Exact General Relativistic Disks with Magnetic Fields

The well-known ``displace, cut, and reflect'' method used to generate cold disks from given solutions of Einstein equations is extended to solutions of Einstein-Maxwell equations. Four exact solutions of the these last equations are used to construct models of hot disks with surface density, azimuthal pressure, and azimuthal current. The solutions are closely related to Kerr, Taub-NUT, Lynden-Bell-Pinault and to a one-soliton solution. We find that the presence of the magnetic field can change in a nontrivial way the different properties of the disks. In particular, the pure general relativistic instability studied by Bicak, Lynden-Bell and Katz [Phys. Rev. D47, 4334, 1993] can be enhanced or cured by different distributions of currents inside the disk. These currents, outside the disk, generate a variety of axial symmetric magnetic fields. As far as we know these are the first models of hot disks studied in the context of general relativity.Comment: 21 pages, 11 figures, uses package graphics, accepted in PR

Оценка технических возможностей использования отработавших тепловыделяющих сборок реактора ВВЭР-1200 в качестве источника гамма-излучения для радиационно-технологических процессов

Possibility in principle of VVER-1200 spent fuel assemblies utilization as a source of gamma radiation for radiotechnology is grounded. The possibility is revealed because of high burn­up fraction of nuclear fuel in recent power reactors.Обосновывается принципиальная возможность использования отработавших тепловыделяющих сборок реактора ВВЭР-1200 в качестве источника гамма-излучения для решения задач радиационной технологии. Такая возможность открывается благодаря высокой глубине выгорания ядерного топлива в современных энергетических реакторах

Evidence of a Sticky Boundary Layer in Nanochannels: A Neutron Spin Echo Study of n

Neutron spin echo spectra of the melts of n-hexatriacontane (C36) and poly(ethylene oxide) (PEO), 2 kg/mol, confined in circular channels with a mean diameter of 10 and 12 nm, respectively, in porous silicon, were recorded at Q values between 0.05 and 0.15 angstrom(-1). The spectra were successfully analyzed in terms of a two-state model where wall-adsorbed molecules are immobile and free molecules have a bulk-like dynamics. For C36, we find an adsorbed bilayer at 364 K and a monolayer at 435 K (in both cases, the long axis of the molecules is oriented parallel to the surface) and no adsorbed layer at 512 K. For PEO, we find an adsorbed monolayer at 413 K. The results support the existence of a sticky boundary layer inferred from capillary filling experiments