605 research outputs found

    Proses Berpikir Kreatif Siswa Tipe Sekuensial Abstrak Dan Acak Abstrak Pada Pemecahan Masalah Biologi

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    The aim of the research is to describe the creative thinking process of abstract sequential and abstract random type-students in solving biological problem. The research conducted on two subjects that had differences in the type of the thinking that is abstract sequential type-student (STBSA) and abstract random type-student (STBAA) at Attaufiq Senior High School Jambi city. The data were selected according to the purpose of research. The data was collected by interviewing and modified think aloud method. Data was analyzed by process of creative thinking frame work based on Polya's problem solving steps. The over all results of the study concluded that the process of STBSA's creative thinking conducted sequentially from the first stage to the last stage. The data which obtained according to problem-solving strategies and the steps in solving problems. The indicators of creativity are notified in the form of fluency, flexibility, originality, and the detail of biological solving problems. While STBAA, the steps of creative thinking process is done randomly and not sequentially. The results of the problem solving which conducted is not be conviced because STBAA used more insight, imagination and logic. Then, in terms of creativity, the flexibility of STBAA is not appropriate to the indicator to solve problems because only applying one method of complishment, doesn't have capability to produce a variety of ideas to implement the problem solving and not able to present a concept in different ways during biological problems solving. STBSA precisely solves the problem exactly, because it believes in the results of the thinking, as well as maintaining the criticality in the process of biological solving problems. While STBAA is less precise in solving problems due to the less of the self-confidence, less critical and contented easily in the process of solving biological problems

    Integrable Systems in Stringy Gravity

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    Static axisymmetric Einstein-Maxwell-Dilaton and stationary axisymmetric Einstein-Maxwell-Dilaton-Axion (EMDA) theories in four space-time dimensions are shown to be integrable by means of the inverse scattering transform method. The proof is based on the coset-space representation of the 4-dim theory in a space-time admitting a Killing vector field. Hidden symmetry group of the four-dimensional EMDA theory, unifying T and S string dualities, is shown to be Sp(2, R) acting transitively on the coset Sp(2, R)/U(2). In the case of two-parameter Abelian space-time isometry group, the hidden symmetry is the corresponding infinite-dimensional group of the Geroch-Kinnersley-Chitre type.Comment: 8 pages, LATEX, MSU-DTP-94/21, October 9

    On 2D2D quantum gravity coupled to a \s-model

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    This contribution is a review of the method of isomonodromic quantization of dimensionally reduced gravity. Our approach is based on the complete separation of variables in the isomonodromic sector of the model and the related ``two-time" Hamiltonian structure. This allows an exact quantization in the spirit of the scheme developed in the framework of integrable systems. Possible ways to identify a quantum state corresponding to the Kerr black hole are discussed. In addition, we briefly describe the relation of this model with Chern Simons theory.Comment: 9 pages, LaTeX style espcrc2, to appear in Proceedings of 29th International Symposium Ahrenshoop, Buckow, 199

    Binary black hole spacetimes with a helical Killing vector

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    Binary black hole spacetimes with a helical Killing vector, which are discussed as an approximation for the early stage of a binary system, are studied in a projection formalism. In this setting the four dimensional Einstein equations are equivalent to a three dimensional gravitational theory with a SL(2,C)/SO(1,1)SL(2,\mathbb{C})/SO(1,1) sigma model as the material source. The sigma model is determined by a complex Ernst equation. 2+1 decompositions of the 3-metric are used to establish the field equations on the orbit space of the Killing vector. The two Killing horizons of spherical topology which characterize the black holes, the cylinder of light where the Killing vector changes from timelike to spacelike, and infinity are singular points of the equations. The horizon and the light cylinder are shown to be regular singularities, i.e. the metric functions can be expanded in a formal power series in the vicinity. The behavior of the metric at spatial infinity is studied in terms of formal series solutions to the linearized Einstein equations. It is shown that the spacetime is not asymptotically flat in the strong sense to have a smooth null infinity under the assumption that the metric tends asymptotically to the Minkowski metric. In this case the metric functions have an oscillatory behavior in the radial coordinate in a non-axisymmetric setting, the asymptotic multipoles are not defined. The asymptotic behavior of the Weyl tensor near infinity shows that there is no smooth null infinity.Comment: to be published in Phys. Rev. D, minor correction

    The Ernst Equation on a Riemann Surface

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    The Ernst equation is formulated on an arbitrary Riemann surface. Analytically, the problem reduces to finding solutions of the ordinary Ernst equation which are periodic along the symmetry axis. The family of (punctured) Riemann surfaces admitting a non-trivial Ernst field constitutes a ``partially discretized'' subspace of the usual moduli space. The method allows us to construct new exact solutions of Einstein's equations in vacuo with non-trivial topology, such that different ``universes'', each of which may have several black holes on its symmetry axis, are connected through necks bounded by cosmic strings. We show how the extra topological degrees of freedom may lead to an extension of the Geroch group and discuss possible applications to string theory.Comment: 22 page

    Gravitational fields as generalized string models

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    We show that Einstein's main equations for stationary axisymmetric fields in vacuum are equivalent to the motion equations for bosonic strings moving on a special nonflat background. This new representation is based on the analysis of generalized harmonic maps in which the metric of the target space explicitly depends on the parametrization of the base space. It is shown that this representation is valid for any gravitational field which possesses two commuting Killing vector fields. We introduce the concept of dimensional extension which allows us to consider this type of gravitational fields as strings embedded in D-dimensional nonflat backgrounds, even in the limiting case where the Killing vector fields are hypersurface orthogonal.Comment: latex, 25 page

    Infinite-Dimensional Symmetries of Two-Dimensional Coset Models

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    It has long been appreciated that the toroidal reduction of any gravity or supergravity to two dimensions gives rise to a scalar coset theory exhibiting an infinite-dimensional global symmetry. This symmetry is an extension of the finite-dimensional symmetry G in three dimensions, after performing a further circle reduction. There has not been universal agreement as to exactly what the extended symmetry algebra is, with different arguments seemingly concluding either that it is G^\hat G, the affine Kac-Moody extension of G, or else a subalgebra thereof. Exceptional in the literature for its explicit and transparent exposition is the extremely lucid discussion by Schwarz, which we take as our starting point for studying the simpler situation of two-dimensional flat-space sigma models, which nonetheless capture all the essential details. We arrive at the conclusion that the full symmetry is described by the Kac-Moody algebra G, although truncations to subalgebras, such as the one obtained by Schwarz, can be considered too. We then consider the explicit example of the SL(2,R)/O(2) coset, and relate Schwarz's approach to an earlier discussion that goes back to the work of Geroch.Comment: Typos corrected, some reorganisation; 36 page

    Stationary axisymmetric solutions of five dimensional gravity

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    We consider stationary axisymmetric solutions of general relativity that asymptote to five dimensional Minkowski space. It is known that this system has a hidden SL(3,R) symmetry. We identify an SO(2,1) subgroup of this symmetry group that preserves the asymptotic boundary conditions. We show that the action of this subgroup on a static solution generates a one-parameter family of stationary solutions carrying angular momentum. We conjecture that by repeated applications of this procedure one can generate all stationary axisymmetric solutions starting from static ones. As an example, we derive the Myers-Perry black hole starting from the Schwarzschild solution in five dimensions.Comment: 31 pages, LaTeX; references adde

    Regular solutions to higher order curvature Einstein--Yang-Mills systems in higher dimensions

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    We study regular, static, spherically symmetric solutions of Yang-Mills theories employing higher order invariants of the field strength coupled to gravity in dd dimensions. We consider models with only two such invariants characterised by integers pp and qq. These models depend on one dimensionless parameter α\alpha leading to one-parameter families of regular solutions, obtainable by numerical solution of the corresponding boundary value problem. Much emphasis is put on an analytical understanding of the numerical results.Comment: 34 pages, 12 figure

    Properties of global monopoles with an event horizon

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    We investigate the properties of global monopoles with an event horizon. We find that there is an unstable circular orbit even if a particle does not have an angular momentum when the core mass is negative. We also obtain the asymptotic form of solutions when the event horizon is much larger than the core radius of the monopole, and discuss if they could be a model of galactic halos.Comment: 5 pages, 7 figure
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