308 research outputs found
Exact static solutions in four dimensional Einstein-Maxwell-Dilaton gravity
Classes of exact static solutions in four-dimensional
Einstein-Maxwell-Dilaton gravity are found. Besides of the well-known solutions
previously found in the literature, new solutions are presented.It's shown that
spherically symmetric solutions, except the case of charged dilaton black hole,
represent globally naked strong curvature singularities.Comment: 8 pages, late
The effect of different packaging materials on proteolysis, sensory scores and gross composition of tulum cheese
In this study, tulum cheese was manufactured using raw ewe’s milk and was ripened in goat’s skin and plastic bags. The effect of ripening materials (skin bag or plastic) on proteolysis was investigated during 120 days of ripening. In addition, sensory scores of the cheeses were assessed at the 90th and 120th days. The gross composition was also determined at the initial stage of ripening. The results showed that, some significant differences were noted between cheeses ripened in goat’s skin and plastic bags in terms of gross composition due to the porous structure of skin bag, which causes moisture loses during ripening. Significant differences were observed in proteolysis indices including water, 12% tricholoroacetic acid and 5% phosphotungstic acid-soluble nitrogen fractions among the cheese samples during ripening. Proteolysis levels were higher in tulum cheeses ripened in goat’s skin.Key words: Tulum cheese, packaging material, sensory analysis, ripening, proteolysis
Deformations of surfaces associated with integrable Gauss–Mainardi–Codazzi equations
Cataloged from PDF version of article.Using the formulation of the immersion of a two-dimensional surface into the three-dimensional Euclidean space proposed recently, a mapping from each symmetry of integrable equations to surfaces in ℝ3 can be established. We show that among these surfaces the sphere plays a unique role. Indeed, under the rigid SU(2) rotations all integrable equations are mapped to a sphere. Furthermore we prove that all compact surfaces generated by the infinitely many generalized symmetries of the sine-Gordon equation are homeomorphic to a sphere. We also find some new Weingarten surfaces arising from the deformations of the modified Kurteweg-de Vries and of the nonlinear Schrödinger equations. Surfaces can also be associated with the motion of curves. We study curve motions on a sphere and we identify a new integrable equation characterizing such a motion for a particular choice of the curve velocity. © 2000 American Institute of Physics
Korteweg-de Vries surfaces
Cataloged from PDF version of article.We consider 2-surfaces arising from the Korteweg-de Vries (KdV) hierarchy and the KdV equation. The surfaces corresponding to the KdV equation are in a three-dimensional Minkowski (M3) space. They contain a family of quadratic Weingarten and Willmore-like surfaces. We show that some KdV surfaces can be obtained from a variational principle where the Lagrange function is a polynomial function of the Gaussian and mean curvatures. We also give a method for constructing the surfaces explicitly, i.e., finding their parameterizations or finding their position vectors.© 2013 Elsevier Ltd. All rights reser
Colliding Plane Waves in String Theory
We construct colliding plane wave solutions in higher dimensional gravity
theory with dilaton and higher form flux, which appears naturally in the low
energy theory of string theory. Especially, the role of the junction condition
in constructing the solutions is emphasized. Our results not only include the
previously known CPW solutions, but also provide a wide class of new solutions
that is not known in the literature before. We find that late time curvature
singularity is always developed for the solutions we obtained in this paper.
This supports the generalized version of Tipler's theorem in higher dimensional
supergravity.Comment: latex, 25 pages, 1 figur
Type IIB Colliding Plane Waves
Four-dimensional colliding plane wave (CPW) solutions have played an
important role in understanding the classical non-linearities of Einstein's
equations. In this note, we investigate CPW solutions in --dimensional
Einstein gravity with a -form flux. By using an isomorphism with the
four-dimensional problem, we construct exact solutions analogous to the
Szekeres vacuum solution in four dimensions. The higher-dimensional versions of
the Khan-Penrose and Bell-Szekeres CPW solutions are studied perturbatively in
the vicinity of the light-cone. We find that under small perturbations, a
curvature singularity is generically produced, leading to both space-like and
time-like singularities. For , our results pertain to the collision of two
ten-dimensional type IIB Blau - Figueroa o'Farrill - Hull - Papadopoulos plane
waves.Comment: 20+10 pages, 2 figures, uses JHEP3.cls; v2: refs [3,10,22] corrected,
remark added below (3.9) on inexistence of conformally flat CPW in our
ansatz, final version to appear in JHE
All stationary axi-symmetric local solutions of topologically massive gravity
We classify all stationary axi-symmetric solutions of topologically massive
gravity into Einstein, Schr\"odinger, warped and generic solutions. We
construct explicitly all local solutions in the first three sectors and present
an algorithm for the numerical construction of all local solutions in the
generic sector. The only input for this algorithm is the value of one constant
of motion if the solution has an analytic centre, and three constants of motion
otherwise. We present several examples, including soliton solutions that
asymptote to warped AdS.Comment: 42 pages, 9 figures. v2: Changed potentially confusing labelling of
one sector, added references. v3: Minor changes, matches published versio
Thin static charged dust Majumdar-Papapetrou shells with high symmetry in D >= 4
We present a systematical study of static D >= 4 space-times of high symmetry
with the matter source being a thin charged dust hypersurface shell. The shell
manifold is assumed to have the following structure S_(beta) X R^(D-2-beta),
beta (in the interval ) is dimension of a sphere S_(beta). In case
of (beta) = 0, we assume that there are two parallel hyper-plane shells instead
of only one. The space-time has Majumdar-Papapetrou form and it inherits the
symmetries of the shell manifold - it is invariant under both rotations of the
S_(beta) and translations along R^(D-2-beta). We find a general solution to the
Einstein-Maxwell equations with a given shell. Then, we examine some flat
interior solutions with special attention paid to D = 4. A connection to D = 4
non-relativistic theory is pointed out. We also comment on a straightforward
generalisation to the case of Kastor-Traschen space-time, i.e. adding a
non-negative cosmological constant to the charged dust matter source.Comment: Accepted in Int. J. Theor. Phy
Behaviour of Magnetic Tubes in Neutron Star's Interior
It is found from Maxwell's equations that the magnetic field lines are good
analogues of relativistic strings. It is shown that the super-conducting
current in the neutron star's interior causes local rotation of magnetic flux
tubes carrying quantized flux.Comment: 6 pages, no figure
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