Given stationary time series data, we study the problem of finding the best linear combination of a set of lag window spectral density estimators with respect to the mean squared risk. We present an aggregation procedure and prove a sharp oracle inequality for its risk. We also provide...

Two-dimensional (2D) photonic band gaps (PBG) structure fabricated from anisotropic dielectric is studied by solving Maxwell’s equations with use of plane-wave expansion method. Numerical simulations show that absolute photonic band gaps can be substantially improved in two dimensional square...

In this paper we report an experimental investigation on the dynamics of the azimuthal director reorientation at a nematic-solid interface. Three qualitatively different kinds of substrates have been investigated: I) intrinsically anisotropic SiO-substrates (60°-evaporation), II) isotropic...

The European Union established a long-term process for the development and implementation of comprehensive measures in its regional and cohesion policies. The involved structural instruments became drives for sustainable socio-economic development. The structural funds allocated to Romania for...

We introduce a new ‘supply-push’ instrument for foreign aid, to be used together with an instrumental variable estimator that filters out unobserved common factors. We use this instrument to study the effects of aid on macroeconomic ratios, and especially the ratios of consumption,...

Stimulating economic growth is one of the key issues of economic sciences. The European Union has developed several policies and has allocated a considerable budget to reduce economic disparities among its members. The states that joined the EU in 2004 and 2007 undertake extensive efforts to...