Topical prostaglandin analogues and conjunctival inflammation in uveitic glaucoma.

A pilot study to determine whether topical prostaglandin analogues alter the expression of conjunctival inflammatory markers in patients with uveitic glaucoma.Prospective, single-masked case series of 20 patients with uveitis and secondary raised intraocular pressure. Participants were divided into four groups of five patients dependent on their use of topical medication: (1) prostaglandin analogues only, (2) corticosteroids only, (3) both prostaglandin analogues and corticosteroids, (4) no topical medication. Conjunctival cells were harvested by impression cytology and were examined for inflammatory markers (CD3, CD54, HLA-DR, CCR4, CCR5) by flow cytometry. A tear fluid sample was also examined for inflammatory cytokines (IL-12p70, IL-2, IL-10, IL-8, IL-6, IL-4, IL-5, IFN-gamma, IL-1beta, IFN-alpha, IFN-beta) by multiplex bead arrays.All groups demonstrated increased markers of conjunctival inflammation. There was no significant difference in levels of any inflammatory markers between the four groups, suggesting that the use of topical prostaglandin analogues does not increase conjunctival levels of inflammation beyond those already seen in uveitis.The use of topical prostaglandins does not appear to induce conjunctival inflammation over that which is already present in patients with uveitic glaucoma. This supports the use of topical prostaglandin analogues in patients with uveitic glaucoma, indicating that their use is unlikely to adversely affect subsequent glaucoma filtration surgery through the induction of chronic conjunctival inflammation

Fundamental studies in X-ray astrophysics

An analytical model calculation of the ionization structure of matter accreting onto a degenerate dwarf was carried out. Self-consistent values of the various parameters are used. The possibility of nuclear burning of the accreting matter is included. We find the blackbody radiation emitted from the stellar surface keeps hydrogen and helium ionized out to distances much larger than a typical binary separation. Except for low mass stars or high accretion rates, the assumption of complete ionization of the elements heavier than helium is a good first approximation. For low mass stars or high accretion rates the validity of assuming complete ionization depends sensitivity on the distribution of matter in the binary system

Absorption of dark matter by a supermassive black hole at the Galactic center: role of boundary conditions

The evolution of the dark matter distribution at the Galactic center is analyzed, which is caused by the combination of gravitational scattering on Galactic bulge stars and absorption by a supermassive black hole at the center of the bulge. Attention is focused on the boundary condition on the black hole. It is shown that its form depends on the energy of dark matter particles. The modified flux of dark matter particles onto the black hole is calculated. Estimates of the amount of dark matter absorbed show that the fraction of dark matter in the total mass of the black hole may be significant. The density of dark matter at the central part of the bulge is calculated. It is shown that recently observed gamma radiation from the Galactic center can be attributed to the annihilation of dark matter with this density.Comment: 5 page

Particles with negative energies in black holes

The problem of the existence of particles with negative energies inside and outside of Schwarzschild, charged and rotating black holes is investigated. Different definitions of the energy of the particle inside the Schwarzschild black hole are analyzed and it is shown in what cases this energy can be negative. A comparison is made for the cases of rotating black holes described by the Kerr metric when the energy of the particle can be negative in the ergosphere and the Reissner-Nordstrom metric.Comment: 10 pages, 2 figures, typos correction to match published versio

Vogt-Koyanagi-Harada syndrome - current perspectives

Vogt-Koyanagi-Harada syndrome is a cause of noninfectious panuveitis, leading to significant vision loss in many patients. It is an autoimmune disease occurring in genetically susceptible individuals and clinically presents as bilateral panuveitis with serous retinal detachments and hyperemic, swollen optic discs, which are associated with neurological and auditory manifestations. Early diagnosis and prompt and adequate treatment with immunosuppressive agents (corticosteroids and other immunosuppressive drugs) may halt disease progression and prevent recurrences and vision loss. This review summarizes the current knowledge on the variable clinical aspects of this disease, highlighting diagnostic and treatment strategies

A new numerical method to construct binary neutron star initial data

We present a new numerical method for the generation of binary neutron star initial data using a method along the lines of the the Wilson-Mathews or the closely related conformal thin sandwich approach. Our method uses six different computational domains, which include spatial infinity. Each domain has its own coordinates which are chosen such that the star surfaces always coincide with domain boundaries. These properties facilitate the imposition of boundary conditions. Since all our fields are smooth inside each domain, we are able to use an efficient pseudospectral method to solve the elliptic equations associated with the conformal thin sandwich approach. Currently we have implemented corotating configurations with arbitrary mass ratios, but an extension to arbitrary spins is possible. The main purpose of this paper is to introduce our new method and to test our code for several different configurations.Comment: 18 pages, 8 figures, 1 tabl

El físico como novelista

Este trabajo trata sobre las diferencias y semejanzas entre la ciencia y la literatura. Basándome en mi experiencia como físico y como novelista, intento descifrar las características de estas dos pasiones que tengo en la vida. Aunque existen diferencias notables tanto en la naturaleza de lo que se escribe como en las normas que rigen estos dos mundos, en ambos casos hay una experiencia creativa y una necesidad de contraste con nuestras experiencias vividas.Palabras claves: ciencia, literatura científica, novela.The Physicist as novelistThis paper deals with the differences and similarities between science and literature. Based on my experience as a physicist and novelist, I try to decipher the characteristics of these two passions that I have in life. Although there are notable differences in the nature of what is written and in the norms governing these two worlds, in both cases there is a creative experience and a need for contrast with our lived experiences.Keywords: science, scientific literature, novel.

Extended Quintessence with non-minimally coupled phantom scalar field

We investigate evolutional paths of an extended quintessence with a non-minimally coupled phantom scalar field $\psi$ to the Ricci curvature. The dynamical system methods are used to investigate typical regimes of dynamics at the late time. We demonstrate that there are two generic types of evolutional scenarios which approach the attractor (a focus or a node type critical point) in the phase space: the quasi-oscillatory and monotonic trajectories approach to the attractor which represents the FRW model with the cosmological constant. We demonstrate that dynamical system admits invariant two-dimensional submanifold and discussion that which cosmological scenario is realized depends on behavior of the system on the phase plane $(\psi, \psi')$. We formulate simple conditions on the value of coupling constant $\xi$ for which trajectories tend to the focus in the phase plane and hence damping oscillations around the mysterious value $w=-1$. We describe this condition in terms of slow-roll parameters calculated at the critical point. We discover that the generic trajectories in the focus-attractor scenario come from the unstable node. It is also investigated the exact form of the parametrization of the equation of state parameter $w(z)$ (directly determined from dynamics) which assumes a different form for both scenarios.Comment: revtex4, 15 pages, 9 figures; (v2) published versio

Accretion process onto super-spinning objects

The accretion process onto spinning objects in Kerr spacetimes is studied with numerical simulations. Our results show that accretion onto compact objects with Kerr parameter (characterizing the spin) $|a| M$ is very different. In the super-spinning case, for $|a|$ moderately larger than $M$, the accretion onto the central object is extremely suppressed due to a repulsive force at short distance. The accreting matter cannot reach the central object, but instead is accumulated around it, forming a high density cloud that continues to grow. The radiation emitted in the accretion process will be harder and more intense than the one coming from standard black holes; e.g. $\gamma$-rays could be produced as seen in some observations. Gravitational collapse of this cloud might even give rise to violent bursts. As $|a|$ increases, a larger amount of accreting matter reaches the central object and the growth of the cloud becomes less efficient. Our simulations find that a quasi-steady state of the accretion process exists for $|a|/M \gtrsim 1.4$, independently of the mass accretion rate at large radii. For such high values of the Kerr parameter, the accreting matter forms a thin disk at very small radii. We provide some analytical arguments to strengthen the numerical results; in particular, we estimate the radius where the gravitational force changes from attractive to repulsive and the critical value $|a|/M \approx 1.4$ separating the two qualitatively different regimes of accretion. We briefly discuss the observational signatures which could be used to look for such exotic objects in the Galaxy and/or in the Universe.Comment: 11 pages, 5 figures. v2: with explanation of the origin of the critical value |a|/M = 1.

Thermal and Dynamical Equilibrium in Two-Component Star Clusters

We present the results of Monte Carlo simulations for the dynamical evolution of star clusters containing two stellar populations with individual masses m1 and m2 > m1, and total masses M1 and M2 < M1. We use both King and Plummer model initial conditions and we perform simulations for a wide range of individual and total mass ratios, m2/m1 and M2/M1. We ignore the effects of binaries, stellar evolution, and the galactic tidal field. The simulations use N = 10^5 stars and follow the evolution of the clusters until core collapse. We find that the departure from energy equipartition in the core follows approximately the theoretical predictions of Spitzer (1969) and Lightman & Fall (1978), and we suggest a more exact condition that is based on our results. We find good agreement with previous results obtained by other methods regarding several important features of the evolution, including the pre-collapse distribution of heavier stars, the time scale on which equipartition is approached, and the extent to which core collapse is accelerated by a small subpopulation of heavier stars. We briefly discuss the possible implications of our results for the dynamical evolution of primordial black holes and neutron stars in globular clusters.Comment: 31 pages, including 13 figures, to appear in Ap