109 research outputs found
Deux nouveau horizons a vertebres (Chondrichthyes-Elasmobranchii et osteichthyes actinopterygii) dans le toarcien belge et limitrophe (Lorraine) synthese stratigraphique et profils nouveaux
Two new vertebrates faunas (elasmobranches, actinopterygians, reptiles) from the belgian Toarcian are introduced. A stratigraphy review of the Lorraine Toarcian is proposed
Disused Jurassic regional stage from Belgium: Virtonian
An overview of the definition and history of the Virtonian is given with the argumentation for the abandonment of this disused regional stage
Disused Jurassic regional stage from Belgium: Virtonian
An overview of the definition and history of the Virtonian is given with the argumentation for the abandonment of this disused regional stage
A note on an early Jurassic ophiuroid from Rachecourt (Lorraine, Belgium)
A fairly well-preserved ophiuroid, collected from micaceous sandy argillites of the Messaney Formation (Domerian, late Pliensbachian) as exposed at Rachecourt (Gaume, Belgian Lorraine) is described and tentatively identified as Sinosura wolburgi (Hess, 1960). The rarity of complete ophiuroid fossils in Belgian Jurassic deposits and the poor fossil content of the Messaney Formation (bioelastic beds, crinoid columnals) warrant description of the present specimen
Skyrmion and Skyrme-Black holes in de Sitter spacetime
Numerical arguments are presented for the existence of regular and black hole
solutions of the Einstein-Skyrme equations with a positive cosmological
constant. These classical configurations approach asymptotically the de Sitter
spacetime. The main properties of the solutions and the differences with
respect to the asymptotically flat ones are discussed. It particular our
results suggest that, for a positive cosmological constant, the mass evaluated
as timelike infinity in infinite. Special emphasis is set to De Sitter black
holes Skyrmions which display two horizons.Comment: 11 pages, 4 figure
A new microvertebrate fauna from the Middle Hettangian (early Jurassic) of Fontenoille (Province of Luxembourg, south Belgium)
A Lower Jurassic horizon from Fontenoille yielding fossil fish remains can be dated to the Middle Hettangian Liasicus zone on the basis of the early belemnite Schwegleria and the ammonite Alsatites Iciqueus francus. Hybodontiform sharks are represented by Hybodus reticularis, Lissodus sp„ Polxacrodus sp, and Neoselachians by Synechodus paludinensis nov. sp. and Synechodus streitzi, nov. sp. Earlier reports of a scyliorhinid are not confirmed; teeth of similar morphology to scyliorhinids seem to be juvenile variants of 5. paludinensis. Chimaeriform remains include Squaloraja sp., the earliest occurrence of the genus. The Actinopterygian fauna is introduced, comprising a palaeonisciform cf. Ptxcholepis, a possible late perleidiform cf. Platysiagum, the dapediid semionotiforms Dapedium and cf. Tetragonolepis, the pycnodontiform Eomesodon, halecomorphs cf. Furidae or Ophiopsidae, pholidophoriforms and/or Leptolepididae, and actinistians. Lepidosaur remains are also present
Non Uniform Black Strings and Critical Dimensions in
We study the equations of black strings in spacetimes of arbitrary dimensions
with a negative cosmological constant and construct numerically non uniform
black strings solutions. Our results suggest the existence of a localised black
hole in asymptotically locally spacetime. We also present evidences for a
dependence of the critical dimension on the horizon radius.The critical
dimension represents the dimension where the order of the phase transition
between uniform and non uniform black string changes. Finally, we argue that
both, the regular asymptotically locally solution and black string
solutions with a very small horizon radius, present a negative tension. This
turns out to be an unexpected feature of the solutions.Comment: 13 pages, 5 figure
Charged-rotating black holes and black strings in higher dimensional Einstein-Maxwell theory with a positive cosmological constant
We present arguments for the existence of charged, rotating black holes in
dimensions, with with a positive cosmological constant.
These solutions posses both, a regular horizon and a cosmological horizon of
spherical topology and have equal-magnitude angular momenta. They approach
asymptotically the de Sitter spacetime background. The counterpart equations
for are investigated, by assuming that the fields are independant of
the extra dimension , leading to black strings solutions. These solutions
are regular at the event horizon. The asymptotic form of the metric is not the
de Sitter form and exhibit a naked singularity at finite proper distance.Comment: 21 pages, 9 figure
New stable phase of non uniform black strings in
We consider the non uniform black string equations in arbitrary number
of dimension in a perturbative approach up to order 2 and in a non
perturbative. We restrict the study in the perturbative approach to the
backreacting modes, since they provide the first relevant corrections on the
thermodynamical quantities of the solutions. We also present some preliminary
results in the construction of non-perturbative solutions, in particular, we
present a first part of the non uniform - uniform black string phase diagram.
Our results suggests the existence of a new stable phase for non uniform
black strings, namely long non uniform black string, with the extra direction
length of the order of the curvature.Comment: Results extended. 14 pages, 5 figure
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