African peasants on the move: turmoil between global dynamics, migration and food insecurity

This issue presents some of the publications resulting from the research project “African societies facing global dynamics: Turbulences between external intervention, migration, and food insecurity” [Dynamics]1. The underlying idea was to investigate contemporary global dynamics faced by African societies, how they interact with internal processes of change and these societies’ responses to these pressures. The contributions address the key issues raised in the Dynamics research project in different ways. They focus on an analysis of migration (internal as well as international), agricultural transformation and food (in)security in different societies and locations. They also explore the links between them and their interrelations with global dynamics. The work was based on case studies conducted in Guinea-Bissau, São Tomé and Príncipe (STP), Cape Verde and Senegal. An additional contribution from Mozambique was also included as it addressed the central issues of the project. Although this research project in itself can only address a few aspects of this complex set of interactions and highlight some of the key issues at play in specific case studies, the project is part of a long-term investigation about the dynamics of change in African agrarian societies which contemplates a wider range of issues.info:eu-repo/semantics/publishedVersio

Enantioselective synthesis of (S)-2-hydroxypropanone derivatives by benzoylformate decarboxylase catalyzed C-C-bond formation

Chiral 2-hydroxypropanone derivatives 5a-v, 8a-d, and 10a, b were formed by benzoylformate decarboxylase (BFD) catalyzed C-C bond formation. A donor aldehyde and acetaldehyde as an acceptor were carboligated in aqueous buffer solution with remarkable ease in high chemical yield and good to high optical purity. The substrate range of this thiamin diphosphate dependent enzyme was examined to employ this benzoin condensation type reaction in stereoselective synthesis. The observed dependence of the enantiomeric excess on the substitution pattern could be exploited to design substrates resulting in high selectivity Best substrates with regard to optical purity were meta-substituted benzaldehyde derivatives. To enable a general and convenient applicability of the BFD-catalyzed C-C bond formation, analytical batch experiments were scaled up to give (S)-2-hydroxy ketones in good to high yields on a preparative scale. Further, the solubility of some of the organic substrates in aqueous solution was increased by the use of cyclodextrin or buffer/DMSO mixtures

Automated segmentation of the locus coeruleus from neuromelanin-sensitive 3t MRI using deep convolutional neural networks

The locus coeruleus (LC) is a small brain structure in the brainstem that may play an important role in the pathogenesis of Alzheimer’s Disease (AD) and Parkinson’s Disease (PD). The majority of studies to date have relied on using manual segmentation methods to segment the LC, which is time consuming and leads to substantial interindividual variability across raters. Automated segmentation approaches might be less error-prone leading to a higher consistency in Magnetic Resonance Imaging (MRI) contrast assessments of the LC across scans and studies. The objective of this study was to investigate whether a convolutional neural network (CNN)-based automated segmentation method allows for reliably delineating the LC in in vivo MR images. The obtained results indicate performance superior to the inter-rater agreement, i.e. approximately 70% Dice similarity coefficient (DSC)