192 research outputs found
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
Generic Services for the Support of Evolving Building Model Data
Many problems related to data integration in AEC can be better tackled by an approach that takes into account the heterogeneity of tasks, models and applications but does not require continuous consistency of the evolving design data, at each data management operation. Such an approach must incorporate adequate services that can facilitate reintegration of concurrently modified data at reasonably selected coordination points. In this paper we present a set of methods which, used in combination, can achieve that goal. After a description of the principal envisaged cooperative work scenario each of these methods is discussed in detail and current observations drawn from their software realisation are given. Whilst the suggested approach is valid for any EXPRESS-based data model, the practical focus of work has been on facilitating IFC-driven integration
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