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Equilibrium Distribution (equilibrium + distribution)
Selected AbstractsEquilibrium Wage-Tenure ContractsECONOMETRICA, Issue 5 2003Ken Burdett In this study we consider a labor market matching model where firms post wage-tenure contracts and workers, both employed and unemployed, search for new job opportunities. Given workers are risk averse, we establish there is a unique equilibrium in the environment considered. Although firms in the market make different offers in equilibrium, all post a wage-tenure contract that implies a worker's wage increases smoothly with tenure at the firm. As firms make different offers, there is job turnover, as employed workers move jobs as the opportunity arises. This implies the increase in a worker's wage can be due to job-to-job movements as well as wage-tenure effects. Further, there is a nondegenerate equilibrium distribution of initial wage offers that is differentiable on its support except for a mass point at the lowest initial wage. We also show that relevant characteristics of the equilibrium can be written as explicit functions of preferences and the other market parameters. [source] Dynamic coupled metal transport-speciation model: Application to assess a zinc-contaminated lakeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2004Satyendra P. Bhavsar Abstract A coupled metal transport and speciation/complexation model (TRANSPEC) has been developed to estimate the speciation and fate of multiple interconverting species in surface aquatic systems. Dynamic-TRANSPEC loosely, sequentially couples the speciation/complexation and fate modules that, for the unsteady state formulation, run alternatively at every time step. The speciation module first estimates species abundance using, in this version, MINEQL+ considering time-dependent changes in water and pore-water chemistry. The fate module is based on the quantitative water air sediment interaction (QWASI) model and fugacity/aquivalence formulation, with the option of using a pseudo-steady state solution to account for past discharges. Similarly to the QWASI model for organic contaminants, TRANSPEC assumes the instantaneous equilibrium distribution of metal species among dissolved, colloidal, and particulate phases based on ambient chemistry parameters that can be collected through conventional field methods. The model is illustrated with its application to Ross Lake (Manitoba, Canada) that has elevated Zn concentrations due to discharges over 70 years from a mining operation. Using measurements from field studies, the model reproduces year-round variations in Zn water concentrations. A 10-year projection for current conditions suggests decreasing Zn remobilization and export from the lake. Decreasing Zn loadings increases sediment-to-water transport but decreases water concentrations, and vice versa. Species distribution is affected by pH such that a decrease in pH increases metal export from the lake and vice versa. [source] Convergence in West German Regional Unemployment RatesGERMAN ECONOMIC REVIEW, Issue 4 2007Christian Bayer Stochastic convergence; unemployment; structural break; unit root Abstract. Differences in regional unemployment rates are often used to describe regional economic inequality. This paper asks whether changes in regional unemployment differences in West Germany are persistent over time. Understanding the persistency of regional unemployment differences helps us to assess how effective regional policy can be. While univariate tests suggest that changes in regional unemployment differences are persistent in West Germany, more powerful panel tests lend some support to the hypothesis that regional unemployment rates converge. However, these tests reveal a moderate speed of convergence at best. Because there is a structural break following the second oil crisis, we also use tests that allow for such a break. This provides evidence for both convergence and quick adjustment to an equilibrium distribution of regional unemployment rates that is, however, subject to a structural break. [source] Simulation of shockwave propagation with a thermal lattice Boltzmann modelINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2003ShiDe Feng Abstract A two-dimensional 19-velocity (D2Q19) lattice Boltzmann model which satisfies the conservation laws governing the macroscopic and microscopic mass, momentum and energy with local equilibrium distribution order O(u4) rather than the usual O(u3) has been developed. This model is applied to simulate the reflection of shockwaves on the surface of a triangular obstacle. Good qualitative agreement between the numerical predictions and experimental measurements is obtained. As the model contains the higher-order terms in the local equilibrium distribution, it performs much better in terms of numerical accuracy and stability than the earlier 13-velocity models with the local equilibrium distribution accurate only up to the second order in the velocity u. Copyright © 2003 John Wiley & Sons, Ltd. [source] Modelling the interplay between pest movement and the physical design of trap crop systemsAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2005Salla Hannunen Abstract, 1,The interplay between pest movement and trap crop physical design is modelled in a situation where the pest moves by a random walk with spatially variable mobility. Questions addressed are: (i) how does the proportion of trap crop area of the total field area influence the equilibrium distribution of pests among the crop and the trap crop and (ii) how do crop patch size and shape influence the speed of pest redistribution from the crop to the trap crop. 2,When pest mobility in the trap crop is clearly lower than that in the crop, the pest population in the crop decreases very sharply for small trap crop proportions. When mobility in the trap crop is slightly closer to that in the crop, the pest population in the crop decreases much more gradually with increasing trap crop proportion. Thus finding a trap crop that the pest distinctly prefers over the crop appears to be crucial for developing efficient trap crop systems. 3,The rate of decay in the pest population in the crop increases with increasing perimeter to area ratio of the crop patch. Hence, designing field layouts to increase the perimeter to area ratio of crop patches may be beneficial. [source] Microemulsion copolymerization of styrene and acrylonitrile with n -butanol as the cosurfactantJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2005Yuanchang Shi Abstract The microemulsion copolymerization of styrene and acrylonitrile in an n -butanol/cetyltrimethylammonium bromide/oil/water microemulsion system was studied. The solubilization sites of the two monomers were determined with an NMR technique. The results showed that the solubilization behaviors of the two monomers were quite different. Most of the styrene was solubilized in the palisade layer of the microemulsion, whereas the acrylonitrile had an equilibrium distribution in the aqueous phase and palisade layer of the microemulsion. The reactivity ratios of styrene and acrylonitrile in the microemulsion system were different from those in other media. The effect of the monomer feed composition on the copolymerization kinetics was investigated, and the mechanism of nucleation of the latex particles was examined. The experimental results showed that the copolymerization loci were changed from the microemulsion droplets to the aqueous phase when the concentration of acrylonitrile in the monomer feed reached approximately 80%; this could be further proved by the effect of the monomer feed composition on the copolymerization kinetics. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 203,216, 2005 [source] Aluminium-27 NMR investigation of the influence of cation type on aluminosilicate solutionsMAGNETIC RESONANCE IN CHEMISTRY, Issue 10 2002Naser Azizi Abstract The effects of tetraalkylammonium (TAA) and alkali metal cations on the equilibrium distribution of aluminosilicate oligomers in aqueous alkaline aluminosilicate solutions were investigated using 27Al NMR spectra and their evolution with time. The results indicate that there are no differences in the initial equilibria involving solutions containing both TAA and alkali metal cations on the one hand and those containing alkali metal cations only. However, re-equilibration of the aluminosilicate species for TAA/Na aluminosilicates is slow (usually not detectable on the time-scale of the experiments), whereas when purely alkali metal cations are used, the spectra alter over a period of ,1 h, such that resolution is degraded substantially. In the latter case, it is suggested that the anions aggregate into larger systems, although the solutions are still clear. 29Si NMR evidence for slow equilibration of silicate and aluminosilicate solutions at higher concentrations is also discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] SUSTAINABLE YIELDS IN FISHERIES: UNCERTAINTY, RISK-AVERSION, AND MEAN-VARIANCE ANALYSISNATURAL RESOURCE MODELING, Issue 3 2010CHRISTIAN-OLIVER EWALD Abstract We consider a model of a fishery in which the dynamics of the unharvested fish population are given by the stochastic logistic growth equation Similar to the classical deterministic analogon, we assume that the fishery harvests the fish population following a constant effort strategy. In the first step, we derive the effort level that leads to maximum expected sustainable yield, which is understood as the expectation of the equilibrium distribution of the stochastic dynamics. This replaces the nonzero fixed point in the classical deterministic setup. In the second step, we assume that the fishery is risk averse and that there is a tradeoff between expected sustainable yield and uncertainty measured in terms of the variance of the equilibrium distribution. We derive the optimal constant effort harvesting strategy for this problem. In the final step, we consider an approach that we call the mean-variance analysis to sustainable fisheries. Similar as in the now classical mean-variance analysis in finance, going back to Markowitz [1952], we study the problem of maximizing expected sustainable yields under variance constraints, and with this, minimizing the variance, e.g., risk, under guaranteed minimum expected sustainable yields. We derive explicit formulas for the optimal fishing effort in all four problems considered and study the effects of uncertainty, risk aversion, and mean reversion speed on fishing efforts. [source] Manifestation of the equilibrium hole distribution in photoluminescence of n-InNPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2005A. A. Klochikhin Abstract Photoluminescence (PL) of n-InN grown by molecular beam epitaxy with Hall concentrations from 3.6 to 7.3 × 1017 cm,3 demonstrates dependences on carrier concentration, temperature, and excitation density which give evidences of a fast energy relaxation rate of photoholes and their equilibrium distribution over localized states. The structure of the PL spectra observed at 4.2 and 77 K in the energy interval from 0.50 to 0.67 eV indicates that a considerable part of holes is trapped by deep and shallow acceptors before the interband recombi- nation with degenerate electrons occurs. At room temperature, the band-to-band recombination of free holes and electrons dominates in PL. Experimental results on PL and absorption are described by model calculations under the assumptions of a band gap equal to 0.665,0.670 eV at zero temperature and zero carrier concentration and a non-parabolic conduction band with the effective mass at the G -point equal to 0.07 of the free electron mass. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] FX Trading and Exchange Rate DynamicsTHE JOURNAL OF FINANCE, Issue 6 2002Martin D. D. Evans I examine the sources of exchange rate dynamics by focusing on the information structure of FX trading. This structure permits the existence of an equilibrium distribution of transaction prices at a point in time. I develop and estimate a model of the price distribution using data from the Deutsche mark/dollar market that prroduces two striking results:(1) Much of the short-term volatility in exchange rates comes from sampling the heterogeneous trading decisions of dealers in a distribution that, under normal market conditions, changes comparatively slowly; (2) public news is rarely the predominant source of exchange rate movements over anyhorizon. [source] ON THE ROBUSTNESS OF PRIVATE LEADERSHIP IN MIXED DUOPOLYAUSTRALIAN ECONOMIC PAPERS, Issue 2 2010TOSHIHIRO MATSUMURA We investigate a mixed duopoly where a state-owned public enterprise competes against a profit-maximising private enterprise. We analyse whether private leadership or public leadership is robust in the observable delay game. We find that private leadership is always risk dominant. We also investigate how ownership structure in a public firm affects the equilibrium distribution of roles. We find that the roles are as follows: (1) Cournot, when the degree of privatisation is low, (2) private leadership, when it is middle, (3) both private leadership and public leadership, when it is high. The result implies that private leadership is again more robust. [source] Continuum molecular electrostatics, salt effects, and counterion binding,A review of the Poisson,Boltzmann theory and its modificationsBIOPOLYMERS, Issue 2 2008Grochowski Abstract This work is a review of the Poisson,Boltzmann (PB) continuum electrostatics theory and its modifications, with a focus on salt effects and counterion binding. The PB model is one of the mesoscopic theories that describes the electrostatic potential and equilibrium distribution of mobile ions around molecules in solution. It serves as a tool to characterize electrostatic properties of molecules, counterion association, electrostatic contributions to solvation, and molecular binding free energies. We focus on general formulations which can be applied to large molecules of arbitrary shape in all-atomic representation, including highly charged biomolecules such as nucleic acids. These molecules present a challenge for theoretical description, because the conventional PB model may become insufficient in those cases. We discuss the conventional PB equation, the corresponding functionals of the electrostatic free energy, including a connection to DFT, simple empirical extensions to this model accounting for finite size of ions, the modified PB theory including ionic correlations and fluctuations, the cell model, and supplementary methods allowing to incorporate site-bound ions in the PB calculations. © 2007 Wiley Periodicals, Inc. Biopolymers 89: 93,113, 2008. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Ground-State Equilibrium Thermodynamics and Switching Kinetics of Bistable [2]Rotaxanes Switched in Solution, Polymer Gels, and Molecular Electronic DevicesCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2006Jang Wook Choi Abstract We report on the kinetics and ground-state thermodynamics associated with electrochemically driven molecular mechanical switching of three bistable [2]rotaxanes in acetonitrile solution, polymer electrolyte gels, and molecular-switch tunnel junctions (MSTJs). For all rotaxanes a ,-electron-deficient cyclobis(paraquat- p -phenylene) (CBPQT4+) ring component encircles one of two recognition sites within a dumbbell component. Two rotaxanes (RATTF4+ and RTTF4+) contain tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) recognition units, but different hydrophilic stoppers. For these rotaxanes, the CBPQT4+ ring encircles predominantly (>90,%) the TTF unit at equilibrium, and this equilibrium is relatively temperature independent. In the third rotaxane (RBPTTF4+), the TTF unit is replaced by a ,-extended analogue (a bispyrrolotetrathiafulvalene (BPTTF) unit), and the CBPQT4+ ring encircles almost equally both recognition sites at equilibrium. This equilibrium exhibits strong temperature dependence. These thermodynamic differences were rationalized by reference to binding constants obtained by isothermal titration calorimetry for the complexation of model guests by the CBPQT4+ host in acetonitrile. For all bistable rotaxanes, oxidation of the TTF (BPTTF) unit is accompanied by movement of the CBPQT4+ ring to the DNP site. Reduction back to TTF0 (BPTTF0) is followed by relaxation to the equilibrium distribution of translational isomers. The relaxation kinetics are strongly environmentally dependent, yet consistent with a single electromechanical-switching mechanism in acetonitrile, polymer electrolyte gels, and MSTJs. The ground-state equilibrium properties of all three bistable [2]rotaxanes were reflective of molecular structure in all environments. These results provide direct evidence for the control by molecular structure of the electronic properties exhibited by the MSTJs. [source] Pathwise accuracy and ergodicity of metropolized integrators for SDEsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 5 2010Nawaf Bou-Rabee Metropolized integrators for ergodic stochastic differential equations (SDEs) are proposed that (1) are ergodic with respect to the (known) equilibrium distribution of the SDEs and (2) approximate pathwise the solutions of the SDEs on finite-time intervals. Both these properties are demonstrated in the paper, and precise strong error estimates are obtained. It is also shown that the Metropolized integrator retains these properties even in situations where the drift in the SDE is nonglobally Lipschitz, and vanilla explicit integrators for SDEs typically become unstable and fail to be ergodic. © 2009 Wiley Periodicals, Inc. [source] The geometric minimum action method: A least action principle on the space of curvesCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 8 2008Matthias Heymann Freidlin-Wentzell theory of large deviations for the description of the effect of small random perturbations on dynamical systems is exploited as a numerical tool. Specifically, a numerical algorithm is proposed to compute the quasi-potential in the theory, which is the key object to quantify the dynamics on long time scales when the effect of the noise becomes ubiquitous: the equilibrium distribution of the system, the pathways of transition between metastable states and their rate, etc., can all be expressed in terms of the quasi-potential. We propose an algorithm to compute these quantities called the geometric minimum action method (gMAM), which is a blend of the original minimum action method (MAM) and the string method. It is based on a reformulation of the large deviations action functional on the space of curves that allows one to easily perform the double minimization of the original action required to compute the quasi-potential. The theoretical background of the gMAM in the context of large deviations theory is discussed in detail, as well as the algorithmic aspects of the method. The gMAM is then illustrated on several examples: a finite-dimensional system displaying bistability and modeled by a nongradient stochastic ordinary differential equation, an infinite-dimensional analogue of this system modeled by a stochastic partial differential equation, and an example of a bistable genetic switch modeled by a Markov jump process. © 2007 Wiley Periodicals, Inc. [source] Chain graph models and their causal interpretations,JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES B (STATISTICAL METHODOLOGY), Issue 3 2002Steffen L. Lauritzen Chain graphs are a natural generalization of directed acyclic graphs and undirected graphs. However, the apparent simplicity of chain graphs belies the subtlety of the conditional independence hypotheses that they represent. There are many simple and apparently plausible, but ultimately fallacious, interpretations of chain graphs that are often invoked, implicitly or explicitly. These interpretations also lead to flawed methods for applying background knowledge to model selection. We present a valid interpretation by showing how the distribution corresponding to a chain graph may be generated from the equilibrium distributions of dynamic models with feed-back. These dynamic interpretations lead to a simple theory of intervention, extending the theory developed for directed acyclic graphs. Finally, we contrast chain graph models under this interpretation with simultaneous equation models which have traditionally been used to model feed-back in econometrics. [source] | |||||||||||||||||||