Quantum interference in the classically forbidden region: a parametric oscillator

We study tunneling between period two states of a parametrically modulated oscillator. The tunneling matrix element is shown to oscillate with the varying frequency of the modulating field. The effect is due to spatial oscillations of the wave function and the related interference in the classically forbidden region. The oscillations emerge already in the ground state of the oscillator Hamiltonian in the rotating frame, which is quartic in the momentum.Comment: Submitted to PR

Multiphoton antiresonance in large-spin systems

We study nonlinear response of a spin $S>1/2$ with easy-axis anisotropy. The response displays sharp dips or peaks when the modulation frequency is adiabatically swept through multiphoton resonance. The effect is a consequence of a special symmetry of the spin dynamics in a magnetic field for the anisotropy energy $\propto S_z^2$. The occurrence of the dips or peaks is determined by the spin state. Their shape strongly depends on the modulation amplitude. Higher-order anisotropy breaks the symmetry, leading to sharp steps in the response as function of frequency. The results bear on the dynamics of molecular magnets in a static magnetic field.Comment: Submitted to PR

X-ray line formation in the spectrum of SS 433

The mechanisms for the formation of X-ray lines in the spectrum of SS 433 are investigated by taking into account the radiative transfer inside the jets. The results of Monte Carlo numerical simulations are presented. The effect of a decrease in line intensity due to scattering inside the jet turns out to be pronounced, but it does not exceed 60% in magnitude on the entire grid of parameters. The line broadening due to scattering, nutational motion, and the contribution of satellites can lead to overestimates of the jet opening angle $\Theta$ from the line widths in Chandra X-ray observations. The fine structure of the lines turns out to be very sensitive to the scattering effects. This makes its investigation by planned X-ray observatories equipped with high-resolution spectrometers (primarily Astro-H) a powerful tool for diagnosing the parameters of the jets in SS 433.Comment: 23 pages, 14 figures, to be published in Astronomy Letters, v. 38, n. 7, p. 443 (2012

Relaxation of a qubit measured by a driven Duffing oscillator

We investigate the relaxation of a superconducting qubit for the case when its detector, the Josephson bifurcation amplifier, remains latched in one of its two (meta)stable states of forced vibrations. The qubit relaxation rates are different in different states. They can display strong dependence on the qubit frequency and resonant enhancement, which is due to quasienergy resonances. Coupling to the driven oscillator changes the effective temperature of the qubit.Comment: To appear in Phys. Rev. A (2010

Directional approach to spatial structure of solutions to the Navier-Stokes equations in the plane

We investigate a steady flow of incompressible fluid in the plane. The motion is governed by the Navier-Stokes equations with prescribed velocity $u_\infty$ at infinity. The main result shows the existence of unique solutions for arbitrary force, provided sufficient largeness of $u_\infty$. Furthermore a spacial structure of the solution is obtained in comparison with the Oseen flow. A key element of our new approach is based on a setting which treats the directino of the flow as \emph{time} direction. The analysis is done in framework of the Fourier transform taken in one (perpendicular) direction and a special choice of function spaces which take into account the inhomogeneous character of the symbol of the Oseen system. From that point of view our technique can be used as an effective tool in examining spatial asymptotics of solutions to other systems modeled by elliptic equations

Backward asymmetry of the Compton scattering by an isotropic distribution of relativistic electrons: astrophysical implications

The angular distribution of low-frequency radiation after single scattering by an isotropic distribution of relativistic electrons considerably differs from the Rayleigh angular function. In particular, the scattering by an ensemble of ultra-relativistic electrons obeys the law p=1-cos(alpha), where alpha is the scattering angle; hence photons are preferentially scattered backwards. We discuss some consequences of this fact for astrophysical problems. We show that a hot electron-scattering atmosphere is more reflective than a cold one: the fraction of incident photons which become reflected having suffered a single scattering event can be larger by up to 50 per cent in the former case. This should affect the photon exchange between cold accretion disks and hot coronae or ADAF flows in the vicinity of relativistic compact objects; as well as the rate of cooling (through multiple inverse-Compton scattering of seed photons supplied from outside) of optically thick clouds of relativistic electrons in compact radiosources. The forward-backward scattering asymmetry also causes spatial diffusion of photons to proceed slower in hot plasma than in cold one, which is important for the shapes of Comptonization spectra and the time delays between soft and hard radiations coming from variable X-ray sources.Comment: 20 pages, 3 figures, to appear in Astronomy Letters, added reference

Optical Identification of Four Hard X-ray Sources from the Swift All-Sky Survey

We present the results of our optical identifications of four hard X-ray sources from the Swift all-sky survey. We obtained optical spectra for each of the program objects with the 6-m BTA telescope (Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnii Arkhyz), which allowed their nature to be established. Two sources (SWIFT J2237.2+6324} and SWIFT J2341.0+7645) are shown to belong to the class of cataclysmic variables (suspected polars or intermediate polars). The measured emission line width turns out to be fairly large (FWHM ~ 15-25 A), suggesting the presence of extended, rapidly rotating (v~400-600 km/s) accretion disks in the systems. Apart from line broadening, we have detected a change in the positions of the line centroids for SWIFT J2341.0+7645, which is most likely attributable to the orbital motion of the white dwarf in the binary system. The other two program objects (SWIFT J0003.3+2737 and SWIFT J0113.8+2515) are extragalactic in origin: the first is a Seyfert 2 galaxy and the second is a blazar at redshift z=1.594. Apart from the optical spectra, we provide the X-ray spectra for all sources in the 0.6-10 keV energy band obtained from XRT/Swift data.Comment: 9 pages, 6 figures, will be published in Astronomy Letters, 38, No.5, pp.281-289 (2012

LISTS OF VOCATIONAL EDUCATION PROGRAMMES: STATUS AND POSSIBLE WAYS OF MODERNISATION

Introduction. The liberalisation of state educational standards and the provision of greater autonomy for educational institutions in the formation of educational programmes indicate the need for development of a new classification system for Russian education, which should become common for all types of professional educational programmes, including additional training programmes. The aim of the publication was to discuss the status and possible ways to modernise the system of classification of educational programmes in Russian vocational education, taking into account the prospects of its development and the constant replenishment of the registers of professional standards and qualifications. Methodology and research methods. In the course of the study, a retrospective analysis of the development of the classification system of professional educational programmes was used, during which the best Russian and foreign practices were compared. Results. The features of the current lists of professions and specialties of secondary vocational education and areas of improvement in accordance with modern requirements of the system of classification of professional educational programmes used in these lists were considered. For updated lists, a new composition of enlarged groups of the classification system of vocational education programs has been proposed, coupled with a list of areas of professional activity of the register of professional standards of the Ministry of Labour of Russia. Scientific novelty. For the first time, it is proposed to refuse classifiers that are strictly tied to the lists of professions, specialties and training areas approved by the Ministry of Education and Science, which formally copy these lists. Combining the classification systems of vocational education programmes and areas of professional activity will allow an adequate comparison of statistical information on training in the education system with their actual use in the labour market.Practical significance. The introduction of the proposed classification system allows us more fully to take into account data on the training of specialists in the Russian system of vocational education, to reflect this data as accurately as possible in national and international educational statistics and to correlate them with employment indicators in various sectors of the economy and production.Введение. Либерализация государственных образовательных стандартов и предоставление большей самостоятельности учебным учреждениям в формировании образовательных программ указывают на необходимость разработки для российского образования новой системы классификации, которая должна стать общей для всех типов профессиональных образовательных программ, включая программы дополнительного обучения. Цель публикации – обсуждение состояния и возможных путей модернизации системы классификации образовательных программ в российском профессиональном образовании с учетом перспектив его развития и постоянного пополнения реестров профессиональных стандартов и квалификаций. Методология и методики. В ходе исследования применялся ретроспективный анализ развития системы классификации профессиональных образовательных программ, при проведении которого проводилось сравнение лучших отечественных и зарубежных практик. Результаты. Рассмотрены особенности действующих перечней профессий и специальностей СПО и направления совершенствования в соответствии с современными требованиями используемой в данных перечнях системы классификации профессиональных образовательных программ. Для обновляемых перечней предложен новый состав укрупненных групп системы классификации профессиональных образовательных программ, сопряженный с перечнем областей профессиональной деятельности реестра профессиональных стандартов Министерства труда России. Научная новизна. Впервые предлагается отказаться от классификаторов, жестко привязанных к утверждаемым Министерством образования и науки перечням профессий, специальностей и направлений подготовки, формально копирующих эти перечни. Сопряжение систем классификации профессиональных образовательных программ и областей профессиональной деятельности позволит осуществлять адекватное сопоставление статистической информации о подготовке кадров в системе образования с их реальным использованием на рынке труда. Практическая значимость. Внедрение предлагаемой системы классификации разрешает более полно учитывать данные об обучении специалистов в российской системе профессионального образования, максимально точно отражать эти данные в национальной и международной образовательной статистике и соотносить их с показателями занятости населения в разных сферах экономики и производства

Controlled drug release from electrospun PCL non-woven scaffolds via multi-layering and e-beam treatment

Currently, electrospun synthetic bioresorbable polymer scaffolds are applied in regenerative medicine and tissue engineering as targeted drug delivery devices because of their mechanical and physico-chemical properties. To control the rate of polymer degradation and drug release from polymer scaffolds, surface modification techniques are widely used. In this study, paracetamol-loaded poly (ε-caprolactone) electrospun fibrous scaffolds were treated by the pulsed electron beam irradiation. Pure control PCL scaffold, as well as scaffolds with four paracetamol concentrations (2 wt./wt. %, 8 wt./wt. %, 16 wt./wt. %, and 32 wt./wt.%) were modified. The mechanical and chemical properties and morphology of modified materials were examined. The sustained release of the model drug over a period of one hour for both non-treated and treated samples was demonstrated. It was shown that treatment leads to an increase in drug release rate and does not change surface morphology of scaffolds and fibers diameter distribution