14 research outputs found
Motion of particles on a Four-Dimensional Asymptotically AdS Black Hole with Scalar Hair
Motivated by black hole solutions with matter fields outside their horizon,
we study the effect of these matter fields in the motion of massless and
massive particles. We consider as background a four-dimensional asymptotically
AdS black hole with scalar hair. The geodesics are studied numerically and we
discuss about the differences in the motion of particles between the
four-dimensional asymptotically AdS black holes with scalar hair and their
no-hair limit, that is, Schwarzschild AdS black holes. Mainly, we found that
there are bounded orbits like planetary orbits in this background. However, the
periods associated to circular orbits are modified by the presence of the
scalar hair. Besides, we found that some classical tests such as perihelion
precession, deflection of light and gravitational time delay have the standard
value of general relativity plus a correction term coming from the cosmological
constant and the scalar hair. Finally, we found a specific value of the
parameter associated to the scalar hair, in order to explain the discrepancy
between the theory and the observations, for the perihelion precession of
Mercury and light deflection.Comment: 20 pages and 9 figures. arXiv admin note: text overlap with
arXiv:1309.216
Motion and collision of particles near DST Black holes
We consider Deser-Sarioglu-Tekin (DST) black holes as background and we study
such the motion of massive particles as the collision of two spinning particles
in the vicinity of its horizon. New kinds of orbits are allowed for small
deviations of General Relativity, but the behavior of the collision is similar
to the one observed for General Relativity. Some observables like bending of
light and the perihelion precession are analyzed.Comment: 21 pages and 10 figures. New versio
Null geodesics in five-dimensional Reissner-Nordstr\"om anti-de Sitter black hole
The study of the motion of photons around massive bodies is one of the most
useful tools to know the geodesic structure associated with said gravitational
source. In the present work, different possible paths projected in an invariant
hyperplane are investigated, considering five-dimensional Reissner-Nordstr\"om
anti-de Sitter black hole. Also, we study some observational test such as the
bending of light and the Shapiro time delay effect. Mainly, we found that the
motion of photons follows the hippopede of Proclus geodesic, which is a new
type of trajectory of second kind, being the Lima\c{c}on of Pascal their
analogue geodesic in four-dimensional Reissner-Nordstr\"om anti-de Sitter black
hole.Comment: Version accepted for publication by EPJ
Evaluation of the efficacy of essential oils of Lavandula angustifolia and Eucalyptus globulus for the control of Varroa destructor in Apis mellifera: A randomised field study
Varroa destructor is the most harmful and widespread parasite that spreads disease in bees. Eucalyptus spp essential oils (EOs), has been shown to be effective against V. destructor. Additionally, Lavender spp EOs treatment, resulted in mite mortality rates of 95% to 97% of V. destructor. During the treatments, 20 mL of each oil or the placebo was distributed on two sheets of papier-mâché located on the frames of the brood chamber inside each hive. The miticidal effects of Lavandula angustifolia and Eucalyptus globulus EOs were analysed. Parasitic load and mite fall were evaluated under field conditions. The mean infestation rate obtained from each of three treatment groups at the beginning of the study was less than 3.6%. Then, the infestation rate increased gradually in each group until day 36. The infestation rates in the groups treated with L. angustifolia and E. globulus EOs were lower than those in the control by more than two percentage points and never exceeded 10%; the differences between the control group and the L. angustifolia group were statistically significant (p <0.05). Both EO treatments were applied in four doses, which produced a prolonged effect that lowered the rates of parasite birth and reinfestation. The L. angustifolia EO was effective; in that treatment, parasitic loads were maintained at levels lower than those in the control group starting at the second treatment dose due to the reproductive cycles of both species