On the dynamics of clouds in the broad-line region of AGNs with an ADAF atmosphere

We investigate orbital motion of spherical, pressure-confined clouds in the broad-line region (BLR) of active galactic nuclei (AGN). The combined influence of gravity of the central object and the non-isotropic radiation of the central source are taking into account. While most of the previous studies assume that the pressure of the intercloud gaseous component is proportional to a power-law function of the radial coordinate, we generalize it to a case where the external pressure depends on both the radial distance and the latitudinal angle. Our prescribed pressure profile determines the radius and the column density of BLR clouds as a function of their location. We also discuss about stability of the orbits and a condition for the existence of bound orbits is obtained. We found that BLR clouds tend to populate the equatorial regions more than other parts simply because of the stability considerations. Although this finding is obtained for a particular pressure profile, we think, this result is valid as long as the pressure distribution of the intercloud medium decreases from the equator to the pole.Comment: Accepted for publication in MNRA

Adaptive Optics in Ophthalmology

Backgraound: Adaptive Optics (AO) has emerged as a powerful imaging tool in ophthalmology, enabling high-resolution visualization of retinal structures in vivo. This technology, initially inspired by astronomy, has opened new avenues for diagnosis, monitoring, and treatment of various eye diseases. This paper aims to provide a comprehensive overview of AO in ophthalmology, highlighting its principles, different types of AO systems, and their clinical applications.Material and Methods: A thorough review of the literature was conducted to gather information on the principles, components, and advancements in AO technology. Clinical studies and research articles involving the use of AO in ophthalmology were analyzed to identify its diverse applications.Results: AO utilizes wavefront sensing and correction techniques to compensate for aberrations in the eye, enabling detailed imaging of the retina at a cellular level. Different AO modalities, including AO scanning laser ophthalmoscopy (AO-SLO) and AO optical coherence tomography (AO-OCT), offer unique capabilities in visualizing cellular structures, tracking disease progression, and evaluating treatment efficacy. Clinical applications of AO span a wide range of eye diseases, including age-related macular degeneration, diabetic retinopathy, glaucoma, and inherited retinal dystrophies. Conclusions: AO has significantly contributed to our understanding of retinal diseases by providing unprecedented insights into cellular-level changes. It holds immense potential for advancing clinical management, personalized treatment strategies, and improving patient outcomes. Further advancements in AO technology, standardization of imaging protocols, and larger-scale clinical studies are crucial for its widespread adoption in routine clinical practice

On the dynamics of pebbles in protoplanetary disks with magnetically-driven winds

We present an analytical model to investigate the production of pebbles and their radial transport through a protoplanetary disk (PPD) with magnetically driven winds. While most of the previous analytical studies in this context assume that the radial turbulent coefficient is equal to the vertical dust diffusion coefficient, in the light of the results of recent numerical simulations, we relax this assumption by adopting effective parametrisations of the turbulent coefficients involved in terms of the strength of the magnetic fields driving the wind. Theoretical studies have already pointed out that even in the absence of winds, these coefficients are not necessarily equal, though its consequences regarding pebble production have not been explored. In this paper, we investigate the evolution of the pebble production line, the radial mass flux of the pebbles and their corresponding surface density as a function of the plasma parameter at the disk midplane. Our analysis explicitly demonstrates that the presence of magnetically-driven winds in a PPD leads to considerable reduction of the rate and duration of the pebble delivery. We show that when the wind is strong, the core growth in mass due to the pebble accretion is so slow that it is unlikely that a core could reach a pebble isolation mass during a PPD lifetime. When the mass of a core reaches this critical value, pebble accretion is halted due to core-driven perturbations in the gas. With decreasing wind strength, however, pebble accretion may, in a shorter time, increase the mass of a core to the pebble isolation mass.Comment: 15 pages, accepted for publication in Ap