605 research outputs found
Proses Berpikir Kreatif Siswa Tipe Sekuensial Abstrak Dan Acak Abstrak Pada Pemecahan Masalah Biologi
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
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 quantum gravity coupled to a \s-model
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
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 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
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
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
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 , 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
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
We study regular, static, spherically symmetric solutions of Yang-Mills
theories employing higher order invariants of the field strength coupled to
gravity in dimensions. We consider models with only two such invariants
characterised by integers and . These models depend on one dimensionless
parameter 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
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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