14,603 research outputs found
Extreme Value Theory for Piecewise Contracting Maps with Randomly Applied Stochastic Perturbations
We consider globally invertible and piecewise contracting maps in higher
dimensions and we perturb them with a particular kind of noise introduced by
Lasota and Mackey. We got random transformations which are given by a
stationary process: in this framework we develop an extreme value theory for a
few classes of observables and we show how to get the (usual) limiting
distributions together with an extremal index depending on the strength of the
noise.Comment: 16 pages. arXiv admin note: text overlap with arXiv:1407.041
Statistical stability and limit laws for Rovella maps
We consider the family of one-dimensional maps arising from the contracting
Lorenz attractors studied by Rovella. Benedicks-Carleson techniques were used
by Rovella to prove that there is a one-parameter family of maps whose
derivatives along their critical orbits increase exponentially fast and the
critical orbits have slow recurrent to the critical point. Metzger proved that
these maps have a unique absolutely continuous ergodic invariant probability
measure (SRB measure).
Here we use the technique developed by Freitas and show that the tail set
(the set of points which at a given time have not achieved either the
exponential growth of derivative or the slow recurrence) decays exponentially
fast as time passes. As a consequence, we obtain the continuous variation of
the densities of the SRB measures and associated metric entropies with the
parameter. Our main result also implies some statistical properties for these
maps.Comment: 1 figur
A Random Multifractal Tilling
We develop a multifractal random tilling that fills the square. The
multifractal is formed by an arrangement of rectangular blocks of different
sizes, areas and number of neighbors. The overall feature of the tilling is an
heterogeneous and anisotropic random self-affine object. The multifractal is
constructed by an algorithm that makes successive sections of the square. At
each -step there is a random choice of a parameter related to the
section ratio. For the case of random choice between and we
find analytically the full spectrum of fractal dimensions
Heavy Color-Octet Particles at the LHC
Many new-physics models, especially those with a color-triplet top-quark
partner, contain a heavy color-octet state. The "naturalness" argument for a
light Higgs boson requires that the color-octet state be not much heavier than
a TeV, and thus it can be pair-produced with large cross sections at
high-energy hadron colliders. It may decay preferentially to a top quark plus a
top-partner, which subsequently decays to a top quark plus a color-singlet
state. This singlet can serve as a WIMP dark-matter candidate. Such decay
chains lead to a spectacular signal of four top quarks plus missing energy. We
pursue a general categorization of the color-octet states and their decay
products according to their spin and gauge quantum numbers. We review the
current bounds on the new states at the LHC and study the expected discovery
reach at the 8-TeV and 14-TeV runs. We also present the production rates at a
future 100-TeV hadron collider, where the cross sections will be many orders of
magnitude greater than at the 14-TeV LHC. Furthermore, we explore the extent to
which one can determine the color octet's mass, spin, and chiral couplings.
Finally, we propose a test to determine whether the fermionic color octet is a
Majorana particle.Comment: 20 pages, 9 figures; journal versio
Sigatoka-negra e ferrugem-asiática: duas doenças de grande impacto econômico.
Duas doenças têm merecido especial atenção do Ministério da Agricultura e Abastecimento (MAPA): A Sigatoka-negra da banana e a Ferrugem-asiática da soja, causadas, pelos respectivos fungos exóticos atuais, Mycosphaerella fijiensis M. Morelet (Paracercospora fijiensis (M. Morelet) Deighton) e Phakopsora pachyrhizi Sydow & P. Sydow. Estes foram, recentemente, introduzidos no País, sendo que, o primeiro tem distribuição restrita e o segundo se encontra amplamente disseminado no território brasileiro.bitstream/CENARGEN/27989/1/doc167.pd
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