Localized modes of binary mixtures of Bose-Einstein condensates in nonlinear optical lattices

The properties of the localized states of a two component Bose-Einstein condensate confined in a nonlinear periodic potential [nonlinear optical lattice] are investigated. We reveal the existence of new types of solitons and study their stability by means of analytical and numerical approaches. The symmetry properties of the localized states with respect to the NOL are also investigated. We show that nonlinear optical lattices allow the existence of bright soliton modes with equal symmetry in both components, bright localized modes of mixed symmetry type, as well as, dark-bright bound states and bright modes on periodic backgrounds. In spite of the quasi 1D nature of the problem, the fundamental symmetric localized modes undergo a delocalizing transition when the strength of the nonlinear optical lattice is varied. This transition is associated with the existence of an unstable solution, which exhibits a shrinking (decaying) behavior for slightly overcritical (undercritical) variations in the number of atoms.Comment: 13 pages, 14 figure

Quantum-tunneling dynamics of a spin-polarized Fermi gas in a double-well potential

We study the exact dynamics of a one-dimensional spin-polarized gas of fermions in a double-well potential at zero and finite temperature. Despite the system is made of non-interacting fermions, its dynamics can be quite complex, showing strongly aperiodic spatio-temporal patterns during the tunneling. The extension of these results to the case of mixtures of spin-polarized fermions in interaction with self-trapped Bose-Einstein condensates (BECs) at zero temperature is considered as well. In this case we show that the fermionic dynamics remains qualitatively similar to the one observed in absence of BEC but with the Rabi frequencies of fermionic excited states explicitly depending on the number of bosons and on the boson-fermion interaction strength. From this, the possibility to control quantum fermionic dynamics by means of Feshbach resonances is suggested.Comment: Accepted for publication in Phys. Rev.

Soliton ratchets induced by ac forces with harmonic mixing

The ratchet dynamics of a kink (topological soliton) of a dissipative sine-Gordon equation in the presence of ac forces with harmonic mixing (at least bi-harmonic) of zero mean is studied. The dependence of the kink mean velocity on system parameters is investigated numerically and the results are compared with a perturbation analysis based on a point particle representation of the soliton. We find that first order perturbative calculations lead to incomplete descriptions, due to the important role played by the soliton-phonon interaction in establishing the phenomenon. The role played by the temporal symmetry of the system in establishing soliton ratchets is also emphasized. In particular, we show the existence of an asymmetric internal mode on the kink profile which couples to the kink translational mode through the damping in the system. Effective soliton transport is achieved when the internal mode and the external force get phase locked. We find that for kinks driven by bi-harmonic drivers consisting of the superposition of a fundamental driver with its first odd harmonic, the transport arises only due to this {\it internal mode} mechanism, while for bi-harmonic drivers with even harmonic superposition, also a point-particle contribution to the drift velocity is present. The phenomenon is robust enough to survive the presence of thermal noise in the system and can lead to several interesting physical applications.Comment: 9 pages, 13 figure

Matter-wave 2D solitons in crossed linear and nonlinear optical lattices

It is demonstrated the existence of multidimensional matter-wave solitons in a crossed optical lattice (OL) with linear OL in the $x-$direction and nonlinear OL (NOL) in the $y-$direction, where the NOL can be generated by a periodic spatial modulation of the scattering length using an optically induced Feshbach resonance. In particular, we show that such crossed linear and nonlinear OL allows to stabilize two-dimensional (2D) solitons against decay or collapse for both attractive and repulsive interactions. The solutions for the soliton stability are investigated analytically, by using a multi-Gaussian variational approach (VA), with the Vakhitov-Kolokolov (VK) necessary criterion for stability; and numerically, by using the relaxation method and direct numerical time integrations of the Gross-Pitaevskii equation (GPE). Very good agreement of the results corresponding to both treatments is observed.Comment: 8 pages (two-column format), with 16 eps-files of 4 figure

Compactons in Nonlinear Schr\"odinger Lattices with Strong Nonlinearity Management

The existence of compactons in the discrete nonlinear Schr\"odinger equation in the presence of fast periodic time modulations of the nonlinearity is demonstrated. In the averaged DNLS equation the resulting effective inter-well tunneling depends on modulation parameters {\it and} on the field amplitude. This introduces nonlinear dispersion in the system and can lead to a prototypical realization of single- or multi-site stable discrete compactons in nonlinear optical waveguide and BEC arrays. These structures can dynamically arise out of Gaussian or compactly supported initial data.Comment: 4 pages, 4 figure

Review about comorbidities of behavioural disorders in children and adolescents: The focus on attention-deficit/hyperactivity disorder

Disruptive behavior disorders (DBD) present high comorbidity rate mainly for opposite-defiant disorders that are frequent among children, adolescents and adults affected by with attention deficit and hyperactivity disorder (ADHD), probably as result of common temperamental risk factors such as attention, distraction, impulsivity. ADHD tend to manifest in about 50% of individuals diagnosed as disruptive behavioral disorders

Behavioural disorders in children and adolescents: A conceptual review about the therapeutic alliance with family and school

Aim: In disruptive behavioral disorders, given the wide range of symptomatic manifestations and the complexity of the sociofamiliar contexts in which they develop, it is now proven that more visible and more stable results can be achieved over time through multimodal and multidimensional interventions. These are accomplished through the integration of psychotherapeutic interventions for the child and parents, counseling interventions for all the various practitioners who come into contact with the child in school, sports, and social settings, through the possibility of organizing multiple settings in patient can be followed by several health professionals such as child and adolescent neuropsychiatrist, neuropsychomotricist, occupation therapist, psychologist

Adiabatic Compression of Soliton Matter Waves

The evolution of atomic solitary waves in Bose-Einstein condensate (BEC) under adiabatic changes of the atomic scattering length is investigated. The variations of amplitude, width, and velocity of soliton are found for both spatial and time adiabatic variations. The possibility to use these variations to compress solitons up to very high local matter densities is shown both in absence and in presence of a parabolic confining potential.Comment: to appear in J.Phys.

Forensic considerations on violent parasomnias during lifespan

Nocturnal parasomnias are a group of sleep complex manifestation that don't alter the sleep macrostructure, but when persistent during adulthood may be assume violent aspects with relevant forensic implications about the guiltiness

The behavioral parenting interventions (BPT) for support and mandatory integrative therapy for children and adolescents affected by disruptive behavioural disorders: A brief review

The behavioral parenting interventions (BPT), commonly abbreviated as parent training, is a program conducted by an expert with the specific purpose of improving or modifying parental practices in order to promote the child's well-being, increasing parenting skills in the daily management of the child, problem solving and reducing the level of parenting and family stress. BPT presents many positive effects on children or adolescents affected by neurodevelopmental disorder such as ADHD, autism and cognitive dysfunction but BPT appears to improve also other proximal outcomes such as parenting competence and parenting stress