252 research outputs found
Hypercyclic behaviour of operators in a hypercyclic C0-semigroup
AbstractLet {Tt}tâ©Ÿ0 be a hypercyclic strongly continuous semigroup of operators. Then each Tt (t>0) is hypercyclic as a single operator, and it shares the set of hypercyclic vectors with the semigroup. This answers in the affirmative a natural question concerning hypercyclic C0-semigroups. The analogous result for frequent hypercyclicity is also obtained
Pigmented purpuric dermatosis: a review of the literature
The pigmented purpuric dermatoses (PPDs) are a group of benign, chronic diseases. The variants described to date represent different clinical presentations of the same entity, all having similar histopathologic characteristics. We provide an overview of the most common PPDs and describe their clinical, dermatopathologic, and epiluminescence features. PPDs are both rare and benign, and this, together with an as yet poor understanding of the pathogenic mechanisms involved, means that no standardized treatments exist. We review the treatments described to date. However, because most of the descriptions are based on isolated cases or small series, there is insufficient evidence to support the use of any of these treatments as first-line therapy
Different coordination modes of an aryl-substituted hydrotris(pyrazolyl) borate ligand in rhodium and iridium complexes
Complexes TptolRh(C2H4)2 (1a) and TptolRh(CH2C(Me)C(Me)CH2) (1b) have been prepared by reaction of KTptol with the appropriate [RhCl(olefin)2]2 dimer (Tptol means hydrotris(3-p-tolylpyrazol-1-yl)borate). The two complexes show a dynamic behaviour that involves exchange between Îș2 and Îș3 coordination modes of the Tptol ligand. The iridium analogue, TptolIr(CH2C(Me)CHCH2) (2) has also been synthesized, and has been converted into the Ir(III) dinitrogen complex [(Îș4-N,N',N'',C-Tptol)Ir(Ph)(N2) (3) by irradiation with UV light under a dinitrogen atmosphere. Compound 3 constitutes a rare example of Ir(III)-N2 complex structurally characterized by X-ray crystallography. Its N2 ligand can be easily substituted by acetonitrile or ethylene upon heating and denticity changes in the Tptol ligand, from Îș4-N,N',N'',C (monometallated Tptol, from now on represented as TptolâČ) to Îș5-N,NâČ,Nâł,C,Câł (dimetallated Tp tol ligand, represented as Tptolâł) have been observed. When complex 3 is heated in the presence of acetylene, dimerization of the alkyne takes place to yield the enyne complex [(Îș5-N,NâČ,NâČâČ,C,CâČ-Tp tol)Ir(CH2CHCCH), 7̧ in which the unsaturated organic moiety is bonded to iridium through the carbon-carbon double bond.Ministerio de EducaciĂłn y Ciencia CTQ2007-62814Consolider-Ingenio 2010 CSD2007-00006Junta de AndalucĂa FQM-3151, FQM-672CONACYT 22934
Nonlinear resonance reflection from and transmission through a dense glassy system built up of oriented linear Frenkel chains: two-level models
A theoretical study of the resonance optical response of assemblies of
oriented short (as compared to an optical wavelength) linear Frenkel chains is
carried out using a two-level model. We show that both transmittivity and
reflectivity of the film may behave in a bistable fashion and analyze how the
effects found depend on the film thickness and on the inhomogeneous width of
the exciton optical transition.Comment: 26 pages, 9 figure
Chaotic asymptotic behaviour of the solutions of the Lighthill Whitham Richards equation
[EN] The phenomenon of chaos has been exhibited in mathematical nonlinear models that describe traffic flows, see, for instance (Li and Gao in Modern Phys Lett B 18(26-27):1395-1402, 2004; Li in Phys. D Nonlinear Phenom 207(1-2):41-51, 2005). At microscopic level, Devaney chaos and distributional chaos have been exhibited for some car-following models, such as the quick-thinking-driver model and the forward and backward control model (Barrachina et al. in 2015; Conejero et al. in Semigroup Forum, 2015). We present here the existence of chaos for the macroscopic model given by the Lighthill Whitham Richards equation.The authors are supported by MEC Project MTM2013-47093-P. The second and third authors are supported by GVA, Project PROMETEOII/2013/013Conejero, JA.; MartĂnez JimĂ©nez, F.; Peris Manguillot, A.; RĂłdenas EscribĂĄ, FDA. (2016). Chaotic asymptotic behaviour of the solutions of the Lighthill Whitham Richards equation. Nonlinear Dynamics. 84(1):127-133. https://doi.org/10.1007/s11071-015-2245-4S127133841Albanese, A.A., Barrachina, X., Mangino, E.M., Peris, A.: Distributional chaos for strongly continuous semigroups of operators. Commun. Pure Appl. Anal. 12(5), 2069â2082 (2013)Aroza, J., Peris, A.: Chaotic behaviour of birth-and-death models with proliferation. J. Differ. Equ. Appl. 18(4), 647â655 (2012)Banasiak, J., Lachowicz, M.: Chaos for a class of linear kinetic models. C. R. Acad. Sci. Paris SĂ©r. II 329, 439â444 (2001)Banasiak, J., Lachowicz, M.: Topological chaos for birth-and-death-type models with proliferation. Math. Models Methods Appl. Sci. 12(6), 755â775 (2002)Banasiak, J., MoszyĆski, M.: A generalization of DeschâSchappacherâWebb criteria for chaos. Discrete Contin. Dyn. Syst. 12(5), 959â972 (2005)Banasiak, J., MoszyĆski, M.: Dynamics of birth-and-death processes with proliferationâstability and chaos. Discrete Contin. Dyn. Syst. 29(1), 67â79 (2011)Barrachina, X., Conejero, J.A.: Devaney chaos and distributional chaos in the solution of certain partial differential equations. Abstr. Appl. Anal. Art. ID 457019, 11 (2012)Barrachina, X., Conejero, J.A., Murillo-Arcila, M., Seoane-SepĂșlveda, J.B.: Distributional chaos for the forward and backward control traffic model (2015, preprint)Bayart, F., Matheron, Ă.: Dynamics of Linear Operators, Cambridge Tracts in Mathematics, vol. 179. Cambridge University Press, Cambridge (2009)Bayart, F., Matheron, Ă.: Mixing operators and small subsets of the circle. J Reine Angew. Math. (2015, to appear)BermĂșdez, T., Bonilla, A., Conejero, J.A., Peris, A.: Hypercyclic, topologically mixing and chaotic semigroups on Banach spaces. Stud. Math. 170(1), 57â75 (2005)BermĂșdez, T., Bonilla, A., MartĂnez-GimĂ©nez, F., Peris, A.: Li-Yorke and distributionally chaotic operators. J. Math. Anal. Appl. 373(1), 83â93 (2011)Bernardes Jr, N.C., Bonilla, A., MĂŒller, V., Peris, A.: Distributional chaos for linear operators. J. Funct. Anal. 265(9), 2143â2163 (2013)Brackstone, M., McDonald, M.: Car-following: a historical review. Transp. Res. Part F Traffic Psychol. Behav. 2(4), 181â196 (1999)Conejero, J.A., Lizama, C., Rodenas, F.: Chaotic behaviour of the solutions of the MooreâGibsonâThompson equation. Appl. Math. Inf. Sci. 9(5), 1â6 (2015)Conejero, J.A., Mangino, E.M.: Hypercyclic semigroups generated by Ornstein-Uhlenbeck operators. Mediterr. J. Math. 7(1), 101â109 (2010)Conejero, J.A., MĂŒller, V., Peris, A.: Hypercyclic behaviour of operators in a hypercyclic C 0 -semigroup. J. Funct. Anal. 244, 342â348 (2007)Conejero, J.A., Murillo-Arcila, M., Seoane-SepĂșlveda, J.B.: Linear chaos for the quick-thinking-driver model. Semigroup Forum (2015). doi: 10.1007/s00233-015-9704-6Conejero, J.A., Peris, A., Trujillo, M.: Chaotic asymptotic behavior of the hyperbolic heat transfer equation solutions. Int. J. Bifur. Chaos Appl. Sci. Eng. 20(9), 2943â2947 (2010)Conejero, J.A., Rodenas, F., Trujillo, M.: Chaos for the hyperbolic bioheat equation. Discrete Contin. Dyn. Syst. 35(2), 653â668 (2015)Desch, W., Schappacher, W., Webb, G.F.: Hypercyclic and chaotic semigroups of linear operators. Ergod. Theory Dyn. Syst. 17(4), 793â819 (1997)Engel, K.-J., Nagel, R.: One-parameter semigroups for linear evolution equations, Graduate Texts in Mathematics, vol. 194. Springer, New York (2000). With contributions by S. Brendle, M. Campiti, T. Hahn, G. Metafune, G. Nickel, D. Pallara, C. Perazzoli, A. Rhandi, S. Romanelli and R. SchnaubeltGrosse-Erdmann, K.-G., Peris Manguillot, A.: Linear Chaos. Universitext. Springer, London (2011)Herzog, G.: On a universality of the heat equation. Math. Nachr. 188, 169â171 (1997)Li, K., Gao, Z.: Nonlinear dynamics analysis of traffic time series. Modern Phys. Lett. B 18(26â27), 1395â1402 (2004)Li, T.: Nonlinear dynamics of traffic jams. Phys. D Nonlinear Phenom. 207(1â2), 41â51 (2005)Lustri, C.: Continuum Modelling of Traffic Flow. Special Topic Report. Oxford University, Oxford (2010)Lighthill, M.J., Whitham, G.B.: On kinematic waves. II. A theory of traffic flow on long crowded roads. Proc. R. Soc. Lond. Ser. A. 229, 317â345 (1955)Maerivoet, S., De Moor, B.: Cellular automata models of road traffic. Phys. Rep. 419(1), 1â64 (2005)Mangino, E.M., Peris, A.: Frequently hypercyclic semigroups. Stud. Math. 202(3), 227â242 (2011)Murillo-Arcila, M., Peris, A.: Strong mixing measures for linear operators and frequent hypercyclicity. J. Math. Anal. Appl. 398, 462â465 (2013)Murillo-Arcila, M., Peris, A.: Strong mixing measures for C 0 -semigroups. Rev. R. Acad. Cienc. Exactas FĂs. Nat. Ser. A Math. RACSAM 109(1), 101â115 (2015)Pazy, A.: Semigroups of Linear Operators and Applications to Partial Differential Equations, Applied Mathematical Sciences, vol. 44. Springer, New York (1983)Protopopescu, V., Azmy, Y.Y.: Topological chaos for a class of linear models. Math. Models Methods Appl. Sci. 2(1), 79â90 (1992)Richards, P.I.: Shock waves on the highway. Oper. Res. 4, 42â51 (1956
A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator
Laser wakefield acceleration permits the generation of ultra-short,
high-brightness relativistic electron beams on a millimeter scale. While those
features are of interest for many applications, the source remains constraint
by the poor stability of the electron injection process. Here we present
results on injection and acceleration of electrons in pure nitrogen and argon.
We observe stable, continuous ionization-induced injection of electrons into
the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge
scales approximately linear with the laser energy and is limited by beam
loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per
shot, originating mostly from electrons of less than 10 MeV energy. The
relatively low energy, the high charge and its stability make this source
well-suited for applications such as non-destructive testing. Hence, we
demonstrate the production of energetic radiation via bremsstrahlung conversion
at 1 Hz repetition rate. In accordance with Geant4 Monte-Carlo simulations, we
measure a gamma-ray source size of less than 100 microns for a 0.5 mm tantalum
converter placed at 2 mm from the accelerator exit. Furthermore we present
radiographs of image quality indicators
Photonic Snake States in Two-Dimensional Frequency Combs
Taming the instabilities inherent to many nonlinear optical phenomena is of
paramount importance for modern photonics. In particular, the so-called snake
instability is universally known to severely distort localized wave stripes,
leading to the occurrence of transient, short-lived dynamical states that
eventually decay. The phenomenon is ubiquitous in nonlinear science, from river
meandering to superfluids, and to date it remains apparently uncontrollable.
However, here we show that optical snake instabilities can be harnessed by a
process that leads to the formation of stationary and robust two-dimensional
zigzag states. We find that such new type of nonlinear waves exists in the
hyperbolic regime of cylindrical micro-resonators and it naturally corresponds
to two-dimensional frequency combs featuring spectral heterogeneity and
intrinsic synchronization. We uncover the conditions of the existence of such
spatiotemporal photonic snakes and confirm their remarkable robustness against
perturbations. Our findings represent a new paradigm for frequency comb
generation, thus opening the door to a whole range of applications in
communications, metrology, and spectroscopy.Comment: 6 figures, 11 page
Chaotic differential operators
We give sufficient conditions for chaos of (differential) operators on Hilbert spaces of entire functions. To this aim we establish conditions on the coefficients of a polynomial P(z) such that P(B) is chaotic on the space lp, where B is the backward shift operator. © 2011 Springer-Verlag.This work was partially supported by the MEC and FEDER Projects MTM2007-64222, MTM2010-14909, and by GVA Project GV/2010/091, and by UPV Project PAID-06-09-2932. The authors would like to thank A. Peris for helpful comments and ideas that produced a great improvement of the paper's presentation. We also thank the referees for their helpful comments and for reporting to us a gap in Theorem 1.Conejero Casares, JA.; MartĂnez JimĂ©nez, F. (2011). Chaotic differential operators. Revista- Real Academia de Ciencias Exactas Fisicas Y Naturales Serie a Matematicas. 105(2):423-431. https://doi.org/10.1007/s13398-011-0026-6S4234311052Bayart, F., Matheron, Ă.: Dynamics of Linear Operators, Cambridge Tracts in Mathematics, vol. 179. Cambridge University Press, Cambridge (2009)BermĂșdez T., Miller V.G.: On operators T such that f(T) is hypercyclic. Integr. Equ. Oper. Theory 37(3), 332â340 (2000)Bonet J., MartĂnez-GimĂ©nez F., Peris A.: Linear chaos on FrĂ©chet spaces. Int. J. Bifur. Chaos Appl. Sci. Eng. 13(7), 1649â1655 (2003)Chan K.C., Shapiro J.H.: The cyclic behavior of translation operators on Hilbert spaces of entire functions. Indiana Univ. Math. J. 40(4), 1421â1449 (1991)Conejero J.A., MĂŒller V.: On the universality of multipliers on . J. Approx. Theory. 162(5), 1025â1032 (2010)deLaubenfels R., Emamirad H.: Chaos for functions of discrete and continuous weighted shift operators. Ergodic Theory Dyn. Syst. 21(5), 1411â1427 (2001)Devaney, R.L.: An introduction to chaotic dynamical systems, 2nd edn. In: Addison-Wesley Studies in Nonlinearity. Addison-Wesley Publishing Company Advanced Book Program, Redwood City (1989)Godefroy G., Shapiro J.H.: Operators with dense, invariant, cyclic vector manifolds. J. Funct. Anal. 98(2), 229â269 (1991)Grosse-Erdmann K.-G.: Hypercyclic and chaotic weighted shifts. Stud. Math. 139(1), 47â68 (2000)Grosse-Erdmann, K.-G., Peris, A.,: Linear chaos. Universitext, Springer, New York (to appear, 2011)Herzog G., Schmoeger C.: On operators T such that f(T) is hypercyclic. Stud. Math. 108(3), 209â216 (1994)Kahane, J.-P.: Some random series of functions, 2nd edn. In: Cambridge Studies in Advanced Mathematics, vol. 5. Cambridge University Press, Cambridge (1985)MartĂnez-GimĂ©nez F., Peris A.: Chaos for backward shift operators. Int. J. Bifur. Chaos Appl. Sci. Eng. 12(8), 1703â1715 (2002)MartĂnez-GimĂ©nez F.: Chaos for power series of backward shift operators. Proc. Am. Math. Soc. 135, 1741â1752 (2007)MĂŒller V.: On the Salas theorem and hypercyclicity of f(T). Integr. Equ. Oper. Theory 67(3), 439â448 (2010)Protopopescu V., Azmy Y.Y.: Topological chaos for a class of linear models. Math. Models Methods Appl. Sci. 2(1), 79â90 (1992)Rolewicz S.: On orbits of elements. Stud. Math. 32, 17â22 (1969)Salas H.N.: Hypercyclic weighted shifts. Trans. Am. Math. Soc. 347(3), 93â1004 (1995)Shapiro, J.H.: Simple connectivity and linear chaos. Rend. Circ. Mat. Palermo. (2) Suppl. 56, 27â48 (1998
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