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Sample records for nonlinearity vanishes coarsening

  1. Wave instabilities in nonlinear Schrödinger systems with non vanishing background

    KAUST Repository

    Trillo, Stefano

    2014-01-01

    We investigate wave collapse in the generalized nonlinear Schrödinger (NLS) equation and in the presence of a non vanishing background. Through the use of virial identities, we establish a new criterion for blow-up.

  2. BOUNDARY LAYER AND VANISHING DIFFUSION LIMIT FOR NONLINEAR EVOLUTION EQUATIONS

    Institute of Scientific and Technical Information of China (English)

    彭艳

    2014-01-01

    In this paper, we consider an initial-boundary value problem for some nonlinear evolution equations with damping and diffusion. The main purpose is to investigate the boundary layer effect and the convergence rates as the diffusion parameterαgoes to zero.

  3. Conservation Laws for the Derivative Nonlinear Schr(o)dinger Equation with Non-vanishing Boundary Conditions

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiang-Jun; HOU Li-Jie; LAM Wa Kun

    2005-01-01

    @@ Conservation laws for the derivative nonlinear Schr(o)dinger equation with non-vanishing boundary conditions are derived, based on the recently developed inverse scattering transform using the affine parameter technique.

  4. Remarks on a Class of Nonlinear Schrödinger Equations with Potential Vanishing at Infinity

    Directory of Open Access Journals (Sweden)

    Hongbo Zhu

    2013-01-01

    Full Text Available We study the following nonlinear Schrödinger equation −Δu+V(xu=K(xf(u,  x∈ℝN,  u∈H1(ℝN, where the potential V(x vanishes at infinity. Working in weighted Sobolev space, we obtain the ground states of problem ( under a Nahari type condition. Furthermore, if V(x,K(x are radically symmetric with respect to x∈ℝN, it is shown that problem ( has a positive solution with some more general growth conditions of the nonlinearity. Particularly, if f(u=up, then the growth restriction σ≤p≤N+2/N-2 in Ambrosetti et al. (2005 can be relaxed to σ~≤p≤N+2/N-2, where σ~<σ if 0<β<α<2.

  5. A new smooth robust control design for uncertain nonlinear systems with non-vanishing disturbances

    Science.gov (United States)

    Xian, Bin; Zhang, Yao

    2016-06-01

    In this paper, we consider the control problem for a general class of nonlinear system subjected to uncertain dynamics and non-varnishing disturbances. A smooth nonlinear control algorithm is presented to tackle these uncertainties and disturbances. The proposed control design employs the integral of a nonlinear sigmoid function to compensate the uncertain dynamics, and achieve a uniformly semi-global practical asymptotic stable tracking control of the system outputs. A novel Lyapunov-based stability analysis is employed to prove the convergence of the tracking errors and the stability of the closed-loop system. Numerical simulation results on a two-link robot manipulator are presented to illustrate the performance of the proposed control algorithm comparing with the layer-boundary sliding mode controller and the robust of integration of sign of error control design. Furthermore, real-time experiment results for the attitude control of a quadrotor helicopter are also included to confirm the effectiveness of the proposed algorithm.

  6. Wave instabilities in the presence of non vanishing background in nonlinear Schrödinger systems.

    Science.gov (United States)

    Trillo, S; Gongora, J S Totero; Fratalocchi, A

    2014-12-03

    We investigate wave collapse ruled by the generalized nonlinear Schrödinger (NLS) equation in 1+1 dimensions, for localized excitations with non-zero background, establishing through virial identities a new criterion for blow-up. When collapse is arrested, a semiclassical approach allows us to show that the system can favor the formation of dispersive shock waves. The general findings are illustrated with a model of interest to both classical and quantum physics (cubic-quintic NLS equation), demonstrating a radically novel scenario of instability, where solitons identify a marginal condition between blow-up and occurrence of shock waves, triggered by arbitrarily small mass perturbations of different sign.

  7. Wave instabilities in the presence of non vanishing background in nonlinear Schrödinger systems

    KAUST Repository

    Trillo, S.

    2014-12-03

    We investigate wave collapse ruled by the generalized nonlinear Schrödinger (NLS) equation in 1+1 dimensions, for localized excitations with non-zero background, establishing through virial identities a new criterion for blow-up. When collapse is arrested, a semiclassical approach allows us to show that the system can favor the formation of dispersive shock waves. The general findings are illustrated with a model of interest to both classical and quantum physics (cubic-quintic NLS equation), demonstrating a radically novel scenario of instability, where solitons identify a marginal condition between blow-up and occurrence of shock waves, triggered by arbitrarily small mass perturbations of different sign.

  8. Mathematical Analysis of a Coarsening Model with Local Interactions

    Science.gov (United States)

    Helmers, Michael; Niethammer, Barbara; Velázquez, Juan J. L.

    2016-10-01

    We consider particles on a one-dimensional lattice whose evolution is governed by nearest-neighbor interactions where particles that have reached size zero are removed from the system. Concentrating on configurations with infinitely many particles, we prove existence of solutions under a reasonable density assumption on the initial data and show that the vanishing of particles and the localized interactions can lead to non-uniqueness. Moreover, we provide a rigorous upper coarsening estimate and discuss generic statistical properties as well as some non-generic behavior of the evolution by means of heuristic arguments and numerical observations.

  9. A General Vanishing Theorem

    Indian Academy of Sciences (India)

    F Laytimi; W Nahm

    2013-11-01

    Let be a vector bundle and be a line bundle over a smooth projective variety . In this article, we give a condition for the vanishing of Dolbeault cohomology groups of the form $H^{p,q}(X, S^ E \\otimes {\\wedge}^ E \\otimes L)$ when $S^{+} E \\otimes L$ is ample. This condition is shown to be invariant under the interchange of and . The optimality of this condition is discussed for some parameter values.

  10. Vanishing in Plain Sight

    Directory of Open Access Journals (Sweden)

    Williams, Grace Alexandra

    2014-12-01

    Full Text Available Playfully negotiating the historical constructs of theatrical vanishing and its disturbingly female trappings this paper centers on the creation of Bautier de Kolta’s l’Escamotage D’une Dame, an illusion used to screen the anxieties of the male British populous, irked by a buoyant surplus in unmarried, white, middle class women, in the late 1880s. Introducing texts such as W. R Greg’s Why are women Redundant? This paper makes ever more apparent the political, violent and sexual connotations of the female body in magical feats of performative disappearance. From the photographic curios of hidden mothers to the dark room of the séance, the conversation unfurls around the many forms of female vanishing, culminating in a discussion of the contemporary artwork Escamotage (Grace A Williams, 2015 that takes the Persian rug as both a motif of magical vanishing and a tool for the exposure of form. This paper was originally delivered as a performance from within a ‘Zig-Zag’ illusion box, in collaboration with artist David Cheeseman. The first critical analysis of women’s role within magical illusions, delivered by a female artist from within a magical prop that continues to dismember female bodies for entertainment in the contemporary magic market.

  11. The vanishing effect of finance on growth

    OpenAIRE

    Gründler, Klaus

    2015-01-01

    This paper investigates the causes of the "vanishing effect of finance" detected in recent studies. The results highlight that the negative effect of the financial system on growth is mainly driven by advanced economies, whereas finance is still beneficial for income increases in developing countries. The reason is that finance and growth are associated via a nonlinear relationship, which is due to a fundamental change in the transmission mechanism of finance across different levels of econom...

  12. Quantum metrology in coarsened measurement reference

    Science.gov (United States)

    Xie, Dong; Xu, Chunling; Wang, An Min

    2017-01-01

    We investigate the role of coarsened measurement reference, which originates from the coarsened reference time and basis, in quantum metrology. When the measurement is based on one common reference basis, the disadvantage of coarsened measurement can be removed by symmetry. Owing to the coarsened reference basis, the entangled state cannot perform better than the product state for a large number of probe particles in estimating the phase. Given a finite uncertainty of the coarsened reference basis, the optimal number of probe particles is obtained. Finally, we prove that the maximally entangled state always achieves better frequency precision in the case of non-Markovian dephasing than that in the case of Markovian dephasing. The product state is more resistant to the interference of the coarsened reference time than the entangled state.

  13. The vanishing volume of D = 4 superspace

    Energy Technology Data Exchange (ETDEWEB)

    Bossard, Guillaume, E-mail: bossard@cpht.polytechnique.f [Ecole Polytechnique (CNRS), Palaiseau Cedex (France). Centre de Physique Theorique; Howe, P.S., E-mail: paul.howe@kcl.ac.u [University of London (United Kingdom). King' s College. Dept. of Mathematics; Stelle, K.S., E-mail: stelle@imperial.ac.u [Imperial College London (United Kingdom). Theoretical Physics Group; Vanhove, Pierre, E-mail: pierre.vanhove@cea.f [University of California, Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics

    2011-07-01

    The volume of on-shell D = 4, N = 8 superspace is shown to vanish. Despite this, it is shown that there is a fully supersymmetric and duality-invariant candidate {nabla}{sup 8}R{sup 4} counterterm corresponding to an anticipated seven-loop logarithmic divergence in D = 4. We construct this counterterm explicitly and also give the complete nonlinear extension of the 1=8-BPS {nabla}{sup 6}R{sup 4} invariant. Similar results are derived for N = 4; 5 and 6. (author)

  14. Advanced Coarsening Schemes for Graph Partitioning

    CERN Document Server

    Safro, Ilya; Schulz, Christian

    2012-01-01

    The graph partitioning problem is widely used and studied in many practical and theoretical applications. The multilevel strategies represent today one of the most effective and efficient generic frameworks for solving this problem on large-scale graphs. Most of the attention in designing the multilevel partitioning frameworks has been on the refinement phase. In this work we focus on the coarsening phase, which is responsible for creating structurally similar to the original but smaller graphs. We compare different matching- and AMG-based coarsening schemes, experiment with the algebraic distance between nodes, and demonstrate computational results on several classes of graphs that emphasize the running time and quality advantages of different coarsenings.

  15. Cellular automata modelling of austenite grain coarsening during reheating--Ⅰ.Normal grain coarsening

    Institute of Scientific and Technical Information of China (English)

    Wanhua Yu; E.J. Palmiere; S.P. Banks; Jingtao Han

    2004-01-01

    A two-dimensional cellular automaton (CA) model has been developed for the description of the normal grain coarsening process. The probabilistic CA method incorporating Moore's definition of the neighbourhood is used to simulate the normal grain coarsening process with a new transition rule. The model simulates the grain coarsening process in as much detail that is possible,from the point of initial nucleation to subsequent coarsening with computational times. The unique result is that the grain coarsening speed can be controlled by the specific method, this result is vital to model the grain coarsening quantitatively. In order to make this model valid, experimental work has been done to provide solid evidence for this model. Comparison of the modelling result and the experimental result has been carried out.

  16. Transition to coarsening for confined one-dimensional interfaces with bending rigidity

    Science.gov (United States)

    Le Goff, Thomas; Politi, Paolo; Pierre-Louis, Olivier

    2015-08-01

    We discuss the nonlinear dynamics and fluctuations of interfaces with bending rigidity under the competing attractions of two walls with arbitrary permeabilities. This system mimics the dynamics of confined membranes. We use a two-dimensional hydrodynamic model, where membranes are effectively one-dimensional objects. In a previous work [T. Le Goff et al., Phys. Rev. E 90, 032114 (2014), 10.1103/PhysRevE.90.032114], we have shown that this model predicts frozen states caused by bending rigidity-induced oscillatory interactions between kinks (or domain walls). We here demonstrate that in the presence of tension, potential asymmetry, or thermal noise, there is a finite threshold above which frozen states disappear, and perpetual coarsening is restored. Depending on the driving force, the transition to coarsening exhibits different scenarios. First, for membranes under tension, small tensions can only lead to transient coarsening or partial disordering, while above a finite threshold, membrane oscillations disappear and perpetual coarsening is found. Second, potential asymmetry is relevant in the nonconserved case only, i.e., for permeable walls, where it induces a drift force on the kinks, leading to a fast coarsening process via kink-antikink annihilation. However, below some threshold, the drift force can be balanced by the oscillatory interactions between kinks, and frozen adhesion patches can still be observed. Finally, at long times, noise restores coarsening with standard exponents depending on the permeability of the walls. However, the typical time for the appearance of coarsening exhibits an Arrhenius form. As a consequence, a finite noise amplitude is needed in order to observe coarsening in observable time.

  17. A Vanishing Star Revisited

    Science.gov (United States)

    1999-07-01

    VLT Observations of an Unusual Stellar System Reinhold Häfner of the Munich University Observatory (Germany) is a happy astronomer. In 1988, when he was working at a telescope at the ESO La Silla observatory, he came across a strange star that suddenly vanished off the computer screen. He had to wait for more than a decade to get the full explanation of this unusual event. On June 10-11, 1999, he observed the same star with the first VLT 8.2-m Unit Telescope (ANTU) and the FORS1 astronomical instrument at Paranal [1]. With the vast power of this new research facility, he was now able to determine the physical properties of a very strange stellar system in which two planet-size stars orbit each other. One is an exceedingly hot white dwarf star , weighing half as much as the Sun, but only twice as big as the Earth. The other is a much cooler and less massive red dwarf star , one-and-a-half times the size of planet Jupiter. Once every three hours, the hot star disappears behind the other, as seen from the Earth. For a few minutes, the brightness of the system drops by a factor of more than 250 and it "vanishes" from view in telescopes smaller than the VLT. A variable star named NN Serpentis ESO PR Photo 30a/99 ESO PR Photo 30a/99 [Preview - JPEG: 400 x 468 pix - 152k] [Normal - JPEG: 800 x 936 pix - 576k] [High-Res - JPEG: 2304 x 2695 pix - 4.4M] Caption to ESO PR Photo 30a/99 : The sky field around the 17-mag variable stellar system NN Serpentis , as seen in a 5 sec exposure through a V(isual) filter with VLT ANTU and FORS1. It was obtained just before the observation of an eclipse of this unsual object and served to centre the telescope on the corresponding sky position. The field shown here measures 4.5 x 4.5 armin 2 (1365 x 1365 pix 2 ; 0.20 arcsec/pix). The field is somewhat larger than that shown in Photo 30b/99 and has the same orientation to allow comparison: North is about 20° anticlockwise from the top and East is 90° clockwise from that direction. The

  18. Omaha Survival: A Vanishing Indian Tribe that Would Not Vanish.

    Science.gov (United States)

    Ridington, Robin

    1987-01-01

    The Omaha have kept themselves together as a people throughout the century when they were expected to have vanished. They are strong today precisely because they have remained emotionally bound to an Indian identity, taking elements of white culture that are of benefit while retaining the traditional cultural spirit. (JHZ)

  19. Compatible Relaxation and Coarsening in Algebraic Multigrid

    Energy Technology Data Exchange (ETDEWEB)

    Brannick, J J; Falgout, R D

    2009-09-22

    We introduce a coarsening algorithm for algebraic multigrid (AMG) based on the concept of compatible relaxation (CR). The algorithm is significantly different from standard methods, most notably because it does not rely on any notion of strength of connection. We study its behavior on a number of model problems, and evaluate the performance of an AMG algorithm that incorporates the coarsening approach. Lastly, we introduce a variant of CR that provides a sharper metric of coarse-grid quality and demonstrate its potential with two simple examples.

  20. PETN Coarsening - Predictions from Accelerated Aging Data

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, Amitesh [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gee, Richard H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-03-30

    Ensuring good ignition properties over long periods of time necessitates maintaining a good level of porosity in powders of initiator materials and preventing particle coarsening. To simulate porosity changes of such powder materials over long periods of time a common strategy is to perform accelerated aging experiments over shorter time spans at elevated temperatures. In this paper we examine historical accelerated-aging data on powders of Pentaerythritol Tetranitrate (PETN), an important energetic material, and make predictions for long-term aging under ambient conditions. Lastly, we develop an evaporation-condensation- based model to provide some mechanistic understanding of the coarsening process.

  1. STU attractors from vanishing concurrence

    CERN Document Server

    Lévay, Péter

    2010-01-01

    Concurrence is an entanglement measure characterizing the {\\it mixed} state bipartite correlations inside of a pure state of an $n$-qubit system. We show that after organizing the charges and the moduli in the STU model of $N=2$, $d=4$ supergravity to a three-qubit state, for static extremal spherically symmetric BPS black hole solutions the vanishing condition for all of the bipartite concurrences on the horizon is equivalent to the attractor equations. As a result of this the macroscopic black hole entropy given by the three-tangle can be reinterpreted as a linear entropy characterizing the {\\it pure} state entanglement for an arbitrary bipartite split. Both for the BPS and non-BPS cases explicit expressions for the concurrences are obtained, with their vanishing on the horizon is demonstrated.

  2. Structural refinement and coarsening in deformed metals

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Xing, Q.

    2005-01-01

    The microstructural refinement by plastic deformation is analysed in terms of key parameters, the spacing between and the misorientation angle across the boundaries subdividing the structure. Coarsening of such structures by annealing is also characterised. For both deformed and annealed structur...

  3. On a relation between roughening and coarsening

    Science.gov (United States)

    Corberi, Federico; Lippiello, Eugenio; Zannetti, Marco

    2016-10-01

    We argue that a strict relation exists between two in principle unrelated quantities: The size of the growing domains in a coarsening system, and the kinetic roughening of an interface. This relation is confirmed by extensive simulations of the Ising model with different forms of quenched disorder, such as random bonds, random fields andstochastic dilution.

  4. Direct Observation of "Pac-Man" Coarsening.

    Science.gov (United States)

    Yu, X X; Gulec, A; Yoon, A; Zuo, J M; Voorhees, P W; Marks, L D

    2017-08-09

    We report direct observation of a "Pac-Man" like coarsening mechanism of a self-supporting thin film of nickel oxide. The ultrathin film has an intrinsic morphological instability due to surface stress leading to the development of local thicker regions at step edges. Density functional theory calculations and continuum modeling of the elastic instability support the model for the process.

  5. Densification and grain coarsening of melting snow

    Institute of Scientific and Technical Information of China (English)

    周石硚; 中尾正义; 桥本重将; 坂井亚规子; 成田英器; 石川信敬

    2003-01-01

    A field work was conducted at Moshiri in Japan.The work included intensive snow pit work, taking snow grain photos, recording snow and air temperatures, as well as measuring snow water content.By treating the snow as a viscous fluid, it is found that the snow compactive viscosity decreases as the density increases, which is opposite to the relation for dry snow.Based on the measurements of snow grain size, it is shown that, similar to the water-saturated snow, the frequency distributions of grain size at different times almost have the same shape.This reveals that the water-unsaturated melting snow holds the same grain-coarsening behavior as the water-saturated snow does.It is also shown that the water-unsaturated melting snow coarsens much more slowly than the water-saturated snow.The C value, which is the viscosity when the snow density is zero, is related to the mean grain size and found to decrease with increasing grain size.The decreasing rate of C value increases with decreasing grain-coarsening rate.

  6. Grain coarsening of calcite: Fundamental mechanisms and biogenic inhibition

    DEFF Research Database (Denmark)

    Schultz, Logan Nicholas

    In a saturated solution, submicrometer calcite (CaCO3) crystals recrystallize and coarsen to minimize surface area. The thermodynamic driving force is described by the Gibbs-Thomson equation, but the rates and mechanism are poorly understood. Calcite grain coarsening has many implications...... in industry and nature, but the specific focus of this research project was to understand how small, biogenic calcite particles in chalk have resisted grain coarsening for over 60 million years in saturated reservoir fluids. A new method was developed to produce pure calcite powder that has submicrometer...... coarsening – small grains coarsen by aggregation at high temperatures, followed by Ostwald ripening. Alginate, a model for the acidic polysaccharides produced by coccolithiphores, inhibited coarsening at a steady rate. A Pseudomonas aeruginosa biofilm preserved particles for at least 60 days before...

  7. New Hydrodynamic Mechanism for Drop Coarsening

    CERN Document Server

    Nikolayev, Vadim; Guenoun, Patrick

    2016-01-01

    We discuss a new mechanism of drop coarsening due to coalescence only, which describes the late stages of phase separation in fluids. Depending on the volume fraction of the minority phase, we identify two different regimes of growth, where the drops are interconnected and their characteristic size grows linearly with time, and where the spherical drops are disconnected and the growth follows (time) 1/3. The transition between the two regimes is sharp and occurs at a well defined volume fraction of order 30%.

  8. Coarsening dynamics of zero-range processes

    Science.gov (United States)

    Godrèche, Claude; Drouffe, Jean-Michel

    2017-01-01

    We consider a class of zero-range processes exhibiting a condensation transition in the stationary state, with a critical single-site distribution decaying faster than a power law. We present the analytical study of the coarsening dynamics of the system on the complete graph, both at criticality and in the condensed phase. In contrast with the class of zero-range processes with critical single-site distribution decaying as a power law, in the present case the role of finite-time corrections is essential for the understanding of the approach to scaling.

  9. Coarsening kinetics of fine-scale microstructures in deformed materials

    DEFF Research Database (Denmark)

    Yu, Tianbo; Hansen, Niels

    2016-01-01

    model is not applicable in an analysis of coarsening of nanostructured materials. Our analysis also shows that an initial low thermal stability of nanostructured materials is inherently related to their large boundary area per unit volume and their high content of stored energy, providing a large...... and driving force. We propose a unified coarsening model, which is based on recovery kinetics and allows the apparent activation energy to change during coarsening. The model is successfully applied to the three coarsening processes in different materials of different structural morphology and scale, showing...

  10. Grain coarsening in polymineralic contact metamorphic carbonate rocks: The role of different physical interactions during coarsening

    DEFF Research Database (Denmark)

    Brodhag, Sabine; Herwegh, Marco; Berger, Alfons

    2011-01-01

    ) and microstructures with considerable second-phase volume fractions of up to 0.5. The variations might be of general validity for any polymineralic rock, which undergoes grain coarsening during metamorphism. The new findings are important for a better understanding of the initiation of strain localization based...... on the activation of grain size dependent deformation mechanisms....

  11. Coarsening at random: characterizations, conjectures and counter-examples

    NARCIS (Netherlands)

    Gill, R.D.; Laan, M.J. van der; Robins, J.M.

    1997-01-01

    The notion of coarsening at random CAR was introduced by Heitjan and Rubin to describe the most general form of randomly grouped censored or missing data for which the coarsening mechanism can be ignored when making likelihoodbased inference about the parameters of the distribution of the variable

  12. Practical Issues in Estimating Achievement Gaps from Coarsened Data

    Science.gov (United States)

    Reardon, Sean F.; Ho, Andrew D.

    2015-01-01

    In an earlier paper, we presented methods for estimating achievement gaps when test scores are coarsened into a small number of ordered categories, preventing fine-grained distinctions between individual scores. We demonstrated that gaps can nonetheless be estimated with minimal bias across a broad range of simulated and real coarsened data…

  13. Coarsening Rates of Bicontinuous Structures in Polymer Mixtures

    NARCIS (Netherlands)

    Scholten, E.; Sagis, L.M.C.; Linden, van der E.

    2005-01-01

    We discuss the coarsening of domains in bicontinuous structure of aqueous polymer mixtures, driven by hydrodynamic flow. Taking into account the bending energy as a contribution to the interfacial energy, we derive a general expression for the coarsening rate in these mixtures. Examining the

  14. Semi-coarsening multigrid methods for parallel computing

    Energy Technology Data Exchange (ETDEWEB)

    Jones, J.E.

    1996-12-31

    Standard multigrid methods are not well suited for problems with anisotropic coefficients which can occur, for example, on grids that are stretched to resolve a boundary layer. There are several different modifications of the standard multigrid algorithm that yield efficient methods for anisotropic problems. In the paper, we investigate the parallel performance of these multigrid algorithms. Multigrid algorithms which work well for anisotropic problems are based on line relaxation and/or semi-coarsening. In semi-coarsening multigrid algorithms a grid is coarsened in only one of the coordinate directions unlike standard or full-coarsening multigrid algorithms where a grid is coarsened in each of the coordinate directions. When both semi-coarsening and line relaxation are used, the resulting multigrid algorithm is robust and automatic in that it requires no knowledge of the nature of the anisotropy. This is the basic multigrid algorithm whose parallel performance we investigate in the paper. The algorithm is currently being implemented on an IBM SP2 and its performance is being analyzed. In addition to looking at the parallel performance of the basic semi-coarsening algorithm, we present algorithmic modifications with potentially better parallel efficiency. One modification reduces the amount of computational work done in relaxation at the expense of using multiple coarse grids. This modification is also being implemented with the aim of comparing its performance to that of the basic semi-coarsening algorithm.

  15. Vanishing point: Scale independence in geomorphological hierarchies

    Science.gov (United States)

    Phillips, Jonathan D.

    2016-08-01

    Scale linkage problems in geosciences are often associated with a hierarchy of components. Both dynamical systems perspectives and intuition suggest that processes or relationships operating at fundamentally different scales are independent with respect to influences on system dynamics. But how far apart is "fundamentally different"-that is, what is the "vanishing point" at which scales are no longer interdependent? And how do we reconcile that with the idea (again, supported by both theory and intuition) that we can work our way along scale hierarchies from microscale to planetary (and vice-versa)? Graph and network theory are employed here to address these questions. Analysis of two archetypal hierarchical networks shows low algebraic connectivity, indicating low levels of inferential synchronization. This explains the apparent paradox between scale independence and hierarchical linkages. Incorporating more hierarchical levels results in an increase in complexity or entropy of the network as a whole, but at a nonlinear rate. Complexity increases as a power α of the number of levels in the hierarchy, with α < 1 and usually ≤ 0.6. However, algebraic connectivity decreases at a more rapid rate. Thus, the ability to infer one part of the hierarchical network from other level decays rapidly as more levels are added. Relatedness among system components decreases with differences in scale or resolution, analogous to distance decay in the spatial domain. These findings suggest a strategy of identifying and focusing on the most important or interesting scale levels, rather than attempting to identify the smallest or largest scale levels and work top-down or bottom-up from there. Examples are given from soil geomorphology and karst flow networks.

  16. Non-trivial exponents in coarsening phenomena

    Science.gov (United States)

    Derrida, B.

    1997-02-01

    One of the simplest examples of stochastic automata is the Glauber dynamics of ferromagnetic spin models such as Ising or Potts models. At zero temperature, if the initial condition is random, one observes a pattern of growing domains with a characteristic size which increases with time like t {1}/{2}. In this self-similar regime, the fraction of spins which never flip up to time t decreases like t- θ where the exponent θ is non-trivial and depends both on the number q of states of the Potts model and on the dimension of space. This exponent can be calculated exactly in one dimension. Similar non-trivial exponents are also present in even simpler models of coarsening, where the dynamical rule is deterministic.

  17. Phase field modeling of dendritic coarsening during isothermal

    Directory of Open Access Journals (Sweden)

    Zhang Yutuo

    2011-08-01

    Full Text Available Dendritic coarsening in Al-2mol%Si alloy during isothermal solidification at 880K was investigated by phase field modeling. Three coarsening mechanisms operate in the alloy: (a melting of small dendrite arms; (b coalescence of dendrites near the tips leading to the entrapment of liquid droplets; (c smoothing of dendrites. Dendrite melting is found to be dominant in the stage of dendritic growth, whereas coalescence of dendrites and smoothing of dendrites are dominant during isothermal holding. The simulated results provide a better understanding of dendrite coarsening during isothermal solidification.

  18. Grain coarsening of calcite: Fundamental mechanisms and biogenic inhibition

    DEFF Research Database (Denmark)

    Schultz, Logan Nicholas

    grain diameter: The small particle size was similar to coccolith elements in chalk. Calcite was aged in saturated solutions for up to 261 days at temperatures up to 200 °C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and BET surface area data showed fundamental insight into grain...... coarsening – small grains coarsen by aggregation at high temperatures, followed by Ostwald ripening. Alginate, a model for the acidic polysaccharides produced by coccolithiphores, inhibited coarsening at a steady rate. A Pseudomonas aeruginosa biofilm preserved particles for at least 60 days before...

  19. Coupling between drainage and coarsening in wet foam

    Indian Academy of Sciences (India)

    S Saha; S Bhaumik; A Roy

    2009-06-01

    Drainage and coarsening are two coupled phenomena during the evolution of wet foam. We show the variation in the growth rate of bubble size, along the height in a column of Gillette shaving foam, by microscope imaging. Simultaneously, the drainage of liquid at the same heights has been investigated by Raman spectroscopic measurements. The observations made in these two sets of experiments indicate the coupling between drainage and coarsening in wet foam. We could explain the correlation between our observed data on drainage and coarsening by the empirical relation, proposed by others, in the literature.

  20. Topology Induced Coarsening in Language Games

    CERN Document Server

    Baronchelli, A; Dall'Asta, L; Loreto, V

    2006-01-01

    We investigate how very large populations are able to reach a global consensus, out of local "microscopic" interaction rules, in the framework of a recently introduced class of models of semiotic dynamics, the so-called Naming Game. We compare in particular the convergence mechanism for interacting agents embedded in a low-dimensional lattice with respect to the mean-field case. We highlight that in low-dimensions consensus is reached through a coarsening process which requires less cognitive effort of the agents, with respect to the mean-field case, but takes longer to complete. In 1-d the dynamics of the boundaries is mapped onto a truncated Markov process from which we analytically computed the diffusion coefficient. More generally we show that the convergence process requires a memory per agent scaling as N and lasts a time N^{1+2/d} in dimension d<5 (d=4 being the upper critical dimension), while in mean-field both memory and time scale as N^{3/2}, for a population of N agents. We present analytical a...

  1. A coarsening model for coherent precipitates

    Energy Technology Data Exchange (ETDEWEB)

    McCormack, Mark Thomas [Univ. of California, Berkeley, CA (United States)

    1991-12-01

    The morphological evolution of coherent inclusions in elastic media is studied in two-dimensions. The inclusions are simple dilations with isotropic surface energy in a system with homogeneous elastic constants of negative anisotropy. The equilibrium sizes at which a circular inclusion transforms to a rectangle or square, and at which a square splits into a doublet or quartet of separated inclusions are computed analytically. A finite-element model is then constructed to simulate the evolution of an arbitrary distribution of inclusions along the minimum-energy path. In the model, the circle evolves into a square, which splits into a doublet by hollowing from its center, or, if this is forbidden, by drawing in a perturbation on its surface. The sizes at which shapes spontaneously transform are compared to the equilibrium values. Finally, the simulation is used to study the evolution of a random distribution of inclusions. The first metastable state assumed by the distribution depends on the elastic interaction, surface energy and areal fraction of the inclusion phase through a single dimensionless parameter that groups these three effects. Results are compared to prior theoretical and experimental work on coarsening patterns in three dimensions.

  2. A novel coarsening mechanism of droplets in immiscible fluid mixtures

    OpenAIRE

    Shimizu, Ryotaro; Tanaka, Hajime

    2015-01-01

    In our daily lives, after shaking a salad dressing, we see the coarsening of oil droplets suspended in vinegar. Such a demixing process is observed everywhere in nature and also of technological importance. For a case of high droplet density, domain coarsening proceeds with interdroplet collisions and the resulting coalescence. This phenomenon has been explained primarily by the so-called Brownian coagulation mechanism: stochastic thermal forces exerted by molecules induce random motion of in...

  3. Coarsening in high volume fraction nickel-base alloys

    Science.gov (United States)

    Mackay, R. A.; Nathal, M. V.

    1990-01-01

    The coarsening behavior of the gamma-prime precipitate has been examined in high volume fraction nickel-base alloys aged at elevated temperatures for times of up to 5000 h. Although the cube rate law was observed during coarsening, none of the presently available coarsening theories showed complete agreement with the experimental particle size distributions (PSDs). These discrepancies were thought to be due to elastic coherency strains which were not considered by the available models. Increasing the Mo content significantly influenced the PSDs and decreased the coarsening rate of the gamma-prime cubes, as a result of increasing the magnitude of the lattice mismatch. After extended aging times, the gamma-prime cubes underwent massive coalescence into plates at a rate which was much faster than the cuboidal coarsening rate. Once the gamma-prime plates were formed, further coarsening was not observed, and this stabilization of the microstructure was attributed to the development of dislocation networks at the gamma-gamma-prime interfaces.

  4. Evolution of Local Microstructures: Spatial Instabilities in Coarsening Clusters

    Science.gov (United States)

    2003-01-01

    Diffusion-limited capillarity-driven coarsening of precipitates is an important and intensively studied phenomenon. The classic coarsening theory developed by Lifshitz and Syozov and Wagner (LSW theory) is limited to infinitesimally small volume fractions, V(sub nu), therefore neglects all direct interparticle interactions. This work uses modeling and holographic imaging to compare coarsening rates in "high" volume fraction versus low volume fraction microstructures by observing mixed-dimensional droplets (spherical caps on a surface coarsening by two-dimensional diffusion) during ground-based investigations. The method involves filling a cell with selected homogeneous parent phase, and cooling below the consolute temperature to the isopycnic temperature in the two-phase region of a monotectic system. A microgravity holographic experiment is required for three-dimensional observations to minimize sedimentation during long-term coarsening. Determination of sizes and positions of the many droplets in the holographic images requires automation. We have developed software for automated data analysis, and demonstrated good agreement between regenerated maps and scaled photographs of the original holograms for mixed dimensional coarsening. The results of these experiments were presented in a formal microgravity Science Concept Review (SCR) on December 18, 2000.

  5. Generalized linear models with coarsened covariates: a practical Bayesian approach.

    Science.gov (United States)

    Johnson, Timothy R; Wiest, Michelle M

    2014-06-01

    Coarsened covariates are a common and sometimes unavoidable phenomenon encountered in statistical modeling. Covariates are coarsened when their values or categories have been grouped. This may be done to protect privacy or to simplify data collection or analysis when researchers are not aware of their drawbacks. Analyses with coarsened covariates based on ad hoc methods can compromise the validity of inferences. One valid method for accounting for a coarsened covariate is to use a marginal likelihood derived by summing or integrating over the unknown realizations of the covariate. However, algorithms for estimation based on this approach can be tedious to program and can be computationally expensive. These are significant obstacles to their use in practice. To overcome these limitations, we show that when expressed as a Bayesian probability model, a generalized linear model with a coarsened covariate can be posed as a tractable missing data problem where the missing data are due to censoring. We also show that this model is amenable to widely available general-purpose software for simulation-based inference for Bayesian probability models, providing researchers a very practical approach for dealing with coarsened covariates.

  6. [Rapidly vanishing hip--a mystery].

    Science.gov (United States)

    Keren, Yaniv; Sigal, Amit; Greental, Arnan; Vlodavsky, Euvgeni; Soudry, Michael; Militianu, Daniela

    2013-01-01

    Rapidly destructive hip disease is a rare condition, the cause of which is yet to be clarified, and is described in the literature by scant case reports. The disease was first described by Forestier in 1957, and since then many names have been proposed to describe the rapid vanishing of the femoral head, and occasionally the acetabulum. This condition initially represents as acute hip pain, and rapidly progresses to complete vanishing of the proximal femur, within a few months. We briefly discuss the literature regarding this phenomenon, and describe a case of a female patient who suffered from complete disappearance of the femoral head within 9 weeks.

  7. Maps with vanishing denominator and their applications

    Directory of Open Access Journals (Sweden)

    Nicolò Pecora

    2016-08-01

    Full Text Available We survey the theoretical findings and a set of applications in several different fields concerning two-dimensional maps characterized by a vanishing denominator. This family of maps, and the related dynamic properties, were originally brought to the attention of the researchers through their appearance in an economic application. Nowadays such maps have also been used in other research areas such as ecology or biology confirming a broader application of the theoretical results about plane maps with vanishing denominator to various research areas.

  8. Boundedness and vanishing of solutions for a forced delay dynamic equation

    Directory of Open Access Journals (Sweden)

    Anderson Douglas R

    2006-01-01

    Full Text Available We give conditions under which all solutions of a time-scale first-order nonlinear variable-delay dynamic equation with forcing term are bounded and vanish at infinity, for arbitrary time scales that are unbounded above. A nontrivial example illustrating an application of the results is provided.

  9. Electromagnetic fields with vanishing scalar invariants

    CERN Document Server

    Ortaggio, Marcello

    2015-01-01

    We determine the class of $p$-forms $F$ which possess vanishing scalar invariants (VSI) at arbitrary order in a $n$-dimensional spacetime. Namely, we prove that $F$ is VSI if and only if it is of type N, its multiple null direction $l$ is "degenerate Kundt", and $\

  10. Natural occupation numbers: when do they vanish?

    Science.gov (United States)

    Giesbertz, K J H; van Leeuwen, R

    2013-09-14

    The non-vanishing of the natural orbital (NO) occupation numbers of the one-particle density matrix of many-body systems has important consequences for the existence of a density matrix-potential mapping for nonlocal potentials in reduced density matrix functional theory and for the validity of the extended Koopmans' theorem. On the basis of Weyl's theorem we give a connection between the differentiability properties of the ground state wavefunction and the rate at which the natural occupations approach zero when ordered as a descending series. We show, in particular, that the presence of a Coulomb cusp in the wavefunction leads, in general, to a power law decay of the natural occupations, whereas infinitely differentiable wavefunctions typically have natural occupations that decay exponentially. We analyze for a number of explicit examples of two-particle systems that in case the wavefunction is non-analytic at its spatial diagonal (for instance, due to the presence of a Coulomb cusp) the natural orbital occupations are non-vanishing. We further derive a more general criterium for the non-vanishing of NO occupations for two-particle wavefunctions with a certain separability structure. On the basis of this criterium we show that for a two-particle system of harmonically confined electrons with a Coulombic interaction (the so-called Hookium) the natural orbital occupations never vanish.

  11. Vanishing voices from Russia & Eastern Europe

    NARCIS (Netherlands)

    de Graaf, T.

    2016-01-01

    These recordings were digitised as part of the Endangered Archives Programme (EAP) project EAP347: ‘Vanishing voices from the Uralic world: sound recordings for archives in Russia (in particular Udmurtia), Estonia, Finland and Hungary’. The project digitised sound collections from the Uralic speakin

  12. Transverse correlation vanishing due to phase aberrations

    CSIR Research Space (South Africa)

    Godin, T

    2011-06-01

    Full Text Available The concept of transverse correlation vanishing, between the fraction of power contained in the centre and wings of a probe beam, recently introduced [Opt. Commun. 282 (2009) 3854–3858] is important to be considered when measuring the effective...

  13. Vanishing Vierbein in Gauge Theories of Gravitation

    CERN Document Server

    Jadczyk, A

    1999-01-01

    We discuss the problem of a degenerate vierbein in the framework of gauge theories of gravitation (thus including torsion). We discuss two examples: Hanson-Regge gravitational instanton and Einstein-Rose bridge.We argue that a region of space-time with vanishing vierbein but smooth principal connection can be, in principle, detected by scattering experiments.

  14. Moose models with vanishing $S$ parameter

    CERN Document Server

    Casalbuoni, R; Dominici, Daniele

    2004-01-01

    In the linear moose framework, which naturally emerges in deconstruction models, we show that there is a unique solution for the vanishing of the $S$ parameter at the lowest order in the weak interactions. We consider an effective gauge theory based on $K$ SU(2) gauge groups, $K+1$ chiral fields and electroweak groups $SU(2)_L$ and $U(1)_Y$ at the ends of the chain of the moose. $S$ vanishes when a link in the moose chain is cut. As a consequence one has to introduce a dynamical non local field connecting the two ends of the moose. Then the model acquires an additional custodial symmetry which protects this result. We examine also the possibility of a strong suppression of $S$ through an exponential behavior of the link couplings as suggested by Randall Sundrum metric.

  15. Interfacial coarsening dynamics in epitaxial growth with slope selection

    Science.gov (United States)

    Moldovan; Golubovic

    2000-06-01

    We investigate interfacial dynamics of molecular-beam epitaxy (MBE) growth in the presence of instabilities inducing formation of pyramids. We introduce a kinetic scaling theory which provides an analytic understanding of the coarsening dynamics laws observed in numerous experiments and simulations of the MBE. We address MBE growth on crystalline surfaces with different symmetries in order to explain experimentally observed differences between the growth on (111) and (001) surfaces and understand the coarsening exponents measured on these surfaces. We supplement our kinetic scaling theory by numerical simulations which document that the edges of the pyramids, forming a network across the growing interface, are essential for qualitative understanding of the coarsening dynamics of molecular-beam epitaxy.

  16. Using Heavy Clique Base Coarsening to Enhance Virtual Network Embedding

    Directory of Open Access Journals (Sweden)

    Ashraf A. Shahin

    2015-01-01

    Full Text Available Network virtualization allows cloud infrastructure providers to accommodate multiple virtual networks on a single physical network. However, mapping multiple virtual network resources to physical network components, called virtual network embedding (VNE, is known to be non-deterministic polynomial-time hard (NP-hard. Effective virtual network embedding increases the revenue by increasing the number of accepted virtual networks. In this paper, we propose virtual network embedding algorithm, which improves virtual network embedding by coarsening virtual networks. Heavy Clique matching technique is used to coarsen virtual networks. Then, the coarsened virtual networks are enhanced by using a refined Kernighan-Lin algorithm. The performance of the proposed algorithm is evaluated and compared with existing algorithms using extensive simulations, which show that the proposed algorithm improves virtual network embedding by increasing the acceptance ratio and the revenue.

  17. Modeling and simulation for phase coarsening: A comparison with experiment

    Science.gov (United States)

    Wang, K. G.; Glicksman, M. E.; Rajan, K.

    2004-06-01

    The phase coarsening of precipitates is modeled in the framework of Debye-Hückel theory. The interactions observed among a population of precipitates dispersed throughout a matrix can be described by diffusion screening. The relationship between the maximum particle radius and the volume fraction of the phases is established, and the rate of coarsening is related to the volume fraction and the self-similar particle size distribution. We simulated the dynamics of late-stage phase separation using multiparticle diffusion methods. Experimental measurements on the rates of coarsening of δ' ( Al3 Li) precipitates in binary Al-Li alloys are compared with our results using modeling and simulation. The theoretically predicted particle size distributions and the maximum radius expected for particles in the microstructure agree well with recent experimental results.

  18. A novel coarsening mechanism of droplets in immiscible fluid mixtures.

    Science.gov (United States)

    Shimizu, Ryotaro; Tanaka, Hajime

    2015-06-16

    In our daily lives, after shaking a salad dressing, we see the coarsening of oil droplets suspended in vinegar. Such a demixing process is observed everywhere in nature and also of technological importance. For a case of high droplet density, domain coarsening proceeds with inter-droplet collisions and the resulting coalescence. This phenomenon has been explained primarily by the so-called Brownian-coagulation mechanism: stochastic thermal forces exerted by molecules induce random motion of individual droplets, causing accidental collisions and subsequent interface-tension-driven coalescence. Contrary to this, here we demonstrate that the droplet motion is not random, but hydrodynamically driven by the composition Marangoni force due to an interfacial tension gradient produced in each droplet as a consequence of composition correlation among droplets. This alters our physical understanding of droplet coarsening in immiscible liquid mixtures on a fundamental level.

  19. Maps with vanishing denominator and their applications

    OpenAIRE

    Nicolò Pecora; Fabio Tramontana

    2016-01-01

    We survey the theoretical findings and a set of applications in several different fields concerning two-dimensional maps characterized by a vanishing denominator. This family of maps, and the related dynamic properties, were originally brought to the attention of the researchers through their appearance in an economic application. Nowadays such maps have also been used in other research areas such as ecology or biology confirming a broader application of the theoretical results about plane m...

  20. Geometrically frustrated coarsening dynamics in spinor Bose-Fermi mixtures

    Science.gov (United States)

    Phuc, Nguyen Thanh; Momoi, Tsutomu; Furukawa, Shunsuke; Kawaguchi, Yuki; Fukuhara, Takeshi; Ueda, Masahito

    2017-01-01

    Coarsening dynamics theory describes equilibration of a broad class of systems. By studying the relaxation of a periodic array of microcondensates immersed in a Fermi gas, which mediates long-range spin interactions to simulate frustrated classical magnets, we show that coarsening dynamics can be suppressed by geometrical frustration. The system is found to eventually approach a metastable state which is robust against random field noise and characterized by finite correlation lengths together with the emergence of topologically stable Z2 vortices. We find universal scaling laws with no thermal-equilibrium analog that relate the correlation lengths and the number of vortices to the degree of frustration in the system.

  1. Coarsening dynamics in condensing zero-range processes and size-biased birth death chains

    Science.gov (United States)

    Jatuviriyapornchai, Watthanan; Grosskinsky, Stefan

    2016-05-01

    Zero-range processes with decreasing jump rates are well known to exhibit a condensation transition under certain conditions on the jump rates, and the dynamics of this transition continues to be a subject of current research interest. Starting from homogeneous initial conditions, the time evolution of the condensed phase exhibits an interesting coarsening phenomenon of mass transport between cluster sites characterized by a power law. We revisit the approach in Godrèche (2003 J. Phys. A: Math. Gen. 36 6313) to derive effective single site dynamics which form a nonlinear birth death chain describing the coarsening behavior. We extend these results to a larger class of parameter values, and introduce a size-biased version of the single site process, which provides an effective tool to analyze the dynamics of the condensed phase without finite size effects and is the main novelty of this paper. Our results are based on a few heuristic assumptions and exact computations, and are corroborated by detailed simulation data.

  2. A remark on Kov\\'acs' vanishing theorem

    CERN Document Server

    Fujino, Osamu

    2012-01-01

    We give an alternative proof of Kov\\'acs' vanishing theorem. Our proof is based on the standard arguments of the minimal model theory. We do not need the notion of Du Bois pairs. We reduce Kov\\'acs' vanishing theorem to the well-known relative Kawamata--Viehweg--Nadel vanishing theorem.

  3. Precipitate coarsening and self organization in erbium-doped silica

    DEFF Research Database (Denmark)

    Sckerl, Mads W.; Guldberg-Kjær, Søren Andreas; Poulsen, Mogens Rysholt

    1999-01-01

    , and formation of erbium-rich. precipitates is seen to occur if the erbium concentration exceeds similar to 0.01 at. %. These precipitates are observed to coarsen and subsequently dissolve with increasing annealing time. Moreover, self organization of precipitates has been observed in the form of layering...

  4. The Vanishing Twin Syndrome: Two Cases of Extreme Malformations Associated With Vanished Twins.

    Science.gov (United States)

    Shinnick, Julia K; Khoshnam, Nasim; Archer, Sydney R; Quigley, Philip C; Robinson, Haynes; Keene, Sarah; Santore, Matthew T; Hill, Sarah; Patel, Binita; Shehata, Bahig M

    2017-01-01

    Two cases of devastating fetal malformations associated with vanished monochorionic twins were identified upon review of pathology files. A 35-year-old G1P0 woman and 36-year-old G3P1 woman were both diagnosed with an intrauterine twin gestation via transvaginal ultrasound at 10 weeks. The spectrum of fetal anomalies ranged from omphalocele, bilateral upper extremity, and unilateral lower extremity hypoplasia, to craniofacial malformation with diaphragmatic hernia. On histopathologic examination, the placentas demonstrated vascular anastomoses between the surviving co-twin and the "vanished" fetal sac. We propose anastomotic placental vasculature as a contributing factor to the observed fetal malformations. Additionally, genetic or teratogenic factors may have been attributed to the demise of the first twin and the anomalies seen in the other twin. While such instances are rare, they are important to consider when counseling patients regarding outcomes associated with a monochorionic vanished twin.

  5. Vanishing magnetic interactions in ferromagnetic thin films.

    Science.gov (United States)

    Dunn, J Hunter; Karis, O; Andersson, C; Arvanitis, D; Carr, R; Abrikosov, I A; Sanyal, B; Bergqvist, L; Eriksson, O

    2005-06-03

    We have used element-specific hysteresis measurements, based on the x-ray magnetic circular dichroism technique, to investigate magnetic trilayer structures composed of Fe and Ni layers. Within a critical regime we have discovered a class of structures in which the exchange interaction, the mechanism responsible for the macroscopic magnetism, can become vanishingly small. The experimental observations are supported by first principles theory and are explained as arising from a cancellation of several competing magnetic interactions. Hence, we have discovered a system with a novel exchange interaction between magnetic layers in direct contact that replaces the conventional exchange interaction in ferromagnets.

  6. Pattern Coarsening in a Two Dimensional Hexagonal System

    Science.gov (United States)

    Chaikin, Paul

    2008-03-01

    We have been studying the ordering, annealing, coarsening and alignment of two dimensional periodically ordered structures in thin films of diblock copolymers*. Coarsening by dislocation and disclination annihilation is clearly observed in AFM studies of monolayer films of cylindrical patterns with a time dependence given by t^α, with α about 1/4. However in hexagonal structures the mechanism is less well defined and appears to involve the collapse of small grains entrained in the grain boundaries of larger domains. Remarkably the exponent of α about 1/4 remains. We also report on shear aligned samples and samples quenched in a gradient after alignment. * Harrison C, Angelescu DE, Trawick M, Cheng ZD, Huse DA, Chaikin PM, Vega DA, Sebastian JM, Register RA, Adamson DH, EUROPHYSICS LETTERS 67 800-806 (2004)

  7. Numerical study of domain coarsening in anisotropic stripe patterns.

    Science.gov (United States)

    Boyer, Denis

    2004-06-01

    We study the coarsening of two-dimensional smectic polycrystals characterized by grains of oblique stripes with only two possible orientations. For this purpose, an anisotropic Swift-Hohenberg equation is solved. For quenches close enough to the onset of stripe formation, the average domain size increases with time as t(1/2). Further from onset, anisotropic pinning forces similar to Peierls stresses in solid crystals slow down defects, and growth becomes anisotropic. In a wide range of quench depths, dislocation arrays remain mobile and dislocation density roughly decays as t(-1/3), while chevron boundaries are totally pinned. We discuss some agreements and disagreements found with recent experimental results on the coarsening of anisotropic electroconvection patterns.

  8. Bubble motion measurements during foam drainage and coarsening.

    Science.gov (United States)

    Maurdev, G; Saint-Jalmes, A; Langevin, D

    2006-08-15

    We have studied bubble motion within a column of foam allowed to undergo free drainage. We have measured bubble motion upward with time and as a function of their initial positions. Depending on the gas used, which sets the coarsening and drainage rates, different bubble upward motion types have been identified (constant speed, acceleration or deceleration) and explained in relation with liquid downward flows. The proofs of the consistency between bubble upward motion and liquid downward flow are obtained both by comparing the bubble motion curves to the liquid drainage ones, and by comparing the time variations of the liquid fraction extracted from bubble motion to direct liquid fraction measurements by electrical conductimetry. The agreement between bubble position tracking and electrical conductivity shows in particular that it is possible to determine the drainage regime from such simple bubble motion measurements. This work also allowed us to demonstrate a special case of foam coarsening and expansion, occurring when the foam gas is less soluble than the outside one, caused by diffusion of this external gas into the foam. All these results allow us to build a picture of drainage and coarsening seen from the bubble point of view.

  9. Coulomb sink effect on coarsening of metal nanostructures on surfaces

    Institute of Scientific and Technical Information of China (English)

    Yong HAN; Feng LIU

    2008-01-01

    We discuss Coulomb effects on the coarsening of metal nanostructures on surfaces. We have proposed a new concept of a "Coulomb sink" [Phys. Rev. Lett., 2004, 93: 106102] to elucidate the effect of Coulomb charging on the coarsening of metal mesas grown on semiconductor surfaces. A charged mesa, due to its reduced chemical potential, acts as a Coulomb sink and grows at the expense of neighboring neu-tral mesas. The Coulomb sink provides a potentially useful method for the controlled fabrication of metal nanostructures. In this article, we will describe in detail the proposed physical models, which can explain qualitatively the most salient fea-tures of coarsening of charged Pb mesas on the Si(111) sur-face, as observed by scanning tunneling microscopy (STM). We will also describe a method of precisely fabricating large-scale nanocrystals with well-defined shape and size. By using the Coulomb sink effect, the artificial center-full-hol-lowed or half-hollowed nanowells can be created.

  10. Evolution of Local Microstructures (ELMS): Spatial Instabilities of Coarsening

    Science.gov (United States)

    Glicksman, Martin E.; Frazier, Donald O.; Rogers, Jan R.; Witherow, William K.; Downey, J. Patton; Facemire, Barbara R.

    1999-01-01

    This work examines the diffusional growth of discrete phase particles dispersed within a matrix. Engineering materials are microstructurally heterogeneous, and the details of the microstructure determine how well that material performs in a given application. Critical to the development of designing multiphase microstructures with long-term stability is the process of Ostwald ripening. Ripening, or phase coarsening, is a diffusion-limited process which arises in polydisperse multiphase materials. Growth and dissolution occur because fluxes of solute, driven by chemical potential gradients at the interfaces of the dispersed phase material, depend on particle size. The kinetics of these processes are "competitive," dictating that larger particles grow at the expense of smaller ones, overall leading to an increase of the average particle size. The classical treatment of phase coarsening was done by Todes, Lifshitz, and Slyozov, (TLS) in the limit of zero volume fraction, V(sub v), of the dispersed phase. Since the publication of TLS theory there have been numerous investigations, many of which sought to describe the kinetic scaling behavior over a range of volume fractions. Some studies in the literature report that the relative increase in coarsening rate at low (but not zero) volume fractions compared to that / 2 1/ 3 predicted by TLS is proportional to V(sub v)(exp 1/2), whereas others suggest V(sub v)(exp 1/3). This issue has been resolved recently by simulation studies at low volume fractions in three dimensions by members of the Rensselaer/MSFC team.

  11. Coarsening kinetics of topologically highly correlated grain boundary networks

    Science.gov (United States)

    Tang, Ming; Reed, Bryan W.; Kumar, Mukul

    2012-08-01

    We apply phase-field simulations in two dimensions to study the thermal coarsening of grain boundary (GB) networks with high fractions of twin and twin-variant boundaries, which for example are seen in grain-boundary-engineered FCC materials. Two types of grain boundary networks with similar starting special boundary fractions but different topological features were considered as initial conditions for the grain growth simulations. A lattice Monte Carlo method creates polycrystalline microstructures (Reed and Kumar (RK)), which exhibit hierarchical organization of random and special coincidence site lattice boundaries. The other type of microstructures (randomly distributed (RD)) contains random distributions of special boundaries subject only to crystallographic constraints. Under the assumption that random boundaries have larger energy and much higher mobility than special boundaries, simulations show that increasing the initial special boundary fraction in both microstructures slows down grain growth. However, the two starting microstructures exhibit very different behavior in the evolution of GB character and triple junction (TJ) distributions. The RD networks coarsened more slowly than the RK networks with comparable initial fractions of special boundaries. The observed trend in the evolution of the RK microstructures is explained by an extended von Neumann-Mullins analysis. This study demonstrates that the special boundary fraction is not a sufficient indicator of the coarsening behavior of twinned GB networks; the network topology must also be considered to correctly predict the grain growth kinetics.

  12. Capillary dynamics of drops and bubbles: Splashing, wetting, electrocoalescence, inverse coarsening, and thin films

    Science.gov (United States)

    Bird, James Chandler

    Small drops and the thin-films of bubbles are similar in that the surface to volume ratio is large. Consequently, capillary forces, which result from changes in the surface energy, tend to dominate the drop and bubble dynamics. For example, capillarity is responsible for breaking up a liquid jet from a faucet in a sink into a stream of individual droplets, and for coalescing these droplets into a puddle at the bottom of the sink. This dissertation identifies four situations in which a drop or a bubble exhibits unusual and perhaps counter-intuitive dynamics. The first example (Chapter 2) occurs when a drop impacts either an angled or moving dry, solid surface. Existing physical models attempt to predict the resulting dynamics, spreading or splashing, based on a variety of parameters. Yet it is unclear how these models would extend to include tangential velocity. Our high-speed experiments highlight a distinct third regime in which a fraction of the drop spreads while the other part splashes. The second example (Chapter 3) occurs when a drop contacts a wettable surface with a finite contact angle. Our high-speed experiments challenge the existing models by both showing that the spreading is inertially dominated and that the distance spread follows a power-law scaling in time where the exponent depends on the equilibrium contact angle. The third example (Chapter 4) occurs when two drops are drawn together in an electric field. When the voltage between the drops is low, the drops contact and coalesce. However, when the voltage is sufficiently high, the drops contact and then recoil. The fourth example (Chapter 5) occurs when a bubble on a liquid or solid surface ruptures. Foam coarsening theory would predict that the bubble vanishes when it pops, yet our experiments show that a ring of smaller bubbles is created from the retracting film. This inverse coarsening phenomena is a source of aerosols, and therefore may have implications for health and climate. This

  13. Vanishing "tattoo" multisensor for biomedical diagnostics

    Science.gov (United States)

    Moczko, E.; Meglinski, I.; Piletsky, S.

    2008-02-01

    Currently, precise non-invasive diagnostics systems for the real-time multi detection and monitoring of physiological parameters and chemical analytes in the human body are urgently required by clinicians, physiologists and bio-medical researchers. We have developed a novel cost effective smart 'vanishing tattoo' (similar to temporary child's tattoos) consisting of environmental-sensitive dyes. Painlessly impregnated into the skin the smart tattoo is capable of generating optical/fluorescence changes (absorbance, transmission, reflectance, emission and/or luminescence within UV, VIS or NIR regions) in response to physical or chemical changes. These changes allow the identification of colour pattern changes similar to bar-code scanning. Such a system allows an easy, cheap and robust comprehensive detection of various parameters and analytes in a small volume of sample (e.g. variations in pH, temperature, ionic strength, solvent polarity, presence of redox species, surfactants, oxygen). These smart tattoos have possible applications in monitoring the progress of disease and transcutaneous drug delivery. The potential of this highly innovative diagnostic tool is wide and diverse and can impact on routine clinical diagnostics, general therapeutic management, skin care and cosmetic products testing as well as fundamental physiological investigations.

  14. Revisiting the vanishing refuge model of diversification.

    Science.gov (United States)

    Damasceno, Roberta; Strangas, Maria L; Carnaval, Ana C; Rodrigues, Miguel T; Moritz, Craig

    2014-01-01

    Much of the debate around speciation and historical biogeography has focused on the role of stabilizing selection on the physiological (abiotic) niche, emphasizing how isolation and vicariance, when associated with niche conservatism, may drive tropical speciation. Yet, recent re-emphasis on the ecological dimensions of speciation points to a more prominent role of divergent selection in driving genetic, phenotypic, and niche divergence. The vanishing refuge model (VRM), first described by Vanzolini and Williams (1981), describes a process of diversification through climate-driven habitat fragmentation and exposure to new environments, integrating both vicariance and divergent selection. This model suggests that dynamic climates and peripheral isolates can lead to genetic and functional (i.e., ecological and phenotypic) diversity, resulting in sister taxa that occupy contrasting habitats with abutting distributions. Here, we provide predictions for populations undergoing divergence according to the VRM that encompass habitat dynamics, phylogeography, and phenotypic differentiation across populations. Such integrative analyses can, in principle, differentiate the operation of the VRM from other speciation models. We applied these principles to a lizard species, Coleodactylus meridionalis, which was used to illustrate the model in the original paper. We incorporate data on inferred historic habitat dynamics, phylogeography and thermal physiology to test for divergence between coastal and inland populations in the Atlantic Forest of Brazil. Environmental and genetic analyses are concordant with divergence through the VRM, yet physiological data are not. We emphasize the importance of multidisciplinary approaches to test this and alternative speciation models while seeking to explain the extraordinarily high genetic and phenotypic diversity of tropical biomes.

  15. Downslope coarsening in aeolian grainflows of the Navajo Sandstone

    Science.gov (United States)

    Loope, David B.; Elder, James F.; Sweeney, Mark R.

    2012-07-01

    Downslope coarsening in grainflows has been observed on present-day dunes and generated in labs, but few previous studies have examined vertical sorting in ancient aeolian grainflows. We studied the grainflow strata of the Jurassic Navajo Sandstone in the southern Utah portion of its outcrop belt from Zion National Park (west) to Coyote Buttes and The Dive (east). At each study site, thick sets of grainflow-dominated cross-strata that were deposited by large transverse dunes comprise the bulk of the Navajo Sandstone. We studied three stratigraphic columns, one per site, composed almost exclusively of aeolian cross-strata. For each column, samples were obtained from one grainflow stratum in each consecutive set of the column, for a total of 139 samples from thirty-two sets of cross-strata. To investigate grading perpendicular to bedding within individual grainflows, we collected fourteen samples from four superimposed grainflow strata at The Dive. Samples were analyzed with a Malvern Mastersizer 2000 laser diffraction particle analyser. The median grain size of grainflow samples ranges from fine sand (164 μm) to coarse sand (617 μm). Using Folk and Ward criteria, samples are well-sorted to moderately-well-sorted. All but one of the twenty-eight sets showed at least slight downslope coarsening, but in general, downslope coarsening was not as well-developed or as consistent as that reported in laboratory subaqueous grainflows. Because coarse sand should be quickly sequestered within preserved cross-strata when bedforms climb, grain-size studies may help to test hypotheses for the stacking of sets of cross-strata.

  16. Faster GPU-based convolutional gridding via thread coarsening

    CERN Document Server

    Merry, Bruce

    2016-01-01

    Convolutional gridding is a processor-intensive step in interferometric imaging. While it is possible to use graphics processing units (GPUs) to accelerate this operation, existing methods use only a fraction of the available flops. We apply thread coarsening to improve the efficiency of an existing algorithm, and observe performance gains of up to $3.2\\times$ for single-polarization gridding and $1.9\\times$ for quad-polarization gridding on a GeForce GTX 980, and smaller but still significant gains on a Radeon R9 290X.

  17. Evolution of Local Microstructures: Spatial Instabilities of Coarsening Clusters

    Science.gov (United States)

    Frazier, Donald O.

    1999-01-01

    This work examines the diffusional growth of discrete phase particles dispersed within a matrix. Engineering materials are microstructurally heterogeneous, and the details of the microstructure determine how well that material performs in a given application. Critical to the development of designing multiphase microstructures with long-term stability is the process of Ostwald ripening. Ripening, or phase coarsening, is a diffusion-limited process which arises in polydisperse multiphase materials. Growth and dissolution occur because fluxes of solute, driven by chemical potential gradients at the interfaces of the dispersed phase material, depend on particle size. The kinetics of these processes are "competitive," dictating that larger particles grow at the expense of smaller ones, overall leading to an increase of the average particle size. The classical treatment of phase coarsening was done by Todes, Lifshitz, and Slyozov, (TLS) in the limit of zero volume fraction, V(sub v), of the dispersed phase. Since the publication of TLS theory there have been numerous investigations, many of which sought to describe the kinetic scaling behavior over a 0 range of volume fractions. Some studies in the literature report that the relative increase in coarsening rate at low (but not zero) volume fractions compared to that predicted by TLS is proportional to v(sub v)(exp 1/2), whereas others suggcest V(sub v)(exp 1/3). This issue has been resolved recently by simulation studies at low volume fractions in three dimensions by members of the Rensselaer/MSFC team. Our studies of ripening behavior using large-scale numerical simulations suggest that although there are different circumstances which can lead to either scaling law, the most important length scale at low volume fractions is the diffusional analog of the Debye screening length. The numerical simulations we employed exploit the use of a recently developed "snapshot" technique, and identifies the nature of the coarsening

  18. Graph Coarsening for Path Finding in Cybersecurity Graphs

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, Emilie A.; Johnson, John R.; Halappanavar, Mahantesh

    2013-01-01

    n the pass-the-hash attack, hackers repeatedly steal password hashes and move through a computer network with the goal of reaching a computer with high level administrative privileges. In this paper we apply graph coarsening in network graphs for the purpose of detecting hackers using this attack or assessing the risk level of the network's current state. We repeatedly take graph minors, which preserve the existence of paths in the graph, and take powers of the adjacency matrix to count the paths. This allows us to detect the existence of paths as well as find paths that have high risk of being used by adversaries.

  19. Faster GPU-based convolutional gridding via thread coarsening

    Science.gov (United States)

    Merry, B.

    2016-07-01

    Convolutional gridding is a processor-intensive step in interferometric imaging. While it is possible to use graphics processing units (GPUs) to accelerate this operation, existing methods use only a fraction of the available flops. We apply thread coarsening to improve the efficiency of an existing algorithm, and observe performance gains of up to 3.2 × for single-polarization gridding and 1.9 × for quad-polarization gridding on a GeForce GTX 980, and smaller but still significant gains on a Radeon R9 290X.

  20. Observations of microstructural coarsening in micro flip-chip solder joints

    Science.gov (United States)

    Barney, Monica M.; Morris, J. W.

    2001-09-01

    Coarsening of solder microstructures dramatically affects fatigue lifetimes. This paper presents a study of microstructural evolution due to thermal cycling and aging of small solder joints. The lead-tin solder joints in this study have a height of 55 5 m and a tin content of 65 70 wt.%, with a degenerate eutectic microstructure. The joint microstructure coarsens more rapidly during aging at 160°C than cycling from 0 160°C. No coarsened bands are observed. The cycling data scales with standard coarsening equations, while the aging data fits to an enhanced trend. The joints experiencing 2.8% strain during cycling fail by 1000 cycles.

  1. Coarsening of firefighting foams containing fluorinated hydrocarbon surfactants

    Science.gov (United States)

    Kennedy, Matthew J.; Dougherty, John A.; Otto, Nicholas; Conroy, Michael W.; Williams, Bradley A.; Ananth, Ramagopal; Fleming, James W.

    2013-03-01

    Diffusion of gas between bubbles in foam causes growth of large bubbles at the expense of small bubbles and leads to increasing mean bubble size with time thereby affecting drainage. Experimental data shows that the effective diffusivity of nitrogen gas in aqueous film forming foam (AFFF), which is widely used in firefighting against burning liquids, is several times smaller than in 1% sodium dodecyl sulfate (SDS) foam based on time-series photographs of bubble size and weighing scale recordings of liquid drainage. Differences in foam structure arising from foam production might contribute to the apparent difference in the rates of coarsening. AFFF solution produces wetter foam with initially smaller bubbles than SDS solution due in part to the lower gas-liquid surface tension provided by the fluorosurfactants present in AFFF. Present method of foam production generates microbubble foam by high-speed co-injection of surfactant solution and gas into a tube of 3-mm diameter. These results contribute to our growing understanding of the coupling between foam liquid fraction, bubble size, surfactant chemistry, and coarsening. NRC Resident Research Associate at NRL

  2. A Mean-Field Theory for Coarsening Faceted Surfaces

    CERN Document Server

    Norris, Scott A

    2009-01-01

    A mean-field theory is developed for the scale-invariant length distributions observed during the coarsening of one-dimensional faceted surfaces. This theory closely follows the Lifshitz-Slyozov-Wagner theory of Ostwald ripening in two-phase systems [1-3], but the mechanism of coarsening in faceted surfaces requires the addition of convolution terms recalling the work of Smoluchowski [4] and Schumann [5] on coalescence. The model is solved by the exponential distribution, but agreement with experiment is limited by the assumption that neighboring facet lengths are uncorrelated. However, the method concisely describes the essential processes operating in the scaling state, illuminates a clear path for future refinement, and offers a framework for the investigation of faceted surfaces evolving under arbitrary dynamics. [1] I. Lifshitz, V. Slezov, Soviet Physics JETP 38 (1959) 331-339. [2] I. Lifshitz, V. Slyozov, J. Phys. Chem. Solids 19 (1961) 35-50. [3] C. Wagner, Elektrochemie 65 (1961) 581-591. [4] M. von S...

  3. General coarsened measurement references for revelation of a classical world

    Science.gov (United States)

    Xie, Dong; Xu, Chunling; Wang, Anmin

    2016-11-01

    It has been found that for a fixed degree of fuzziness in the coarsened references of measurements, the quantum-to-classical transition can be observed independent of the macroscopicity of the quantum state. We explore a general situation that the degree of fuzziness can change with the rotation angle between two states (different rotation angles represent different references). The fuzziness of reference comes from two kinds of fuzziness: the Hamiltonian (rotation frequency) and the timing (rotation time). For the fuzziness of the Hamiltonian alone, the degree of fuzziness for the reference will change with the rotation angle between two states, and the quantum effects can still be observed with any degree of fuzziness of Hamiltonian. For the fuzziness of timing, the degree of the coarsening reference is unchanged with the rotation angle. During the rotation of the measurement axis, the decoherence environment can also help the classical-to-quantum transition due to changing the direction of the measurement axis. Project supported by the National Natural Science Foundation of China (Grant No. 11375168).

  4. Vacum Black Hole Mass Formula Is a Vanishing Noether Charge

    Institute of Scientific and Technical Information of China (English)

    WUXiao-Ning; HUANGChao-Guang; 等

    2002-01-01

    The Noether current and its variation relation with respect to diffeomorphism invariance of gravitational theories have been derived from the horizontal variation and vertical-horizontal bi-variation of the Lagrangian,respectively.For Einstein's GR in the stationary,axisymmetric black holes,the mass formula in vacuum can be derived from this Noether current although it definitely vanishes.This indicates that the mass formula of black holes is a vanishing Noether charge in this case.The first law of black hole thermodynamics can also be derived from the variation relation of this vanishing Noether current.

  5. Vacuum Black Hole Mass Formula Is a Vanishing Noether Charge

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-Ning; GUO Han-Ying; HUANG Chao-Guang; WU Ke

    2002-01-01

    The Noether current and its variation relation with respect to diffeomorphism invariance of gravitationaltheories have been derived from the horizontal variation and vertical-horizontal bi-variation of the Lagrangian, respec-tively. For Einstein's GR in the stationary, axisymmetric black holes, the mass formula in vacuum can be derived fromthis Noether current although it definitely vanishes. This indicates that the mass formula of black holes is a vanishingNoether charge in this case. The first law of black hole thermodynamics can also be derived from the variation relationof this vanishing Noether current.

  6. Adiabatic limits,vanishing theorems and the noncommutative residue

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    In this paper,we compute the adiabatic limit of the scalar curvature and prove several vanishing theorems by taking adiabatic limits.As an application,we give a Kastler-Kalau-Walze type theorem for foliations.

  7. Lubricated wrinkles: imposed constraints affect the dynamics of wrinkle coarsening

    CERN Document Server

    Kodio, Ousmane; Vella, Dominic

    2016-01-01

    We study the dynamic coarsening of wrinkles in an elastic sheet that is compressed while lying on a thin layer of viscous liquid. When the ends of the sheet are instantaneously brought together by a small distance, viscous resistance initially prevents the sheet from adopting a globally buckled shape. Instead, the sheet accommodates the compression by wrinkling. Previous scaling arguments suggested that a balance between the sheet's bending stiffness and viscous effects lead to a wrinkle wavelength $\\lambda$ that increases with time $t$ according to $\\lambda\\propto t^{1/6}$. We show that taking proper account of the compression constraint leads to a logarithmic correction of this result, $\\lambda\\propto (t/\\log t)^{1/6}$. This correction is significant over experimentally observable time spans, and leads us to reassess previously published experimental data.

  8. Lubricated wrinkles: Imposed constraints affect the dynamics of wrinkle coarsening

    Science.gov (United States)

    Kodio, Ousmane; Griffiths, Ian M.; Vella, Dominic

    2017-01-01

    We study the dynamic coarsening of wrinkles in an elastic sheet that is compressed while lying on a thin layer of viscous liquid. When the ends of the sheet are instantaneously brought together by a small distance, viscous resistance initially prevents the sheet from adopting a globally buckled shape. Instead, the sheet accommodates the compression by wrinkling. Previous scaling arguments suggested that a balance between the sheet's bending stiffness and viscous effects lead to a wrinkle wavelength λ that increases with time t according to λ ∝t1 /6 . We show that taking proper account of the compression constraint leads to a logarithmic correction of this result, λ ∝(t/logt ) 1 /6 . This correction is significant over experimentally observable time spans and leads us to reassess previously published experimental data.

  9. Processes of microstructure coarsening at liquid phase sintering.

    Science.gov (United States)

    Anestiev, L; Froyen, L

    2000-06-01

    A different approach to the theoretical description of the classical theory of Ostwald ripening at liquid phase sintering has been proposed. The model developed in the present approach is based on an equation describing the growth kinetics of the particles, which is different from those used until now. The model developed here accounts automatically for the influence of the initial volume fraction and predicts correctly: the time dependence of rho; at t-->infinity-rho;(3)(t)-rho;(3)(0)=Kt; the form of the distribution function after considerable coarsening time; the experimentally observed values for the relation rho(max)/rho;; and the phenomena of "abnormal growth" at liquid phase sintering.

  10. Geometrical properties of the Potts model during the coarsening regime.

    Science.gov (United States)

    Loureiro, Marcos P O; Arenzon, Jeferson J; Cugliandolo, Leticia F

    2012-02-01

    We study the dynamic evolution of geometric structures in a polydegenerate system represented by a q-state Potts model with nonconserved order parameter that is quenched from its disordered into its ordered phase. The numerical results obtained with Monte Carlo simulations show a strong relation between the statistical properties of hull perimeters in the initial state and during coarsening: The statistics and morphology of the structures that are larger than the averaged ones are those of the initial state, while the ones of small structures are determined by the curvature-driven dynamic process. We link the hull properties to the ones of the areas they enclose. We analyze the linear von Neumann-Mullins law, both for individual domains and on the average, concluding that its validity, for the later case, is limited to domains with number of sides around 6, while presenting stronger violations in the former case. © 2012 American Physical Society

  11. Relaxation and coarsening of weakly-interacting breathers in a simplified DNLS chain

    Science.gov (United States)

    Iubini, Stefano; Politi, Antonio; Politi, Paolo

    2017-07-01

    The discrete nonlinear Schrödinger (DNLS) equation displays a parameter region characterized by the presence of localized excitations (breathers). While their formation is well understood and it is expected that the asymptotic configuration comprises a single breather on top of a background, it is not clear why the dynamics of a multi-breather configuration is essentially frozen. In order to investigate this question, we introduce simple stochastic models, characterized by suitable conservation laws. We focus on the role of the coupling strength between localized excitations and background. In the DNLS model, higher breathers interact more weakly, as a result of their faster rotation. In our stochastic models, the strength of the coupling is controlled directly by an amplitude-dependent parameter. In the case of a power-law decrease, the associated coarsening process undergoes a slowing down if the decay rate is larger than a critical value. In the case of an exponential decrease, a freezing effect is observed that is reminiscent of the scenario observed in the DNLS. This last regime arises spontaneously when direct energy diffusion between breathers and background is blocked below a certain threshold.

  12. A Novel Coarsening Method for Scalable and Efficient Mesh Generation

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, A; Hysom, D; Gunney, B

    2010-12-02

    In this paper, we propose a novel mesh coarsening method called brick coarsening method. The proposed method can be used in conjunction with any graph partitioners and scales to very large meshes. This method reduces problem space by decomposing the original mesh into fixed-size blocks of nodes called bricks, layered in a similar way to conventional brick laying, and then assigning each node of the original mesh to appropriate brick. Our experiments indicate that the proposed method scales to very large meshes while allowing simple RCB partitioner to produce higher-quality partitions with significantly less edge cuts. Our results further indicate that the proposed brick-coarsening method allows more complicated partitioners like PT-Scotch to scale to very large problem size while still maintaining good partitioning performance with relatively good edge-cut metric. Graph partitioning is an important problem that has many scientific and engineering applications in such areas as VLSI design, scientific computing, and resource management. Given a graph G = (V,E), where V is the set of vertices and E is the set of edges, (k-way) graph partitioning problem is to partition the vertices of the graph (V) into k disjoint groups such that each group contains roughly equal number of vertices and the number of edges connecting vertices in different groups is minimized. Graph partitioning plays a key role in large scientific computing, especially in mesh-based computations, as it is used as a tool to minimize the volume of communication and to ensure well-balanced load across computing nodes. The impact of graph partitioning on the reduction of communication can be easily seen, for example, in different iterative methods to solve a sparse system of linear equation. Here, a graph partitioning technique is applied to the matrix, which is basically a graph in which each edge is a non-zero entry in the matrix, to allocate groups of vertices to processors in such a way that many of

  13. Surface grain coarsening and surface softening during machining of ultra-fine grained titanium

    Directory of Open Access Journals (Sweden)

    Symonova A.A.

    2012-01-01

    Full Text Available Experiments are run to show that different machining conditions applied to ultra-fine grained pure titanium lead to different levels of grain coarsening and softening near the machined surface. Under “hard” machining conditions the upper 40 microns of the machined surface are altered with a decreased microhardness. The experimental results are reasonably reproduced by model calculations. Expanding the parameter field of the model calculations, the surface coarsening diagram and the surface softening diagram due to machining are presented, showing the region of technological parameters, under which neither grain coarsening nor softening takes place along the machined surface.

  14. Vanishing DC holographic conductivity from a magnetic monopole condensate

    CERN Document Server

    Rougemont, Romulo; Zarro, Carlos A D; Wotzasek, Clovis; Guimaraes, Marcelo S; Granado, Diego R

    2015-01-01

    We show how to obtain a vanishing DC conductivity in 3-dimensional strongly coupled QFT's using a massive 2-form field in the bulk that satisfies a special kind of boundary condition. The real and imaginary parts of the AC conductivity are evaluated in this holographic setup and we show that the DC conductivity identically vanishes even for an arbitrarily small (though nonzero) value of the 2-form mass in the bulk. We identify the bulk action of the massive 2-form with the low energy effective theory describing the long wavelength excitations of a magnetic monopole condensate in the bulk. Our results indicate that a condensate of magnetic monopoles in a 4-dimensional bulk lead to a vanishing DC holographic conductivity in 3-dimensional strongly coupled QFT's.

  15. Vanishing DC holographic conductivity from a magnetic monopole condensate

    Energy Technology Data Exchange (ETDEWEB)

    Rougemont, Romulo [Instituto de Física, Universidade de São Paulo,C.P. 66318, 05315-970, São Paulo, SP (Brazil); Noronha, Jorge [Instituto de Física, Universidade de São Paulo,C.P. 66318, 05315-970, São Paulo, SP (Brazil); Department of Physics, Columbia University,538 West 120th Street, New York, NY 10027 (United States); Zarro, Carlos A.D.; Wotzasek, Clovis [Instituto de Física, Universidade Federal do Rio de Janeiro,21941-972, Rio de Janeiro, RJ (Brazil); Guimaraes, Marcelo S. [Instituto de Física, Universidade do Estado do Rio de Janeiro,20550-013, Rio de Janeiro, RJ (Brazil); Granado, Diego R. [Instituto de Física, Universidade do Estado do Rio de Janeiro,20550-013, Rio de Janeiro, RJ (Brazil); Department of Physics and Astronomy, Ghent University, Krijgslaan 281-S9, 9000 Gent (Belgium)

    2015-07-14

    We show how to obtain a vanishing DC conductivity in 3-dimensional strongly coupled QFT’s using a massive 2-form field in the bulk that satisfies a special kind of boundary condition. The real and imaginary parts of the AC conductivity are evaluated in this holographic setup and we show that the DC conductivity identically vanishes even for an arbitrarily small (though nonzero) value of the 2-form mass in the bulk. We identify the bulk action of the massive 2-form with an effective theory describing a phase in which magnetic monopoles have condensed in the bulk. Our results indicate that a condensate of magnetic monopoles in a 4-dimensional bulk leads to a vanishing DC holographic conductivity in 3-dimensional strongly coupled QFT’s.

  16. Vanishing embryo syndrome’ in IVF/ICSI

    DEFF Research Database (Denmark)

    Hvidtjørn, Dorte; Grove, Jakob; Schendel, Diana

    2005-01-01

    BACKGROUND: In a Danish population-based cohort study assessing the risk of cerebral palsy in children bornafter IVF, we made some interesting observations regarding ‘vanishing co-embryos’. METHODS andRESULTS: All live-born children born in Denmark from 1 January 1995 to 31 December 2000 were...... found indications of an increasedrisk of cerebral palsy in those children resulting from pregnancies, where the number of embryos transferred washigher than the number of children born. CONCLUSIONS: The association between vanishing embryo syndromeand incidence of cerebral palsy following IVF requires...

  17. On the vanishing rate of smooth CR functions

    Directory of Open Access Journals (Sweden)

    Giuseppe Della Sala

    2014-01-01

    Full Text Available Let be a lineally convex hypersurface of ℂⁿ of finite type, 0∈. Then there exist non-trivial smooth CR functions on that are flat at 0, i.e. whose Taylor expansion about 0 vanishes identically. Our aim is to characterize the rate at which flat CR functions can decrease without vanishing identically. As it turns out, non-trivial CR functions cannot decay arbitrarily fast, and a possible way of expressing the critical rate is by comparison with a suitable exponential of the modulus of a local peak function.

  18. Convergence results for a coarsening model using global linearization

    CERN Document Server

    Gallay, T; Gallay, Th.

    2002-01-01

    We study a coarsening model describing the dynamics of interfaces in the one-dimensional Allen-Cahn equation. Given a partition of the real line into intervals of length greater than one, the model consists in constantly eliminating the shortest interval of the partition by merging it with its two neighbors. We show that the mean-field equation for the time-dependent distribution of interval lengths can be explicitly solved using a global linearization transformation. This allows us to derive rigorous results on the long-time asymptotics of the solutions. If the average length of the intervals is finite, we prove that all distributions approach a uniquely determined self-similar solution. We also obtain global stability results for the family of self-similar profiles which correspond to distributions with infinite expectation. eliminating the shortest interval of the partition by merging it with its two neighbors. We show that the mean-field equation for the time-dependent distribution of interval lengths can...

  19. Characterization of abnormal grain coarsening in Alloy 718

    Directory of Open Access Journals (Sweden)

    Watson Richard

    2014-01-01

    Full Text Available Even though the phenomenon of abnormal grain coarsening (AGC or “exploded grains” has been known to occur in Alloy 718 industrial forgings there is still no satisfactory explanation for it. For this reason, detailed microstructure analysis has been carried out in normal and abnormal regions. Electron Backscatter Diffraction (EBSD was employed to determine grain size, boundary distribution and measure stored energy, while backscattered imagining in a FEGSEM was used to measure δ precipitate size and morphology. It was found that abnormal regions show almost 3 times as many twin boundaries compared to a normal region. In addition, the δ phase morphologies differ very significantly when comparing these two different regions. Normal regions display δ phase with a plate like nature, whereas in abnormal regions, δ particles appear to be more spherical. Furthermore, there are clear indications of differences in δ volume fractions between the two regions. Whilst in normal regions the δ phase is found predominantly at grain boundaries, in abnormal regions the δ is also found within grains. Both backscatter images and EBSD scans indicate that there are higher levels of stored energy within the normal regions, compared to the abnormal regions. These observations suggest that AGC occurs in regions where dynamic recrystallization does not happen and where recrystallization during solution heat treatment is affected by the local particle distribution.

  20. Grain coarsening mechanism of Cu thin films by rapid annealing

    Energy Technology Data Exchange (ETDEWEB)

    Sasajima, Yasushi, E-mail: sasajima@mx.ibaraki.ac.jp; Kageyama, Junpei; Khoo, Khyoupin; Onuki, Jin

    2010-09-30

    Cu thin films have been produced by an electroplating method using nominal 9N anode and nominal 6N CuSO{sub 4}.5H{sub 2}O electrolyte. Film samples were heat-treated by two procedures: conventional isothermal annealing in hydrogen atmosphere (abbreviated as H{sub 2} annealing) and rapid thermal annealing with an infrared lamp (abbreviated as RTA). After heat treatment, the average grain diameters and the grain orientation distributions were examined by electron backscattering pattern analysis. The RTA samples (400 {sup o}C for 5 min) have a larger average grain diameter, more uniform grain distribution and higher ratio of (111) orientation than H{sub 2} annealed samples (400 {sup o}C for 30 min). This means that RTA can produce films with coarser and more uniformly distributed grains than H{sub 2} annealing within a short time, i.e. only a few minutes. To clarify the grain coarsening mechanism, grain growth by RTA was simulated using the phase field method. The simulated grain diameter reaches its maximum at a heating rate which is the same order as that in the actual RTA experiment. The maximum grain diameter is larger than that obtained by H{sub 2} annealing with the same annealing time at the isothermal stage as in RTA. The distribution of the misorientation was analyzed which led to a proposed grain growth model for the RTA method.

  1. In Situ Observation for Abnormal Grain Coarsening in Vacuum-Carburizing Process

    Science.gov (United States)

    Yogo, Yasuhiro; Tanaka, Kouji

    2014-06-01

    An in situ observation method was developed to investigate abnormal grain coarsening which occurs around the surface of steel during the vacuum-carburizing process. In this method, diffusion of carbon atoms in the vacuum carburizing was simulated by a cementite and steel diffusion couple. Abnormal grain coarsening, which appeared around the cementite and steel interface, was observed by a confocal scanning laser microscope. With this method, it was observed that when holding time was 60 seconds, the temperature at which the abnormal grain coarsening appeared in a specimen was higher when carburized than the temperature when not carburized. On the contrary, when holding time was 120 seconds, the temperature at which the abnormal grain coarsening appeared in a specimen was 10 K to 20 K lower than that in a non-carburized specimen. The validity of the observed results was confirmed by the calculated NbC fraction using Nb solubility and measured carbon content.

  2. Symmetry breaking and coarsening of clusters in a prototypical driven granular gas.

    Science.gov (United States)

    Livne, Eli; Meerson, Baruch; Sasorov, Pavel V

    2002-11-01

    Granular hydrodynamics predicts symmetry-breaking instability in a two-dimensional ensemble of nearly elastically colliding smooth hard disks driven, at zero gravity, by a rapidly vibrating sidewall. Supercritical and subcritical symmetry-breaking bifurcations of the stripe state are identified, and the supercritical bifurcation curve is computed. The cluster dynamics proceed as a coarsening process mediated by the gas phase. Well above the bifurcation point the final steady state, selected by coarsening, represents a single strongly localized densely packed "droplet."

  3. Type 1,1-operators defined by vanishing frequency modulation

    DEFF Research Database (Denmark)

    Johnsen, Jon

    2009-01-01

    This paper presents a general definition of pseudo-differential operators of type 1,1; the definition is shown to be the largest one that is both compatible with negliible operators and stable under vanishing frequency modulation. Elaborating counter-examples of Ching, Hörmander and Parenti...

  4. Consequences of vanishing twins in IVF/ICSI pregnancies

    DEFF Research Database (Denmark)

    Pinborg, Anja Bisgaard; Lidegaard, Ojvind; la Cour Freiesleben, Nina

    2005-01-01

    Spontaneous reductions are a possible cause of the increased morbidity in IVF singletons. The aim of this study was to assess incidence rates of spontaneous reductions in IVF/ICSI twin pregnancies and to compare short- and long-term morbidity in survivors of a vanishing co-twin with singletons...

  5. Type 1,1-operators defined by vanishing frequency modulation

    DEFF Research Database (Denmark)

    Johnsen, Jon

    This paper presents a general definition of pseudo-differential operators of type 1,1; the definition is shown to be the largest one that is both compatible with negligible operators and stable under vanishing frequency modulation. Elaborating counter-examples of Ching andHörmander, type 1...

  6. Vanishing non-local regularization of a scalar conservation law

    Directory of Open Access Journals (Sweden)

    Jerome Droniou

    2003-11-01

    Full Text Available We prove that the solution to the regularization of a scalar conservation law by a fractional power of the Laplacian converges, as the regularization vanishes, to the entropy solution of the hyperbolic problem. We also give an error estimate when the initial condition has bounded variation.

  7. Consequences of vanishing twins in IVF/ICSI pregnancies

    DEFF Research Database (Denmark)

    Pinborg, Anja Bisgaard; Lidegaard, Ojvind; la Cour Freiesleben, Nina;

    2005-01-01

    Spontaneous reductions are a possible cause of the increased morbidity in IVF singletons. The aim of this study was to assess incidence rates of spontaneous reductions in IVF/ICSI twin pregnancies and to compare short- and long-term morbidity in survivors of a vanishing co-twin with singletons...

  8. The Vanishing Tetrad Test: Another Test of Model Misspecification

    Science.gov (United States)

    Roos, J. Micah

    2014-01-01

    The Vanishing Tetrad Test (VTT) (Bollen, Lennox, & Dahly, 2009; Bollen & Ting, 2000; Hipp, Bauer, & Bollen, 2005) is an extension of the Confirmatory Tetrad Analysis (CTA) proposed by Bollen and Ting (Bollen & Ting, 1993). VTT is a powerful tool for detecting model misspecification and can be particularly useful in cases in which…

  9. Instability of the magnetohydrodynamics system at vanishing Reynolds number

    Science.gov (United States)

    Bouya, Ismaël

    2013-12-01

    The aim of this note is to study the dynamo properties of the magnetohydrodynamics system at vanishing R m . Improving the analysis in Gérard-Varet (SIAM J Math Anal 37(3):815-840, 2006), we shall establish a generic Lyapunov instability result.

  10. The Vanishing Tetrad Test: Another Test of Model Misspecification

    Science.gov (United States)

    Roos, J. Micah

    2014-01-01

    The Vanishing Tetrad Test (VTT) (Bollen, Lennox, & Dahly, 2009; Bollen & Ting, 2000; Hipp, Bauer, & Bollen, 2005) is an extension of the Confirmatory Tetrad Analysis (CTA) proposed by Bollen and Ting (Bollen & Ting, 1993). VTT is a powerful tool for detecting model misspecification and can be particularly useful in cases in which…

  11. A combinatorial method for the vanishing of the Poisson brackets of an integrable Lotka-Volterra system

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Yoshiaki [Institute of Statistical Mathematics and the Graduate University for Advanced Studies, 4-6-7 Minami-Azabu Minatoku, Tokyo 106-8569 (Japan)], E-mail: itoh@ism.ac.jp

    2009-01-16

    The combinatorial method is useful to obtain conserved quantities for some nonlinear integrable systems, as an alternative to the Lax representation method. Here we extend the combinatorial method and introduce an elementary geometry to show the vanishing of the Poisson brackets of the Hamiltonian structure for a Lotka-Volterra system of competing species. We associate a set of points on a circle with a set of species of the Lotka-Volterra system, where the dominance relations between points are given by the dominance relations between the species. We associate each term of the conserved quantities with a subset of points on the circle, which simplifies to show the vanishing of the Poisson brackets.

  12. Emergent Gravity from Vanishing Energy-Momentum Tensor

    CERN Document Server

    Carone, Christopher D; Vaman, Diana

    2016-01-01

    A constraint of vanishing energy-momentum tensor is motivated by a variety of perspectives on quantum gravity. We demonstrate in a concrete example how this constraint leads to a metric-independent theory in which quantum gravity emerges as a nonperturbative artifact of regularization-scale physics. We analyze a scalar theory similar to the Dirac-Born-Infeld (DBI) theory with vanishing gauge fields, with the DBI Lagrangian modulated by a scalar potential. In the limit of a large number of scalars, we explicitly demonstrate the existence of a composite massless spin-2 graviton in the spectrum that couples to matter as in Einstein gravity. We comment on the cosmological constant problem and the generalization to theories with fermions and gauge fields.

  13. Vanishing of dipole matrix elements at level crossings.

    Science.gov (United States)

    Kocher, C. A.

    1972-01-01

    Demonstration that the vanishing of certain coupling matrix elements at level crossings follow from angular momentum commutation relations. A magnetic dipole transition having delta M = plus or minus 1, induced near a crossing of the levels in a nonzero magnetic field, is found to have a dipole matrix element comparable to or smaller than the quotient of the level separation and the field. This result also applies in the analogous electric field electric dipole case.

  14. Compactification over coset spaces with torsion and vanishing cosmological constant

    Energy Technology Data Exchange (ETDEWEB)

    Batakis, N.A.; Farakos, K.; Koutsoumbas, G.; Zoupanos, G.; Kapetanakis, D.

    1989-04-13

    We consider the compactification of ten-dimensional Einstein-Yang-Mills theories over non-symmetric, six-dimensional homogeneous coset spaces with torsion. We examine the Einstein-Yang-Mills equations of motion requiring vanishing cosmological constant at ten and four dimensions and we present examples of compactifying solutions. It appears that the introduction of more than one radii in the coset space, when possible, may be mandatory for the existence of compactifying solutions.

  15. Near horizon structure of extremal vanishing horizon black holes

    Directory of Open Access Journals (Sweden)

    S. Sadeghian

    2015-11-01

    Full Text Available We study the near horizon structure of Extremal Vanishing Horizon (EVH black holes, extremal black holes with vanishing horizon area with a vanishing one-cycle on the horizon. We construct the most general near horizon EVH and near-EVH ansatz for the metric and other fields, like dilaton and gauge fields which may be present in the theory. We prove that (1 the near horizon EVH geometry for generic gravity theory in generic dimension has a three dimensional maximally symmetric subspace; (2 if the matter fields of the theory satisfy strong energy condition either this 3d part is AdS3, or the solution is a direct product of a locally 3d flat space and a d−3 dimensional part; (3 these results extend to the near horizon geometry of near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry. We present some specific near horizon EVH geometries in 3, 4 and 5 dimensions for which there is a classification. We also briefly discuss implications of these generic results for generic (gauged supergravity theories and also for the thermodynamics of near-EVH black holes and the EVH/CFT proposal.

  16. Three theorems on near horizon extremal vanishing horizon geometries

    Directory of Open Access Journals (Sweden)

    S. Sadeghian

    2016-02-01

    Full Text Available EVH black holes are Extremal black holes with Vanishing Horizon area, where vanishing of horizon area is a result of having a vanishing one-cycle on the horizon. We prove three theorems regarding near horizon geometry of EVH black hole solutions to generic Einstein gravity theories in diverse dimensions. These generic gravity theories are Einstein–Maxwell-dilaton-Λ theories, and gauged or ungauged supergravity theories with U(1 Maxwell fields. Our three theorems are: (1 The near horizon geometry of any EVH black hole has a three dimensional maximally symmetric subspace. (2 If the energy momentum tensor of the theory satisfies strong energy condition either this 3d part is an AdS3, or the solution is a direct product of a locally 3d flat space and a d−3 dimensional part. (3 These results extend to the near horizon geometry of near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry.

  17. Secondary Hardening, Austenite Grain Coarsening and Surface Decarburization Phenomenon in Nb-Bearing Spring Steel

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The secondary hardening, the austenite grain coarsening and the surface decarburization phenomenon of Nb-bearing spring steel were investigated, and the effects of niobium on tempered microstructure was studied using scanning electron microscope. The results show that the micro-addition of niobium increases the tempering resistance and produces secondary hardening. The effect of niobium on the size and distribution of cementite particles is one of the primary reasons to increase the hardness after tempering. The grain-coarsening temperature of the spring steel is raised 150 ~C due to Nb-addition. Furthermore, both the secondary hardening and the austenite grain coarsening phenomenon congruously demonstrate niobium begins observably dissolving above 1 100 ℃ in the spring steel. Be- sides, niobium microalloying is an effective and economy means to decrease the decarburization sensitivity of the spring steels.

  18. The discrete modified Korteweg-de Vries equation with non-vanishing boundary conditions: Interactions of solitons

    Energy Technology Data Exchange (ETDEWEB)

    Shek, E.C.M. [Department of Mechanical Engineering, University of Hong Kong, Pokfulam, Hong Kong (China); Chow, K.W. [Department of Mechanical Engineering, University of Hong Kong, Pokfulam, Hong Kong (China)], E-mail: kwchow@hkusua.hku.hk

    2008-04-15

    The discrete modified Korteweg-de Vries equation with negative cubic nonlinearity is considered for non-vanishing boundary condition in the far field. A Hirota bilinear form is established and expressions for 1- and 2-soliton are calculated. The amplitude of the soliton cannot exceed a maximum, and further increasing the wave number will just result in a solitary wave of larger width. This special class of solitary waves is termed 'plateau' solitons here. The interaction of a soliton of less than the maximum amplitude with such a 'plateau' soliton will result in a reversal of polarity of the smaller soliton during the interaction process.

  19. Direct observation of grain rotations during coarsening of a semisolid Al-Cu alloy

    DEFF Research Database (Denmark)

    Dake, Jules M.; Oddershede, Jette; Sørensen, Henning O.;

    2016-01-01

    -during which densification plays a subordinate role to coarsening-we have used 3D X-ray diffraction microscopy to track the changes in sample microstructure induced by annealing. The results establish the occurrence of significant particle rotations, driven in part by the dependence of boundary energy...... ideal arrangements of constituent powders while ignoring their underlying crystallinity, achieve at best a qualitative description of the rearrangement, densification, and coarsening of powder compacts during thermal processing. Treating a semisolid Al-Cu alloy as a model system for late-stage sintering...... on crystallographic misorientation. Evidently, a comprehensive model for sintering must incorporate crystallographic parameters into the thermodynamic driving forces governing microstructural evolution....

  20. Monitoring foam coarsening using a computer optical mouse as a dynamic laser speckle measurement sensor

    Indian Academy of Sciences (India)

    Jáder Guerrero; Enrique Mejia-Ospino; Rafael Cabanzo

    2013-12-01

    In this paper, we present an experimental approach to track coarsening process of foam using a computer optical mouse as a dynamic laser speckle measurement sensor. The dynamics of foam coarsening and rearrangement events cause changes in the intensity of laser speckle backscattered from the foam. A strong negative correlation between the average speed of the cursor and the evolution of bubble diameter was found. We used microscopic images to demonstrate that decrease in speed is related to increase in bubble size. The proposed set-up is not very expensive, is highly portable and can be used in laboratory measurements of dynamics in other kinds of opaque materials.

  1. Kinetic Model of TiN Particle Dissolution and Coarsening during Welding Thermal Cycle

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With carbon extraction replica technique, electron diffraction and EDAX analysis, second particle size distributionin two Ti microalloyed steels and their heat-affected zones were investigated. The results show that the particles inthe Ti microalloyed steels are TiN particles, and the TiN particles in the steel with lower Ti/N ratio exhibit smallersize and lower dissolution and coarsening rate and extent. Based on the investigation results, kinetic models for TiNparticle dissolution and coarsening during welding thermal cycle were developed. The predicted values calculated byusing the models are in good agreement with the experimental ones.

  2. How to extract information from simulations of coarsening at finite temperature

    Science.gov (United States)

    Derrida, B.

    1997-03-01

    Certain properties of coarsening phenomena such as the fraction of space which remains always in the same phase are hard to measure in simulations, at nonzero temperature, because one needs to distinguish spin flips due to thermal fluctuations from those due to the motion of interfaces. By comparing the system where coarsening takes place with a fully ordered system submitted to the same thermal noise, one can measure in a simple way the fraction of space which remains in the same phase. Our numerical results indicate a power law decay (of the fraction of persistent spins) in the whole low temperature phase very similar to the zero temperature situation.

  3. Critique of Coleman's Theory of the Vanishing Cosmological Constant

    Science.gov (United States)

    Susskind, Leonard

    In these lectures I would like to review some of the criticisms to the Coleman worm-hole theory of the vanishing cosmological constant. In particular, I would like to focus on the most fundamental assumption that the path integral over topologies defines a probability for the cosmological constant which has the form EXP(A) with A being the Baum-Hawking-Coleman saddle point. Coleman argues that the euclideam path integral over all geometries may be dominated by special configurations which consist of large smooth "spheres" connected by any number of narrow wormholes. Formally summing up such configurations gives a very divergent expression for the path integral…

  4. Standard cosmological model with non vanishing Weyl tensor

    CERN Document Server

    Bittencourt, E

    2013-01-01

    We have solved Einstein's equations of general relativity for a homogeneous and isotropic metric with constant spatial curvature and found a non vanishing Weyl tensor in the presence of an anisotropic pressure component of the energy-momentum tensor. The time evolution of the space-time is guided by the usual Friedman equations and the properties of the spatial components comprise a separated system of equations that can be independently solved. The physical features of this solution are elucidated by using the Quasi-Maxwellian equations of general relativity which directly connect the anisotropic pressure to the electric part of the Weyl tensor for the cosmological fluid.

  5. Vanishing of cohomology over Cohen--Macaulay rings

    CERN Document Server

    Christensen, Lars Winther

    2010-01-01

    A 2003 counterexample to a conjecture of Auslander brought attention to a family of rings - colloquially called AC rings - that satisfy a natural condition on vanishing of cohomology. Several results attest to the remarkable homological properties of AC rings, but their definition is barely operational, and it remains unknown if they form a class that is closed under typical constructions in ring theory. In this paper, we study transfer of the AC property along local homomorphisms of Cohen--Macaulay rings. In particular, we show that the AC property is preserved by standard procedures in local algebra. Our results also yield new examples of Cohen-Macaulay AC rings.

  6. Vanishing auxiliary variables in PPS sampling - with applications in microscopy

    DEFF Research Database (Denmark)

    Andersen, Ina Trolle; Hahn, Ute; Jensen, Eva B. Vedel

    Recently, non-uniform sampling has been suggested in microscopy to increase efficiency. More precisely, sampling proportional to size (PPS) has been introduced where the probability of sampling a unit in the population is proportional to the value of an auxiliary variable. Unfortunately, vanishing...... auxiliary variables are a common phenomenon in microscopy and, accordingly, part of the population is not accessible, using PPS sampling. We propose a modification of the design, for which an optimal solution can be found, using a model assisted approach. The optimal design has independent interest...

  7. Vanishing Matter and the Laws of Nature Descartes and Beyond

    CERN Document Server

    Anstey, Peter

    2010-01-01

    This volume explores the themes of vanishing matter, matter and the laws of nature, the qualities of matter, and the diversity of the debates about matter in the early modern period. Chapters are unified by a number of interlocking themes which together enable some of the broader contours of the philosophy of matter to be charted in new ways. Part I concerns Cartesian Matter; Part II covers Matter, Mechanism and Medicine; Part III covers Matter and the Laws of Motion; and Part IV covers Leibniz and Hume. Bringing together some of the world's leading scholars of early modern philosophy, as well

  8. Gauge theories from D7-branes over vanishing 4-cycles

    Energy Technology Data Exchange (ETDEWEB)

    Franco, Sebastian; /Santa Barbara, KITP; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.

    2010-12-16

    We study quiver gauge theories on D7-branes wrapped over vanishing holomorphic 4-cycles. We investigate how to incorporate O7-planes and/or flavor D7-branes, which are necessary to cancel anomalies. These theories are chiral, preserve four supercharges and exhibit very rich infrared dynamics. Geometric transitions and duality in the presence of O-planes are analyzed. We study the Higgs branch of these quiver theories, showing the emergence of fuzzy internal dimensions. This branch is related to noncommutative instantons on the divisor wrapped by the seven-branes. Our results have a natural application to the recently introduced F(uzz) limit of F-theory.

  9. 3D reconstruction based on spatial vanishing information

    Institute of Scientific and Technical Information of China (English)

    Yuan Shu; Zheng Tan

    2005-01-01

    An approach for the three-dimensional (3D) reconstruction of architectural scenes from two un-calibrated images is described in this paper. From two views of one architectural structure, three pairs of corresponding vanishing points of three major mutual orthogonal directions can be extracted. The simple but powerful constraints of parallelism and orthogonal lines in architectural scenes can be used to calibrate the cameras and to recover the 3D information of the structure. This approach is applied to the real images of architectural scenes, and a 3D model of a building in virtual reality modelling language (VRML) format is presented which illustrates the method with successful performance.

  10. Ursodeoxycholic acid treatment of vanishing bile duct syndromes

    Institute of Scientific and Technical Information of China (English)

    Thomas Pusl; Ulrich Beuers

    2006-01-01

    Vanishing bile duct syndromes (VBDS) are characterized by progressive loss of small intrahepatic ducts caused by a variety of different diseases leading to chronic cholestasis, cirrhosis, and premature death from liver failure. The majority of adult patients with VBDS suffer from primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Ursodeoxycholic acid (UDCA), a hydrophilic dihydroxy bile acid, is the only drug currently approved for the treatment of patients with PBC, and anticholestatic effects have been reported for several other cholestatic syndromes. Several potential mechanisms of action of UDCA have been proposed including stimulation of hepatobiliary secretion, inhibition of apoptosis and protection of cholangiocytes against toxic effects of hydrophobic bile acids.

  11. Is the Chiral Vortical Effect Vanishing in Heavy Ion Collisions?

    CERN Document Server

    Landsteiner, Karl; Pena-Benitez, Francisco

    2013-01-01

    We study the frequency dependence of all the chiral vortical and magnetic conductivities for a relativistic chiral gas of free fermions and for a strongly coupled CFT with holographic dual in four dimensions. Both systems present gauge and gravitational anomalies and we compute their contribution to the conductivities. The chiral vortical conductivities and the chiral magnetic conductivity in the energy current show an unexpected frequency dependence in the form of a delta centered at zero frequency. We argue that this makes the CVE practically unobservable in heavy ion collisions. In the appendix we discuss why the CME seems to vanish in the consistent current for a particular implementation of the axial chemical potential.

  12. James Luna and the Paradoxically Present Vanishing Indian

    Directory of Open Access Journals (Sweden)

    Elizabeth S Hawley

    2016-11-01

    Full Text Available James Luna’s performances interrogate how representations of Native Americans have been made to fit western assumptions about the “real Indian.” Using his recognizably Native body as a marker of both presence and endangered existence, Luna links Peggy Phelan’s conception of performance as the presence of loss with the centuries-old stereotype of Native Americans as the “vanishing race”—a stereotype that continues to exert influence. In Take a Picture with a Real Indian (performed in 1992, 2001, and 2010, he invites viewers to have their photograph taken with him wearing one of three options: war dance regalia, a loincloth, or khakis and a polo shirt. Few people choose the third option. The performance foregrounds what has become a tradition of Native Americans performing/posing their native -ness as Otherness for the camera, strategically employing imagery that plays to nostalgic Western views of Native peoples as perpetually vanishing. I argue that Luna’s performances comment not only upon western preconceptions of Native Americans, but also upon the ways that Native Americans have historically reasserted their agency by manipulating such expectations, staging themselves to fit the stereotype.

  13. Gravitational effects on vanishing Higgs potential at the Planck scale

    CERN Document Server

    Haba, Naoyuki; Takahashi, Ryo; Yamaguchi, Yuya

    2014-01-01

    We investigate gravitational effects on so-called multiple point criticality principle (MPCP) at the Planck scale. The MPCP requires two degenerate vacua, whose necessary conditions are expressed by vanishing Higgs quartic coupling ($\\lambda(M_{\\rm Pl})=0$) and vanishing its $\\beta$-function ($\\beta_\\lambda(M_{\\rm Pl})=0$). In order to satisfy the conditions, we find that the top pole mass and the Higgs mass should be $170.8\\,{\\rm GeV} \\lesssim M_t\\lesssim 171.7\\, {\\rm GeV}$ and $M_h=125.7\\pm0.4\\, {\\rm GeV}$, respectively, as well as suitable magnitude of gravitational effects (a coefficient of gravitational contribution as $|a_\\lambda| > 2$). In this case, however, since the Higgs quartic coupling $\\lambda$ becomes negative below the Planck scale, two vacua are not degenerate. We find that $M_h \\gtrsim 131.5\\, {\\rm GeV}$ with $M_t \\gtrsim 174\\, {\\rm GeV}$ is required by the realization of the MPCP. Therefore, the MPCP at the Planck scale cannot be realized in the SM and also the SM with gravity since $M_h \\g...

  14. Structural coarsening during annealing of an aluminum plate heavily deformed using ECAE

    DEFF Research Database (Denmark)

    Mishin, Oleg V.; Zhang, Yubin; Godfrey, A.

    2015-01-01

    The microstructure and softening behaviour have been investigated in an aluminum plate heavily deformed by equal channel angular extrusion and subsequently annealed at 170 °C. It is found that at this temperature the microstructure evolves by coarsening with no apparent signs of recrystallization...

  15. Multigrid method based on a space-time approach with standard coarsening for parabolic problems

    NARCIS (Netherlands)

    S.R. Franco (Sebastião Romero); F.J. Gaspar Lorenz (Franscisco); M.A. Villela Pinto (Marcio Augusto); C. Rodrigo (Carmen)

    2018-01-01

    textabstractIn this work, a space-time multigrid method which uses standard coarsening in both temporal and spatial domains and combines the use of different smoothers is proposed for the solution of the heat equation in one and two space dimensions. In particular, an adaptive smoothing strategy,

  16. Directional coarsening in nickel-base superalloys and its effect on the mechanical properties

    NARCIS (Netherlands)

    Tinga, T.; Brekelmans, W.A.M.; Geers, M.G.D.

    2009-01-01

    During high temperature loading, the regular microstructure of nickel-base superalloys consisting of a γ-matrix (Ni) containing a large volume fraction of γ′-particles (Ni3Al) degrades. The cubic precipitates coarsen and elongate in a direction normal to the applied stress in a process called raftin

  17. In-Situ Analysis of Coarsening during Directional Solidification Experiments in High-Solute Aluminum Alloys

    NARCIS (Netherlands)

    Ruvalcaba, D.; Mathiesen, R.H.; Eskin, D.G.; Arnberg, L.; Katgerman, L.

    2009-01-01

    Coarsening within the mushy zone during continuous directional solidification experiments was studied on an Al-30 wt pct Cu alloy. High brilliance synchrotron X-radiation microscopy allowed images to be taken in-situ during solidification. Transient conditions were present during directional solidif

  18. Microstructural Coarsening during Thermomechanical Fatigue and Annealing of Micro Flip-Chip Solder Joints

    Energy Technology Data Exchange (ETDEWEB)

    Barney, Monica Michele [Univ. of California, Berkeley, CA (United States)

    1998-12-01

    Microstructural evolution due to thermal effects was studied in micro solder joints (55 ± 5 μm). The composition of the Sn/Pb solder studied was found to be hypereutectic with a tin content of 65-70 wt%.This was determined by Energy Dispersive X-ray analysis and confirmed with quantitative stereology. The quantitative stereological value of the surface-to-volume ratio was used to characterize and compare the coarsening during thermal cycling from 0-160 C to the coarsening during annealing at 160 C. The initial coarsening of the annealed samples was more rapid than the cycled samples, but tapered off as time to the one-half as expected. Because the substrates to which the solder was bonded have different thermal expansion coefficients, the cycled samples experienced a mechanical strain with thermal cycling. The low-strain cycled samples had a 2.8% strain imposed on the solder and failed by 1,000 cycles, despite undergoing less coarsening than the annealed samples. The high-strain cycled samples experienced a 28% strain and failed between 25 and 250 cycles. No failures were observed in the annealed samples. Failure mechanisms and processing issues unique to small, fine pitch joints are also discussed.

  19. Vanishing, moving and immovable interfaces in fast reaction limits

    Science.gov (United States)

    Iida, M.; Monobe, H.; Murakawa, H.; Ninomiya, H.

    2017-09-01

    We consider a type of singular limit problem called the fast reaction limit. The problem of the fast reaction limit involves studying the behaviour of solutions of reaction-diffusion systems when the reaction speeds are very fast. Fast reaction limits of two-component systems have been studied in recent decades. In most of these systems, the fast reaction terms of each component are represented by the same function. Fast reaction limits of systems with different fast reaction terms are still far from being well understood. In this paper, we focus on a reaction-diffusion system for which the reaction terms consist of monomial functions of various powers. The behaviour of interfaces arising in the fast reaction limit of this system is studied. Depending on the powers, three types of behaviour are observed: (i) the initial interface vanishes instantaneously, (ii) the interface propagates at a finite speed, and (iii) the interface does not move.

  20. Non-supersymmetric Asymmetric Orbifolds with Vanishing Cosmological Constant

    CERN Document Server

    Satoh, Yuji; Wada, Taiki

    2015-01-01

    We study type II string vacua defined by torus compactifications accompanied by T-duality twists. We realize the string vacua, specifically, by means of the asymmetric orbifolding associated to the chiral reflections combined with a shift, which are interpreted as describing the compactification on `T-folds'. We discuss possible consistent actions of the chiral reflection on the Ramond-sector of the world-sheet fermions, and explicitly construct non-supersymmetric as well as supersymmetric vacua. Above all, we demonstrate a simple realization of non-supersymmetric vacua with vanishing cosmological constant at one loop. Our orbifold group is generated only by a single element, which results in simpler models than those with such property known previously.

  1. Non-supersymmetric asymmetric orbifolds with vanishing cosmological constant

    Science.gov (United States)

    Satoh, Yuji; Sugawara, Yuji; Wada, Taiki

    2016-02-01

    We study type II string vacua defined by torus compactifications accompanied by T-duality twists. We realize the string vacua, specifically, by means of the asymmetric orbifolding associated to the chiral reflections combined with a shift, which are interpreted as describing the compactification on `T-folds'. We discuss possible consistent actions of the chiral reflection on the Ramond-sector of the world-sheet fermions, and explicitly construct non-supersymmetric as well as supersymmetric vacua. Above all, we demonstrate a simple realization of non-supersymmetric vacua with vanishing cosmological constant at one loop. Our orbifold group is generated only by a single element, which results in simpler models than those with such property known previously.

  2. [THE HISTORY OF A VANISHED PHARMACY IN ROME].

    Science.gov (United States)

    Serarcangeli, Carla

    2015-01-01

    Starting from archive documents, the present article aims to retrace the history of a once well-known pharmacy based in S. Eustachio square, in Rome, and then commonly denominated Corsi's. Thanks to the information gathered in Roman archives, it is possible to throw light on the events related to this apothecary, whose activity, as found out, lasted since the XVIII until the first decades of the XX century, under the property of two families, first the Conti and then the Corsi. Notwithstanding its long establishment, this pharmacy seems to have suddenly vanished from the official documents registered within the archives. Nevertheless the importance of its history is actually related to some of the instruments, being part of its original inventory, and nowadays held in the collection of the Museum of History of Medicine in Rome. These specimens particularly jars and boxes, are valuable in order to describe how in the past professionals used to take care of most of the diseases.

  3. Mycophenolate mofetil for drug-induced vanishing bile duct syndrome

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Amoxicillin/clavulanate is associated with liver injury,mostly of a cholestatic pattern. While outcomes are usually benign, progression to cirrhosis and death has been reported. The role of immunosuppressive therapy for patients with a protracted course is unclear. We report the case of an elderly patient who developed prolonged cholestasis secondary to amoxicillin/clavulanate. Vanishing bile duct syndrome was confirmed by sequential liver biopsies. The patient responded to prednisone treatment,but could not be weaned off corticosteroids, even when azathioprine was added. Complete withdrawal of both prednisone and azathioprine was possible by using mycophenolate mofetil, an inosine monophosphate dehydrogenase inhibitor. Sustained remission has been maintained for more than 3 years with low-dose mycophenolate mofetil.

  4. Cones in the Euclidean space with vanishing scalar curvature

    Directory of Open Access Journals (Sweden)

    João Lucas M. Barbosa

    2004-12-01

    Full Text Available Given a hypersurface M on a unit sphere of the Euclidean space, we define the cone based on M as the set of half-lines issuing from the origin and passing through M. By assuming that the scalar curvature of the cone vanishes, we obtain conditions under which bounded domains of such cone are stable or unstable.Dada uma hipersuperfície M de uma esfera unitária do espaço euclidiano, definimos o cone sobre M como o conjunto das semi-retas que saem da origem e passam por M. Admitindo que a curvatura escalar de um dado cone é nula, estabelecemos condições para que os seus domínios limitados sejam estáveis ou instáveis.

  5. Electrostatic interactions of colloidal particles at vanishing ionic strength.

    Science.gov (United States)

    Sainis, Sunil K; Merrill, Jason W; Dufresne, Eric R

    2008-12-02

    Electrostatic interactions of colloidal particles are typically screened by mobile ions in the solvent. We measure the forces between isolated pairs of colloidal polymer microspheres as the density of bulk ions vanishes. The ionic strength is controlled by varying the concentration of surfactant (NaAOT) in a nonpolar solvent (hexadecane). While interactions are well-described by the familiar screened-Coulomb form at high surfactant concentrations, they are experimentally indistinguishable from bare Coulomb interactions at low surfactant concentration. Interactions are strongest just above the critical micelle concentration, where particles can obtain high surface potentials without significant screening, kappaa renormalization, we are able to construct a simple thermodynamic model capturing the role of reverse micelles in charging the particle surface. These measurements provide novel access to electrostatic forces in the limit where the particle size is much less than the screening length, which is relevant not just to the nonpolar suspensions described here, but also to aqueous suspensions of nanoparticles.

  6. Vanishing of the Top Local Cohomology Modules over Noetherian Rings

    Indian Academy of Sciences (India)

    Kamran Divaani-Aazar

    2009-02-01

    Let be a (not necessarily local) Noetherian ring and a finitely generated -module of finite dimension . Let $\\mathfrak{a}$ be an ideal of and $\\mathfrak{M}$ denote the intersection of all prime ideals $\\mathfrak{p}\\in\\mathrm{Supp}_R H^d_a(M)$. It is shown that $$H^d_a(M)\\simeq H^d_{\\mathfrak{M}}(M)/\\sum\\limits_{n\\in\\mathbb{N}}\\langle \\mathfrak{M}\\rangle(0:_{H^d_{\\mathfrak{M}}(M)}a^n),$$ where for an Artinian -module we put $\\langle\\mathfrak{M}\\rangle A=\\cap_{n\\in\\mathbb{N}}\\mathfrak{M}^n A$. As a consequence, it is proved that for all ideals $\\mathfrak{a}$ of , there are only finitely many non-isomorphic top local cohomology modules $H^d_a(M)$ having the same support. In addition, we establish an analogue of the Lichtenbaum–Hartshorne vanishing theorem over rings that need not be local.

  7. Coarsening of Inter- and Intra-granular Proeutectoid Cementite in an Initially Pearlitic 2C-4Cr Ultrahigh Carbon Steel

    Science.gov (United States)

    Hecht, Matthew D.; Picard, Yoosuf N.; Webler, Bryan A.

    2017-05-01

    We have examined spheroidization and coarsening of cementite in an initially pearlitic 2C-4Cr ultrahigh carbon steel containing a cementite network. Coarsening kinetics of spheroidized cementite and growth of denuded zones adjacent to the cementite network were investigated by analyzing particle sizes from digital micrographs of water-quenched steel etched with Nital. Denuded zones grew at a rate proportional to t 1/4- t 1/5. Spheroidization of pearlite was completed within 90 minutes at 1073 K and 1173 K (800 °C and 900 °C), and within 5 minutes at 1243 K (970 °C). Bimodal particle size distributions were identified in most of the samples and were more pronounced at higher temperatures and hold times. Peaks in the distributions were attributed to the coarsening of intragranular and grain boundary particles at different rates. A third, non-coarsening peak of particles was present at 1073 K (800 °C) only and was attributed to particles existing prior to the heat treatment. Particle sizes were plotted vs time to investigate possible coarsening mechanisms. The coarsening exponent for the growth of grain boundary carbides was closest to 4, indicating grain boundary diffusion control. The coarsening exponent was closest to 5 for intragranular carbides, indicating suppression of volumetric diffusion (possibly due to reduced effective diffusivity because of Cr alloying) and control by dislocation diffusion.

  8. Coarsening of Dendrites in Solid-Liquid Mixtures under Microgravity: Experiments and Phase Field Simulations

    Science.gov (United States)

    Cool, Thomas

    The morphological and topological evolution of dendritic structures during coarsening remains poorly understood. In particular, predicting the fissioning of secondary arms from the main dendrite stem and coalescence and retraction events remains controversial. We perform experiments on the International Space Station (ISS) since arms that fission from the stem do not sediment and thus can be detected. In addition, it is also possible to follow the morphological evolution of the structure in the absence of convection. 30% Pb-Sn samples were coarsened for different lengths of time from 10 min to 48 hrs. The morphology of the structure and the number of fissioned arms were determined using three-dimensional reconstructions. The evolution of the microstructure, the change in length scale, the number of independent bodies, the evolution of the anisotropy of the structure and the interfacial shape distributions as a function of time during coarsening were studied. Key findings are that 1) the inverse of surface area per unit volume SV -1 increases with time as t1/3 that is almost identical to a sample coarsened on earth; 2) independent bodies were found in all samples; 3) the number of independent bodies per unit volume multiplied by SV-3 is independent of coarsening time. Thus it is possible to predict the number of fragments during coarsening by a measurement of SV; 4) the genus scaled by SV{-3}$ is independent of coarsening time. A 3D reconstruction of a PbSn sample, 30% solid, that was coarsened aboard the ISS was used as an initial condition in a phase-field model to study pinching (fisioning), retraction and coalescence (fusioning) of secondary dendrite arms. The overall simulation box was 472x496x248 voxels; the phase field model was coded in OpenCL to run on a D700 FirePro GPU. In spite of the high speed of the simulations, evolving the PbSn structure from 10 min to 1.6 hrs still required 23 days. Two variants were run of the model that differ along the length of

  9. Grain Coarsening Behavior of Mg-Al Alloys with Mischmetal Addition

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Small addition of mischmetal (MM) into aluminum alloys can lead to grain refinement. However, it is still uncertain whether the same effect applies to Mg-Al alloys. This work indicated that small amount of mischmetal addition ranging from 0.1% to 1.2% (mass fraction) did not cause grain refinement in Mg-Al alloys. On the contrary, they tended to coarsen the grains. When added into Mg-Al alloys, MM reacted preferentially with Al to form Al11MM3 phase. As Al11MM3 phase mainly distributed within α-Mg grains than at grain boundaries, it had little effect in restricting grain growth. In addition, MM reacted with Al8(Mn, Fe)5 or ε-AlMn particles to form Al-MM-Mn compounds, thus it reduced the amount of heterogeneous nuclei in the melt and resulted in remarkable grain coarsening.

  10. Competition of coarsening and shredding of clusters in a driven diffusive lattice gas

    CERN Document Server

    Kunwar, A; Schadschneider, A; Nishinari, K; Kunwar, Ambarish; Chowdhury, Debashish; Schadschneider, Andreas; Nishinari, Katsuhiro

    2006-01-01

    We investigate a driven diffusive lattice gas model with two oppositely moving species of particles. The model is motivated by bi-directional traffic of ants on a pre-existing trail. A third species, corresponding to pheromones used by the ants for communication, is not conserved and mediates interactions between the particles. Here we study the spatio-temporal organization of the particles. In the uni-directional variant of this model it is known to be determined by the formation and coarsening of ``loose clusters''. For our bi-directional model, we show that the interaction of oppositely moving clusters is essential. In the late stages of evolution the cluster size oscillates because of a competition between their `shredding' during encounters with oppositely moving counterparts and subsequent "coarsening" during collision-free evolution. We also establish a nontrivial dependence of the spatio-temporal organization on the system size.

  11. The development of directional coarsening of the gamma-prime precipitate in superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1983-01-01

    A study has been made of the kinetics of the directional coarsening of the gamma-prime precipitates in Ni-5.8Al-14.6Mo-6.2Ta single crystals during creep at 982 C. In this alloy, which is characterized by a large negative lattice misfit between the gamma-prime precipitate and the gamma matrix, the formation of gamma-prime rafts begins during primary creep, and the rafts grow in length as the deformation proceeds into steady-state creep. After that, the length of the rafts stabilizes. The thickness of the rafts remains constant from primary up to tertiary creep. The directional coarsening behavior of the alloy studied is similar to that of a more conventional single-crystal superalloy having a substantially smaller negative misfit.

  12. Grain Coarsening of Hematite in the Gushan Iron Deposit,Anhui Province,China

    Institute of Scientific and Technical Information of China (English)

    顾连兴; 阮惠础; 等

    1997-01-01

    The iron ores of the Gushan mine occur in the contact zone of a Mesozoic diorite intrusion and are composed primarily of hematite microcrystallites and chalcedony,The hematite microcrystallites have undergone post-mineralization recrystallization and coarsening with resultant formation of lath-shaped hematite porphyroblasts.Microscopic investigation reveals that recrystallization and coarsening of the hematite ores of the Gushan mine took place without the formation of new nuclei,due to the coalescence of the microcrystallites.The whole process could have begun with the mutual approach of the microcrystallites,followed by grain rotation to realize paralleism and ending by the welding of these grains to form optically homogeneous porphyroblastic hematite.

  13. Three is much more than two in coarsening dynamics of cyclic competitions

    Science.gov (United States)

    Mitarai, Namiko; Gunnarson, Ivar; Pedersen, Buster Niels; Rosiek, Christian Anker; Sneppen, Kim

    2016-04-01

    The classical game of rock-paper-scissors has inspired experiments and spatial model systems that address the robustness of biological diversity. In particular, the game nicely illustrates that cyclic interactions allow multiple strategies to coexist for long-time intervals. When formulated in terms of a one-dimensional cellular automata, the spatial distribution of strategies exhibits coarsening with algebraically growing domain size over time, while the two-dimensional version allows domains to break and thereby opens the possibility for long-time coexistence. We consider a quasi-one-dimensional implementation of the cyclic competition, and study the long-term dynamics as a function of rare invasions between parallel linear ecosystems. We find that increasing the complexity from two to three parallel subsystems allows a transition from complete coarsening to an active steady state where the domain size stays finite. We further find that this transition happens irrespective of whether the update is done in parallel for all sites simultaneously or done randomly in sequential order. In both cases, the active state is characterized by localized bursts of dislocations, followed by longer periods of coarsening. In the case of the parallel dynamics, we find that there is another phase transition between the active steady state and the coarsening state within the three-line system when the invasion rate between the subsystems is varied. We identify the critical parameter for this transition and show that the density of active boundaries has critical exponents that are consistent with the directed percolation universality class. On the other hand, numerical simulations with the random sequential dynamics suggest that the system may exhibit an active steady state as long as the invasion rate is finite.

  14. Graphene oxide-promoted reshaping and coarsening of gold nanorods and nanoparticles.

    Science.gov (United States)

    Pan, Hanqing; Low, Serena; Weerasuriya, Nisala; Shon, Young-Seok

    2015-02-11

    This paper describes thermally induced reshaping and coarsening behaviors of gold nanorods and nanoparticles immobilized on the surface of graphene oxide. Cetyltrimethylammonium bromide-stabilized gold nanorods with an aspect ratio of ∼3.5 (54:15 nm) and glutathione-capped gold nanoparticles with an average core size of ∼3 nm were synthesized and self-assembled onto the surface of graphene oxide. The hybrid materials were then heated at different temperatures ranging from 50 to 300 °C. The effects of heat treatments were monitored using UV-vis spectroscopy and transmission electron microscopy (TEM). These results were directly compared with those of heat-treated free-standing gold nanorods and nanoparticles without graphene oxide to understand the heat-induced morphological changes of the nanohybrids. The obtained results showed that the gold nanorods would undergo a complete reshaping to spherical particles at the temperature of 50 °C when they are assembled on graphene oxide. In comparison, the complete reshaping of free-standing gold nanorods to spherical particles would ultimately require a heating of the samples at 200 °C. In addition, the spherical gold nanoparticles immobilized on graphene oxide would undergo a rapid coarsening at the temperature of 100-150 °C, which was lower than the temperature (150-200 °C) required for visible coarsening of free-standing gold nanoparticles. The results indicated that graphene oxide facilitates the reshaping and coarsening of gold nanorods and nanoparticles, respectively, during the heat treatments. The stripping and spillover of stabilizing ligands promoted by graphene oxide are proposed to be the main mechanism for the enhancements in the heat-induced transformations of nanohybrids.

  15. Symmetry breaking and coarsening of clusters in a prototypical driven granular gas

    OpenAIRE

    Livne, Eli; Meerson, Baruch; Sasorov, Pavel V.

    2002-01-01

    Granular hydrodynamics predicts symmetry-breaking instability in a two-dimensional (2D) ensemble of nearly elastically colliding smooth hard spheres driven, at zero gravity, by a rapidly vibrating sidewall. Super- and subcritical symmetry-breaking bifurcations of the simple clustered state are identified, and the supercritical bifurcation curve is computed. The cluster dynamics proceed as a coarsening process mediated by the gas phase. Far above the bifurcation point the final steady state, s...

  16. Ni coarsening in the three-phase solid oxide fuel cell anode - a phase-field simulation study

    CERN Document Server

    Chen, Hsun-Yi; Cronin, J Scott; Wilson, James R; Barnett, Scott A; Thornton, Katsuyo

    2012-01-01

    Ni coarsening in Ni-yttria stabilized zirconia (YSZ) solid oxide fuel cell anodes is considered a major reason for anode degradation. We present a predictive, quantative modeling framework based on the phase-field approach to systematically examine coarsening kinetics in such anodes. The initial structures for simulations are experimentally acquired functional layers of anodes. Sample size effects and error analysis of contact angles are examined. Three phase boundary (TPB) lengths and Ni surface areas are quantatively identified on the basis of the active, dead-end, and isolated phase clusters throughout coarsening. Tortuosity evolution of the pores is also investigated. We find that phase clusters with larger characteristic length evolve slower than those with smaller length scales. As a result, coarsening has small positive effects on transport, and impacts less on the active Ni surface area than the total counter part. TPBs, however, are found to be sensitive to local morphological features and are only i...

  17. Coarsening Dynamics and Marangoni Effects in Thin Liquid Crystal Bubbles in Microgravity

    Science.gov (United States)

    Clark, Noel; Glaser, Matthew; Maclennan, Joseph; Park, Cheol; Tin, Padetha; Hall, Nancy R.; Sheehan, Christopher; Storck, Jennifer

    2015-01-01

    The Observation and Analysis of Smectic Islands in Space (OASIS) flight hardware was successfully launched on SpaceX-6 on April 15, 2015 and was operated in the Microgravity Science Glovebox (MSG) on board the International Space Station (ISS). The OASIS project comprises a series of experiments that probe the interfacial and hydrodynamic behavior of spherical-bubble freely suspended liquid crystal (FSLC) membranes in space. These are the thinnest known stable condensed phase structures, making them ideal for studies of two-dimensional (2D) coarsening dynamics and thermocapillary phenomena in microgravity. The OASIS experimental investigation was carried out using four different smectic A and C liquid crystal materials in four separate sample chambers housed inside the MSG. In this report, we present the behavior of collective dynamics on 2D bubble surface, including the equilibrium spatial organization and interaction of islands in electric fields and temperature gradients, and the diffusion and coalescence-driven coarsening dynamics of island emulsions in microgravity. We have observed spontaneous bubble thickening behavior caused by gradients between the bubble-blowing needle and ambient air temperatures. A uniform, thicker band forms during coarsening as a result of non-uniform heating by the LED illumination panels. These are proposed to be a result of Marangoni convection on the bubble surface.

  18. Coarsening and clustering in run-and-tumble dynamics with short-range exclusion

    CERN Document Server

    Sepulveda, Nestor

    2016-01-01

    The emergence of clustering and coarsening in crowded ensembles of self-propelled agents is studied using a lattice model in one-dimension. The persistent exclusion process, where particles move at directions that change randomly at a low tumble rate $\\alpha$, is extended allowing sites to be occupied by more than one particle, with a maximum $n_\\text{max}$ per site. Three phases are distinguished. For $n_\\text{max}=1$ a gas of clusters form, with sizes distributed exponentially and no coarsening takes place. For $n_\\text{max}\\geq 3$ and small values of $\\alpha$, coarsening takes place and few large clusters appear, with a large fraction of the total number of particles in them. In the same range of $n_\\text{max}$ but for larger values of $\\alpha$, a gas phase where a negligible fraction of particles takes part of clusters. Finally, $n_\\text{max}=2$ corresponds to a crossover phase. The character of the transitions between phases is studied extending the model to allow $n_\\text{max}$ to take real values and j...

  19. Nanoscale gutter hydrodynamics: asymmetric vanishing lifetime of identical twin nanodroplets

    Science.gov (United States)

    Tiwari, Dhirendra; Dijkstra, Marcel; Eijkel, Jan; Gardeniers, Han; Mercury, Lionel; Tas, Niels; Vanapalli, Srinivas

    2015-11-01

    We study the capillary behavior of wetting liquids in the context of receding liquid fronts capped with an unsaturated zone (UZ) in a model 2D-porous media and report on the removal of liquid from an array of square nanodroplets inter-connected through nanoscopic-gutters. At the tip of the array a quasi 2D pinch-off generates identical twin nanodroplets marked by the singularity in local liquid pressure. The temporal violation of Lord Kelvin's equation kicks off the hydraulic conduction among nearest-neighbor droplets. A simple exponential decay/growth fluidic model incorporating constant evaporation rate validates the experimentally observed asymmetric vanishing life-time of the identical twin-droplets. Overall, this work illustrates the critical role of capillarity, wetting and geometry in setting up a unique scenario of ubiquitous competition among evaporation vs hydrodynamic conduction at meso-scale. The evaporating array of nanodroplets visualizes the tip of dynamic local vapor pressure gradient and captures the details of transport at an unprecedented size scale. DT acknowledges financial support from ISTO CNRS Orleans France and NWO The Netherlands.

  20. Vanishing tattoo multi-sensor for biomedical diagnostics

    Science.gov (United States)

    Moczko, E.; Meglinski, I.; Piletsky, S.

    2008-04-01

    Currently, precise non-invasive diagnostics systems for the real-time multi detection and monitoring of physiological parameters and chemical analytes in the human body are urgently required by clinicians, physiologists and bio-medical researchers. We have developed a novel cost effective smart 'vanishing tattoo' (similar to temporary child's tattoos) consisting of environmental-sensitive dyes. Painlessly impregnated into the skin the smart tattoo is capable of generating optical/fluorescence changes (absorbance, transmission, reflectance, emission and/or luminescence within UV, VIS or NIR regions) in response to physical or chemical changes. These changes allow the identification of colour pattern changes similar to bar-code scanning. Such a system allows an easy, cheap and robust comprehensive detection of various parameters and analytes in a small volume of sample (e.g. variations in pH, temperature, ionic strength, solvent polarity, presence of redox species, surfactants, oxygen). These smart tattoos have possible applications in monitoring the progress of disease and transcutaneous drug delivery. The potential of this highly innovative diagnostic tool is wide and diverse and can impact on routine clinical diagnostics, general therapeutic management, skin care and cosmetic products testing as well as fundamental physiological investigations.

  1. Graph coarsening methods for Karush-Kuhn-Tucker matrices arising in orthogonal collocation of optimal control problems

    Science.gov (United States)

    Senses, Begum

    A state-defect constraint pairing graph coarsening method is described for improving computational efficiency during the numerical factorization of large sparse Karush-Kuhn-Tucker matrices that arise from the discretization of optimal control problems via a Legendre-Gauss-Radau orthogonal collocation method. The method takes advantage of the particular sparse structure of the Karush-Kuhn-Tucker matrix that arises from the orthogonal collocation method. The state-defect constraint pairing graph coarsening method pairs each component of the state with its corresponding defect constraint and forces paired rows to be adjacent in the reordered Karush-Kuhn-Tucker matrix. Aggregate state-defect constraint pairing results are presented using a wide variety of benchmark optimal control problems where it is found that the proposed state-defect constraint pairing graph coarsening method significantly reduces both the number of delayed pivots and the number of floating point operations and increases the computational efficiency by performing more floating point operations per unit time. It is then shown that the state-defect constraint pairing graph coarsening method is less effective on Karush-Kuhn-Tucker matrices arising from Legendre-Gauss-Radau collocation when the optimal control problem contains state and control equality path constraints because such matrices may have delayed pivots that correspond to both defect and path constraints. An unweighted alternate graph coarsening method that employs maximal matching and a weighted alternate graph coarsening method that employs Hungarian algorithm on a weighting matrix are then used to attempt to further reduce the number of delayed pivots. It is found, however, that these alternate graph coarsening methods provide no further advantage over the state-defect constraint pairing graph coarsening method.

  2. Parallel kinetic Monte Carlo simulations of Ag(111) island coarsening using a large database

    Energy Technology Data Exchange (ETDEWEB)

    Nandipati, Giridhar; Shim, Yunsic; Amar, Jacques G [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Karim, Altaf [Brookhaven National Laboratory, Upton, NY 11973 (United States); Kara, Abdelkader; Rahman, Talat S [Department of Physics and Astronomy, University of Central Florida, Orlando, FL 32816 (United States); Trushin, Oleg [Institute of Microelectronics and Informatics, Academy of Sciences of Russia, Yaroslavl 150007 (Russian Federation)], E-mail: jamar@physics.utoledo.edu

    2009-02-25

    The results of parallel kinetic Monte Carlo (KMC) simulations of the room-temperature coarsening of Ag(111) islands carried out using a very large database obtained via self-learning KMC simulations are presented. Our results indicate that, while cluster diffusion and coalescence play an important role for small clusters and at very early times, at late time the coarsening proceeds via Ostwald ripening, i.e. large clusters grow while small clusters evaporate. In addition, an asymptotic analysis of our results for the average island size S(t) as a function of time t leads to a coarsening exponent n = 1/3 (where S(t){approx}t{sup 2n}), in good agreement with theoretical predictions. However, by comparing with simulations without concerted (multi-atom) moves, we also find that the inclusion of such moves significantly increases the average island size. Somewhat surprisingly we also find that, while the average island size increases during coarsening, the scaled island-size distribution does not change significantly. Our simulations were carried out both as a test of, and as an application of, a variety of different algorithms for parallel kinetic Monte Carlo including the recently developed optimistic synchronous relaxation (OSR) algorithm as well as the semi-rigorous synchronous sublattice (SL) algorithm. A variation of the OSR algorithm corresponding to optimistic synchronous relaxation with pseudo-rollback (OSRPR) is also proposed along with a method for improving the parallel efficiency and reducing the number of boundary events via dynamic boundary allocation (DBA). A variety of other methods for enhancing the efficiency of our simulations are also discussed. We note that, because of the relatively high temperature of our simulations, as well as the large range of energy barriers (ranging from 0.05 to 0.8 eV), developing an efficient algorithm for parallel KMC and/or SLKMC simulations is particularly challenging. However, by using DBA to minimize the number of

  3. Vanishing twins: a predictor of small-for-gestational age in IVF singletons

    DEFF Research Database (Denmark)

    Pinborg, Anja; Lidegaard, Ojvind; Freiesleben, Nina la Cour

    2007-01-01

    The purpose of this study was to assess the effect of a vanishing twin on the risk of being small-for-gestational age (SGA) in in vitro fertilization (IVF) singletons.......The purpose of this study was to assess the effect of a vanishing twin on the risk of being small-for-gestational age (SGA) in in vitro fertilization (IVF) singletons....

  4. Vanishing twins: a predictor of small-for-gestational age in IVF singletons

    DEFF Research Database (Denmark)

    Pinborg, Anja; Lidegaard, Ojvind; Freiesleben, Nina la Cour

    2007-01-01

    The purpose of this study was to assess the effect of a vanishing twin on the risk of being small-for-gestational age (SGA) in in vitro fertilization (IVF) singletons.......The purpose of this study was to assess the effect of a vanishing twin on the risk of being small-for-gestational age (SGA) in in vitro fertilization (IVF) singletons....

  5. [To rescue a vanishing obstetric skill--vaginal breech delivery].

    Science.gov (United States)

    Glezerman, Marek

    2011-02-01

    In 2000, a large randomized controlled trial was published (Term Breech Trial - TBT). The authors concluded that cesarean section (CS) was safer for newborns in breech presentation than vaginal breech delivery (VBD). This conclusion was endorsed by major professional institutions, was adopted almost immediately by the medical community and led to a wholesale abandonment of planned VBD in the western world, including Israel. In past years, serious criticism has been voiced related to the methodology applied in the TBT and numerous studies have contradicted the recommendations. Subsequently, the professional institutions published revised guidelines with the recommendation that pregnant women with breech presentation should, under certain circumstances, be given the choice between CS and VBD. Yet, in most delivery wards, following a decade of abandonment of VBD, the expertise for this technique had almost vanished. An unbearable situation had materialized: CS increases maternal mortality and morbidity when compared to vaginal delivery but most obstetricians are no longer capable of offering women the choice of VBD. Recently, and with the support of the Israel Societies of Obstetrics and Gynecology and Feto-Maternal Medicine, representatives of 17 obstetrical departments convened and decided on urgent steps to revive VBD, including updating the relevant clinical guidelines and informed consent forms and, most importantly, to issue a call to train obstetricians in VBD. In March 2010, a workshop dedicated to breech delivery was conducted at the Beilinson Hospital, with the representatives of most Israeli hospitals and specialists from abroad. Subsequently, and at the same hospital, a week-long program for VBD was conducted at which approximately 30 obstetricians received hands-on training. Time will show if "turning back the tide" will help to progress into a safer future for women with breech presentation and to annually avoid between 1000 and 2000 needless cesarean

  6. Adaptive Wavelet Methods for Linear and Nonlinear Least-Squares Problems

    NARCIS (Netherlands)

    Stevenson, R.

    2014-01-01

    The adaptive wavelet Galerkin method for solving linear, elliptic operator equations introduced by Cohen et al. (Math Comp 70:27-75, 2001) is extended to nonlinear equations and is shown to converge with optimal rates without coarsening. Moreover, when an appropriate scheme is available for the appr

  7. Wave equation with concentrated nonlinearities

    OpenAIRE

    Noja, Diego; Posilicano, Andrea

    2004-01-01

    In this paper we address the problem of wave dynamics in presence of concentrated nonlinearities. Given a vector field $V$ on an open subset of $\\CO^n$ and a discrete set $Y\\subset\\RE^3$ with $n$ elements, we define a nonlinear operator $\\Delta_{V,Y}$ on $L^2(\\RE^3)$ which coincides with the free Laplacian when restricted to regular functions vanishing at $Y$, and which reduces to the usual Laplacian with point interactions placed at $Y$ when $V$ is linear and is represented by an Hermitean m...

  8. An atomistically informed mesoscale model for growth and coarsening during discharge in lithium-oxygen batteries

    Energy Technology Data Exchange (ETDEWEB)

    Welland, Michael J.; Lau, Kah Chun; Redfern, Paul C.; Wolf, Dieter; Curtiss, Larry A., E-mail: curtiss@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liang, Linyun [Mathematics and Computer Science, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zhai, Denyun [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2015-12-14

    An atomistically informed mesoscale model is developed for the deposition of a discharge product in a Li-O{sub 2} battery. This mescocale model includes particle growth and coarsening as well as a simplified nucleation model. The model involves LiO{sub 2} formation through reaction of O{sub 2}{sup −} and Li{sup +} in the electrolyte, which deposits on the cathode surface when the LiO{sub 2} concentration reaches supersaturation in the electrolyte. A reaction-diffusion (rate-equation) model is used to describe the processes occurring in the electrolyte and a phase-field model is used to capture microstructural evolution. This model predicts that coarsening, in which large particles grow and small ones disappear, has a substantial effect on the size distribution of the LiO{sub 2} particles during the discharge process. The size evolution during discharge is the result of the interplay between this coarsening process and particle growth. The growth through continued deposition of LiO{sub 2} has the effect of causing large particles to grow ever faster while delaying the dissolution of small particles. The predicted size evolution is consistent with experimental results for a previously reported cathode material based on activated carbon during discharge and when it is at rest, although kinetic factors need to be included. The approach described in this paper synergistically combines models on different length scales with experimental observations and should have applications in studying other related discharge processes, such as Li{sub 2}O{sub 2} deposition, in Li-O{sub 2} batteries and nucleation and growth in Li-S batteries.

  9. An atomistically informed mesoscale model for growth and coarsening during discharge in lithium-oxygen batteries

    Energy Technology Data Exchange (ETDEWEB)

    Welland, Michael J. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Lau, Kah Chun [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Redfern, Paul C. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Liang, Linyun [Mathematics and Computer Science, Argonne National Laboratory, Argonne, Illinois 60439, USA; Zhai, Denyun [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Wolf, Dieter [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Curtiss, Larry A. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

    2015-12-14

    An atomistically informed mesoscale model is developed for the deposition of a discharge product in a Li-O-2 battery. This mescocale model includes particle growth and coarsening as well as a simplified nucleation model. The model involves LiO2 formation through reaction of O-2(-) and Li+ in the electrolyte, which deposits on the cathode surface when the LiO2 concentration reaches supersaturation in the electrolyte. A reaction-diffusion (rate-equation) model is used to describe the processes occurring in the electrolyte and a phase-field model is used to capture microstructural evolution. This model predicts that coarsening, in which large particles grow and small ones disappear, has a substantial effect on the size distribution of the LiO2 particles during the discharge process. The size evolution during discharge is the result of the interplay between this coarsening process and particle growth. The growth through continued deposition of LiO2 has the effect of causing large particles to grow ever faster while delaying the dissolution of small particles. The predicted size evolution is consistent with experimental results for a previously reported cathode material based on activated carbon during discharge and when it is at rest, although kinetic factors need to be included. The approach described in this paper synergistically combines models on different length scales with experimental observations and should have applications in studying other related discharge processes, such as Li2O2 deposition, in Li-O-2 batteries and nucleation and growth in Li-S batteries.

  10. Effect of TaC Particles Dissolution on Grain Coarsening in Reduced Activation Steels

    Institute of Scientific and Technical Information of China (English)

    XIA Zhi-xin; ZHANG Chi; HUANG Qun-ying; LIU Shao-jun; LI Zhao-dong; YANG Zhi-gang

    2011-01-01

    The effect of TaC on grains and packets coarsening in the reduced activation ferritic/martensitic (RAFM) steels was investigated. It was found that the combined effect of the austenitizing temperature and heating rate resulted in the heterogeneous austenite grain growth. When the austenitizing temperature was raised above 1 423 K, the TaC particles disappeared, and the homogenous grains abruptly increased. The thermodynamic model for dissolution of TaC particles during austenitizing was applied to interpret the results.

  11. Coarsening in an interfacial equation without slope selection revisited: Analytical results

    Energy Technology Data Exchange (ETDEWEB)

    Guedda, M., E-mail: guedda@u-picardie.f [LAMFA, CNRS UMR 6140, Universite de Picardie Jules Verne, Amiens (France); Trojette, H. [LAMFA, CNRS UMR 6140, Universite de Picardie Jules Verne, Amiens (France)

    2010-09-20

    In this Letter, we re-examen a one-dimensional model of epitaxial growth that describes pyramidal structures characterized by the absence of a preferred slope [L. Golubovic, Phys. Rev. Lett. 78 (1997) 90]. A similarity approach shows that the typical mound lateral size and the interfacial width growth with time like t{sup 1/2} and t{sup 1/4}, respectively. This result was previously presented by Golubovic. Our contribution provides a mathematical justification for the existence of similarity solutions which correspond to, or predict, the typical coarsening process.

  12. Effect of annealing atmosphere on the thermal coarsening of nanoporous gold films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, A.Y.; Shi, S.S.; Liu, F. [School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Wang, Y. [Information Center, Second Military Medical University, Shanghai 200433 (China); Li, X. [School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Gu, J.F. [School of Materials Science & Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China); Xie, X.F., E-mail: xxfshcn@163.com [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-11-15

    Graphical abstract: SEM images of the NPG films annealed at different atmospheres for 2 h. (a–c) Annealed at 200, 300, and 400 °C in O{sub 2}, respectively; (d–f) annealed at 300, 400, and 500 °C in Ar, respectively; (g–i) annealed at 400, 500, and 600 °C in CO, respectively. All SEM images have the same scale bar. - Highlights: • The annealing atmosphere controls the coarsening of nanoporous gold (NPG). • The structure evolutions of NPG annealed in different atmospheres were studied. • The desorption of O{sub 2} induces a rapid coarsening of NPG above 200 °C. • The NPG can be stabilized high up to 600 °C in reductive CO gas. • The adsorbed CO onto the NPG surface can inhibit pore growth. - Abstract: The coarsening of nanoporous gold (NPG) is significantly influenced by surface adsorbates at elevated temperature. In this paper, the effect of annealing atmosphere on the thermal growth of the porous structure was investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. The NPG films were annealed in oxidative (air), inert (Ar) and reductive (CO) atmospheres at 100–600 °C for 2 h, respectively. The experimental results indicate that the NPG films show the best stability in the reductive atmosphere and the worst thermal properties in oxidative air. The NPG films annealed in air exhibit a significant pore growth at 200 °C and lose the porous structure at 300 °C, while those annealed in CO gas at 600 °C still remain the porous network. The thermal-induced coarsening of NPG films in air can be attributed to the desorption of O{sub 2} from the NPG surface above 200 °C. In contrast, the stabilization of the NPG films in CO gas originates from the strong binding of CO with Au atoms to form a complex adsorption layer, which effectively inhibits the surface diffusion of Au atoms.

  13. Curvature-driven coarsening in the two-dimensional Potts model.

    Science.gov (United States)

    Loureiro, Marcos P O; Arenzon, Jeferson J; Cugliandolo, Leticia F; Sicilia, Alberto

    2010-02-01

    We study the geometric properties of polymixtures after a sudden quench in temperature. We mimic these systems with the q -states Potts model on a square lattice with and without weak quenched disorder, and their evolution with Monte Carlo simulations with nonconserved order parameter. We analyze the distribution of hull-enclosed areas for different initial conditions and compare our results with recent exact and numerical findings for q=2 (Ising) case. Our results demonstrate the memory of the presence or absence of long-range correlations in the initial state during the coarsening regime and exhibit superuniversality properties.

  14. Coarsening Behavior and Plastic Flow of Ti-6Al-2Sn-4Zr-2Mo-0.1Si with an Ultrafine Microstructure

    Science.gov (United States)

    Semiatin, S. L.; Sun, F.; Crist, E. M.; Yu, K. O.; Sargent, G. A.; Sanders, D. G.

    2016-09-01

    Coarsening behavior and superplastic-flow response of Ti-6Al-2Sn-4Zr-2Mo-0.1Si with an ultrafine, equiaxed-alpha microstructure were interpreted in the context of classical models. Static coarsening was shown to follow modified Lifshitz-Slyosov-Wagner (LSW) kinetics. The rate of dynamic coarsening was six times more rapid than the corresponding static rate due to enhanced diffusion of solutes in the beta matrix. Last, a generalized constitutive equation was used to interpret the dependence of flow stress on strain/dynamic coarsening, strain rate, and temperature.

  15. Vanishing magnetic mass in QED$_{3}$ with a Chern-Simons term

    OpenAIRE

    Das, Ashok; Perez, Silvana

    2002-01-01

    We show that, at one loop, the magnetic mass vanishes at finite temperature in QED in any dimension. In QED$_{3}$, even the zero temperature part can be regularized to zero. We calculate the two loop contributions to the magnetic mass in QED$_{3}$ with a Chern-Simons term and show that it vanishes. We give a simple proof which shows that the magnetic mass vanishes to all orders at finite temperature in this theory. This proof also holds for QED in any dimension.

  16. Coarsening behavior of MX carbonitrides in type 347H heat-resistant austenitic steel during thermal aging

    Science.gov (United States)

    Zhou, Ying-hui; Liu, Chen-xi; Liu, Yong-chang; Guo, Qian-ying; Li, Hui-jun

    2016-03-01

    In this work, the growth kinetics of MX (M = metal, X = C/N) nanoprecipitates in type 347H austenitic steel was systematically studied. To investigate the coarsening behavior and the growth mechanism of MX carbonitrides during long-term aging, experiments were performed at 700, 800, 850, and 900°C for different periods (1, 24, 70, and 100 h). The precipitation behavior of carbonitrides in specimens subjected to various aging conditions was explored using carbon replicas and transmission electron microscopy (TEM) observations. The corresponding sizes of MX carbonitrides were measured. The results demonstrates that MX carbonitrides precipitate in type 347H austenitic steel as Nb(C,N). The coarsening rate constant is time-independent; however, an increase in aging temperature results in an increase in coarsening rate of Nb(C,N). The coarsening process was analyzed according to the calculated diffusion activation energy of Nb(C,N). When the aging temperature was 800-900°C, the mean activation energy was 294 kJ·mol-1, and the coarsening behavior was controlled primarily by the diffusion of Nb atoms.

  17. 雪花膏的制备%Vanishing Cream Preparation

    Institute of Scientific and Technical Information of China (English)

    陈战

    2012-01-01

    雪花膏是一种白色谢状乳剂类化妆品。作为一种不油腻、涂膜在皮肤上很快消失的,具有很好的保湿护肤品,深受广大爱美女性,甚至男性的喜爱。20世纪三四十年代,城市的街头到处都能看见雅霜的广告。雅霜是中国最早有规模生产的化妆品之一,俗称“雪花膏”.产地上海,并由上海“大陆药房”总经销。旧日的广告上,印着当时的当红明星白杨,甜心一般的笑容.胸前一束鲜化,那扮相让当时的女人心向往之。广告上说它是“最为爱美仕女之妆台良伴”。因此,庞大的需求量使得制备雪花膏的企业越来越多。在一般人看来,这些化妆品只能在商场或者网络上买到,其实,它的制备是很简单的,从原料到制作工艺,都是可以自己买到材料和手工制作完成的。%Vanishing cream is a white cream emulsion cosmetics. As a non-greasy coating on the skin disappear quickly, has good moisturizing skin care products, the majority of the beauty of women, and even men's favorite. Three to four decades of the 20th century, the streets of the city can be seen everywhere elegant cream ad. Ya cream is one of the earliest-scale production of cosmetics, commonly known as the" cream" Origin Shanghai, by the total distribution of the Shanghai continent pharmacy". Advertising on the old, printed star of Poplar, sweetheart generally smile chest a bouquet of flowers, so that the appearance of a woman at the time yearn. The ad said it was the "most beauty-conscious ladies' dressing table companion. Theretbre, the huge demand for the preparation cream business more and more. In the eyes of most people, these cosmetics can only be bought in the stores or on the network, in fact, it is very simple preparation, from raw materials to the production process, are can buy materials and handmade completed.

  18. Bubble statistics and coarsening dynamics for quasi-two-dimensional foams with increasing liquid content.

    Science.gov (United States)

    Roth, A E; Jones, C D; Durian, D J

    2013-04-01

    We report on the statistics of bubble size, topology, and shape and on their role in the coarsening dynamics for foams consisting of bubbles compressed between two parallel plates. The design of the sample cell permits control of the liquid content, through a constant pressure condition set by the height of the foam above a liquid reservoir. We find that in the scaling regime, all bubble distributions are independent not only of time, but also of liquid content. For coarsening, the average rate decreases with liquid content due to the blocking of gas diffusion by Plateau borders inflated with liquid; we achieve a factor of 4 reduction from the dry limit. By observing the growth rate of individual bubbles, we find that von Neumann's law becomes progressively violated with increasing wetness and decreasing bubble size. We successfully model this behavior by explicitly incorporating the border-blocking effect into the von Neumann argument. Two dimensionless bubble shape parameters naturally arise, one of which is primarily responsible for the violation of von Neumann's law for foams that are not perfectly dry.

  19. Characterization of Discontinuous Coarsening Reaction Products in INCONEL® Alloy 740H® Fusion Welds

    Science.gov (United States)

    Bechetti, Daniel H.; Dupont, John N.; Watanabe, Masashi; de Barbadillo, John J.

    2017-04-01

    Characterization of γ' coarsened zones (CZs) in alloy 740H fusion welds via a variety of electron microscopy techniques was conducted. The effects of solute partitioning during nonequilibrium solidification on the amount of strengthening precipitates along the grain boundaries were evaluated via electron-probe microanalysis and scanning electron microscopy. Electron backscatter diffraction was used to present evidence for the preferential growth of CZs toward regions of lower γ' content, even if growth in that direction increases grain boundary area. Scanning electron microscopy and image analysis were used to quantify the propensity for CZs to develop along certain segments of the grain boundaries, as governed by the local variations in γ' content. Scanning transmission electron microscopy with X-ray energy-dispersive spectrometry (XEDS) was used to assess the compositions of the matrix and precipitate phases within the CZs and to quantify the segregation of alloying components to the reaction front. Thermodynamic and kinetic modeling were used to compare calculated and experimental compositions. The work presented here provides new insight into the progression of the discontinuous coarsening (DC) reaction in a complex engineering alloy.

  20. Dynamic Coarsening of 3.3C-1.9Si Gray Cast Iron

    Science.gov (United States)

    Lora, Ruben; Diószegi, Attila

    2012-12-01

    The dynamic coarsening of primary austenite has been investigated by means of interrupted solidification in a hypoeutectic gray cast iron at three different cooling rates. The fundamental characteristic of the coarsening phenomenon, which is the reduction of the total interfacial area ( i.e., the primary austenite surface) over time, has been investigated along the solidification interval for the first time in gray cast iron. The primary austenite surface is confirmed to decrease with increasing solidification time. The relation between primary austenite surface reduction and the secondary dendrite arm spacing is reported as well as the time dependence of the inverse surface area of the primary phase per unit volume. The primary austenite surface has been determined via a stereological approach. The secondary dendrite arm spacing is observed to increase throughout the whole solidification range. A novel stereological relation, the modulus of primary dendrite, has been implemented on the calculation of the primary austenite surface. The size scale of the interdendritic phase has been determined by the hydraulic diameter of the interdendritic phase. The linear relations between secondary arm spacing and eutectic cells size and between secondary arm spacing and solidification time have been found to exist during solidification independently of cooling rate. The cooling rate dependence of the secondary dendrite arm spacing and the eutectic cells size is confirmed.

  1. Characterization of Discontinuous Coarsening Reaction Products in INCONEL® Alloy 740H® Fusion Welds

    Science.gov (United States)

    Bechetti, Daniel H.; Dupont, John N.; Watanabe, Masashi; de Barbadillo, John J.

    2017-02-01

    Characterization of γ' coarsened zones (CZs) in alloy 740H fusion welds via a variety of electron microscopy techniques was conducted. The effects of solute partitioning during nonequilibrium solidification on the amount of strengthening precipitates along the grain boundaries were evaluated via electron-probe microanalysis and scanning electron microscopy. Electron backscatter diffraction was used to present evidence for the preferential growth of CZs toward regions of lower γ' content, even if growth in that direction increases grain boundary area. Scanning electron microscopy and image analysis were used to quantify the propensity for CZs to develop along certain segments of the grain boundaries, as governed by the local variations in γ' content. Scanning transmission electron microscopy with X-ray energy-dispersive spectrometry (XEDS) was used to assess the compositions of the matrix and precipitate phases within the CZs and to quantify the segregation of alloying components to the reaction front. Thermodynamic and kinetic modeling were used to compare calculated and experimental compositions. The work presented here provides new insight into the progression of the discontinuous coarsening (DC) reaction in a complex engineering alloy.

  2. Serum inhibin B values in boys with unilateral vanished testis or unilateral cryptorchidism

    DEFF Research Database (Denmark)

    Thorup, Jorgen; Kvist, Kolja; Clasen-Linde, Erik

    2015-01-01

    differed between boys with unilateral vanished testis and those with unilateral cryptorchidism. MATERIALS AND METHODS: Blood samples from 297 boys 1.5 to 5 years old were included, of whom 222 had unilateral cryptorchidism, 29 had unilateral vanished testis and 46 had undergone unilateral orchiopexy 1 year...... previously. Serum inhibin B levels were measured using a commercially available ELISA kit and were compared to normal range. RESULTS: Serum inhibin B levels in boys with unilateral vanished testis were not different from those with unilateral cryptorchidism. Serum inhibin B values were above the normal...... median in 43% of boys previously operated on for unilateral cryptorchidism, compared to 17% at surgery (p = 0.0003). The percentage of patients with inhibin B levels below normal range was 14% in those with unilateral vanished testis, 23% in those with unilateral cryptorchidism and 11% in those who had...

  3. Foliations on the moduli space of curves, vanishing in cohomology, and Calogero-Moser curves

    CERN Document Server

    Grushevsky, Samuel

    2011-01-01

    Using meromorphic differentials with real periods, we show that a certain tautological homology class on the moduli space of smooth algebraic curves of genus g vanishes. The vanishing of the entire tautological ring for degree g-1 and higher, part of Faber's conjecture, is known in both homology and Chow --- it was proven by Looijenga, Ionel, and Graber-Vakil, and the class that we show vanishes is just one such tautological class. However, our approach, motivated by the Whitham perturbation theory of soliton equations, is completely new, elementary in the sense that no techniques beyond elementary complex analysis are used, and also leads to a natural non-speciality conjecture, which would imply many more vanishing results and relations among tautological classes. In the course of the proof we define and study foliations of the moduli space of curves constructed using periods of meromorphic differentials, in a way providing for meromorphic differentials a theory similar to that developed for abelian differen...

  4. Vanishing Str M2 in the presence of anomalous U A(1)

    Science.gov (United States)

    Lopez, Jorge L.; Nanopoulos, D. V.

    1996-02-01

    We show that the presence of an anomalous U A(1) factor in the gauge group of string-derived models may have the new and important phenomenological consequence of allowing the vanishing of Str M2 in the “shifted” vacuum that results in the process of cancelling the anomalous U A(1). The feasibility of this effect seems to be enhanced by a vanishing vacuum energy, and by a “small” value of Str M2 in the original vacuum. In the class of free-fermionic models with vanishing vacuum energy that we focus on, a necessary condition for this mechanism to be effective is that Str M2 > 0 in the original vacuum. A vanishing Str M2 ameliorates the cosmological constant problem and is a necessary element in the stability of the no-scale mechanism.

  5. The vanishing twin: a major determinant of infant outcome in IVF singleton births

    DEFF Research Database (Denmark)

    Pinborg, Anja; Lidegaard, Ojvind; Andersen, Anders Nyboe

    2006-01-01

    This article attempts to assess the frequency of vanishing twins in assisted reproductive and spontaneously conceived pregnancies, including in-vitro fertilization (IVF), and its impact on the live-born surviving twin....

  6. Delta Shocks and Vacuum States in Vanishing Pressure Limits of Solutions to the Relativistic Euler Equations

    Institute of Scientific and Technical Information of China (English)

    Gan YIN; Wancheng SHENG

    2008-01-01

    The Riemann problems for the Euler system of conservation laws of energy and momentum in special relativity as pressure vanishes are considered. The Riemann solutions for the pressureless relativistic Euler equations are obtained constructively. There are two kinds of solutions, the one involves delta shock wave and the other involves vacuum. The authors prove that these two kinds of solutions are the limits of the solutions as pressure vanishes in the Euler system of conservation laws of energy and momentum in special relativity.

  7. Strong generic vanishing and a higher-dimensional Castelnuovo–de Franchis inequality

    OpenAIRE

    Pareschi, Giuseppe; Popa, Mihnea

    2009-01-01

    We extend to manifolds of arbitrary dimension the Castelnuovo-de Franchis inequality for surfaces. The proof is based on the theory of Generic Vanishing and higher regularity, and on the Evans-Griffith Syzygy Theorem in commutative algebra. Along the way we give a positive answer, in the setting of K\\"ahler manifolds, to a question of Green-Lazarsfeld on the vanishing of higher direct images of Poincar\\'e bundles. We indicate generalizations to arbitrary Fourier-Mukai transforms.

  8. The vanishing twin: a major determinant of infant outcome in IVF singleton births

    DEFF Research Database (Denmark)

    Pinborg, Anja; Lidegaard, Ojvind; Andersen, Anders Nyboe

    2006-01-01

    This article attempts to assess the frequency of vanishing twins in assisted reproductive and spontaneously conceived pregnancies, including in-vitro fertilization (IVF), and its impact on the live-born surviving twin.......This article attempts to assess the frequency of vanishing twins in assisted reproductive and spontaneously conceived pregnancies, including in-vitro fertilization (IVF), and its impact on the live-born surviving twin....

  9. Gender Dynamics in Science and Technology :From the "Leaky Pipeline" to the "Vanish Box"

    OpenAIRE

    Etzkowitz, Henry; Ranga, Marina

    2011-01-01

    This paper discusses the “Vanish Box phenomenon” found among female scientists who migrate from academia to new occupations emerging at the intersection between science and business, like technology transfer. These occupations offer not only new career paths, but also more favourable work conditions in comparison to academic science and industrial research. The ‘Vanish Box’ refers to women scientists’ recoupment, rather than loss, through their reinsertion into an alternative context in which...

  10. Lattice QCD at non-vanishing density phase diagram, equation of state

    CERN Document Server

    Csikor, Ferenc; Fodor, Z; Katz, S D; Szabó, K K; Tóth, A I

    2003-01-01

    We propose a method to study lattice QCD at non-vanishing temperature (T) and chemical potential (\\mu). We use n_f=2+1 dynamical staggered quarks with semi-realistic masses on L_t=4 lattices. The critical endpoint (E) of QCD on the Re(\\mu)-T plane is located. We calculate the pressure (p), the energy density (\\epsilon) and the baryon density (n_B) of QCD at non-vanishing T and \\mu.

  11. Nonlinear approximation with redundant dictionaries

    DEFF Research Database (Denmark)

    Borup, Lasse; Nielsen, M.; Gribonval, R.

    2005-01-01

    In this paper we study nonlinear approximation and data representation with redundant function dictionaries. In particular, approximation with redundant wavelet bi-frame systems is studied in detail. Several results for orthonormal wavelets are generalized to the redundant case. In general......, for a wavelet bi-frame system the approximation properties are limited by the number of vanishing moments of the system. In some cases this can be overcome by oversampling, but at a price of replacing the canonical expansion by another linear expansion. Moreover, for special non-oversampled wavelet bi-frames we...... can obtain good approximation properties not restricted by the number of vanishing moments, but again without using the canonical expansion....

  12. Adaptive remeshing method in 2D based on refinement and coarsening techniques

    Science.gov (United States)

    Giraud-Moreau, L.; Borouchaki, H.; Cherouat, A.

    2007-04-01

    The analysis of mechanical structures using the Finite Element Method, in the framework of large elastoplastic strains, needs frequent remeshing of the deformed domain during computation. Remeshing is necessary for two main reasons, the large geometric distortion of finite elements and the adaptation of the mesh size to the physical behavior of the solution. This paper presents an adaptive remeshing method to remesh a mechanical structure in two dimensions subjected to large elastoplastic deformations with damage. The proposed remeshing technique includes adaptive refinement and coarsening procedures, based on geometrical and physical criteria. The proposed method has been integrated in a computational environment using the ABAQUS solver. Numerical examples show the efficiency of the proposed approach.

  13. Survival curve estimation for informatively coarsened discrete event-time data.

    Science.gov (United States)

    Shardell, Michelle; Scharfstein, Daniel O; Bozzette, Samuel A

    2007-05-10

    Interval-censored, or more generally, coarsened event-time data arise when study participants are observed at irregular time periods and experience the event of interest in between study observations. Such data are often analysed assuming non-informative censoring, which can produce biased results if the assumption is wrong. This paper extends the standard approach for estimating survivor functions to allow informatively interval-censored data by incorporating various assumptions about the censoring mechanism into the model. We include a Bayesian extension in which final estimates are produced by mixing over a distribution of assumed censoring mechanisms. We illustrate these methods with a natural history study of HIV-infected individuals using assumptions elicited from an AIDS expert.

  14. Thermodynamic coarsening arrested by viscous fingering in partially miscible binary mixtures

    Science.gov (United States)

    Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

    2016-09-01

    We study the evolution of binary mixtures far from equilibrium, and show that the interplay between phase separation and hydrodynamic instability can arrest the Ostwald ripening process characteristic of nonflowing mixtures. We describe a model binary system in a Hele-Shaw cell using a phase-field approach with explicit dependence of both phase fraction and mass concentration. When the viscosity contrast between phases is large (as is the case for gas and liquid phases), an imposed background flow leads to viscous fingering, phase branching, and pinch off. This dynamic flow disorder limits phase growth and arrests thermodynamic coarsening. As a result, the system reaches a regime of statistical steady state in which the binary mixture is permanently driven away from equilibrium.

  15. Effect of cold rolling and first precipitates on the coarsening behavior of γ″-phases in Inconel 718 alloy

    Science.gov (United States)

    Zhang, Jing-ling; Guo, Qian-ying; Liu, Yong-chang; Li, Chong; Yu, Li-ming; Li, Hui-jun

    2016-09-01

    The coarsening behaviors of γ″-phase particles in Inconel 718 alloy aged at 750, 800, and 850°C were investigated by scanning electron microscopy (SEM). Detailed observations and quantitative measurements were conducted to characterize the coarsening behavior of the γ?-phase under various aging conditions. The experimental results indicate that the existence of the δ-phase retards the formation and coarsening of the γ″-phase, without influencing its final particle size or amount. Moreover, when cold rolled with a reduction of 50%, the dimensions of the γ″ particles in Inconel 718 alloy decrease with increasing aging time. Furthermore, the coarsening behavior of the γ″-phase in the Inconel 718 alloy after a normal aging treatment (sample A) and that of the primary δ-phase (sample B) follow the Lifshitz-Slyozov-Wagner (LSW) diffusion-controlled growth theory; the thus-obtained activation energies for the γ″-phase are 292 kJ·mol-1 and 302 kJ·mol-1, respectively.

  16. A Novel Line Space Voting Method for Vanishing-Point Detection of General Road Images

    Directory of Open Access Journals (Sweden)

    Zongsheng Wu

    2016-06-01

    Full Text Available Vanishing-point detection is an important component for the visual navigation system of an autonomous mobile robot. In this paper, we present a novel line space voting method for fast vanishing-point detection. First, the line segments are detected from the road image by the line segment detector (LSD method according to the pixel’s gradient and texture orientation computed by the Sobel operator. Then, the vanishing-point of the road is voted on by considering the points of the lines and their neighborhood spaces with weighting methods. Our algorithm is simple, fast, and easy to implement with high accuracy. It has been experimentally tested with over hundreds of structured and unstructured road images. The experimental results indicate that the proposed method is effective and can meet the real-time requirements of navigation for autonomous mobile robots and unmanned ground vehicles.

  17. A Novel Line Space Voting Method for Vanishing-Point Detection of General Road Images.

    Science.gov (United States)

    Wu, Zongsheng; Fu, Weiping; Xue, Ru; Wang, Wen

    2016-06-23

    Vanishing-point detection is an important component for the visual navigation system of an autonomous mobile robot. In this paper, we present a novel line space voting method for fast vanishing-point detection. First, the line segments are detected from the road image by the line segment detector (LSD) method according to the pixel's gradient and texture orientation computed by the Sobel operator. Then, the vanishing-point of the road is voted on by considering the points of the lines and their neighborhood spaces with weighting methods. Our algorithm is simple, fast, and easy to implement with high accuracy. It has been experimentally tested with over hundreds of structured and unstructured road images. The experimental results indicate that the proposed method is effective and can meet the real-time requirements of navigation for autonomous mobile robots and unmanned ground vehicles.

  18. So It Vanished: Art, Taboo and Shared Space in Contemporary Aotearoa New Zealand

    Directory of Open Access Journals (Sweden)

    Jonathan Barrett

    2013-04-01

    Full Text Available In February 2012, The Dowse Art Museum in Lower Hutt, near Wellington, planned to host So It Vanishes, an exhibition by acclaimed Mexican artist Teresa Margolles, whose often shocking works seek to highlight how dispensable human life has become in the parts of Mexico riven by drugs wars. Margolles’s installation would have used infinitesimal amounts of morgue water in a bubble mixture dispensed into an empty, silent room in the same building that sacred Māori treasures are housed. The incorporation of water used to wash corpses in So It Vanishes, particularly in proximity to cultural treasures, would have been deeply offensive, indeed dangerous, for Māori people. Following objections, the exhibition was cancelled. This article analyses the cancellation of So It Vanishes and seeks to answer whether and how transgressive art and indigenous beliefs may be reconciled in contemporary Aotearoa New Zealand.

  19. A Novel Line Space Voting Method for Vanishing-Point Detection of General Road Images

    Science.gov (United States)

    Wu, Zongsheng; Fu, Weiping; Xue, Ru; Wang, Wen

    2016-01-01

    Vanishing-point detection is an important component for the visual navigation system of an autonomous mobile robot. In this paper, we present a novel line space voting method for fast vanishing-point detection. First, the line segments are detected from the road image by the line segment detector (LSD) method according to the pixel’s gradient and texture orientation computed by the Sobel operator. Then, the vanishing-point of the road is voted on by considering the points of the lines and their neighborhood spaces with weighting methods. Our algorithm is simple, fast, and easy to implement with high accuracy. It has been experimentally tested with over hundreds of structured and unstructured road images. The experimental results indicate that the proposed method is effective and can meet the real-time requirements of navigation for autonomous mobile robots and unmanned ground vehicles. PMID:27347947

  20. Non-vanishing of Taylor coefficients and Poincaré series

    DEFF Research Database (Denmark)

    O'Sullivan, C.; Risager, Morten S.

    2013-01-01

    We prove recursive formulas for the Taylor coefficients of cusp forms, such as Ramanujan's Delta function, at points in the upper half-plane. This allows us to show the non-vanishing of all Taylor coefficients of Delta at CM points of small discriminant as well as the non-vanishing of certain...... Poincaré series. At a "generic" point, all Taylor coefficients are shown to be non-zero. Some conjectures on the Taylor coefficients of Delta at CM points are stated. © 2012 Springer Science+Business Media, LLC....

  1. Variational Iteration Method for Volterra Functional Integrodifferential Equations with Vanishing Linear Delays

    Directory of Open Access Journals (Sweden)

    Ali Konuralp

    2014-01-01

    Full Text Available Application process of variational iteration method is presented in order to solve the Volterra functional integrodifferential equations which have multi terms and vanishing delays where the delay function θ(t vanishes inside the integral limits such that θ(t=qt for 0

  2. Amenability and vanishing of L^2-Betti numbers: an operator algebraic approach

    CERN Document Server

    Alekseev, Vadim

    2011-01-01

    We recast the Foelner condition in an operator algebraic setting and prove that it implies a certain dimension flatness property. Furthermore, it is proven that the Foelner condition generalizes the existing notions of amenability and that the enveloping von Neumann algebra arising from a Foelner algebra is automatically injective. As an application we show how our techniques unify the previously known results concerning vanishing of L^2-Betti numbers for amenable groups, groupoids and quantum groups and moreover provides a large class of new examples of algebras with vanishing L^2-Betti numbers.

  3. $(k,s)$-positivity and vanishing theorems for compact Kahler manifolds

    CERN Document Server

    Yang, Qi-Lin

    2010-01-01

    We study the $(k,s)$-positivity for holomorphic vector bundles on compact complex manifolds. $(0,s)$-positivity is exactly the Demailly $s$-positivity and a $(k,1)$-positive line bundle is just a $k$-positive line bundle in the sense of Sommese. In this way we get a unified theory for all kinds of positivities used for semipositive vector bundles. Several new vanishing theorems for $(k,s)$-positive vector bundles are proved and the vanishing theorems for $k$-ample vector bundles on projective algebraic manifolds are generalized to $k$-positive vector bundles on compact K\\"ahler manifolds.

  4. Testing and Inference in Nonlinear Cointegrating Vector Error Correction Models

    DEFF Research Database (Denmark)

    Kristensen, Dennis; Rahbæk, Anders

    for linearity is of particular interest as parameters of non-linear components vanish under the null. To solve the latter type of testing, we use the so-called sup tests, which here requires development of new (uniform) weak convergence results. These results are potentially useful in general for analysis...

  5. Testing and inference in nonlinear cointegrating vector error correction models

    DEFF Research Database (Denmark)

    Kristensen, D.; Rahbek, A.

    2013-01-01

    the null of linearity, parameters of nonlinear components vanish, leading to a nonstandard testing problem. We apply so-called sup-tests to resolve this issue, which requires development of new(uniform) functional central limit theory and results for convergence of stochastic integrals. We provide a full...

  6. Gravity Effects in Diffusive Coarsening of Bubble Lattices: von Neumann's Law

    Science.gov (United States)

    Noever, David A.

    2000-01-01

    von Neumann modelled the evolution of two-dimensional soap froths as a purely diffusive phenomenon; the area growth of a given cell was found to depend only on the geometry of the bubble lattice. In the model, hexagons are stable, pentagons shrink and heptagons grow. The simplest equivalent to the area growth law is / approximately t(sub beta). The result depends on assuming (1) an incompressible gas; (2) bubble walls which meet at 120 deg and (3) constant wall thickness and curvature. Each assumption is borne out in experiments except the last one: bubble wall thickness between connecting cells varies in unit gravity because of gravity drainage. The bottom part of the soap membrane is thickened, the top part is thinned, such that gas diffusion across the membrane shows a complex dependence on gravity. As a result, experimental tests of von Neumann's law have been influenced by effects of gravity; fluid behavior along cell borders can give non-uniform wall thicknesses and thus alter the effective area and gas diffusion rates between adjacent bubbles. For area plotted as a function of time, Glazier (J.A. Glazier, S.P. Gross, and I. Stavans, Phys. Rev. A. 36, 306 (1987); J. Stavans, J.A, Glazier, Phys. Rev. Lett. 62, 1318 (1989).) suggest that in some cases their failure to observe von Neumann's predicted growth exponent ((sup beta)theor(sup =1; beta)exp(sup =0.70 + 0.10)) may have been the result of such "fluid drainage onto the lower glass plate". Additional experiments which varied plate spacing gave different beta exponents in a fashion consistent with this suggestion. During preliminary long duration experiments (approximately 100 h) aboard Spacelab-J, a low-gravity test of froth coarsening has examined (1) power law scaling of von Neumann's law (beta values) in the appropriate diffusive limits; (2) new bubble lattice dynamics such as greater fluid wetting behavior on froth membranes in low gravity; and (3) explicit relations for the gravity dependence of the

  7. Local invariants vanishing on stationary horizons: a diagnostic for locating black holes.

    Science.gov (United States)

    Page, Don N; Shoom, Andrey A

    2015-04-10

    Inspired by the example of Abdelqader and Lake for the Kerr metric, we construct local scalar polynomial curvature invariants that vanish on the horizon of any stationary black hole: the squared norms of the wedge products of n linearly independent gradients of scalar polynomial curvature invariants, where n is the local cohomogeneity of the spacetime.

  8. The Vanishing West: 1964-2010--The Disappearance of Western Civilization from the American Undergraduate Curriculum

    Science.gov (United States)

    Ricketts, Glenn; Wood, Peter R.; Balch, Stephen H.; Thorne, Ashley

    2011-01-01

    "The Vanishing West" traces the decline and near extinction of the Western Civilization history survey course in America's top colleges and universities from 1964 to 2010. This course, covering classical antiquity to the present, was once part of the undergraduate curriculum's intellectual bedrock, not only because it was often a graduation…

  9. Boundary uniqueness theorems for functions whose integrals over hyperbolic discs vanish

    Energy Technology Data Exchange (ETDEWEB)

    Ochakovskaya, Oksana A [Institute of Applied Mathematics and Mechanics, National Academy of Sciences of Ukraine, Donetsk (Ukraine)

    2013-02-28

    Sharp conditions are found describing the admissible rate of decrease of a nontrivial function whose integrals over all hyperbolic discs with fixed radius vanish. For the first time, the boundary behaviour of the function is investigated in a neighbourhood of a single point on the boundary of the domain of definition. Bibliography: 17 titles.

  10. Optimized Voting Scheme for Efficient Vanishing Point Detection in General Road Images

    Directory of Open Access Journals (Sweden)

    Vipul H. Mistry

    2016-08-01

    Full Text Available Next generation automobile industries are aiming for development of vision-based driver assistance system and driver-less vehicle system. In the context of this application, a major challenge lies in the identification of efficient road region segmentation from captured image frames. Recent research work suggests that use of a global feature like vanishing point makes the road detection algorithm more robust and general for all types of roads. The goal of this research work is the reduction of computational complexity involved with voting process for identification of vanishing point. This paper presents an efficient and optimized voter selection strategy to identify vanishing point in general road images. The major outcome of this algorithm is the reduction in computational complexity as well as improvement in efficiency of vanishing point detection algorithm for all types of road images. The key attributes of the methodology are dominant orientation selection, voter selection based on voter location and modified voting scheme, combining dominant orientation and distance based soft voting process. Results of a number of qualitative and quantitative experiments clearly demonstrate the efficiency of proposed algorithm.

  11. Optimization of Fast-Decodable Full-Rate STBC with Non-Vanishing Determinants

    CERN Document Server

    Ren, Tian Peng; Yuen, Chau; Zhou, Yue; Zhang, Er Yang

    2011-01-01

    Full-rate STBC (space-time block codes) with non-vanishing determinants achieve the optimal diversity-multiplexing tradeoff but incur high decoding complexity. To permit fast decoding, Sezginer, Sari and Biglieri proposed an STBC structure with special QR decomposition characteristics. In this paper, we adopt a simplified form of this fast-decodable code structure and present a new way to optimize the code analytically. We show that the signal constellation topology (such as QAM, APSK, or PSK) has a critical impact on the existence of non-vanishing determinants of the full-rate STBC. In particular, we show for the first time that, in order for APSK-STBC to achieve non-vanishing determinant, an APSK constellation topology with constellation points lying on square grid and ring radius $\\sqrt{m^2+n^2} (m,n\\emph{\\emph{integers}})$ needs to be used. For signal constellations with vanishing determinants, we present a methodology to analytically optimize the full-rate STBC at specific constellation dimension.

  12. Deformation quantization of a Kaehler-Poisson structure vanishing on a Levi nondegenerate hypersurface

    OpenAIRE

    Karabegov, Alexander V.

    2006-01-01

    We give an elementary proof of the result by Leichtnam, Tang, and Weinstein that there exists a deformation quantization with separation of variables on a complex manifold endowed with a Kaehler-Poisson structure vanishing on a Levi nondegenerate hypersurface and nondegenerate on its complement.

  13. Nonlinear Quantum Optics in Optomechanical Nanoscale Waveguides

    CERN Document Server

    Zoubi, Hashem

    2016-01-01

    We explore the possibility of achieving a significant nonlinear phase shift among photons propagating in nanoscale waveguides exploiting interactions among photons that are mediated by vibrational modes and induced through Stimulated Brillouin Scattering (SBS). We introduce a configuration that allows slowing down the photons by several orders of magnitude via SBS involving sound waves and two pump fields. We extract the conditions for maintaining vanishing amplitude gain or loss for slowly propagating photons while keeping the influence of thermal phonons to the minimum. The nonlinear phase among two counter-propagating photons can be used to realize a deterministic phase gate.

  14. Measuring laves phase particle size and thermodynamic calculating its growth and coarsening behavior in P92 steels

    DEFF Research Database (Denmark)

    Yao, Bing-Yin; Zhou, Rong-Can; Fan, Chang-Xin;

    2010-01-01

    ) images in scanning electron microscope (SEM). The smaller Laves phase particle size results in higher creep strength and longer creep exposure time at the same conditions. DICTRA software was used to model the growth and coarsening behavior of Laves phase in the three P92 steels. Good agreements were......The growth of Laves phase particles in three kinds of P92 steels were investigated. Laves phase particles can be easily separated and distinguished from the matrix and other particles by atom number contrast using comparisons of the backscatter electrons (BSE) images and the secondary electrons (SE...... attained between measurements in SEM and modeling by DICTRA. Ostwald ripening should be used for the coarsening calculation of Laves phase in P92 steels for time longer than 20000 h and 50000 h at 650°C and 600°C, respectively. © 2010 Chin. Soc. for Elec. Eng....

  15. Deaths from heart failure: using coarsened exact matching to correct cause-of-death statistics

    Directory of Open Access Journals (Sweden)

    Shibuya Kenji

    2010-04-01

    Full Text Available Abstract Background Incomplete information on death certificates makes recorded cause-of-death data less useful for public health monitoring and planning. Certifying physicians sometimes list only the mode of death without indicating the underlying disease or diseases that led to the death. Inconsistent cause-of-death assignment among cardiovascular causes of death is of particular concern. This can prevent valid epidemiologic comparisons across countries and over time. Methods We propose that coarsened exact matching be used to infer the underlying causes of death where only the mode of death is known. We focus on the case of heart failure in US, Mexican, and Brazilian death records. Results Redistribution algorithms derived using this method assign the largest proportion of heart failure deaths to ischemic heart disease in all three countries (53%, 26%, and 22% respectively, with larger proportions assigned to hypertensive heart disease and diabetes in Mexico and Brazil (16% and 23% vs. 7% for hypertensive heart disease, and 13% and 9% vs. 6% for diabetes. Reassigning these heart failure deaths increases the US ischemic heart disease mortality rate by 6%. Conclusions The frequency with which physicians list heart failure in the causal chain for various underlying causes of death allows for inference about how physicians use heart failure on the death certificate in different settings. This easy-to-use method has the potential to reduce bias and increase comparability in cause-of-death data, thereby improving the public health utility of death records.

  16. Orientation-field models for polycrystalline solidification: Grain coarsening and complex growth forms

    Science.gov (United States)

    Korbuly, Bálint; Pusztai, Tamás; Tóth, Gyula I.; Henry, Hervé; Plapp, Mathis; Gránásy, László

    2017-01-01

    We compare two versions of the phase-field theory for polycrystalline solidification, both relying on the concept of orientation fields: one by Kobayashi et al. [Physica D 140 (2000) 141] [15] and the other by Henry et al. [Phys. Rev. B 86 (2012) 054117] [22]. Setting the model parameters so that the grain boundary energies and the time scale of grain growth are comparable in the two models, we first study the grain coarsening process including the limiting grain size distribution, and compare the results to those from experiments on thin films, to the models of Hillert, and Mullins, and to predictions by multiphase-field theories. Next, following earlier work by Gránásy et al. [Phys. Rev. Lett. 88 (2002) 206105; Phys. Rev. E 72 (2005) 011605] [17,21], we extend the orientation field to the liquid state, where the orientation field is made to fluctuate in time and space, and employ the model for describing of multi-dendritic solidification, and polycrystalline growth, including the formation of "dizzy" dendrites disordered via the interaction with foreign particles.

  17. The coarsening effect of SA508-3 steel used as heavy forgings material

    Directory of Open Access Journals (Sweden)

    Dingqian Dong

    2015-01-01

    Full Text Available SA508Gr.3 steel is popularly used to produce core unit of nuclear power reactors due to its outstanding ability of anti-neutron irradiation and good fracture toughness. The forging process takes important role in manufacturing to refine the grain size and improve the material properties. But due to their huge size, heavy forgings cannot be cooled down quickly, and the refined grains usually have long time to grow in high temperature conditions. If the forging process is not adequately scheduled or implemented, very large grains up to millimetres in size may be found in this steel and cannot be eliminated in the subsequent heat treatment. To fix the condition which may causes the coarsening of the steel, hot upsetting experiments in the industrial production environment were performed under different working conditions and the corresponding grain sizes were measured and analysed. The observation showed that the grain will abnormally grow if the deformation is less than a critical value. The strain energy takes a critical role in the grain evolution. If dynamic recrystallization consumes the strain energy as much as possible, the normal grains will be obtained. While if not, the stored strain energy will promote abnormal growth of the grains.

  18. Study of phase decomposition and coarsening of γ′ precipitates in Ni-12 at.% Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Garay-Reyes, C.G., E-mail: garay_820123@hotmail.com [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra leona 550, Col. Lomas 2 sección, 78210 S.L.P. (Mexico); Hernández-Santiago, F. [Instituto Politécnico Nacional, ESIME-AZC, Av. de las Granjas 682, col. Sta. Catarina, 02550 D.F. (Mexico); Cayetano-Castro, N. [Instituto Potosino de Investigación Científica y Tecnológica, División de Materiales Avanzados, camino a la Presa San José 2055, Col Lomas 4 sección, 78216 S.L.P. (Mexico); López-Hirata, V.M. [Instituto Politécnico Nacional, ESIQIE-DIM, 118-556, D.F. (Mexico); García-Rocha, J. [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra leona 550, Col. Lomas 2 sección, 78210 S.L.P. (Mexico); Hernández-Rivera, J.L. [Centro de Investigación de Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua (Mexico); Dorantes-Rosales, H.J. [Instituto Politécnico Nacional, ESIQIE-DIM, 118-556, D.F. (Mexico); Cruz-Rivera, J.J. [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra leona 550, Col. Lomas 2 sección, 78210 S.L.P. (Mexico)

    2013-09-15

    The early stages of phase decomposition, morphological evolution of precipitates, coarsening kinetics of γ′ precipitates and micro-hardness in Ni-12 at.% Ti alloy are studied by transmission electron microscopy (TEM) and Vickers hardness tests (VHN). Disk-shaped specimens are solution treated at 1473 K (1200 °C) and aged at 823, 923 and 1023 K (550, 650 and 750 °C) during several periods of time. TEM results show that a conditional spinodal of order occurs at the beginning of the phase decomposition and exhibit the following decomposition sequence and morphological evolution of precipitates: α{sub sss} → γ″ irregular–cuboidal + γ{sub s} → γ′ cuboidal–parallelepiped + γ → η plates + γ. In general during the coarsening of γ′ precipitates, the experimental coarsening kinetics do not fit well to the LSW or TIDC (n = 2.281) theoretical models, however the activation energies determined using the TIDC and LSW theories (262.846 and 283.6075 kJ mol{sup −1}, respectively) are consistent with previously reported values. The highest hardness obtained at 823, 923 and 1023 K (550, 650 and 750 °C) is associated with the presence of γ′ precipitates. - Highlights: • It was studied the conditional spinodal during early stages of phase decomposition. • It was obtained decomposition sequence and morphological evolution of precipitates. • It was experimentally evaluated the coarsening kinetics of γ′ precipitates. • The maximum hardness is associated with the γ′ precipitates.

  19. Vanishing Volcano

    Institute of Scientific and Technical Information of China (English)

    杨树仁

    1995-01-01

    Mauna Loa, the world’s largest active volcano,is sinking into the Pacific Ocean——and it’s taking the main island of Hawaii with it! The problem:The mighty volcano has gained too much weight, says Peter Lipman of the U. S. Geological Survey.

  20. Dynamics of condensate formation in stochastic transport with pair-factorized steady states: Nucleation and coarsening time scales

    Science.gov (United States)

    Nagel, Hannes; Janke, Wolfhard

    2016-05-01

    Driven diffusive systems such as the zero-range process (ZRP) and the pair-factorized steady states (PFSS) stochastic transport process are versatile tools that lend themselves to the study of transport phenomena on a generic level. While their mathematical structure is simple enough to allow significant analytical treatment, they offer a variety of interesting phenomena. With appropriate dynamics, the ZRP and PFSS models feature a condensation transition where, for a supercritical density, the translational symmetry breaks spontaneously and excess particles form a single-site or spatially extended condensate, respectively. In this paper we numerically study the typical time scales of the two stages of this condensation process: Nucleation and coarsening. Nucleation is the first stage of condensation where the bulk system relaxes to its stationary distribution and droplet nuclei form in the system. These droplets then gradually grow or evaporate in the coarsening regime to coalesce in a single condensate when the system finally relaxes to the stationary state. We use the ZRP condensation model to discuss the choice of the estimation method for the nucleation time scale and present scaling exponents for the ZRP and PFSS condensation models with respect to the choice of the typical droplet nuclei mass. We then proceed to present scaling exponents in the coarsening regime of the ZRP for partially asymmetric dynamics and the PFSS model for symmetric and asymmetric dynamics.

  1. Interfacial Dislocation Networks and Creep in Directional Coarsened Ru-Containing Nickel-Base Single-Crystal Superalloys

    Science.gov (United States)

    Carroll, L. J.; Feng, Q.; Pollock, T. M.

    2008-06-01

    Mechanisms of creep deformation in nickel-base superalloy single crystals in the directional coarsening regime have been studied in alloys with large variations in γ- γ' lattice misfit and phase composition, achieved by Ru additions and variable levels of Cr and Co. Interfacial dislocation spacings established by long-term annealing experiments under no externally applied stress indicate that the experimental alloys have high-temperature lattice misfits ranging from near-zero to as large as -0.65 pct. Variation in misfit influences the stress-induced directional coarsening (rafting) behavior during creep deformation at 950 °C and 290 MPa. In postcreep deformed material, the density of excess dislocations (defined as the dislocations beyond those necessary to relieve the lattice misfit) at the γ- γ' interfaces varied with alloy composition, with the most creep-resistant alloy containing the highest excess interfacial dislocation density. In the directional coarsening creep regime, continued deformation requires shearing of the γ' rafts and is strongly influenced by the resistance of the precipitates to shearing as well as the interfacial dislocation structure. A preliminary model for creep in the rafting regime is developed.

  2. A Novel Martensitic Creep-Resistant Steel Strengthened by MX Carbonitrides with Extremely Low Coarsening Rates: Design and Characterization

    Science.gov (United States)

    Lu, Qi; Ma, Wenjie; Yan, Wei; Yang, Ke; Toda, Yoshiaki; van der Zwaag, Sybrand; Xu, Wei

    2016-09-01

    A general computational alloy design approach, based on thermodynamics and thermokinetics and coupled with a genetic algorithm optimization routine, was applied to the design of novel creep martensitic resistant steels. The optimal alloy suggested by the model has a high density of barely coarsening MX carbonitride precipitates. The model yielded precise values for the concentrations of the 10 alloying elements considered. The model alloy was produced on a 10 kg lab scale. Samples of the new alloy of one of the best commercial martensitic steels on the market P92 were subjected to a high aging temperature of 923 K (650 °C) for times up to 1000 hours. The microstructure of the new alloy in the as-produced state as well as after 1000 hours exposure has all the intended features as predicted by the model. The coarsening rate of the MX rate carbonitrides was substantially lower than that of the precipitates in the P92 steel. The very low coarsening rate explains the superior hardness at very long exposure times.

  3. Spectral properties of a confined nonlinear quantum oscillator in one and three dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Schulze-Halberg, Axel; Gordon, Christopher R. [Department of Mathematics and Actuarial Science, Indiana University Northwest, 3400 Broadway, Gary, Indiana 46408 (United States)

    2013-04-15

    We analyze the spectral behaviour of a nonlinear quantum oscillator model under confinement. The underlying potential is given by a harmonic oscillator interaction plus a nonlinear term that can be weakened or strengthened through a parameter. Numerical eigenvalues of the model in one and three dimensions are presented. The asymptotic behaviour of the eigenvalues for confinement relaxation and for vanishing nonlinear term in the potential is investigated. Our findings are compared with existing results.

  4. Grain coarsening in two-dimensional phase-field models with an orientation field

    Science.gov (United States)

    Korbuly, Bálint; Pusztai, Tamás; Henry, Hervé; Plapp, Mathis; Apel, Markus; Gránásy, László

    2017-05-01

    In the literature, contradictory results have been published regarding the form of the limiting (long-time) grain size distribution (LGSD) that characterizes the late stage grain coarsening in two-dimensional and quasi-two-dimensional polycrystalline systems. While experiments and the phase-field crystal (PFC) model (a simple dynamical density functional theory) indicate a log-normal distribution, other works including theoretical studies based on conventional phase-field simulations that rely on coarse grained fields, like the multi-phase-field (MPF) and orientation field (OF) models, yield significantly different distributions. In a recent work, we have shown that the coarse grained phase-field models (whether MPF or OF) yield very similar limiting size distributions that seem to differ from the theoretical predictions. Herein, we revisit this problem, and demonstrate in the case of OF models [R. Kobayashi, J. A. Warren, and W. C. Carter, Physica D 140, 141 (2000), 10.1016/S0167-2789(00)00023-3; H. Henry, J. Mellenthin, and M. Plapp, Phys. Rev. B 86, 054117 (2012), 10.1103/PhysRevB.86.054117] that an insufficient resolution of the small angle grain boundaries leads to a log-normal distribution close to those seen in the experiments and the molecular scale PFC simulations. Our paper indicates, furthermore, that the LGSD is critically sensitive to the details of the evaluation process, and raises the possibility that the differences among the LGSD results from different sources may originate from differences in the detection of small angle grain boundaries.

  5. Quark-hadron phase structure and QCD equations of state in vanishing and finite magnetic field

    CERN Document Server

    Tawfik, Abdel Nasser; Hussein, M T

    2016-01-01

    In characterizing the quark-hadron phase structure, determining various thermodynamic quantities and investigating their temperature dependencies on vanishing and finite magnetic field, SU(3) Polyakov linear-sigma model (PLSM) is utilized. The dependence of the chiral order-parameter on vanishing and finite magnetic field is calculated in mean-field approximation. In a wide range of temperatures and magnetic field strengths, the thermodynamic observables including trace anomaly, speed of sound squared, entropy density, specific heat and magnetization are presented. An excellent agreement is found when these are confronted to recent lattice QCD calculations. The temperature dependence of these quantities confirms our previous result that the transition temperature is reduced with magnetic field. Furthermore, the temperature dependence of magnetization verifies the conclusion that the QCD matter has paramagnetic properties near and far above the critical temperature. The excellent agreement with recent lattice ...

  6. On the Vanishing of the CP Asymmetry in Leptogenesis due to Form Dominance

    CERN Document Server

    Choubey, Sandhya; Mitra, Manimala

    2010-01-01

    We emphasize that the vanishing of the CP asymmetry in leptogenesis, previously observed for models with tri-bimaximal mixing and family symmetry, may be traced to a property of the type I see-saw mechanism satisfied by such models known as Form Dominance, corresponding to the case of a diagonal Casas-Ibarra R-matrix. Form Dominance leads to vanishing flavour-dependent CP asymmetries irrespective of whether one has tri-bimaximal mixing or a family symmetry. Successful leptogenesis requires violation of Form Dominance, but not necessarily violation of tri bimaximal mixing. This may be achieved in models where the family symmetry responsible for tri-bimaximal mixing is implemented indirectly and a strong neutrino mass hierarchy is present with the Form Dominance broken only softly by the right-handed neutrino responsible for the lightest neutrino mass, as in constrained sequential dominance.

  7. Quad-Rotor Helicopter Autonomous Navigation Based on Vanishing Point Algorithm

    Directory of Open Access Journals (Sweden)

    Jialiang Wang

    2014-01-01

    Full Text Available Quad-rotor helicopter is becoming popular increasingly as they can well implement many flight missions in more challenging environments, with lower risk of damaging itself and its surroundings. They are employed in many applications, from military operations to civilian tasks. Quad-rotor helicopter autonomous navigation based on the vanishing point fast estimation (VPFE algorithm using clustering principle is implemented in this paper. For images collected by the camera of quad-rotor helicopter, the system executes the process of preprocessing of image, deleting noise interference, edge extracting using Canny operator, and extracting straight lines by randomized hough transformation (RHT method. Then system obtains the position of vanishing point and regards it as destination point and finally controls the autonomous navigation of the quad-rotor helicopter by continuous modification according to the calculated navigation error. The experimental results show that the quad-rotor helicopter can implement the destination navigation well in the indoor environment.

  8. THE VANISHING PRESSURE LIMIT OF SOLUTIONS TO THE SIMPLIFIED EULER EQUATIONS FOR ISENTROPIC FLUIDS

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In this paper,the Riemann problem of the 1-D reduced model for the 2-D Euler equations is considered and the Riemann solutions are obtained.It is proved that,as the pressure vanishes,they converge to two kinds of Riemann solutions to the 1D reduced model for the 2-D transport equations:one contains δ-shocks,the other contains vacuum.

  9. Long Time Evolution of Populations under Selection and Vanishing Mutations

    KAUST Repository

    Raoul, Gaël

    2011-02-08

    In this paper, we consider a long time and vanishing mutations limit of an integro-differential model describing the evolution of a population structured with respect to a continuous phenotypic trait. We show that the asymptotic population is a steady-state of the evolution equation without mutations, and satisfies an evolutionary stability condition. © 2011 Springer Science+Business Media B.V.

  10. Vanishing bile duct syndrome in human immunodeficiency virus: Nevirapine hepatotoxicity revisited

    Institute of Scientific and Technical Information of China (English)

    Rajan; Kochar; Moises; I; Nevah; Frank; J; Lukens; Michael; B; Fallon; Victor; I; Machicao

    2010-01-01

    Vanishing bile duct syndrome (VBDS) refers to a group of disorders characterized by prolonged cholestasis as a result of destruction and disappearance ofintrahepatic bile ducts. Multiple etiologies have been indentifi ed including infections, neoplastic disorders, autoimmune conditions and drugs. The natural history of this condition is variable and may involve resolution of cholestasis or progression with irreversible damage. VBDS is extremely rare in human immunodeficiency virus (HIV)-infected patients an...

  11. A Vanishing Result for Donaldson Thomas Invariants of P1 Scroll

    Institute of Scientific and Technical Information of China (English)

    Huai Liang CHANG

    2014-01-01

    Let S be a smooth algebraic surface and let L be a line bundle on S. Suppose there is a holomorphic two form over S with zero loci to be a curve C. We show that the Donaldson-Thomas invariant of the P1 scroll X =P (L⊕OS ) vanishes unless the curves being enumerated lie in D=P (L|C⊕OC ). Our method is cosection localization of Y.-H. Kiem and J. Li.

  12. Spreading and vanishing in the diffusive prey-predator model with a free boundary

    Science.gov (United States)

    Wang, Mingxin

    2015-06-01

    This paper deals with the diffusive Lotka-Volterra type prey-predator model with a free boundary over a one dimensional habitat. This problem may be used to describe the interaction between indigenous species and invasive species and the spreading of such two species, with the free boundary representing the expanding front. Our main purpose is to study the spreading and vanishing phenomena and long time behaviors of prey and predator.

  13. Phase-vanishing method with acetylene evolution and its utilization in several organic syntheses.

    Science.gov (United States)

    Matake, Ryosuke; Niwa, Yuki; Matsubara, Hiroshi

    2015-05-15

    A novel quadraphasic phase-vanishing system in which acetylene is evolved from calcium carbide and directly applied in situ to the Sonogashira coupling reaction was developed. This method, which provides a safe, convenient, and one-pot means to utilize gaseous reagents without special equipment, was also applied to a Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and a three-component aldehyde-alkyne-amine (A(3)) coupling reaction with excellent results.

  14. BETWEEN APPARITION AND VANISHING: AESTHETIC THRESHOLDS IN THE WORK OF OSCAR MUÑOZ

    OpenAIRE

    Flor Ángel Rincón Muñoz

    2014-01-01

    This article intends a reading of the artistic production of the Colombian artist Óscar Muñoz (1951). For so doing, we start from his early works -and from a psychoanalytic perspective- to focus on the analysis of apparitionand vanishing, concepts which are undertaken chiefly from the viewpoint of Martin Seel (1954) and Paul Virilio (1932). In this way, an alternative reading of the aesthetic and significant processes found in the works of Muñoz is proposed.

  15. New limits on neutrino magnetic moment through non-vanishing 13-mixing

    CERN Document Server

    Guzzo, Marcelo Moraes; Peres, Orlando Luis Goulart

    2012-01-01

    The relatively large value of neutrino mixing angle \\theta_{13} set by recent measurements allows us to use solar neutrinos to set a limit on neutrino magnetic moment involving second and third families, \\mu_{\\mu\\tau}. The existence of a random magnetic field in solar convective zone can produce a significant anti-neutrino flux when a non-vanishing neutrino magnetic moment is assumed. Even if we consider a vanishing neutrino magnetic moment involving the first family, electron anti-neutrinos are indirectly produced through the mixing between first and third families and non-vanishing \\mu_{\\mu\\tau}. Using KamLAND limits on the solar flux of electron anti-neutrino, we set the limit \\mu_{\\mu\\tau} < 0.5e-11 Bohr magneton for a reasonable assumption on the behavior of solar magnetic fields. This is the first time a limit on \\mu_{\\mu\\tau} is established in the literature and, interestingly enough, is comparable with the limits on neutrino magnetic moment involving the first neutrino family.

  16. Photonic gap vanishing in one-dimensional photonic crystals with single-negative metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yihang, E-mail: kallenmail@sina.com [Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Laboratory of Quantum Information Technology, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou (China); Wang, Yu; Leung, C.W.; Hu, Mingzhe; Chan, H.L.W. [Department of Applied Physics, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China)

    2011-06-13

    The properties of photonic band gap in one-dimensional photonic crystals composed of single-negative metamaterials are studied theoretically. Our study shows that the photonic gap will vanish at a certain incident angle when both the phase-match and impedance-match conditions are satisfied simultaneously, suggesting that the bandwidth and location of the photonic gap are strongly dependent on the incident angle and polarization. However, the photonic gap will not vanish and may become insensitive to the incident angle when the two match conditions cannot be met. Our study also shows that losses in metamaterials have little effect on the properties of the photonic gap. -- Highlights: → Photonic gap of 1D photonic crystal containing metamaterials was investigated. → The gap can be designed to be sensitive or insensitive to the incident angle. → The gap can be designed to be close at a specific incident angle. → Conditions for photonic gap vanishing were proposed. → Losses of metamaterials have little effect on the properties of the photonic gap.

  17. The Vanishing Ball Illusion: A new perspective on the perception of dynamic events.

    Science.gov (United States)

    Kuhn, Gustav; Rensink, Ronald A

    2016-03-01

    Our perceptual experience is largely based on prediction, and as such can be influenced by knowledge of forthcoming events. This susceptibility is commonly exploited by magicians. In the Vanishing Ball Illusion, for example, a magician tosses a ball in the air a few times and then pretends to throw the ball again, whilst secretly concealing it in his hand. Most people claim to see the ball moving upwards and then vanishing, even though it did not leave the magician's hand (Kuhn & Land, 2006; Triplett, 1900). But what exactly can such illusions tell us? We investigated here whether seeing a real action before the pretend one was necessary for the Vanishing Ball Illusion. Participants either saw a real action immediately before the fake one, or only a fake action. Nearly one third of participants experienced the illusion with the fake action alone, while seeing the real action beforehand enhanced this effect even further. Our results therefore suggest that perceptual experience relies both on long-term knowledge of what an action should look like, as well as exemplars from the immediate past. In addition, whilst there was a forward displacement of perceived location in perceptual experience, this was not found for oculomotor responses, consistent with the proposal that two separate systems are involved in visual perception.

  18. Solvable Groups, Free Divisors and Nonisolated Matrix Singularities II: Vanishing Topology

    CERN Document Server

    Damon, James

    2012-01-01

    In this paper we use the results from the first part to compute the vanishing topology for matrix singularities based on certain spaces of matrices. We place the variety of singular matrices in a geometric configuration of free divisors which are the "exceptional orbit varieties" for repesentations of solvable groups. Because there are towers of representations for towers of solvable groups, the free divisors actually form a tower of free divisors $E_n$, and we give an inductive procedure for computing the vanishing topology of the matrix singularities. The inductive procedure we use is an extension of that introduced by L\\^{e}-Greuel for computing the Milnor number of an ICIS. Instead of linear subspaces, we use free divisors arising from the geometric configuration and which correspond to subgroups of the solvable groups. Here the vanishing topology involves a singular version of the Milnor fiber; however, it still has the good connectivity properties and is homotopy equivalent to a bouquet of spheres, whos...

  19. Rapidly vanishing lung pseudotumor in a patient with acute bilateral bronchopneumonia

    Directory of Open Access Journals (Sweden)

    Lazović Biljana

    2013-01-01

    Full Text Available Introduction. Rapidly vanishing lung pseudotumor (phantom tumor refers to the transient well-demarcated accumulation of pleural fluid in the interlobar pulmonary fissures. Most frequently their appearance is associated with congestive heart failure, but also other disorders like hypoalbuminemia, renal insufficiency or pleuritis. Its rapid disappearance in response to the treatment of the underlying disorder is a classical feature of this clinical entity. Case report. A 47-yearold woman, chronic smoker with symptoms of shortness of breath, orthopnea, chills, cough, weakness and the temperature of 39.2°C was admitted to our hospital. A posteroanterior chest X-ray revealed cardiomegaly with the cardiothoracic ratio of > 0.5, blunting of both costophrenic angles and an adjacent 6 x 5 cm well-defined, rounded opacity in the right interlobar fissure. Transthoracic 2-dimensional echocardiography demonstrated left ventricular hyperthrophy with a systolic ejection fraction of 25% and moderate mitral regurgitation. The patient’s symptoms resolved rapidly after diuresis, and repeated chest X-ray four days later showed that the right lung opacity and pleural effusions had vanished. Conclusion. The presented case underlines the importance of the possibility of vanishing lung tumor in patients with left ventricular failure and a sharp oval lung mass on the chest X-ray. This is the way to avoid incorrect interpretation of this finding causing additional, unnecessary, costly or invasive imaging, interventions and drugs.

  20. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  1. Nonlinear supratransmission

    Energy Technology Data Exchange (ETDEWEB)

    Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)

    2003-05-07

    A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.

  2. Simulation study of directional coarsening (rafting) of gamma' in single crystal nickel-aluminum

    Science.gov (United States)

    Zhou, Ning

    Dislocation propagation in and work hardening of gamma channels and directional coarsening (rafting) of gamma' precipitates are the major microscopic processes taking place during high temperature deformation of single crystal Ni-base superalloys. Understanding of those processes is crucial for developing improved models of creep and fatigue of turbine blades in aircraft engines. Recent investigations of rafting in superalloys demonstrate clearly the importance of elastic modulus difference between the gamma and gamma' phases and dislocation-level activities in the gamma-channels in determining the kinetic pathway of the processes. The elastic modulus difference can lead to the non-uniform distribution of stresses through the interaction with the lattice misfit and external load. While work hardening in the gamma channels has a direct effect on differentiation of the stress state in the vertical and horizontal channels and on gamma/gamma' interface coherency and energy, and hence influences the diffusive flow and morphological changes of the gamma/gamma' microstructure. In turn, changes in particle shape and coherency of the interface alter the local stress state and thereby the Peach-Koehler force on dislocations. Although existing models treating these processes separately can offer a qualitative explanation about the direction of rafting for typical superalloys, a complete quantitative understanding of rafting phenomena requires these processes to be treated simultaneously in a common framework because of their intimate coupling. The objective of this thesis is to develop an integrated computational approach in simulating simultaneous evolution of both gamma/gamma' microstructure and dislocations in an elastically anisotropic and inhomogeneous system by using a single, consistent phase field methodology. In particular, the phase field dislocation model is used to simulate the initial dislocation gamma channel filling process and calculate stress distribution

  3. Mathematical Modeling of the Growth and Coarsening of Ice Particles in the Context of High Pressure Shift Freezing Processes

    KAUST Repository

    Smith, N. A. S.

    2013-07-25

    High pressure shift freezing (HPSF) has been proven more beneficial for ice crystal size and shape than traditional (at atmospheric pressure) freezing.1-3 A model for growth and coarsening of ice crystals inside a frozen food sample (either at atmospheric or high pressure) is developed, and some numerical experiments are given, with which the model is validated by using experimental data. To the best of our knowledge, this is the first model suited for freezing crystallization in the context of high pressure. © 2013 American Chemical Society.

  4. Weyl geometry and the nonlinear mechanics of distributed point defects

    KAUST Repository

    Yavari, A.

    2012-09-05

    The residual stress field of a nonlinear elastic solid with a spherically symmetric distribution of point defects is obtained explicitly using methods from differential geometry. The material manifold of a solid with distributed point defects-where the body is stress-free-is a flat Weyl manifold, i.e. a manifold with an affine connection that has non-metricity with vanishing traceless part, but both its torsion and curvature tensors vanish. Given a spherically symmetric point defect distribution, we construct its Weyl material manifold using the method of Cartan\\'s moving frames. Having the material manifold, the anelasticity problem is transformed to a nonlinear elasticity problem and reduces the problem of computing the residual stresses to finding an embedding into the Euclidean ambient space. In the case of incompressible neo-Hookean solids, we calculate explicitly this residual stress field. We consider the example of a finite ball and a point defect distribution uniform in a smaller ball and vanishing elsewhere. We show that the residual stress field inside the smaller ball is uniform and hydrostatic. We also prove a nonlinear analogue of Eshelby\\'s celebrated inclusion problem for a spherical inclusion in an isotropic incompressible nonlinear solid. © 2012 The Royal Society.

  5. Nonlinear (Super)Symmetries and Amplitudes

    CERN Document Server

    Kallosh, Renata

    2016-01-01

    There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the generalized background field method we show how, in general, nonlinear symmetries of the action, bosonic and fermionic, constrain amplitudes beyond soft limits. The same identities control, for example, bosonic E_{7(7)} scalar sector symmetries as well as the fermionic goldstino symmetries. We present a universal derivation of the vanishing amplitudes in the single (bosonic or fermionic) soft limit. We explain why, universally, the double-soft limit probes the coset space algebra. We also provide identities describing the multiple-soft limit. We discuss loop corrections to N\\geq 5 supergravity, to the D3 brane, and the UV completion of constrained multiplets in string theory.

  6. Azimuthal correlation functions and the energy of vanishing flow in nucleus-nucleus collisions

    Energy Technology Data Exchange (ETDEWEB)

    Angelique, J.C.; Bizard, G.; Brou, R.; Cussol, D.; Kerambrun, A.; Patry, J.P.; Peter, J.; Regimbart, R.; Steckmeyer, J.C.; Tamain, B.; Vient, E. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Buta, A.; Popescu, R. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire]|[Central Inst. of Physics, Bucharest (Romania). Inst. of Physics and Nuclear Engineering; Auger, G.; Cabot, C.; Peghaire, A.; Saint-Laurent, F. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Cassagnou, Y.; Legrain, R. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; El Masri, Y. [Universite Catholique de Louvain (UCL), Louvain-la-Neuve (Belgium); Eudes, P.; Lebrun, C. [Nantes Univ., 44 (France). Lab. de Physique Nucleaire; Gonin, M.; Hagel, K.; Wada, R. [Texas A and M Univ., College Station, TX (United States). Cyclotron Inst.; Rosato, E. [Istituto Nazionale di Fisica Nucleare, Naples (Italy); He, Z.Y. [Lanzhou Univ., GS (China). Dept. of Modern Physics; Crema, E. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)]|[Sao Paulo Univ., SP (Brazil). Inst. de Fisica

    1994-06-01

    A novel method is proposed for studying the evolution of flow phenomena with the incident energy, and for quantitatively estimating the energy of vanishing flow (also called balance energy, E{sub bal}) without reconstructing the reaction plane. We used a method based on the shapes of experimental particle-particle azimuthal correlation functions to determine E{sub bal} for three systems: Ar + Al, Zn + Ti, Zn + Ni. We compare the results with estimations using flow parameter analysis and also with theoretical expectations. (authors). 25 refs.

  7. Non-vanishing of L-functions, the Ramanujan conjecture, and families of Hecke characters

    CERN Document Server

    Blomer, Valentin

    2011-01-01

    We prove a non-vanishing result for families of $\\GL_n\\times\\GL_n$ Rankin-Selberg $L$-functions in the critical strip, as one factor runs over twists by Hecke characters. As an application, we simplify the proof, due to Luo, Rudnick, and Sarnak, of the best known bounds towards the Generalized Ramanujan Conjecture at the infinite places for cusp forms on $\\GL_n$. A key ingredient is the regularization of the units in residue classes by the use of an Arakelov ray class group.

  8. More on non-supersymmetric asymmetric orbifolds with vanishing cosmological constant

    Science.gov (United States)

    Sugawara, Yuji; Wada, Taiki

    2016-08-01

    We explore various non-supersymmetric type II string vacua constructed based on asymmetric orbifolds of tori with vanishing cosmological constant at the one loop. The string vacua we present are modifications of the models studied in [14], of which orbifold group is just generated by a single element. We especially focus on two types of modifications: (i) the orbifold twists include different types of chiral reflections not necessarily removing massless Rarita-Schwinger fields in the 4-dimensional space-time, (ii) the orbifold twists do not include the shift operator. We further discuss the unitarity and stability of constructed non-supersymmetric string vacua, with emphasizing the common features of them.

  9. Hamiltonian Formalism of mKdV Equation with Non-vanishing Boundary Values

    Institute of Scientific and Technical Information of China (English)

    HE Jing-Song; CHEN Shi-Rong

    2005-01-01

    Hamiltonian formalism of the mKdV equation with non-vanishing boundary valueis re-examined by a revised form of the standard procedure. It is known that the previous papers did not give the final results and involved some questionable points [T.C. Au Yeung and P.C.W. Fung, J. Phys. A 21 (1988) 3575]. In this note, simple results are obtained in terms of an affine parameter and a Galileo transformation is introduced to ensure the results compatible with those derived from the inverse scattering transform.

  10. Vanishing viscosity limits for the degenerate lake equations with Navier boundary conditions

    CERN Document Server

    Jiu, Quansen; Wu, Jiahong

    2011-01-01

    The paper is concerned with the vanishing viscosity limit of the two-dimensional degenerate viscous lake equations when the Navier slip conditions are prescribed on the impermeable boundary of a simply connected bounded regular domain. When the initial vorticity is in the Lebesgue space $L^q$ with $2

  11. a Unified Dark Energy Model from a Vanishing Speed of Sound with Emergent Cosmological Constant

    Science.gov (United States)

    Luongo, Orlando; Quevedo, Hernando

    2014-11-01

    The problem of the cosmic acceleration is here revisited by using the fact that the adiabatic speed of sound can be assumed to be negligible small. Within the context of general relativity, the total energy budget is recovered under the hypothesis of a vanishing speed of sound by assuming the existence of one fluid only. We find a cosmological model which reproduces the main results of the ΛCDM paradigm at late-times, showing an emergent cosmological constant, which is not at all related with the vacuum energy term. As a consequence, the model presented here behaves as a unified dark energy (DE) model.

  12. Vanishing bile duct and Stevens-Johnson syndrome associated with ciprofloxacin treated with tacrolimus

    Institute of Scientific and Technical Information of China (English)

    Gokhan Okan; Serpil Yaylaci; Onder Peker; Sabahattin Kaymakoglu; Murat Saruc

    2008-01-01

    Stevens-Johnson syndrome (SJS) is a serious and potentially life-threatening disease. Vanishing bile duct syndrome (VBDS) is a rare cause of progressive cholestasis. Both syndromes are mostly related with drugs. We report a case of a patient withciprofloxacin-induced SJS and acute onset of VBDS,and reviewed the related literature. It is the first case of ciprofloxacin-induced VBDS successfully treatedwith tacrolimus. This case reminds physicians of the importance of drug reactions, their severity, techniques for diagnosis and methods of management.

  13. Emergent Lorentz symmetry with vanishing velocity in a critical two-subband quantum wire.

    Science.gov (United States)

    Sitte, M; Rosch, A; Meyer, J S; Matveev, K A; Garst, M

    2009-05-01

    We consider a quantum wire with two subbands of spin-polarized electrons in the presence of strong interactions. We focus on the quantum phase transition when the second subband starts to get filled as a function of gate voltage. Performing a one-loop renormalization group analysis of the effective Hamiltonian, we identify the critical fixed-point theory as a conformal field theory having an enhanced SU(2) symmetry and central charge 3/2. While the fixed point is Lorentz invariant, the effective "speed of light" nevertheless vanishes at low energies due to marginally irrelevant operators leading to a diverging critical specific heat coefficient.

  14. Current work and open problems in the numerical analysis of Volterra functional equations with vanishing delays

    Institute of Scientific and Technical Information of China (English)

    Hermann BRUNNER

    2009-01-01

    The aims of this paper are (i) to present a survey of recent advances in the analysis of superconvergence of collocation solutions for linear Volterra-type functional integral and integro-differential equations with delay functions θ(t) vanishing at the initial point of the interval of integration (with θ(t) = qt (0 < q < 1,t ≥0) being an important special case),and (ii) to point,by means of a list of open problems,to areas in the numerical analysis of such Volterra functional equations where more research needs to be carried out.

  15. The parity-preserving massive QED3: Vanishing β-function and no parity anomaly

    Directory of Open Access Journals (Sweden)

    O.M. Del Cima

    2015-11-01

    Full Text Available The parity-preserving massive QED3 exhibits vanishing gauge coupling β-function and is parity and infrared anomaly free at all orders in perturbation theory. Parity is not an anomalous symmetry, even for the parity-preserving massive QED3, in spite of some claims about the possibility of a perturbative parity breakdown, called parity anomaly. The proof is done by using the algebraic renormalization method, which is independent of any regularization scheme, based on general theorems of perturbative quantum field theory.

  16. Near maximal atmospheric mixing in neutrino mass matrices with two vanishing minors

    Energy Technology Data Exchange (ETDEWEB)

    Dev, S., E-mail: dev5703@yahoo.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Gupta, Shivani, E-mail: shiroberts_1980@yahoo.co.in [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Gautam, Radha Raman, E-mail: gautamrrg@gmail.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Singh, Lal, E-mail: lalsingh96@yahoo.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India)

    2011-12-06

    In the flavor basis there are seven cases of two vanishing minors in the neutrino mass matrix which can accommodate the present neutrino oscillation data including the recent T2K data. It is found that two of these cases, namely B{sub 5} and B{sub 6} predict near maximal atmospheric neutrino mixing in the limit of large effective neutrino mass. This feature remains irrespective of the values of solar and reactor mixing angles. A non-zero reactor mixing angle is naturally accommodated in these textures.

  17. Leukcenccphalopathy with vanishing white matter%白质消融性白质脑病

    Institute of Scientific and Technical Information of China (English)

    吴晔

    2009-01-01

    自质消融性自质脑病(leukoencephalopathy with vanishing white matter,VWM)又称儿童共济失调伴中枢神经系统髓鞘化不良(childhood ataxia with central nervous system hypomyelination,CACH,OMIM306896),是一种常染色体隐性遗传的向质脑病,是儿童遗传性自质脑病中常见的类型之一,其患病率尚缺乏统计。

  18. Optimal hostage rescue problem where action can only be taken once : case where effect vanishes thereafter

    OpenAIRE

    Shi, Fengbo

    2001-01-01

    we propose the following model for optimal rescue problems concerning hostages. Suppose that a person is taken as a hostage and that a decision has to be made from among three alternatives: rescuing, no rescuing, or taking one action which will save the situation. It is assumed that the action can only be taken once and it will be effective only at that time, i.e., the effect vanishes thereafter. The objective here is to find the optimal decision rule so as to maximize the probability of the ...

  19. BETWEEN APPARITION AND VANISHING: AESTHETIC THRESHOLDS IN THE WORK OF OSCAR MUÑOZ

    Directory of Open Access Journals (Sweden)

    Flor Ángel Rincón Muñoz

    2014-05-01

    Full Text Available This article intends a reading of the artistic production of the Colombian artist Óscar Muñoz (1951. For so doing, we start from his early works -and from a psychoanalytic perspective- to focus on the analysis of apparitionand vanishing, concepts which are undertaken chiefly from the viewpoint of Martin Seel (1954 and Paul Virilio (1932. In this way, an alternative reading of the aesthetic and significant processes found in the works of Muñoz is proposed.

  20. Practical Nonlinearities

    Science.gov (United States)

    2016-07-01

    Advanced Research Projects Agency (DARPA) Dynamics-Enabled Frequency Sources (DEFYS) program is focused on the convergence of nonlinear dynamics and...Early work in this program has shown that nonlinear dynamics can provide performance advantages. However, the pathway from initial results to...dependent nonlinear stiffness observed in these devices. This work is ongoing, and will continue through the final period of this program . Reference 9

  1. Precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel

    Institute of Scientific and Technical Information of China (English)

    Lin-qing Xu; Dan-tian Zhang; Yong-chang Liu; Bao-qun Ning; Zhi-xia Qiao; Ze-sheng Yan; Hui-jun Li

    2014-01-01

    Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facili-tates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron mi-croscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the for-mation of M3C (cementite) precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides (MX) along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener’s equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro-structural evolution and hardness variation, the process of tempering can be separated into three steps.

  2. Precipitation behavior and martensite lath coarsening during tempering of T/P92 ferritic heat-resistant steel

    Science.gov (United States)

    Xu, Lin-qing; Zhang, Dan-tian; Liu, Yong-chang; Ning, Bao-qun; Qiao, Zhi-xia; Yan, Ze-sheng; Li, Hui-jun

    2014-05-01

    Tempering is an important process for T/P92 ferritic heat-resistant steel from the viewpoint of microstructure control, as it facilitates the formation of final tempered martensite under serving conditions. In this study, we have gained deeper insights on the mechanism underlying the microstructural evolution during tempering treatment, including the precipitation of carbides and the coarsening of martensite laths, as systematically analyzed by optical microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. The chemical composition of the precipitates was analyzed using energy dispersive X-ray spectroscopy. Results indicate the formation of M3C (cementite) precipitates under normalized conditions. However, they tend to dissolve within a short time of tempering, owing to their low thermal stability. This phenomenon was substantiated by X-ray diffraction analysis. Besides, we could observe the precipitation of fine carbonitrides (MX) along the dislocations. The mechanism of carbon diffusion controlled growth of M23C6 can be expressed by the Zener's equation. The movement of Y-junctions was determined to be the fundamental mechanism underlying the martensite lath coarsening process. Vickers hardness was estimated to determine their mechanical properties. Based on the comprehensive analysis of both the micro-structural evolution and hardness variation, the process of tempering can be separated into three steps.

  3. Nonlinear oscillations

    CERN Document Server

    Nayfeh, Ali Hasan

    1995-01-01

    Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim

  4. Nonlinear Science

    CERN Document Server

    Yoshida, Zensho

    2010-01-01

    This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl

  5. Nonlinear analysis

    CERN Document Server

    Nanda, Sudarsan

    2013-01-01

    "Nonlinear analysis" presents recent developments in calculus in Banach space, convex sets, convex functions, best approximation, fixed point theorems, nonlinear operators, variational inequality, complementary problem and semi-inner-product spaces. Nonlinear Analysis has become important and useful in the present days because many real world problems are nonlinear, nonconvex and nonsmooth in nature. Although basic concepts have been presented here but many results presented have not appeared in any book till now. The book could be used as a text for graduate students and also it will be useful for researchers working in this field.

  6. The effect of rare earth elements on the kinetics of the isothermal coarsening of the globular solid phase in semisolid AZ91 alloy produced via SIMA process

    Energy Technology Data Exchange (ETDEWEB)

    Nami, B. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Shabestari, S.G., E-mail: shabestari@iust.ac.i [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Miresmaeili, S.M. [Department of Mechanical Engineering, Shahid Radjaei University, Lavizan, Tehran (Iran, Islamic Republic of); Razavi, H.; Mirdamadi, Sh. [Department of Materials and Metallurgical Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of)

    2010-01-21

    In the present study, the effects of rare earth (RE) elements on the microstructure and coarsening kinetics of the solid globular particle in the semisolid slurry of AZ91 magnesium alloy have been studied at 570 {sup o}C and 580 {sup o}C. The results showed that the coarsening kinetics of the solid globular particles in semisolid slurry of AZ91 alloy satisfies the Ostwald ripening theory. It was shown that the coarsening rate of the solid particles decreases by adding RE elements into AZ91 alloy, specially at 580 {sup o}C, which results in the smaller particles size. It was attributed to the solid-liquid interfacial energy reduction due to the addition of RE elements.

  7. Vanishing Lung Syndrome in a Patient with HIV Infection and Heavy Marijuana Use

    Directory of Open Access Journals (Sweden)

    Basheer Tashtoush

    2014-01-01

    Full Text Available Vanishing lung syndrome (VLS is a rare and distinct clinical syndrome that usually affects young men. VLS leads to severe progressive dyspnea and is characterized by extensive, asymmetric, peripheral, and predominantly upper lobe giant lung bullae. Case reports have suggested an additive role of marijuana use in the development of this disease in young male tobacco smokers. We herein report a case of a 65-year-old Hispanic male previously diagnosed with severe emphysema and acquired immune deficiency syndrome (AIDS, with a history of intravenous heroin use and active marijuana smoking who presents to the emergency department with severe progressive shortness of breath he was found to have multiple large subpleural bullae occupying more than one-third of the hemithorax on chest computerized tomography (CT, characteristic of vanishing lung syndrome. The patient was mechanically ventilated and later developed a pneumothorax requiring chest tube placement and referral for surgical bullectomy. Surgical bullectomy has shown high success rates in alleviating the debilitating symptoms and preventing the life threatening complications of this rare syndrome. This case further emphasizes the importance of recognizing VLS in patients with severe emphysema and heavy marijuana smoking.

  8. Concentration in vanishing pressure limit of solutions to the modified Chaplygin gas equations

    Science.gov (United States)

    Yang, Hanchun; Wang, Jinhuan

    2016-11-01

    Two kinds of occurrence mechanism on the phenomenon of concentration and the formation of delta shock wave in vanishing pressure limit of solutions to the modified Chaplygin gas equations are analyzed and identified. The Riemann problem of the modified Chaplygin gas equations is first solved. Then it is shown that, as the pressure vanishes, any two-shock Riemann solution tends to a delta-shock solution to the transport equations, and the intermediate density between the two shocks tends to a weighted δ-measure which forms a delta shock wave; any two-rarefaction-wave Riemann solution tends to a two-contact-discontinuity solution to the transport equations, and the nonvacuum intermediate state in between tends to a vacuum state. It is also shown that, as the pressure approaches the generalized Chaplygin gas pressure, any two-shock Riemann solution tends to a delta-shock solution to the generalized Chaplygin gas equations. Some numerical results are presented to show the formation process of delta shock waves and vacuum states.

  9. Non-vanishing superpotentials in heterotic string theory and discrete torsion

    Science.gov (United States)

    Buchbinder, Evgeny I.; Ovrut, Burt A.

    2017-01-01

    We study the non-perturbative superpotential in E 8 × E 8 heterotic string theory on a non-simply connected Calabi-Yau manifold X, as well as on its simply connected covering space tilde{X} . The superpotential is induced by the string wrapping holomorphic, isolated, genus 0 curves. According to the residue theorem of Beasley and Witten, the non-perturbative superpotential must vanish in a large class of heterotic vacua because the contributions from curves in the same homology class cancel each other. We point out, however, that in certain cases the curves treated in the residue theorem as lying in the same homology class, can actually have different area with respect to the physical Kahler form and can be in different homology classes. In these cases, the residue theorem is not directly applicable and the structure of the superpotential is more subtle. We show, in a specific example, that the superpotential is non-zero both on tilde{X} and on X. On the non-simply connected manifold X, we explicitly compute the leading contribution to the superpotential from all holomorphic, isolated, genus 0 curves with minimal area. The reason for the non-vanishing of the superpotental on X is that the second homology class contains a finite part called discrete torsion. As a result, the curves with the same area are distributed among different torsion classes and, hence, do not cancel each other.

  10. THE "VANISHING TWIN" SYNDROME - A MYTH OR CLINICAL REALITY IN THE OBSTETRIC PRACTICE?

    Directory of Open Access Journals (Sweden)

    Emil Kovachev

    2015-09-01

    Full Text Available Background: A case of triplets pregnancy after IVF ET, ended with a spontaneous reduction of one of the fetuses. The patient was with secondary infertility, with two unsuccessful preceding IVF Procedures and reduced ovarian reserve. A short flare up protocol with recombinant FSH was performed and three embryos were transferred on day three. An intrauterine pregnancy and three gestational sacs with CA (cardiac activity were visualized via transvaginal ultrasonography by the twenty-first day. After the patient refused to go through an embrioreduction, during a routine sonography by the fourteenth week, the death of one fetus was reported. The pregnancy was finalized with the Cesarean delivery of two newborn in good health by thirty- seventh week. During the regular examination of the placentas, a mummified fetus -fetus papyraceus was found Objective: To report a case of "Vanishing Twin" syndrome. Design: Case report. Methods: Clinical presentation, examination and ultrasound were consistent with diagnosis “Vanishing Twin” syndrome. Conclusion: The frequency of multi fetal births considerably increased after ART.

  11. Anisotropic Friedmann-Robertson-Walker universe from nonlinear massive gravity

    CERN Document Server

    Gumrukcuoglu, A Emir; Mukohyama, Shinji

    2012-01-01

    In the scope of the nonlinear massive gravity, we study fixed points of evolution equations for a Bianchi type--I universe. We find a new attractor solution with non-vanishing anisotropy, on which the physical metric is isotropic but the Stuckelberg configuration is anisotropic. As a result, at the background level, the solution describes a homogeneous and isotropic universe, while a statistical anisotropy is expected from perturbations, suppressed by smallness of the graviton mass.

  12. A Solvable Model in Two-Dimensional Gravity Coupled to a Nonlinear Matter Field

    Institute of Scientific and Technical Information of China (English)

    YAN Jun; WANG Shun-Jin; TAO Bi-You

    2001-01-01

    The two-dimensional gravity model with a coupling constant k = 4 and a vanishing cosmological constant coupled to a nonlinear matter field is investigated. We found that the classical equations of motion are exactly solvable and the static solutions of the induced metric and scalar curvature can be obtained analytically. These solutions may be used to describe the naked singularity at the origin.``

  13. Proposal for detection of QED vacuum nonlinearities in Maxwell's equations by the use of waveguides.

    Science.gov (United States)

    Brodin, G; Marklund, M; Stenflo, L

    2001-10-22

    We present a novel method for detecting nonlinearities, due to quantum electrodynamics through photon-photon scattering, in Maxwell's equation. The photon-photon scattering gives rise to self-interaction terms which are similar to the nonlinearities due to the polarization in nonlinear optics. These self-interaction terms vanish in the limit of parallel propagating waves, but if, instead of parallel propagating waves, the modes generated in waveguides are used, there will be a nonzero total effect. Based on this idea, we calculate the nonlinear excitation of new modes and estimate the strength of this effect. Furthermore, we suggest a principal experimental setup.

  14. Image mosaic based on the camera self-calibration of combining two vanishing points and pure rotational motion

    Science.gov (United States)

    Duan, Shaoli; Zang, Huaping; Zhang, Xiaofang; Gong, Qiaoxia; Tian, Yongzhi; Wang, Junqiao; Liang, Erjun; Liu, Xiaomin; Zhao, Shujun

    2016-10-01

    Camera calibration is one of the indispensable processes to obtain 3D depth information from 2D images in the field of computer vision. Camera self-calibration is more convenient and flexible, especially in the application of large depth of fields, wide fields of view, and scene conversion, as well as other occasions like zooms. In this paper, two selfcalibration methods respectively based on two vanishing points and homography are studied, and finally realizing the image mosaic based on self-calibration of the camera purely rotating around optical center. The geometric characteristic of disappear points formed by two groups of orthogonal parallel lines is applied to self-calibration based on two vanishing points. By using the vectors' orthogonal properties of connection optical centers and the vanishing points, the constraint equations on the camera intrinsic parameters are established. By this method, four internal parameters of the camera can be solved though only four images taked from different viewpoints in a scene. Compared with the other selfcalibration based on homography, the method based on two vanishing points has more convenient calibration process and simple algorithm. To check the quality of the self-calibration, we create a spherical mosaic of the images that were used for the self-calibration based on homography. Compared with the experimental results of two methods respectively based on calibration plate and self-calibration method using machine vision software Halcon, the practicability and effectiveness of self-calibration respectively based on two vanishing points and homography is verified.

  15. Nonlinear Reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Pen, Ue-Li; Chen, Xuelei; Yu, Hao-Ran

    2016-01-01

    We present a direct approach to non-parametrically reconstruct the linear density field from an observed non-linear map. We solve for the unique displacement potential consistent with the non-linear density and positive definite coordinate transformation using a multigrid algorithm. We show that we recover the linear initial conditions up to $k\\sim 1\\ h/\\mathrm{Mpc}$ with minimal computational cost. This reconstruction approach generalizes the linear displacement theory to fully non-linear fields, potentially substantially expanding the BAO and RSD information content of dense large scale structure surveys, including for example SDSS main sample and 21cm intensity mapping.

  16. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  17. Effect of zirconium addition on the austenite grain coarsening behavior and mechanical properties of 900 Mpa low carbon bainite steel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The ultra-free bainitic microstructure of a 900 MPa low carbon bainitic Cu-Ni-Mo-B steel was obtained by a newly developed relaxation precipitation control (RPC) phase transformation processing.In a pan-cake like prior-anstenite grain,the microstructure consisted of lath bainite,a little of abnormal granular bainite,and acicular ferrite.The effect of zirconium carbonitrides on the austenite grain coarsening behavior was studied by transmission electron microscopy (TEM).The results show that,the lath is narrower with increasing cooling rate.The ratio of all kinds of bainitic microstructure is proper with the intermediate cooling rate;and Zr-containing precipitates distribute uniformly,which restrains austenite grain growing in heat-affected welding zone.

  18. LETTER TO THE EDITOR: Coarsening in the 1D Ising model evolving with Swendsen - Wang dynamics: an unusual scaling

    Science.gov (United States)

    Derrida, Bernard; Hakim, Vincent

    1996-12-01

    We consider a simple model of domain growth: the zero-temperature 1D Ising model evolving according to the Swendsen - Wang dynamics. We find that in the long-time limit, the pair correlation function scales with a characteristic length increasing as the square of the average domain size. In that limit, a few large domains occupy almost all the space with many small domains between them. In contrast to the usual picture of coarsening, the average domain size here is not a characteristic length of the growth problem. Instead, one finds a power-law distribution for the sizes of large domains with a cut-off at a length which grows as the square of the average size of the domains.

  19. More on Non-supersymmetric Asymmetric Orbifolds with Vanishing Cosmological Constant

    CERN Document Server

    Sugawara, Yuji

    2016-01-01

    We explore various non-supersymmetric type II string vacua constructed based on asymmetric orbifolds of tori with vanishing cosmological constant at the one loop. The string vacua we present are modifications of the models studied in arXiv:1512.05155[hep-th], of which orbifold group is just generated by a single element. We especially focus on two types of modifications: (i) the orbifold twists include different types of chiral reflections not necessarily removing massless Rarita-Schwinger fields in the 4-dimensional space-time, (ii) the orbifold twists do not include the shift operator. We further discuss the unitarity and stability of constructed non-supersymmetric string vacua, with emphasizing the common features of them.

  20. Non-existence of dynamical perturbations of Schwarzschild with vanishing self-dual part

    Science.gov (United States)

    Wald, R. M.

    1986-01-01

    A recent proposal of Ashtekar (1985) for the canonical quantisation of gravity involves a new choice of a (complex) polarisation on the (real) phase space of general relativity. In order for the 'four dimensional' version of Ashtekar's proposal to be viable, it is necessary that for an arbitrary (real) background solution there exist a sufficient number of (complex) solutions of the linearised Einstein equation with perturbed Weyl spinor having vanishing self-dual part. It is shown that this is not the case by explicitly demonstrating that for the Schwarzschild spacetime, aside from stationary perturbations, there are no such linearised solutions which can be expressed as superpositions of modes of real frequencies. The viability of the '3+1 version' of Ashtekar's proposal is not affected by these considerations.

  1. Achieving a vanishing SNR-gap to exact lattice decoding at a subexponential complexity

    CERN Document Server

    Singh, Arun; Jalden, Joakim

    2011-01-01

    The work identifies the first lattice decoding solution that achieves, in the general outage-limited MIMO setting and in the high-rate and high-SNR limit, both a vanishing gap to the error-performance of the (DMT optimal) exact solution of preprocessed lattice decoding, as well as a computational complexity that is subexponential in the number of codeword bits. The proposed solution employs lattice reduction (LR)-aided regularized (lattice) sphere decoding and proper timeout policies. These performance and complexity guarantees hold for most MIMO scenarios, all reasonable fading statistics, all channel dimensions and all full-rate lattice codes. In sharp contrast to the above manageable complexity, the complexity of other standard preprocessed lattice decoding solutions is shown here to be extremely high. Specifically the work is first to quantify the complexity of these lattice (sphere) decoding solutions and to prove the surprising result that the complexity required to achieve a certain rate-reliability pe...

  2. Tachyon cosmology with non-vanishing minimum potential: a unified model

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huiquan, E-mail: hqli@ustc.edu.cn [Interdisciplinary Center for Theoretical Study, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2012-07-01

    We investigate the tachyon condensation process in the effective theory with non-vanishing minimum potential and its implications to cosmology. It is shown that the tachyon condensation on an unstable three-brane described by this modified tachyon field theory leads to lower-dimensional branes (defects) forming within a stable three-brane. Thus, in the cosmological background, we can get well-behaved tachyon matter after tachyon inflation, (partially) avoiding difficulties encountered in the original tachyon cosmological models. This feature also implies that the tachyon inflated and reheated universe is followed by a Chaplygin gas dark matter and dark energy universe. Hence, such an unstable three-brane behaves quite like our universe, reproducing the key features of the whole evolutionary history of the universe and providing a unified description of inflaton, dark matter and dark energy in a very simple single-scalar field model.

  3. Brane solutions sourced by a scalar with vanishing potential and classification of scalar branes

    Energy Technology Data Exchange (ETDEWEB)

    Cadoni, Mariano [Dipartimento di Fisica, Università di Cagliari,Cittadella Universitaria, 09042 Monserrato (Italy); INFN, Sezione di Cagliari,Cagliari (Italy); Franzin, Edgardo [Dipartimento di Fisica, Università di Cagliari,Cittadella Universitaria, 09042 Monserrato (Italy); INFN, Sezione di Cagliari,Cagliari (Italy); CENTRA, Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa,Avenida Rovisco Pais 1, 1049 Lisboa (Portugal); Serra, Matteo [Dipartimento di Matematica, Sapienza Università di Roma,Piazzale Aldo Moro 2, 00185 Roma (Italy)

    2016-01-20

    We derive exact brane solutions of minimally coupled Einstein-Maxwell-scalar gravity in d+2 dimensions with a vanishing scalar potential and we show that these solutions are conformal to the Lifshitz spacetime whose dual QFT is characterized by hyperscaling violation. These solutions, together with the AdS brane and the domain wall sourced by an exponential potential, give the complete list of scalar branes sourced by a generic potential having simple (scale-covariant) scaling symmetries not involving Galilean boosts. This allows us to give a classification of both simple and interpolating brane solution of minimally coupled Einstein-Maxwell-scalar gravity having no Schrödinger isometries, which may be very useful for holographic applications.

  4. Four-loop QCD propagators and vertices with one vanishing external momentum

    Science.gov (United States)

    Ruijl, B.; Ueda, T.; Vermaseren, J. A. M.; Vogt, A.

    2017-06-01

    We have computed the self-energies and a set of three-particle vertex functions for massless QCD at the four-loop level in the \\overline{MS} renormalization scheme. The vertex functions are evaluated at points where one of the momenta vanishes. Analytical results are obtained for a generic gauge group and with the full gauge dependence, which was made possible by extensive use of the Forcer program for massless four-loop propagator integrals. The bare results in dimensional regularization are provided in terms of master integrals and rational coefficients; the latter are exact in any space-time dimension. Our results can be used for further precision investigations of the perturbative behaviour of the theory in schemes other than \\overline{MS} . As an example, we derive the five-loop beta function in a relatively common alternative, the minimal momentum subtraction (MiniMOM) scheme.

  5. Vanishing Higgs potential at the Planck scale in singlets extension of the standard model

    CERN Document Server

    Haba, Naoyuki; Kaneta, Kunio; Takahashi, Ryo

    2014-01-01

    We discuss the realization of a vanishing Higgs potential at the Planck scale, which is required by the multiple point criticality principle, in the standard model with singlet scalar dark matter and a right-handed neutrino. We find the scalar dark matter and the right-handed neutrino play crucial roles, and their masses, $m_S$ and $M_R$, must be $8.0\\times10^2~{\\rm GeV}\\leq m_S\\leq1.2\\times10^3~{\\rm GeV}$ and $6.3\\times10^{13}~{\\rm GeV}\\leq M_R\\leq1.6\\times10^{14}~{\\rm GeV}$ within current experimental values of the Higgs and top masses. This scenario is consistent with current dark matter direct search experiments, and will be confirmed by future experiments such as LUX with further exposure and/or XENON1T.

  6. Pinch-off of axisymmetric vortex pairs in the limit of vanishing vortex line curvature

    Science.gov (United States)

    Sadri, V.; Krueger, P. S.

    2016-07-01

    Pinch-off of axisymmetric vortex pairs generated by flow between concentric cylinders with radial separation ΔR was studied numerically and compared with planar vortex dipole behavior. The axisymmetric case approaches planar vortex dipole behavior in the limit of vanishing ΔR. The flow was simulated at a jet Reynolds number of 1000 (based on ΔR and the jet velocity), jet pulse length-to-gap ratio ( /L Δ R ) in the range 10-20, and gap-to-outer radius ratio ( /Δ R R o ) in the range 0.01-0.1. Contrary to investigations of strictly planar flows, vortex pinch-off was observed for all gap sizes investigated. This difference was attributed to the less constrained geometry considered, suggesting that even very small amounts of vortex line curvature and/or vortex stretching may disrupt the absence of pinch-off observed in strictly planar vortex dipoles.

  7. The Design of the Valsartan for Attenuating Disease Evolution in Early Sarcomeric Hypertrophic Cardiomyopathy (VANISH) Trial.

    Science.gov (United States)

    Ho, Carolyn Y; McMurray, John J V; Cirino, Allison L; Colan, Steven D; Day, Sharlene M; Desai, Akshay S; Lipshultz, Steven E; MacRae, Calum A; Shi, Ling; Solomon, Scott D; Orav, E John; Braunwald, Eugene

    2017-05-01

    Hypertrophic cardiomyopathy (HCM) is often caused by sarcomere gene mutations, resulting in left ventricular hypertrophy (LVH), myocardial fibrosis, and increased risk of sudden cardiac death and heart failure. Studies in mouse models of sarcomeric HCM demonstrated that early treatment with an angiotensin receptor blocker (ARB) reduced development of LVH and fibrosis. In contrast, prior human studies using ARBs for HCM have targeted heterogeneous adult cohorts with well-established disease. The VANISH trial is testing the safety and feasibility of disease-modifying therapy with an ARB in genotyped HCM patients with early disease. A randomized, placebo-controlled, double-blind clinical trial is being conducted in sarcomere mutation carriers, 8 to 45 years old, with HCM and no/minimal symptoms, or those with early phenotypic manifestations but no LVH. Participants are randomly assigned to receive valsartan 80 to 320 mg daily (depending on age and weight) or placebo. The primary endpoint is a composite of 9 z-scores in domains representing myocardial injury/hemodynamic stress, cardiac morphology, and function. Total z-scores reflecting change from baseline to final visits will be compared between treatment groups. Secondary endpoints will assess the impact of treatment on mutation carriers without LVH, and analyze the influence of age, sex, and genotype. The VANISH trial is testing a new strategy of disease modification for treating sarcomere mutation carriers with early HCM, and those at risk for its development. In addition, further insight into disease mechanisms, response to therapy, and phenotypic evolution will be gained. Copyright © 2017. Published by Elsevier Inc.

  8. Closed gastroschisis, vanishing midgut and extreme short bowel syndrome: Case report and review of the literature.

    Science.gov (United States)

    Dennison, F A

    2016-08-01

    Gastroschisis alone has excellent survival rates. Occasionally reported is closed gastroschisis, leading to vanishing small bowel and extreme short bowel syndrome. It is believed that the abdominal wall defect can contract or close in utero, which leads to strangulation of the eviscerated bowel and the rare "vanishing gut syndrome." This has a very poor prognosis with mortality as high as 70%. An 18-year-old primigravid patient's 13 week scan diagnosed a large gastroschisis affecting the fetus. After counselling, she decided to continue with the pregnancy. Between 20 and 22 weeks, the gastroschisis disappeared, and the bowel within the abdomen became markedly dilated. Spontaneous labour occurred at 33 + 3 weeks gestation. There was no abdominal wall defect seen at delivery. Imaging and an exploratory laparotomy demonstrated absence of most of the midgut. Because available options for treatment would be very aggressive and risky, palliative care was thought to be the most feasible and practical option. He died at home on day 29 after birth. Extreme short gut syndrome (less than 25 cm of remaining small bowel) is rare. There are 13 reported cases in the literature from year 2000 to 2013. Treatment is aggressive and involves a bowel lengthening procedure or small bowel transplant. All require total parenteral nutrition and liver failure, and liver transplant is a common complication. Of these cases, 12 were born alive and 7 had aggressive treatment. Only two cases were confirmed to still be alive in infancy. If gastroschisis is seen to be reducing and "disappearing" antenatally, parents should be made aware of this rare complication so that they might be prepared if a poor outcome is anticipated.

  9. Vanishing point attracts gaze in free-viewing and visual search tasks.

    Science.gov (United States)

    Borji, Ali; Feng, Mengyang; Lu, Huchuan

    2016-11-01

    Several structural scene cues such as gist, layout, horizontal line, openness, and depth have been shown to guide scene perception (e.g., Oliva & Torralba, 2001); Ross & Oliva, 2009). Here, to investigate whether vanishing point (VP) plays a significant role in gaze guidance, we ran two experiments. In the first one, we recorded fixations of 10 observers (six male, four female; mean age 22; SD = 0.84) freely viewing 532 images, out of which 319 had a VP (shuffled presentation; each image for 4 s). We found that the average number of fixations at a local region (80 × 80 pixels) centered at the VP is significantly higher than the average fixations at random locations (t test; n = 319; p search for a target character (T or L) placed randomly on a 3 × 3 imaginary grid overlaid on top of an image. Subjects reported their answers by pressing one of the two keys. Stimuli consisted of 270 color images (180 with a single VP, 90 without). The target happened with equal probability inside each cell (15 times L, 15 times T). We found that subjects were significantly faster (and more accurate) when the target appeared inside the cell containing the VP compared to cells without the VP (median across 14 subjects 1.34 s vs. 1.96 s; Wilcoxon rank-sum test; p = 0.0014). These findings support the hypothesis that vanishing point, similar to face, text (Cerf, Frady, & Koch, 2009), and gaze direction Borji, Parks, & Itti, 2014) guides attention in free-viewing and visual search tasks.

  10. Psychological vulnerability of singleton children after the 'vanishing' of a co-twin following assisted reproduction.

    Science.gov (United States)

    De Pascalis, Leonardo; Monti, Fiorella; Agostini, Francesca; Fagandini, Piergiuseppina; La Sala, Giovanni B; Blickstein, Isaac

    2008-02-01

    We test the hypothesis that parents who conceived twins by assisted reproduction technology (ART), but experienced loss of one twin, have a different parental-child relationship compared with ART parents following a singleton pregnancy. We used the 1994-2005 ART database of the Centre for Infertility of the Arcispedale Santa Maria Nuova in Reggio Emilia, Italy to identify families of 53 singleton births after the 'vanishing' twin syndrome. The controls comprised 106 families who conceived and delivered singletons, matched for gestational age (>or= 28 or= 32 or= 37 weeks), maternal age (or= 35 40 years), child's age (1-3, 4-6, and 7-11 years) and child's gender. We completed 3 tests: a sociodemographic questionnaire, the QUIT - Italian Questionnaires of Temperament - motor scale, and the Child Vulnerability Scale. We found that children in the study had significantly more difficulties at the beginning of nursery school (p = .002) and kindergarten (p = .0005), with more frequent anxiety of separation from the parents (nursery school, p = .009; kindergarten, p = .001). We found a lower mean QUIT motor score for the 7- to 11-year-old children when compared to the general Italian normative values, suggesting that parents perceived their children as having more motor difficulties. In contrast, analysis of the Child Vulnerability Scale showed that significantly more parents (15.1%) from the controls perceived their child as vulnerable compared to those from the study group (3.8%), p = .034. We conclude that despite the perceived motor difficulties and the difficulties in the process of individuation-separation that appear at the beginning of the different educational circumstances, parents of singletons following the 'vanishing' twin syndrome perceive their children as 'invincible', and thus less vulnerable compared to controls.

  11. Microscopic phase-field simulation for coarsening behavior of L12 and DO22 phases of Ni75CrxAl25-x alloy

    Institute of Scientific and Technical Information of China (English)

    LU Yan-li; CHEN Zheng; ZHANG Jing

    2008-01-01

    Based on the microscopic phase-field dynamic model and the microetasticity theory, the coarsening behavior of L12 and DO22 phases in Ni75CrxAl25-x alloy was simulated. The results show that the initial irregular shaped, randomly distributed L12 and DO22 phases are gradually transformed into cuboidal shape with round comer, regularly aligned along directions [100] and [001], and highly preferential selected microstructure is formed during the later stage of precipitation. The elastic field produced by the lattice mismatch between the coherent precipitates and the matrix has a strong influence on the coarsening kinetics, and there is no linear relationship between the cube of the average size of precipitates and the aging time, which does not agree with the results predicted by the classical Lifshitz-Slyozov-Wagner. The coarsening processes of L12 and DO22 phases are retarded in elastically constrained system. In the concurrent system of L12 and DO22 phases, there are two types of coarsening modes: the migration of antiphase domain boundaries and the interphase Ostwald ripening.

  12. Precipitates and Particles Coarsening of 9Cr-1.7W-0.4Mo-Co Ferritic Heat-Resistant Steel after Isothermal Aging.

    Science.gov (United States)

    Gao, Qiuzhi; Zhang, Yanan; Zhang, Hailian; Li, Huijun; Qu, Fu; Han, Jian; Lu, Cheng; Wu, Bintao; Lu, Yao; Ma, Yan

    2017-07-19

    The precipitates obtained by EPE technology from the 9Cr-1.7W-0.4Mo-Co ferritic heat-resistant steel subject to isothermal aging were investigated using SEM, TEM and XRD. The particle size distribution and the coarsening kinetics of M23C6 with duration of isothermal aging were also analyzed with or without consideration of Laves phase. The results show that the isolated dislocations were detected in delta ferrite interior, and the precipitates on delta ferrite and martensite boundaries are obviously larger than other locations. Fe2W-Laves phase can only be found as duration of aging time to 2000 h, and is preferential to form adjacent to M23C6 particles. The small M23C6 particles firstly coarsen, but the large M23C6 are relatively stable during short aging. The total coarsening rate of M23C6 precipitates is 9.75 × 10(-28)m(3)s(-1), and the coarsening of M23C6 depends on the formation of Laves phase.

  13. Thermal conductivity of nonlinear waves in disordered chains

    Indian Academy of Sciences (India)

    Sergej Flach; Mikhail Ivanchenko; Nianbei Li

    2011-11-01

    We present computational data on the thermal conductivity of nonlinear waves in disordered chains. Disorder induces Anderson localization for linear waves and results in a vanishing conductivity. Cubic nonlinearity restores normal conductivity, but with a strongly temperature-dependent conductivity (). We find indications for an asymptotic low-temperature ∼ 4 and intermediate temperature ∼ 2 laws. These findings are in accord with theoretical studies of wave packet spreading, where a regime of strong chaos is found to be intermediate, followed by an asymptotic regime of weak chaos (Laptyeva et al, Europhys. Lett. 91, 30001 (2010)).

  14. Properties of some nonlinear Schroedinger equations motivated through information theory

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Liew Ding; Parwani, Rajesh R, E-mail: parwani@nus.edu.s [Department of Physics, National University of Singapore, Kent Ridge (Singapore)

    2009-06-01

    We update our understanding of nonlinear Schroedinger equations motivated through information theory. In particular we show that a q-deformation of the basic nonlinear equation leads to a perturbative increase in the energy of a system, thus favouring the simplest q = 1 case. Furthermore the energy minimisation criterion is shown to be equivalent, at leading order, to an uncertainty maximisation argument. The special value eta = 1/4 for the interpolation parameter, where leading order energy shifts vanish, implies the preservation of existing supersymmetry in nonlinearised supersymmetric quantum mechanics. Physically, eta might be encoding relativistic effects.

  15. Massive gravity: nonlinear instability of the homogeneous and isotropic universe

    CERN Document Server

    De Felice, Antonio; Mukohyama, Shinji

    2012-01-01

    We study the propagating modes for nonlinear massive gravity on a Bianchi type--I manifold. We analyze their kinetic terms and dispersion relations as the background manifold approaches the homogeneous and isotropic limit. We show that in this limit, at least one ghost always exists and that its frequency tends to vanish for large scales, meaning that it cannot be integrated out from the low energy effective theory. Since this ghost mode can be considered as a leading nonlinear perturbation around a homogeneous and isotropic background, we conclude that the universe in this theory must be either inhomogeneous or anisotropic.

  16. Nonlinear optimization

    CERN Document Server

    Ruszczynski, Andrzej

    2011-01-01

    Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates t

  17. Simplified Model of Nonlinear Landau Damping

    Energy Technology Data Exchange (ETDEWEB)

    N. A. Yampolsky and N. J. Fisch

    2009-07-16

    The nonlinear interaction of a plasma wave with resonant electrons results in a plateau in the electron distribution function close to the phase velocity of the plasma wave. As a result, Landau damping of the plasma wave vanishes and the resonant frequency of the plasma wave downshifts. However, this simple picture is invalid when the external driving force changes the plasma wave fast enough so that the plateau cannot be fully developed. A new model to describe amplification of the plasma wave including the saturation of Landau damping and the nonlinear frequency shift is proposed. The proposed model takes into account the change of the plasma wave amplitude and describes saturation of the Landau damping rate in terms of a single fluid equation, which simplifies the description of the inherently kinetic nature of Landau damping. A proposed fluid model, incorporating these simplifications, is verified numerically using a kinetic Vlasov code.

  18. Riemann–Cartan Geometry of Nonlinear Dislocation Mechanics

    KAUST Repository

    Yavari, Arash

    2012-03-09

    We present a geometric theory of nonlinear solids with distributed dislocations. In this theory the material manifold-where the body is stress free-is a Weitzenböck manifold, that is, a manifold with a flat affine connection with torsion but vanishing non-metricity. Torsion of the material manifold is identified with the dislocation density tensor of nonlinear dislocation mechanics. Using Cartan\\'s moving frames we construct the material manifold for several examples of bodies with distributed dislocations. We also present non-trivial examples of zero-stress dislocation distributions. More importantly, in this geometric framework we are able to calculate the residual stress fields, assuming that the nonlinear elastic body is incompressible. We derive the governing equations of nonlinear dislocation mechanics covariantly using balance of energy and its covariance. © 2012 Springer-Verlag.

  19. Nonlinear channelizer

    Science.gov (United States)

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  20. The Vanished Child: An inquiry into figures and their modes of appearance

    Directory of Open Access Journals (Sweden)

    Bertrand Gervais

    2010-12-01

    Full Text Available Sophie Calle's texts are elaborate devices that facilitate the production of figures, of complex symbolic entities. In fact, her work enables us to better understand how figures emerge and unfold in the imaginary. Thus, we find in her Disparitions (Disappearances, a startling figure, which we can name the "Vanished Child". I will present this figure and explain how it stems from the description of a painting by Rembrandt, stolen at the Gardner Museum in Boston. I will start by identifying some of the essential processes implied in the identification of a figure, and, to do so, I will give two short examples, drawn from Witold Gombrowicz and Don DeLillo. Then, after having described in details the figure of the Vanished Child, I will argue, following the French art historian Georges Didi-Huberman in his reading of Walter Benjamin, that figures are auratic objects. Dans ses textes, Sophie Calle emploie des techniques détaillées qui facilitent la production de figures, d'entités symboliques complexes. Son œuvre nous permet effectivement de mieux comprendre comment les figures émergent et se déploient dans l'imaginaire. Ainsi, nous trouvons dans ses Disparitions (Disappearances une figure surprenante que nous pouvons désigner comme « l'enfant disparu ». Je présenterai cette figure en expliquant comment elle découle de la description d'un tableau de Rembrandt volé au musée Gardner à Boston. J'identifierai d'abord quelques-uns des procédés essentiels à l'identification d'une figure, et pour ce faire je donnerai deux exemples, tirés des œuvres de Witold Gombrowicz et Don DeLillo. Puis je décrirai de façon détaillée la figure de l'enfant disparu, avant de démontrer le caractère auratique des figures à partir de la lecture de Walter Benjamin qu'exécute l'historien de l'art français Georges Didi-Huberman.

  1. Nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Turchetti, G. (Bologna Univ. (Italy). Dipt. di Fisica)

    1989-01-01

    Research in nonlinear dynamics is rapidly expanding and its range of applications is extending beyond the traditional areas of science where it was first developed. Indeed while linear analysis and modelling, which has been very successful in mathematical physics and engineering, has become a mature science, many elementary phenomena of intrinsic nonlinear nature were recently experimentally detected and investigated, suggesting new theoretical work. Complex systems, as turbulent fluids, were known to be governed by intrinsically nonlinear laws since a long time ago, but received purely phenomenological descriptions. The pioneering works of Boltzmann and Poincare, probably because of their intrinsic difficulty, did not have a revolutionary impact at their time; it is only very recently that their message is reaching a significant number of mathematicians and physicists. Certainly the development of computers and computer graphics played an important role in developing geometric intuition of complex phenomena through simple numerical experiments, while a new mathematical framework to understand them was being developed.

  2. Vanishing tilt-to-length coupling for a singular case in two-beam laser interferometers with Gaussian beams

    CERN Document Server

    Schuster, Sönke; Tröbs, Michael; Heinzel, Gerhard

    2014-01-01

    The omnipresent tilt-to-length coupling in two-beam laser interferometers, frequently a nuisance in precision measurements, vanishes for the singular case of two beams with identical parameters and complete detection of both beams without clipping. This effect has been observed numerically and is explained in this paper by the cancellation of two very different effects of equal magnitude and opposite sign.

  3. Bore holes and the vanishing of guinea worm disease in Ghana's upper region.

    Science.gov (United States)

    Hunter, J M

    1997-07-01

    Ghana's Upper Region provides an excellent example of the beneficial effects of improved water security provided by hand-pump tube wells. Following a Ghana-Canada bilateral development project that installed some 2500 pumps, protection rates against guinea worm disease may be estimated as 88% in the west, and 96% in the east. Survey comparisons between ca 1960 and 1990 show that dracunculiasis declined in 32 of a total of 38 areas. The shadow of guinea worm has been lifted from the land and, in many areas, a true "vanishing" has occurred. The few areas of disease increase are characterized by the lowest population densities, pioneer settlement for cotton farming, and an absence of bore holes. Vagaries of development have inadvertently produced disease transformations or "metamorphoses" from dracunculiasis to elephantiasis (lymphatic filariasis) in one area, and to red water disease (schistosomiasis hematobium) in other areas. Correlative associations between pump densities and guinea worm disease are weakened by the large size of areas for which disease is reported in 1990. One preliminary finding is that geographical distance to the pump is a stronger influence than demographic pressure on pumps, regarding dracunculiasis. Diminishing returns on higher pump densities in many areas support the idea of making fuller, safer use of supplementary non-pump water. Despite crises of fee payment and pump maintenance, the rural bore hole project has struck a mortal blow against guinea worm, and permanently raised the quality of life in the Upper Region.

  4. String Theory in Polar Coordinates and the Vanishing of the One-Loop Rindler Entropy

    CERN Document Server

    Mertens, Thomas G; Zakharov, Valentin I

    2016-01-01

    We analyze the string spectrum of flat space in polar coordinates, following the small curvature limit of the $SL(2,\\mathbb{R})/U(1)$ cigar CFT. We first analyze the partition function of the cigar itself, making some clarifications of the structure of the spectrum that have escaped attention up to this point. The superstring spectrum (type 0 and type II) is shown to exhibit an involution symmetry, that survives the small curvature limit. We classify all marginal states in polar coordinates for type II superstrings, with emphasis on their links and their superconformal structure. This classification is confirmed by an explicit large $\\tau_2$ analysis of the partition function. Next we compare three approaches towards the type II genus one entropy in Rindler space: using a sum-over-fields strategy, using a Melvin model approach and finally using a saddle point method on the cigar partition function. In each case we highlight possible obstructions and motivate that the correct procedures yield a vanishing resul...

  5. Non-vanishing Superpotentials in Heterotic String Theory and Discrete Torsion

    CERN Document Server

    Buchbinder, Evgeny I

    2016-01-01

    We study the non-perturbative superpotential in E_8 x E_8 heterotic string theory on a non-simply connected Calabi-Yau manifold X, as well as on its simply connected covering space \\tilde{X}. The superpotential is induced by the string wrapping holomorphic, isolated, genus 0 curves. According to the residue theorem of Beasley and Witten, the non-perturbative superpotential must vanish in a large class of heterotic vacua because the contributions from curves in the same homology class cancel each other. We point out, however, that in certain cases the curves treated in the residue theorem as lying in the same homology class, can actually have different area with respect to the physical Kahler form and can be in different homology classes. In these cases, the residue theorem is not directly applicable and the structure of the superpotential is more subtle. We show, in a specific example, that the superpotential is non-zero both on \\tilde{X} and on X. On the non-simply connected manifold X, we explicitly compute...

  6. String theory in polar coordinates and the vanishing of the one-loop Rindler entropy

    Science.gov (United States)

    Mertens, Thomas G.; Verschelde, Henri; Zakharov, Valentin I.

    2016-08-01

    We analyze the string spectrum of flat space in polar coordinates, following the small curvature limit of the SL(2,{R})/U(1) cigar CFT. We first analyze the partition function of the cigar itself, making some clarifications of the structure of the spectrum that have escaped attention up to this point. The superstring spectrum (type 0 and type II) is shown to exhibit an involution symmetry, that survives the small curvature limit. We classify all marginal states in polar coordinates for type II superstrings, with emphasis on their links and their superconformal structure. This classification is confirmed by an explicit large τ 2 analysis of the partition function. Next we compare three approaches towards the type II genus one entropy in Rindler space: using a sum-over-fields strategy, using a Melvin model approach as in [1] and finally using a saddle point method on the cigar partition function. In each case we highlight possible obstructions and motivate that the correct procedures yield a vanishing result: S = 0. We finally discuss how the QFT UV divergences of the fields in the spectrum disappear when computing the free energy and entropy using Euclidean techniques.

  7. String theory in polar coordinates and the vanishing of the one-loop Rindler entropy

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, Thomas G. [Joseph Henry Laboratories, Princeton University,Princeton, NJ 08544 (United States); Verschelde, Henri [Ghent University, Department of Physics and Astronomy,Krijgslaan, 281-S9, 9000 Gent (Belgium); Zakharov, Valentin I. [ITEP, B. Cheremushkinskaya 25, Moscow, 117218 (Russian Federation); Moscow Inst Phys & Technol,Dolgoprudny, Moscow Region, 141700 (Russian Federation); School of Biomedicine, Far Eastern Federal University,Sukhanova str 8, Vladivostok 690950 (Russian Federation)

    2016-08-19

    We analyze the string spectrum of flat space in polar coordinates, following the small curvature limit of the SL(2,ℝ)/U(1) cigar CFT. We first analyze the partition function of the cigar itself, making some clarifications of the structure of the spectrum that have escaped attention up to this point. The superstring spectrum (type 0 and type II) is shown to exhibit an involution symmetry, that survives the small curvature limit. We classify all marginal states in polar coordinates for type II superstrings, with emphasis on their links and their superconformal structure. This classification is confirmed by an explicit large τ{sub 2} analysis of the partition function. Next we compare three approaches towards the type II genus one entropy in Rindler space: using a sum-over-fields strategy, using a Melvin model approach as in http://dx.doi.org/10.1007/JHEP05(2015)106 and finally using a saddle point method on the cigar partition function. In each case we highlight possible obstructions and motivate that the correct procedures yield a vanishing result: S=0. We finally discuss how the QFT UV divergences of the fields in the spectrum disappear when computing the free energy and entropy using Euclidean techniques.

  8. Nonlinear Systems.

    Science.gov (United States)

    Seider, Warren D.; Ungar, Lyle H.

    1987-01-01

    Describes a course in nonlinear mathematics courses offered at the University of Pennsylvania which provides an opportunity for students to examine the complex solution spaces that chemical engineers encounter. Topics include modeling many chemical processes, especially those involving reaction and diffusion, auto catalytic reactions, phase…

  9. Strain-induced γ{sup '}-coarsening during aging of Ni-based superalloys under uniaxial load. Modeling and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mushongera, Leslie T.

    2016-07-28

    Turbine blades which are used in the hot paths of aerospace or industrial gas turbines are usually manufactured as casted single crystalline parts. However, even though grain boundaries are excluded, the degradation behavior of respectively developed single crystal nickel-base superalloys, is still quite complex involving a number of very different microscopic effects. One of these is the diffusion-limited coarsening of the γ{sup '}-precipitates. Long-term aging or creep loading along the <100> crystallographic orientation results in the anisotropic coarsening of the γ{sup '}-precipitates. In the end, the microstructure contains quite large, irregularly shaped precipitates or plate-like precipitates aligned either parallel (P-type rafts) or perpendicular (N-type rafts) to the loading direction. This behavior is detrimental for the properties of these materials since their superior properties emanate from the size, morphology and distribution of the γ{sup '}-precipitates [R. Reed: Cambridge University Press, (2006)]. In order to efficiently design these materials, the phenomenon of coarsening should be known in detail to optimize the materials accurately. On this background, the general objective of this thesis is to develop an integrated computational approach for simulating morphological evolution in single crystal Ni-base superalloys. As a first step towards that aim, a multi-component phase field model coupled to inputs from CALPHAD-type and kinetic databases for the relevant driving forces was developed based on the grand-potential formalism similar to Plapp [Phys. Rev. E, 84: 031601 (2011)]. The thermodynamic formulation of the model was validated by comparisons to ThermoCalc equilibrium calculations and DICTRA sharp-interface simulations. Phase field approaches that allow for anisotropies of the interfacial energy sufficiently high so that the interface develops sharp corners due to missing crystallographic orientations were formulated. This

  10. Implications of a zero-nonlinearity wavelength in optical fibers doped with silver nanoparticles

    CERN Document Server

    Bose, S; Chattopadhyay, R; Bhadra, S K; Agrawal, G P

    2016-01-01

    Photonic crystal fibers doped with silver nanoparticles exhibit the Kerr nonlinearity that can be positive or negative depending on wavelength and vanishes at a specific wavelength. We study numerically how the simultaneous presence of a zero-nonlinearity wavelength (ZNW) and a zero-dispersion wavelength affects evolution of soliton and supercontinuum generation inside such fibers and find a number of unique features. The existence of negative nonlinearity allows soliton formation even in the normaldispersion region of the fiber, and the ZNW acts as a barrier for the Raman-induced red shift of solitons.

  11. Continuous dependence estimates for viscosity solutions of fully nonlinear degenerate elliptic equations

    Directory of Open Access Journals (Sweden)

    Espen R. Jakobsen

    2002-05-01

    Full Text Available Using the maximum principle for semicontinuous functions [3,4], we prove a general ``continuous dependence on the nonlinearities'' estimate for bounded Holder continuous viscosity solutions of fully nonlinear degenerate elliptic equations. Furthermore, we provide existence, uniqueness, and Holder continuity results for bounded viscosity solutions of such equations. Our results are general enough to encompass Hamilton-Jacobi-Bellman-Isaacs's equations of zero-sum, two-player stochastic differential games. An immediate consequence of the results obtained herein is a rate of convergence for the vanishing viscosity method for fully nonlinear degenerate elliptic equations.

  12. Factors which influence directional coarsening of Gamma prime during creep in nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1984-01-01

    Changes in the morphology of the gamma prime precipitate were examined as a function of time during creep at 982 C in 001 oriented single crystals of a Ni-Al-Mo-Ta superalloy. In this alloy, which has a large negative misfit of -0.80 pct., the gamma prime particles link together during creep to form platelets, or rafts, which are aligned with their broad faces perpendicular to the applied tensile axis. The effects of initial microstructure and alloy composition of raft development and creep properties were investigated. Directional coarsening of gamma prime begins during primary creep and continues well after the onset of second state creep. The thickness of the rafts remains constant up through the onset of tertiary creep a clear indication of the stability of the finely-spaced gamma/gamma prime lamellar structure. The thickness of the rafts which formed was equal to the initial gamma prime size which was present prior to testing. The single crystals with the finest gamma prime size exhibited the longest creep lives, because the resultant rafted structure had a larger number of gamma/gamma prime interfaces per unit volume of material. Reducing the Mo content by only 0.73 wt. pct. increased the creep life by a factor of three, because the precipitation of a third phase was eliminated.

  13. Factors which influence directional coarsening of gamma-prime during creep in nickel-base superalloy single crystals

    Science.gov (United States)

    Mackay, R. A.; Ebert, L. J.

    1984-01-01

    Changes in the morphology of the gamma prime precipitate were examined as a function of the time during creep at 982 C in 001 oriented single crystals of a Ni-Al-Mo-Ta superalloy. In this alloy, which has a large negative misfit of -0.80 pct., the gamma prime particles link together during creep to form platelets, or rafts, which are aligned with their broad faces perpendicular to the applied tensile axis. The effects of initial microstructure and alloy composition of raft development and creep properties were investigated. Directional coarsening of gamma prime begins during primary creep and continues well after the onset of second state creep. The thickness of the rafts remains constant up through the onset of tertiary creep, a clear indication of the stability of the finely-spaced gamma/gamma prime lamellar structure. The thickness of the rafts which formed was equal to the initial gamma prime size which was present prior to testing. The single crystals with the finest gamma prime size exhibited the longest creep lives, because the resultant rafted structure had a larger number of gamma/gamma prime interfaces per unit volume of material. Reducing the Mo content by only 0.73 wt. pct. increased the creep life by a factor of three, because the precipitation of a third phase was eliminated.

  14. An error-estimate-free and remapping-free variational mesh refinement and coarsening method for dissipative solids at finite strains

    OpenAIRE

    Mosler, J.; Ortiz, M.

    2009-01-01

    A variational h-adaptive finite element formulation is proposed. The distinguishing feature of this method is that mesh refinement and coarsening are governed by the same minimization principle characterizing the underlying physical problem. Hence, no error estimates are invoked at any stage of the adaption procedure. As a consequence, linearity of the problem and a corresponding Hilbert-space functional framework are not required and the proposed formulation can be applied to hig...

  15. A New Coarsening Operator for the Optimal Preconditioning of the Dual and Primal Domain Decomposition Methods: Application to Problems with Severe Coefficient Jumps

    Science.gov (United States)

    Farhat, Charbel; Rixen, Daniel

    1996-01-01

    We present an optimal preconditioning algorithm that is equally applicable to the dual (FETI) and primal (Balancing) Schur complement domain decomposition methods, and which successfully addresses the problems of subdomain heterogeneities including the effects of large jumps of coefficients. The proposed preconditioner is derived from energy principles and embeds a new coarsening operator that propagates the error globally and accelerates convergence. The resulting iterative solver is illustrated with the solution of highly heterogeneous elasticity problems.

  16. Turbulence closure: turbulence, waves and the wave-turbulence transition – Part 1: Vanishing mean shear

    Directory of Open Access Journals (Sweden)

    H. Z. Baumert

    2009-03-01

    Full Text Available This paper extends a turbulence closure-like model for stably stratified flows into a new dynamic domain in which turbulence is generated by internal gravity waves rather than mean shear. The model turbulent kinetic energy (TKE, K balance, its first equation, incorporates a term for the energy transfer from internal waves to turbulence. This energy source is in addition to the traditional shear production. The second variable of the new two-equation model is the turbulent enstrophy (Ω. Compared to the traditional shear-only case, the Ω-equation is modified to account for the effect of the waves on the turbulence time and space scales. This modification is based on the assumption of a non-zero constant flux Richardson number in the limit of vanishing mean shear when turbulence is produced exclusively by internal waves. This paper is part 1 of a continuing theoretical development. It accounts for mean shear- and internal wave-driven mixing only in the two limits of mean shear and no waves and waves but no mean shear, respectively.

    The new model reproduces the wave-turbulence transition analyzed by D'Asaro and Lien (2000b. At small energy density E of the internal wave field, the turbulent dissipation rate (ε scales like ε~E2. This is what is observed in the deep sea. With increasing E, after the wave-turbulence transition has been passed, the scaling changes to ε~E1. This is observed, for example, in the highly energetic tidal flow near a sill in Knight Inlet. The new model further exhibits a turbulent length scale proportional to the Ozmidov scale, as observed in the ocean, and predicts the ratio between the turbulent Thorpe and Ozmidov length scales well within the range observed in the ocean.

  17. The clinical and pathological analysis of 24 children with vanishing bile duct syndrome

    Directory of Open Access Journals (Sweden)

    Shu-hong LIU

    2011-01-01

    Full Text Available Objective To investigate the clinical and pathological characteristics of vanishing bile duct syndrome(VBDS,and provide references for clinical diagnosis.Methods Twenty four children with VBDS diagnosed by liver biopsy were collected in 302 Hospital of PLA from 2007 to 2009.Liver tissues were stained with haematoxylin eosin staining.The clinical and pathological characteristics were analyzed.Results The mean age of all patients(mean SD was 4.08±3.11 years and the sex ratio(male to female was 2.4:1.The most common symptoms were jaundice and pruritus in 24 children with VBDS.The mean levels of ALT,AST,ALP,GGT and TBil were 203.45 239.42U/L,238.54 224.11U/L,524.04 300.96U/L,242.17 220.86U/L and 242.17 220.86 μmol/L,respectively.Nineteen of 24 cases were positive for anti-CMV IgM,anti-CMV IgG or CMV PP65.Five cases were undergone the operation of biliary atresia.The main pathological characteristic of VBDS was atresia or disappearance of interlobular bile ducts to various degrees.Moreover,histological changes varied with respect to different causes.Obvious inflammatory infiltration in the portal tracts and hepatocytes damage were more common in VBDS caused by cytomegalovirus(CMV infection.Conclusions The incidence of VBDS is higher in boys than in girls.CMV infection plays an important role in the progress of VBDS.Different pathological characteristics may exist in VBDS caused by different etiological factors.

  18. Paradoxical Sensitivity to an Integrated Stress Response Blocking Mutation in Vanishing White Matter Cells.

    Science.gov (United States)

    Sekine, Yusuke; Zyryanova, Alisa; Crespillo-Casado, Ana; Amin-Wetzel, Niko; Harding, Heather P; Ron, David

    2016-01-01

    The eukaryotic translation initiation factor eIF2B promotes mRNA translation as a guanine nucleotide exchange factor (GEF) for translation initiation factor 2 (eIF2). Endoplasmic reticulum (ER) stress-mediated activation of the kinase PERK and the resultant phosphorylation of eIF2's alpha subunit (eIF2α) attenuates eIF2B GEF activity thereby inducing an integrated stress response (ISR) that defends against protein misfolding in the ER. Mutations in all five subunits of human eIF2B cause an inherited leukoencephalopathy with vanishing white matter (VWM), but the role of the ISR in its pathogenesis remains unclear. Using CRISPR-Cas9 genome editing we introduced the most severe known VWM mutation, EIF2B4A391D, into CHO cells. Compared to isogenic wildtype cells, GEF activity of cells with the VWM mutation was impaired and the mutant cells experienced modest enhancement of the ISR. However, despite their enhanced ISR, imposed by the intrinsic defect in eIF2B, disrupting the inhibitory effect of phosphorylated eIF2α on GEF by a contravening EIF2S1/eIF2αS51A mutation that functions upstream of eIF2B, selectively enfeebled both EIF2B4A391D and the related severe VWM EIF2B4R483W cells. The basis for paradoxical dependence of cells with the VWM mutations on an intact eIF2α genotype remains unclear, as both translation rates and survival from stressors that normally activate the ISR were not reproducibly affected by the VWM mutations. Nonetheless, our findings support an additional layer of complexity in the development of VWM, beyond a hyperactive ISR.

  19. Athermal nonlinear elastic constants of amorphous solids.

    Science.gov (United States)

    Karmakar, Smarajit; Lerner, Edan; Procaccia, Itamar

    2010-08-01

    We derive expressions for the lowest nonlinear elastic constants of amorphous solids in athermal conditions (up to third order), in terms of the interaction potential between the constituent particles. The effect of these constants cannot be disregarded when amorphous solids undergo instabilities such as plastic flow or fracture in the athermal limit; in such situations the elastic response increases enormously, bringing the system much beyond the linear regime. We demonstrate that the existing theory of thermal nonlinear elastic constants converges to our expressions in the limit of zero temperature. We motivate the calculation by discussing two examples in which these nonlinear elastic constants play a crucial role in the context of elastoplasticity of amorphous solids. The first example is the plasticity-induced memory that is typical to amorphous solids (giving rise to the Bauschinger effect). The second example is how to predict the next plastic event from knowledge of the nonlinear elastic constants. Using the results of our calculations we derive a simple differential equation for the lowest eigenvalue of the Hessian matrix in the external strain near mechanical instabilities; this equation predicts how the eigenvalue vanishes at the mechanical instability and the value of the strain where the mechanical instability takes place.

  20. Coarsening of one-step deposited organolead triiodide perovskite films via Ostwald ripening for high efficiency planar-heterojunction solar cells.

    Science.gov (United States)

    Zhu, Weidong; Bao, Chunxiong; Wang, Yangrunqian; Li, Faming; Zhou, Xiaoxin; Yang, Jie; Lv, Bihu; Wang, Xiaoyong; Yu, Tao; Zou, Zhigang

    2016-05-01

    Large organolead triiodide perovskite (OTP) grains with little intragranular defects are beneficial to minimize carrier recombination, hence boosting cell performance. However, OTP films deposited by the widely used one-step spin-coating route are usually composed of small grains, because the poor thermal stability of OTP inherently restricts the processing window (temperature, time) during the film preparation, thus limiting grain coarsening in the film. Herein, the remarkable grain coarsening via Ostwald ripening in one-step deposited OTP films has been successfully realized by a facile and effective post-synthesis high-temperature heating treatment assisted with spin-coated CH3NH3I. By systematically investigating the heating treatment parameters, a high-quality OTP film with an enlarged average grain size from ∼280 nm to 1.2 μm, greatly enhanced crystallinity, and excellent stoichiometry is achieved. Benefiting from such improved features, this modified film shows significantly reduced defect states corresponding to the decrease of recombination centers, as well as enhanced carrier transport and injection properties, which lead to the dramatically boosted efficiency from 14.54% to 16.88% for planar-heterojunction solar cells. More importantly, the improved OTP film quality provides the possibility of thickening the absorber layer of cells to realize more sufficient absorption without serious aggravation of charge recombination. By further optimizing the thickness of the coarsened OTP films, highly efficient cells with relatively excellent reproducibility and an optimal efficiency of 19.24% are achieved.

  1. Nonlinear PDEs

    OpenAIRE

    2015-01-01

    From the Back Cover: The emphasis throughout the present volume is on the practical application of theoretical mathematical models helping to unravel the underlying mechanisms involved in processes from mathematical physics and biosciences. It has been conceived as a unique collection of abstract methods dealing especially with nonlinear partial differential equations (either stationary or evolutionary) that are applied to understand concrete processes involving some important applications re...

  2. Distinguishable RGE Running Effects Between Dirac Neutrinos and Majorana Neutrinos with Vanishing Majorana CP-Violating Phases

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In a novel parametrization of neutrino mixing and in the approximation of т-lepton dominance, we show that the one-loop renormalization-group equations (RGEs) of Dirac neutrinos are different from those of Majorana neutrinos even if two Majorana CP-violating phases vanish. As the latter can keep vanishing from the electroweak scale to the typical seesaw scale, it makes sense to distinguish between the RGE running effects of neutrino mixing parameters in Dirac and Majorana cases. The differences are found to be quite large in the minimal supersymmetric standard model with sizable tanβ, provided the masses of three neutrinos are nearly degenerate or have an inverted hierarchy.

  3. Uniform Regularity and Vanishing Dissipation Limit for the Full Compressible Navier-Stokes System in Three Dimensional Bounded Domain

    Science.gov (United States)

    Wang, Yong

    2016-09-01

    In the present paper, we study the uniform regularity and vanishing dissipation limit for the full compressible Navier-Stokes system whose viscosity and heat conductivity are allowed to vanish at different orders. The problem is studied in a three dimensional bounded domain with Navier-slip type boundary conditions. It is shown that there exists a unique strong solution to the full compressible Navier-Stokes system with the boundary conditions in a finite time interval which is independent of the viscosity and heat conductivity. The solution is uniformly bounded in {W^{1,infty}} and is a conormal Sobolev space. Based on such uniform estimates, we prove the convergence of the solutions of the full compressible Navier-Stokes to the corresponding solutions of the full compressible Euler system in {L^infty(0,T; L^2)}, {L^infty(0,T; H1)} and {L^infty([0,T]×Ω)} with a rate of convergence.

  4. FORMULASI VANISHING CREAM MINYAK ATSIRI RIMPANG JAHE (Zingiber officinale Roxb) DAN UJI AKTIVITAS REPELAN TERHADAP NYAMUK Aedes aegypti BETINA

    OpenAIRE

    Azis Ikhsanudin

    2012-01-01

    The essential oil of Ginger rhizome is a natural subtance which has been proved to have a repellent effect to the mosquito. The aim of this study was to know the effect of this subtance/these substances in vanishing cream dosage forms as repellant to the female Aedes aegypti mosquito. The essential oil of Ginger rhizome was isolated with aqueous vapor destillation. Then the result was determined for its physical properties, these were: viscosity, adhesivity, spreadibility and i...

  5. Non-vanishing $U_{e3}$ and $\\cos{2 \\theta_{23}}$ from a broken $Z_2$ symmetry

    CERN Document Server

    Grimus, Walter; Kaneko, S; Lavoura, L; Sawanaka, H; Tanimoto, M; Grimus, Walter; Joshipura, Anjan S.; Kaneko, Satoru; Lavoura, Lu\\'{i}s; Sawanaka, Hideyuki; Tanimoto, Morimitsu

    2004-01-01

    It is shown that the neutrino mass matrices in the flavour basis yielding a vanishing $U_{e3}$ are characterized by invariance under a class of effective $Z_2$ symmetries. A specific $Z_2$ in this class also leads to a maximal atmospheric mixing angle $\\theta_{23}$. The breaking of that $Z_2$ can be parameterized by two dimensionless quantities, $\\e$ and $\\e'$; the effects of $\\e, \\e' \

  6. The Fall of the Vanishing Interim Regime Hypothesis: Towards a New Paradigm of the Choice of the Exchange Rate Regimes

    OpenAIRE

    Michal Jurek

    2010-01-01

    This paper verifies strong and weak versions of the vanishing interim regime hypothesis (so-called bipolar view). It is shown herein that the strong as well as weak version of this hypothesis can be discredited. Empirical observations support the bipolar view only for the advanced countries, but not for emerging and developing ones. On the contrary – the number of interim regimes, used by emerging and developing countries more than doubled in the 1999–2008 period. Results of the logistic regr...

  7. Vacuum stability in the $U(1)_\\chi$ extended model with vanishing scalar potential at the Planck scale

    CERN Document Server

    Haba, Naoyuki

    2015-01-01

    We investigate the vacuum stability in a scale invariant local $U(1)_\\chi$ model with vanishing scalar potential at the Planck scale. We find that it is impossible to realize the Higgs mass of 125\\,GeV while keeping the Higgs quartic coupling $\\lambda_H$ to be positive in all energy scale, that is the same as the standard model. Once one allows $\\lambda_H0$ gives the upper bound in $N_\

  8. Review of Obstetrics and Perinatal Outcome of Multiple Pregnancies with Vanishing and Selective Embryo Reduction in an Oocyte Donation Program

    Institute of Scientific and Technical Information of China (English)

    Rodríguez-Gonzàlez M; García-Velasco JA; Remohí J; Pellicer A; Serra V

    2005-01-01

    Objective To check previous findings of the most common complications among pregnancies with vanishing embryo(VE) in another actual study retropective and in group of patiens with selective embryo reduction (SER)Methods We defined vanishing phenomenon as the spontaneous loss of one or more embryos after visualizing heart activity at the first trimester of pregnancy. Selective embryo reduction was performed between 8th-12th pregnancy week, through vaginal punction and aspiration of embryonic mass.Results Vanishing embryo was observed in 86patients (18.0%). In 61 patients (70.9%) this phenomenom happened before 9th pregnancy week. The incidence of VE increased with higher number of gestational sacs initially visualized (P<0.03). First trimester bleeding was more common among pregnancies with VE than in the control (P<0.005). The incidence of pregnancy induced hypertension was lower in pregnancies with VE than in the controls (P<0.03). In contrast, preterm spontaneous rupture of membranes was higher, although without statistical significance. Gestational age at delivery, mode of delivery and birth weight was similar in the group of VE and the controls (P=NS).Conclusion All these informations may be useful in counselling patients on the prognosis and outcome of pregnancies achieved by oocyte donation.

  9. Nonlinear Spinor Fields in Bianchi type-V spacetime

    CERN Document Server

    Saha, Bijan

    2016-01-01

    A self-consistent system of nonlinear spinor and Bianchi type-V anisotropic gravitational fields are investigated. It is found that the presence of nontrivial non-diagonal components of the energy-momentum tensor of the spinor field imposes some severe restrictions to the system. As a result two different solutions are found. In one case the metric functions are similar to each other, i.e., $a_1 \\sim a_2 \\sim a_3$ and the spinor mass and spinor field nonlinearity do not disappear from the system. In this case the spacetime expands with acceleration in case of a positive self-coupling constant $\\lambda$. A negative $\\lambda$ gives rise to a cyclic or periodical mode of expansion. In the second case the spinor mass and the spinor field nonlinearity vanish and the Universe expands linearly with time.

  10. Testing and Inference in Nonlinear Cointegrating Vector Error Correction Models

    DEFF Research Database (Denmark)

    Kristensen, Dennis; Rahbek, Anders

    In this paper, we consider a general class of vector error correction models which allow for asymmetric and non-linear error correction. We provide asymptotic results for (quasi-)maximum likelihood (QML) based estimators and tests. General hypothesis testing is considered, where testing...... for linearity is of particular interest as parameters of non-linear components vanish under the null. To solve the latter type of testing, we use the so-called sup tests, which here requires development of new (uniform) weak convergence results. These results are potentially useful in general for analysis...... of non-stationary non-linear time series models. Thus the paper provides a full asymptotic theory for estimators as well as standard and non-standard test statistics. The derived asymptotic results prove to be new compared to results found elsewhere in the literature due to the impact of the estimated...

  11. Nonlinear Spinor Fields in Bianchi type-III spacetime

    CERN Document Server

    Saha, Bijan

    2016-01-01

    Within the scope of Bianchi type-III spacetime we study the role of spinor field on the evolution of the Universe as well as the influence of gravity on the spinor field. In doing so we have considered a polynomial type of nonlinearity. In this case the spacetime remains locally rotationally symmetric and anisotropic all the time. It is found that depending on the sign of nonlinearity the models allows both accelerated and oscillatory modes of expansion. The non-diagonal components of energy-momentum tensor though impose some restrictions on metric functions and components of spinor field, unlike Bianchi type I, V and $VI_0$ cases, they do not lead to vanishing mass and nonlinear terms of the spinor field.

  12. Causal Effect of Self-esteem on Cigarette Smoking Stages in Adolescents: Coarsened Exact Matching in a Longitudinal Study.

    Science.gov (United States)

    Khosravi, Ahmad; Mohammadpoorasl, Asghar; Holakouie-Naieni, Kourosh; Mahmoodi, Mahmood; Pouyan, Ali Akbar; Mansournia, Mohammad Ali

    2016-12-01

    Identification of the causal impact of self-esteem on smoking stages faces seemingly insurmountable problems in observational data, where self-esteem is not manipulable by the researcher and cannot be assigned randomly. The aim of this study was to find out if weaker self-esteem in adolescence is a risk factor of cigarette smoking in a longitudinal study in Iran. In this longitudinal study, 4,853 students (14-18 years) completed a self-administered multiple-choice anonym questionnaire. The students were evaluated twice, 12 months apart. Students were matched based on coarsened exact matching on pretreatment variables, including age, gender, smoking stages at the first wave of study, socioeconomic status, general risk-taking behavior, having a smoker in the family, having a smoker friend, attitude toward smoking, and self-injury, to ensure statistically equivalent comparison groups. Self-esteem was measured using the Rosenberg 10-item questionnaire and were classified using a latent class analysis. After matching, the effect of self-esteem was evaluated using a multinomial logistic model. In the causal fitted model, for adolescents with weaker self-esteem relative to those with stronger self-esteem, the relative risk for experimenters and regular smokers relative to nonsmokers would be expected to increase by a factor of 2.2 (1.9-2.6) and 2.0 (1.5-2.6), respectively. Using a causal approach, our study indicates that low self-esteem is consistently associated with progression in cigarette smoking stages.

  13. On the unboundedness of higher regularity Sobolev norms of solutions for the critical Schrödinger-Debye system with vanishing relaxation delay

    Science.gov (United States)

    Corcho, Adán J.; Drumond Silva, Jorge

    2017-01-01

    We consider the Schrödinger-Debye system in {{{R}}n} , for n  =  3,4. Developing on previously known local well-posedness results, we start by establishing global well-posedness in {{H}1}≤ft({{{R}}3}\\right)× {{L}2}≤ft({{{R}}3}\\right) for a broad class of initial data. We then concentrate on the initial value problem in n  =  4, which is the energy-critical dimension for the corresponding cubic nonlinear Schrödinger equation. We start by proving local well-posedness in {{H}1}≤ft({{{R}}4}\\right)× {{H}1}≤ft({{{R}}4}\\right) . Then, for the focusing case of the system, we derive a virial type identity and use it to prove that for radially symmetric smooth initial data with negative energy, there is a positive time T 0, depending only on the data, for which, either the {{H}1}≤ft({{{R}}4}\\right)× {{H}1}≤ft({{{R}}4}\\right) solutions blow-up in [0, T 0], or the higher regularity Sobolev norms are unbounded on the intervals [0, T ], for T  >  T 0, as the delay parameter vanishes. We finish by presenting a global well-posedness result for regular initial data which is small in the {{H}1}≤ft({{{R}}4}\\right)× {{H}1}≤ft({{{R}}4}\\right) norm.

  14. Multigrid Reduction in Time for Nonlinear Parabolic Problems

    Energy Technology Data Exchange (ETDEWEB)

    Falgout, R. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Manteuffel, T. A. [Univ. of Colorado, Boulder, CO (United States); O' Neill, B. [Univ. of Colorado, Boulder, CO (United States); Schroder, J. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-01-04

    The need for parallel-in-time is being driven by changes in computer architectures, where future speed-ups will be available through greater concurrency, but not faster clock speeds, which are stagnant.This leads to a bottleneck for sequential time marching schemes, because they lack parallelism in the time dimension. Multigrid Reduction in Time (MGRIT) is an iterative procedure that allows for temporal parallelism by utilizing multigrid reduction techniques and a multilevel hierarchy of coarse time grids. MGRIT has been shown to be effective for linear problems, with speedups of up to 50 times. The goal of this work is the efficient solution of nonlinear problems with MGRIT, where efficient is defined as achieving similar performance when compared to a corresponding linear problem. As our benchmark, we use the p-Laplacian, where p = 4 corresponds to a well-known nonlinear diffusion equation and p = 2 corresponds to our benchmark linear diffusion problem. When considering linear problems and implicit methods, the use of optimal spatial solvers such as spatial multigrid imply that the cost of one time step evaluation is fixed across temporal levels, which have a large variation in time step sizes. This is not the case for nonlinear problems, where the work required increases dramatically on coarser time grids, where relatively large time steps lead to worse conditioned nonlinear solves and increased nonlinear iteration counts per time step evaluation. This is the key difficulty explored by this paper. We show that by using a variety of strategies, most importantly, spatial coarsening and an alternate initial guess to the nonlinear time-step solver, we can reduce the work per time step evaluation over all temporal levels to a range similar with the corresponding linear problem. This allows for parallel scaling behavior comparable to the corresponding linear problem.

  15. Durability of treatment effect with polidocanol endovenous microfoam on varicose vein symptoms and appearance (VANISH-2).

    Science.gov (United States)

    Todd, Kenneth L; Wright, David I

    2015-07-01

    The objectives of this study were to assess the durability of response to treatment with polidocanol endovenous microfoam (Varithena; Provensis Ltd, a BTG International group company) and to assess the long-term safety of the study patients. This report presents efficacy and safety data from the day after visit 5/week 8 (the primary end point of the study) through the 1-year study visit. As the approved dose concentration is 1%, this analysis focuses on those patients who were randomized to polidocanol endovenous microfoam 1% at study visit 2. Because the objective of the 1-year analysis was to assess the durability of response to treatment with polidocanol endovenous microfoam 1%, the 1-year efficacy analyses based on the efficacy population included all patients who were randomized and received at least one treatment with polidocanol endovenous microfoam 1%. Efficacy end points in the Polidocanol Endovenous Microfoam Versus Vehicle for the Treatment of Saphenofemoral Junction Incompetence (VANISH-2) trial were evaluated at 1 year (n = 221; 96% of those completed the primary end-point measurement at week 8) and included the following: Varicose Vein Symptoms Questionnaire (VVSymQ, Provensis Ltd) score, an assessment of symptoms by patients using electronic daily diaries; Independent Photography Review: Visible Varicose Veins (IPR-V(3)) and Patient Self-assessment of Visible Varicose Veins (PA-V(3)) scores, the assessment of appearance by an Independent Physician Review panel and by patient self-assessment, respectively; duplex ultrasound response (physiologic response to treatment); Venous Clinical Severity Score (disease severity); and Venous Insufficiency Epidemiological and Economic Study on Quality of Life (VEINES-QOL) score (quality of life). Of the 230 patients who completed visit 5/week 8, 56 received polidocanol endovenous microfoam 1% at visit 2/week 0 and were subsequently assessed for efficacy at visit 5/week 8 and visit 10/1 year (one patient of the 57

  16. de Sitter limit of inflation and nonlinear perturbation theory

    CERN Document Server

    Jarnhus, Philip R

    2007-01-01

    We study the fourth order action of comoving curvature perturbations in an inflationary universe in order to understand more systematically the de Sitter limit in nonlinear cosmological perturbation theory. We derive the action of the curvature perturbations to fourth order in the comoving gauge, and show that it vanishes sufficiently fast in the de Sitter limit. By studying the de Sitter limit, we then extrapolate to the n'th order action of comoving curvature perturbations and discuss the slow-roll order of the n-point correlation function.

  17. Travelling and standing envelope solitons in discrete non-linear cyclic structures

    Science.gov (United States)

    Grolet, Aurelien; Hoffmann, Norbert; Thouverez, Fabrice; Schwingshackl, Christoph

    2016-12-01

    Envelope solitons are demonstrated to exist in non-linear discrete structures with cyclic symmetry. The analysis is based on the Non-Linear Schrodinger Equation for the weakly non-linear limit, and on numerical simulation of the fully non-linear equations for larger amplitudes. Envelope solitons exist for parameters in which the wave equation is focussing and they have the form of shape-conserving wave packages propagating roughly with group velocity. For the limit of maximum wave number, where the group velocity vanishes, standing wave packages result and can be linked via a bifurcation to the non-localised non-linear normal modes. Numerical applications are carried out on a simple discrete system with cyclic symmetry which can be seen as a reduced model of a bladed disk as found in turbo-machinery.

  18. Chaotic synchronization of two complex nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Gamal M. [Department of Mathematics, Faculty of Science, Assiut University, Assiut 71516 (Egypt)], E-mail: gmahmoud@aun.edu.eg; Mahmoud, Emad E. [Department of Mathematics, Faculty of Science, Sohag University (Egypt)], E-mail: emad_eluan@yahoo.com; Farghaly, Ahmed A. [Department of Mathematics, Faculty of Science, Assiut University, Assiut 71516 (Egypt)], E-mail: ahmed_1_66@yahoo.com; Aly, Shaban A. [Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut 71511 (Egypt)], E-mail: shhaly12@yahoo.com

    2009-12-15

    Synchronization is an important phenomenon commonly observed in nature. It is also often artificially induced because it is desirable for a variety of applications in physics, applied sciences and engineering. In a recent paper [Mahmoud GM, Mohamed AA, Aly SA. Strange attractors and chaos control in periodically forced complex Duffing's oscillators. Physica A 2001;292:193-206], a system of periodically forced complex Duffing's oscillators was introduced and shown to display chaotic behavior and possess strange attractors. Such complex oscillators appear in many problems of physics and engineering, as, for example, nonlinear optics, deep-water wave theory, plasma physics and bimolecular dynamics. Their connection to solutions of the nonlinear Schroedinger equation has also been pointed out. In this paper, we study the remarkable phenomenon of chaotic synchronization on these oscillator systems, using active control and global synchronization techniques. We derive analytical expressions for control functions and show that the dynamics of error evolution is globally stable, by constructing appropriate Lyapunov functions. This means that, for a relatively large set initial conditions, the differences between the drive and response systems vanish exponentially and synchronization is achieved. Numerical results are obtained to test the validity of the analytical expressions and illustrate the efficiency of these techniques for inducing chaos synchronization in our nonlinear oscillators.

  19. Vanishing Corrections for the Position in a Linear Model of FKPP Fronts

    Science.gov (United States)

    Berestycki, Julien; Brunet, Éric; Harris, Simon C.; Roberts, Matt

    2017-02-01

    Take the linearised FKPP equation {partialth = partial2xh + h} with boundary condition h( m( t), t) = 0. Depending on the behaviour of the initial condition h 0( x) = h( x, 0) we obtain the asymptotics—up to a o(1) term r( t)—of the absorbing boundary m( t) such that {ω(x) := lim_{tto∞} h(x + m(t) ,t)} exists and is non-trivial. In particular, as in Bramson's results for the non-linear FKPP equation, we recover the celebrated {-3/2 log t} correction for initial conditions decaying faster than {x^{ν}e^{-x}} for some {ν < -2}. Furthermore, when we are in this regime, the main result of the present work is the identification (to first order) of the r( t) term, which ensures the fastest convergence to {ω(x)}. When h 0( x) decays faster than {x^{ν}e^{-x}} for some {ν < -3}, we show that r( t) must be chosen to be {-3√{π/t}}, which is precisely the term predicted heuristically by Ebert-van Saarloos (Phys. D Nonlin. Phenom. 146(1): 1-99, 2000) in the non-linear case (see also Mueller and Munier Phys Rev E 90(4):042143, 2014, Henderson, Commun Math Sci 14(4):973-985, 2016, Brunet and Derrida Stat Phys 1-20, 2015). When the initial condition decays as {x^{ν}e^{-x}} for some {ν in [-3, -2)}, we show that even though we are still in the regime where Bramson's correction is {-3/2 log t}, the Ebert-van Saarloos correction has to be modified. Similar results were recently obtained by Henderson CommunMath Sci 14(4):973-985, 2016 using an analytical approach and only for compactly supported initial conditions.

  20. Nonlinear resonances

    CERN Document Server

    Rajasekar, Shanmuganathan

    2016-01-01

    This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...

  1. Nonlinear Dynamics

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    3.1 A Unified Nonlinear Feedback Functional Method for Study Both Control and Synchronization of Spatiotemporal Chaos Fang Jinqing Ali M. K. (Department of Physics, The University of Lethbridge,Lethbridge, Alberta T1K 3M4,Canada) Two fundamental questions dominate future chaos control theories.The first is the problem of controlling hyperchaos in higher dimensional systems.The second question has yet to be addressed:the problem of controlling spatiotemporal chaos in a spatiotemporal system.In recent years, control and synchronization of spatiotemporal chaos and hyperchaos have became a much more important and challenging subject. The reason for this is the control and synchronism of such behaviours have extensive and great potential of interdisciplinary applications, such as security communication, information processing, medicine and so on. However, this subject is not much known and remains an outstanding open.

  2. Maximal Saddle Solution of a Nonlinear Elliptic Equation Involving the -Laplacian

    Indian Academy of Sciences (India)

    Huahui Yan; Zhuoran Du

    2014-02-01

    A saddle solution is called maximal saddle solution if its absolute value is not smaller than those absolute values of any solutions that vanish on the Simons cone $\\mathcal{C} = \\{s = t\\}$ and have the same sign as - . We prove the existence of a maximal saddle solution of the nonlinear elliptic equation involving the -Laplacian, by using the method of monotone iteration, $$-_{p^u}=f(u) \\quad \\text{in} \\quad R^{2m},$$ where $2m≥ p > 2$.

  3. Boundary layers for self-similar viscous approximations of nonlinear hyperbolic systems

    CERN Document Server

    Christoforou, Cleopatra

    2011-01-01

    We provide a precise description of the set of residual boundary conditions generated by the self-similar viscous approximation introduced by Dafermos et al. We then apply our results, valid for both conservative and non conservative systems, to the analysis of the boundary Riemann problem and we show that, under appropriate assumptions, the limits of the self-similar and the classical vanishing viscosity approximation coincide. We require neither genuinely nonlinearity nor linear degeneracy of the characteristic fields.

  4. Three Gorges Dam controls sediment coarsening of the mud patch on the inner East China Sea shelf

    Science.gov (United States)

    Miao, Anyang; Chu, Zhongxin; Li, Yingkun

    2016-06-01

    The well-known Three Gorges Dam (TGD) within the Yangtze catchment launched its operation in 2003. The effect of the TGD operation on the sediment size on the East China Sea shelf is rarely known. High resolution (0.5 cm sampling) grain size analysis and 137Cs and 210Pb dating of the DH8-1 core were conducted with core collected from the distal part of a main sink for the modern Yangtze sediment entering the sea, the Min-Zhe Coastal Mud Deposits (MZCMD) on the inner East China Sea shelf. The 137Cs dating results show that the core DH8-1 formed during 1946-2012 with a mean deposition rate of 0.65 cm yr-1, indicating that the 0.5 cm sampling for grain size analysis in this local area could reflect environmental changes generally on a one-year time scale. The mean grain size of DH8-1 core sediment that deposited after 2003 is significantly larger than that deposited during 1988-2002. After ruling out other possible factors, we infer that the sediment coarsening of DH8-1 core after 2003 is attributed to the TGD operation which causes the erosion of the Yangtze subaqueous delta. Specifically, the TGD operation significantly intensifies the declining trend of the Yangtze sediment loads to the sea despite no decreased water discharge, which results in extensive erosion of the Yangtze subaqueous delta. The relatively coarse sediment of the subaqueous delta is eroded and resuspended by ocean dynamics and then transported by coastal current, finally depositing on the MZCMD area. In addition, the general sediment fining of core DH8-1 that deposited during 1988-2002, comparing with 1946-1987, is mainly caused by dam construction and soil and water conservation within the Yangtze catchment. Our findings are helpful for better understanding the effects of such a huge dam as the TGD on a sediment sink like the MZCMD of such a large river as the Yangtze River.

  5. Is There a Role for Oral Antibiotic Preparation Alone Before Colorectal Surgery? ACS-NSQIP Analysis by Coarsened Exact Matching.

    Science.gov (United States)

    Garfinkle, Richard; Abou-Khalil, Jad; Morin, Nancy; Ghitulescu, Gabriela; Vasilevsky, Carol-Ann; Gordon, Philip; Demian, Marie; Boutros, Marylise

    2017-07-01

    Recent studies demonstrated reduced postoperative complications using combined mechanical bowel and oral antibiotic preparation before elective colorectal surgery. The aim of this study was to assess the impact of these 2 interventions on surgical site infections, anastomotic leak, ileus, major morbidity, and 30-day mortality in a large cohort of elective colectomies. This is a retrospective comparison of 30-day outcomes using the American College of Surgeons National Surgical Quality Improvement Program colectomy-targeted database with coarsened exact matching. Interventions were performed in hospitals participating in the national surgical database. Adult patients who underwent elective colectomy from 2012 to 2014 were included. Preoperative bowel preparations were evaluated. The primary outcomes measured were surgical site infections, anastomotic leak, postoperative ileus, major morbidity, and 30-day mortality. A total of 40,446 patients were analyzed: 13,219 (32.7%), 13,935 (34.5%), and 1572 (3.9%) in the no-preparation, mechanical bowel preparation alone, and oral antibiotic preparation alone groups, and 11,720 (29.0%) in the combined preparation group. After matching, 9800, 1461, and 8819 patients remained in the mechanical preparation, oral antibiotic preparation, and combined preparation groups for comparison with patients without preparation. On conditional logistic regression of matched patients, oral antibiotic preparation alone was protective of surgical site infection (OR, 0.63; 95% CI, 0.45-0.87), anastomotic leak (OR, 0.60; 95% CI, 0.34-0.97), ileus (OR, 0.79; 95% CI, 0.59-0.98), and major morbidity (OR, 0.73; 95% CI, 0.55-0.96), but not mortality (OR, 0.32; 95% CI, 0.08-1.18), whereas a regimen of combined oral antibiotics and mechanical bowel preparation was protective for all 5 major outcomes. When directly compared with oral antibiotic preparation alone, the combined regimen was not associated with any difference in any of the 5 postoperative

  6. Short Communication on "Coarsening of Y-rich oxide particles in 9%Cr-ODS Eurofer steel annealed at 1350 °C"

    Science.gov (United States)

    Sandim, M. J. R.; Souza Filho, I. R.; Bredda, E. H.; Kostka, A.; Raabe, D.; Sandim, H. R. Z.

    2017-02-01

    Oxide-dispersion strengthened (ODS) Eurofer steel is targeted for structural applications in future fusion nuclear reactors. Samples were cold rolled down to 80% reduction in thickness and annealed at 1350 °C up to 8 h. The microstructural characterization was performed using Vickers microhardness testing, electron backscatter diffraction, scanning and scanning transmission electron microscopies. Experimental results provide evidence of coarsening of the Y-rich oxide particles in ODS-Eurofer steel annealed at 1350 °C within delta ferrite phase field.

  7. Precipitates and Particles Coarsening of 9Cr?1.7W?0.4Mo?Co Ferritic Heat-Resistant Steel after Isothermal Aging

    OpenAIRE

    Gao, Qiuzhi; Zhang, Yanan; Zhang, Hailian; Li, HuiJun; Qu, Fu; Han, Jian; Lu, Cheng; Wu, Bintao; Lu, Yao; Ma, Yan

    2017-01-01

    The precipitates obtained by EPE technology from the 9Cr-1.7W-0.4Mo-Co ferritic heat-resistant steel subject to isothermal aging were investigated using SEM, TEM and XRD. The particle size distribution and the coarsening kinetics of M23C6 with duration of isothermal aging were also analyzed with or without consideration of Laves phase. The results show that the isolated dislocations were detected in delta ferrite interior, and the precipitates on delta ferrite and martensite boundaries are ob...

  8. Influence of Grain Coarsening on the Creep Parameters During the Superplastic Deformation of a Severely Friction Stir Processed Al-Zn-Mg-Cu Alloy

    Science.gov (United States)

    Orozco-Caballero, Alberto; Ruano, Oscar A.; Carreño, Fernando

    2017-09-01

    During grain boundary sliding in ultrafine-grain materials at intermediate temperatures and high strain rates ( 10-2 s-1), apparent creep parameters usually deviate from the theoretical values, due to microstructural coarsening. An analysis has been carried out in a severely friction stir processed (FSP) 7075 alloy with three different ultra-fine grain sizes ( L), obtaining explicit grain size dependence of the creep parameters n ap = n ap( L) and Q ap = Q ap( L), confirming the validity of the theoretical values of these parameters in the constitutive equation.

  9. Vanishing viscosity as a selection principle for the Euler equations: The case of 3D shear flow

    CERN Document Server

    Bardos, Claude; Wiedemann, Emil

    2012-01-01

    We show that for a certain family of initial data, there exist non-unique weak solutions to the 3D incompressible Euler equations satisfying the weak energy inequality, whereas the weak limit of every sequence of Leray-Hopf weak solutions for the Navier-Stokes equations, with the same initial data, and as the viscosity tends to zero, is uniquely determined and equals the shear flow solution of the Euler equations. This simple example suggests that, also in more general situations, the vanishing viscosity limit of the Navier-Stokes equations could serve as a uniqueness criterion for weak solutions of the Euler equations.

  10. Vanishing current hysteresis under competing nuclear spin pumping processes in a quadruplet spin-blockaded double quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Amaha, S., E-mail: s-amaha@riken.jp [Quantum Spin Information Project, Japan Science and Technology Agency, ICORP, 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Quantum Functional System Research Group, RIKEN Center for Emergent Matter Science, RIKEN, 3-1 Wako-shi, Saitama 351-0198 (Japan); Hatano, T. [Quantum Spin Information Project, Japan Science and Technology Agency, ICORP, 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Department of Physics, Tohoku University, Sendai-shi, Miyagi 980-8578 (Japan); Tarucha, S. [Quantum Spin Information Project, Japan Science and Technology Agency, ICORP, 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198 (Japan); Quantum Functional System Research Group, RIKEN Center for Emergent Matter Science, RIKEN, 3-1 Wako-shi, Saitama 351-0198 (Japan); Department of Applied Physics, School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Gupta, J. A.; Austing, D. G. [National Research Council of Canada, M50, Montreal Road, Ottawa, Ontario K1A 0R6 (Canada)

    2015-04-27

    We investigate nuclear spin pumping with five-electron quadruplet spin states in a spin-blockaded weakly coupled vertical double quantum dot device. Two types of hysteretic steps in the leakage current are observed on sweeping the magnetic field and are associated with bidirectional polarization of nuclear spin. Properties of the steps are understood in terms of bias-voltage-dependent conditions for the mixing of quadruplet and doublet spin states by the hyperfine interaction. The hysteretic steps vanish when up- and down-nuclear spin pumping processes are in close competition.

  11. SYMMETRIC MODE INSTABILITY OF THE SLIPFLOW MODEL FOR FLOWS IN A MICROCHANNEL WITH A VANISHING REYNOLDS NUMBER

    Institute of Scientific and Technical Information of China (English)

    甘才俊; 吴子牛

    2003-01-01

    The slipflow model is usually used to study microflows when the Knudsen number lies between 0.01 and 0.1. The instability due to microscale effect seems to have never been studied before.In this paper we present preliminary results for the instability (not physical instability) of this model when applied to microchannel flow with a vanishing Reynolds number. The present paper is restricted to symmetrical mode. Both first-order and second-order slip boundary conditions will be considered.

  12. Fermionic dispersion relations at finite temperature and non-vanishing chemical potentials in the minimal standard model

    CERN Document Server

    Morales, J; Fonseca, F; Morales, John; Quimbay, Carlos; Fonseca, Frank

    1999-01-01

    We calculate the fermionic dispersion relations in the minimal standard model at finite temperature in presence of non-vanishing chemical potentials due to the CP-asymmetric fermionic background. The dispersion relations are calculated for a vacuum expectation value of the Higgs field equal to zero (unbroken electroweak symmetry). The calculation is performed in the real time formalism of the thermal field theory at one-loop order in a general $\\xi$ gauge. The fermionic self-energy is calculated at leading order in temperature and chemical potential and this fact permits us to obtain gauge invariant analytical expressions for the dispersion relations.

  13. Exponential vanishing of the ground-state gap of the quantum random energy model via adiabatic quantum computing

    Energy Technology Data Exchange (ETDEWEB)

    Adame, J.; Warzel, S., E-mail: warzel@ma.tum.de [Zentrum Mathematik, TU München, Boltzmannstr. 3, 85747 Garching (Germany)

    2015-11-15

    In this note, we use ideas of Farhi et al. [Int. J. Quantum. Inf. 6, 503 (2008) and Quantum Inf. Comput. 11, 840 (2011)] who link a lower bound on the run time of their quantum adiabatic search algorithm to an upper bound on the energy gap above the ground-state of the generators of this algorithm. We apply these ideas to the quantum random energy model (QREM). Our main result is a simple proof of the conjectured exponential vanishing of the energy gap of the QREM.

  14. Nonlinear Materials Characterization Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Nonlinear Materials Characterization Facility conducts photophysical research and development of nonlinear materials operating in the visible spectrum to protect...

  15. Nonlinear singular vectors and nonlinear singular values

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel concept of nonlinear singular vector and nonlinear singular value is introduced, which is a natural generalization of the classical linear singular vector and linear singular value to the nonlinear category. The optimization problem related to the determination of nonlinear singular vectors and singular values is formulated. The general idea of this approach is demonstrated by a simple two-dimensional quasigeostrophic model in the atmospheric and oceanic sciences. The advantage and its applications of the new method to the predictability, ensemble forecast and finite-time nonlinear instability are discussed. This paper makes a necessary preparation for further theoretical and numerical investigations.

  16. FORMULASI VANISHING CREAM MINYAK ATSIRI RIMPANG JAHE (Zingiber officinale Roxb DAN UJI AKTIVITAS REPELAN TERHADAP NYAMUK Aedes aegypti BETINA

    Directory of Open Access Journals (Sweden)

    Azis Ikhsanudin

    2012-11-01

    Full Text Available The essential oil of Ginger rhizome is a natural subtance which has been proved to have a repellent effect to the mosquito. The aim of this study was to know the effect of this subtance/these substances in vanishing cream dosage forms as repellant to the female Aedes aegypti mosquito. The essential oil of Ginger rhizome was isolated with aqueous vapor destillation. Then the result was determined for its physical properties, these were: viscosity, adhesivity, spreadibility and its repellant effect to mosquito as well. The vanishing cream formulation, containing variation of the essential oil concentration were prepared, these were: FI (formulation I, FII, FIII, FIV and FV, containing 6,25%, 12,5%, 15%, 20% and 25% of the essential oil respectivity. Each formulas were tested for their physical properties were viscosity, adhesivity, spreadibility and its repellant effect to mosquito as well. The datas were analyzed. Statistically using SPSS version 16 with Kolmogorov-Smirnov and continued with the t-test (Mann-Whitney (=0,05. The result showed that the duration of the adhesivity of FI was the longest than the others (1,37±0,15 minutes; the spreadibility of the FI was widest (71,69±1,76 mm2 , and the viscosity was the largert than others (27±0 cps. The repellant capasity of the FV was the longest than the others (47,3±1,80 minutes.

  17. Giant kerr nonlinearity, controlled entangled photons and polarization phase gates in coupled quantum-well structures.

    Science.gov (United States)

    Zhu, Chengjie; Huang, Guoxiang

    2011-11-07

    We study linear and nonlinear propagations of probe and signal pulses in a multiple quantum-well structure with a four-level, double Λ-type configuration. We show that slow, mutually matched group velocities and giant Kerr nonlinearity of the probe and the signal pulses may be achieved with nearly vanishing optical absorption. Based on these properties we demonstrate that two-qubit quantum polarization phase gates can be constructed and highly entangled photon pairs may be produced. In addition, we show that coupled slow-light soliton pairs with very low generation power can be realized in the system.

  18. Acceleration Control in Nonlinear Vibrating Systems based on Damped Least Squares

    CERN Document Server

    Pilipchuk, V N

    2011-01-01

    A discrete time control algorithm using the damped least squares is introduced for acceleration and energy exchange controls in nonlinear vibrating systems. It is shown that the damping constant of least squares and sampling time step of the controller must be inversely related to insure that vanishing the time step has little effect on the results. The algorithm is illustrated on two linearly coupled Duffing oscillators near the 1:1 internal resonance. In particular, it is shown that varying the dissipation ratio of one of the two oscillators can significantly suppress the nonlinear beat phenomenon.

  19. Coarsening and persistence in a one-dimensional system of orienting arrowheads: Domain-wall kinetics with A +B →0

    Science.gov (United States)

    Khandkar, Mahendra D.; Stinchcombe, Robin; Barma, Mustansir

    2017-01-01

    We demonstrate the large-scale effects of the interplay between shape and hard-core interactions in a system with left- and right-pointing arrowheads on a line, with reorientation dynamics. This interplay leads to the formation of two types of domain walls, > (B ). The correlation length in the equilibrium state diverges exponentially with increasing arrowhead density, with an ordered state of like orientations arising in the limit. In this high-density limit, the A domain walls diffuse, while the B walls are static. In time, the approach to the ordered state is described by a coarsening process governed by the kinetics of domain-wall annihilation A +B →0 , quite different from the A +A →0 kinetics pertinent to the Glauber-Ising model. The survival probability of a finite set of walls is shown to decay exponentially with time, in contrast to the power-law decay known for A +A →0 . In the thermodynamic limit with a finite density of walls, coarsening as a function of time t is studied by simulation. While the number of walls falls as t-1/2, the fraction of persistent arrowheads decays as t-θ where θ is close to 1/4 , quite different from the Ising value. The global persistence too has θ =1/4 , as follows from a heuristic argument. In a generalization where the B walls diffuse slowly, θ varies continuously, increasing with increasing diffusion constant.

  20. Large-scale three-dimensional phase-field simulations for phase coarsening at ultrahigh volume fraction on high-performance architectures

    Science.gov (United States)

    Yan, Hui; Wang, K. G.; Jones, Jim E.

    2016-06-01

    A parallel algorithm for large-scale three-dimensional phase-field simulations of phase coarsening is developed and implemented on high-performance architectures. From the large-scale simulations, a new kinetics in phase coarsening in the region of ultrahigh volume fraction is found. The parallel implementation is capable of harnessing the greater computer power available from high-performance architectures. The parallelized code enables increase in three-dimensional simulation system size up to a 5123 grid cube. Through the parallelized code, practical runtime can be achieved for three-dimensional large-scale simulations, and the statistical significance of the results from these high resolution parallel simulations are greatly improved over those obtainable from serial simulations. A detailed performance analysis on speed-up and scalability is presented, showing good scalability which improves with increasing problem size. In addition, a model for prediction of runtime is developed, which shows a good agreement with actual run time from numerical tests.

  1. Mid-infrared nonlinear silicon photonics

    Science.gov (United States)

    Liu, Xiaoping; Kuyken, Bart; Green, William M. J.; Osgood, Richard M.; Baets, Roel; Roelkens, Gunther

    2014-03-01

    Recently there has been a growing interest in mid-infrared (mid-IR) photonic technology with a wavelength of operation approximately from 2-14 μm. Among several established mid-IR photonic platforms, silicon nanophotonic platform could potentially offer ultra-compact, and monolithically integrated mid-IR photonic devices and device arrays, which could have board impact in the mid-IR technology, such as molecular spectroscopy, and imaging. At room temperature, silicon has a bandgap ~ 1.12 eV resulting in vanishing two-photon absorption (TPA) for mid-IR wavelengths beyond 2.2 μm, which, coupled with silicon's large nonlinear index of refraction and its strong waveguide optical confinement, enables efficient nonlinear processes in the mid-IR. By taking advantage of these nonlinear processes and judicious dispersion engineering in silicon waveguides, we have recently demonstrated a handful of silicon mid-IR nonlinear components, including optical parametric amplifiers (OPA), broadband sources, and a wavelength translator. Silicon nanophotonic waveguide's anomalous dispersion design, providing four-wave-mixing (FWM) phase-matching, has enabled the first demonstration of silicon mid-IR optical parametric amplifier (OPA) with a net off-chip gain exceeding 13 dB. In addition, reduction of propagation losses and balanced second and fourth order waveguide dispersion design led to an OPA with an extremely broadband gain spectrum from 1.9-2.5 μm and >50 dB parametric gain, upon which several novel silicon mid-IR light sources were built, including a mid-IR optical parametric oscillator, and a supercontinuum source. Finally, a mid-IR wavelength translation device, capable of translating signals near 2.4 μm to the telecom-band near 1.6 μm with simultaneous 19 dB gain, was demonstrated.

  2. On the Nonlinear Evolution of Cosmic Web: Lagrangian Dynamics Revisited

    CERN Document Server

    Wang, Xin

    2014-01-01

    We investigate the nonlinear evolution of cosmic morphologies of the large-scale structure by examining the Lagrangian dynamics of various tensors of a cosmic fluid element, including the velocity gradient tensor, the Hessian matrix of the gravitational potential as well as the deformation tensor. Instead of the eigenvalue representation, the first two tensors, which associate with the "kinematic" and "dynamical" cosmic web classification algorithm respectively, are studied in a more convenient parameter space. These parameters are defined as the rotational invariant coefficients of the characteristic equation of the tensor. In the nonlinear local model (NLM) where the magnetic part of Weyl tensor vanishes, these invariants are fully capable of characterizing the dynamics. Unlike the Zeldovich approximation (ZA), where various morphologies do not change before approaching a one-dimensional singularity, the sheets in NLM are unstable for both overdense and underdense perturbations. While it has long been known...

  3. Riemann-Cartan geometry of nonlinear disclination mechanics

    KAUST Repository

    Yavari, A.

    2012-03-23

    In the continuous theory of defects in nonlinear elastic solids, it is known that a distribution of disclinations leads, in general, to a non-trivial residual stress field. To study this problem, we consider the particular case of determining the residual stress field of a cylindrically symmetric distribution of parallel wedge disclinations. We first use the tools of differential geometry to construct a Riemannian material manifold in which the body is stress-free. This manifold is metric compatible, has zero torsion, but has non-vanishing curvature. The problem then reduces to embedding this manifold in Euclidean 3-space following the procedure of a classical nonlinear elastic problem. We show that this embedding can be elegantly accomplished by using Cartan\\'s method of moving frames and compute explicitly the residual stress field for various distributions in the case of a neo-Hookean material. © 2012 The Author(s).

  4. Off-shell BCJ Relation in Nonlinear Sigma Model

    CERN Document Server

    Chen, Gang; Liu, Hanqing

    2016-01-01

    We investigate relations among tree-level off-shell currents in nonlinear sigma model. Under Cayley parametrization, we propose and prove a general revised BCJ relation for even-point currents. Unlike the on-shell BCJ relation, the off-shell one behaves quite differently from Yang-Mills theory although the algebraic structure is the same. After performing the permutation summation in the revised BCJ relation, the sum is non-vanishing, instead, it equals to the sum of sub-current products with the BCJ coefficients under a specific ordering, which is presented by an explicit formula. Taking on-shell limit, this identity is reduced to the on-shell BCJ relation, and thus provides the full off-shell correspondence of tree-level BCJ relation in nonlinear sigma model.

  5. NONLINEAR EXPECTATIONS AND NONLINEAR MARKOV CHAINS

    Institute of Scientific and Technical Information of China (English)

    PENG SHIGE

    2005-01-01

    This paper deals with nonlinear expectations. The author obtains a nonlinear generalization of the well-known Kolmogorov's consistent theorem and then use it to construct filtration-consistent nonlinear expectations via nonlinear Markov chains. Compared to the author's previous results, i.e., the theory of g-expectations introduced via BSDE on a probability space, the present framework is not based on a given probability measure. Many fully nonlinear and singular situations are covered. The induced topology is a natural generalization of Lp-norms and L∞-norm in linear situations.The author also obtains the existence and uniqueness result of BSDE under this new framework and develops a nonlinear type of von Neumann-Morgenstern representation theorem to utilities and present dynamic risk measures.

  6. Nonlinearly Coupled Superconducting Lumped Element Resonators

    Science.gov (United States)

    Collodo, Michele C.; Potočnik, Anton; Rubio Abadal, Antonio; Mondal, Mintu; Oppliger, Markus; Wallraff, Andreas

    We study SQUID-mediated tunable coupling between two superconducting on-chip resonators in the microwave frequency range. In this circuit QED implementation, we employ lumped-element type resonators, which consist of Nb thin film structured into interdigitated finger shunt capacitors and meander inductors. A SQUID, functioning as flux dependent and intrinsically nonlinear inductor, is placed as a coupling element together with an interdigitated capacitor between the two resonators (cf. A. Baust et al., Phys Rev. B 91 014515 (2015)). We perform a spectroscopic measurement in a dilution refrigerator and find the linear photon hopping rate between the resonators to be widely tunable as well as suppressible for an appropriate choice of parameters, which is made possible due to the interplay of inductively and capacitively mediated coupling. Vanishing linear coupling promotes nonlinear effects ranging from onsite- to cross-Kerr interaction. A dominating cross-Kerr interaction related to this configuration is notable, as it induces a unique quantum state. In the course of analog quantum simulations, such elementary building blocks can serve as a precursor for more complex geometries and thus pave the way to a number of novel quantum phases of light

  7. Extended Lagrangian Born-Oppenheimer molecular dynamics in the limit of vanishing self-consistent field optimization.

    Science.gov (United States)

    Souvatzis, Petros; Niklasson, Anders M N

    2013-12-07

    We present an efficient general approach to first principles molecular dynamics simulations based on extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The reduction of the optimization requirement reduces the computational cost to a minimum, but without causing any significant loss of accuracy or long-term energy drift. The optimization-free first principles molecular dynamics requires only one single diagonalization per time step, but is still able to provide trajectories at the same level of accuracy as "exact," fully converged, Born-Oppenheimer molecular dynamics simulations. The optimization-free limit of extended Lagrangian Born-Oppenheimer molecular dynamics therefore represents an ideal starting point for robust and efficient first principles quantum mechanical molecular dynamics simulations.

  8. Silicon-on-insulator 1×2 Y-junction Optical Switch Based on Waveguide-vanishing Effect①②

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    The silicon-on-insulator(SOI)1×2Y-junction optical waveguide switch has been proposed and fabricated,which is based on the large cross-section single-mode rib waveguide condition,the waveguide-vanishing effect and the free-carrier plasma dispersion effect.In the switch,the SOI technique utilizer silicon and silicon dioxide thermal bonding and back-polishing.The insertion loss and extinction ratio of the device are measured to be less than 4.78dB and 20.8dB respectively at a wavelength of 1.3μm and an injection current of 45mA.Response time is about 160ns.

  9. Super-mercuryphobic and hydrophobic diamond surfaces with hierarchical structures: Vanishment of the contact angle hysteresis with mercury

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, Juan V., E-mail: escobar@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, PO Box 20-364, DF, México, 01000 (Mexico); Garza, Cristina, E-mail: cgarza@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, PO Box 20-364, DF, México, 01000 (Mexico); Alonso, Juan Carlos, E-mail: alonso@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, PO Box 70-360, DF, México, 04510 (Mexico); Castillo, Rolando, E-mail: rolandoc@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, PO Box 20-364, DF, México, 01000 (Mexico)

    2013-05-15

    Increased roughness is known to enhance the natural wetting properties of surfaces, making them either more hydrophobic or more hydrophilic. In this work we study the wetting properties of water and mercury drops in contact with boron doped diamond films with progressively increased surface roughnesses. We show how thermal oxidation of a microcrystalline film creates pyramids decorated with sub-micron protrusions that turn its naturally mercuryphobic surface into super-mercuryphobic. With this liquid, we observe the vanishment of the contact angle hysteresis that is expected for rough surfaces as the contact angle approaches 180, making small drops of mercury roll along out of the surface at an apparent zero tilt-angle. In contrast, the incorporation of nano-globules on the oxidized surface through a silanization process is necessary to increase the hydrophobic properties of the film for which the contact angle with water reaches 138°. The wetting states that dominate in each case are discussed.

  10. Super-mercuryphobic and hydrophobic diamond surfaces with hierarchical structures: Vanishment of the contact angle hysteresis with mercury

    Science.gov (United States)

    Escobar, Juan V.; Garza, Cristina; Alonso, Juan Carlos; Castillo, Rolando

    2013-05-01

    Increased roughness is known to enhance the natural wetting properties of surfaces, making them either more hydrophobic or more hydrophilic. In this work we study the wetting properties of water and mercury drops in contact with boron doped diamond films with progressively increased surface roughnesses. We show how thermal oxidation of a microcrystalline film creates pyramids decorated with sub-micron protrusions that turn its naturally mercuryphobic surface into super-mercuryphobic. With this liquid, we observe the vanishment of the contact angle hysteresis that is expected for rough surfaces as the contact angle approaches 180˚, making small drops of mercury roll along out of the surface at an apparent zero tilt-angle. In contrast, the incorporation of nano-globules on the oxidized surface through a silanization process is necessary to increase the hydrophobic properties of the film for which the contact angle with water reaches 138°. The wetting states that dominate in each case are discussed.

  11. Adult-onset vanishing white matter disease as differential diagnosis of primary progressive multiple sclerosis: a case report.

    Science.gov (United States)

    Herwerth, Marina; Schwaiger, Benedikt J; Kreiser, Kornelia; Hemmer, Bernhard; Ilg, Rüdiger

    2015-04-01

    We report the case of a 42-year-old woman with a slowly progressive cerebellar syndrome. In contrast to a relatively mild clinical presentation, the magnetic resonance imaging (MRI) showed extensive leukencephalopathy with cystic degeneration. Initially primary progressive multiple sclerosis (PPMS) was suspected. Additional diffusion-weighted imaging revealed restricted diffusion in the white matter lesions with a reduced apparent diffusion coefficient. Genetic testing showed vanishing white matter disease (VWM) with c.260C>T EIF2B3 mutation. In conclusion, in cases with relatively mild symptoms and extensive white matter lesions, adult-onset VWM should be considered as differential diagnosis of PPMS and diffusion-weighted imaging may be helpful to identify suspected cases.

  12. Existence of global strong solution and vanishing capillarity-viscosity limit in one dimension for the Korteweg system

    CERN Document Server

    Charve, Frédéric

    2011-01-01

    In the first part of this paper, we prove the existence of global strong solution for Korteweg system in one dimension. In the second part, motivated by the processes of vanishing capillarity-viscosity limit in order to select the physically relevant solutions for a hyperbolic system, we show that the global strong solution of the Korteweg system converges in the case of a $\\gamma$ law for the pressure ($P(\\rho)=a\\rho^{\\gamma}$, $\\gamma>1$) to entropic solution of the compressible Euler equations. In particular it justifies that the Korteweg system is suitable for selecting the physical solutions in the case where the Euler system is strictly hyperbolic. The problem remains open for a Van der Waals pressure because in this case the system is not strictly hyperbolic and in particular the classical theory of Lax and Glimm (see \\cite{Lax,G}) can not be used.

  13. Vanishing honey bees: Is the dying of adult worker bees a consequence of short telomeres and premature aging?

    Science.gov (United States)

    Stindl, Reinhard; Stindl, Wolfgang

    2010-10-01

    Einstein is often quoted to have said that without the bee, mankind would have but 4years to live. It is highly unlikely that he made this comment, which was even mentioned in a Lancet article on honey bees. However, the current vanishing of the bees can have serious consequences for human health, because 35% of the human diet is thought to benefit from pollination. Colony collapse disorder (CCD) in honey bees is characterized by the rapid decline of the adult bee population, leaving the brood and the queen poorly or completely unattended, with no dead bodies in or around the hive. A large study found no evidence that the presence or amount of any individual pesticide or infectious agent occurred more frequently or abundantly in CCD-affected colonies. The growing consensus is that honey bees are suffering from comprised immune systems, which allow various infectious pathogens to invade. The question remains, what causes immunosuppression in many colonies of Apis mellifera in North America and Europe? Telomeres are protective DNA structures located at eukaryotic chromosome tips that shorten in the somatic tissues of animals with age. Lifelong tissue regeneration takes place in Apis mellifera, and worker bees have been shown to senesce. In humans, a vast amount of literature has accumulated on exhausted telomere reserves causing impaired tissue regeneration and age-associated diseases, specifically cancer and immunosuppression. Therefore, we propose a new causative mechanism for the vanishing of the bees: critically short telomeres in long-lived winter bees. We term this the telomere premature aging syndrome. Copyright 2010 Elsevier Ltd. All rights reserved.

  14. Cogenesis in a universe with vanishing B–L within a gauged U(1){sub x} extension

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Wan-Zhe, E-mail: vicf@mpp.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), 80805 München (Germany); Nath, Pran, E-mail: nath@neu.edu [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2014-04-04

    We consider a gauged U(1){sub x} extension of the standard model and of the minimal supersymmetric standard model where the dark matter fields are charged under U(1){sub x} and carry lepton number while the standard model fields and fields of the minimal supersymmetric standard model are neutral under U(1){sub x}. We consider leptogenesis in this class of models with all fundamental interactions having no violation of lepton number, and the total B–L in the universe vanishes. Such leptogenesis leads to equal and opposite lepton numbers in the visible sector and in the dark sector, and thus also produces asymmetric dark matter. Part of the lepton number generated in the leptonic sector subsequently transfer to the baryonic sector via sphaleron interactions. The stability of the dark particles is protected by the U(1){sub x} gauge symmetry. A kinetic mixing between the U(1){sub x} and the U(1){sub Y} gauge bosons allows for dissipation of the symmetric component of dark matter. The case when U(1){sub x} is U(1){sub B–L} is also discussed for the supersymmetric case. This case is particularly interesting in that we have a gauged U(1){sub B–L} which ensures the conservation of B–L with an initial condition of a vanishing B–L in the universe. Phenomenological implications of the proposed extensions are discussed, which includes implications for electroweak physics, neutrino masses and mixings, and lepton flavor changing processes such as ℓ{sub i}→ℓ{sub j}γ. We also briefly discuss the direct detection of the dark matter in the model.

  15. The effect of a 'vanishing twin' on biochemical and ultrasound first trimester screening markers for Down's syndrome in pregnancies conceived by assisted reproductive technology

    DEFF Research Database (Denmark)

    Gjerris, A C; Loft, A; Pinborg, Anja

    2008-01-01

    . The presence of a perished embryo may further complicate prenatal screening among women pregnant after ART. The aim of this study was to assess the impact of a 'vanishing twin' on first trimester combined biochemical and ultrasound screening in pregnancies conceived after IVF and intracytoplasmatic sperm...... injection. METHODS: From a national prospective cohort study concerning first trimester combined screening among women pregnant after ART, 56 cases of pregnancies with a vanishing twin were identified. As control group 897 cases of ART singleton pregnancies were used. All women completed a first trimester......) or late vanishing twin (gestational week 9-13, LVT) or singleton pregnancies (0.98, 1.13 and 0.95 for free beta-hCG and 0.84, 0.80 and 0.74 for PAPP-A, respectively). Likewise, no difference was seen for NT measurements. The gestational age at the time of blood sampling and NT scan was similar...

  16. Nucleation, growth and coarsening of {gamma}'-precipitates in a Ni-Cr-Al-based commercial superalloy during artificial aging

    Energy Technology Data Exchange (ETDEWEB)

    Picasso, A. [Instituto de Fisica de Materiales Tandil, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, B7000GHG, Tandil (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (Argentina); Somoza, A. [Instituto de Fisica de Materiales Tandil, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, B7000GHG, Tandil (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (Argentina)], E-mail: asomoza@exa.unicen.edu.ar; Tolley, A. [Centro Atomico Bariloche, Comision Nacional de Energia Atomica, and CONICET, Avda. Bustillo 9500, R8400AGQ, San Carlos de Bariloche (Argentina)

    2009-06-24

    A study of the decomposition kinetics of the IN-X750 Ni-based superalloy using positron annihilation lifetime spectroscopy (PALS), microhardness and transmission electron microscopy (TEM) is presented. PALS results confirmed that nucleation and growth of {gamma}'-precipitates are assisted by vacancies. Due to the high sensitivity of positrons for vacancy-like defects, information regarding vacancy-solute clusters formed during the very early stages of aging was obtained. The positron lifetime and TEM results were analyzed following classical precipitation models to interpret the kinetics of the {gamma}'-precipitate formation. Finally, from TEM measurements a value of the {gamma}'-precipitate coarsening rate for the alloy studied was obtained.

  17. Advances in nonlinear optics

    CERN Document Server

    Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong

    2015-01-01

    This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.

  18. Distributed nonlinear optical response

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov

    2005-01-01

    The purpose of the research presented here is to investigate basic physical properties in nonlinear optical materials with delayed or nonlocal nonlinearity. Soliton propagation, spectral broadening and the influence of the nonlocality or delay of the nonlinearity are the main focusses in the work...

  19. Noncommutative Nonlinear Supersymmetry

    CERN Document Server

    Nishino, H; Nishino, Hitoshi; Rajpoot, Subhash

    2002-01-01

    We present noncommutative nonlinear supersymmetric theories. The first example is a non-polynomial Akulov-Volkov-type lagrangian with noncommutative nonlinear global supersymmetry in arbitrary space-time dimensions. The second example is the generalization of this lagrangian to Dirac-Born-Infeld lagrangian with nonlinear supersymmetry realized in dimensions D=2,3,4 and 6 (mod 8).

  20. Fiber Nonlinearities: A Tutorial

    Institute of Scientific and Technical Information of China (English)

    Govind P. Agrawal

    2003-01-01

    Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications,the Raman amplification being only one of the recent examples. In this tutorial I review the vario us nonlinear effects occurring in optical fibers from both standpoints..

  1. Fiber Nonlinearities: A Tutorial

    Institute of Scientific and Technical Information of China (English)

    Govind; P.; Agrawal

    2003-01-01

    Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications, the Raman amplification being only one of the recent examples. In this tutorial I review the various nonlinear effects occurring in optical fibers from both standpoints..

  2. PBH tests for nonlinear systems

    NARCIS (Netherlands)

    Kawano, Yu; Ohtsuka, Toshiyuki

    2017-01-01

    Recently, concepts of nonlinear eigenvalues and eigenvectors are introduced. In this paper, we establish connections between the nonlinear eigenvalues and nonlinear accessibility/observability. In particular, we provide a generalization of Popov- Belevitch-Hautus (PBH) test to nonlinear accessibilit

  3. Extension to nonlinear stability theory of the circular Couette flow

    Science.gov (United States)

    Yau, Pun Wong; Wang, Shixiao; Rusak, Zvi

    2016-11-01

    A nonlinear stability analysis of the viscous circular Couette flow to axisymmetric perturbations under axial periodic boundary conditions is developed. The analysis is based on investigating the properties of a reduced Arnol'd energy-Casimir function Ard of Wang (2009). We show that all the inviscid flow effects as well as all the viscous-dependent terms related to the flow boundaries vanish. The evolution of ΔArd depends solely on the viscous effects of the perturbation's dynamics inside the flow domain. The requirement for the temporal decay of ΔArd leads to novel sufficient conditions for the nonlinear stability of the circular Couette flow in response to axisymmetric perturbations. Comparisons with historical studies show that our results shed light on the experimental measurements of Wendt (1933) and significantly extend the classical nonlinear stability results of Serrin (1959) and Joseph & Hung (1971). When the flow is nonlinearly stable and evolves axisymmetrically for all time, then it always decays asymptotically in time to the circular Couette flow determined uniquely by the setup of the rotating cylinders. This study provides new physical insights into a classical flow problem that was studied for decades.

  4. Nonlinear dynamics and complexity

    CERN Document Server

    Luo, Albert; Fu, Xilin

    2014-01-01

    This important collection presents recent advances in nonlinear dynamics including analytical solutions, chaos in Hamiltonian systems, time-delay, uncertainty, and bio-network dynamics. Nonlinear Dynamics and Complexity equips readers to appreciate this increasingly main-stream approach to understanding complex phenomena in nonlinear systems as they are examined in a broad array of disciplines. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering.

  5. Bilateral vanished testes diagnosed with a single blood sample showing very high gonadotropins (follicle-stimulating hormone and luteinizing hormone) and very low inhibin B

    DEFF Research Database (Denmark)

    Thorup, Jørgen Mogens; Petersen, Bodil Laub; Kvist, Kolja

    2011-01-01

    . The aim of the study was to evaluate whether a simple blood sample of gonadotropins and inhibin B could diagnose bilateral vanished testes. Material and methods. Group I included five boys (4 months to 6 years and 3 months old) with bilateral vanished testes at laparoscopy. Group II included 82 boys...... with bilateral cryptorchidism younger than 7 years of age at surgery for bilateral cryptorchidism (median age 1 year and 9 months). Results. The serum levels of hormones for the patients with vanished testes were: inhibin B 5-18 pg/ml, FSH 41-191 IU/l and LH 3.9-56 IU/l. The patients all had karyotype 46,xy....... The serum levels of hormones from group II were: inhibin B median 122 (range 20-404) pg/ml, FSH median 0.8 (range 0.2-3.5) IU/l and LH median 0.2 (range 0.1-3.2) IU/l. The serum levels of inhibin B, FSH and LH from the boys with vanished testes were significantly different from the serum levels of the boys...

  6. Vanishing electron g factor and long-lived nuclear spin polarization in weakly strained nanohole-filled GaAs/AlGaAs quantum dots

    OpenAIRE

    Ulhaq, A.; Duan, Q; Zallo, E.; Ding, F.; Schmidt, O. G.; Tartakovskii, A. I.; Skolnick, M. S.; Chekhovich, E. A.

    2016-01-01

    GaAs/AlGaAs quantum dots grown by in situ droplet etching and nanohole in-filling offer a combination of strong charge confinement, optical efficiency, and high spatial symmetry advantageous for polarization entanglement and spin-photon interface. Here, we study experimentally electron and nuclear spin properties of such dots. We find nearly vanishing electron g factors (ge

  7. Phantom Vanish magic trick: Investigating the disappearance of a non-existent object in a dynamic scene.

    Directory of Open Access Journals (Sweden)

    Matthew L Tompkins

    2016-07-01

    Full Text Available Drawing inspiration from sleight-of-hand magic tricks, we developed an experimental paradigm to investigate whether magicians’ misdirection techniques could be used to induce the misperception of ‘phantom’ objects. While previous experiments investigating sleight-of-hand magic tricks have focused on creating false assumptions about the movement of an object in a scene, our experiment investigated creating false assumptions about the presence of an object in a scene. Participants watched a sequence of silent videos depicting a magician performing with a single object. Following each video, participants were asked to write a description of the events in the video. In the final video, participants watched the Phantom Vanish Magic Trick, a novel magic trick developed for this experiment, in which the magician pantomimed the actions of presenting an object and then making it magically disappear. No object was presented during the final video. The silent videos precluded the use of false verbal suggestions, and participants were not asked leading questions about the objects. Nevertheless, 32% of participants reported having visual impressions of non-existent objects. These findings support an inferential model of perception, wherein top-down expectations can be manipulated by the magician to generate vivid illusory experiences, even in the absence of corresponding bottom-up information.

  8. Nakedness and curvature strength of shell-focusing singularity in the spherically symmetric space-time with vanishing radial pressure

    CERN Document Server

    Harada, T; Iguchi, H; Harada, Tomohiro; Nakao, Ken-ichi; Iguchi, Hideo

    1999-01-01

    It was recently shown that the metric functions which describe a spherically symmetric space-time with vanishing radial pressure can be explicitly integrated. We investigate the nakedness and curvature strength of the shell-focusing singularity in that space-time. If the singularity is naked, the relation between the circumferential radius and the Misner-Sharp mass is given by $R\\approx 2y_{0} m^{\\beta}$ with $ 1/3<\\beta\\le 1$ along the first radial null geodesic from the singularity. The $\\beta$ is closely related to the curvature strength of the naked singularity. For example, for the outgoing or ingoing null geodesic, if the strong curvature condition (SCC) by Tipler holds, then $\\beta$ must be equal to 1. We define the ``gravity dominance condition'' (GDC) for a geodesic. If GDC is satisfied for the null geodesic, both SCC and the limiting focusing condition (LFC) by Królak hold for $\\beta=1$ and $y_{0}\

  9. The Phantom Vanish Magic Trick: Investigating the Disappearance of a Non-existent Object in a Dynamic Scene.

    Science.gov (United States)

    Tompkins, Matthew L; Woods, Andy T; Aimola Davies, Anne M

    2016-01-01

    Drawing inspiration from sleight-of-hand magic tricks, we developed an experimental paradigm to investigate whether magicians' misdirection techniques could be used to induce the misperception of "phantom" objects. While previous experiments investigating sleight-of-hand magic tricks have focused on creating false assumptions about the movement of an object in a scene, our experiment investigated creating false assumptions about the presence of an object in a scene. Participants watched a sequence of silent videos depicting a magician performing with a single object. Following each video, participants were asked to write a description of the events in the video. In the final video, participants watched the Phantom Vanish Magic Trick, a novel magic trick developed for this experiment, in which the magician pantomimed the actions of presenting an object and then making it magically disappear. No object was presented during the final video. The silent videos precluded the use of false verbal suggestions, and participants were not asked leading questions about the objects. Nevertheless, 32% of participants reported having visual impressions of non-existent objects. These findings support an inferential model of perception, wherein top-down expectations can be manipulated by the magician to generate vivid illusory experiences, even in the absence of corresponding bottom-up information.

  10. How Cooper pairs vanish approaching the Mott insulator in Bi2Sr2CaCu2O8+delta.

    Science.gov (United States)

    Kohsaka, Y; Taylor, C; Wahl, P; Schmidt, A; Lee, Jhinhwan; Fujita, K; Alldredge, J W; McElroy, K; Lee, Jinho; Eisaki, H; Uchida, S; Lee, D-H; Davis, J C

    2008-08-28

    The antiferromagnetic ground state of copper oxide Mott insulators is achieved by localizing an electron at each copper atom in real space (r-space). Removing a small fraction of these electrons (hole doping) transforms this system into a superconducting fluid of delocalized Cooper pairs in momentum space (k-space). During this transformation, two distinctive classes of electronic excitations appear. At high energies, the mysterious 'pseudogap' excitations are found, whereas, at lower energies, Bogoliubov quasi-particles-the excitations resulting from the breaking of Cooper pairs-should exist. To explore this transformation, and to identify the two excitation types, we have imaged the electronic structure of Bi(2)Sr(2)CaCu(2)O(8+delta) in r-space and k-space simultaneously. We find that although the low-energy excitations are indeed Bogoliubov quasi-particles, they occupy only a restricted region of k-space that shrinks rapidly with diminishing hole density. Concomitantly, spectral weight is transferred to higher energy r-space states that lack the characteristics of excitations from delocalized Cooper pairs. Instead, these states break translational and rotational symmetries locally at the atomic scale in an energy-independent way. We demonstrate that these unusual r-space excitations are, in fact, the pseudogap states. Thus, as the Mott insulating state is approached by decreasing the hole density, the delocalized Cooper pairs vanish from k-space, to be replaced by locally translational- and rotational-symmetry-breaking pseudogap states in r-space.

  11. Chiral phase transition of $N_f$=2+1 and 3 QCD at vanishing baryon chemical potential

    CERN Document Server

    Ding, Heng-Tong

    2015-01-01

    We present updated results on chiral phase structure in (2+1)-flavor ($N_f$=2+1) and 3-flavor ($N_f=3$) QCD based on the simulations using Highly Improved Staggered Quarks on lattices with temporal extent $N_\\tau$ =6 at vanishing baryon chemical potential. In $N_f$=2+1 QCD we have performed simulations with a strange quark fixed to its physical value and two degenerate light quarks whose values are adjusted to have 5 values of Goldstone pion masses in the region of 160 - 80 MeV in the continuum limit. The universal scaling behavior of chiral condensates as well as chiral susceptibilities is discussed and the tri-critical point is suggested to be located below the physical point, i.e. at smaller than physical strange quark mass. In $N_f$=3 QCD simulations with 6 different masses of 3 degenerate quarks corresponding to the Goldstone pion masses in the region of 230 - 80 MeV have also been performed. Our results suggest that the QCD transition with these values of quark masses is of crossover type and an upper b...

  12. Fetal Aneuploidy Detection by Cell-Free DNA Sequencing for Multiple Pregnancies and Quality Issues with Vanishing Twins

    Directory of Open Access Journals (Sweden)

    Sebastian Grömminger

    2014-06-01

    Full Text Available Non-invasive prenatal testing (NIPT by random massively parallel sequencing of maternal plasma DNA for multiple pregnancies is a promising new option for prenatal care since conventional non-invasive screening for fetal trisomies 21, 18 and 13 has limitations and invasive diagnostic methods bear a higher risk for procedure related fetal losses in the case of multiple gestations compared to singletons. In this study, in a retrospective blinded analysis of stored twin samples, all 16 samples have been determined correctly, with four trisomy 21 positive and 12 trisomy negative samples. In the prospective part of the study, 40 blood samples from women with multiple pregnancies have been analyzed (two triplets and 38 twins, with two correctly identified trisomy 21 cases, confirmed by karyotyping. The remaining 38 samples, including the two triplet pregnancies, had trisomy negative results. However, NIPT is also prone to quality issues in case of multiple gestations: the minimum total amount of cell-free fetal DNA must be higher to reach a comparable sensitivity and vanishing twins may cause results that do not represent the genetics of the living sibling, as described in two case reports.

  13. Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

    Indian Academy of Sciences (India)

    Antonella Fiacca; Nikolaos Matzakos; Nikolaos S Papageorgiou; Raffaella Servadei

    2001-11-01

    In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all $\\mathbb{R}$. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of $\\mathbb{R}$. This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).

  14. Vanishing Financial Contagion?

    OpenAIRE

    Didier, Tatiana; Mauro, Paolo; Schmukler, Sergio L.

    2008-01-01

    While a number of crises in emerging markets generated widespread contagion in financial markets during the 1990s, more recent crises (notably, in Argentina) have been mostly contained within national borders. This has led some observers to wonder whether contagion might have become a feature of the past, with financial markets now better discriminating between emerging countries with good and bad fundamentals. Available data suggest that the main channels that contribute to transmitting fina...

  15. The Vanishing Universe

    Science.gov (United States)

    McNally, Derek

    1994-09-01

    Introduction - the effect of civilisation on observational astronomy D. McNally; 1. The frontiers of modern astronomy M. S. Longair; 2. The aims of astronomy in science and the humanities: why astronomy must be protected P. Murdin; 3. General principles of the right to uninterrupted activities in outer space B. Reijen; 4. Light pollution - theft of the night D. L. Crawford; 5. Impact and restriction of interference of light D. A. Schreudre; 6. Adverse environmental impacts on astronomy: the case of improved street lighting D. T. Herbert; 7. Light extinction in the atmosphere N. Laulainen; 8. Environmental effects on astronomical observation J. Kovalevsky; 9. Natural background radiation: the light from the night sky A. C. Levasseur-Regourd; 10. Opening the radio window F. Graham-Smith; 11. The threat to radio astronomy J. B. Whiteoak; 12. Radio interference to passive scientific measurements: its causes and its cures R. M. Price; 13. Radio astronomy in the radio environment C. Kirby and R. G. Struzak; 14. Preserving wilderness areas in the radio spectrum P. A. Vanden Bout; 15. Illustration of radio interference D. McNally; 16. mm-Wave - the last virgin land M. Morimoto; 17. The Mount Wilson story M. Bester, S. Baliunas, C. Shelton and L. Webster; 18. Radio astronomy and the developing countries G. Swarup; 19. The disappearance of the night sky D. Malin; 20. The space debris environment of the earth W. Flury; 21. Space debris observations: needs for new technology Y. Arimoto; 22. Illustration of the effects of space debris D. McNalley; 23. Space debris: how to improve the situation L. Perek.

  16. Is librarianship vanishing?

    Directory of Open Access Journals (Sweden)

    Jadranka Lasić-Lazić

    1997-01-01

    Full Text Available The role of librarianship in the information age has been a subject of many research papers. This particular one raises several questions about the influence of changes in society, in use of technology, and in science of librarianship as a profession. The results of these changes have created room for the broadening of the content and the aim of librarianship as much as they have questioned librarian's ability to succeed in his new information specialisfs role. The last issue covered by this paper refers to the notion about the importance of continuous professional education in librarianship on ali levels which represents the foundation of the very same profession.The second part of the paper refers to the changes in the course of education itself.The goal of education has changed and today it demands from a young person the ability not only to qualify for the job but also to be able and prepared for independent learning, professional improvement and creative thinking imposed by the fast technological changes which are usually faster than those which occur in the process of education. The speed of these changes can be best illustrated by the example of current generations who are finishing their education lacking knowledge of the use of new technologies.Therefore, it is the task of every expert and our profession as a community to satisfy the need for the improvement in the profession and to ensure its survival and progress.Another important issue is the vocation-profession distinction among librarians and their double role. On one side, they are information specialists and librarians and on the other side, they are also educationalists which are either directly involved in the course of education as school librarians or are those who make and mediate information and knowledge necessary for other people's education.In order to last and participate in the development of society as a community and mankind in general, librarianship needs to continuously query itself and logically merge new information technologies with the traditional approach to librarians as information mediators. The division of library sections is more and more based on physical and intellectual approach to information and it can be taken as an example of afore mentioned new concept. This change of Iibrary structure is adequate for electronic and virtual environments which demand greater adaptability,direct communication and more informationexchange. With the occurrence of the Internet, libraries have got a new opportunity to become important factors in the course of education and in the development of society and science in general and librarians have got some new tasks to accomplish and some new roles to prepare themselves for.

  17. A Vanishing Act

    DEFF Research Database (Denmark)

    la Cour, Anders; Hecht, Janus; Stilling, Maria Kirstine

    2016-01-01

    The use of information and communication technology (ICT) has played an important role in the reforms that have taken place in Western welfare societies over the past two decades. ICT is regarded as a way to provide transparency and information exchange among providers, users and politicians....... This has also been the case for healthcare services in elderly home care, where ICT has been deployed to enable information exchange, knowledge sharing and documentation of delivered services. This article explores the extent to which the popular personal digital assistant (PDA) contributes to these types...... of activities in the provision of elderly home care services in Copenhagen, Denmark. We argue that despite the PDA’s promising potential to provide increased transparency concerning the delivery of services, it has had the opposite effect. Rather than creating transparency, the PDA has become a tool for hiding...

  18. Paperless or vanishing society

    Science.gov (United States)

    Turner Luke, Joy

    2002-06-01

    In the 1940s color photography became available and within a few years, extremely popular. As people switched from black and white photographs made with the old metallic silver process to the new color films, pictures taken to record their lives and families began a slow disappearing act. The various color processes, coupled with the substrates they were printed on, affected their longevity, but many color photographs taken from the late 1950s through the 1970s, and even into the 1980s, faded not only when exposed to the light, but also when stored in the dark. Henry Wilhelm's excellent book 'The Permanence and Care of Color Photographs' documents this history in detail. Today we are making another transition in the storage of pictures and information. There are questions about the longevity of different types of digital storage, and also of the images printed by various types of inkjet printers, or by laser printers using colored toners. Very expensive and very beautiful works of art produced on Iris printers are appearing in art exhibitions. Some of these are referred to as Giclee prints and are offered on excellent papers. Artists are told the prints will last a lifetime; and if by change they don't it is only necessary to make another print. Henry Wilhelm has begun to test and rate these images for lightfastness; however, his test method was developed for examining longevity in colored photographs. It is of interest to find out how these prints will hold up in the tests required for fine art materials. Thus far companies producing digital inks and printers have not invested the time and money necessary to develop an American Society for Testing and Materials (ASTM) standard method for evaluating the lightfastness of digital prints. However, it is possible to use ASTM D 5383, Standard Practice for Visual Determination of the Lightfastness of Art Materials by Art Technologists, to pinpoint colors that will fade in a short time, even though the test is not as severe as ASTM D 4303, which is used to rate the lightfastness of artists's paint.

  19. Vanishing tumor in pregnancy

    Directory of Open Access Journals (Sweden)

    M V Vimal

    2012-01-01

    Full Text Available A patient with microprolactinoma, who had two successful pregnancies, is described for management issues. First pregnancy was uneventful. During the second pregnancy, the tumor enlarged to macroprolactinoma with headache and blurring of vision which was managed successfully with bromocriptine. Post delivery, complete disappearance of the tumor was documented.

  20. "Vanishing" pulmonary valve stenosis

    Directory of Open Access Journals (Sweden)

    Nofil I Arain

    2012-01-01

    Full Text Available Objective: Both spontaneous resolution and progression of mild pulmonary valve stenosis (PS have been reported. We reviewed characteristics of the pulmonary valve (PV to determine factors that could influence resolution of mild PS. Methods: Fifteen asymptomatic pediatric patients with spontaneous resolution of isolated mild PS were retrospectively reviewed. Results: There was no correlation between the PV gradient, clinical presentation, age at diagnosis, or PV morphology. The PV annulus was small at initial presentation, which normalized at follow up. When corrected for the body surface area (z-score, the PV annulus was normal in all patients, including at initial evaluation. Conclusions: Based on our observation, neither age at diagnosis, nor PV-morphology-influenced resolution of mild PS. The variable clinical presentation makes it difficult to categorize and observe mild PS by auscultation alone. The PV annulus z-score could be a useful adjunct to determine the course and serial observation of mild PS.

  1. On the existence of two-dimensional nonlinear steady states in plane Couette flow

    CERN Document Server

    Rincon, Francois

    2007-01-01

    The problem of two-dimensional steady nonlinear dynamics in plane Couette flow is revisited using homotopy from either plane Poiseuille flow or from plane Couette flow perturbed by a small symmetry-preserving identity operator. Our results show that it is not possible to obtain the nonlinear plane Couette flow solutions reported by Cherhabili and Ehrenstein [Eur. J. Mech. B/Fluids, 14, 667 (1995)] using their Poiseuille-Couette homotopy. We also demonstrate that the steady solutions obtained by Mehta and Healey [Phys. Fluids, 17, 4108 (2005)] for small symmetry-preserving perturbations are influenced by an artefact of the modified system of equations used in their paper. However, using a modified version of their model does not help to find plane Couette flow solution in the limit of vanishing symmetry-preserving perturbations either. The issue of the existence of two-dimensional nonlinear steady states in plane Couette flow remains unsettled.

  2. Some current topics on nonlinear conservation laws lectures at the morningside center of mathematics, 1

    CERN Document Server

    Hsiao, Ling

    2000-01-01

    This volume resulted from a year-long program at the Morningside Center of Mathematics at the Academia Sinica in Beijing. It presents an overview of nonlinear conversation laws and introduces developments in this expanding field. Xin's introductory overview of the subject is followed by lecture notes of leading experts who have made fundamental contributions to this field of research. A. Bressan's theory of L^1-well-posedness for entropy weak solutions to systems of nonlinear hyperbolic conversation laws in the class of viscosity solutions is one of the most important results in the past two decades; G. Chen discusses weak convergence methods and various applications to many problems; P. Degond details mathematical modelling of semi-conductor devices; B. Perthame describes the theory of asymptotic equivalence between conservation laws and singular kinetic equations; Z. Xin outlines the recent development of the vanishing viscosity problem and nonlinear stability of elementary wave-a major focus of research in...

  3. Geometrothermodynamics of black holes in Lovelock gravity with a nonlinear electrodynamics

    Science.gov (United States)

    Hendi, S. H.; Naderi, R.

    2015-01-01

    The objective of the present paper is to analyze the phase transition of asymptotically anti-de Sitter (AdS) black-hole solutions in Lovelock gravity in the presence of nonlinear electrodynamics. First, we present the asymptotically AdS black-hole solutions for two classes of the Born-Infeld type of nonlinear electrodynamics coupled (separately) with Einstein, Gauss-Bonnet, and third-order Lovelock gravity. Then, in order to discuss the phase transition, we calculate both the heat capacity and the Ricci scalar of the thermodynamical line element. We present a comparison between the singular points of the Ricci scalar using the geometrothermodynamics method and the corresponding vanishing points of the heat capacity in the canonical ensemble. In addition, we discuss the effects of both Lovelock and nonlinear electrodynamics on the phase transition points.

  4. Geometrothermodynamics of black holes in Lovelock gravity with a nonlinear electrodynamics

    CERN Document Server

    Hendi, Seyed Hossein

    2015-01-01

    The objective of the present paper is to analyze the phase transition of asymptotically anti-de Sitter (AdS) black hole solutions in Lovelock gravity in the presence of nonlinear electrodynamics. First, we present the asymptotically AdS black hole solutions for two classes of the Born-Infeld type of nonlinear electrodynamics coupled with Einstein, Gauss-Bonnet and third order Lovelock gravity, separately. Then, in order to discuss the phase transition, we calculate both the heat capacity and the Ricci scalar of the thermodynamical line element. We present a comparison between the singular points of the Ricci scalar using Geometrothermodynamics method and the corresponding vanishing points of the heat capacity in the canonical ensemble. In addition, we discuss the effects of both Lovelock and nonlinear electrodynamics on the phase transition points.

  5. Output feedback stabilization for stochastic nonlinear systems in observer canonical form with stable zero-dynamics

    Institute of Scientific and Technical Information of China (English)

    潘子刚; 刘允刚; 施颂椒

    2001-01-01

    In this paper, we study the problem of output feedback stabilization for stochastic nonlinear systems. We consider a class of stochastic nonlinear systems in observer canonical form with stable zero-dynamics. We introduce a sequence of state transformations that transform the system into a lower triangular structure that is amenable for integrator backstepping design. Then we design the output-feedback controller and prove that the closed-loop system is bounded in probability. Furthermore, when the disturbance vector field vanishes at the origin, the closed-loop system is asymptotically stable in the large. With special care, the controller preserves the equilibrium of the nonlinear system. An example is included to illustrate the theoretical findings.

  6. Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region.

    Science.gov (United States)

    Alam, M Zahirul; De Leon, Israel; Boyd, Robert W

    2016-05-13

    Nonlinear optical phenomena are crucial for a broad range of applications, such as microscopy, all-optical data processing, and quantum information. However, materials usually exhibit a weak optical nonlinearity even under intense coherent illumination. We report that indium tin oxide can acquire an ultrafast and large intensity-dependent refractive index in the region of the spectrum where the real part of its permittivity vanishes. We observe a change in the real part of the refractive index of 0.72 ± 0.025, corresponding to 170% of the linear refractive index. This change in refractive index is reversible with a recovery time of about 360 femtoseconds. Our results offer the possibility of designing material structures with large ultrafast nonlinearity for applications in nanophotonics. Copyright © 2016, American Association for the Advancement of Science.

  7. Nonlinear and Perturbative Evolution of Distorted Black Holes; 2, Odd-parity Modes

    CERN Document Server

    Baker, J; Campanelli, M; Loustó, C O; Seidel, E; Takahashi, R

    2000-01-01

    We compare the fully nonlinear and perturbative evolution of nonrotating black holes with odd-parity distortions utilizing the perturbative results to interpret the nonlinear results. This introduction of the second polarization (odd-parity) mode of the system, and the systematic use of combined techniques brings us closer to the goal of studying more complicated systems like distorted, rotating black holes, such as those formed in the final inspiral stage of two black holes. The nonlinear evolutions are performed with the 3D parallel code for Numerical Relativity, {Cactus}, and an independent axisymmetric code, {Magor}. The linearized calculation is performed in two ways: (a) We treat the system as a metric perturbation on Schwarzschild, using the Regge-Wheeler equation to obtain the waveforms produced. (b) We treat the system as a curvature perturbation of a Kerr black hole (but here restricted to the case of vanishing rotation parameter a) and evolve it with the Teukolsky equation The comparisons of the wa...

  8. Nonlinear Dirac Equations

    Directory of Open Access Journals (Sweden)

    Wei Khim Ng

    2009-02-01

    Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.

  9. Nonlinear viscosity derived by means of Grad's moment method

    Science.gov (United States)

    Eu, Byung Chan

    2002-03-01

    In this paper we examine the stress tensor component evolution equations recently derived by Uribe and Garcia-Colin [Phys. Rev. E 60, 4052 (1999)] for unidirectional flow at uniform temperature under the assumption/approximation of vanishing transversal velocity gradients. By removing this assumption/approximation we derive the stress tensor evolution equation from the Boltzmann equation within the framework of the Grad moment expansion for the case of uniform temperature (the same condition as theirs). Specializing the evolution equation to the case of steady unidirectional flow in a square channel, we obtain a set of steady state evolution equations for the components of the stress tensor. Because the transversal velocity gradients are not assumed to vanish in this paper in contrast to their paper, the present result is more general than theirs. Its special case corresponding to the one-dimensional flow considered by Uribe and Garcia-Colin is at variance with theirs because of a missing term in their stress evolution equation for the xy component. The nonlinear viscosity formulas are also different. A general remark is given with regard to the relation of dimensionalities of hydrodynamic equations and the kinetic equation underlying the former. They are not necessarily the same.

  10. Nonlinear Cross Gramians

    Science.gov (United States)

    Ionescu, Tudor C.; Scherpen, Jacquelien M. A.

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain linearization results that correspond to the notion of a cross Gramian for symmetric linear systems. Furthermore, first steps towards relations with the singular value functions of the nonlinear Hankel operator are studied and yield promising results.

  11. Nonlinear functional analysis

    Directory of Open Access Journals (Sweden)

    W. L. Fouché

    1983-03-01

    Full Text Available In this article we discuss some aspects of nonlinear functional analysis. It included reviews of Banach’s contraction theorem, Schauder’s fixed point theorem, globalising techniques and applications of homotopy theory to nonlinear functional analysis. The author emphasises that fundamentally new ideas are required in order to achieve a better understanding of phenomena which contain both nonlinear and definite infinite dimensional features.

  12. Nonlinear Electrodynamics and QED

    OpenAIRE

    2003-01-01

    The limits of linear electrodynamics are reviewed, and possible directions of nonlinear extension are explored. The central theme is that the qualitative character of the empirical successes of quantum electrodynamics must be used as a guide for understanding the nature of the nonlinearity of electrodynamics at the subatomic level. Some established theories of nonlinear electrodynamics, namely, those of Mie, Born, and Infeld are presented in the language of the modern geometrical and topologi...

  13. Nonlinear Physics of Plasmas

    CERN Document Server

    Kono, Mitsuo

    2010-01-01

    A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.

  14. Nonlinear magnetic metamaterials.

    Science.gov (United States)

    Shadrivov, Ilya V; Kozyrev, Alexander B; van der Weide, Daniel W; Kivshar, Yuri S

    2008-12-08

    We study experimentally nonlinear tunable magnetic metamaterials operating at microwave frequencies. We fabricate the nonlinear metamaterial composed of double split-ring resonators where a varactor diode is introduced into each resonator so that the magnetic resonance can be tuned dynamically by varying the input power. We demonstrate that at higher powers the transmission of the metamaterial becomes power-dependent and, as a result, such metamaterial can demonstrate various nonlinear properties. In particular, we study experimentally the power-dependent shift of the transmission band and demonstrate nonlinearity-induced enhancement (or suppression) of wave transmission. (c) 2008 Optical Society of America

  15. Organic nonlinear optical materials

    Science.gov (United States)

    Umegaki, S.

    1987-01-01

    Recently, it became clear that organic compounds with delocalized pi electrons show a great nonlinear optical response. Especially, secondary nonlinear optical constants of more than 2 digits were often seen in the molecular level compared to the existing inorganic crystals such as LiNbO3. The crystallization was continuously tried. Organic nonlinear optical crystals have a new future as materials for use in the applied physics such as photomodulation, optical frequency transformation, opto-bistabilization, and phase conjugation optics. Organic nonlinear optical materials, e.g., urea, O2NC6H4NH2, I, II, are reviewed with 50 references.

  16. Nonlinearity-reduced interferometer

    Science.gov (United States)

    Wu, Chien-ming

    2007-12-01

    Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as the frequency mixing, polarization mixing, polarization-frequency mixing, and the ghost reflections. An interferometer having accuracy in displacement measurement of less than one-nanometer is necessary in nanometrology. To meet the requirement, the periodic nonlinearity should be less than deep sub-nanometer. In this paper, a nonlinearity-reduced interferometry has been proposed. Both the linear- and straightness-interferometer were tested. The developed interferometer demonstrated of a residual nonlinearity less than 25 pm.

  17. Intensity-only imaging with waves, restarted inverse Born series, and analysis of coarsening in polycrystalline materials

    Science.gov (United States)

    Bardsley, Patrick

    We first study the inverse problem of recovering a complex Schrodinger potential from a discrete set of measurements of the solution to the Schrodinger equation using different source terms. We solve this problem by generalizing the inverse Born series method to nonlinear mappings between Banach spaces. In this general setting, we show convergence and stability of inverse Born series follow from a single problem-specific bound. We show this bound for the inverse Schrodinger problem, and study numerically an application of this inverse problem to transient hydraulic tomography. Additionally, we develop a family of iterative methods based on truncated inverse Born series that are akin to iterative methods based on truncated Taylor series. Next, we study the inverse problem of imaging scatterers in a homogeneous medium when only intensities of wavefields can be measured. Classic imaging methods, such as Kirchhoff migration, rely on phase information contained in full waveform data and thus cannot be used directly with intensity-only data. In situations where scattered wavefields are small compared to the incident wavefields, we can form and solve a linear least squares problem to recover a projection (on a known subspace) of full waveform data from intensity data. We show that for sufficiently high frequencies, this projection gives a Kirchhoff image asymptotically equivalent to the Kirchhoff image obtained from full waveform data. We also generalize this imaging method to using stochastic incident fields with autocorrelation measurements. Finally, we study a mathematical model of grain growth in polycrystalline materials. We review a simplified 1D grain growth model and an entropy-based theory for the evolution of an important statistic harvested from this model, the GBCD. The theory suggests the GBCD evolves according to a Fokker-Planck equation, which we validate numerically. We derive methods to estimate times from the GBCD, thus fitting it to Fokker-Planck time

  18. 消失点计算方法研究%Study of the Computational Methods of Vanishing Points

    Institute of Scientific and Technical Information of China (English)

    张政武

    2016-01-01

    利用消失点(线)进行场景理解与三维重建是计算机视觉研究中的一个重要问题。以往主要是利用图像点的齐次坐标来计算,由于同一图像点的齐次坐标之间相差一个比例因子,当图像坐标过大(或过小)时,会引起计算精度的下降。为此,从实际计算角度出发,利用图像点的坐标矢量和调和共轭特性,研究了消失点的计算方法。经过举例分析和算法验证,证明该方法实用、可靠。%The comprehensive and recognition of 3D scene by using vanishing points (lines) has been one of the most important research areas in computer vision fields. The conventional computational methods based on the image homogeneous coordinates will cause deterioration of accuracy when they become too large or too small, because the homogeneous coordinates of the same image points have different representations by the scaling factor. The computation methods by use of the characteristics of coordinates vector and harmonic range are proposed from the perspective of computational processes in this paper.The results of examples show that this algorithm is more utility and reliable than traditional algorithms.

  19. Palaeolimnological evidence of vulnerability of Lake Neusiedl (Austria) toward climate related changes since the last "vanished-lake" stage.

    Science.gov (United States)

    Tolotti, Monica; Milan, Manuela; Boscaini, Adriano; Soja, Gerhard; Herzig, Alois

    2013-04-01

    The palaeolimnological reconstruction of secular evolution of Euroepan Lakes with key socio-economical relevance respect to large (climate change) and local scale (land use, tourism) environmental changes, represents one of the objectives of the project EuLakes (European Lakes Under Environmental Stressors, Supporting lake governance to mitigate the impact of climate change, Reg. N. 2CE243P3), launched in 2010 within the Central European Inititiative. The project consortium comprises lakes of different morphology and prevalent human uses, including the meso-eutrophic Lake Neusiedl, the largest Austrian lake (total area 315 km2), and the westernmost shallow (mean depth 1.2 m) steppe lake of the Euro-Asiatic continent. The volume of Lake Neusiedl can potentially change over the years, in relation with changing balance between atmospheric precipitation and lake water evapotranspiration. Changing water budget, together with high lake salinity and turbidity, have important implications over the lake ecosystem. This contribution illustrates results of the multi-proxi palaeolimnological reconstruction of ecologial changes occurred in Lake Neusiedl during the last ca. 140 years, i.e. since the end of the last "vanished-lake" stage (1865-1871). Geochemical and biological proxies anticipate the increase in lake productivity of ca. 10 years (1950s) respect to what reported in the literature. Diatom species composition indicate a biological lake recovery in the late 1980s, and suggest a second increment in lake productivity since the late 1990s, possibly in relation with the progressive increase in the nitrogen input from agriculture. Abundance of diatoms typical of brackish waters indicated no significant long-term change in lake salinity, while variations in species toleranting dessiccation confirm the vulnerability of Lake Neusiedl toward climate-driven changes in the lake water balance. This fragility is aggravated by the the semi-arid climate conditions of the catchemnt

  20. Self-organized Ce(1-x)Gd(x)O(2-y) nanowire networks with very fast coarsening driven by attractive elastic interactions.

    Science.gov (United States)

    Gibert, Marta; Abellán, Patricia; Benedetti, Alessandro; Puig, Teresa; Sandiumenge, Felip; García, Alberto; Obradors, Xavier

    2010-12-06

    Assembling arrays of ordered nanowires is a key objective for many of their potential applications. However, a lack of understanding and control of the nanowires' growth mechanisms limits their thorough development. In this work, an appealing new path towards self-organized epitaxial nanowire networks produced by high-throughput solution methods is reported. Two requisites are identified to generate the nanowires: a thermodynamic driving force for an unrestricted elongated equilibrium island shape, and a very fast effective coarsening rate. These requirements are met in anisotropically strained Ce(1-x)Gd(x)O(2-y) nanowires with the (011) orientation grown on the (001) surface of LaAlO(3) substrates. Nanowires with aspect ratios above ≈100 oriented along two mutually orthogonal axes are obtained leading to labyrinthine networks. A very fast effective nanowire growth rate (≈60 nm min(-1)) for ex-situ thermally annealed nanostructures derives from simultaneous kinetic processes occurring in a branched network. Ostwald ripening and anisotropic dynamic coalescence, both promoted by strain-driven attractive nanowire interaction, and rapid recrystallization, enabled by fast atomic diffusion associated with a high concentration of oxygen vacancies, contribute to such an effective growth rate. This bottom-up approach to self-organized nanowire growth has a wide potential for many materials and functionalities.

  1. Vitamin D Receptor Activator Use and Cause-specific Death among dialysis Patients: a Nationwide Cohort Study using Coarsened Exact Matching

    Science.gov (United States)

    Obi, Yoshitsugu; Hamano, Takayuki; Wada, Atsushi; Tsubakihara, Yoshiharu; Nakai, Shigeru; Hanafusa, Norio; Masakane, Ikuto; Itami, Noritomo; Yamagata, Kunihiro; Shinoda, Toshio; Kazama, Junichiro James; Watanabe, Yuzo; Shigematsu, Takashi; Marubayashi, Seiji; Morita, Osamu; Kimata, Naoki; Wakai, Kenji; Ogata, Satoshi; Iseki, Kunitoshi; Yamamoto, Keiichi; Shintani, Ayumu

    2017-01-01

    Vitamin D receptor activators (VDRA) may exert pleiotropic effects on cardiovascular disease, malignancy, and infections among dialysis patients, but recent studies have mainly focused on cardiovascular outcomes. Among 8,675 patients who started dialysis in 2007 and who survived until January 1, 2010, listed in the Renal Data Registry of the Japanese Society for Dialysis Therapy, 5,365 VDRA users were matched to 3,203 non-users based on clinically relevant variables at the end of 2009 using the coarsened exact matching procedure. Until December 31, 2011, a total of 1,128 deaths occurred, of which 468 (42%) were cardiovascular deaths, 229 (20%) were infection-related deaths, and 141 (12%) were malignancy-related deaths. Multivariable survival analyses accounting for intra-region correlation revealed that VDRA use was significantly associated with lower rates of infection- and malignancy-related deaths [subhazard ratio 0.62 (95% CI, 0.52–0.73) and 0.70 (95% CI, 0.50–0.97), respectively] but not with cardiovascular death [subhazard ratio 0.86 (95% CI, 0.72–1.04)]. Future randomized clinical trials with a sufficient sample size and an adequate follow-up period are warranted to test the clinical effectiveness of VDRA on infection and malignancy, rather than cardiovascular disease, among dialysis patients. PMID:28139665

  2. Charged anisotropic matter with linear or nonlinear equation of state

    CERN Document Server

    Varela, Victor; Ray, Saibal; Chakraborty, Kaushik; Kalam, Mehedi

    2010-01-01

    Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplification achieved with the introduction of electric charge were noticed as well. We deal with self-gravitating, charged, anisotropic fluids and get even more flexibility in solving the Einstein-Maxwell equations. In order to discuss analytical solutions we extend Krori and Barua's method to include pressure anisotropy and linear or non-linear equations of state. The field equations are reduced to a system of three algebraic equations for the anisotropic pressures as well as matter and electrostatic energy densities. Attention is paid to compact sources characterized by positive matter density and positive radial pressure. Arising solutions satisfy the energy conditions of general relativity. Spheres with vanishing net charge contain fluid elements with unbounded proper charge density located at the fluid-vacuum interface. Notably the...

  3. Nonlinear effects of dark energy clustering beyond the acoustic scales

    Energy Technology Data Exchange (ETDEWEB)

    Anselmi, Stefano [Department of Physics/CERCA/ISO, Case Western Reserve University, Cleveland, OH 44106-7079 (United States); Nacir, Diana López [The Abdus Salam International Center for Theoretical Physics, Strada costiera 11, I-34151 Trieste (Italy); Sefusatti, Emiliano, E-mail: stefano.anselmi@case.edu, E-mail: dlopez_n@ictp.it, E-mail: emiliano.sefusatti@brera.inaf.it [INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Saint Lucia) (Italy)

    2014-07-01

    We extend the resummation method of Anselmi and Pietroni (2012) to compute the total density power spectrum in models of quintessence characterized by a vanishing speed of sound. For standard ΛCDM cosmologies, this resummation scheme allows predictions with an accuracy at the few percent level beyond the range of scales where acoustic oscillations are present, therefore comparable to other, common numerical tools. In addition, our theoretical approach indicates an approximate but valuable and simple relation between the power spectra for standard quintessence models and models where scalar field perturbations appear at all scales. This, in turn, provides an educated guess for the prediction of nonlinear growth in models with generic speed of sound, particularly valuable since no numerical results are yet available.

  4. Modified Semi-Classical Methods for Nonlinear Quantum Oscillations Problems

    CERN Document Server

    Moncrief, Vincent; Maitra, Rachel

    2012-01-01

    We develop a modified semi-classical approach to the approximate solution of Schrodinger's equation for certain nonlinear quantum oscillations problems. At lowest order, the Hamilton-Jacobi equation of the conventional semi-classical formalism is replaced by an inverted-potential-vanishing-energy variant thereof. Under smoothness, convexity and coercivity hypotheses on its potential energy function, we prove, using the calculus of variations together with the Banach space implicit function theorem, the existence of a global, smooth `fundamental solution'. Higher order quantum corrections, for ground and excited states, are computed through the integration of associated systems of linear transport equations, and formal expansions for the corresponding energy eigenvalues obtained by imposing smoothness on the quantum corrections to the eigenfunctions. For linear oscillators our expansions naturally truncate, reproducing the well-known solutions for the energy eigenfunctions and eigenvalues. As an application, w...

  5. Improved Methodology for Parameter Inference in Nonlinear, Hydrologic Regression Models

    Science.gov (United States)

    Bates, Bryson C.

    1992-01-01

    A new method is developed for the construction of reliable marginal confidence intervals and joint confidence regions for the parameters of nonlinear, hydrologic regression models. A parameter power transformation is combined with measures of the asymptotic bias and asymptotic skewness of maximum likelihood estimators to determine the transformation constants which cause the bias or skewness to vanish. These optimized constants are used to construct confidence intervals and regions for the transformed model parameters using linear regression theory. The resulting confidence intervals and regions can be easily mapped into the original parameter space to give close approximations to likelihood method confidence intervals and regions for the model parameters. Unlike many other approaches to parameter transformation, the procedure does not use a grid search to find the optimal transformation constants. An example involving the fitting of the Michaelis-Menten model to velocity-discharge data from an Australian gauging station is used to illustrate the usefulness of the methodology.

  6. Non-linear Oscillations of Compact Stars and Gravitational Waves

    CERN Document Server

    Passamonti, A

    2006-01-01

    This thesis investigates in the time domain a particular class of second order perturbations of a perfect fluid non-rotating compact star: those arising from the coupling between first order radial and non-radial perturbations. This problem has been treated by developing a gauge invariant formalism based on the 2-parameter perturbation theory (Sopuerta, Bruni and Gualtieri, 2004) where the radial and non-radial perturbations have been separately parameterized. The non-linear perturbations obey inhomogeneous partial differential equations, where the structure of the differential operator is given by the previous perturbative orders and the source terms are quadratic in the first order perturbations. In the exterior spacetime the sources vanish, thus the gravitational wave properties are completely described by the second order Zerilli and Regge-Wheeler functions. As main initial configuration we have considered a first order differentially rotating and radially pulsating star. Although at first perturbative or...

  7. The de Sitter limit of inflation and non-linear perturbation theory

    DEFF Research Database (Denmark)

    Jarnhus, Philip; Sloth, Martin Snoager

    2008-01-01

    We study the fourth order action of the comoving curvature perturbation in an inflationary universe in order to understand more systematically the de Sitter limit in nonlinear cosmological perturbation theory. We derive the action of the curvature perturbation to fourth order in the comoving gaug......, and show that it vanishes sufficiently fast in the de Sitter limit. By studying the de Sitter limit, we then extrapolate to the n'th order action of the comoving curvature perturbation and discuss the slow-roll order of the n-point correlation function....

  8. The de Sitter limit of inflation and non-linear perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Jarnhus, Philip R; Sloth, Martin S, E-mail: pjarn@phys.au.dk, E-mail: sloth@phys.au.dk [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark)

    2008-02-15

    We study the fourth-order action of the comoving curvature perturbation in an inflationary universe in order to understand more systematically the de Sitter limit in non-linear cosmological perturbation theory. We derive the action of the curvature perturbation to fourth order in the comoving gauge, and show that it vanishes sufficiently fast in the de Sitter limit. By studying the de Sitter limit, we then extrapolate to the nth-order action of the comoving curvature perturbation and discuss the slow-roll order of the n-point correlation function.

  9. Lasers for nonlinear microscopy.

    Science.gov (United States)

    Wise, Frank

    2013-03-01

    Various versions of nonlinear microscopy are revolutionizing the life sciences, almost all of which are made possible because of the development of ultrafast lasers. In this article, the main properties and technical features of short-pulse lasers used in nonlinear microscopy are summarized. Recent research results on fiber lasers that will impact future instruments are also discussed.

  10. Nonlinear optical materials.

    Science.gov (United States)

    Eaton, D F

    1991-07-19

    The current state of materials development in nonlinear optics is summarized, and the promise of these materials is critically evaluated. Properties and important materials constants of current commercial materials and of new, promising, inorganic and organic molecular and polymeric materials with potential in second- and third-order nonlinear optical applications are presented.

  11. Estimating nonlinear models

    Science.gov (United States)

    Billings, S. A.

    1988-03-01

    Time and frequency domain identification methods for nonlinear systems are reviewed. Parametric methods, prediction error methods, structure detection, model validation, and experiment design are discussed. Identification of a liquid level system, a heat exchanger, and a turbocharge automotive diesel engine are illustrated. Rational models are introduced. Spectral analysis for nonlinear systems is treated. Recursive estimation is mentioned.

  12. Nonlinear Cross Gramians

    NARCIS (Netherlands)

    Ionescu, T. C.; Scherpen, J. M. A.; Korytowski, A; Malanowski, K; Mitkowski, W; Szymkat, M

    2009-01-01

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain

  13. Engineered nonlinear lattices

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Christiansen, Peter Leth; Torner, L.

    1999-01-01

    We show that with the quasi-phase-matching technique it is possible to fabricate stripes of nonlinearity that trap and guide light like waveguides. We investigate an array of such stripes and find that when the stripes are sufficiently narrow, the beam dynamics is governed by a quadratic nonlinear...

  14. Controllability in nonlinear systems

    Science.gov (United States)

    Hirschorn, R. M.

    1975-01-01

    An explicit expression for the reachable set is obtained for a class of nonlinear systems. This class is described by a chain condition on the Lie algebra of vector fields associated with each nonlinear system. These ideas are used to obtain a generalization of a controllability result for linear systems in the case where multiplicative controls are present.

  15. Nonlinear Maneuver Autopilot

    Science.gov (United States)

    Menon, P. K. A.; Badgett, M. E.; Walker, R. A.

    1992-01-01

    Trajectory-control laws based on singular-perturbation theory and nonlinear dynamical modeling. Nonlinear maneuver autopilot commands flight-test trajectories of F-15 airplane. Underlying theory of controller enables separation of variables processed in fast and slow control loops, reducing amount of computation required.

  16. An elementary proof of the vanishing of the second cohomology of the Witt and Virasoro algebra with values in the adjoint module

    CERN Document Server

    Schlichenmaier, Martin

    2011-01-01

    By elementary and direct calculations the vanishing of the (algebraic) second Lie algebra cohomology of the Witt and the Virasoro algebra with values in the adjoint module is shown. This yields infinitesimal and formal rigidity or these algebras. The first (and up to now only) proof of this important result was given 1989 by Fialowski in an unpublished note. It is based on cumbersome calculations. Compared to the original proof the presented one is quite elegant and considerably simpler.

  17. Nonlinear optics and photonics

    CERN Document Server

    He, Guang S

    2015-01-01

    This book provides a comprehensive presentation on most of the major topics in nonlinear optics and photonics, with equal emphasis on principles, experiments, techniques, and applications. It covers many major new topics including optical solitons, multi-photon effects, nonlinear photoelectric effects, fast and slow light , and Terahertz photonics. Chapters 1-10 present the fundamentals of modern nonlinear optics, and could be used as a textbook with problems provided at the end of each chapter. Chapters 11-17 cover the more advanced topics of techniques and applications of nonlinear optics and photonics, serving as a highly informative reference for researchers and experts working in related areas. There are also 16 pages of color photographs to illustrate the visual appearances of some typical nonlinear optical effects and phenomena. The book could be adopted as a textbook for both undergraduates and graduate students, and serve as a useful reference work for researchers and experts in the fields of physics...

  18. Nonlinear optical systems

    CERN Document Server

    Lugiato, Luigi; Brambilla, Massimo

    2015-01-01

    Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.

  19. Nonlinear flap-lag-extensional vibrations of rotating, pretwisted, preconed beams including Coriolis effects

    Science.gov (United States)

    Subrahmanyam, K. B.; Kaza, K. R. V.

    1985-01-01

    The effects of pretwist, precone, setting angle, Coriolis forces and second degree geometric nonlinearities on the natural frequencies, steady state deflections and mode shapes of rotating, torsionally rigid, cantilevered beams were studied. The governing coupled equations of flap lag extensional motion are derived including the effects of large precone and retaining geometric nonlinearities up to second degree. The Galerkin method, with nonrotating normal modes, is used for the solution of both steady state nonlinear equations and linear perturbation equations. Parametric indicating the individual and collective effects of pretwist, precone, Coriolis forces and second degree geometric nonlinearities on the steady state deflection, natural frequencies and mode shapes of rotating blades are presented. It is indicated that the second degree geometric nonlinear terms, which vanish for zero precone, can produce frequency changes of engineering significance. Further confirmation of the validity of including those generated by MSC NASTRAN. It is indicated that the linear and nonlinear Coriolis effects must be included in analyzing thick blades. The Coriolis effects are significant on the first flatwise and the first edgewise modes.

  20. Nonlinear cochlear mechanics.

    Science.gov (United States)

    Zweig, George

    2016-05-01

    An earlier paper characterizing the linear mechanical response of the organ of Corti [J. Acoust. Soc. Am. 138, 1102-1121 (2015)] is extended to the nonlinear domain. Assuming the existence of nonlinear oscillators nonlocally coupled through the pressure they help create, the oscillator equations are derived and examined when the stimuli are modulated tones and clicks. The nonlinearities are constrained by the requirements of oscillator stability and the invariance of zero crossings in the click response to changes in click amplitude. The nonlinear oscillator equations for tones are solved in terms of the fluid pressure that drives them, and its time derivative, presumably a proxy for forces created by outer hair cells. The pressure equation is reduced to quadrature, the integrand depending on the oscillators' responses. The resulting nonlocally coupled nonlinear equations for the pressure, and oscillator amplitudes and phases, are solved numerically in terms of the fluid pressure at the stapes. Methods for determining the nonlinear damping directly from measurements are described. Once the oscillators have been characterized from their tone and click responses, the mechanical response of the cochlea to natural sounds may be computed numerically. Signal processing inspired by cochlear mechanics opens up a new area of nonlocal nonlinear time-frequency analysis.

  1. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind P

    2001-01-01

    The Optical Society of America (OSA) and SPIE - The International Society for Optical Engineering have awarded Govind Agrawal with an honorable mention for the Joseph W. Goodman Book Writing Award for his work on Nonlinear Fiber Optics, 3rd edition.Nonlinear Fiber Optics, 3rd Edition, provides a comprehensive and up-to-date account of the nonlinear phenomena occurring inside optical fibers. It retains most of the material that appeared in the first edition, with the exception of Chapter 6, which is now devoted to the polarization effects relevant for light propagation in optical

  2. Will Nonlinear Backcalculation Help?

    DEFF Research Database (Denmark)

    Ullidtz, Per

    2000-01-01

    demonstrates, that treating the subgrade as a nonlinear elastic material, can result in more realistic moduli and a much better agreement between measured and calculated stresses and strains.The response of nonlinear elastic materials can be calculated using the Finite Element Method (FEM). A much simpler...... approach is to use the Method of Equivalent Thicknesses (MET), modified for a nonlinear subgrade. The paper includes an example where moduli backcalculated using FEM, linear elastic theory and MET are compared. Stresses and strains predicted by the three methods are also compared to measured values...

  3. Nonlinear graphene metamaterial

    CERN Document Server

    Nikolaenko, Andrey E; Atmatzakis, Evangelos; Luo, Zhiqiang; Shen, Ze Xiang; De Angelis, Francesco; Boden, Stuart A; Di Fabrizio, Enzo; Zheludev, Nikolay I

    2012-01-01

    We demonstrate that the broadband nonlinear optical response of graphene can be resonantly enhanced by more than an order of magnitude through hybridization with a plasmonic metamaterial,while retaining an ultrafast nonlinear response time of ~1 ps. Transmission modulation close to ~1% is seen at a pump uence of ~0.03 mJ/cm^2 at the wavelength of ~1600 nm. This approach allows to engineer and enhance graphene's nonlinearity within a broad wavelength range enabling applications in optical switching, mode-locking and pulse shaping.

  4. Coarsening kinetics, thermodynamic properties, and interfacial characteristics of δ' precipitates in Al-Li alloys taking into account the Gibbs-Thomson effect

    Science.gov (United States)

    Tsao, C.-S.; Chen, C.-Y.; Huang, J.-Y.

    2004-11-01

    The structure factor model of small-angle x-ray scattering (SAXS) analysis is validated herein by transmission electron microscopy (TEM) result regarding the volume fraction and size of δ' precipitates. The kinetic behaviors of the number density and volume fraction of δ' precipitates in Al-Li alloys during the coarsening stage are quantitatively investigated by SAXS. The results indicate that the conventional kinetic law must be replaced by a more general equation that incorporates the Gibbs-Thomson effect and the time-dependence of the volume fraction during Ostwald ripening. This work also proposes new methods that combine the Gibbs-Thomson effect and the traditional SAXS equation to resolve more reliably and model independently the interfacial energy, the concentration of solute Li in the α matrix in equilibrium with δ' particles of a nanoscale radius Cαr , the equilibrium solubility of the α phase Ceα and the equilibrium concentration of δ' particles. The Gibbs-Thomson effect considers the effects of the interfacial energy and particle size on the equilibrium concentration. This effect quantitatively clarifies that the Cαr value is size-dependent and is related to the Ceα value and the interfacial energy. The traditional SAXS equation determines the Li concentrations in the δ' particles and the matrix from the measured scattering contrast. The traditionally determined solubility is in fact the Cαr value and is mistakenly regarded as the equilibrium concentration Ceα (corresponding to the radius is infinite). These results are compared to other results obtained by SAXS, TEM, and calculation. The time evolution of the transition interfacial layers between δ' particles and the matrix is extensively investigated using SAXS.

  5. Multipolar nonlinear nanophotonics

    CERN Document Server

    Smirnova, Daria

    2016-01-01

    Nonlinear nanophotonics is a rapidly developing field with many useful applications for a design of nonlinear nanoantennas, light sources, nanolasers, sensors, and ultrafast miniature metadevices. A tight confinement of the local electromagnetic fields in resonant photonic nanostructures can boost nonlinear optical effects, thus offering versatile opportunities for subwavelength control of light. To achieve the desired functionalities, it is essential to gain flexible control over the near- and far-field properties of nanostructures. Thus, both modal and multipolar analyses are widely exploited for engineering nonlinear scattering from resonant nanoscale elements, in particular for enhancing the near-field interaction, tailoring the far-field multipolar interference, and optimization of the radiation directionality. Here, we review the recent advances in this recently emerged research field ranging from metallic structures exhibiting localized plasmonic resonances to hybrid metal-dielectric and all-dielectric...

  6. Solitons in nonlinear lattices

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2010-01-01

    This article offers a comprehensive survey of results obtained for solitons and complex nonlinear wave patterns supported by purely nonlinear lattices (NLs), which represent a spatially periodic modulation of the local strength and sign of the nonlinearity, and their combinations with linear lattices. A majority of the results obtained, thus far, in this field and reviewed in this article are theoretical. Nevertheless, relevant experimental settings are surveyed too, with emphasis on perspectives for implementation of the theoretical predictions in the experiment. Physical systems discussed in the review belong to the realms of nonlinear optics (including artificial optical media, such as photonic crystals, and plasmonics) and Bose-Einstein condensation (BEC). The solitons are considered in one, two, and three dimensions (1D, 2D, and 3D). Basic properties of the solitons presented in the review are their existence, stability, and mobility. Although the field is still far from completion, general conclusions c...

  7. Nonlinear plasmonic antennas

    Directory of Open Access Journals (Sweden)

    Shakeeb Bin Hasan

    2014-12-01

    Full Text Available Contrary to traditional optical elements, plasmonic antennas made from nanostructured metals permit the localization of electromagnetic fields on length scales much smaller than the wavelength of light. This results in huge amplitudes for the electromagnetic field close to the antenna being conducive for the observation of nonlinear effects already at moderate pump powers. Thus, these antennas exhibit a promising potential to achieve optical frequency conversion and all-optical control of light at the nano-scale. This opens unprecedented opportunities for ultrafast nonlinear spectroscopy, sensing devices, on-chip optical frequency conversion, nonlinear optical metamaterials, and novel photon sources. Here, we review some of the recent advances in exploiting the potential of plasmonic antennas to realize robust nonlinear applications.

  8. Ultrafast nonlinear optics

    CERN Document Server

    Leburn, Christopher; Reid, Derryck

    2013-01-01

    The field of ultrafast nonlinear optics is broad and multidisciplinary, and encompasses areas concerned with both the generation and measurement of ultrashort pulses of light, as well as those concerned with the applications of such pulses. Ultrashort pulses are extreme events – both in terms of their durations, and also the high peak powers which their short durations can facilitate. These extreme properties make them powerful experiment tools. On one hand, their ultrashort durations facilitate the probing and manipulation of matter on incredibly short timescales. On the other, their ultrashort durations can facilitate high peak powers which can drive highly nonlinear light-matter interaction processes. Ultrafast Nonlinear Optics covers a complete range of topics, both applied and fundamental in nature, within the area of ultrafast nonlinear optics. Chapters 1 to 4 are concerned with the generation and measurement of ultrashort pulses. Chapters 5 to 7 are concerned with fundamental applications of ultrasho...

  9. Nonlinear Source Emulator

    DEFF Research Database (Denmark)

    Nguyen-Duy, Khiem

    and remains the prime source of energy in non-terrestrial applications such as those in sky-explorers. However, a renewable energy source is expensive, bulky, and its performance is weather dependent, which make testing of downstream converters very difficult. As a result, a nonlinear source emulator (NSE......) is a good solution to solve the problems associated with the use of real nonlinear sources in testing phases. However, a recent technical survey conducted during this work shows that most existing NSEs have only been concerned with simulating nonlinear systems in terrestrial applications. Furthermore......, their dynamic performance were not fast enough in order to imitate how a real nonlinear energy source would react under extreme conditions and operation modes. Particularly, a system in the sky can experience a step change of sunlight irradiation. Moreover, operation modes may include load step between nominal...

  10. Introduction to nonlinear science

    CERN Document Server

    Nicolis, G

    1995-01-01

    One of the most unexpected results in science in recent years is that quite ordinary systems obeying simple laws can give rise to complex, nonlinear or chaotic, behavior. In this book, the author presents a unified treatment of the concepts and tools needed to analyze nonlinear phenomena and to outline some representative applications drawn from the physical, engineering, and biological sciences. Some of the interesting topics covered include: dynamical systems with a finite number of degrees of freedom, linear stability analysis of fixed points, nonlinear behavior of fixed points, bifurcation analysis, spatially distributed systems, broken symmetries, pattern formation, and chaotic dynamics. The author makes a special effort to provide a logical connection between ordinary dynamical systems and spatially extended systems, and to balance the emphasis on chaotic behavior and more classical nonlinear behavior. He also develops a statistical approach to complex systems and compares it to traditional deterministi...

  11. Nonlinear magnetoinductive transmission lines

    CERN Document Server

    Lazarides, Nikos; Tsironis, G P

    2011-01-01

    Power transmission in one-dimensional nonlinear magnetic metamaterials driven at one end is investigated numerically and analytically in a wide frequency range. The nonlinear magnetic metamaterials are composed of varactor-loaded split-ring resonators which are coupled magnetically through their mutual inductances, forming thus a magnetoiductive transmission line. In the linear limit, significant power transmission along the array only appears for frequencies inside the linear magnetoinductive wave band. We present analytical, closed form solutions for the magnetoinductive waves transmitting the power in this regime, and their discrete frequency dispersion. When nonlinearity is important, more frequency bands with significant power transmission along the array may appear. In the equivalent circuit picture, the nonlinear magnetoiductive transmission line driven at one end by a relatively weak electromotive force, can be modeled by coupled resistive-inductive-capacitive (RLC) circuits with voltage-dependent cap...

  12. Optimization under Nonlinear Constraints

    OpenAIRE

    1982-01-01

    In this paper a timesaving method is proposed for maximizing likelihood functions when the parameter space is subject to nonlinear constraints, expressible as second order polynomials. The suggested approach is especially attractive when dealing with systems with many parameters.

  13. Nonlinearity in nanomechanical cantilevers

    DEFF Research Database (Denmark)

    Villanueva Torrijo, Luis Guillermo; Karabalin, R. B.; Matheny, M. H.

    2013-01-01

    Euler-Bernoulli beam theory is widely used to successfully predict the linear dynamics of micro-and nanocantilever beams. However, its capacity to characterize the nonlinear dynamics of these devices has not yet been rigorously assessed, despite its use in nanoelectromechanical systems development....... These findings underscore the delicate balance between inertial and geometric nonlinear effects in the fundamental mode, and strongly motivate further work to develop theories beyond the Euler-Bernoulli approximation. DOI: 10.1103/PhysRevB.87.024304....... In this article, we report the first highly controlled measurements of the nonlinear response of nanomechanical cantilevers using an ultralinear detection system. This is performed for an extensive range of devices to probe the validity of Euler-Bernoulli theory in the nonlinear regime. We find that its...

  14. Nonlinear Stokes Mueller Polarimetry

    CERN Document Server

    Samim, Masood; Barzda, Virginijus

    2015-01-01

    The Stokes Mueller polarimetry is generalized to include nonlinear optical processes such as second- and third-harmonic generation, sum- and difference-frequency generations. The overall algebraic form of the polarimetry is preserved, where the incoming and outgoing radiations are represented by column vectors and the intervening medium is represented by a matrix. Expressions for the generalized nonlinear Stokes vector and the Mueller matrix are provided in terms of coherency and correlation matrices, expanded by higher-dimensional analogues of Pauli matrices. In all cases, the outgoing radiation is represented by the conventional $4\\times 1$ Stokes vector, while dimensions of the incoming radiation Stokes vector and Mueller matrix depend on the order of the process being examined. In addition, relation between nonlinear susceptibilities and the measured Mueller matrices are explicitly provided. Finally, the approach of combining linear and nonlinear optical elements is discussed within the context of polarim...

  15. Adaptive and Nonlinear Control

    Science.gov (United States)

    1992-02-29

    in [22], we also applied the concept of zero dynamics to the problem of exact linearization of a nonlinear control system by dynamic feedback. Exact ...nonlinear systems, although it was well-known that the conditions for exact linearization are very stringent and consequently do not apply to a broad...29th IEEE Conference n Decision and Control, Invited Paper delivered by Dr. Gilliam. Exact Linearization of Zero Dynamics, 29th IEEE Conference on

  16. Nonlinear Optics and Turbulence

    Science.gov (United States)

    1992-10-01

    currently at Queen Mary College, London Patrick Dunne, (Ph.D., 1987, M.I.T., Hydrodynamic Stability, Nonlinear Waves), 1987-1988. Alecsander Dyachenko...U I I I U I I 3 9 3 V. BIOGRAPHIES A. FACULTY BRUCE BAYLY, 31, Ph.D. 1986, Princeton University. Postdoctoral visiting member 1986-88 at Courant...Caputo, A. C. Newell, and M. Shelley , "Nonlinear Wave Propagation Through a Random Medium and Soliton Tunneling", Integrable Systems and

  17. CONNECTING THE VANISHING FLORA, FAUNA AND ITS RELATION TO THE INDIAN REMOVAL POLICY AS SEEN IN COOPERS THE LEATHERSTOCKING TALES

    Directory of Open Access Journals (Sweden)

    Ceisy Nita Wuntu

    2016-02-01

    Full Text Available This study aims at connecting the vanishing flora, fauna and its Relation to the Indian removal policy in Coopers The Leatherstocking Tales. This research applies an American Studies interdisciplinary principle supplemented by the myth and symbol theory proposed by Henry Nash Smith. Smith claimed the importance of imaginative works in revealing American culture. He declared that the historical, anthropological and cultural, sociological, and ecological data as covered in this research can be equipped by data from imaginative works. Hence, in this research, those data are presented integratedly in their context of past and present. In this research, in order to highlight environmental matters in Coopers The Leatherstocking Tales, the analysis covers the data above that are integrated with the data revealed in The Leatherstocking Tales as a whole by employing the concept of ecocriticism. The spirit of the immigrants to have a better life in the new world, stimulated by its rich, lush and beautiful circumstances, in fact, is not an aim of a sustainable life. The desire to improve their life is not enough without using and treating its environment wisely as well as facing it with the environmental conservation paradigm. The spirit of doing the exploitation is a consequence of western humanism value. The reason of coming to America to avoid the population density as well as the competition of life cannot be attained when the immigrants experience the same population density and harsh competition as in their old world and when the beautiful nature disappears, the forests become cities, the tranquility becomes noisy and crowded, and the people experience the uncomfortable life that many kinds of conflict can follow. It is not on the right path when they cannot maintain the grandeur of nature, because they are not directing their way to the right, sustainable way of life as alerted and meant by Cooper. Ecologically, the superabundance of the land when

  18. Robust Nonlinear Neural Codes

    Science.gov (United States)

    Yang, Qianli; Pitkow, Xaq

    2015-03-01

    Most interesting natural sensory stimuli are encoded in the brain in a form that can only be decoded nonlinearly. But despite being a core function of the brain, nonlinear population codes are rarely studied and poorly understood. Interestingly, the few existing models of nonlinear codes are inconsistent with known architectural features of the brain. In particular, these codes have information content that scales with the size of the cortical population, even if that violates the data processing inequality by exceeding the amount of information entering the sensory system. Here we provide a valid theory of nonlinear population codes by generalizing recent work on information-limiting correlations in linear population codes. Although these generalized, nonlinear information-limiting correlations bound the performance of any decoder, they also make decoding more robust to suboptimal computation, allowing many suboptimal decoders to achieve nearly the same efficiency as an optimal decoder. Although these correlations are extremely difficult to measure directly, particularly for nonlinear codes, we provide a simple, practical test by which one can use choice-related activity in small populations of neurons to determine whether decoding is suboptimal or optimal and limited by correlated noise. We conclude by describing an example computation in the vestibular system where this theory applies. QY and XP was supported by a grant from the McNair foundation.

  19. Nonlinear Multiantenna Detection Methods

    Directory of Open Access Journals (Sweden)

    Chen Sheng

    2004-01-01

    Full Text Available A nonlinear detection technique designed for multiple-antenna assisted receivers employed in space-division multiple-access systems is investigated. We derive the optimal solution of the nonlinear spatial-processing assisted receiver for binary phase shift keying signalling, which we refer to as the Bayesian detector. It is shown that this optimal Bayesian receiver significantly outperforms the standard linear beamforming assisted receiver in terms of a reduced bit error rate, at the expense of an increased complexity, while the achievable system capacity is substantially enhanced with the advent of employing nonlinear detection. Specifically, when the spatial separation expressed in terms of the angle of arrival between the desired and interfering signals is below a certain threshold, a linear beamformer would fail to separate them, while a nonlinear detection assisted receiver is still capable of performing adequately. The adaptive implementation of the optimal Bayesian detector can be realized using a radial basis function network. Two techniques are presented for constructing block-data-based adaptive nonlinear multiple-antenna assisted receivers. One of them is based on the relevance vector machine invoked for classification, while the other on the orthogonal forward selection procedure combined with the Fisher ratio class-separability measure. A recursive sample-by-sample adaptation procedure is also proposed for training nonlinear detectors based on an amalgam of enhanced -means clustering techniques and the recursive least squares algorithm.

  20. Nonlinear systems in medicine.

    Science.gov (United States)

    Higgins, John P

    2002-01-01

    Many achievements in medicine have come from applying linear theory to problems. Most current methods of data analysis use linear models, which are based on proportionality between two variables and/or relationships described by linear differential equations. However, nonlinear behavior commonly occurs within human systems due to their complex dynamic nature; this cannot be described adequately by linear models. Nonlinear thinking has grown among physiologists and physicians over the past century, and non-linear system theories are beginning to be applied to assist in interpreting, explaining, and predicting biological phenomena. Chaos theory describes elements manifesting behavior that is extremely sensitive to initial conditions, does not repeat itself and yet is deterministic. Complexity theory goes one step beyond chaos and is attempting to explain complex behavior that emerges within dynamic nonlinear systems. Nonlinear modeling still has not been able to explain all of the complexity present in human systems, and further models still need to be refined and developed. However, nonlinear modeling is helping to explain some system behaviors that linear systems cannot and thus will augment our understanding of the nature of complex dynamic systems within the human body in health and in disease states.

  1. Handbook of nonlinear optical crystals

    CERN Document Server

    Dmitriev, Valentin G; Nikogosyan, David N

    1991-01-01

    This Handbook of Nonlinear Optical Crystals provides a complete description of the properties and applications of nonlinear crystals In addition, it presents the most important equations for calculating the main parameters of nonlinear frequency converters This comprehensive reference work will be of great value to all scientists and engineers working in nonlinear optics, quantum electronics and laser physics

  2. Solitons and Vortices in Two-dimensional Discrete Nonlinear Schrodinger Systems with Spatially Modulated Nonlinearity

    CERN Document Server

    Kevrekidis, P G; Saxena, A; Frantzeskakis, D J; Bishop, A R

    2014-01-01

    We consider a two-dimensional (2D) generalization of a recently proposed model [Phys. Rev. E 88, 032905 (2013)], which gives rise to bright discrete solitons supported by the defocusing nonlinearity whose local strength grows from the center to the periphery. We explore the 2D model starting from the anti-continuum (AC) limit of vanishing coupling. In this limit, we can construct a wide variety of solutions including not only single-site excitations, but also dipole and quadrupole ones. Additionally, two separate families of solutions are explored: the usual "extended" unstaggered bright solitons, in which all sites are excited in the AC limit, with the same sign across the lattice (they represent the most robust states supported by the lattice, their 1D counterparts being what was considered as 1D bright solitons in the above-mentioned work), and the vortex cross, which is specific to the 2D setting. For all the existing states, we explore their stability (analytically, whenever possible). Typical scenarios ...

  3. Nonlinear Approaches in Engineering Applications

    CERN Document Server

    Jazar, Reza

    2012-01-01

    Nonlinear Approaches in Engineering Applications focuses on nonlinear phenomena that are common in the engineering field. The nonlinear approaches described in this book provide a sound theoretical base and practical tools to design and analyze engineering systems with high efficiency and accuracy and with less energy and downtime. Presented here are nonlinear approaches in areas such as dynamic systems, optimal control and approaches in nonlinear dynamics and acoustics. Coverage encompasses a wide range of applications and fields including mathematical modeling and nonlinear behavior as applied to microresonators, nanotechnologies, nonlinear behavior in soil erosion,nonlinear population dynamics, and optimization in reducing vibration and noise as well as vibration in triple-walled carbon nanotubes. This book also: Provides a complete introduction to nonlinear behavior of systems and the advantages of nonlinearity as a tool for solving engineering problems Includes applications and examples drawn from the el...

  4. Theory of nonlinear harmonic generation in free-electron lasers with helical wigglers

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M.

    2007-05-15

    CoherentHarmonicGeneration (CHG), and in particularNonlinearHarmonicGeneration (NHG), is of importance for both short wavelength Free-Electron Lasers (FELs), in relation with the achievement of shorter wavelengths with a fixed electron-beam energy, and high-average power FEL resonators, in relation with destructive effects of higher harmonics radiation on mirrors. In this paper we present a treatment of NHG from helical wigglers with particular emphasis on the second harmonic. Our study is based on an exact analytical solution of Maxwell's equations, derived with the help of a Green's function method. In particular, we demonstrate that nonlinear harmonic generation (NHG) fromhelicalwigglers vanishes on axis. Our conclusion is in open contrast with results in literature, that include a kinematical mistake in the description of the electron motion. (orig.)

  5. Cosmological perturbations of self-accelerating universe in nonlinear massive gravity

    CERN Document Server

    Gumrukcuoglu, A Emir; Mukohyama, Shinji

    2011-01-01

    We study cosmological perturbations of self-accelerating universe solutions in the recently proposed nonlinear theory of massive gravity, with general matter content. While the broken diffeomorphism invariance implies that there generically are 2 tensor, 2 vector and 2 scalar degrees of freedom in the gravity sector, we find that the scalar and vector degrees have vanishing kinetic terms and nonzero mass terms. Depending on their nonlinear behavior, this indicates either nondynamical nature of these degrees or strong couplings. Assuming the former, we integrate out the 2 vector and 2 scalar degrees of freedom. We then find that in the scalar and vector sectors, gauge-invariant variables constructed from metric and matter perturbations have exactly the same quadratic action as in general relativity. The difference from general relativity arises only in the tensor sector, where the graviton mass modifies the dispersion relation of gravitational waves, with a time-dependent effective mass. This may lead to modif...

  6. Geometry of vanishing flow: A new probe to determine the in-medium nucleon–nucleon cross-section

    Indian Academy of Sciences (India)

    Rajiv Chugh; Aman D Sood

    2011-08-01

    We studied the transverse flow throughout the mass range from 20Ne+20Ne to 131Xe+131Xe as a function of the impact parameter. We found that at smaller impact parameters the flow is negative while going through the impact parameter, transverse flow vanishes at a particular colliding geometry named GVF. We found that the mass dependence of GVF is insensitive to the equation of state and momentum-dependent interactions whereas it is quite sensitive to the cross-section. So it can act as a useful tool to pin down the nucleon–nucleon cross-section.

  7. Vanishing of T sub c and appearance of quantum paraelectricity in KD sub 2 PO sub 4 and KH sub 2 PO sub 4 under high pressure

    CERN Document Server

    Endo, S; Tokunaga, M

    2002-01-01

    The temperature dependences of the dielectric constants of the hydrogen-bond ferroelectrics KH sub 2 PO sub 4 (KDP) and KD sub 2 PO sub 4 (DKDP) were measured under high hydrostatic pressure. Their ferroelectric transition temperatures T sub c monotonically decreased with increasing pressure and the ferroelectric state vanished at p sub c : 1.7 GPa for KDP and 6.1 GPa for DKDP. On the other hand, the Curie constant remained finite at p sub c , which indicates that the ferroelectric phase transition at high pressure is of displacive type. At pressures around p sub c , quantum paraelectricity was observed in KDP and DKDP.

  8. Nonlinear pulsation masses

    Energy Technology Data Exchange (ETDEWEB)

    Davis, C.G.

    1990-01-01

    The advent of nonlinear pulsation theory really coincides with the development of the large computers after the second world war. Christy and Stobbie were the first to make use of finite difference techniques on computers to model the bumps'' observed in the classical Cepheid light and velocity curves, the so-called Hertzsprung'' sequence. Following this work a more sophisticated analysis of the light and velocity curves from the models was made by Simon and Davis using Fourier techniques. Recently a simpler amplitude equation formalism has been developed that helps explain this resonance mechanism. The determination of Population I Cepheid masses by nonlinear methods will be discussed. For the lower mass objects, such as RR Lyrae and BL Her. stars, we find general agreement using evolutionary masses and nonlinear pulsation theory. An apparent difficulty of nonlinear pulsation theory occurs in the understanding of double'' mode pulsation, which will also be discussed. Recent studies in nonlinear pulsation theory have dealt with the question of mode selection, period doubling and the trends towards chaotic behavior such as is observed in the transition from W Virginis to RV Tauri-like stars. 10 refs., 1 fig., 2 tabs.

  9. The vanishing limit of the square-well fluid: the adhesive hard-sphere model as a reference system.

    Science.gov (United States)

    Largo, J; Miller, M A; Sciortino, F

    2008-04-07

    We report a simulation study of the gas-liquid critical point for the square-well potential, for values of well width delta as small as 0.005 times the particle diameter sigma. For small delta, the reduced second virial coefficient at the critical point B2*c is found to depend linearly on delta. The observed weak linear dependence is not sufficient to produce any significant observable effect if the critical temperature Tc is estimated via a constant B2*c assumption, due to the highly nonlinear transformation between B2*c and Tc. This explains the previously observed validity of the law of corresponding states. The critical density rho c is also found to be constant when measured in units of the cube of the average distance between two bonded particles (1+0.5 delta)sigma. The possibility of describing the delta-->0 dependence with precise functional forms provides improved accurate estimates of the critical parameters of the adhesive hard-sphere model.

  10. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  11. A scalable nonlinear fluid-structure interaction solver based on a Schwarz preconditioner with isogeometric unstructured coarse spaces in 3D

    Science.gov (United States)

    Kong, Fande; Cai, Xiao-Chuan

    2017-07-01

    Nonlinear fluid-structure interaction (FSI) problems on unstructured meshes in 3D appear in many applications in science and engineering, such as vibration analysis of aircrafts and patient-specific diagnosis of cardiovascular diseases. In this work, we develop a highly scalable, parallel algorithmic and software framework for FSI problems consisting of a nonlinear fluid system and a nonlinear solid system, that are coupled monolithically. The FSI system is discretized by a stabilized finite element method in space and a fully implicit backward difference scheme in time. To solve the large, sparse system of nonlinear algebraic equations at each time step, we propose an inexact Newton-Krylov method together with a multilevel, smoothed Schwarz preconditioner with isogeometric coarse meshes generated by a geometry preserving coarsening algorithm. Here ;geometry; includes the boundary of the computational domain and the wet interface between the fluid and the solid. We show numerically that the proposed algorithm and implementation are highly scalable in terms of the number of linear and nonlinear iterations and the total compute time on a supercomputer with more than 10,000 processor cores for several problems with hundreds of millions of unknowns.

  12. Nonlinear Dynamic Force Spectroscopy

    CERN Document Server

    Björnham, Oscar

    2016-01-01

    Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information of the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear regime. For example, bacterial adhesion pili and polymers with worm-like chain properties are examples of structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory we modeled a bio-complex expressed on a stiff, an elastic and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found th...

  13. Nonlinear optomechanical paddle nanocavities

    CERN Document Server

    Kaviani, Hamidreza; Wu, Marcelo; Ghobadi, Roohollah; Barclay, Paul E

    2014-01-01

    A photonic crystal optomechanical system combining strong nonlinear optomechanical coupling, low effective mass and large optical mode spacing is introduced. This nanoscale "paddle nanocavity" device supports mechanical resonances with effective mass of 300--600 fg which couple nonlinearly to co-localized optical modes with a quadratic optomechanical coupling coefficient $g^{(2)} > 2\\pi\\times400$ MHz/nm$^2$, and a two phonon to single photon optomechanical coupling rate $\\Delta \\omega_0 > 2\\pi\\times 16$ Hz. This coupling relies on strong phonon-photon interactions in a structure whose optical mode spectrum is highly non--degenerate. Simulations indicate that nonlinear optomechanical readout of thermally driven motion in these devices should be observable for T $> 50 $ mK, and that measurement of phonon shot noise is achievable.

  14. Nonlinear dynamics of structures

    CERN Document Server

    Oller, Sergio

    2014-01-01

    This book lays the foundation of knowledge that will allow a better understanding of nonlinear phenomena that occur in structural dynamics.   This work is intended for graduate engineering students who want to expand their knowledge on the dynamic behavior of structures, specifically in the nonlinear field, by presenting the basis of dynamic balance in non‐linear behavior structures due to the material and kinematics mechanical effects.   Particularly, this publication shows the solution of the equation of dynamic equilibrium for structure with nonlinear time‐independent materials (plasticity, damage and frequencies evolution), as well as those time dependent non‐linear behavior materials (viscoelasticity and viscoplasticity). The convergence conditions for the non‐linear dynamic structure solution  are studied, and the theoretical concepts and its programming algorithms are presented.  

  15. Nonlinear Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Hansen, Kim Per

    2004-01-01

    , leading to reduced mode confinement and dispersion flexibility. In this thesis, we treat the nonlinear photonic crystal fiber – a special sub-class of photonic crystal fibers, the core of which has a diameter comparable to the wavelength of the light guided in the fiber. The small core results in a large...... nonlinear coefficient and in various applications, it is therefore possible to reduce the required fiber lengths quite dramatically, leading to increased stability and efficiency. Furthermore, it is possible to design these fibers with zero-dispersion at previously unreachable wavelengths, paving the way...... for completely new applications, especially in and near the visible wavelength region. One such application is supercontinuum generation. Supercontinuum generation is extreme broadening of pulses in a nonlinear medium (in this case a small-core fiber), and depending on the dispersion of the fiber, it is possible...

  16. Linearizing nonlinear optics

    CERN Document Server

    Schmidt, Bruno E; Ernotte, Guilmot; Clerici, Matteo; Morandotti, Roberto; Ibrahim, Heide; Legare, Francois

    2016-01-01

    In the framework of linear optics, light fields do not interact with each other in a medium. Yet, when their field amplitude becomes comparable to the electron binding energies of matter, the nonlinear motion of these electrons emits new dipole radiation whose amplitude, frequency and phase differ from the incoming fields. Such high fields are typically achieved with ultra-short, femtosecond (1fs = 10-15 sec.) laser pulses containing very broad frequency spectra. Here, the matter not only couples incoming and outgoing fields but also causes different spectral components to interact and mix through a convolution process. In this contribution, we describe how frequency domain nonlinear optics overcomes the shortcomings arising from this convolution in conventional time domain nonlinear optics1. We generate light fields with previously inaccessible properties because the uncontrolled coupling of amplitudes and phases is turned off. For example, arbitrary phase functions are transferred linearly to the second har...

  17. Nonlinear optomechanics with graphene

    Science.gov (United States)

    Shaffer, Airlia; Patil, Yogesh Sharad; Cheung, Hil F. H.; Wang, Ke; Vengalattore, Mukund

    2016-05-01

    To date, studies of cavity optomechanics have been limited to exploiting the linear interactions between the light and mechanics. However, investigations of quantum signal transduction, quantum enhanced metrology and manybody physics with optomechanics each require strong, nonlinear interactions. Graphene nanomembranes are an exciting prospect for realizing such studies due to their inherently nonlinear nature and low mass. We fabricate large graphene nanomembranes and study their mechanical and optical properties. By using dark ground imaging techniques, we correlate their eigenmode shapes with the measured dissipation. We study their hysteretic response present even at low driving amplitudes, and their nonlinear dissipation. Finally, we discuss ongoing efforts to use these resonators for studies of quantum optomechanics and force sensing. This work is supported by the DARPA QuASAR program through a Grant from the ARO.

  18. Nonlinear Analysis of Buckling

    Directory of Open Access Journals (Sweden)

    Psotný Martin

    2014-06-01

    Full Text Available The stability analysis of slender web loaded in compression was presented. To solve this problem, a specialized computer program based on FEM was created. The nonlinear finite element method equations were derived from the variational principle of minimum of potential energy. To obtain the nonlinear equilibrium paths, the Newton-Raphson iteration algorithm was used. Corresponding levels of the total potential energy were defined. The peculiarities of the effects of the initial imperfections were investigated. Special attention was focused on the influence of imperfections on the post-critical buckling mode. The stable and unstable paths of the nonlinear solution were separated. Obtained results were compared with those gained using ANSYS system.

  19. Nonlinear Metamaterials for Holography

    CERN Document Server

    Almeida, Euclides; Prior, Yehiam

    2015-01-01

    A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multi-layer metamaterial holograms where by the nonlinear process of Third Harmonic Generation, a background free image is formed at a new frequency which is the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analyzed and prospects for future device applications are discussed.

  20. Multidimensional nonlinear descriptive analysis

    CERN Document Server

    Nishisato, Shizuhiko

    2006-01-01

    Quantification of categorical, or non-numerical, data is a problem that scientists face across a wide range of disciplines. Exploring data analysis in various areas of research, such as the social sciences and biology, Multidimensional Nonlinear Descriptive Analysis presents methods for analyzing categorical data that are not necessarily sampled randomly from a normal population and often involve nonlinear relations. This reference not only provides an overview of multidimensional nonlinear descriptive analysis (MUNDA) of discrete data, it also offers new results in a variety of fields. The first part of the book covers conceptual and technical preliminaries needed to understand the data analysis in subsequent chapters. The next two parts contain applications of MUNDA to diverse data types, with each chapter devoted to one type of categorical data, a brief historical comment, and basic skills peculiar to the data types. The final part examines several problems and then concludes with suggestions for futu...

  1. Nonlinear airship aeroelasticity

    Science.gov (United States)

    Bessert, N.; Frederich, O.

    2005-12-01

    The aeroelastic derivatives for today's aircraft are calculated in the concept phase using a standard procedure. This scheme has to be extended for large airships, due to various nonlinearities in structural and aerodynamic behaviour. In general, the structural model of an airship is physically as well as geometrically nonlinear. The main sources of nonlinearity are large deformations and the nonlinear material behaviour of membranes. The aerodynamic solution is also included in the nonlinear problem, because the deformed airship influences the surrounding flow. Due to these nonlinearities, the aeroelastic problem for airships can only be solved by an iterative procedure. As one possibility, the coupled aerodynamic and structural dynamic problem was handled using linked standard solvers. On the structural side, the Finite-Element program package ABAQUS was extended with an interface to the aerodynamic solver VSAERO. VSAERO is based on the aerodynamic panel method using potential flow theory. The equilibrium of the internal structural and the external aerodynamic forces leads to the structural response and a trimmed flight state for the specified flight conditions (e.g. speed, altitude). The application of small perturbations around a trimmed state produces reaction forces and moments. These constraint forces are then transferred into translational and rotational acceleration fields by performing an inertia relief analysis of the disturbed structural model. The change between the trimmed flight state and the disturbed one yields the respective aeroelastic derivatives. By including the calculated derivatives in the linearised equation of motion system, it is possible to judge the stability and controllability of the investigated airship.

  2. Nonlinear fiber optics

    CERN Document Server

    Agrawal, Govind

    2012-01-01

    Since the 4e appeared, a fast evolution of the field has occurred. The 5e of this classic work provides an up-to-date account of the nonlinear phenomena occurring inside optical fibers, the basis of all our telecommunications infastructure as well as being used in the medical field. Reflecting the big developments in research, this new edition includes major new content: slow light effects, which offers a reduction in noise and power consumption and more ordered network traffic-stimulated Brillouin scattering; vectorial treatment of highly nonlinear fibers; and a brand new chapter o

  3. Limits to Nonlinear Inversion

    DEFF Research Database (Denmark)

    Mosegaard, Klaus

    2012-01-01

    For non-linear inverse problems, the mathematical structure of the mapping from model parameters to data is usually unknown or partly unknown. Absence of information about the mathematical structure of this function prevents us from presenting an analytical solution, so our solution depends on our......-heuristics are inefficient for large-scale, non-linear inverse problems, and that the 'no-free-lunch' theorem holds. We discuss typical objections to the relevance of this theorem. A consequence of the no-free-lunch theorem is that algorithms adapted to the mathematical structure of the problem perform more efficiently than...

  4. Fundamentals of nonlinear optics

    CERN Document Server

    Powers, Peter E

    2011-01-01

    Peter Powers's rigorous but simple description of a difficult field keeps the reader's attention throughout. … All chapters contain a list of references and large numbers of practice examples to be worked through. … By carefully working through the proposed problems, students will develop a sound understanding of the fundamental principles and applications. … the book serves perfectly for an introductory-level course for second- and third-order nonlinear optical phenomena. The author's writing style is refreshing and original. I expect that Fundamentals of Nonlinear Optics will fast become pop

  5. Tunable nonlinear graphene metasurfaces

    CERN Document Server

    Smirnova, Daria A; Kivshar, Yuri S; Khanikaev, Alexander B

    2015-01-01

    We introduce the concept of nonlinear graphene metasurfaces employing the controllable interaction between a graphene layer and a planar metamaterial. Such hybrid metasurfaces support two types of subradiant resonant modes, asymmetric modes of structured metamaterial elements ("metamolecules") and graphene plasmons exhibiting strong mutual coupling and avoided dispersion crossing. High tunability of graphene plasmons facilitates strong interaction between the subradiant modes, modifying the spectral position and lifetime of the associated Fano resonances. We demonstrate that strong resonant interaction, combined with the subwavelength localization of plasmons, leads to the enhanced nonlinear response and high efficiency of the second-harmonic generation.

  6. Nonlinear effects in optical fibers

    CERN Document Server

    Ferreira, Mario F

    2011-01-01

    Cutting-edge coverage of nonlinear phenomena occurring inside optical fibers Nonlinear fiber optics is a specialized part of fiber optics dealing with optical nonlinearities and their applications. As fiber-optic communication systems have become more advanced and complex, the nonlinear effects in optical fibers have increased in importance, as they adversely affect system performance. Paradoxically, the same nonlinear phenomena also offer the promise of addressing the bandwidth bottleneck for signal processing for future ultra-high speed optical networks. Nonlinear Effects in Optical Fiber

  7. Analytical and numerical investigation of nonlinear internal gravity waves

    Directory of Open Access Journals (Sweden)

    S. P. Kshevetskii

    2001-01-01

    Full Text Available The propagation of long, weakly nonlinear internal waves in a stratified gas is studied. Hydrodynamic equations for an ideal fluid with the perfect gas law describe the atmospheric gas behaviour. If we neglect the term Ͽ dw/dt (product of the density and vertical acceleration, we come to a so-called quasistatic model, while we name the full hydro-dynamic model as a nonquasistatic one. Both quasistatic and nonquasistatic models are used for wave simulation and the models are compared among themselves. It is shown that a smooth classical solution of a nonlinear quasistatic problem does not exist for all t because a gradient catastrophe of non-linear internal waves occurs. To overcome this difficulty, we search for the solution of the quasistatic problem in terms of a generalised function theory as a limit of special regularised equations containing some additional dissipation term when the dissipation factor vanishes. It is shown that such solutions of the quasistatic problem qualitatively differ from solutions of a nonquasistatic nature. It is explained by the fact that in a nonquasistatic model the vertical acceleration term plays the role of a regularizator with respect to a quasistatic model, while the solution qualitatively depends on the regularizator used. The numerical models are compared with some analytical results. Within the framework of the analytical model, any internal wave is described as a system of wave modes; each wave mode interacts with others due to equation non-linearity. In the principal order of a perturbation theory, each wave mode is described by some equation of a KdV type. The analytical model reveals that, in a nonquasistatic model, an internal wave should disintegrate into solitons. The time of wave disintegration into solitons, the scales and amount of solitons generated are important characteristics of the non-linear process; they are found with the help of analytical and numerical investigations. Satisfactory

  8. Nonlinear elliptic systems with exponential nonlinearities

    Directory of Open Access Journals (Sweden)

    Said El Manouni

    2002-12-01

    Full Text Available In this paper we investigate the existence of solutions for {gather*} -mathop{m div}( a(| abla u | ^N| abla u |^{N-2}u = f(x,u,v quad mbox{in } Omega -mathop{m div}(a(| abla v| ^N| abla v |^{N-2}v = g(x,u,v quad mbox{in } Omega u(x = v(x = 0 quad mbox{on }partial Omega. end{gather*} Where $Omega$ is a bounded domain in ${mathbb{R}}^N$, $Ngeq 2$, $f$ and $g$ are nonlinearities having an exponential growth on $Omega$ and $a$ is a continuous function satisfying some conditions which ensure the existence of solutions.

  9. Nonlinearity and disorder: Classification and stability of nonlinear impurity modes

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole

    2001-01-01

    We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of no...

  10. Generalized Nonlinear Yule Models

    Science.gov (United States)

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-10-01

    With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.

  11. Nonlinear Regression with R

    CERN Document Server

    Ritz, Christian; Parmigiani, Giovanni

    2009-01-01

    R is a rapidly evolving lingua franca of graphical display and statistical analysis of experiments from the applied sciences. This book provides a coherent treatment of nonlinear regression with R by means of examples from a diversity of applied sciences such as biology, chemistry, engineering, medicine and toxicology.

  12. Methods of nonlinear kinetics

    OpenAIRE

    Gorban, A. N.; Karlin, I.V.

    2003-01-01

    Nonlinear kinetic equations are reviewed for a wide audience of specialists and postgraduate students in physics, mathematical physics, material science, chemical engineering and interdisciplinary research. Contents: The Boltzmann equation, Phenomenology and Quasi-chemical representation of the Boltzmann equation, Kinetic models, Discrete velocity models, Direct simulation, Lattice Gas and Lattice Boltzmann models, Minimal Boltzmann models for flows at low Knudsen number, Other kinetic equati...

  13. Intramolecular and nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Davis, M.J. [Argonne National Laboratory, IL (United States)

    1993-12-01

    Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.

  14. Nonlinear Hamiltonian systems

    DEFF Research Database (Denmark)

    Jørgensen, Michael Finn

    1995-01-01

    It is generally very difficult to solve nonlinear systems, and such systems often possess chaotic solutions. In the rare event that a system is completely solvable, it is said to integrable. Such systems never have chaotic solutions. Using the Inverse Scattering Transform Method (ISTM) two...

  15. Nonlinear phased array imaging

    Science.gov (United States)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  16. Generalized Nonlinear Yule Models

    Science.gov (United States)

    Lansky, Petr; Polito, Federico; Sacerdote, Laura

    2016-11-01

    With the aim of considering models related to random graphs growth exhibiting persistent memory, we propose a fractional nonlinear modification of the classical Yule model often studied in the context of macroevolution. Here the model is analyzed and interpreted in the framework of the development of networks such as the World Wide Web. Nonlinearity is introduced by replacing the linear birth process governing the growth of the in-links of each specific webpage with a fractional nonlinear birth process with completely general birth rates. Among the main results we derive the explicit distribution of the number of in-links of a webpage chosen uniformly at random recognizing the contribution to the asymptotics and the finite time correction. The mean value of the latter distribution is also calculated explicitly in the most general case. Furthermore, in order to show the usefulness of our results, we particularize them in the case of specific birth rates giving rise to a saturating behaviour, a property that is often observed in nature. The further specialization to the non-fractional case allows us to extend the Yule model accounting for a nonlinear growth.

  17. Trirefringence in nonlinear metamaterials

    CERN Document Server

    De Lorenci, Vitorio A

    2012-01-01

    We study the propagation of electromagnetic waves in the limit of geometrical optics for a class of nearly transparent nonlinear uniaxial metamaterials for which their permittivity tensors present a negative principal component. Their permeability are assumed positive and dependent on the electric field. We show that light waves experience triple refraction -- trirefringence. Additionally to the ordinary wave, two extraordinary waves propagate in such media.

  18. Nonlinear silicon photonics

    Science.gov (United States)

    Borghi, M.; Castellan, C.; Signorini, S.; Trenti, A.; Pavesi, L.

    2017-09-01

    Silicon photonics is a technology based on fabricating integrated optical circuits by using the same paradigms as the dominant electronics industry. After twenty years of fervid development, silicon photonics is entering the market with low cost, high performance and mass-manufacturable optical devices. Until now, most silicon photonic devices have been based on linear optical effects, despite the many phenomenologies associated with nonlinear optics in both bulk materials and integrated waveguides. Silicon and silicon-based materials have strong optical nonlinearities which are enhanced in integrated devices by the small cross-section of the high-index contrast silicon waveguides or photonic crystals. Here the photons are made to strongly interact with the medium where they propagate. This is the central argument of nonlinear silicon photonics. It is the aim of this review to describe the state-of-the-art in the field. Starting from the basic nonlinearities in a silicon waveguide or in optical resonator geometries, many phenomena and applications are described—including frequency generation, frequency conversion, frequency-comb generation, supercontinuum generation, soliton formation, temporal imaging and time lensing, Raman lasing, and comb spectroscopy. Emerging quantum photonics applications, such as entangled photon sources, heralded single-photon sources and integrated quantum photonic circuits are also addressed at the end of this review.

  19. Nonlinear fibre optics overview

    DEFF Research Database (Denmark)

    Travers, J. C.; Frosz, Michael Henoch; Dudley, J. M.

    2010-01-01

    , provides a background to the associated nonlinear optical processes, treats the generation mechanisms from continuous wave to femtosecond pulse pump regimes and highlights the diverse applications. A full discussion of numerical methods and comprehensive computer code are also provided, enabling readers...

  20. Nonlinear silicon photonics

    Science.gov (United States)

    Tsia, Kevin K.; Jalali, Bahram

    2010-05-01

    An intriguing optical property of silicon is that it exhibits a large third-order optical nonlinearity, with orders-ofmagnitude larger than that of silica glass in the telecommunication band. This allows efficient nonlinear optical interaction at relatively low power levels in a small footprint. Indeed, we have witnessed a stunning progress in harnessing the Raman and Kerr effects in silicon as the mechanisms for enabling chip-scale optical amplification, lasing, and wavelength conversion - functions that until recently were perceived to be beyond the reach of silicon. With all the continuous efforts developing novel techniques, nonlinear silicon photonics is expected to be able to reach even beyond the prior achievements. Instead of providing a comprehensive overview of this field, this manuscript highlights a number of new branches of nonlinear silicon photonics, which have not been fully recognized in the past. In particular, they are two-photon photovoltaic effect, mid-wave infrared (MWIR) silicon photonics, broadband Raman effects, inverse Raman scattering, and periodically-poled silicon (PePSi). These novel effects and techniques could create a new paradigm for silicon photonics and extend its utility beyond the traditionally anticipated applications.