8 research outputs found
Circular geodesics and thick tori around rotating boson stars
Accretion disks play an important role in the evolution of their relativistic
inner compact objects. The emergence of a new generation of interferometers
will allow to resolve these accretion disks and provide more information about
the properties of the central gravitating object. Due to this instrumental leap
forward it is crucial to investigate the accretion disk physics near various
types of inner compact objects now to deduce later constraints on the central
objects from observations. A possible candidate for the inner object is the
boson star. Here, we will try to analyze the differences between accretion
structures surrounding boson stars and black holes. We aim at analysing the
physics of circular geodesics around boson stars and study simple thick
accretion tori (so-called Polish doughnuts) in the vicinity of these stars. We
realize a detailed study of the properties of circular geodesics around boson
stars. We then perform a parameter study of thick tori with constant angular
momentum surrounding boson stars. This is done using the boson star models
computed by a code constructed with the spectral solver library KADATH. We
demonstrate that all the circular stable orbits are bound. In the case of a
constant angular momentum torus, a cusp in the torus surface exists only for
boson stars with a strong gravitational scalar field. Moreover, for each inner
radius of the disk, the allowed specific angular momentum values lie within a
constrained range which depends on the boson star considered. We show that the
accretion tori around boson stars have different characteristics than in the
vicinity of a black hole. With future instruments it could be possible to use
these differences to constrain the nature of compact objects.Comment: Accepted for publication in CQ
Relativistic AGN jets I. The delicate interplay between jet structure, cocoon morphology and jet-head propagation
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Capivasertib in Hormone Receptor-Positive Advanced Breast Cancer.
Background: AKT pathway activation is implicated in endocrine-therapy resistance. Data on the efficacy and safety of the AKT inhibitor capivasertib, as an addition to fulvestrant therapy, in patients with hormone receptor-positive advanced breast cancer are limited.
Methods: In a phase 3, randomized, double-blind trial, we enrolled eligible pre-, peri-, and postmenopausal women and men with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer who had had a relapse or disease progression during or after treatment with an aromatase inhibitor, with or without previous cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor therapy. Patients were randomly assigned in a 1:1 ratio to receive capivasertib plus fulvestrant or placebo plus fulvestrant. The dual primary end point was investigator-assessed progression-free survival assessed both in the overall population and among patients with AKT pathway-altered (PIK3CA, AKT1, or PTEN) tumors. Safety was assessed.
Results: Overall, 708 patients underwent randomization; 289 patients (40.8%) had AKT pathway alterations, and 489 (69.1%) had received a CDK4/6 inhibitor previously for advanced breast cancer. In the overall population, the median progression-free survival was 7.2 months in the capivasertib-fulvestrant group, as compared with 3.6 months in the placebo-fulvestrant group (hazard ratio for progression or death, 0.60; 95% confidence interval [CI], 0.51 to 0.71; P<0.001). In the AKT pathway-altered population, the median progression-free survival was 7.3 months in the capivasertib-fulvestrant group, as compared with 3.1 months in the placebo-fulvestrant group (hazard ratio, 0.50; 95% CI, 0.38 to 0.65; P<0.001). The most frequent adverse events of grade 3 or higher in patients receiving capivasertib-fulvestrant were rash (in 12.1% of patients, vs. in 0.3% of those receiving placebo-fulvestrant) and diarrhea (in 9.3% vs. 0.3%). Adverse events leading to discontinuation were reported in 13.0% of the patients receiving capivasertib and in 2.3% of those receiving placebo.
Conclusions: Capivasertib-fulvestrant therapy resulted in significantly longer progression-free survival than treatment with fulvestrant alone among patients with hormone receptor-positive advanced breast cancer whose disease had progressed during or after previous aromatase inhibitor therapy with or without a CDK4/6 inhibitor. (Funded by AstraZeneca and the National Cancer Institute; CAPItello-291 ClinicalTrials.gov number, NCT04305496.)