The detailed characterization of proteins is a key step toward the understanding of biological processes on a molecular level. The determination of their three-dimensional structures, which is central to such a characterization, can resolve many mechanistic questions related to function. However, this static picture of biology on a molecular level ignores the dynamic nature of living processes, which is necessary to perform the molecular function. NMR spectroscopy is exquisitely suited to probe the dynamics of biomolecules, because of its capability to deliver atomic-resolution information about the conformational space that a protein samples and the rates at which different conformational states interconvert. This accessibility to both structural and kinetic aspects of protein flexibility has indeed made solution-state NMR spectroscopy an important technique for the understanding of protein function. An important part of biology, however, is actually not occurring in the solution state: exciting systems of outstanding biological relevance such as membrane proteins or amyloid fibrils are very difficult – if at all – amenable to solution-state NMR. Solid-state NMR has seen great progress in the past decade, and the structure and local dynamics of immobilized proteins can now also be studied at atomic resolution. While this promises exciting new insight into the function of these molecules, it remains to establish the methodology that will allow to extract information about dynamics on different time scales in an accurate and reliable manner. The project presented here aims at developing new methods and improving existing methods for the quantification of motional amplitudes and time scales in solid-state proteins. A particular emphasis will be made on solid-state NMR methods that address protein dynamics in the time window of microseconds to seconds. This is a particularly interesting time scale where the function of many proteins occurs. The understanding of intrinsic protein dynamics in this regime can therefore provide important insight into protein function. The methods developed in this project will allow to study a wide range of biophysical processes. They will be applied here to two membrane proteins: the potassium channel KcsA and the mitochondrial ADP/ATP transporter. The foreseen results will shed light onto the molecular mechanisms of trans-membrane transport in these two proteins.

Most of our current knowledge of protoplanetary disks originates from studies of the dust component (e.g. spectral energy distributions (SED), scattered light images, emission maps) despite the fact that dust comprises only 1% of the initial mass of the disk.In contrast, the dominant and essential gas component of a protoplanetary disk has proven more difficult to observe thus far. Combining the gas and dust information from protoplanetary disks is particularly important for understanding disk evolution. The Herschel Space Observatory, due to be launched in April of this year, will open an unexplored wavelength window in the far infrared regime, providing access to high-quality observations of the gas in disks. I have been invited to join the "GAS in Protoplanetary Systems" (GASPS) Open Time Key Project that will observe both continuum (dust) and line (gas), namely [CII], [OI] and water, emission for an unbiased sample of 240 young stars, spanning a large range of stellar masses as well as the entire duration of planet formation. This DiskEvol program will tackle the complex problem of combining consistently the constraints on the gas phase of a disk, provided by the Herschel observations, with our existing studies of the dust phase. Interpretation of gas observations is complicated by the large number of physical processes at play: chemistry, excitation and destruction of molecules, freeze-out onto the dust grains, to name a few. But, this is of particular importance as the dissipation of abundant gas remnant from star formation limits the timescale for giant planet formation, controls the dynamics of planetary bodies (of all sizes) during their formation and determines the final architecture of the planetary system. This proposal will rely on 1) the preparation of a database including observations and models for the GASPS project, resultant from ancillary data for GASPS in the millimetre regime and the generation of grids of radiative transfer models (SEDs and line fluxes), respectively. This initial work will allow 2) a detailed analysis of the GASPS program through a statistical comparison of the GASPS observations with the predictions from the grid of models. This global study, of the large sample of disks observed by GASPS, will be 3) extended and completed through finer detailed modelling of a selected sample of representative sources for which we will obtain a complete view of the dust structure and gas chemistry using simultaneous interpretation of continuum observations, resolved emission maps in low-level rotational lines of CO, in addition to follow-up observations with HIFI, a high-spectral resolution instrument on-board Herschel. DiskEvol will provide an unprecedented inventory of gas and dust in protoplanetary disks, transforming our understanding of disk evolution by addressing key questions on the timescales and main mechanisms of dust and gas evolution within disks. In addition, the long-lasting value of DiskEvol results is of exceptional importance in the era of ALMA and JWST.

With the detection of exo-planets, planet and star formation research has emerged as an exciting, competitive, and quickly evolving field at the forefront of current astrophysical research. Planet and star formation are closely related since the circumstellar disk through which the star accretes its mass is also the site of planet formation. Therefore, research focuses on circumstellar disks, their formation and evolution, and the formation of larger bodies inside the disk as building blocks for planets. It is the aim of this proposal to perform cutting-edge fundamental research in this exciting field addressing the question of our own origin. A key role in both star and planet formation is played by small dust particles mixed in the gas of the molecular cloud core where these processes take place. Not only are they important tracers of the dense regions where star formation starts, but they also contribute to the free charges, chemistry, and cooling of the gas. Moreover, they are the seeds for the planets to be formed in the accretion disk of the young star. Many aspects of planet formation process are still undetectable: we just begin to observe forming planets in disks, but not their building blocks, nor is there a clear picture why, e.g., meter-sized bodies in the disk do not just fall into the star. The proposed project is most timely: the applicant and a team of French and German scientists just have detected the so-called “coreshine” (published in Science). It is mid-infrared light scattered by dust grains in the inner cores of molecular clouds which are a factor 10 larger than the small grains dominating the low-density interstellar medium. Their presence indicates that dust grains can already grow in molecular cloud cores even before the star formation process has started. The work proposed here will focus on the exploration of the formation and evolution of this seed population of grown grains for further processing within the disk. In the project, Spitzer space telescope data will be analyzed to identify a sample of collapsing cores and disks with detectable coreshine, and additional data for all the sources from other telescopes will be gathered to complete the picture. The coreshine contains the information about the local variation in the grain sizes in the collapsing cores and disks, but to disentangle these properties remains a grand challenge problem of computational astrophysics. The applicant is an internationally recognized expert in exactly this field, which necessitates to perform a combination of 3D radiative transfer and automated fitting calculations. He will use his numerical code and experience to analyze the coreshine by computationally complex scattered light calculations coupled to an automated optimizer routine at the IPAG. Three-dimensional calculations are necessary since the coreshine appears in cloud cores and disks which are anisotropically illuminated by the interstellar radiation field. Automated fitting routine are required since the models for a collapsing core structure with an accretion disk located inside contain too many free parameters to search the parameter space “by hand”. This will add new competence to the excellent research done at IPAG in the fields of molecular cloud cores, accretion disks, dust growth, radiative transfer, and planet formation, providing the group with modern automated 3D radiative transfer techniques. In this quickly progressing field, efficient funding efforts are a necessary means to keep French science at the forefront of progress. The research proposed in this project correspondingly requests an efficient short-term funding to bring together the applicant's experience in automated 3D radiative transfer calculations and the disk/cloud core expertise at the IPAG host.