Modification of structural and transport properties in epitaxial YBa2_2CU3_3Ox_x films by pulsed laser irradiation

Pulsed (~20 ns) laser effects in epitaxial YBa$_2$CU$_3$O$_x$/SrTiO$_3$ thin films were investigated, using RBS/channeling for compositional and structural characterization and 4-point technique for electrical measurements. It was found that laser pulse melting and following quenching lead to a transition from a single-crystalline to a polycrystalline state in films. The formation of grain boundaries causes a room temperature electrical resistivity increase by a factor 10-40, depending on the initial film properties and on the irradiation conditions. Unlike corpuscular (ions, neutrons) irradiation, the laser pulse induced structural damage did not lead to the disappearance of HTS, which persisted up to the highest laser fluences used. It was found, that a thermal model can consistently describe the fluence dependence of disorder, depth of surface relief and helps, with a simple two-layer model, in understanding of fluence dependence of room temperature resistivity in a relatively thick film.Les effects de pulses laser (~20 ns) sur des films minces épitaxiés d'YBa$_2$Cu$_3$O$_x$/SrTiO$_3$ ont été étudiés par rétrodiffusion Rutherford et canalisation afin de caractériser leur composition et leur structure et à l'aide de la technique des 4 points pour les mesures électriques. On a trouvé que la fusion par pulse laser suivie par une trempe entraîne une transition d'un film monocristallin vers un film polycristallin. La formation de joints de grains s'accompagne d'une augmentation d'un facteur 10-40, de la résistivité électrique à température ambiante, dépendante des propriétés initiales du film et des conditions d'irradiation. Contrairement à l'irradiation corpusculaire (ions, neutrons) l'endommagement produit par la pulse laser n'entraîne pas la disparition de la superconductivité à haute température (HTS), qui persiste jusqu'aux plus hautes doses utilisées. On a trouvé qu'un modèle thermique peut décrire de façon consistante, la profondeur de la rugosité de surface et en considérant un modèle simple à deux couches on peut comprendre la dépendance de la dose sur la résistivité à température ambiante pour des films relativement épais

Accuracy estimation of the technique for reconstructing the spacecraft attitude motion by measurements of its angular rate and Earth magnetic field strength

Abstract: The reconstruction technique is based on processing the measurements of two vectors: the spacecraft angular rate and the strength of the Earth magnetic field. The processing technique uses kinematical equations of the attitude motion of a rigid body. In its framework, the measurement data of both types, collected on a time interval, are processed jointly. The angular rate data are smoothed by suitable functions and those functions are substituted in kinematical equations for components of the quaternion, which defines a transformation of the spacecraft coupled coordinate system to inertial one. The equations obtained present the kinematical model of a spacecraft attitude motion. The solution of the equations, which approximates the real motion, is found by the least squares method from the condition of the best agreement between measurement and calculation data of the magnetic strength. The accuracy of the technique was investigated by processing measurements obtained on board Service Module of ISS. The reconstruction of ISS attitude motion was compared with telemetry data of its real motion. The errors of reconstruction of the motion in orbital orientation did not exceed 0.6°, the errors of reconstruction of rotations did not exceed 1.2°.Note: Research direction:Theoretical and applied problems of mechanic

Reconstruction of spacecraft Progress attitude motion in single axis solar orientation mode by measurements of current from solar arrays

Abstract: We reconstructed the uncontrolled attitude motion of the cargo spacecraft Progress M-24M, M-25M, MC-05 и MC-06 in the single-axis solar orientation mode (so-called solar rotation). At the beginning of the oriented motion, the spacecraft rotated around the normal to solar batteries with angular rate 2.2 deg./s and the normal was directed to the Sun. The oriented motion lasted for a few orbit revolutions. The reconstruction was made using measurements of the electric current from spacecraft solar arrays. The measurement data, collected in a time interval about a few tens of minutes, were processed simultaneously by statistical methods and integration of the spacecraft attitude motion equations. As a result, the spacecraft attitude motion was reconstructed relative to the direction Earth – Sun. The investigation of the current specter showed the possibility of this way of motion reconstruction using current measurements, which were seemed to be not informative for this purpose.Note: Research direction:Theoretical and applied problems of mechanic

Non-disjunction of chromosome 21, alphoid DNA variation, and sociogenetic features of Down syndrome

The analysis of non-disjunction of chromosome 21 and alphoid DNA variation by using cytogenetic and molecular cytogenetic techniques (quantitative fluorescence in situ hybridization) in 74 nuclear families was performed. The establishment of possible correlation between alphoid DNA variation, parental age, environmental effects, and non-disjunction of chromosome 21 was made. The efficiency of techniques applied was found to be 92 % (68 from 74 cases). Maternal non-disjunction was found in 58 cases (86 %) and paternal non-disjunction — in 7 cases (10 %). Post-zygotic mitotic non-disjunction was determined in 2 cases (3 %) and one case was associated with Robertsonian translocation 46,XX,der(21;21)(q10;q10),+21. Maternal meiosis I errors were found in 43 cases (64 %) and maternal meiosis II errors — in 15 cases (22 %). Paternal meiosis I errors occurred in 2 cases (3 %) and paternal meiosis I errors — in 5 cases (7 %). The lack of the correlation between alphoid DNA variation and non-disjunction of chromosome 21 was established. Sociogenetic analysis revealed the association of intensive drug therapy of infectious diseases during the periconceptual period and maternal meiotic non-disjunction of chromosome 21. The correlation between non-disjunction of chromosome 21 and increased parental age as well as exposure to irradiation, alcohol, tobacco, mutagenic substances was not found. The possible relevance of data obtained to the subsequent studies of chromosome 21 non-disjunction is discussed.Проведен анализ нерасхождения хромосомы 21 и вариации альфоидной ДНК в 74 ядерных семьях с детьми, страдающими синдромом Дауна, с помощью цитогенетических и молекулярно-цитогенетических (количественная флюоресцентная гибидизация in situ) методов. Помимо этого, был также проведен анализ корреляции между вариацией альфоидной ДНК, возрастом родителей, факторами окружающей среды и нерасхождением хромосомы 21. Эффективность использованных методов составила 92 % (68 из 74 случаев). Материнское нерасхождение было обнаружено в 58 случаях (86 %), отцовское — в 7 случаях (10 %). Постзиготическое митотическое нерасхождение было определено в 2 случаях (3 %) и в одном случае — робертсоновская транслокация 46,XX,der(21;21)(q10;q10),+21. Ошибки в материнском мейозе I были обнаружены в 43 случаях (64 %), в материнском мейозе II — в 15 случаях (22 %). Ошибки в отцовском мейозе I были определены в 2 случаях (2 %), в отцовском мейозе II — в 5 случаях (7 %). Было установлено отсутствие корреляции между вариацией альфоидной ДНК и нерасхождением хромосомы 21. Социогенетический анализ показал наличие корреляции между интенсивной лекарственной терапией инфекционных заболеваний в периконцепционном периоде и нерасхождением хромосомы 21 в материнском мейозе. Показано также, что нерасхождение хромосомы 21 нельзя определить достоверно связанным с большим возрастом родителей, воздействием радиации, употреблением алкоголя, курением табака, а также воздействием химических соединений с мутагенным эффектом. Обсуждается значимость полученных результатов для последующих исследований нерасхождения хромосомы 21

Research of vibrations of structure elements of the space station on video information

Abstract: Video information about vibrations of elements of ISS structure allows to establish quantitative characteristics of these vibrations. Such characteristics are found as a result of processing of time series obtained by digitizing of video film shots. Digital data are vertical and horizontal coordinates, expressed in pixels, of some points on a station structure element in a shot. Processing of the time series allows evaluating the real time dependence of the coordinates. This dependence in common has an oscillation character and can be presented by the sum of eventual number of simple harmonics, their amplitudes and frequencies being determined by means of spectral analysis.Note: Research direction:Theoretical and applied problems of mechanic