91 research outputs found

    Vacuum Einstein spaces with axial symmetry

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    Four classes of solutions are found to the equations Rαβ=-2σ;α σ;β and gαβ σ;αβ=0 in three-dimensional space with metric gαβdxαdxβ and signature (+ --), equivalent to the Einstein equations Rij=0 in a vacuum for the metric {Mathematical expression}. The metric ds2 assumes axial symmetry and symmetry with respect to the reflection {Mathematical expression}. © 1977 Plenum Publishing Corporation

    Covariant spinor derivative associated with arbitrary linear connectedness

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    A covariant spinor derivative is constructed in arbitrary reference frames and also in coordinates, with specified arbitrary linear connectedness. © 1999 Kluwer Academic/Plenum Publishers

    Covariant construction of the symmetric energy-momentum tensor of vector and spinor fields in an orthogonal frame of reference

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    A covariant method is devised to construct the symmetric energy-momentum tensor for vector fields in an orthogonal frame of reference. The method is then used to construct the symmetric energy-momentum tensor for spinor fields. © 1997 Plenum Publishing Corporation

    Advancing models of best practice in academic governance and management in higher education institutions in Kazakhstan

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    This is a collaborative research project of Nazarbayev University Graduate School of Education (NUGSE) in partnership with the Graduate School of Education of University of Pennsylvania (PennGSE). The Project aims at studying how academic leaders at public and private institutions in Kazakhstan are preparing for greater institutional autonomy and encouraging innovation [1]

    Space-times admitting a three-parameter similarity group

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    Spacetimes admitting a similarity group are considered. Amongst them, special attention is given to the 3-parameter ones. A classification of such spacetimes is given based on the Bianchi type of the similarity group H3H_3, and the general form of the metric is provided in each case assuming the orbits are non-null.Comment: Latex 17 pages. Error corrected in Class. Quant. Grav. 14(1997)1183-1205, gr-qc/960706

    Comparison between SiN x :H and hydrogen passivation of electromagnetically casted multicrystalline silicon material

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    International audienceThis work intends to compare two different passivation methods for electromagnetically continuous pulling silicon (EMCP): remote plasma hydrogenation and remote plasma enhanced CVD of SiN followed by high-temperature sintering. All experiments are carried out on textured and non-textured EMCP samples from the same ingot. To check the effect of high-temperature diffusion on EMCP, a n +-emitter is formed on one group of the samples using POCl 3 diffusion. Passivation capabilities of both techniques are checked using measurements of minority carrier lifetime by means of microwave photoconductance decay mapping. Solar cells are made to compare lifetime measurement with cell parameters.

    Hiatal hernia surgery: laparoscopic versus robotic approach?

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    Aim. Evaluate the advantages and disadvantages of laparoscopic and robot-assisted anti-reflux operations.General findings. Reflux esophagitis in the association with hiatal hernia on the third place in the structure of gastroenterological diseases. The development of minimally invasive surgical technologies has led to an increase in the number of laparoscopic and robot-assisted anti-reflux operations. The literature review includes 12 studies, the results of which were published from 2002 to 2020, with a total number of patients 1633. In most of them, when comparing laparoscopic and robot-assisted anti-reflux operations, the advantages of one or another technique were not revealed. In some studies, the high cost and duration of the operation were noted when using the da Vinci robotic surgical complex. Other studies have reported possible improvements in the treatment outcomes of patients with large or recurrent hiatal hernias due to the high precision of movement and improved visualization characteristic of therobot-assisted surgeries.Conclusion. It is necessary to conduct more researches on this problem to develop indications for the choice of a particular surgical approach, as well as to create a single transparent algorithm for the surgical treatment of patients with reflux esophagitis and hiatal hernia

    Symmetries of Bianchi I space-times

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    All diagonal proper Bianchi I space-times are determined which admit certain important symmetries. It is shown that for Homotheties, Conformal motions and Kinematic Self-Similarities the resulting space-times are defined explicitly in terms of a set of parameters whereas Affine Collineations, Ricci Collineations and Curvature Collineations, if they are admitted, they determine the metric modulo certain algebraic conditions. In all cases the symmetry vectors are explicitly computed. The physical and the geometrical consequences of the results are discussed and a new anisitropic fluid, physically valid solution which admits a proper conformal Killing vector, is given.Comment: 19 pages, LaTex, Accepted for publication in Journal of Mathematical Physic

    DIAGNOSTIC REPORT

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    The final report on the first phase (2013) of the “Development of the strategic directions for education reform in Kazakh- stan for 2015-2020” project was implemented by the Graduate School of Education at Nazarbayev University on behalf of the Ministry of Education and Science of the Republic of Kazakhstan. The purpose of this research is to conduct a diagnosis of the education system of the Republic of Kazakhstan in order to identify the strengths and weaknesses of the educational system and the subsequent identification of areas for further modernization at each level

    DIAGNOSTIC REPORT

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    The final report on the first phase (2013) of the “Development of the strategic directions for education reform in Kazakh- stan for 2015-2020” project was implemented by the Graduate School of Education at Nazarbayev University on behalf of the Ministry of Education and Science of the Republic of Kazakhstan. The purpose of this research is to conduct a diagnosis of the education system of the Republic of Kazakhstan in order to identify the strengths and weaknesses of the educational system and the subsequent identification of areas for further modernization at each level
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