Relativistically expanding cylindrical electromagnetic fields

We study relativistically expanding electromagnetic fields of cylindrical geometry. The fields emerge from the side surface of a cylinder and are invariant under translations parallel to the axis of the cylinder. The expansion velocity is in the radial direction and is parametrized by $v=R/(ct)$. We consider force-free magnetic fields by setting the total force the electromagnetic field exerts on the charges and the currents equal to zero. Analytical and semi-analytical separable solutions are found for the relativistic problem. In the non-relativistic limit the mathematical form of the equations is similar to equations that have already been studied in static systems of the same geometry.Comment: 7 pages, 4 figures, accepted by MNRA

Nonradial and nonpolytropic astrophysical outflows VIII. A GRMHD generalization for relativistic jets

Steady axisymmetric outflows originating at the hot coronal magnetosphere of a Schwarzschild black hole and surrounding accretion disk are studied in the framework of general relativistic magnetohydrodynamics (GRMHD). The assumption of meridional self-similarity is adopted for the construction of semi-analytical solutions of the GRMHD equations describing outflows close to the polar axis. In addition, it is assumed that relativistic effects related to the rotation of the black hole and the plasma are negligible compared to the gravitational and other energetic terms. The constructed model allows us to extend previous MHD studies for coronal winds from young stars to spine jets from Active Galactic Nuclei surrounded by disk-driven outflows. The outflows are thermally driven and magnetically or thermally collimated. The collimation depends critically on an energetic integral measuring the efficiency of the magnetic rotator, similarly to the non relativistic case. It is also shown that relativistic effects affect quantitatively the depth of the gravitational well and the coronal temperature distribution in the launching region of the outflow. Similarly to previous analytical and numerical studies, relativistic effects tend to increase the efficiency of the thermal driving but reduce the effect of magnetic self-collimation.Comment: 20 page, Accepted in A&A 10/10/200

Human papillomavirus infection is not related with prostatitis-related symptoms: results from a casecontrol study.

This study highlights that prostatitis-like symptoms are unrelated to HPV infection. Secondary, we highlight the high prevalence of asymptomatic HPV infection among young heterosexual men

Human papillomavirus infection is not related with prostatitis-related symptoms: results from a casecontrol study.

PurposeTo investigate the relationship between human papillomavirus (HPV) infection and prostatitis-related symptoms.Materials and MethodsAll young heterosexual patients with prostatitis-related symptoms attending the same Center from January 2005 to December 2010 were eligible for this case-control study. Sexually active asymptomatic men were considered as the control group. All subjects underwent clinical examination, Meares-Stamey test and DNA-HPV test. Patients with prostatitis-related symptoms and asymptomatic men were compared in terms of HPV prevalence. Moreover, multivariable Cox proportional hazards regression analysis was performed to determine the association between HPV infection and prostatitis-related symptoms.ResultsOverall, 814 out of 2,938 patients (27.7%) and 292 out of 1,081 controls (27.0%) proved positive to HPV. The HPV genotype distribution was as follows: HR-HPV 478 (43.3%), PHR-HPV 77 (6.9%), LR-HPV 187 (16.9%) and PNG-HPV 364 (32.9%). The most common HPV genotypes were: 6, 11, 16, 26, 51, 53 and 81. No difference was found between the two groups in terms of HPV infection (OR 1.03; 95% CI 0.88-1.22; p = 0.66). We noted a statistically significant increase in HPV infection over the period 2005 to 2010 (p < 0.001) in both groups. Moreover, we found a statistically significant increase in HPV 16 frequency from 2005 to 2010 (p = 0.002).ConclusionsThis study highlights that prostatitis-like symptoms are unrelated to HPV infection. Secondary, we highlight the high prevalence of asymptomatic HPV infection among young heterosexual men

Two-component jet simulations: I. Topological stability of analytical MHD outflow solutions

Observations of collimated outflows in young stellar objects indicate that several features of the jets can be understood by adopting the picture of a two-component outflow, wherein a central stellar component around the jet axis is surrounded by an extended disk-wind. The precise contribution of each component may depend on the intrinsic physical properties of the YSO-disk system as well as its evolutionary stage. In this context, the present article starts a systematic investigation of two-component jet models via time-dependent simulations of two prototypical and complementary analytical solutions, each closely related to the properties of stellar-outflows and disk-winds. These models describe a meridionally and a radially self-similar exact solution of the steady-state, ideal hydromagnetic equations, respectively. By using the PLUTO code to carry out the simulations, the study focuses on the topological stability of each of the two analytical solutions, which are successfully extended to all space by removing their singularities. In addition, their behavior and robustness over several physical and numerical modifications is extensively examined. It is found that radially self-similar solutions (disk-winds) always reach a final steady-state while maintaining all their well-defined properties. The different ways to replace the singular part of the solution around the symmetry axis, being a first approximation towards a two-component outflow, lead to the appearance of a shock at the super-fast domain corresponding to the fast magnetosonic separatrix surface. Conversely, the asymptotic configuration and the stability of meridionally self-similar models (stellar-winds) is related to the heating processes at the base of the wind.Comment: Accepted for publication in A&

Analytical time-like geodesics

Time-like orbits in Schwarzschild space-time are presented and classified in a very transparent and straightforward way into four types. The analytical solutions to orbit, time, and proper time equations are given for all orbit types in the form r=r(\lambda), t=t(\chi), and \tau=\tau(\chi), where \lambda\ is the true anomaly and \chi\ is a parameter along the orbit. A very simple relation between \lambda\ and \chi\ is also shown. These solutions are very useful for modeling temporal evolution of transient phenomena near black holes since they are expressed with Jacobi elliptic functions and elliptic integrals, which can be calculated very efficiently and accurately.Comment: 15 pages, 10 figures, accepted by General Relativity and Gravitatio

Nonradial and nonpolytropic astrophysical outflows IX. Modeling T Tauri jets with a low mass-accretion rate

Context: A large sample of T Tauri stars exhibits optical jets, approximately half of which rotate slowly, only at ten per cent of their breakup velocity. The disk-locking mechanism has been shown to be inefficient to explain this observational fact. Aims: We show that low mass accreting T Tauri stars may have a strong stellar jet component that can effectively brake the star to the observed rotation speed. Methods: By means of a nonlinear separation of the variables in the full set of the MHD equations we construct semi- analytical solutions describing the dynamics and topology of the stellar component of the jet that emerges from the corona of the star. Results: We analyze two typical solutions with the same mass loss rate but different magnetic lever arms and jet radii. The first solution with a long lever arm and a wide jet radius effectively brakes the star and can be applied to the visible jets of T Tauri stars, such as RY Tau. The second solution with a shorter lever arm and a very narrow jet radius may explain why similar stars, either Weak line T Tauri Stars (WTTS) or Classical T Tauri Stars (CTTS) do not all have visible jets. For instance, RY Tau itself seems to have different phases that probably depend on the activity of the star. Conclusions: First, stellar jets seem to be able to brake pre-main sequence stars with a low mass accreting rate. Second, jets may be visible only part time owing to changes in their boundary conditions. We also suggest a possible scenario for explaining the dichotomy between CTTS and WTTS, which rotate faster and do not have visible jets

Velocity asymmetries in YSO jets: Intrinsic and extrinsic mechanisms

It is a well established fact that some YSO jets (e.g. RW Aur) display different propagation speeds between their blue and red shifted parts, a feature possibly associated with the central engine or the environment in which the jet propagates. In order to understand the origin of asymmetric YSO jet velocities, we investigate the efficiency of two candidate mechanisms, one based on the intrinsic properties of the system and one based on the role of the external medium. In particular, a parallel or anti-parallel configuration between the protostellar magnetosphere and the disk magnetic field is considered and the resulting dynamics are examined both in an ideal and a resistive magneto-hydrodynamical (MHD) regime. Moreover, we explore the effects of a potential difference in the pressure of the environment, as a consequence of the non-uniform density distribution of molecular clouds. Ideal and resistive axisymmetric numerical simulations are carried out for a variety of models, all of which are based on a combination of two analytical solutions, a disk wind and a stellar outflow. We find that jet velocity asymmetries can indeed occur both when multipolar magnetic moments are present in the star-disk system as well as when non-uniform environments are considered. The latter case is an external mechanism that can easily explain the large time scale of the phenomenon, whereas the former one naturally relates it to the YSO intrinsic properties. [abridged]Comment: accepted for publication in A&

Dynamical Boson Stars

The idea of stable, localized bundles of energy has strong appeal as a model for particles. In the 1950s John Wheeler envisioned such bundles as smooth configurations of electromagnetic energy that he called {\em geons}, but none were found. Instead, particle-like solutions were found in the late 1960s with the addition of a scalar field, and these were given the name {\em boson stars}. Since then, boson stars find use in a wide variety of models as sources of dark matter, as black hole mimickers, in simple models of binary systems, and as a tool in finding black holes in higher dimensions with only a single killing vector. We discuss important varieties of boson stars, their dynamic properties, and some of their uses, concentrating on recent efforts.Comment: 79 pages, 25 figures, invited review for Living Reviews in Relativity; major revision in 201