Assuntos
Ataxia/tratamento farmacológico , Isquemia Encefálica/complicações , Extratos Vegetais/uso terapêutico , Doenças Vestibulares/tratamento farmacológico , Adulto , Idoso , Ataxia/etiologia , Quimioterapia Combinada , Feminino , Ginkgo biloba , Humanos , Masculino , Pessoa de Meia-Idade , Síndrome , Doenças Vestibulares/etiologiaRESUMO
The study was conducted in 3 Russian centers (Moscow, St. Petersburg and Nizhniy Novgorod). The total sample included 110 patients whose mental state met the definition of <
Assuntos
Doença de Alzheimer/prevenção & controle , Aminoácidos/administração & dosagem , Transtornos Cognitivos/tratamento farmacológico , Fármacos Neuroprotetores/administração & dosagem , Alcaloides de Vinca/administração & dosagem , Administração Oral , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/complicações , Doença de Alzheimer/fisiopatologia , Cognição/efeitos dos fármacos , Transtornos Cognitivos/complicações , Transtornos Cognitivos/fisiopatologia , Relação Dose-Resposta a Droga , Feminino , Seguimentos , Humanos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Síndrome , Fatores de Tempo , Resultado do TratamentoRESUMO
We study solitons and vortices described by the (2+1)-dimensional fourth-order generalized nonlinear Schrödinger equation with cubic-quintic nonlinearity. Necessary conditions for the existence of such structures are investigated analytically using conservation laws and asymptotic behavior of localized solutions. We derive the generalized virial relation, which describes the combined influence of linear and nonlinear effects on the evolution of the wave packet envelope. By means of refined variational analysis, we predict the main features of steady soliton solutions, which have been shown to be in good agreement with our numerical results. Soliton and vortex stability is investigated by linear analysis and direct numerical simulations. We show that stable bright solitons exist in nonlinear Kerr media both in anomalous and normal dispersive regimes, even if only the fourth-order dispersive effect is taken into account. Vortices occur robust with respect to symmetry-breaking azimuthal instability only in the presence of additional defocusing quintic nonlinearity in the strongly nonlinear regime. We apply our results to the theoretical explanation of whistler self-induced waveguide propagation in plasmas, and discuss possible applications to light beam propagation in cubic-quintic optical materials and to solitons in two-dimensional molecular systems.