Kobayashi geodesics in A_g

We consider Kobayashi geodesics in the moduli space of abelian varieties A_g that is, algebraic curves that are totally geodesic submanifolds for the Kobayashi metric. We show that Kobayashi geodesics can be characterized as those curves whose logarithmic tangent bundle splits as a subbundle of the logarithmic tangent bundle of A_g. Both Shimura curves and Teichmueller curves are examples of Kobayashi geodesics, but there are other examples. We show moreover that non-compact Kobayashi geodesics always map to the locus of real multiplication and that the Q-irreducibility of the induced variation of Hodge structures implies that they are defined over a number field.Comment: 2nd version, AMSLATeX, 20 pages. We fixed a gap in the proof of Lemma 3.1. The main theorems of our preprint are unchange

Europe's Brazil? How Ukraine could transform Europe's role in global food supply

Ukraine is an untapped asset. It presents opportunities both nationally and for Europe as an engine of foreign policy in a century troubled by climate change and resources scarcity. Its 32 million ha of arable could easily become 40 million ha which would add 25% of new cropland to the European Union - from 160 million to 200 million ha - making Europe the world’s largest agricultural producer. And 65% of Ukraine is Chernozem: the best soil in the world for the arable crops that are crucial to water-short economies in Africa, the Middle East and Asia and, moreover, mainstay of the global corporate food regime. 'Wheat is the currency of currencies'. Although most global breadbaskets are closed or constrained by climate change, Ukraine is an empty country endowed with fertile soil. Clever investment in AI-driven, post-human farming could create a new future: in any case, the minefields and war damage offer no alternative

A stable backbone for the fungi

Fungi are abundant in the biosphere. They have fascinated mankind as far as written history goes and have considerably influenced our culture. In biotechnology, cell biology, genetics, and life sciences in general fungi constitute relevant model organisms. Once the phylogenetic relationships of fungi are stably resolved individual results from fungal research can be combined into a holistic picture of biology. However, and despite recent progress, the backbone of the fungal phylogeny is not yet fully resolved. Especially the early evolutionary history of fungi and the order or below-order relationships within the ascomycetes remain uncertain. Here we present the first phylogenomic study for a eukaryotic kingdom that merges all publicly available fungal genomes and expressed sequence tags (EST) to build a data set comprising 128 genes and 146 taxa. The resulting tree provides a stable phylogenetic backbone for the fungi. Moreover, we present the first formal supertree based on 161 fungal taxa and 128 gene trees. The combined evidences from the trees support the deep-level stability of the fungal groups towards a comprehensive natural system of the fungi. They indicate that the classification of the fungi, especially their alliance with the Microsporidia, requires careful revision. Our analysis is also an inventory of present day sequence information for the fungi. It provides insights into which phylogenenetic conclusions can and which cannot be drawn from the current data and may serve as a guide to direct further sequencing initiatives. Together with a comprehensive animal phylogeny, we provide the second of three pillars to understand the evolution of the multicellular eukaryotic kingdoms, fungi, metazoa, and plants, in the past 1.6 billion years

Sicherung des Fachkräftepotenzials durch Nachqualifizierung

Das Erwerbspersonenpotenzial in Deutschland wird sich in den nächsten Jahren erheblich reduzieren. Bis 2030 wird aus demografischen Gründen und wegen einer steigenden Studierendenquote insbesondere die Zahl der Jugendlichen, die dem Ausbildungsmarkt potenziell zur Verfügung stehen, voraussichtlich um 20 Prozent zurückgehen (vgl. BIBB 2014; AGBB 2014). Dies könnte zu einem Mangel vor allem an beruflich qualifizierten Arbeitskräften führen (vgl. Helmrich/Zika 2010; Maier u.a. 2014). Bereits jetzt ist es in einigen Berufsgruppen nicht mehr uneingeschränkt möglich, vakante Stellen mit geeignetem Personal zu besetzen (vgl. BA 2013a). Der seit einigen Jahren zu beobachtende Rückgang der betrieblichen Ausbildungsquote (vgl. BIBB 2014; AGBB 2014, S.98 f.) wird dazu beitragen, dass Fachkräftelücken in weiteren Berufsgruppen entstehen

How do They Ride? Analysis of Cycling Biomechanics (“MODELO-Rad” Project)

For the planning and design of appropriate cycling facilities, aspects such as capacity, continuity, and objective safety are often subjects of research, but an understanding from the cyclist´s perspective, including physical and biomechanical characteristics, remains superficial. Findings related to cyclist behaviour have not yet been systematically applied and there is limited information on the relationship between cycling behaviour and characteristics of transport infrastructure. The “MODELO-Rad” project aims to understand and model cycling from the perspective of cyclists. Desired speed, riding strategy, and braking distance, among others, are important for understanding bike rides and provide insight on the behavioural characteristics of cyclists from a biomechanical perspective. This research suggests that a bike ride in an urban area can be divided into distinctive behavioural phases, characterized by degrees of power, speed, and cadence. To capture patterns of behaviour among cyclists, this study had participants ride along different routes on "SensorBikes,” which are equipped with sensor technology, to collect over 300 km of observations. The empirical analysis finds that cycling can be described as behavioural phases between stops (mostly between intersections): an acceleration phase, characterized by high power peaks; a route phase, which is subdivided into stages according to the route conditions (constant travel, deceleration and intermediate acceleration, uphill and downhill rolling); and an approach phase to the stopping point, usually at traffic lights or road junctions. Within these phases, results vary substantially between different cycling facilities and across different groups of cyclists. This description of cycling as a mechanical process can serve as a basis for the development of a micromodelling approach to cycling behaviour and can consequently be used to improve the planning of cycling networks and bike infrastructure