Frankfurt Institute for Advanced Studies

About: Frankfurt Institute for Advanced Studies is a facility organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Baryon & Quark–gluon plasma. The organization has 798 authors who have published 2733 publications receiving 82799 citations. The organization is also known as: FIAS.

Fluctuations in the canonical ensemble

Abstract: The particle number and energy fluctuations in a system of charged particles are studied in the canonical ensemble for nonzero net values of the conserved charge. In the thermodynamic limit, the fluctuations in the canonical ensemble differ from those in the grand canonical ensemble. A system with several species of particles is considered. We calculate the quantum statistical effects that can be taken into account for the canonical ensemble fluctuations in the infinite-volume limit. The fluctuations of the particle numbers in the pion-nucleon gas are considered in the canonical ensemble as an example of the system with two conserved charges---baryonic number and electric charge.

Ab initio study of alanine polypeptide chain twisting.

Abstract: We have investigated the potential energy surfaces for alanine chains consisting of three and six amino acids. For these molecules we have calculated potential energy surfaces as a function of the Ramachandran angles $\ensuremath{\varphi}$ and $\ensuremath{\psi}$, which are widely used for the characterization of the polypeptide chains. These particular degrees of freedom are essential for the characterization of the proteins folding process. Calculations have been carried out within the ab initio theoretical framework based on the density functional theory and accounting for all the electrons in the system. We have determined stable conformations and calculated the energy barriers for transitions between them. Using a thermodynamic approach, we have estimated the times of characteristic transitions between these conformations. The results of our calculations have been compared with those obtained by other theoretical methods and with the available experimental data extracted from the Protein Data Base. This comparison demonstrates a reasonable correspondence of the most prominent minima on the calculated potential energy surfaces to the experimentally measured angles $\ensuremath{\varphi}$ and $\ensuremath{\psi}$ for alanine chains appearing in native proteins. We have also investigated the influence of the secondary structure of polypeptide chains on the formation of the potential energy landscape. This analysis has been performed for the sheet and the helix conformations of chains of six amino acids.

Localized vs. synchronized exports across a highly renewable pan‐European transmission network

Abstract: A future, highly renewable electricity system will be largely based on fluctuating renewables. The integration of wind and solar photovoltaics presents a major challenge. Transmission can be used to lower the need for complementary generation, which we term backup in this article. Generation data based on historical weather data, combined with real load data, determine hourly mismatch timeseries for all European countries, connected by physical power flows. Two localized export schemes determining the power flows are discussed, which export only renewable excess power, but no backup power, and are compared to a synchronized export scheme, which exports renewable excess power and also backup power. Compared to no or very limited power transmission, unconstrained power flows across a highly renewable pan‐European electricity network significantly reduce the overall amount of required annual backup energy, but not necessarily the required backup capacities. The reduction of the backup capacities turns out to be sensitive to the choice of export scheme. Results suggest that the synchronized export of local backup power to other countries is important to significantly save on installed backup capacities.