16,431 research outputs found
Fractal basins of escape and the formation of spiral arms in a galactic potential with a bar
We investigate the dynamics in the close vicinity of and within the critical
area in a 2D effective galactic potential with a bar of Zotos. We have
calculated Poincar\'e surfaces of section and the basins of escape. In both the
Poincar\'e surfaces of section and the basins of escape we find numerical
evidence for the existence of a separatrix which hinders orbits from escaping
out of the bar region. We present numerical evidence for the similarity between
spiral arms of barred spiral galaxies and tidal tails of star clusters.Comment: 12 pages, 10 figures, accepted by MNRA
On the K-theoretic fundamental classes of Deligne-Lusztig varieties
In this paper we express the class of the structure sheaves of the closures
of Deligne--Lusztig varieties as explicit double Grothendieck polynomials in
the first Chern classes of appropriate line bundles on the ambient flag
variety. This is achieved by viewing such closures as degeneracy loci of
morphisms of vector bundles.Comment: 8 pages, minor change
Half-filled Hubbard Model on a Bethe lattice with next-nearest neighbor hopping
We study the interplay between N\'eel-antiferromagnetism and the paramagnetic
metal-insulator-transition (PMIT) on a Bethe lattice with nearest and
next-nearest eighbor hopping and . We concentrate in this paper on
the situation at half-filling. For the PMIT outgrows the
antiferromagnetic phase and shows a scenario similar to VO. In this
parameter regime we also observe a novel magnetic phase.Comment: 8 pages, 10 figure
A one-dimensional ultracold medium of extreme optical depth
We report on the preparation of a one-dimensional ultracold medium in a
hollow-core photonic crystal fiber, reaching an effective optical depth of
1000(150). We achieved this extreme optical depth by transferring atoms from a
magneto-optical trap into a far-detuned optical dipole trap inside the
hollow-core fiber, yielding up to 2.5(3)10 atoms inside the core
with a loading efficiency of . The preparation of an ultracold
medium of such huge optical depth paves the way towards new applications in
quantum optics and nonlinear optics
Issues Relevant to C-H Activation at Platinum(II): Comparative Studies between Cationic, Zwitterionic, and Neutral Platinum(II) Compounds in Benzene Solution
Cationic late metal systems are being highly scrutinized due to
their propensity to mediate so-called electrophilic C-H
activation reactions. This contribution compares the reactivity
of highly reactive cationic platinum(II) systems with
structurally related but neutral species. Our experimental
design exploits isostructural neutral and cationic complexes
supported by bis(phosphine) ligands amenable to mechanistic
examination in benzene solution. The data presented herein
collectively suggests that neutral platinum complexes can be
equally if not more reactive towards benzene than their
cationic counter-parts. Moreover, a number of unexpected
mechanistic distinctions between the two systems arise that
help to explain their respective reactivity
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