280 research outputs found
Dynamics of continued fractions and kneading sequences of unimodal maps
In this paper we construct a correspondence between the parameter spaces of
two families of one-dimensional dynamical systems, the alpha-continued fraction
transformations T_alpha and unimodal maps. This correspondence identifies
bifurcation parameters in the two families, and allows one to transfer
topological and metric properties from one setting to the other. As an
application, we recover results about the real slice of the Mandelbrot set, and
the set of univoque numbers.Comment: 21 pages, 3 figures. New section added with additional results and
applications. Figures and references added. Introduction rearrange
Normal fault earthquakes or graviquakes
Earthquakes are dissipation of energy throughout elastic waves. Canonically is the elastic energy
accumulated during the interseismic period. However, in crustal extensional settings, gravity is
the main energy source for hangingwall fault collapsing. Gravitational potential is about 100 times
larger than the observed magnitude, far more than enough to explain the earthquake. Therefore,
normal faults have a different mechanism of energy accumulation and dissipation (graviquakes) with
respect to other tectonic settings (strike-slip and contractional), where elastic energy allows motion
even against gravity. The bigger the involved volume, the larger is their magnitude. The steeper the
normal fault, the larger is the vertical displacement and the larger is the seismic energy released.
Normal faults activate preferentially at about 60° but they can be shallower in low friction rocks. In
low static friction rocks, the fault may partly creep dissipating gravitational energy without releasing
great amount of seismic energy. The maximum volume involved by graviquakes is smaller than the
other tectonic settings, being the activated fault at most about three times the hypocentre depth,
explaining their higher b-value and the lower magnitude of the largest recorded events. Having
different phenomenology, graviquakes show peculiar precursor
There is only one KAM curve
International audienceWe consider the standard family of area-preserving twist maps of the annulus and the corresponding KAM curves. Addressing a question raised by Kolmogorov, we show that, instead of viewing these invariant curves as separate objects, each of which having its own Diophantine frequency, one can encode them in a single function of the frequency which is naturally defined in a complex domain containing the real Diophantine frequencies and which is monogenic in the sense of Borel; this implies a remarkable property of quasianalyticity, a form of uniqueness of the monogenic continuation, although real frequencies constitute a natural boundary for the analytic continuation from the Weierstrass point of view because of the density of the resonances
Tanaka-Ito -continued fractions and matching
Two closely related families of -continued fractions were
introduced in 1981: by Nakada on the one hand, by Tanaka and Ito on the other
hand. The behavior of the entropy as a function of the parameter has
been studied extensively for Nakada's family, and several of the results have
been obtained exploiting an algebraic feature called matching. In this article
we show that matching occurs also for Tanaka-Ito -continued
fractions, and that the parameter space is almost completely covered by
matching intervals. Indeed, the set of parameters for which the matching
condition does not hold, called bifurcation set, is a zero measure set (even if
it has full Hausdorff dimension). This property is also shared by Nakada's
-continued fractions, and yet there also are some substantial
differences: not only does the bifurcation set for Tanaka-Ito continued
fractions contain infinitely many rational values, it also contains numbers
with unbounded partial quotients
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