Bound-state beta-decay of a neutron in a strong magnetic field

The beta-decay of a neutron into a bound $(pe^-)$ state and an antineutrino in the presence of a strong uniform magnetic field ($B \gtrsim 10^{13}$ G) is considered. The beta-decay process is treated within the framework of the standard model of weak interactions. A Bethe-Salpeter formalism is employed for description of the bound $(pe^-)$ system in a strong magnetic field. For the field strengths $10^{13}$ G$\lesssim B \lesssim10^{18}$ G the estimate for the ratio of the bound-state decay rate $w_b$ and the usual (continuum-state) decay rate $w_c$ is derived. It is found that in such strong magnetic fields $w_b/w_c \sim 0.1-0.4$. This is in contrast to the field-free case, where $w_b/w_c \simeq 4.2 \times 10^{-6}$ [J. N. Bahcall, Phys. Rev. {\bf 124}, 495 (1961); L. L. Nemenov, Sov. J. Nucl. Phys. {\bf 15}, 582 (1972); X. Song, J. Phys. G: Nucl. Phys. {\bf 13}, 1023 (1987)]. The dependence of the ratio $w_b/w_c$ on the magnetic field strength $B$ exhibits a logarithmic-like behavior. The obtained results can be important for applications in astrophysics and cosmology.Comment: 22 pages (revtex4), 1 figure; v2: more detailed discussion on astrophysical applications in conclusion section, accepted for publication in Phys. Rev.

Relativistic theory of inverse beta-decay of polarized neutron in strong magnetic field

The relativistic theory of the inverse beta-decay of polarized neutron, $\nu _{e} + n \to p + e ^{-}$, in strong magnetic field is developed. For the proton wave function we use the exact solution of the Dirac equation in the magnetic filed that enables us to account exactly for effects of the proton momentum quantization in the magnetic field and also for the proton recoil motion. The effect of nucleons anomalous magnetic moments in strong magnetic fields is also discussed. We examine the cross section for different energies and directions of propagation of the initial neutrino accounting for neutrons polarization. It is shown that in the super-strong magnetic field the totally polarized neutron matter is transparent for neutrinos propagating antiparallel to the direction of polarization. The developed relativistic approach can be used for calculations of cross sections of the other URCA processes in strong magnetic fields.Comment: 41 pages in LaTex including 11 figures in PostScript, discussion on nucleons AMM interaction with magnetic field is adde

Black-hole concept of a point-like nucleus with supercritical charge

The Dirac equation for an electron in the central Coulomb field of a point-like nucleus with the charge greater than 137 is considered. This singular problem, to which the fall-down onto the centre is inherent, is addressed using a new approach, based on a black-hole concept of the singular centre and capable of producing cut-off-free results. To this end the Dirac equation is presented as a generalized eigenvalue boundary problem of a self-adjoint operator. The eigenfunctions make complete sets, orthogonal with a singular measure, and describe particles, asymptotically free and delta-function-normalizable both at infinity and near the singular centre $r=0$. The barrier transmission coefficient for these particles responsible for the effects of electron absorption and spontaneous electron-positron pair production is found analytically as a function of electron energy and charge of the nucleus. The singular threshold behaviour of the corresponding amplitudes substitutes for the resonance behaviour, typical of the conventional theory, which appeals to a finite-size nucleus.Comment: 22 pages, 5 figures, LATEX requires IOPAR

Профилактика и лечение железодефицитной анемии у детей первого года жизни

The article presents features of physiological processes and pathological conditions in under one-year children that predispose the development of iron-deficiency anemia. Basic methods of iron deficiency prophylaxis and principles of iron drug selection and dose selection for iron-deficiency anemia treatment for children in the stated age category are described in the article. Particular attention is paid to the prevention and treatment of iron deficiency anemia in preterm infants; foreign and domestic recommendations on this issue are presented. A practicing pediatrician needs to know the features of the disease’s development and treatment caused by differences in physical conditions accompanied by a high activity of metabolic processes and the immaturity of the young patients’ anatomic structures in order to identifiy and select the right iron-deficiency anemia treatment strategy.В статье представлены особенности физиологических процессов и патологических состояний у детей первого года жизни, предрасполагающих к развитию железодефицитной анемии (ЖДА). Описаны основные способы профилактики железодефицитных состояний, а также принципы выбора препарата железа и его дозы для лечения ЖДА у детей указанной возрастной категории. Особое внимание уделено профилактике и лечению ЖДА у недоношенных детей, представлены зарубежные и отечественные рекомендации по данному вопросу. Практикующему педиатру для своевременного выявления и выбора правильной тактики лечения ЖДА у детей первых 12 мес жизни необходимы знания об особенностях развития и лечения патологии, обусловленных отличиями физиологического состояния на фоне высокой интенсивности обменных процессов и незрелости анатомических структур у маленьких пациентов

AUDIOVISUAL METHOD IN TEACHING ADULT LEARNERS

One of the aims of teaching adults foreign languages is considered to be the development of students' linguistic consciousness and the ability to draw the analogy between a foreign language and a mother tongue. To make the process of teaching more productive, it is necessary to make certain working environment that can motivate students boost their creativity. In this connection audiovisual method proves to be effective. Adult learners frequently face various psychological problems. The usage of audiovisual method can help to overcome these difficulties and make the learning process less stressful. The article deals with the benefits of the usage of audiovisual method when teaching adult learners and provides a deep analysis of such type of video material as authentic feature films. Our purpose was to make a complex of language exercises based on audiovisual method that aims at developing both receptive and productive skills that led us to elaborate the methodology of working with authentic feature films, the structure, the stages and the content of the lesson created on the basis of animated cartoon and feature films. The complex of exercises was tested in a group of students who demonstrated significant progress in listening and speaking skills after 12 weeks of studying. The students' vocabulary considerably expanded, they showed a greater interest in English classes and became more engaged in the studying process

Clinical and economic efficacy of ribosomal therapy in children in the prevention of acute respiratory infections

The article tells about the problem of acute respiratory infections in preschool children. Pharmacoeconomic efficacy of ribosomal immunomodulatory therapy for the prevention of acute respiratory infections is evaluated. The study found that ribosomal therapy with Ribomunyl has financial benefits and allows to dwindle almost by half the cost of treatment of acute respiratory infections within 2 years after treatment