92 research outputs found

    Latest evidence for a late time vacuum -- geodesic CDM interaction

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    We perform a reconstruction of the coupling function between vacuum energy and geodesic cold dark matter using the latest observational data. We bin the interaction in seventeen redshift bins but use a correlation prior to prevent rapid, unphysical oscillations in the coupling function. This prior also serves to eliminate any dependence of the reconstruction on the binning method. We use two different forms of the correlation prior, finding that both give similar results for the reconstruction of the dark matter -- dark energy interaction. Calculating the Bayes factor for each case, we find no meaningful evidence for deviation from the null interacting case, i.e. Λ\LambdaCDM, in our reconstruction.Comment: 14 pages, 7 figures. Version 2 matches published version in Physics of the Dark Universe (Figure 2 updated to better show H0 and sigma 8 tensions, additional discussion of results added in section 4.1

    Constraints on the interacting vacuum -- geodesic CDM scenario

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    We investigate an interacting dark sector scenario in which the vacuum energy is free to interact with cold dark matter (CDM), which itself is assumed to cluster under the sole action of gravity, i.e. it is in free fall (geodesic), as in Λ\LambdaCDM. The interaction is characterised by a dimensionless coupling qVq_{\rm V} that we constrain using cosmic microwave background data from the Planck 2015 data release, along with baryon acoustic oscillation, redshift space distortion and Type Ia supernova measurements. We present the full linear perturbation theory of this interacting scenario and use MCMC sampling to study five different cases: two cases in which we have Λ\LambdaCDM evolution in the distant past, until a set redshift ztransz_{\rm trans}, below which the interaction switches on and qVq_{\rm V} is the single sampled parameter, with ztransz_{\rm trans} fixed at ztrans=3000z_{\rm trans}=3000 and ztrans=0.9z_{\rm trans}=0.9 respectively; a case where we allow this transition redshift to vary along with qVq_{\rm V}; a case in which the vacuum energy is zero for z>ztransz>z_{\rm trans} and then begins to grow once the interaction switches on; and the final case in which we bin qV(z)q_{\rm V}(z) in four redshift bins to investigate the possibility of a dynamical interaction, reconstructing the redshift evolution of the function using Gaussian processes. We find that, in all cases where the high redshift evolution is not modified, the results are compatible with a vanishing coupling, thus finding no significant deviation from Λ\LambdaCDM.Comment: 17 pages, 14 figures. Version 2 aligns with the published MNRAS article (some model comparison discussion added with respect to version 1

    Biomolecular, histological, clinical, and radiological analyses of dental implant bone sites prepared using magnetic mallet technology: A pilot study in animals

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    Background. A new instrumentation exploiting magneto-dynamic technology (mallet) proposed for implant site preparation was investigated. Methods. In the tibias of three minipigs, two sites were prepared by mallet and two by drill technique. Primary stability (ISQ) was detected after implant positioning (T0) and at 14 days (T14). X-rays and computed tomography were performed. At T14, bone samples were utilized for histological and biomolecular analyses. Results. In mallet sites, histological evaluations evidenced a significant increase in the newly formed bone, osteoblast number, and a smaller quantity of fibrous tissue. These results agree with the significant BMP-4 augmentation and the positive trend in other osteogenic factors (biological and radiological investigations). Major, albeit IL-10-controlled, inflammation was present. For both techniques, at T14 a significant ISQ increase was evidenced, but no significant difference was observed at T0 and T14 between the mallet and drill techniques. In mallet sites, lateral bone condensation was observed on computed tomography. Conclusions. Using biological, histological, clinical, and radiological analyses, this study first shows that the mallet technique is effective for implant site preparation. Based on its ability to cause osseocondensation and improve newly formed bone, mallet technology should be chosen in all clinical cases of poor bone quality
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