4,313 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
Impurities near an Antiferromagnetic-Singlet Quantum Critical Point
Heavy fermion systems, and other strongly correlated electron materials,
often exhibit a competition between antiferromagnetic (AF) and singlet ground
states. Using exact Quantum Monte Carlo (QMC) simulations, we examine the
effect of impurities in the vicinity of such AF- singlet quantum critical
points, through an appropriately defined impurity susceptibility, .
Our key finding is a connection, within a single calculational framework,
between AF domains induced on the singlet side of the transition, and the
behavior of the nuclear magnetic resonance (NMR) relaxation rate . We
show that local NMR measurements provide a diagnostic for the location of the
QCP which agrees remarkably well with the vanishing of the AF order parameter
and large values of . We connect our results with experiments on
Cd-doped CeCoIn
Earnings management and debt in private companies: The effect of economic adjustment programmes
Our study analyses the relationship between the level of earnings management and the debt of unlisted companies in two countries liable to economic adjustment programmes – Portugal and Ireland – between 2008 and 2016. We also analyse whether there are differences between both countries in what results are concerned. In a sample of 970 unlisted companies, and according the discretionary accruals, we find evidence of a positive relationship between the level of debt and the level of earnings management, thus concluding that the level of this relationship is different in each country. We also demonstrate that during the period of time in which the financial support occurred, there was mitigation in the relationship between the level of earnings management and indebtedness.info:eu-repo/semantics/acceptedVersio
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
Melhoramento genético de seringueira.
O genero Hevea e a tecnica de polinizacao controlada
- …