Electron Wave Filters from Inverse Scattering Theory

Semiconductor heterostructures with prescribed energy dependence of the transmittance can be designed by combining: {\em a)} Pad\'e approximant reconstruction of the S-matrix; {\em b)} inverse scattering theory for Schro\"dinger's equation; {\em c)} a unitary transformation which takes into account the variable mass effects. The resultant continuous concentration profile can be digitized into an easily realizable rectangular-wells structure. For illustration, we give the specifications of a 2 narrow band-pass 12 layer $Al_cGa_{1-c}As$ filter with the high energy peak more than {\em twice narrower} than the other.Comment: 4 pages, Revtex with one eps figur

RESEARCHES ON SOIL CONTAMINATION WITH HEAVY METALS AND THEIR REMANENCE IN VEGETABLES

 The paper presents the results of experimental researches on soil contamination with heavy metals (copper, lead, zinc) in different concentration each (c1=1.5 %; c2=3.0 %; c3=4.5 %; c4=6.0 %). The contaminated soil was placed in pots, where spinach and radish seeds were planted. The vegetables were grown in a greenhouse until the end of the vegetation period, afterwards being harvested and the remanence of each heavy metal for each concentration was determined for each plant. The results obtained were compared with the blank sample where the soil was not contaminated.        The purpose of the study was to identify the levels of heavy metals (Cu, Zn and Pb) transfer/absorption from the soil into spinach leaves respectively radish roots

Renaturing cities: from utopias to contested realities and futures

Renaturing urban environments is a transformative pathway for urban sustainability that can be leveraged for collaborative research and planning to reverse long trends of ecosystem degradation. People-nature connections need to be reinforced to enable the successful uptake and upscale of urban renaturing practices. Improving people's understanding, perception, and emotions towards nature is therefore key. In this paper, we discuss how human knowledge and values of nature can be enabled through urban renaturing. Besides, we discuss the required transitions in urban planning processes to support urban renaturing practices