285 research outputs found
Existential questions in (relatively) hyperbolic groups {\it and} Finding relative hyperbolic structures
This arXived paper has two independant parts, that are improved and corrected
versions of different parts of a single paper once named "On equations in
relatively hyperbolic groups".
The first part is entitled "Existential questions in (relatively) hyperbolic
groups". We study there the existential theory of torsion free hyperbolic and
relatively hyperbolic groups, in particular those with virtually abelian
parabolic subgroups. We show that the satisfiability of systems of equations
and inequations is decidable in these groups.
In the second part, called "Finding relative hyperbolic structures", we
provide a general algorithm that recognizes the class of groups that are
hyperbolic relative to abelian subgroups.Comment: Two independant parts 23p + 9p, revised. To appear separately in
Israel J. Math, and Bull. London Math. Soc. respectivel
Hyperbolically embedded subgroups and rotating families in groups acting on hyperbolic spaces
We introduce and study the notions of hyperbolically embedded and very
rotating families of subgroups. The former notion can be thought of as a
generalization of the peripheral structure of a relatively hyperbolic group,
while the later one provides a natural framework for developing a geometric
version of small cancellation theory. Examples of such families naturally occur
in groups acting on hyperbolic spaces including hyperbolic and relatively
hyperbolic groups, mapping class groups, , and the Cremona group.
Other examples can be found among groups acting geometrically on
spaces, fundamental groups of graphs of groups, etc. We obtain a number of
general results about rotating families and hyperbolically embedded subgroups;
although our technique applies to a wide class of groups, it is capable of
producing new results even for well-studied particular classes. For instance,
we solve two open problems about mapping class groups, and obtain some results
which are new even for relatively hyperbolic groups.Comment: Revision, corrections and improvement of the expositio
Accidental parabolics and relatively hyperbolic groups
By constructing, in the relative case, objects analoguous to Rips and Sela's
canonical representatives, we prove that the set of images by morphisms without
accidental parabolic, of a finitely presented group in a relatively hyperbolic
group, is finite, up to conjugacy.Comment: Revision, 24 pages, 4 figure
Some integral inequalities on time scales
In this paper, some new integral inequalities on time scales are presented by
using elementarily analytic methods in calculus of time scales.Comment: 8 page
Non Insulin Dependent Diabetes in Sand Rat (Psammomys obesus) and Production of Collagen in Cultured Aortic Smooth Muscle Cells. Influence of Insulin
In this report, we have shown that the standard
laboratory diet administered to Psammomys obesus
(sand rat) from Beni Abbes in Algeria, induced a
non-insulin dependant diabetes, characterised by
increase of body weight (p<0.001) as well as
hyperinsulinemia, hyperglycemia and hypercholesterolemia.
In cultured aortic smooth muscle
cells (SMC) of sand rats, type I and type III collagen
biosynthesis and insulin effects, at low dose, on
these parameters were investigated. In all
experimental conditions of cultured SMC study, The
α chains of type I collagen were analysed by
immunoblotting in media and cells
6-Bromo-1-(1,2-propadienyl)-3-(2-propynyl)-1H-imidazo[4,5-b]pyridin-2(3H)-one
The reaction of propargyl bromide and 6-bromo-1,3-dihydroimidazo[4,5-b]pyridin-2-one in refluxing dimethylformamide yields the title compound, C12H8BrN3O, which features nitrogen-bound propadienyl and propynyl substituents. The imidazolopyridine fused ring is planar (r.m.s. deviation = 0.012 Å); the propadienyl chain is coplanar with the fused ring as it is conjugated with it, whereas the propynyl chain is not as the nitrogen-bound C atom is a methylene linkage. The acetylenic H atom is hydrogen bonded to the carbonyl O atom of an adjacent molecule, forming a helical chain runnning along the b axis
1,3-Dibenzyl-6-bromo-1H-imidazo[4,5-b]pyridin-2(3H)-one
The imidazopyridine fused-ring in the title compound, C20H16BrN3O, is planar (r.m.s. deviation = 0.011 Å). The phenyl rings of the benzyl substitutents twist away from the central five-membered ring in opposite directions; the rings are aligned at 61.3 (1) and 71.2 (1)° with respect to this ring
Observation of Collective-Emission-Induced Cooling inside an Optical Cavity
We report the observation of collective-emission-induced, velocity-dependent
light forces. One third of a falling sample containing 3 x 10^6 cesium atoms
illuminated by a horizontal standing wave is stopped by cooperatively emitting
light into a vertically oriented confocal resonator. We observe decelerations
up to 1500 m/s^2 and cooling to temperatures as low as 7 uK, well below the
free space Doppler limit. The measured forces substantially exceed those
predicted for a single two-level atom.Comment: 10 pages, 5 figure
- …