92 research outputs found
Latest evidence for a late time vacuum -- geodesic CDM interaction
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. CDM, 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
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 CDM. The interaction is characterised by a dimensionless
coupling 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 CDM
evolution in the distant past, until a set redshift , below
which the interaction switches on and is the single sampled
parameter, with fixed at and respectively; a case where we allow this transition redshift to
vary along with ; a case in which the vacuum energy is zero for
and then begins to grow once the interaction switches on; and
the final case in which we bin 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 CDM.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
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
Strong lensing time delay constraints on dark energy: a forecast
Theoretical Physic
- …