Resonant multiple Andreev reflections in mesoscopic superconducting junctions

We investigate the properties of subharmonic gap structure (SGS) in superconducting quantum contacts with normal-electron resonances. We find two distinct new features of the SGS in resonant junctions which distinguish them from non-resonant point contacts: (i) The odd-order structures on the current-voltage characteristics of resonant junctions are strongly enhanced and have pronounced peaks, while the even-order structures are suppressed, in the case of a normal electron resonance being close to the Fermi level. (ii) Tremendous current peaks develop at $eV=\pm 2E_0$ where $E_0$ indicates a distance of the resonance to the Fermi level. These properties are determined by the effect of narrowing of the resonance during multiple Andreev reflections and by overlap of electron and hole resonances.Comment: 13 pages, 10 figure

Assessing the adoption potential of agroforestry practices in sub-Saharan Africa

This paper reviews the application of various types of on-farm trials and methods for collecting and analysing data needed to assess the adoption potential of agroforestry practices. The review is based on farmers' and researchers' experiences in seven case studies in three countries of sub-Saharan Africa assessing the biophysical performance, profitability and acceptability of agroforestry practices. Assessments of adoption potential are key elements of a participatory, farmer-centered model of research and development. They improve the efficiency of the technology development and dissemination process, help document the progress made in disseminating new practices, demonstrate the impact of investing in technology development, provide farmer feedback for improving research and extension programmes, and help to identify the policy and other factors contributing to successful technology development programmes as well as the constraints limiting the achievements

Chemical Gradients in Cu(In,Ga)(S,Se)2 Thin-Film Solar Cells: Results of the GRACIS Project

The German joint research project “Chemical Gradients in Cu(In,Ga)(S,Se)2” (GRACIS) is an initiative to gain a better physical understanding concerning the formation of chemical gradients in the Cu(In,Ga)(S,Se)2 (CIGS) absorber layers and at the CIGS/buffer interface. This article presents the current status of the GRACIS project after three years of execution with results concerning phase formation during chalcogenization and coevaporation processes, influence of Ga grading on structural and electrical parameters as well as on inhomogeneities on the μm scale of CIGS. Special features of the CIGS/Zn(O,S) buffer interface are discussed and compared to CIGS solar cells with CdS buffer. In addition, our experimental results are supported by 3D simulations and calculations using screened-exchanged hybrid density functional theory

Subcellular Recruitment of Fibrillarin to Nucleoplasmic Proteasomes: Implications for Processing of a Nucleolar Autoantigen

A prerequisite for proteins to interact in a cell is that they are present in the same intracellular compartment. Although it is generally accepted that proteasomes occur in both, the cytoplasm and the nucleus, research has been focusing on cytoplasmic protein breakdown and antigen processing, respectively. Thus, little is known on the functional organization of the proteasome in the nucleus. Here we report that within the nucleus 20S and 26S proteasomes occur throughout the nucleoplasm and partially colocalize with splicing factor–containing speckles. Because proteasomes are absent from the nucleolus, a recruitment system was used to analyze the molecular fate of nucleolar protein fibrillarin: Subtoxic concentrations of mercuric chloride (HgCl(2)) induce subcellular redistribution of fibrillarin and substantial colocalization (33%) with nucleoplasmic proteasomes in different cell lines and in primary cells isolated from mercury-treated mice. Accumulation of fibrillarin and fibrillarin-ubiquitin conjugates in lactacystin-treated cells suggests that proteasome-dependent processing of this autoantigen occurs upon mercury induction. The latter observation might constitute the cell biological basis of autoimmune responses that specifically target fibrillarin in mercury-mouse models and scleroderma