Sökresultat

Filtyp

Din sökning på "*" gav 529814 sökträffar

Was the wage burden too heavy? - Settler farming, wages and the profitability of settler agriculture in colonial Malawi, c 1900-1960

The historical role of European farming in southern and central Africa is a delicate matter that has received a great deal of attention among scholars over the years. Going through this vast literature a striking consensus emerges: success or failure of European farming in southern Africa was to a large extent depending on their access and control over labour. These propositions have so far never

Optimal Wigner Cross-Spectrum Estimation

An expression for the mean-square error (MSE) optimal Wigner cross-spectrum estimator is derived within a wide class of estimators. Using this expression and a simplemodel we are able to construct a new estimator which turns out to be superior compared to standard estimators such as Thomson multitapers and Welch method on simulated data.

EFFECTS OF MANY-BODY INTERACTIONS IN EXTENDED X-RAY ABSORPTION FINE STRUCTURE SPECTROSCOPY (EXAFS)

Abstract : We present the first a priori derivation of a many-body theory for EXAFS with clearly defined approximations and with final expressions which are feasible for quantitative evaluations. We conclude that the conventional EXAFS expression should be complemented with a term that crudely is the main term, energy-shifted and scaled down by a factor of order 0.2-0.3. Further the f-factors depe

Theoretical study of electronic structure and optical properties of semiconductor nanostructures

In this thesis, the electronic structure and optical properties of semiconductor nanostructures are studied theoretically. Three types of nanostructures have been studied, silicon nanocrystals, free-standing III-V nanowires and free-standing GaAs/AlGaAs nanowire superlattices. The calculations have been carried out using an atomistic, empirical tight-binding approach. Silicon nanocrystals have at