Relativistic Jets from Accretion Disks

The jets observed to emanate from many compact accreting objects may arise from the twisting of a magnetic field threading a differentially rotating accretion disk which acts to magnetically extract angular momentum and energy from the disk. Two main regimes have been discussed, hydromagnetic jets, which have a significant mass flux and have energy and angular momentum carried by both matter and electromagnetic field and, Poynting jets, where the mass flux is small and energy and angular momentum are carried predominantly by the electromagnetic field. Here, we describe recent theoretical work on the formation of relativistic Poynting jets from magnetized accretion disks. Further, we describe new relativistic, fully-electromagnetic, particle-in-cell simulations of the formation of jets from accretion disks. Analog Z-pinch experiments may help to understand the origin of astrophysical jets.Comment: 7 pages, 3 figures, Proc. of High Energy Density Astrophysics Conf., 200

Risk factors for the preservation of morphological changes in the gastric mucosa after eradication therapy for Helicobacter pylori infection in children with chronic gastritis

We conducted a clinical, morphofunctional examination and standard treatment of 155 children with chronic gastroduodenitis associated with Helicobacter pylori (HP) infection. It was кevealed that after 6 months lymphoplasmacytic infiltration of the gastric mucosa (GM) preserved in 37% of cases, and unspecified atrophy - in 9%, increased C3 and C4 components of the compliment - in 19% of children, antroduodenal discoordination on the background of postprandial secretin and cholecystokinin level - in 25%, as well as disorders of the intestinal microbiot

Relativistic dynamical polarizability of hydrogen-like atoms

Using the operator representation of the Dirac Coulomb Green function the analytical method in perturbation theory is employed in obtaining solutions of the Dirac equation for a hydrogen-like atom in a time-dependent electric field. The relativistic dynamical polarizability of hydrogen-like atoms is calculated and analysed

Particle Acceleration and Magnetic Dissipation in Relativistic Current Sheet of Pair Plasmas

We study linear and nonlinear development of relativistic and ultrarelativistic current sheets of pair plasmas with antiparallel magnetic fields. Two types of two-dimensional problems are investigated by particle-in-cell simulations. First, we present the development of relativistic magnetic reconnection, whose outflow speed is an order of the light speed c. It is demonstrated that particles are strongly accelerated in and around the reconnection region, and that most of magnetic energy is converted into "nonthermal" part of plasma kinetic energy. Second, we present another two-dimensional problem of a current sheet in a cross-field plane. In this case, the relativistic drift kink instability (RDKI) occurs. Particle acceleration also takes place, but the RDKI fast dissipates the magnetic energy into plasma heat. We discuss the mechanism of particle acceleration and the theory of the RDKI in detail. It is important that properties of these two processes are similar in the relativistic regime of T > mc^2, as long as we consider the kinetics. Comparison of the two processes indicates that magnetic dissipation by the RDKI is more favorable process in the relativistic current sheet. Therefore the striped pulsar wind scenario should be reconsidered by the RDKI.Comment: To appear in ApJ vol. 670; 60 pages, 27 figures; References and typos are fixe

Shear-Flow Driven Current Filamentation: Two-Dimensional Magnetohydrodynamic Simulations

The process of current filamentation in permanently externally driven, initially globally ideal plasmas is investigated by means of two-dimensional Magnetohydrodynamic (MHD)-simulations. This situation is typical for astrophysical systems like jets, the interstellar and intergalactic medium where the dynamics is dominated by external forces. Two different cases are studied. In one case, the system is ideal permanently and dissipative processes are excluded. In the second case, a system with a current density dependent resistivity is considered. This resistivity is switched on self-consistently in current filaments and allows for local dissipation due to magnetic reconnection. Thus one finds tearing of current filaments and, besides, merging of filaments due to coalescence instabilities. Energy input and dissipation finally balance each other and the system reaches a state of constant magnetic energy in time.Comment: 32 Pages, 13 Figures. accepted, to appear in Physics of Plasmas (049012

Disk-Magnetosphere Interaction and Outflows: Conical Winds and Axial Jets

We investigate outflows from the disk-magnetosphere boundary of rotating magnetized stars in cases where the magnetic field of a star is bunched into an X-type configuration using axisymmetric and full 3D MHD simulations. Such configuration appears if viscosity in the disk is larger than diffusivity, or if the accretion rate in the disk is enhanced. Conical outflows flow from the inner edge of the disk to a narrow shell with an opening angle 30-45 degrees. Outflows carry 0.1-0.3 of the disk mass and part of the disk's angular momentum outward. Conical outflows appear around stars of different periods, however in case of stars in the "propeller" regime, an additional - much faster component appears: an axial jet, where matter is accelerated up to very high velocities at small distances from the star by magnetic pressure force above the surface of the star. Exploratory 3D simulations show that conical outflows are symmetric about rotational axis of the disk even if magnetic dipole is significantly misaligned. Conical outflows and axial jets may appear in different types of young stars including Class I young stars, classical T Tauri stars, and EXors.Comment: Invited review, conference proceedings of the meeting "Protostellar Jets in Context", 7-12 July 2008, island of Rhodes, Greece; editors: profs. Tom Ray and Kanaris Tsinganos; 10 pages, 10 figures, see animations at http://www.astro.cornell.edu/~romanova/conical.htm and http://www.astro.cornell.edu/~romanova/propeller.ht

Magneto-centrifugally driven winds: comparison of MHD simulations with theory

Stationary magnetohydrodynamic (MHD) outflows from a rotating, conducting Keplerian accretion disk threaded by B-field are investigated numerically by time-dependent, axisymmetric (2.5D) simulations using a Godunov-type code. A large class of stationary magneto-centrifugally driven winds are found where matter is accelerated from a thermal speed at the disk to much larger velocity, greater than the fast magnetosonic speed and larger than the escape speed. The flows are approximately spherical outflows with only small collimation within the simulation region. Numerical results are shown to coincide with the theoretical predictions of ideal, axisymmetric MHD to high accuracy. Investigation of the influence of outer boundary conditions, particularly that on the toroidal component of magnetic field shows that the commonly used ``free'' boundary condition leads to artificial magnetic forces which can act to give spurious collimation. New boundary conditions are proposed which do not generate artificial forces. Artificial results may also arise for cases where the Mach cones on the outer boundaries are partially directed into the simulation region.Comment: 19 pages, 18 figures, emulapj.sty is use

Pollen quality and pollen productivity of blue honeysuckle species and varieties

Studies to assess the pollen quality and pollen productivity of blue honeysuckle were conducted on the ecosystem dendrological territory of the Siberian Botanical garden of TSU (Tomsk). Objects of research: 8 varieties and 4 species of blue honeysuckle – ‘Velvet’, ‘Berel’, ‘Vasyuganskaya’, ‘Zolushka’, ‘Lazurnaya’, ‘Ogneny Opal’, ‘Selena’, ‘Tomichka’, Lonicera altaica, L. edulis, L. kamtschatica, L. turczaninovii. It was found that the ‘Ogneny Opal’ and ‘Velvet’ varieties have low fertility, and the ‘Berel’ and L. edulis have an average fertility. Other varieties and species of honeysuckle have high pollen fertility. The viability of pollen with high values is more than 60 % – ‘Berel’, ‘Vasyuganskaya’, ‘Lazurnaya’, L. turczaninovii, L. kamtschatica, with average values from 40% to 60 % – ‘Selena’, ‘Tomichka’ and L. altaica, with low values – less than 40 % – ‘Velvet’, ‘Zolushka’, ‘Ogneny Opal’ and L. edulis. High pollen productivity – more than 20,000 pollen grains per flower – ‘Tomichka’, L. kamtschatica, L. turczaninovii and L. edulis, average productivity - from 10,000 to 20,000 pollen grains – ‘Berel’, ‘Vasyuganskaya’, ‘Zolushka’, ‘Lazurnaya’, ‘Selena’ and L. altaica, low productivity – less than 10,000 pollen grains per flower – ‘Velvet’, ‘Ogneny Opal’. It is recommended to use at least 10% of varieties with high pollen viability and pollen productivity as pollinators when creating industrial honeysuckle plantations: ‘Lazurnaya’, ‘Vasyuganskaya’, and ‘Berel’

Magnetohydrodynamic jets from different magnetic field configurations

Using axisymmetric MHD simulations we investigate how the overall jet formation is affected by a variation in the disk magnetic flux profile and/or the existence of a central stellar magnetosphere. Our simulations evolve from an initial, hydrostatic equilibrium state in a force-free magnetic field configuration. We find a unique relation between the collimation degree and the disk wind magnetization power law exponent. The collimation degree decreases for steeper disk magnetic field profiles. Highly collimated outflows resulting from a flat profile tend to be unsteady. We further consider a magnetic field superposed of a stellar dipole and a disk field in parallel or anti-parallel alignment. Both stellar and disk wind may evolve in a pair of outflows, however, a reasonably strong disk wind component is essential for jet collimation. Strong flares may lead to a sudden change in mass flux by a factor two. We hypothesize that such flares may eventually trigger jet knots.Comment: 5 pages, 4 figures; proceedings from conference: Protostellar Jets in Context, held in Rhodes, July 7-12, 200