relates to olefinic polymer compositions that are stable to sterilizing dosages of high energy radiation such as a gamma radiation. Stabilizers are described that include benzhydrol and benzhydrol derivatives; these stabilizers may be used alone or in combination with secondary antioxidants or synergists

  12. Monitoring of stable glaucoma patients

    NARCIS (Netherlands)

    K.M. Holtzer-Goor (Kim); N.S. Klazinga (Niek); M.A. Koopmanschap (Marc); H.G. Lemij (Hans); T. Plochg; E. van Sprundel (Esther)

    2010-01-01

    textabstractA high workload for ophthalmologists and long waiting lists for patients challenge the organization of ophthalmic care. Tasks that require less specialized skills, like the monitoring of stable (well controlled) glaucoma patients could be substituted from ophthalmologists to other

  13. Delivery of vitamins E and C from parenteral alimentation solution.

    Science.gov (United States)

    Shenai, J P; Borum, P R; Duke, E A

    1982-01-01

    We have previously shown that substantial losses of fat-soluble (FS) vitamin A from parenteral alimentation solution occur due to adsorption in the intravenous tubing and photodegradation in the bottle. This study assessed the delivery of other vitamins, viz, FS vitamin E and water-soluble (WS) vitamin C, from parenteral alimentation solution. The solution containing 2.0 ml/L of an aqueous multivitamin infusion was infused at a constant rate of 10 ml/h using a standard intravenous administration set. Multiple aliquots of the solution from the bottle and the effluent obtained sequentially in a 24-h period were analyzed for concentrations of vitamins E and C. Both vitamins remained relatively stable in the bottle. A significant amount (12%) of vitamin E was lost in the intravenous tubing. No losses of vitamin C were incurred in the intravenous tubing. The data suggest that delivery of FS vitamin E from parenteral alimentation solutions is less than optimum because of adsorptive losses. Similar losses are not encountered with WS vitamin C.

  14. Coexistence of collapse and stable spatiotemporal solitons in multimode fibers

    Science.gov (United States)

    Shtyrina, Olga V.; Fedoruk, Mikhail P.; Kivshar, Yuri S.; Turitsyn, Sergei K.

    2018-01-01

    We analyze spatiotemporal solitons in multimode optical fibers and demonstrate the existence of stable solitons, in a sharp contrast to earlier predictions of collapse of multidimensional solitons in three-dimensional media. We discuss the coexistence of blow-up solutions and collapse stabilization by a low-dimensional external potential in graded-index media, and also predict the existence of stable higher-order nonlinear waves such as dipole-mode spatiotemporal solitons. To support the main conclusions of our numerical studies we employ a variational approach and derive analytically the stability criterion for input powers for the collapse stabilization.

  15. Absent menstrual periods - secondary

    Science.gov (United States)

    Amenorrhea - secondary; No periods - secondary; Absent periods - secondary; Absent menses - secondary; Absence of periods - secondary ... Secondary amenorrhea can occur due to natural changes in the body. For example, the most common cause of secondary ...

  16. Highly stable organic polymer field-effect transistor sensor for selective detection in the marine environment

    Science.gov (United States)

    Knopfmacher, Oren; Hammock, Mallory L.; Appleton, Anthony L.; Schwartz, Gregor; Mei, Jianguo; Lei, Ting; Pei, Jian; Bao, Zhenan

    2014-01-01

    In recent decades, the susceptibility to degradation in both ambient and aqueous environments has prevented organic electronics from gaining rapid traction for sensing applications. Here we report an organic field-effect transistor sensor that overcomes this barrier using a solution-processable isoindigo-based polymer semiconductor. More importantly, these organic field-effect transistor sensors are stable in both freshwater and seawater environments over extended periods of time. The organic field-effect transistor sensors are further capable of selectively sensing heavy-metal ions in seawater. This discovery has potential for inexpensive, ink-jet printed, and large-scale environmental monitoring devices that can be deployed in areas once thought of as beyond the scope of organic materials.

  17. Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

    Science.gov (United States)

    Kumar, Nikhil; Upadhyay, Lata Sheo Bachan

    2016-11-01

    A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month

  18. Introducing fecal stable isotope analysis in primate weaning studies.

    Science.gov (United States)

    Reitsema, Laurie J

    2012-10-01

    This research investigates the potential of a new, noninvasive method for determining age of weaning among primates using stable carbon and nitrogen isotope ratios in feces. Analysis of stable isotope ratios in body tissues is a well-established method in archeology and ecology for reconstructing diet. This is the first study to investigate weaning in primates using fecal stable isotope ratios. Diets of a single François' langur (Trachypithecus francoisi) mother-infant pair at the Toledo Zoo are reconstructed using this technique to track changes in infant suckling behavior over the weaning period. Stable isotope ratios in feces are sampled instead of more traditional samples such as bone or hair to enable daily, noninvasive snapshots of weaning status. Isotopic assessments of weaning status are compared to visual assessments to identify any discordance between the two. Three measurements documented the transition from breast milk to solid foods: stable carbon isotope ratios (δ(13)C), stable nitrogen isotope ratios (δ(15)N), and nitrogen content of feces (%N). It appears that solid foods were introduced at approximately 2 months of infant age, but that nursing continued into the 12th month, when sample collection ceased. Stable isotope data exposed a much longer weaning period than what was expected based on previously published data for captive langurs, and clarified visual estimates of weaning status. This reflects the method's sensitivity to suckling at night and ability to distinguish actual nursing from comfort nursing. After testing this method with zoo animals, it can readily be applied among wild populations. An isotopic approach to weaning provides a new, accurate, and biologically meaningful assessment of interbirth intervals, and facilitates a better understanding of mother-infant interactions. Both of these outcomes are critical for developing successful conservation strategies for captive and wild primates. © 2012 Wiley Periodicals, Inc.

  19. The stable nonequilibrium state of bicarbonate aqueous systems

    Science.gov (United States)

    Voeikov, V. L.; Vilenskaya, N. D.; Ha, Do Minh; Malyshenko, S. I.; Buravleva, E. V.; Yablonskaya, O. I.; Timofeev, K. N.

    2012-09-01

    Data obtained by electron paramagnetic resonance (EPR) and chemiluminescence analysis indicate that in aqueous solutions of bicarbonates, superoxide radical and other reactive oxygen species (ROS) are constantly produced. The stationary level of the superoxide radical is found to increase when a solution is illuminated. Reactions involving ROS are shown to be accompanied by the generation of electron excitation energy, keeping bicarbonate solutions in a stable nonequilibrium state. The system can emit part of this energy. Variations in emitting activity are found to correlate with variations in the cosmophysical factors. The emitting activity of solutions is found to vary in the presence of low and ultralow concentrations of hydrated fullerenes. It is noted that the phenomenon of spontaneous charge separation in aqueous systems (G. H. Pollack) could play a role in maintaining a stable nonequilibrium state in bicarbonate systems where the reactions with ROS participation are catalyzed by forms of carbonate. It is concluded that the abovementioned properties of bicarbonate aqueous systems most likely keep living matter whose structural basis is formed by these systems in a stable excited state, thereby making it highly sensitive to the action of external factors with low and ultralow intensities.

  20. Polymer solutions

    Science.gov (United States)

    Krawczyk, Gerhard Erich [Bremen, DE; Miller, Kevin Michael [West Dundee, IL

    2011-07-26

    There is provided a method of making a polymer solution comprising polymerizing one or more monomer in a solvent, wherein said monomer comprises one or more ethylenically unsaturated monomer that is a multi-functional Michael donor, and wherein said solvent comprises 40% or more by weight, based on the weight of said solvent, one or more multi-functional Michael donor.

  1. Solution Prototype

    DEFF Research Database (Denmark)

    Efeoglu, Arkin; Møller, Charles; Serie, Michel

    2013-01-01

    environment. The solution prototype that is composed from blending product and service prototype has particular impacts on the dualism of DSR’s “Build” and “Evaluate”. Since the mix between product and service prototyping can be varied, there is a demand for a more agile and iterative framework. Van de Ven...

  2. Podcast solutions

    CERN Document Server

    Geoghegan, Michael W

    2005-01-01

    Podcasting is the art of recording radio show style audio tracks, then distributing them to listeners on the Web via podcasting software such as iPodder. From downloading podcasts to producing a track for fun or profit, ""Podcast Solutions"" covers the entire world of podcasting with insight, humor, and the unmatched wisdom of experience.

  3. Stability and periodic solutions of ordinary and functional differential equations

    CERN Document Server

    Burton, T A

    1985-01-01

    In this book, we study theoretical and practical aspects of computing methods for mathematical modelling of nonlinear systems. A number of computing techniques are considered, such as methods of operator approximation with any given accuracy; operator interpolation techniques including a non-Lagrange interpolation; methods of system representation subject to constraints associated with concepts of causality, memory and stationarity; methods of system representation with an accuracy that is the best within a given class of models; methods of covariance matrix estimation;methods for low-rank mat

  4. Solitary wave and periodic wave solutions for Burgers, Fisher ...

    Indian Academy of Sciences (India)

    2015-11-27

    Proceedings of the International Workshop/Conference on Computational Condensed Matter Physics and Materials Science (IWCCMP-2015). Posted on November 27, 2015. Guest Editors: Anurag Srivastava, C. S. Praveen, H. S. Tewari. © 2015 Indian Academy of Sciences, Bengaluru. Contact | Site index.

  5. Solitons and periodic solutions to a couple of fractional nonlinear ...

    Indian Academy of Sciences (India)

    in engineering science and theoretical physics with fractional evolution. They are foam drainage equation and Klein–Gordon equation, the latter of which is considered in (2+1) dimensions. Foam drainage is the flow of liquid through foam when the effects of capillarity and gravity are taken into consideration. The physics of ...

  6. Solitons and periodic solutions to a couple of fractional nonlinear ...

    Indian Academy of Sciences (India)

    2014-02-26

    Feb 26, 2014 ... Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 3 ... First integral method; solitons; foam drainage equation; Klein–Gordon equation. ... East of Guilan, University of Guilan, Rudsar, Iran; Department of Mathematics, Faculty of Mathematical Sciences, University of Mazandaran, Babolsar, Iran ...

  7. Solitons and periodic solutions to a couple of fractional nonlinear ...

    Indian Academy of Sciences (India)

    2014-02-26

    Feb 26, 2014 ... This paper studies a couple of fractional nonlinear evolution equations using first integral method. These evolution equations are foam drainage equation and Klein–Gordon equation (KGE), the latter of which is considered in (2 + 1) dimensions. For the fractional evolution, the Jumarie's modified ...

  8. Periodic Solutions of Hamiltonian Systems of 3-Body Type

    Science.gov (United States)

    1989-08-01

    As has been noted earlier. a(C) < 4(4 + C2) - 1 implies this is impossible. Thus I has no critical points in this region and there does not exist a...unstable manifolds for Z 12 in the region e1 <- J 1 2(q) -< M + 1 have a transversal intersection. Points on the unstable manifold between levels ci...Hamiltonian systems, Nonlinear Analysis: TMA, 12, (1988), 259-270. [7] Marino, A. and G. Prodi, Metodi perturbativi nella teoria di Morse, Boll. Un. Mat

  9. Periodic solutions and bifurcations of delay-differential equations

    International Nuclear Information System (INIS)

    He Jihuan

    2005-01-01

    In this Letter a simple but effective iteration method is proposed to search for limit cycles or bifurcation curves of delay-differential equations. An example is given to illustrate its convenience and effectiveness

  10. Periodic and subharmonic solutions for second order p-Laplacian ...

    Indian Academy of Sciences (India)

    ... Packaging Engineering Institute, Jinan University, Zhuhai 519070, People's Republic of China; College of Mathematics and Information Sciences, Guangzhou University, Guangzhou 510006, People's Republic of China; Basic Courses Department, Guangdong Construction Vocational Technology Institute, Guangzhou ...

  11. Solitons and periodic solutions to a couple of fractional nonlinear ...

    Indian Academy of Sciences (India)

    KGE), on the other hand, is a relativistic field equation for scalar particles (spin-0). KGE is a relativistic generalization of the well-known. Schrödinger's equation. While there are other relativistic wave equations, KGE has been the most frequently ...

  12. A Newton--Galerkin Method for Fluid Flow Exhibiting Uncertain Periodic Dynamics

    KAUST Repository

    Schick, M.

    2014-01-01

    The determination of stable limit-cycles plays an important role in quantifying the characteristics of dynamical systems. In practice, exact knowledge of model parameters is rarely available leading to parameter uncertainties, which can be modeled as an input of random variables. This has the effect that the limit-cycles become stochastic themselves, resulting in almost surely time-periodic solutions with a stochastic period. In this paper we introduce a novel numerical method for the computation of stable stochastic limit-cycles based on the spectral stochastic finite element method using polynomial chaos (PC). We are able to overcome the difficulties of PC regarding its well-known convergence breakdown for long term integration. To this end, we introduce a stochastic time scaling which treats the stochastic period as an additional random variable and controls the phase-drift of the stochastic trajectories, keeping the necessary PC order low. Based on the rescaled governing equations, we aim at determining an initial condition and a period such that the trajectories close after completion of one stochastic cycle. Furthermore, we verify the numerical method by computation of a vortex shedding of a flow around a circular domain with stochastic inflow boundary conditions as a benchmark problem. The results are verified by comparison to purely deterministic reference problems and demonstrate high accuracy up to machine precision in capturing the stochastic variations of the limit-cycle.

  13. Stability studies of lincomycin hydrochloride in aqueous solution and intravenous infusion fluids.

    Science.gov (United States)

    Czarniak, Petra; Boddy, Michael; Sunderland, Bruce; Hughes, Jeff D

    2016-01-01

    The purpose of this study was to evaluate the chemical stability of Lincocin(®) (lincomycin hydrochloride) in commonly used intravenous fluids at room temperature (25°C), at accelerated-degradation temperatures and in selected buffer solutions. The stability of Lincocin(®) injection (containing lincomycin 600 mg/2 mL as the hydrochloride) stored at 25°C±0.1°C in sodium lactate (Hartmann's), 0.9% sodium chloride, 5% glucose, and 10% glucose solutions was investigated over 31 days. Forced degradation of Lincocin(®) in hydrochloric acid, sodium hydroxide, and hydrogen peroxide was performed at 60°C. The effect of pH on the degradation rate of lincomycin hydrochloride stored at 80°C was determined. Lincomycin hydrochloride w as found to maintain its shelf life at 25°C in sodium lactate (Hartmann's) solution, 0.9% sodium chloride solution, 5% glucose solution, and 10% glucose solution, with less than 5% lincomycin degradation occurring in all intravenous solutions over a 31-day period. Lincomycin hydrochloride showed less rapid degradation at 60°C in acid than in basic solution, but degraded rapidly in hydrogen peroxide. At all pH values tested, lincomycin followed first-order kinetics. It had the greatest stability near pH 4 when stored at 80°C (calculated shelf life of 4.59 days), and was least stable at pH 2 (calculated shelf life of 0.38 days). Lincocin(®) injection was chemically found to have a shelf life of at least 31 days at 25°C when added to sodium lactate (Hartmann's) solution, 0.9% sodium chloride solution, 5% glucose solution, and 10% glucose solution. Solutions prepared at approximately pH 4 are likely to have optimum stability.

  14. Long-Term Stability of Tramadol and Ketamine Solutions for Patient-Controlled Analgesia Delivery.

    Science.gov (United States)

    Gu, Junfeng; Qin, Wengang; Chen, Fuchao; Xia, Zhongyuan

    2015-08-26

    Subanesthetic doses of ketamine as an adjuvant to tramadol in patient-controlled analgesia (PCA) for postoperative pain have been shown to improve the quality of analgesia. However, there are no such commercially available drug mixtures, and the stability of the combination has rarely been assessed. Admixtures were assessed for periods of up to 14 days at 4°C and 25°C. Three different mixtures of tramadol and ketamine (tramadol 5.0 mg/mL + ketamine 0.5 mg/mL, tramadol 5.0 mg/mL + ketamine 1.0 mg/mL, and tramadol 5.0 mg/mL + ketamine 2.0 mg/mL) were prepared in polyolefin bags by combining these 2 drugs with 0.9% sodium chloride (normal saline [NS]). The chemical stability of the admixtures was evaluated by a validated high-performance liquid chromatography (HPLC) method and by measurement of pH values. Solution appearance and color were assessed by observing the samples against black and white backgrounds. Solutions were considered stable if they maintained 90% of the initial concentration of each drug. The percentages of initial concentration of tramadol and ketamine in the various solutions remained above 98% when stored at 4°C or 25°C over the testing period. No changes in color or turbidity were observed in any of the prepared solutions. Throughout this period, pH values remained stable. The results indicate that the drug mixtures of tramadol with ketamine in NS for PCA delivery systems were stable for 14 days when stored in polyolefin bags at 4°C or 25°C.

  15. Stability analysis of new exact traveling-wave solutions of new coupled KdV and new coupled Zakharov-Kuznetsov systems

    Science.gov (United States)

    Seadawy, Aly R.; Arshad, M.; Lu, Dianchen

    2017-04-01

    In this article, our aim is to further extend the applications of modified extended direct algebraic method on new coupled systems, which have many important applications in mathematical physics. many exact solutions out of which some are new in different forms such as soliton, solitary wave, periodic, elliptic function solutions of new coupled KdV and new coupled Zakharov-Kuznetsov (ZK) systems are constructed by employing this method. The constructed exact solutions are also presented graphically. The modulation instability is utilized to discuss the stability of obtained solutions. All solutions are stable and exact solutions. The obtained results show that the modified extended method is general and effective. Furthermore, many other new coupled systems arising in mathematical physics can also be solved by this powerful and effective method.

  16. Toward Practical Secure Stable Matching

    Directory of Open Access Journals (Sweden)

    Riazi M. Sadegh

    2017-01-01

    Full Text Available The Stable Matching (SM algorithm has been deployed in many real-world scenarios including the National Residency Matching Program (NRMP and financial applications such as matching of suppliers and consumers in capital markets. Since these applications typically involve highly sensitive information such as the underlying preference lists, their current implementations rely on trusted third parties. This paper introduces the first provably secure and scalable implementation of SM based on Yao’s garbled circuit protocol and Oblivious RAM (ORAM. Our scheme can securely compute a stable match for 8k pairs four orders of magnitude faster than the previously best known method. We achieve this by introducing a compact and efficient sub-linear size circuit. We even further decrease the computation cost by three orders of magnitude by proposing a novel technique to avoid unnecessary iterations in the SM algorithm. We evaluate our implementation for several problem sizes and plan to publish it as open-source.

  17. Periodic perturbations of quadratic planar polynomial vector fields

    Directory of Open Access Journals (Sweden)

    MARCELO MESSIAS

    2002-06-01

    Full Text Available In this work are studied periodic perturbations, depending on two parameters, of quadratic planar polynomial vector fields having an infinite heteroclinic cycle, which is an unbounded solution joining two saddle points at infinity. The global study envolving infinity is performed via the Poincaré compactification. The main result obtained states that for certain types of periodic perturbations, the perturbed system has quadratic heteroclinic tangencies and transverse intersections between the local stable and unstable manifolds of the hyperbolic periodic orbits at infinity. It implies, via the Birkhoff-Smale Theorem, in a complex dynamical behavior of the solutions of the perturbed system, in a finite part of the phase plane.Neste trabalho são estudadas perturbações periódicas, dependendo de dois parâmetros, de campos vetoriais polinomiais planares que possuem um ciclo heteroclínico infinito, que consiste de uma solução ilimitada, que conecta dois pontos de sela no infinito. O estudo global do campo vetorial, envolvendo o infinito, foi elaborado utilizando-se a compactificação de Poincaré. O resultado principal estabelece que, para certo tipo de perturbação periódica, o sistema apresenta tangências heteroclínicas e intersecção transversal das variedades invariantes de órbitas periódicas no infinito, o que implica, via o Teorema de Birkhoff-Smale, em um comportamento dinâmico bastante complexo das soluções do sistema perturbado, em uma região finita do plano de fase.

  18. Application of stable isotope to breath test

    International Nuclear Information System (INIS)

    Sasaki, Yasuto

    1988-01-01

    Needles to say, radioisotopes have good characteristics as a tracer for examining biological functions. In fact, scyntigraphy is widely used over Japan. It is true, however, that there are some difficulties in applying radioisotopes to humans. Thus, greater attention began to be attracted to stable isotopes in the late 1960s, because these substances can be used for infants and pregnant women. They can be stored for a long period of time since they do not suffer damping as in the case of radioisotopes. In addition to serving as a tracer, stable isotopes can provide structural-chemical information including the position of isotope labels, and the mass and atomic composition of fragment ions. Such techniques as NMR spectroscopy is employed for this purpose. The method is currently used to perform examinations of congenital metabolic disorders. The carbon isotopes of 13 C and 14 C are used for breath test. Compounds labeled with these isotopes are administered and their ratio to the total CO 2 in breath is measured to diagnose diseases. In the early 1970s, 13 C has come into use for breath test. Similar breath test is applied to diagnosis of the bacterial overgrowth syndrome and ileal dysfunction syndrome. (Nogami, K.)

  19. Stable states in a strong IR field

    Science.gov (United States)

    Zhong, Changchun; Robicheaux, Francis

    2015-05-01

    It is found that 10% of atoms stay in the quasi-stable states after being exposed to intense laser or microwave (MW) pulses, even though the pulses' intensity is much stronger than that needed for static fields ionization. The reason why atoms survive those strong pulses has attracted growing attentions. A. Arakelyan et al. have observed the optical spectra of the surviving Lithium atoms after interaction with intense 38-GHz MW fields for more than 1000 cycles, and the spectra exhibit a periodic train of peaks 38 GHz apart. It suggests that those weakly bound Rydberg electrons seldom go back to the ionic core, where the cycle average energy exchange happens. In this study, we are interested in the electron behavior in the presence of intense infrared fields with a much shorter wavelength (1000 nm). By solving the full 3D time dependent Schrodinger equation, we calculate the spectra of the surviving atoms under intense IR fields. Our numerical calculations show atoms survive the intense field in quasi-stable states for a long time, and the optical spectra are obviously modulated by the IR frequency. Through tuning the ponderomotive energy, we see how field parameters affect the behavior of electrons. Different atoms, such as Hydrogen, Helium, Lithium, and Sodium, are tested to see how atom's energy structures influence the results.

  20. Towards stable acceleration in LINACS

    CERN Document Server

    Dubrovskiy, A D

    2014-01-01

    Ultra-stable and -reproducible high-energy particle beams with short bunches are needed in novel linear accelerators and, in particular, in the Compact Linear Collider CLIC. A passive beam phase stabilization system based on a bunch compression with a negative transfer matrix element R56 and acceleration at a positive off-crest phase is proposed. The motivation and expected advantages of the proposed scheme are outlined.

  1. Stable Oxygen-18 and Deuterium Isotopes

    DEFF Research Database (Denmark)

    Müller, Sascha

    The application of stable Oxygen-18 (18O) and Deuterium (2H) isotopes, as a tracer for fluxes between different compartments of the water cycle was subject of the present PhD-thesis. During a three year period, temporal data from a wide range of water cycle constituents was collected from...... the Skjern River catchment, Denmark. The presented applications focused on studying the isotopic 'input signal' to the hydrosphere in the form of precipitation, the isotopic 'output signal' with its related dynamic processes at a coastal saltwater-freshwater interface (groundwater isotopes) and the temporal...... development within a given lowland headwater catchment (stream water isotopes). Based on our investigations on the precipitation isotopic composition a local meteoric water line (LMWL) was constructed and expressed as: δ2H=7.4 δ18O + 5.36‰. Moreover, we showed that under maritime temperature climate influence...

  2. Self-similar anomalous diffusion and Levy-stable laws

    International Nuclear Information System (INIS)

    Uchaikin, Vladimir V

    2003-01-01

    Stochastic principles for constructing the process of anomalous diffusion are considered, and corresponding models of random processes are reviewed. The self-similarity and the independent-increments principles are used to extend the notion of diffusion process to the class of Levy-stable processes. Replacing the independent-increments principle with the renewal principle allows us to take the next step in generalizing the notion of diffusion, which results in fractional-order partial space-time differential equations of diffusion. Fundamental solutions to these equations are represented in terms of stable laws, and their relationship to the fractality and memory of the medium is discussed. A new class of distributions, called fractional stable distributions, is introduced. (reviews of topical problems)

  3. High precision and stable structures for particle detectors

    CERN Document Server

    Da Mota Silva, S; Hauviller, Claude

    1999-01-01

    The central detectors used in High Energy Physics Experiments require the use of light and stable structures capable of supporting delicate and precise radiation detection elements. These structures need to be highly stable under environmental conditions where external vibrations, high radiation levels, temperature and humidity gradients should be taken into account. Their main design drivers are high dimension and dynamic stability, high stiffness to mass ratio and large radiation length. For most applications, these constraints lead us to choose Carbon Fiber Reinforced Plastics ( CFRP) as structural element. The construction of light and stable structures with CFRP for these applications can be achieved by careful design engineering and further confirmation at the prototyping phase. However, the experimental environment can influence their characteristics and behavior. In this case, theuse of adaptive structures could become a solution for this problem. We are studying structures in CFRP with bonded piezoel...

  4. Stability of aflatoxins in solution.

    Science.gov (United States)

    Diaz, Gonzalo J; Cepeda, Sandra M; Martos, Perry A

    2012-01-01

    The stability of aflatoxins B1, B2, G1, and G2 was studied in solutions containing different concentrations of water, acetonitrile, and/or methanol, and in autosampler vials treated with nitric acid or silanized. When stored at room temperature (20 degrees C) for 24 h, aflatoxins G1 and G2 were stable only in solutions containing 100% organic solvent, whereas aflatoxins B1 and B2 were stable in solutions of methanol-water and acetonitrile-water at greater than 60 and 40% organic content, respectively. At 5 degrees C, aflatoxins G1 and G2 showed a significant decrease in concentration only when kept in less than 20% aqueous organic solvent. Significant loss of aflatoxins was realized in standard, commercially available amber type I borosilicate autosampler vials, but chemical etching of the vials with nitric acid or with silanization prevented aflatoxin degradation. These results indicate that aflatoxins are unstable in aqueous solutions and that this instability can be counteracted by the presence of at least 20% organic solvent and keeping the solutions at 5 degrees C or by the use of treated vials.

  5. Exponential stability of linear and almost periodic systems on Banach spaces

    Directory of Open Access Journals (Sweden)

    Constantin Buse

    2003-12-01

    Full Text Available Let $v_f(cdot, 0$ the mild solution of the well-posed inhomogeneous Cauchy problem $$ dot v(t=A(tv(t+f(t, quad v(0=0quad tge 0 $$ on a complex Banach space $X$, where $A(cdot$ is an almost periodic (possible unbounded operator-valued function. We prove that $v_f(cdot, 0$ belongs to a suitable subspace of bounded and uniformly continuous functions if and only if for each $xin X$ the solution of the homogeneous Cauchy problem $$ dot u(t=A(tu(t, quad u(0=xquad tge 0 $$ is uniformly exponentially stable. Our approach is based on the spectral theory of evolution semigroups.

  6. A simple route to prepare stable hydroxyapatite nanoparticles suspension

    Science.gov (United States)

    Han, Yingchao; Wang, Xinyu; Li, Shipu

    2009-07-01

    A simple ultrasound assisted precipitation method with addition of glycosaminoglycans (GAGs) is proposed to prepare stable hydroxyapatite (HAP) nanoparticles suspension from the mixture of Ca(H2PO4)2 solution and Ca(OH)2 solution. The product was characterized by XRD, FT-IR, TEM, HRTEM and particle size, and zeta potential analyzer. TEM observation shows that the suspension is composed of 10-20 nm × 20-50 nm short rod-like and 10-30 nm similar spherical HAP nanoparticles. The number-averaged particle size of stable suspension is about 30 nm between 11.6 and 110.5 nm and the zeta potential is -60.9 mV. The increase of stability of HAP nanoparticles suspension mainly depends on the electrostatic effect and steric effect of GAGs. The HAP nanoparticles can be easily transported into the cancer cells and exhibit good potential as gene or drug carrier system.

  7. Iron metabolism study in humans by means of stable tracers

    International Nuclear Information System (INIS)

    Cantone, M.C.; Molho, N.; Pirola, L.; Gambarini, G.; Hansen, C.; Roth, P.; Werner, E.

    1988-01-01

    An investigation of iron metabolism in a female patient volunteer by administration of stable iron isotopes as tracers was performed. The applied methodology had already been tested in rabbits in comparison with radioactive tracer technique. The subject under study was given 58 Fe solution intravenously and about 45 min later 57 Fe solution orally. Ten blood samples were drawn at different times within 522 min from injection. Single iron isotopes content in plasma samples was determined by proton nuclear activation. A Compton suppressor system was utilized to improve the detector limits. The characteristic parameters of iron plasma clearance and of iron intestinal absorption were determined

  8. Electropolishing of Stainless Steel Implants for Stable Functional Osteosynthesis

    Directory of Open Access Journals (Sweden)

    Omel’chuk, A.О.

    2016-01-01

    Full Text Available A new method for the electropolishing stainless steel for stable functional osteosynthesis has been developed. The polishing of implants was carried out in solutions, based on the ternary system H2SO4—H3PO4—H2O with stepwise decreasing the current density and increasing the orthophosphoric acid concentration. The optimal polishing conditions (current density, solution composition, temperature and duration have been determined. The developed method improves the quality and mechanical properties of the surface.

  9. Metal stable isotope signatures as tracers in environmental geochemistry.

    Science.gov (United States)

    Wiederhold, Jan G

    2015-03-03

    The biogeochemical cycling of metals in natural systems is often accompanied by stable isotope fractionation which can now be measured due to recent analytical advances. In consequence, a new research field has emerged over the last two decades, complementing the traditional stable isotope systems (H, C, O, N, S) with many more elements across the periodic table (Li, B, Mg, Si, Cl, Ca, Ti, V, Cr, Fe, Ni, Cu, Zn, Ge, Se, Br, Sr, Mo, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, U) which are being explored and potentially applicable as novel geochemical tracers. This review presents the application of metal stable isotopes as source and process tracers in environmental studies, in particular by using mixing and Rayleigh model approaches. The most important concepts of mass-dependent and mass-independent metal stable isotope fractionation are introduced, and the extent of natural isotopic variations for different elements is compared. A particular focus lies on a discussion of processes (redox transformations, complexation, sorption, precipitation, dissolution, evaporation, diffusion, biological cycling) which are able to induce metal stable isotope fractionation in environmental systems. Additionally, the usefulness and limitations of metal stable isotope signatures as tracers in environmental geochemistry are discussed and future perspectives presented.

  10. Searching for stable orbits in the HD 10180 planetary system

    Directory of Open Access Journals (Sweden)

    Laskar J.

    2011-02-01

    Full Text Available A planetary system with at least seven planets has been found around the star HD 10180. However, the traditional Keplerian and n-body fits to the data provide an orbital solution that becomes unstable very quickly, which may quest the reliability of the observations. Here we show that stable orbital configurations can be obtained if general relativity and long-term dissipation raised by tides on the innermost planet are taken into account.

  11. Dynamical behaviours and exact travelling wave solutions of ...

    Indian Academy of Sciences (India)

    Modified generalized Vakhnenko equation; cusped solitons; loop solitons; periodic cusp wave solutions; smooth periodic wave solutions; pseudopeakon solitons; ... Guangxi 541004, People's Republic of China; School of Mathematics and Statistics, Guizhou University of Finance and Economics, Guiyang, Guizhou 550025, ...

  12. Thyrotoxic periodic paralysis

    Science.gov (United States)

    ... have a family history of periodic paralysis or thyroid disorders. Emergency symptoms include: Difficulty breathing, speaking, or swallowing ... Prevention Genetic counseling may be advised. Treating the thyroid disorder prevents attacks of weakness. Alternative Names Periodic paralysis - ...

  13. Your First Period

    Science.gov (United States)

    ... on your abdomen or lower back. What is amenorrhea? Amenorrhea means not having a period. It is normal ... or less often than every 45 days. Glossary Amenorrhea: The absence of menstrual periods. Egg: The female ...

  14. Stable Hemiaminals: 2-Aminopyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Anna Kwiecień

    2015-08-01

    Full Text Available Stable hemiaminals can be obtained in the one-pot reaction between 2-aminopyrimidine and nitrobenzaldehyde derivatives. Ten new hemiaminals have been obtained, six of them in crystal state. The molecular stability of these intermediates results from the presence of both electron-withdrawing nitro groups as substituents on the phenyl ring and pyrimidine ring, so no further stabilisation by intramolecular interaction is required. Hemiaminal molecules possess a tetrahedral carbon atom constituting a stereogenic centre. As the result of crystallisation in centrosymmetric space groups both enantiomers are present in the crystal structure.

  15. Organic synthesis with stable isotopes

    International Nuclear Information System (INIS)

    Daub, G.H.; Kerr, V.N.; Williams, D.L.; Whaley, T.W.

    1978-01-01

    Some general considerations concerning organic synthesis with stable isotopes are presented. Illustrative examples are described and discussed. The examples include DL-2-amino-3-methyl- 13 C-butanoic-3,4- 13 C 2 acid (DL-valine- 13 C 3 ); methyl oleate-1- 13 C; thymine-2,6- 13 C 2 ; 2-aminoethanesulfonic- 13 C acid (taurine- 13 C); D-glucose-6- 13 C; DL-2-amino-3-methylpentanoic-3,4- 13 C 2 acid (DL-isoleucine- 13 C 2 ); benzidine- 15 N 2 ; and 4-ethylsulfonyl-1-naphthalene-sulfonamide- 15 N

  16. Book Reviews in Periodicals.

    Science.gov (United States)

    Ettelt, Harold J.

    All recent issues of periodicals found which contain indexed book reviews are listed in this compilation from Drake Memorial Library at the New York State University at Brockport. The periodicals are listed by 29 subject headings in this informal guide designed to be used at Drake Library. The number of reviews in the periodical in a recent year…

  17. The Periodic Pyramid

    Science.gov (United States)

    Hennigan, Jennifer N.; Grubbs, W. Tandy

    2013-01-01

    The chemical elements present in the modern periodic table are arranged in terms of atomic numbers and chemical periodicity. Periodicity arises from quantum mechanical limitations on how many electrons can occupy various shells and subshells of an atom. The shell model of the atom predicts that a maximum of 2, 8, 18, and 32 electrons can occupy…

  18. Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Nikhil, E-mail: nkumar.phd2011.bt@nitrr.ac.in; Upadhyay, Lata Sheo Bachan, E-mail: contactlataupadhyay@gmail.com

    2016-11-01

    Highlights: • A facile and eco-friendly method for the synthesis of L-cysteine functionalized copper nanoparticles is reported. • Synthesis of Highly stable L-cysteine functionalized copper nanoparticles (∼40 nm) was done in an aqueous medium. • FTIR analysis shows that L-cysteine bound to the nanoparticle surface via thiol group. - Abstract: A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month.

  19. Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

    International Nuclear Information System (INIS)

    Kumar, Nikhil; Upadhyay, Lata Sheo Bachan

    2016-01-01

    Highlights: • A facile and eco-friendly method for the synthesis of L-cysteine functionalized copper nanoparticles is reported. • Synthesis of Highly stable L-cysteine functionalized copper nanoparticles (∼40 nm) was done in an aqueous medium. • FTIR analysis shows that L-cysteine bound to the nanoparticle surface via thiol group. - Abstract: A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month

  20. A Stable, Extreme Temperature, High Radiation, Compact. Low Power Clock Oscillator for Space, Geothermal, Down-Hole & other High Reliability Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Efficient and stable clock signal generation requirements at extreme temperatures and high radiation are not met with the current solutions. Chronos Technology...

  1. Stable cosmology in chameleon bigravity

    Science.gov (United States)

    De Felice, Antonio; Mukohyama, Shinji; Oliosi, Michele; Watanabe, Yota

    2018-02-01

    The recently proposed chameleonic extension of bigravity theory, by including a scalar field dependence in the graviton potential, avoids several fine-tunings found to be necessary in usual massive bigravity. In particular it ensures that the Higuchi bound is satisfied at all scales, that no Vainshtein mechanism is needed to satisfy Solar System experiments, and that the strong coupling scale is always above the scale of cosmological interest all the way up to the early Universe. This paper extends the previous work by presenting a stable example of cosmology in the chameleon bigravity model. We find a set of initial conditions and parameters such that the derived stability conditions on general flat Friedmann background are satisfied at all times. The evolution goes through radiation-dominated, matter-dominated, and de Sitter eras. We argue that the parameter space allowing for such a stable evolution may be large enough to encompass an observationally viable evolution. We also argue that our model satisfies all known constraints due to gravitational wave observations so far and thus can be considered as a unique testing ground of gravitational wave phenomenologies in bimetric theories of gravity.

  2. Abundant stable gauge field hair for black holes in anti-de Sitter space.

    Science.gov (United States)

    Baxter, J E; Helbling, Marc; Winstanley, Elizabeth

    2008-01-11

    We present new hairy black hole solutions of SU(N) Einstein-Yang-Mills (EYM) theory in asymptotically anti-de Sitter (AdS) space. These black holes are described by N+1 independent parameters and have N-1 independent gauge field degrees of freedom. Solutions in which all gauge field functions have no zeros exist for all N, and for a sufficiently large (and negative) cosmological constant. At least some of these solutions are shown to be stable under classical, linear, spherically symmetric perturbations. Therefore there is no upper bound on the amount of stable gauge field hair with which a black hole in AdS can be endowed.

  3. Compatibility considerations in parenteral nutrient solutions.

    Science.gov (United States)

    Niemiec, P W; Vanderveen, T W

    1984-05-01

    Information on compatibility of nutrients and drugs with parenteral nutrient (PN) solutions is reviewed and evaluated. Precipitation of calcium phosphate when calcium and phosphate salts are added can be affected by pH, amino acid concentration, amino acid product, temperature, sequence of additives, specific salt used, and time since admixture; precipitate formation can occur gradually over 24 hours. Insulin is chemically stable in PN solutions, but adsorption to the infusion system can cause decreased availability. Poor delivery of vitamin A via PN solutions has been reported. The sodium bisulfite content of amino acid injections may cause degradation of thiamine, but studies simulating clinical use are needed. Folic acid stability in PN solutions has been demonstrated, and phytonadione appears to be stable. Drug administration via PN solutions may be advantageous when fluid intake is restricted or peripheral vein access is limited and in home PN therapy. Summarized are results of studies involving heparin, cimetidine hydrochloride, aminophylline, amphotericin B, iron dextran, hydrochloric acid, corticosteroids, narcotics, metoclopramide, digoxin, and fluorouracil. Many antibiotics are probably stable, especially when administered by co-infusion rather than by direct mixture in the PN solution container. When lipids are mixed in the same container with amino acid-dextrose solutions, compatibility and stability of electrolytes, vitamins, and trace elements must be reassessed. Practical research is needed, and availability of additives should be studied in specific patient populations and for specific PN formulations. Valid conclusions are dependent on careful study design.

  4. Solution Leaching

    Science.gov (United States)

    Chun, Tiejun; Zhu, Deqing; Pan, Jian; He, Zhen

    2014-06-01

    Recovery of alumina from magnetic separation tailings of red mud has been investigated by Na2CO3 solution leaching. X-ray diffraction (XRD) results show that most of the alumina is present as 12CaO·7Al2O3 and CaO·Al2O3 in the magnetic separation tailings. The shrinking core model was employed to describe the leaching kinetics. The results show that the calculated activation energy of 8.31 kJ/mol is characteristic for an internal diffusion-controlled process. The kinetic equation can be used to describe the leaching process. The effects of Na2CO3 concentration, liquid-to-solid ratio, and particle size on recovery of Al2O3 were examined.

  5. The intrinsic periodic fluctuation of forest: a theoretical model based on diffusion equation

    Science.gov (United States)

    Zhou, J.; Lin, G., Sr.

    2015-12-01

    Most forest dynamic models predict the stable state of size structure as well as the total basal area and biomass in mature forest, the variation of forest stands are mainly driven by environmental factors after the equilibrium has been reached. However, although the predicted power-law size-frequency distribution does exist in analysis of many forest inventory data sets, the estimated distribution exponents are always shifting between -2 and -4, and has a positive correlation with the mean value of DBH. This regular pattern can not be explained by the effects of stochastic disturbances on forest stands. Here, we adopted the partial differential equation (PDE) approach to deduce the systematic behavior of an ideal forest, by solving the diffusion equation under the restricted condition of invariable resource occupation, a periodic solution was gotten to meet the variable performance of forest size structure while the former models with stable performance were just a special case of the periodic solution when the fluctuation frequency equals zero. In our results, the number of individuals in each size class was the function of individual growth rate(G), mortality(M), size(D) and time(T), by borrowing the conclusion of allometric theory on these parameters, the results perfectly reflected the observed "exponent-mean DBH" relationship and also gave a logically complete description to the time varying form of forest size-frequency distribution. Our model implies that the total biomass of a forest can never reach a stable equilibrium state even in the absence of disturbances and climate regime shift, we propose the idea of intrinsic fluctuation property of forest and hope to provide a new perspective on forest dynamics and carbon cycle research.

  6. Do planetary seasons play a role in attaining stable climates?

    Science.gov (United States)

    Olsen, Kasper Wibeck; Bohr, Jakob

    2018-02-01

    A simple phenomenological account for planetary climate instabilities is presented. The description is based on the standard model where the balance of incoming stellar radiation and outward thermal radiation is described by the effective planet temperature. Often, it is found to have three different points, or temperatures, where the influx of radiation is balanced with the out-flux, even with conserved boundary conditions. Two of these points are relatively long-term stable, namely the point corresponding to a cold climate and the point corresponding to a hot climate. In a classical sense these points are equilibrium balance points. The hypothesis promoted in this paper is the possibility that the intermediate third point can become long-term stable by being driven dynamically. The initially unstable point is made relatively stable over a long period by the presence of seasonal climate variations.

  7. Stable isotope mass spectrometry in petroleum exploration

    International Nuclear Information System (INIS)

    Mathur, Manju

    1997-01-01

    The stable isotope mass spectrometry plays an important role to evaluate the stable isotopic composition of hydrocarbons. The isotopic ratios of certain elements in petroleum samples reflect certain characteristics which are useful for petroleum exploration

  8. Siemens IT solutions for power sector

    International Nuclear Information System (INIS)

    Lunter, P.

    2004-01-01

    The cost reduction, flexibility and revenue increase, potential exploitation, productivity increase, and business opportunities exploitation - that is all what can be required in the races for the promonent positioning on the electricity power market. These requirements can be realized by the sophisticated IT solutions hand-tailored to the special requirements of the electric power producers and tradesmen. This approach makes it possible to achieve greater profit. Our solutions 'PROFIT Solutions', that are symbiosis of the most progressive information technologies and the power plant techniques of the company Siemens, satisfy submitted specifications in substantial measure. The system solutions 'PROFIT Solutions' comprise three solution groups: process, operation a business. The solutions of the group 'IT Process Solutions' increase flexibility and manoeuvrability of equipment, improve the efficiency and contribute to more economical operation of the power generation. Solutions 'IT Process Solutions' simplify and shorten the period of power cycles and conduce to higher labour productivity. Solutions group 'IT Process Solutions' approaches equipment to the market - supports the profit strategies, helps quickly and expertly to determine and predict hazards. The extension PROFIT Cockpit means the nuance to the solutions world 'PROFIT Solutions'. The survey about the whole installation is within reach at the simple touch of a button. It is possible to compile the total system part by part from single solutions 'PROFIT Solutions'. As a matter of fact all single parts can be interconnected with already existing solutions. Routines 'PROFIT Solutions' cooperate with all modern control systems. (author)

  9. Stable rotating dipole solitons in nonlocal media

    DEFF Research Database (Denmark)

    Lopez-Aguayo, Servando; Skupin, Stefan; Desyatnikov, Anton S.

    2006-01-01

    We present the first example of stable rotating two-soliton bound states in nonlinear optical media with nonlocal response. We show that, in contrast to media with local response, nonlocality opens possibilities to generate stable azimuthons.......We present the first example of stable rotating two-soliton bound states in nonlinear optical media with nonlocal response. We show that, in contrast to media with local response, nonlocality opens possibilities to generate stable azimuthons....

  10. Computing Diverse Optimal Stable Models

    OpenAIRE

    Romero, Javier; Schaub, Torsten; Wanko, Philipp

    2016-01-01

    We introduce a comprehensive framework for computing diverse (or similar) solutions to logic programs with preferences. Our framework provides a wide spectrum of complete and incomplete methods for solving this task. Apart from proposing several new methods, it also accommodates existing ones and generalizes them to programs with preferences. Interestingly, this is accomplished by integrating and automating several basic ASP techniques - being of general interest even beyond diversification. ...

  11. Uses of stable isotopes in fish ecology

    Science.gov (United States)

    Analyses of fish tissues (other than otoliths) for stable isotope ratios can provide substantial information on fish ecology, including physiological ecology. Stable isotopes of nitrogen and carbon frequently are used to determine the mix of diet sources for consumers. Stable i...

  12. Differently Environment Stable Bio-Silver Nanoparticles: Study on Their Optical Enhancing and Antibacterial Properties

    Science.gov (United States)

    Balachandran, Yekkuni L.; Girija, Shanmugam; Selvakumar, Rajendran; Tongpim, Saowanit; Gutleb, Arno C.; Suriyanarayanan, Sarvajeyakesavalu

    2013-01-01

    Generally, limited research is extended in studying stability and applicational properties of silver nanoparticles (Ag NPs) synthesized by adopting ‘green chemistry’ protocol. In this work, we report on the synthesis of stable Ag NPs using plant-derived materials such as leaf extract of Neem (Azadirachta indica) and biopolymer pectin from apple peel. In addition, the applicational properties of Ag NPs such as surface-enhanced Raman scattering (SERS) and antibacterial efficiencies were also investigated. As-synthesized nanoparticles (NPs) were characterized using various instrumentation techniques. Both the plant materials (leaf extract and biopolymer) favored the synthesis of well-defined NPs capped with biomaterials. The NPs were spherical in shape with an average particle size between 14-27 nm. These bio-NPs exhibited colloidal stability in most of the suspended solutions such as water, electrolyte solutions (NaCl; NaNO3), biological solution (bovine serum albumin), and in different pH solutions (pH 7; 9) for a reasonable time period of 120 hrs. Both the bio-NPs were observed to be SERS active through displaying intrinsic SERS signals of the Raman probe molecule (Nile blue A). The NPs were effective against the Escherichia coli bacterium when tested in nutrient broth and agar medium. Scanning and high-resolution transmission electron microscopy (SEM and HRTEM) images confirmed cellular membrane damage of nanoparticle treated E. coli cells. These environmental friendly template Ag NPs can be used as an antimicrobial agent and also for SERS based analytical applications. PMID:24130832

  13. Theory of stable allocations II

    Directory of Open Access Journals (Sweden)

    Pantelić Svetlana

    2015-01-01

    Full Text Available The Swedish Royal Academy awarded the 2012 Nobel Prize in Economics to Lloyd Shapley and Alvin Roth, for the theory of stable allocations and the practice of market design. These two American researchers worked independently from each other, combining basic theory and empirical investigations. Through their experiments and practical design they generated a flourishing field of research and improved the performance of many markets. Shapley provided the fundamental theoretical contribution to this field of research, whereas Roth, a professor at the Harvard University in Boston, developed and upgraded these theoretical investigations by applying them to the American market of medical doctors. Namely, their research helps explain the market processes at work, for instance, when doctors are assigned to hospitals, students to schools and human organs for transplant to recipients.

  14. Stable massive particles at colliders

    Energy Technology Data Exchange (ETDEWEB)

    Fairbairn, M.; /Stockholm U.; Kraan, A.C.; /Pennsylvania U.; Milstead, D.A.; /Stockholm U.; Sjostrand, T.; /Lund U.; Skands, P.; /Fermilab; Sloan, T.; /Lancaster U.

    2006-11-01

    We review the theoretical motivations and experimental status of searches for stable massive particles (SMPs) which could be sufficiently long-lived as to be directly detected at collider experiments. The discovery of such particles would address a number of important questions in modern physics including the origin and composition of dark matter in the universe and the unification of the fundamental forces. This review describes the techniques used in SMP-searches at collider experiments and the limits so far obtained on the production of SMPs which possess various colour, electric and magnetic charge quantum numbers. We also describe theoretical scenarios which predict SMPs, the phenomenology needed to model their production at colliders and interactions with matter. In addition, the interplay between collider searches and open questions in cosmology such as dark matter composition are addressed.

  15. Middle Helladic Period

    DEFF Research Database (Denmark)

    Sarri, Kalliopi

    1999-01-01

    administration, e.g. the administrative buildings and the sealing of products, were abandoned. The economic decline of the Middle Bronze Age affected the social stratification as well. The changes in social stratification appear in a series of completely new burial customs which show the prevalence of social......The Middle Bronze Age on Mainland Greece is also known as the Middle Helladic period. The chronological framework of this period extends from the beginnings of the second millenium - roughly 1900 - until 1550 BC, that is until the beginnings of the Mycenaean period. The Middle Helladic period...... is considered as the dark period of the cultural decline. The remains of the material culture reveal a clear retrogression while the information available on the social stratification and economy are so few and problematic in interpretation that this period is considered as the "Middle Age of Greek Prehistory...

  16. [Scientific periodicals: quality criteria].

    Science.gov (United States)

    Ferreira, Maria Cecilia Gonzaga; Krzyzanowski, Rosaly Favero

    2003-05-01

    This paper presents a historical literature review on the evaluation of periodicals and the methodology employed for their evaluation. It emphasizes the attention that should be given to the contents of the periodicals and their format based on technical standards in order to reach a global quality of the publications. This paper includes a summary of the most important aspects of the technical standards for periodicals and scientific articles.

  17. Painful menstrual periods

    Science.gov (United States)

    Menstruation - painful; Dysmenorrhea; Periods - painful; Cramps - menstrual; Menstrual cramps ... related activities for a few days during each menstrual cycle. Painful menstruation is the leading cause of ...

  18. Towards effective and stable probiotics.

    Science.gov (United States)

    Yarullina, D R; Damshkaln, L G; Bruslik, N L; Konovalova, O A; Ilinskaya, O N; Lozinsky, V I

    2015-01-01

    Probiotics are live microorganisms, generally either lactobacilli or bifidobacteria, which when administered in adequate amounts confer a health benefit to the host [1]. Due to the growing evidence of health benefits associated with their use, probiotics are of increasing interest and represent now a significant growth area in the functional foods industry [2]. However, to be effective, orally administered probiotics should survive preparation of dosage forms and passage through acidic environment of the gastrointestinal tract (GIT). Reaching the intestine, these microorganisms should be able to establish themselves, remain viable and perform their beneficial actions. In this context, oral formulations have to protect probiotic bacteria from gastric acidity and delay their release in the small intestine in order to allow their complete release in the colon. To evaluate effects of starch formulations of lactobacilli on their survival in gastric environment and probiotic properties. Nineteen Lactobacillus strains belonging to the species L. fermentum (14 strains), L. plantarum (4 strains), and L. rhamnosus (1 strain), were isolated from dairy products and probiotics, and were used in this study. Lactobacilli were cultured in de Man, Rogosa, Sharpe (MRS) broth (Merck, Germany) under microaerobic conditions at 37°C.Amylolytic activity of lactobacilli, cultured for 3-5 days on MRS agar supplemented with 1% soluble potato starch (SPS), was determined with iodine reagent (0.01 M I2-KI solution).Loading in starch was performed with L. plantarum 8PA3 bacteria ("Dry lactobacterin", Perm, Russia), which were resuspended to the concentration 1010 cells/mL in 10 mL of 0.85% NaCl solution and added to 90 mL of 2.5% SPS solution. Resulting mixture was frozen at -18°C and then lyophilized (Martin Christ Alpha 1-2 LDplus, Germany).Atomic force microscopy (AFM) images of formulated L. plantarum 8PA3 cells were acquired in air by a Solver P47H atomic force microscope (NT

  19. Second Period Access Report

    DEFF Research Database (Denmark)

    Maisondieu, Christophe; Giebhardt, Jochen; Tetu, Amelie

    The work described in this publication has received support from the European Community - Research Infrastructure Action under the FP7 “Capacities” Specific Programme through grant agreement number 262552, MaRINET. Project Periodic Report. 2nd Period: October 2012 – March 2014 inclusive....

  20. The Living Periodic Table

    Science.gov (United States)

    Nahlik, Mary Schrodt

    2005-01-01

    To help make the abstract world of chemistry more concrete eighth-grade students, the author has them create a living periodic table that can be displayed in the classroom or hallway. This display includes information about the elements arranged in the traditional periodic table format, but also includes visual real-world representations of the…