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Search Results: 1 - 10 of 566 matches for " Mayara Krasinski;Goldenberg "
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Novos registros para a família Melastomataceae nos Estados do Paraná e Santa Catarina, Brasil
Meyer, Fabrício Schmitz;Meirelles, Julia;Caddah, Mayara Krasinski;Goldenberg, Renato;
Hoehnea , 2012, DOI: 10.1590/S2236-89062012000200011
Abstract: the genus henriettea dc. were recorded for the first time in santa catarina state, as well as four species of melastomataceae: henriettea glabra (vell.) penneys, michelangeli, judd & almeda, leandra tetraquetra (cham.) cogn., miconia racemifera (dc.) triana and miconia paniculata (dc.) naudin. miconia paniculata and salpinga margaritacea (naudin) triana are also recorded for the first time for paraná state, and the latter is confirmed for santa catarina state, since its occurrence was previosly recorded based in an old and flowerless collection. all these species have their distribution limits extended towards the south, reaching the paraná and santa catarina states. descriptions, illustrations and taxonomic comments for all these new records are provided.
Rotating dust solutions of Einstein's equations with 3-dimensional symmetry groups, Part 3: All Killing fields linearly independent of u^α and w^α
Andrzej Krasinski
Physics , 1997, DOI: 10.1063/1.532302
Abstract: This is the third and last part of a series of 3 papers. Using the same method and the same coordinates as in parts 1 and 2, rotating dust solutions of Einstein's equations are investigated that possess 3-dimensional symmetry groups, under the assumption that each of the Killing vectors is linearly independent of velocity $u^{\alpha}$ and rotation $w^{\alpha}$ at every point of the spacetime region under consideration. The Killing fields are found and the Killing equations are solved for the components of the metric tensor in every case that arises. No progress was made with the Einstein equations in any of the cases, and no previously known solutions were identified. A brief overview of literature on solutions with rotating sources is given.
The newest release of the Ortocartan set of programs for algebraic calculations in relativity
Andrzej Krasinski
Physics , 2000, DOI: 10.1023/A:1002028019791
Abstract: The program Ortocartan for algebraic calculations in relativity has just been implemented in the Codemist Standard Lisp and can now be used under the Windows 98 and Linux operating systems. The paper describes the new facilities and subprograms that have been implemented since the previous release in 1992. These are: the possibility to write the output as Latex input code and as Ortocartan's input code, the calculation of the Ellis evolution equations for the kinematic tensors of flow, the calculation of the curvature tensors from given (torsion-free) connection coefficients in a manifold of arbitrary dimension, the calculation of the lagrangian from a given metric by the Landau-Lifshitz method, the calculation of the Euler-Lagrange equations from a given lagrangian (only for sets of ordinary differential equations) and the calculation of first integrals of sets of ordinary differential equations of second order (the first integrals are assumed to be polynomials of second degree in the first derivatives of the functions).
Rotating dust solutions of Einstein's equations with 3-dimensional symmetry groups, Part 2: One Killing field spanned on u^α and w^α
Andrzej Krasinski
Physics , 1997, DOI: 10.1063/1.532336
Abstract: This is the second part of a series of 3 papers. Using the same method and the same coordinates as in part 1, rotating dust solutions of Einstein's equations are investigated that possess 3-dimensional symmetry groups, under the assumption that only one of the Killing fields is spanned on the fields of velocity $u^{\alpha}$ and rotation $w^{\alpha}$, while the other two define vectors that are linearly independent of $u^{\alpha}$ and $w^{\alpha}$ at every point of the spacetime region under consideration. The Killing fields are found and the Killing equations solved for the components of the metric tensor in every case that arises. The Einstein equations are simplified in a few cases, three (most probably) new solutions are found, and several classes of solutions known earlier are identified in the present scheme. They include those by Ozsv\'ath, Maitra, Ellis, King and Vishveshwara and Winicour. PACS numbers 04.20.-q, 04.20.Cv, 04.20.Jb, 04.40.+c
Rotating dust solutions of Einstein's equations with 3-dimensional symmetry groups; Part 1: Two Killing fields spanned on u^α and w^{α}
Andrzej Krasinski
Physics , 1997, DOI: 10.1063/1.532300
Abstract: For a rotating dust with a 3-dimensional symmetry group all possible metric forms can be classified and, within each class, explicitly written out. This is made possible by the formalism of Pleba\'nski based on the Darboux theorem. In the resulting coordinates, the Killing vector fields (if any exist) assume a special form. Each Killing vector field may be either spanned on the fields of velocity and rotation or linearly independent of them. By considering all such cases one arrives at the classification. With respect to the structures of the groups, this is just the Bianchi classification, but with all possible orientations of the orbits taken into account. In this paper, which is part 1 of a 3-part series, all solutions are considered for which two Killing fields are spanned on velocity and rotation. The solutions of Lanczos and G\"{o}del are identified as special cases, and their new invariant definitions are provided. In addition, a new invariant definition is given of the Ozsvath class III solution.
The join of algebraic curves
T. Krasinski
Mathematics , 2000,
Abstract: Let X,Y be algebraic curves in P^n over C. We give an effective description of the join J(X,Y)\in P^n of X and Y in terms of local parametrizations of X and Y.
Rotating Bianchi type V dust models generalizing the k = -1 Friedmann model
Andrzej Krasinski
Mathematics , 2000, DOI: 10.1063/1.1330197
Abstract: The Einstein equations for one of the hypersurface-homogeneous rotating dust models are investigated. It is a Bianchi type V model in which one of the Killing fields is spanned on velocity and rotation (case 1.2.2.2 in the classification scheme of the earlier papers). A first integral of the field equations is found, and with a special value of this integral coordinate transformations are used to eliminate two components of the metric. The k = -1 Friedmann model is shown to be contained among the solutions in the limit of zero rotation. The field equations for the simplified metric are reduced to 3 second-order ordinary differential equations that determine 3 metric components plus a first integral that algebraically determines the fourth component. First derivatives of the metric components are subject to a constraint (a second-degree polynomial with coefficients depending on the functions). It is shown that the set does not follow from a Lagrangian of the Hilbert type. The group of Lie point-symmetries of the set is found, it is two-dimensional noncommutative. Finally, a method of searching for first integrals (for sets of differential equations) that are polynomials of degree 1 or 2 in the first derivatives is applied. No such first integrals exist. The method is used to find a constraint (of degree 1 in first derivatives) that could be imposed on the metric, but it leads to a vacuum solution, and so is of no interest for cosmology.
Friedmann limits of rotating hypersurface-homogeneous dust models
Andrzej Krasinski
Mathematics , 2001, DOI: 10.1063/1.1378304
Abstract: The existence of Friedmann limits is systematically investigated for all the hypersurface-homogeneous rotating dust models, presented in previous papers by this author. Limiting transitions that involve a change of the Bianchi type are included. Except for stationary models that obviously do not allow it, the Friedmann limit expected for a given Bianchi type exists in all cases. Each of the 3 Friedmann models has parents in the rotating class; the k = +1 model has just one parent class, the other two each have several parent classes. The type IX class is the one investigated in 1951 by Goedel. For each model, the consecutive limits of zero rotation, zero tilt, zero shear and spatial isotropy are explicitly calculated.
Physical and Geometrical Interpretation of the epsilon <= 0 Szekeres Models
Charles Hellaby,Andrzej Krasinski
Physics , 2007, DOI: 10.1103/PhysRevD.77.023529
Abstract: We study the properties and behaviour of the quasi-pseudospherical and quasi-planar Szekeres models, obtain the regularity conditions, and analyse their consequences. The quantities associated with "radius" and "mass" in the quasi-spherical case must be understood in a different way for these cases. The models with pseudospherical foliation can have spatial maxima and minima, but no origins. The "mass" and "radius" functions may be one increasing and one decreasing without causing shell crossings. This case most naturally describes a snake-like, variable density void in a more gently varying inhomogeneous background, although regions that develop an overdensity are also possible. The Szekeres models with plane foliation can have neither spatial extrema nor origins, cannot be spatially flat, and they cannot have more inhomogeneity than the corresponding Ellis model, but a planar surface can be the boundary between regions of spherical and pseudospherical foliation.
Alternative Methods of Describing Structure Formation in the Lemaitre-Tolman Model
Charles Hellaby,Andrzej Krasinski
Physics , 2005, DOI: 10.1103/PhysRevD.73.023518
Abstract: We describe several new ways of specifying the behaviour of Lemaitre-Tolman (LT) models, in each case presenting the method for obtaining the LT arbitrary functions from the given data, and the conditions for existence of such solutions. In addition to our previously considered `boundary conditions', the new ones include: a simultaneous big bang, a homogeneous density or velocity distribution in the asymptotic future, a simultaneous big crunch, a simultaneous time of maximal expansion, a chosen density or velocity distribution in the asymptotic future, only growing or only decaying fluctuations. Since these conditions are combined in pairs to specify a particular model, this considerably increases the possible ways of designing LT models with desired properties.
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