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.Comment: 15 pages, 3 figures (not included, but hard copies are available upon request

Development of metacognitive competencies of students in the process of constructing mathematical problems for younger students

The article presents a description of the study of the effectiveness of methodological tools aimed at developing metacognitive competence in future elementary school teachers in the classroom on the methodology of teaching mathematics to younger students.The aim of the study is to empirically test the effectiveness of a set of methodological techniques used in the classroom on the methodology of teaching mathematics to future elementary school teachers as a means of developing their metacognitive competencies. The hypothesis of the study is the assumption that one of the effective means of developing metacognitive competencies in future elementary school teachers is special classes for compiling original scenarios of verbal mathematical problems for younger students. A professionally developed verbal composition of a mathematical problem sets the vector of mental activity for the younger student. It requires the developer to build a forecast of the child’s mental actions, determine algorithms and levels of difficulty in obtaining the right solution. The study used methods for testing students’ cognitive characteristics (intelligence) and peer review of their “metacognitive knowledge”, “metacognitive skills”, “metacognitive experience” and “metacognitive strategies”. The methodological solutions implemented in the classroom have shown their effectiveness. For the practice of preparing future primary school teachers, it is important that the well-organized development of compositions of textual mathematical problems for younger students is an effective means of developing their metacognitive competencies

Non-thermal Processes in Black-Hole-Jet Magnetospheres

The environs of supermassive black holes are among the universe's most extreme phenomena. Understanding the physical processes occurring in the vicinity of black holes may provide the key to answer a number of fundamental astrophysical questions including the detectability of strong gravity effects, the formation and propagation of relativistic jets, the origin of the highest energy gamma-rays and cosmic-rays, and the nature and evolution of the central engine in Active Galactic Nuclei (AGN). As a step towards this direction, this paper reviews some of the progress achieved in the field based on observations in the very high energy domain. It particularly focuses on non-thermal particle acceleration and emission processes that may occur in the rotating magnetospheres originating from accreting, supermassive black hole systems. Topics covered include direct electric field acceleration in the black hole's magnetosphere, ultra-high energy cosmic ray production, Blandford-Znajek mechanism, centrifugal acceleration and magnetic reconnection, along with the relevant efficiency constraints imposed by interactions with matter, radiation and fields. By way of application, a detailed discussion of well-known sources (Sgr A*; Cen A; M87; NGC1399) is presented.Comment: invited review for International Journal of Modern Physics D, 49 pages, 15 figures; minor typos corrected to match published versio

Эффективность и переносимость комбинированного медленнодействующего симптоматического препарата глюкозамина и хондроитина сульфата у больных гонартрозом, не принимающих нестероидные противовоспалительные препараты

Objective: to evaluate the efficacy and tolerability of the combined symptomatic slow-acting combined agent Theraflex in gonarthrosis patients untreated with nonsteroidal antiinflammatory drugs (NSAIDs).Patients and methods. The investigation enrolled 84 patients (78 women and 6 men) aged 55.23±7.36 years with knee arthritis lasting 6.2±0.98 years who were blindly randomized into 2 groups. A study group took Theraflex (chondroitin sulfate 400 mg and glucosamine sulfate 500 mg) with or without acetaminophen. A comparison group received acetaminophen only. At baseline and 3 and 6 months after treatment, the investigators assessed changes in the magnitude of osteoarthritis (OA) using WOMAC and Lequen's indices, evaluated the therapeutic efficiency rated by a patient and a physician according to the visual analogue scale, and took into account adverse reactions (AR).Results. All the patients taking Theraflex for 6 months showed a positive effect in substantially lowering WOMAC and Lequen's indices and reducing pain and needs for analgesics as compared to both the values at baseline and those obtained in the patients receiving acetaminophen only.Conclusion. In osteoarthritis patients untreated with NSAIDs, Theraflex treatment was associated with a reduction in pain syndrome and stiffness and with better function and lower needs for analgesics. Six-month Theraflex therapy did not cause serious ARs, as well as in patients having controlled gastrointestinal and renal diseases and hypertensionЦель исследования – оценка эффективности и переносимости комбинированного симтоматического препарата замедленного действия терафлекс у пациентов с гонартрозом, не принимающих нестероидные противовоспалительные препараты (НПВП).Пациенты и методы. В исследование включено 84 пациента с артрозом коленного сустава (возраст 55,23±7,36 года, продолжительность заболевания – 6,2±0,98 года, женщины/мужчины – 78/6), рандомизированных вслепую в две группы. Пациенты основной группы получали терафлекс (400 мг хондроитина сульфата и 500 мг глюкозамина сульфата) с/без ацетаминофена, пациенты группы сравнения – только ацетаминофен. Исходно и через 3 и 6 мес лечения оценивали изменение выраженности остеоартроза (ОА) с применением индексов WOMAC, Лекена, проводили оценку эффективности лечения врачом и пациентом по визуальной аналоговой шкале, учитывали нежелательные реакции (НР).Результаты. У всех пациентов, принимавших терафлекс на протяжении 6 мес, отмечен положительный эффект, выразившийся в существенном снижении индексов WOMAC, Лекена, уменьшении болевого синдрома и потребности в анальгетиках по сравнению как с исходными показателями, так и с показателями у пациентов, получавших только ацетаминофен. Сделан вывод, что у пациентов с ОА, не получавших НПВП, лечение терафлексом ассоциировалось с уменьшением болевого синдрома, скованности и улучшением функции при одновременном уменьшении потребности в приеме анальгетиков. На фоне 6-месячного применения терафлекса не зафиксировано серьезных НР, в том числе у пациентов, имевших контролируемую патологию желудочно-кишечного тракта, почек и артериальную гипертензию

Кардиоваскулярная безопасност ь и эффективность комбинированного медленнодействующего симптоматического препарата глюкозамина и хондроитина сульфата1 у больных гонартрозом

Objective: to investigate the clinical efficacy and cardiovascular safety of the combined symptomatic slow-acting drug glucosamine and chondroitin sulfate in patients with osteoarthritis (OA) and hypertension.Subjects and methods. The investigation enrolled 44 patients (a female:male ratio of 40:4) aged 54.5±7.4 years with knee OA (duration, 6.4±1.54 years). The patients were blindly randomized into two groups: 1) those who received antihypertensive therapy, teraflex (chondroitin sulfate 400 mg and glucosamine sulfate 500 mg) with/without acetaminophen; 2) those who had antihypertensive therapy and acetaminophen. At baseline and 3 and 6 months after treatment, the investigators assessed a change in the degree of OA by the WOMAC and Lequesne indices, the treatment efficiency evaluated by a physician and a patient using a visual analogue scale, and cardiovascular safety (during the first and last visits) through examination of the antithrombogenic properties of the vascular wall and arterial stiffness.Results. All the patients taking teraflex for 6 months were observed to have a positive effect manifesting as a substantial reduction in WOMAC and Lequesne indices, pain syndrome, and needs for analgesics compared to both the baseline level and parameters in the patients receiving acetaminophen only. Teraflex therapy showed an increase in the fibrinolytic activity of the vascular wall. A more obvious fall in augmentation index and pulse wave velocity was seen in OA and AG patients receiving antihypertensive therapy and teraflex.Conclusion. Group 1 displayed not only reductions in pain syndrome and needs for analgesics, but also no blood pressure destabilization. They also had lower endothelial dysfunction manifesting as enhanced fibrinolytic activity of the vascular wall, decreased brachial and aortic augmentation indices, and lower pulse wave velocity.Цель исследования – изучение клинической эффективности и кардиоваскулярной безопасности комбинированного медленнодействующего симптоматического препарата глюкозамина и хондроитина сульфата у пациентов с остеоартритом (ОА) и артериальной гипертензией (АГ).Материал и методы. В исследование включено 44 пациента с ОА коленного сустава (возраст – 54,5±7,4 года, продолжительность заболевания – 6,4±1,54 года, женщины/мужчины – 40/4). Пациенты рандомизированы вслепую в две группы: пациенты 1-й группы получали антигипертензивную терапию, терафлекс (400 мг хондроитина сульфата и 500 мг глюкозамина сульфата) с (без) ацетаминофена; пациенты 2-й группы – антигипертензивную терапию и ацетаминофен. Исходно и через 3 и 6 мес лечения оценивали изменение выраженности ОА по индексам WOMAC, Лекена, эффективность лечения врачом и пациентом по визуальной аналоговой шкале, кардиоваскулярную безопасность (во время первого и заключительного визитов) на основании изучения антитромбогенных свойств сосудистой стенки и жесткости артерий.Результаты. У всех пациентов, принимавших терафлекс на протяжении 6 мес, отмечен положительный эффект, выразившийся в существенном снижении индексов WOMAC, Лекена, уменьшении болевого синдрома и потребности в анальгетиках по сравнению как с исходным уровнем, так и с показателями у пациентов, получавших только ацетаминофен. Выявлено повышение фибринолитической активности сосудистой стенки на фоне терапии терафлексом. У пациентов с ОА и АГ, получавших антигипертензивную терапию и терафлекс, наблюдалось более выраженное снижение индекса аугментации и скорости пульсовой волны.Выводы. У пациентов 1-й группы не только уменьшались болевой синдром и потребность в приеме анальгетиков, но и не отмечено дестабилизации АГ. Наблюдались также уменьшение эндотелиальной дисфункции, выражавшееся в повышении фибринолитической активности сосудистой стенки, снижение брахиального и аортального индексов аугментации, скорости пульсовой волны

Torsional Magnetic Oscillations in Type I X-Ray Bursts

Thermonuclear burning on the surface of a neutron star causes the expansion of a thin outer layer of the star, $\Delta R(t)$. The layer rotates slower than the star due to angular momentum conservation. The shear between the star and the layer acts to twist the star's dipole magnetic field giving at first a trailing spiral field. The twist of the field acts in turn to `torque up' the layer increasing its specific angular momentum. As the layer cools and contracts, its excess specific angular momentum causes it to {\it rotate faster} than the star which gives a leading spiral magnetic field. The process repeats, giving rise to torsional oscillations. We derive equations for the angular velocity and magnetic field of the layer taking into account the diffusivity and viscosity which are probably due to turbulence. The magnetic field causes a nonuniformity of the star's photosphere (at the top of the heated layer), and this gives rise to the observed X-ray oscillations. The fact that the layer periodically rotates faster than the star means that the X-ray oscillation frequency may ``overshoot'' the star's rotation frequency. Comparison of the theory is made with observations of Chakrabarty et al. (2003) of an X-ray burst of SAX J1808.4-3658.Comment: 7 pages, 6 figures, accepted for publication in the Ap

Dissipationless Disk Accretion

We consider disk accretion resulting purely from the loss of angular momentum due to the outflow of plasma from a magnetized disk. In this limiting case, the dissipation due to the viscosity and finite electrical conductivity of the plasma can be neglected. We have obtained self-consistent, self-similar solutions for dissipationless disk accretion. Such accretion may result in the formation of objects whose bolometric luminosities are lower than the flux of kinetic energy in the ejected material.Comment: 17 pages, 6 figures, published in Astronomy Reports, Vol.49, No.1, 2005, p.57 (submitted September 13, 2003). Unfortunately, we did not upload the paper to astro-ph before, but since the topic is now of interest we feel that the paper would benefit the communit

Microevolution of tick-borne encephalitis virus in course of host alternation

AbstractTwo tick-borne encephalitis (TBE) virus variants were studied: mouse brain-adapted strain EK-328 and its derivate adapted to Hyalomma marginatum ticks. The tick-adapted virus exhibited small-plaque phenotype and slower replication in PEK cells, higher yield in ticks, decreased neuroinvasiveness in mice, increased binding to heparin-sepharose. A total of 15 nucleotide substitutions distinguished genomes of these variants, six substitutions resulted in protein sequence alterations, and two were in 5′NTR. Two amino acid substitutions in E protein were responsible for the observed phenotypic differences. Data obtained during reverse passaging of the tick-adapted virus in vivo and in vitro suggest that TBE virus exists as a heterogeneous population that contains virus variants most adapted to reproduction in either ticks or mammals. Host switch results in a change in the ratio of these variants in the population. Plaque purification of the tick-adapted virus resulted in the prompt emergence of new mutants with different virulence for mammals