Candida albicans is a pathogenic fungus capable of switching its morphology between yeast-like cells and filamentous hyphae and can associate with bacteria to form mixed biofilms resistant to antibiotics. In these structures, the fungal milieu can play a protective function for bacteria as has recently been reported for C. albicans and a periodontal pathogen—Porphyromonas gingivalis. Our current study aimed to determine how this type of mutual microbe protection within the mixed biofilm affects the contacting host cells. To analyze C. albicans and P. gingivalis persistence and host infection, several models for host–biofilm interactions were developed, including microbial exposure to a representative monocyte cell line (THP1) and gingival fibroblasts isolated from periodontitis patients. For in vivo experiments, a mouse subcutaneous chamber model was utilized. The persistence of P. gingivalis cells was observed within mixed biofilm with C. albicans. This microbial co-existence influenced host immunity by attenuating macrophage and fibroblast responses. Cytokine and chemokine production decreased compared to pure bacterial infection. The fibroblasts isolated from patients with severe periodontitis were less susceptible to fungal colonization, indicating a modulation of the host environment by the dominating bacterial infection. The results obtained for the mouse model in which a sequential infection was initiated by the fungus showed that this host colonization induced a milder inflammation, leading to a significant reduction in mouse mortality. Moreover, high bacterial counts in animal organisms were noted on a longer time scale in the presence of C. albicans, suggesting the chronic nature of the dual-species infection.
Subtracting the Strutinsky shell corrections from the selfconsistent energies obtained within the Relativistic Mean Field Theory (RMFT) we have got estimates for the macroscopic part of the binding energies of 142 spherical even-even nuclei. By minimizing their root mean square deviations from the values obtained with the Lublin-Srasbourg Drop (LSD) model with respect to the nine RMFT parameters we have found the optimal set (NL4). The new parameters reproduce also the radii of these nuclei with an accuracy comparable with that obtained with the NL1 and NL3 sets. RMFT parametersThe Relativistic Mean Field Theory (RMFT) 1 , which is essentialy a Hartree-Fock like method based on the Dirac equation for nucleons and the Klein-Gordon equation for the : ρ, ω, σ mesons and photons, reproduces well the nuclear properties when its parameters (i.e.: masses of nucleons: m, mesons: m ρ , m ω , m σ and their coupling constants ρ ρ , ρ ω , ρ σ , ρ 2 , ρ 3 ) are fitted to the largest possible amount of nuclear data. Usually the masses and mean square radii of 8 magic nuclei were used to find the RMFT parameters and several sets were established for various regions and quantities as: masses, barriers or radii. We have chequed the quality of three sets: NL1 2 , NL2 3 , NL3 4 by comparing their macroscopic energies obtained by subtracting the Strutinsky shell correction, from the RMFT binding energies evaluated without pairing forces 5 with the Lublin-Strasbourg-Drop (LSD) energy 6 . The minimization of the root mean square of the differences of macroscopic energy allowed to find the new set of RMFT parameters NL4, which even if rather close to the NL3, as can be seen on the table below, results in a rms deviation that is more than 2 times better (7.17 MeV and 3.29 MeV respectively).
Self-consistent relativistic mean-field (RMF) calculations with the NL3 parameter set were performed for 171 spherical even-even nuclei with 16 ≤ A ≤ 224 at temperatures in the range 0 ≤ T ≤ 4 MeV. For this sample of nuclei single-particle level densities are determined by analyzing the data obtained for various temperatures. A new shell-correction method is used to evaluate shell effects at all temperatures. The single-particle level density is expressed as function of mass number A and relative isospin I and compared with previous estimates.In fission dynamics and the decay of compound nuclei 1 as well as in all kinds of transport theories, the proper knowledge of the nuclear single-particle level density is needed. The aim of the present paper is to determine this quantity using the RMF theory 2 with the NL3 3 set of parameters and a revised version of the Strutinsky shell correction method.4 The smooth part of nuclear energy is evaluated in our approach by an averaging in particle-number space while in the traditional Strutinsky method 5 the smoothing is performed in single-particle energy space. The advantage of the new approach consists in that the particle number is exactly conserved which was only the case on the average in the old Strutinsky method.Mass-number and isospin dependence of the single-particle level density obtained in the RMF approach with the NL3 parameters 3 were already discussed in Ref.6 . Using the Strutinsky shell-correction method 5 we had "removed" shell effects from the selfconsistent RMF energies in a similar way as done in Refs. 7,8,9 for the Gogny hamiltonian 10 and the RMF-NL3 model. 3 Estimates of the macroscopic binding energies (i.e. free of shell and pairing effects) obtained in such a way at zero temperature were used as a reference to calculate the change of the total energies with temperature. To simplify the calculations, the temperature dependence of the shell-correction energy was approximated in 6 by an analytical function 11 instead of explicitly evaluating the Strutinsky shell correction at finite temperatures.
A new set of relativistic mean-field theory (RMFT) parameters, NL4, ensuring a better description of the average nuclear energy as given by the new Lublin–Strasbourg mass formula, is used in a self-consistent description of 171 spherical even-even nuclei at temperatures 0≤T≤4 MeV. Single-particle level densities for this sample of nuclei are determined by analyzing the data obtained for various temperatures. The average dependence of the single-particle level density on mass number A and isospin is given and compared with previous estimates obtained using the RMFT-NL3, Thomas–Fermi and semiclassical Skyrme SkM* approaches.
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