Cuscuton kinks and branes

In this paper, we study a peculiar model for the scalar field. We add the cuscuton term in a standard model and investigate how this inclusion modifies the usual behavior of kinks. We find the first order equations and calculate the energy density and the total energy of the system. Also, we investigate the linear stability of the model, which is governed by a Sturm-Liouville eigenvalue equation that can be transformed in an equation of the Shcr\"odinger type. The model is also investigated in the braneworld scenario, where a first order formalism is also obtained and the linear stability is investigated.Comment: 21 pages, 9 figures; content added; to appear in NP

The Signature Triality of Majorana-Weyl Spacetimes

Higher dimensional Majorana-Weyl spacetimes present space-time dualities which are induced by the Spin(8) triality automorphisms. Different signature versions of theories such as 10-dimensional SYM's, superstrings, five-branes, F-theory, are shown to be interconnected via the S_3 permutation group. Bilinear and trilinear invariants under space-time triality are introduced and their possible relevance in building models possessing a space-versus-time exchange symmetry is discussed. Moreover the Cartan's ``vector/chiral spinor/antichiral spinor" triality of SO(8) and SO(4,4) is analyzed in detail and explicit formulas are produced in a Majorana-Weyl basis. This paper is the extended version of hep-th/9907148.Comment: 28 pages, LaTex. Extended version of hep-th/990714

Local Physical Coodinates from Symplectic Projector Method

The basic arguments underlying the symplectic projector method are presented. By this method, local free coordinates on the constrait surface can be obtained for a broader class of constrained systems. Some interesting examples are analyzed.Comment: 8 page

The Fertilization of Forage Grasses with Phosphorus in the Cerrado Area of Uberaba-MG, Brazil

Using an area of Cerrado at the EPAMIG Experimental Station in Uberaba - MG, it was studied the response of four forage grasses to phosphorus application. It was used the grasses: Andropogon gayanus, Brachiaria brizantha, Hyparrhenia rufa, and Panicum maximum. The phosphorus fertilizer used was a yoorin termophosphate and the doses were: 0, 50, 100, 150, and 200 kg/ha of P2O5. The experimental design was a randomized complete block with three replications. Each experimental unit measured 6x8m and the measured parameters were: dry matter production, protein production, percentage of dry matter, and protein, and the plant height at cutting time. The application of phosphorus increased dry matter production , crude protein production, and the plant height. Crude protein and dry matter contents were not influenced by the fertilization with phosphorus

Productivity of Grasses in a Pasture in the Cerrado Area of the Triangulo Mineiro

A grazing trial using guinea and coloniao (Panicum maximum), setaria (Setaria sphacelata), andropogon (Andropogon gayanus), and signalgrass (Brachiaria decumbens) was conducted during three grazing cycles: 1st cycle - Apr. 5, 1984 to Jul. 23, 1984; 2nd - Dec. 4, 1984 to Oct. 30, 1985 and 3rd - Jan. 16, 1986 to Jan. 15, 1987. It was also used with four stocking rates- T1= 0.8, T2= 1.0, T3= 1.2, and T4= 1.4 animal units/ha (AU/ha). In the 2nd period signalgrass was discarded because of poor condition of the pastures, and in the last grazing cycle only andropogon and setaria were used because the other grasses presented a very poor stand. LWG/ha varied from grass to grass, and according to the grazing period. Andropogon always allowed poor cattle performance. The other grasses did not present a great variation, except for the 1st period, which was a short period

Torsion and Gravitation: A new view

According to the teleparallel equivalent of general relativity, curvature and torsion are two equivalent ways of describing the same gravitational field. Despite equivalent, however, they act differently: whereas curvature yields a geometric description, in which the concept of gravitational force is absent, torsion acts as a true gravitational force, quite similar to the Lorentz force of electrodynamics. As a consequence, the right-hand side of a spinless-particle equation of motion (which would represent a gravitational force) is always zero in the geometric description, but not in the teleparallel case. This means essentially that the gravitational coupling prescription can be minimal only in the geometric case. Relying on this property, a new gravitational coupling prescription in the presence of curvature and torsion is proposed. It is constructed in such a way to preserve the equivalence between curvature and torsion, and its basic property is to be equivalent with the usual coupling prescription of general relativity. According to this view, no new physics is connected with torsion, which appears as a mere alternative to curvature in the description of gravitation. An application of this formulation to the equations of motion of both a spinless and a spinning particle is madeComment: To appear on IJMP