Board structure and firm technical efficiency: Evidence from Canadian state-owned enterprises

The objective of the study is to analyze the board–performance relationship for a group of 14 Canadian SOEs. This context is unique because SOEs do not have major control devices other than the board. As the interaction effect, if any, between the board and other corporate governance structures is expected to be low, we do not have to fully control for the potential impact of different control devices, or to disentangle them completely from influencing board composition. The performance is also measured using data envelopment analysis (DEA), a linear programming method used for the first time in this research area. As such, this study contributes to the operational research literature while applying DEA method to untraditional fields of research.     

Time scale symplectic systems without normality

We present a theory of the definiteness (nonnegativity and positivity) of a quadratic functional F over a bounded time scale. The results are given in terms of a time scale symplectic system (S), which is a time scale linear system that generalizes and unifies the linear Hamiltonian differential system and discrete symplectic system. The novelty of this paper resides in removing the assumption of normality in the characterization of the positivity of F, and in establishing equivalent conditions for the nonnegativity of F without any normality assumption. To reach this goal, a new notion of generalized focal points for conjoined bases (X,U) of (S) is introduced, results on the piecewise-constant kernel of X(t) are obtained, and various Picone-type identities are derived under the piecewise-constant kernel condition. The results of this paper generalize and unify recent ones in each of the discrete and continuous time setting, and constitute a keystone for further development in this theory.     

Generalized Jacobian for Functions with Infinite Dimensional Range and Domain

In this paper, locally Lipschitz functions acting between infinite dimensional normed spaces are considered. When the range is a dual space and satisfies the Radon–Nikodym property, Clarke’s generalized Jacobian will be extended to this setting. Characterization and fundamental properties of the extended generalized Jacobian are established including the nonemptiness, the β-compactness, the β-upper semicontinuity, and a mean-value theorem. A connection with known notions is provided and chain rules are proved using key results developed. This included the vectorization and restriction theorem, and the extension theorem. Therefore, the generalized Jacobian introduced in this paper is proved to enjoy all the properties required of a derivative like-set. Research of the first author is supported by the Hungarian Scientific Research Fund (OKTA) under grant K62316. Research of the second author is supported by the National Science Foundation under grant DMS-0306260.     

Strong Local Optimality Conditions for State Constrained Control Problems

In this paper first- and second-order optimality conditions for strong local minimum are presented for optimal control problems with pure state set-inclusion constraints. The first-order condition is of Pontryagin type, while the second-order condition is of the form of an accessory problem associated with the strong local minimality. This latter condition contains an extra term reflecting the presence of the pure state constraints.     

Equivalent conditions to the nonnegativity of a quadratic functional in discrete optimal control

In this paper we provide a characterization of the nonnegativity of a discrete quadratic functional ? with fixed right endpoint in the optimal control setting. This characterization is closely related to the kernel condition earlier introduced by M. Bohner as a part of a focal points definition for conjoined bases of the associated linear Hamiltonian difference system. When this kernel condition is satisfied only up to a certain critical index m, the traditional conditions, which are the focal points, conjugate intervals, implicit Riccati equation, and partial quadratic functionals, must be replaced by a new condition. This new condition is determined to be the nonnegativity of a block tridiagonal matrix, representing the remainder of ? after the index m, on a suitable subspace. Applications of our result include the discrete Jacobi condition, a unification of the nonnegativity and positivity of ? into one statement, and an improved result for the special case of the discrete calculus of variations. Even when both endpoints of ? are fixed, this paper provides a new result. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Numerical resolution for a compressible two-phase flow model based on the theory of thermodynamically compatible systems

This paper is concerned with the numerical solution of the equations governing two-phase gas-solid mixture in the framework of thermodynamically compatible systems theory. The equations constitute a non-homogeneous system of nonlinear hyperbolic conservation laws. A total variation diminishing (TVD) slope limiter centre (SLIC) numerical scheme, based on the splitting approach, is presented and applied for the solution of the initial-boundary value problem for the equations. The model equations and the numerical methods are systematically assessed through a series of numerical test cases. Strong numerical evidence shows that the model and the methods are accurate, robust and conservative. The model correctly describes the formations of shocks and rarefactions in two-phase gas-solid flow.     

An explicit linear solution for the quadratic dynamic programming problem

For a given vectorx ₀, the sequence {x _t} which optimizes the sum of discounted rewardsr(x _t, x_t+1), wherer is a quadratic function, is shown to be generated by a linear decision rulex _t+1=Sx _t +R. Moreover, the coefficientsR,S are given by explicit formulas in terms of the coefficients of the reward functionr. A unique steady-state is shown to exist (except for a degenerate case), and its stability is discussed.     

Competition between humic acid and carbonates for rare earth elements complexation

The competitive binding of rare earth elements (REE) to humic acid (HA) and carbonates was studied experimentally at various pH and alkalinity values by combining ultrafiltration and inductively coupled plasma mass spectrometry techniques. The results show that the REE species occur as binary humate or carbonate complexes but not as ternary REE-carbonate-humate as previously proposed. The results also reveal the strong pH and alkalinity dependence of the competition as well as the existence of a systematic fractionation across the REE series. Specifically, carbonate complexation is at a maximum at pH 10 and increase with increasing alkalinity and with the atomic number of the REE (LuCO(3)>LaCO(3)). Modeling of the data using Model VI and recently published stability constants for complexation of REE by humic acid well reproduced the experimental data, confirming the ability of Model VI to accurately determine REE speciation in natural waters. This modeling also confirms the reliability of recently published stability constants. This work shed more light not only on the competition between carbonates and HA for REE complexation but also on the reliability of WHAM 6 and Model VI for calculating the speciation of REE with organic matter in alkaline organic-rich water.     

Exact Solution of the Time Fractional Variant Boussinesq-Burgers Equations

Applications of Mathematics - In the present article, we consider a nonlinear time fractional system of variant Boussinesq-Burgers equations. Using Lie group analysis, we derive the infinitesimal...     

Tailored coordination nanoparticles: assessing the magnetic single-domain critical size

Negatively charged nanocrystals of the magnetic coordination network CsNiCr(CN)(6) were prepared in water through a seed-mediated growth with a few atomic layers accuracy and final sizes tailored from 6 to 30 nm. A lower limit of the magnetic single-domain critical size was determined to be around 15 nm possessing a blocking temperature above 20 K.