ERC FUNDED PROJECTS

The goal of this project is to investigate two conjectures in arithmetic geometry pertaining to the geometry of projective varieties over finite and number fields. These two conjectures, formulated by Tate and Grothendieck in the 1960s, predict which cohomology classes are chern classes of line bundles. They both form an arithmetic counterpart of a theorem of Lefschetz, proved in the 1940s, which itself is the only known case of the Hodge conjecture. These two long-standing conjectures are one of the aspects of a more general web of questions regarding the topology of algebraic varieties which have been emphasized by Grothendieck and have since had a central role in modern arithmetic geometry. Special cases of these conjectures, appearing for instance in the work of Tate, Deligne, Faltings, Schneider-Lang, Masser-Wüstholz, have all had important consequences. My goal is to investigate different lines of attack towards these conjectures, building on recent work on myself and Jean-Benoît Bost on related problems. The two main directions of the proposal are as follows. Over finite fields, the Tate conjecture is related to finiteness results for certain cohomological objects. I want to understand how to relate these to hidden boundedness properties of algebraic varieties that have appeared in my recent geometric proof of the Tate conjecture for K3 surfaces. The existence and relevance of a theory of Donaldson invariants for moduli spaces of twisted sheaves over finite fields seems to be a promising and novel direction. Over number fields, I want to combine the geometric insight above with algebraization techniques developed by Bost. In a joint project, we want to investigate how these can be used to first understand geometrically major results in transcendence theory and then attack the Grothendieck period conjecture for divisors via a number-theoretic and complex-analytic understanding of universal vector extensions of abelian schemes over curves.

1 222 329 €

Start date: 2016-12-01, End date: 2021-11-30

Early life immune balance is essential for survival and establishment of healthy immunity in later life. We aim to define how age-dependent regulation of dendritic cell (DC) development contributes to this crucial immune balance. DCs are versatile controllers of immunity that in neonates are qualitatively distinct from adults. Why such age-dependent differences exist is unclear but newborn DCs are considered underdeveloped and functionally immature. Using ontogenetic tracing of conventional DC precursors, I have found a previously unappreciated developmental heterogeneity of DCs that is particularly prominent in young mice. Preliminary data indicate that distinct waves of DC poiesis contribute to the functional differences between neonatal and adult DCs. I hypothesize that the neonatal DC compartment is not immature but rather that DC poiesis is developmentally regulated to create essential age-dependent immune balance. Further, I have identified a unique situation in early life to address a fundamental biological question, namely to what extent cellular function is pre-programmed by developmental origin (nature) versus environmental factors (nurture). In this proposal, we will first use novel models to fate map the origin of the DC compartment with age. We will then define to what extent cellular origin determines age-dependent functions of DCs in immunity. Using innovative comparative gene expression profiling and integrative epigenomic analysis the cell intrinsic mechanisms regulating the age-dependent functions of DCs will be characterized. Because environmental factors in utero and after birth critically influence immune balance, we will finally define the impact of maternal infection and metabolic disease, as well as early microbial encounter on DC poiesis. Characterizing how developmentally regulated DC poiesis shapes the unique features of early life immunity will provide novel insights into immune development that are vital to advance vaccine strategies.

1 500 000 €

Start date: 2017-06-01, End date: 2022-05-31

Biofilms are antibiotic-resistant, sessile bacterial communities that occupy most moist surfaces on Earth and represent a major mode of bacterial life. Another common feature of bacterial life is exposure to viral parasites (termed phages), which are a dominant force in bacterial population control throughout nature. Surprisingly, almost nothing is known about the interactions between biofilm-dwelling bacteria and phages. This proposal is designed to fill this gap using a combination of novel methodology, experimental systems, and mathematical modeling. We have recently developed a new microscopic imaging technique that allows us to image and track all individual cells and their gene expression inside biofilms. First, we will use this technique for tracking the population dynamics of bacteria and phages within biofilms at single cell resolution. By genetically manipulating bacterial hosts and their phages, and by varying environmental conditions, we will investigate the fundamental biological and physical determinants of phage spread within biofilm communities. Second, we will study how biofilms respond to phage attack on both intra-generational and evolutionary time scales, focusing in particular on proximate response mechanisms and the population dynamics of phage-resistant and phage-susceptible cells as a function of biofilm spatial structure. Lastly, we will combine our novel insights to engineer phages that manipulate the composition of biofilm communities, either by subtraction of particular bacterial species or by addition of novel phenotypes to existing biofilm community members. Altogether, the proposed research promises to uncover the major mechanistic and evolutionary elements of biofilm-phage interactions. This combined work will greatly enrich our knowledge of microbial ecology and motivate novel strategies for bacterial biofilm control, an increasingly urgent priority in light of widespread antibiotic resistance.

1 494 963 €

Start date: 2017-01-01, End date: 2021-12-31

Coherence of law is created in the writings of legal scholars who systematize rules and principles of law. Their pursuit of coherence is vital for the effectiveness of legal systems. However, coherence of law has almost not been analysed in a systematic, empirical way. The project will therefore develop a methodology that will address coherence across forms (‘sources’) of law (legislation, legal scholarship, case law, customs), across themes (e.g. criminal law and contracts) and across authors, and which will additionally encompass interaction with societal demand and contextual factors. The methodology will be ground-breaking because it will disentangle the concept of coherence into measurable modes of interconnectedness, weighing them together so as to assess (in)coherence at the level of the legal system. This methodology will constitute a stepping stone for a new field of dynamic coherence of law created through legal scholarship that will ultimately improve the quality of law. It will be founded on academic writings on law from the early modern period (ca. 1500 - ca. 1800) that concern the theme of collateral rights, that is, those rights facilitating expropriation of the assets of debtors in case of their default. Indications are that the impact of rules on collateral rights hinged on coherence as established in legal writings, and that in the period mentioned legal coherence for this theme was increasing. Coherence in development will be traced in the interpretations of legal scholars following on from interactions between scholarly writings, local law (bylaws, judgments) and commercial practice (contracts). Connections of rules and principles found will be presented in frames of analysis that cluster them along variables of context, time and source of law. The combination of legal analysis with a broad scope of coherence (cross-source, context-driven) will build bridges across gaps now existing between the different disciplines that study law.

1 495 625 €

Start date: 2017-01-01, End date: 2021-12-31