Accretion Disk Luminosity for Black Holes Surrounded by Dark Matter with Anisotropic Pressure

We investigate the luminosity of the accretion disk of a static black hole surrounded by dark matter with anisotropic pressure. We calculate all basic orbital parameters of test particles in the accretion disk, such as angular velocity, angular momentum, energy, and radius of the innermost circular stable orbit as functions of the dark matter density, radial pressure, and anisotropic parameter, which establishes the relationship between the radial and tangential pressures. We show that the presence of dark matter with anisotropic pressure makes a noticeable difference in the geometry around a Schwarzschild black hole, affecting the radiative flux, differential luminosity, and spectral luminosity of the accretion disk

The Impact of Repeated Abutment Changes on Peri-implant Tissue Stability: Five-year Post-loading Results From a Multicentre Randomised Controlled Trial

PURPOSE. To evaluate the impact of at least three abutment disconnections on hard and soft tissues around conventionally loaded implants versus definitive immediately non-oc-clusally loaded abutments in implants. A secondary aim was to evaluate whether the presence of less than 2 mm of keratinised mucosa is associated with increased soft tissue recession and/or peri-implant marginal bone loss. MATERIALS AND METHODS. Eighty patients requiring one single crown or one fixed partial prosthesis supported by a maximum of three implants were randomised, after implant placement at greater than 35 Ncm, according to a parallel-group design to receive either definitive immediately loaded abutments (definitive abutment or immediate loading group) or transmucosal abutments which were loaded after a delay of 3 months and removed at least three times. Patients were treated in four centres, and each patient contributed to the study with only one prosthesis, which was followed up for 5 years after initial loading. Outcome measures were: prosthesis failures, implant failures, complica-tions, pink aesthetic score (PES), buccal recessions, patient satisfaction, peri-implant marginal bone-level changes and height of the keratinised mucosa. RESULTS. Forty patients were randomly allocated to each group according to a paral-lel-group design. Seven patients from the definitive abutment group versus six from the repeated disconnection group dropped out or died. No patient from the definitive group had implant failures versus three patients who lost five implants in the repeated disconnection group (difference = 9.1%; CI95%:-0.7% to 18.9% to; P = 0.227). Nine patients from the repeated disconnection group lost or had to have their prosthesis remade (four provisional and five definitive prostheses) versus one provisional prosthesis failure in the definitive abutment group; this difference was statistically significant (difference = 23.5%; CI95%: 7.6% to 39.4%; P = 0.017), but was due to the erroneous use of non-indexed abutments in indexed implants in patients from the repeated disconnection group alone. Seven patients from the definitive abutment group versus nine patients from the repeated disconnection group were affected by complications (difference =-5.9%; CI95%:-26.0% to 14.2%; P = 0.775), the difference being not statistically significant. PES scores assessed at 5 years post-loading were 12.1±1.8 for the definitive abutment group and 11.9±1.7 for the repeated abutment changes group (difference = 0.2; CI95%:-0.7 to 1.1; P = 0.615); however, there was a statistically significant difference of 0.20 out of a maximum score of 2 in favour of the definitive abutment group for soft tissue contour alone (P = 0.045). Buccal recessions at 5 years post-loading amounted to-0.19±0.77 mm for the definitive abutment group and-0.07±1.24 mm for the repeated abutment changes group (difference = 0.12 mm CI95%:-0.42 to 0.66; P = 0.662). All patients declared being very satisfied or sati-sfied with the function and aesthetics of their prosthesis and would undergo the same procedure again. Mean peri-implant marginal bone loss 5 years after loading was 0.11±0.30 mm for the definitive abutment group and 0.48±0.73 mm for the repeated abutment change group (difference =-0.37 [SE=0.14] mm; CI95%:-0.66 to-0.09; P = 0.012), the difference being statistically significant. The height of keratinised mucosa at 5 years post-loading was 2.81±1.46 mm in the definitive abutment group and 2.83±1.84 mm in the repeated abutment change group (difference =-0.02 mm; CI95%:-0.85 to 0.80; P = 0.956), and there were no significant differences in marginal bone loss (difference = 0.00 mm; CI95%:-0.32 to 0.32, P = 0.990) or buccal recession (difference = 0.05 mm, CI95%:-0.43 to 0.54, P = 0.826) at implants having less than 2 mm of keratinised mucosa at loading compared to those having more than 2 mm of keratinised mucosa. CONCLUSIONS. Five-year post-loading data show that at least three repeated abutment disconnections significantly increased bone loss by 0.37 mm when compared to no di-sconnection, but this difference may not be clinically significant. While it might be advi-sable to avoid unnecessary abutment disconnection whenever possible, if disconnections are required, no clinically significant side effects may be expected. Immediately non-oc-clusally loaded dental implants are a viable alternative to conventional loading, and no increased bone loss or buccal recessions were noted even at implants with less than 2 mm of keratinised mucosa

Two-to-one resonant multi-modal dynamics of horizontal/inclined cables. Part I : theoretical formulation and model validation

This paper is first of the two papers dealingwith analytical investigation of resonant multimodal dynamics due to 2:1 internal resonances in the finite-amplitude free vibrations of horizontal/inclined cables. Part I deals with theoretical formulation and validation of the general cable model. Approximate nonlinear partial differential equations of 3-D coupled motion of small sagged cables - which account for both spatio-temporal variation of nonlinear dynamic tension and system asymmetry due to inclined sagged configurations - are presented. A multidimensional Galerkin expansion of the solution ofnonplanar/planar motion is performed, yielding a complete set of system quadratic/cubic coefficients. With the aim of parametrically studying the behavior of horizontal/inclined cables in Part II [25], a second-order asymptotic analysis under planar 2:1 resonance is accomplished by the method of multiple scales. On accounting for higher-order effectsof quadratic/cubic nonlinearities, approximate closed form solutions of nonlinear amplitudes, frequencies and dynamic configurations of resonant nonlinear normal modes reveal the dependence of cable response on resonant/nonresonant modal contributions. Depending on simplifying kinematic modeling and assigned system parameters, approximate horizontal/inclined cable models are thoroughly validated by numerically evaluating statics and non-planar/planar linear/non-linear dynamics against those of the exact model. Moreover, the modal coupling role and contribution of system longitudinal dynamics are discussed for horizontal cables, showing some meaningful effects due to kinematic condensation

Tracing dark energy history with gamma ray bursts

Observations of gamma-ray bursts up to $z\sim 9$ are best suited to study the possible evolution of the Universe equation of state at intermediate redshifts. We apply the Combo-relation to a sample of 174 gamma ray bursts to investigate possible evidence of evolving dark energy parameter $w(z)$. We first build a gamma ray burst Hubble's diagram and then we estimate the set ($\Omega_m$, $\Omega_{\Lambda}$) in the framework of flat and non-flat $\Lambda$CDM paradigm. We then get bounds over the $w$CDM model, where $w$ is thought to evolve with redshift, adopting two priors over the Hubble constant in tension at $4.4$-$\sigma$, i.e. $H_0=(67.4\pm0.5)$ km/s/Mpc and $H_0=(74.03\pm1.42)$ km/s/Mpc. We show our new sample provides tighter constraints on $\Omega_m$ since at $z\leq1.2$ we see that $w(z)$ agrees within 1$\sigma$ with the standard value $w=-1$. The situation is the opposite at larger $z$, where gamma ray bursts better fix $w(z)$ that seems to deviate from $w=-1$ at $2$-$\sigma$ and $4$-$\sigma$ level, depending on the redshift bins. In particular, we investigate the $w(z)$ evolution through a piecewise formulation over seven redshift intervals. From our fitting procedure we show that at $z\geq 1.2$ the case $w<-1$ cannot be fully excluded, indicating that dark energy's influence is not negligible at larger $z$. We confirm the Combo relation as a powerful tool to investigate cosmological evolution of dark energy. Future space missions will significantly enrich the gamma ray burst database even at smaller redshifts, improving de facto the results discussed in this paper.Comment: 10 pages, 7 figures, ApJ submitte

Mitochondrial calcium exchange links metabolism with the epigenome to control cellular differentiation.

Fibroblast to myofibroblast differentiation is crucial for the initial healing response but excessive myofibroblast activation leads to pathological fibrosis. Therefore, it is imperative to understand the mechanisms underlying myofibroblast formation. Here we report that mitochondrial calcium (mCa2+) signaling is a regulatory mechanism in myofibroblast differentiation and fibrosis. We demonstrate that fibrotic signaling alters gating of the mitochondrial calcium uniporter (mtCU) in a MICU1-dependent fashion to reduce mCa2+ uptake and induce coordinated changes in metabolism, i.e., increased glycolysis feeding anabolic pathways and glutaminolysis yielding increased α-ketoglutarate (αKG) bioavailability. mCa2+-dependent metabolic reprogramming leads to the activation of αKG-dependent histone demethylases, enhancing chromatin accessibility in loci specific to the myofibroblast gene program, resulting in differentiation. Our results uncover an important role for the mtCU beyond metabolic regulation and cell death and demonstrate that mCa2+ signaling regulates the epigenome to influence cellular differentiation

Motion of stars near the galactic center

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