Thermodynamic phases and mesonic fluctuations in a chiral nucleon-meson model

Studies of the QCD phase diagram must properly include nucleonic degrees of freedom and their thermodynamics in the range of baryon chemical potentials characteristic of nuclear matter. A useful framework for incorporating relevant nuclear physics constraints in this context is a chiral nucleon-meson effective Lagrangian. In the present paper, such a chiral nucleon-meson model is extended with systematic inclusion of mesonic fluctuations using the functional renormalization group approach. The resulting description of the nuclear liquid-gas phase transition shows a remarkable agreement with three-loop calculations based on in-medium chiral effective field theory. No signs of a chiral first-order phase transition and its critical endpoint are found in the region of applicability of the model, at least up to twice the density of normal nuclear matter and at temperatures T<100 MeV. Fluctuations close to the critical point of the first-order liquid-gas transition are also examined with a detailed study of the chiral susceptibility.Comment: 10 pages, 11 figures; references added, discussions enlarge

IFC model checking based on mvdXML 1.1

A significant barrier for successful use of BIM is the ability to efficiently and transparently agree on what data should be delivered by the many stakeholders of the supply chain and when. This requires additional agreements and specification work on top of existing standards like IFC. Ideally, these specifications are ready for automatic model checking to ensure the exchange of required BIM data. Based on the IDM/MVD methodology and the mvdXML 1.1 format developed by buildingSMART a web-based requirements management solution called BIM-Q and the mvdXML extension of the XBIM toolkit is discussed that demonstrates how BIM exchange requirements can be configured, managed and used for automatic model checking. All necessary steps are shown using an example from the STREAMER project, namely the Program of Requirements (PoR) and the early design of the room layout for hospitals. Besides presenting preliminary process implementation findings, grounded on data collected from various projects, persisting limitations for managing requirements and in particular for model checking based on mvdXML are discussed. An outlook of potential extensions and improvements of the different tools, mvdXML specification and the whole checking process is presented at the end

an experimental and theoretical study

MALDI mass spectrometry in combination with post-source decay (PSD) analysis is a fast and easy to apply method for peptide sequencing. In this study, the PSD technique was used to investigate the influence of the adaption of one, two, and three caesium cations to angiotensin II in the gas phase. The PSD spectra of caesium-aggregated angiotensin II show far less fragmentation in comparison to the protonated one. In the case of singly (doubly) Cs+ substituted angiotensin II, the PSD mass spectrum shows only fragments with one (two) Cs cation(s). These results are interpreted in terms of additional interactions of the caesium cation(s) with the peptide. In order to investigate this suggestion, the molecular structures were calculated with semi-empirical molecular dynamic (MD) simulations and further optimized at the quantum chemical level (BP86, SVP) of theory. On the one hand, secondary structures of Cs+ substituted angiotensin II are more compact than the structure of protonated angiotensin II, indicating electrostatic interactions of the Cs cations and the heterocyclic structures. Moreover, oxyphilic interactions of the cations with the oxygen atoms of the peptide backbone also contribute as further van-der-Waals interactions of the Cs+ substituted angiotensin II. These interactions are able to explain its higher stability due to reduced dissociation in comparison to the protonated angiotensin II. On the other hand, most MD simulations of doubly and triply Cs+ substituted angiotensin II show a formation of a [2 Cs] cluster, surrounded by the peptide molecule. The formation of this cluster would explain the lack of singly Cs+ substituted fragments in the PSD mass spectrum of doubly Cs+ substituted angiotensin II

Coherent control with shaped femtosecond laser pulses applied to ultracold molecules

We report on coherent control of excitation processes of translationally ultracold rubidium dimers in a magneto-optical trap by using shaped femtosecond laser pulses. Evolution strategies are applied in a feedback loop in order to optimize the photoexcitation of the Rb2 molecules, which subsequently undergo ionization or fragmentation. A superior performance of the resulting pulses compared to unshaped pulses of the same pulse energy is obtained by distributing the energy among specific spectral components. The demonstration of coherent control to ultracold ensembles opens a path to actively influence fundamental photo-induced processes in molecular quantum gases

From asymmetric nuclear matter to neutron stars: a functional renormalization group study

A previous study of nuclear matter in a chiral nucleon-meson model is extended to isospin-asymmetric matter. Fluctuations beyond mean-field approximation are treated in the framework of the functional renormalization group. The nuclear liquid-gas phase transition is investigated in detail as a function of the proton fraction in asymmetric matter. The equations of state at zero temperature of both symmetric nuclear matter and pure neutron matter are found to be in good agreement with realistic many-body computations. We also study the density dependence of the pion mass in the medium. The question of chiral symmetry restoration in neutron matter is addressed; we find a stabilization of the phase with spontaneously broken chiral symmetry once fluctuations are included. Finally, neutron star matter including beta equilibrium is discussed. The model satisfies the constraints imposed by the existence of two-solar-mass neutron stars.Comment: 12 pages, 11 figures, to appear in Phys. Rev. C, references added, figure 5 adde