Structural Control Variables Research Articles

Convergence économique au sein de l’espace ouest-africain: L’intégration économique régionale à l’épreuve des faits

Dans cet article nous proposons d'abord une discussion à la lumière des travaux récents sur la convergence économique ou non des pays ouest-africains qui sont dans le processus de régionalisation des échanges depuis 1975. Nous examinons, ensuite, les déterminants de la convergence en prenant appui sur une analyse économétrique spatiale de tous ces États sur la période 1990-2021. Les résultats obtenus font ressortir que les économies sont globalement et fortement divergentes ; les convergences absolue et conditionnelle n'étant pas réalisées. Mais trois clubs de convergence ont été décelés, avec le Sénégal qui fait bande à part. Le taux d'investissement, les dépenses publiques, le taux d'inflation, la parité du pouvoir d'achat, le taux d'ouverture commerciale, le taux de scolarisation et le taux de croissance démographique, variables structurelles de contrôle, ont joué un rôle important dans l'appréciation de la vitesse et du niveau de divergence des économies ouest-africaines. Ceci a mis en évidence les écarts des revenus par tête, le retard dans les mécanismes intégrateurs et les effets des chocs auxquels ces économies sont soumises.

Human Capital and the Adoption of Information and Communications Technologies: Evidence from Investment Climate Survey of Pakistan

This paper studies the impact of human capital on the adoption and diffusion of Information and Communications Technologies (ICT) in the Pakistani firms using the World Bank Enterprise Survey 2002-07. The paper considers various indicators of human capital and measures of ICT adoption and diffusion. On-the-job training, manager's level of qualification and production workers' level of education are found to positively determine the use of emails, website and other means of communication in a firm. The results are robust to the inclusion of geographical, sectoral and structural control variables. Firm size, sales and workers' compensation are also positively associated with the use of ICT. The findings show the importance of accumulation and development of human capital in the productivity growth in the era of skill-biased technical change. A concerted national effort for the enhancement of the workforce's computing skills is therefore a must if a developing economy such as Pakistan is to improve its competitiveness.

Quantum control by means of Hamiltonian structure manipulation

A traditional quantum optimal control experiment begins with a specific physical system and seeks an optimal time-dependent field to steer the evolution towards a target observable value. In a more general framework, the Hamiltonian structure may also be manipulated when the material or molecular 'stockroom' is accessible as a part of the controls. The current work takes a step in this direction by considering the converse of the normal perspective to now start with a specific fixed field and employ the system's time-independent Hamiltonian structure as the control to identify an optimal form. The Hamiltonian structure control variables are taken as the system energies and transition dipole matrix elements. An analysis is presented of the Hamiltonian structure control landscape, defined by the observable as a function of the Hamiltonian structure. A proof of system controllability is provided, showing the existence of a Hamiltonian structure that yields an arbitrary unitary transformation when working with virtually any field. The landscape analysis shows that there are no suboptimal traps (i.e., local extrema) for controllable quantum systems when unconstrained structural controls are utilized to optimize a state-to-state transition probability. This analysis is corroborated by numerical simulations on model multilevel systems. The search effort to reach the top of the Hamiltonian structure landscape is found to be nearly invariant to system dimension. A control mechanism analysis is performed, showing a wide variety of behavior for different systems at the top of the Hamiltonian structure landscape. It is also shown that reducing the number of available Hamiltonian structure controls, thus constraining the system, does not always prevent reaching the landscape top. The results from this work lay a foundation for considering the laboratory implementation of optimal Hamiltonian structure manipulation for seeking the best control performance, especially with limited electromagnetic resources.