Functional renormalization group approach to neutron matter

The chiral nucleon-meson model, previously applied to systems with equal number of neutrons and protons, is extended to asymmetric nuclear matter. Fluctuations are included in the framework of the functional renormalization group. The equation of state for pure neutron matter is studied and compared to recent advanced many-body calculations. The chiral condensate in neutron matter is computed as a function of baryon density. It is found that, once fluctuations are incorporated, the chiral restoration transition for pure neutron matter is shifted to high densities, much beyond three times the density of normal nuclear matter.Comment: 5 pages, 4 figures, to appear in Phys. Lett.

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

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

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

A Methodology for the Digitalization of the Residential Building Renovation Process through OpenBIM-Based Workflows

The European building industry is facing a strong increase in renovation processes, which are still non-cost-effective, involve unproperly coordinated stakeholders, are disturbing for the occupants, and cause important inefficiencies in the overall renovation process. In this context, digitalization and Building Information Modelling (BIM), as an enabler, is the key solution that may drive renovation interventions to ensure a more successful and leaner process, aiding the whole value chain of actors to achieve its full potential. This research describes the OpenBIM methodology applied in order to transform the implicit knowledge from the stakeholders involved in the building renovation process, not structured enough for automation, into an OpenBIM digital process based on the BIM standards. The outcomes of this research are the OpenBIM ready workflows that represent the renovation process and information requirements according to the involvement of different stakeholders rooted in the analysis of barriers, requirements, and needs. Those workflows are the basis for the future development of specific products and tools for boosting digitalization and interoperability in the renovation process.This work has been developed within the project BIM4Ren. The project has received funding from the European Union’s Horizon H2020 research and innovation program under Grant Agreement No 820773

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

Photoassociation and coherent transient dynamics in the interaction of ultracold rubidium atoms with shaped femtosecond pulses - I. Experiment

We experimentally investigate various processes present in the photoassociative interaction of an ultracold atomic sample with shaped femtosecond laser pulses. We demonstrate the photoassociation of pairs of rubidium atoms into electronically excited, bound molecular states using spectrally cut femtosecond laser pulses tuned below the rubidium D1 or D2 asymptote. Time-resolved pump-probe spectra reveal coherent oscillations of the molecular formation rate, which are due to coherent transient dynamics in the electronic excitation. The oscillation frequency corresponds to the detun-ing of the spectral cut position to the asymptotic transition frequency of the rubidium D1 or D2 lines, respectively. Measurements of the molecular photoassociation signal as a function of the pulse energy reveal a non-linear dependence and indicate a non-perturbative excitation process. Chirping the association laser pulse allowed us to change the phase of the coherent transients. Furthermore, a signature for molecules in the electronic ground state is found, which is attributed to molecule formation by femtosecond photoassociation followed by spontaneous decay. In a subsequent article [A. Merli et al., submitted] quantum mechanical calculations are presented, which compare well with the experimental data and reveal further details about the observed coherent transient dynamics