5,059 research outputs found
The Levi-Civita spacetime as a limiting case of the Gamma spacetime
It is shown that the Levi-Civita metric can be obtained from a family of the
Weyl metric, the Gamma metric, by taking the limit when the length of its
Newtonian image source tends to infinity. In this process a relationship
appears between two fundamental parameters of both metrics.Comment: LaTeX2e 17 page
The Levi-Civita spacetime
We consider two exact solutions of Einstein's field equations corresponding
to a cylinder of dust with net zero angular momentum. In one of the cases, the
dust distribution is homogeneous, whereas in the other, the angular velocity of
dust particles is constant [1]. For both solutions we studied the junction
conditions to the exterior static vacuum Levi-Civita spacetime. From this study
we find an upper limit for the energy density per unit length of the
source equal for the first case and for the second
one. Thus the homogeneous cluster provides another example [2] where the range
of is extended beyond the limit value previously found in
the literature [3,4]. Using the Cartan Scalars technics we show that the
Levi-Civita spacetime gets an extra symmetry for or
. We also find that the cluster of homogeneous dust has a superior
limit for its radius, depending on the constant volumetric energy density
Isolamento de proteínas Cyt de Bacillus thuringiensis subsp. israelensis por gradiente de sacarose.
xbitstream/item/68186/1/bol-37.pd
Determining factors in becoming a sustainable smart city: an empirical study in Europe
This paper aims firstly to identify differences and similarities between cities according to the activities which are necessary to become a smart city and secondly to identify relevant factors that could influence positions in the smart cities ranking. To achieve these goals, this study uses a quantitative analysis applied to 73 European cities to identify the factors that influence differences between smart cities. The results suggest the formation of clusters around European smart cities and also that cities located geographically in the west of Europe and with governance by women present higher levels in the European Smart Cities rankings.info:eu-repo/semantics/publishedVersio
Photoassociative ionization of Na inside a storage ring
Motivated by recent interest in low dimensional arrays of atoms, we
experimentally investigated the way cold collisional processes are affected by
the geometry of the considered atomic sample. More specifically, we studied the
case of photoassociative ionization (PAI) both in a storage ring where
collision is more unidirectional in character and in a trap with clear
undefinition of collision axis. First, creating a ring shaped trap (atomotron)
we investigated two-color PAI dependence with intensity and polarization of a
probing laser. The intensity dependence of the PAI rate was also measured in a
magneto-optical trap presenting equivalent temperature and density conditions.
Indeed, the results show that in the ring trap, the value of the PAI rate
constant is much lower and does not show evidences of saturation, unlike in the
case of the 3D-MOT. Cold atomic collisions in storage ring may represent new
possibilities for study.Comment: 5 pages, 5 figures; Accepted by Optics Communicatio
Electrophoretic characterization of total protein from the supernatant of Bacillus thuringiensis strains with different mortality effects on Spodoptera frugiperda larvae.
Mortality effect on the culture supernatant of five strains of Bacillus thuringiensis of the diet of Spodoptera frugiperda larvae.
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