ERC FUNDED PROJECTS

The rise of atmospheric O2 ~2,500 million years ago is one of the most profound transitions in Earth's history. Yet, despite its central role in shaping Earth's surface environment, the cause for the rise of O2 remains poorly understood. Tight coupling between the O2 cycle and the biogeochemical cycles of redox-active elements, such as C, Fe and S, implies radical changes in these cycles before, during and after the rise of O2. These changes, too, are incompletely understood, but have left valuable information encoded in the geological record. This information has been qualitatively interpreted, leaving many aspects of the rise of O2, including its causes and constraints on ocean chemistry before and after it, topics of ongoing research and debate. Here, I outline a research program to address this fundamental question in geochemical Earth systems evolution. The inherently interdisciplinary program uniquely integrates laboratory experiments, numerical models, geological observations, and geochemical analyses. Laboratory experiments and geological observations will constrain unknown parameters of the early biogeochemical cycles, and, in combination with field studies, will validate and refine the use of paleoenvironmental proxies. The insight gained will be used to develop detailed models of the coupled biogeochemical cycles, which will themselves be used to quantitatively understand the events surrounding the rise of O2, and to illuminate the dynamics of elemental cycles in the early oceans. This program is expected to yield novel, quantitative insight into these important events in Earth history and to have a major impact on our understanding of early ocean chemistry and the rise of O2. An ERC Starting Grant will enable me to use the excellent experimental and computational facilities at my disposal, to access the outstanding human resource at the Weizmann Institute of Science, and to address one of the major open questions in modern geochemistry.

1 472 690 €

Start date: 2013-09-01, End date: 2018-08-31

Despite its importance for human health and climate change organic aerosol (OA) remains one of the least understood aspects of atmospheric chemistry. We propose to develop an innovative new framework for the description of OA in chemical transport and climate models that will be able to overcome the challenges posed by the chemical complexity of OA while capturing its essential features. The objectives of ATMOPACS are: (i) The development of a new unified framework for the description of OA based on its two most important parameters: volatility and oxygen content. (ii) The development of measurement techniques for the volatility distribution and oxygen content distribution of OA. This will allow the experimental characterization of OA in this new “coordinate system”. (iii) The study of the major OA processes (partitioning, chemical aging, hygroscopicity, CCN formation, nucleation) in this new framework combining lab and field measurements. (iv) The development and evaluation of the next generation of regional and global CTMs using the above framework. (v) The quantification of the importance of the various sources and formation pathways of OA in Europe and the world, of the sensitivity of OA to emission control strategies, and its role in the direct and indirect effects of aerosols on climate. The proposed work involves a combination of laboratory measurements, field measurements including novel “atmospheric perturbation experiments”, OA model development, and modelling in urban, regional, and global scales. Therefore, it will span the system scales starting from the nanoscale to the global. The modelling tools that will be developed will be made available to all other research groups.

2 496 000 €

Start date: 2011-01-01, End date: 2015-12-31

Axon growth potential declines during development, contributing to the lack of effective regeneration in the adult central nervous system. What determines the intrinsic growth potential of neurites, and how such growth is regulated during development, disease and following injury is a fundamental question in neuroscience. Although multiple lines of evidence indicate that intrinsic growth capability is genetically encoded, its nature remains poorly defined. Neuronal remodeling of the Drosophila mushroom body offers a unique opportunity to study the mechanisms of various types of axon degeneration and growth. We have recently demonstrated that regrowth of axons following developmental pruning is not only distinct from initial outgrowth but also shares molecular similarities with regeneration following injury. In this proposal we combine state of the art tools from genomics, functional genetics and microscopy to perform a comprehensive study of the mechanisms underlying axon growth during development and following injury. First, we will combine genetic, biochemical and genomic studies to gain a mechanistic understanding of the developmental regrowth program. Next, we will perform extensive transcriptomic analyses and comparisons aimed at defining the genetic programs involved in initial axon growth, developmental regrowth, and regeneration following injury. Finally, we will harness the genetic power of Drosophila to perform a comprehensive functional analysis of genes and pathways, those previously known and new ones that we will discover, in various neurite growth paradigms. Importantly, these functional assays will be performed in the same organism, allowing us to use identical genetic mutations across our analyses. To this end, our identification of a new genetic program regulating developmental axon regrowth, together with emerging tools in genomics, places us in a unique position to gain a broad understanding of axon growth during development and following injury.

2 000 000 €

Start date: 2014-03-01, End date: 2019-02-28

The standard variational principles (VPs) are cornerstones of quantum mechanics, and one can hardly overestimate their usefulness as tools for generating approximations to the time-independent and time-dependent Schröodinger equations. The aim of the proposal is to study and apply a generalization of these, the bivariational principles (BIVPs), which arise naturally when one does not assume a priori that the system Hamiltonian is Hermitian. This unconventional approach may have transformative impact on development of ab initio methodology, both for electronic structure and dynamics. The first objective is to establish the mathematical foundation for the BIVPs. This opens up a whole new axis of method development for ab initio approaches. For instance, it is a largely ignored fact that the popular traditional coupled cluster (TCC) method can be neatly formulated with the BIVPs, and TCC is both polynomially scaling with the number of electrons and size-consistent. No “variational” method enjoys these properties simultaneously, indeed this seems to be incompatible with the standard VPs. Armed with the BIVPs, the project aims to develop new and understand existing ab initio methods. The second objective is thus a systematic multireference coupled cluster theory (MRCC) based on the BIVPs. This is in itself a novel approach that carries large potential benefits and impact. The third and last objective is an implementation of a new coupled-cluster type method where the orbitals are bivariational parameters. This gives a size-consistent hierarchy of approximations to multiconfiguration Hartree--Fock. The PI's broad contact with and background in scientific disciplines such as applied mathematics and nuclear physics in addition to quantum chemistry increases the feasibility of the project.

1 499 572 €

Start date: 2015-04-01, End date: 2020-03-31