Is CIMT a rehabilitative practice for everyone? Predictive factors and feasibility.

BACKGROUND: Constraint Induced Movement Therapy (CIMT) in hemiplegic patient is an efficacious method for upper limb rehabilitation. AIM: To verify the applicability of CIMT in post stroke inpatients and to verify the predictive value of some clinical and functional independent variables on the outcomes, in order to identify a population of subjects to which this technique can be more effective. DESIGN: Non-controlled clinical study. SETTING: Seven Italian, non-experimental, Rehabilitation Departments. MATERIALS AND METHODS: All post-stroke inpatients (subacute and chronic), consecutively admitted in 7 Rehabilitation Departments, were screened according to our inclusion criteria. The eligible population was assessed according to selected clinical and functional variables at the baseline, and it was evaluated with Wolf Motor Function Test (WMFT-FAS and WMFT-PTT) and Motor Activity Log (MAL-AOU and MAL-QOM), before treatment (T0), after treatment (T1) and at a 3-month follow up (T2). Patients underwent 2 weeks of CIMT from T0. RESULTS: Of the 600 inpatients screened, 44 were admitted in the CIMT protocol and were evaluated at T0 and T1; just 24 completed the assessment at T2. At the end of treatment NIHSS and Motricity Index (MI) were predictive factors of MAL scores, while Geriatric Depression Scale (GDS), Modified Barthel Inedx (MBI) and MI were predictive factors of WMFT scores. At the follow up NIHSS and GDS remained predictive factors of MAL scores, and MBI was predictive of WMFT FAS score. CONCLUSION: CIMT efficacy did not result to be related to patient's age, mild cognitive deficit, time since stroke. Depression and pinch ability are the main predictors of motor recovery. Despite the demonstrated efficacy, CIMT feasibility still needs to be demonstrated, considering the low percentage (6.5%) of eligibility among all stroke inpatients. CLINICAL REHABILITATION IMPACT: CIMT requires high costs and resources; therefore it is valuable to know the predictive factors which help select the eligible patients. It is then useful to recognize the risk factors of developing Learned Non Use after stroke.

Stability of quantum motion in regular systems: a uniform semiclassical approach.

We study the stability of quantum motion of classically regular systems in the presence of small perturbations. On the basis of a uniform semiclassical theory we derive the fidelity decay which displays a quite complex behavior, from Gaussian to power law decay t(-alpha), with 1

Uniform semiclassical approach to fidelity decay in the deep Lyapunov regime.

We use the uniform semiclassical approximation in order to derive the fidelity decay in the regime of large perturbations. Numerical computations are presented which agree with our theoretical predictions. Moreover, our theory allows us to explain previous findings, such as the deviation from the Lyapunov decay rate in cases where the classical finite-time instability is nonuniform in phase space.

Stability of quantum motion: beyond Fermi-golden-rule and Lyapunov decay.

We study, analytically and numerically, the stability of quantum motion for a classically chaotic system. We show the existence of different regimes of fidelity decay. In particular, when the underlying classical dynamics is weakly chaotic, deviations from Fermi-golden-rule and Lyapounov regimes are observed and discussed.

Quantum phase transition in the Frenkel-Kontorova chain: from pinned instanton glass to sliding phonon gas.

We study analytically and numerically the one-dimensional quantum Frenkel-Kontorova chain in the regime where the classical model is located in the pinned phase characterized by the gaped phonon excitations and devil's staircase. By extensive quantum Monte Carlo simulations, we show that for the effective Planck constant Planck smaller than the critical value Planck(c) the quantum chain is in the pinned instanton glass phase. In this phase, the elementary excitations have two branches: phonons, separated from zero energy by a finite gap, and instantons that have an exponentially small excitation energy. At Planck = Planck(c) the quantum phase transition takes place and for Planck > Planck(c) the pinned instanton glass is transformed into the sliding phonon gas with gapless phonon excitations. This transition is accompanied by the divergence of the spatial correlation length and appearance of sliding modes at Planck > Planck(c).

Fractal spin glass properties of low energy configurations in the Frenkel-Kontorova chain.

We study, numerically and analytically, the classical one-dimensional Frenkel-Kontorova chain in the regime of pinned phase characterized by phonon gap. Our results show the existence of exponentially many static equilibrium configurations that are exponentially close to the energy of the ground state. The energies of these configurations form a fractal quasidegenerate band structure that is described on the basis of elementary excitations. Contrary to the ground state, the configurations inside these bands are disordered.

Semiquantal approach to finite systems of interacting particles.

A novel approach is suggested for the statistical description of quantum systems of interacting particles. We show that the occupation numbers for single-particle states can be represented as a convolution of a classical analog of the eigenstate, with the quantum occupation number for noninteracting particles. The latter takes into account the wave function symmetry and depends on the unperturbed energy spectrum only. As a result, the distribution of occupation numbers n(s) can be found even for a large number of interacting particles. Using the model of interacting spins, we demonstrate that this approach gives a correct description of n(s) even in deep quantum regions with few single-particle orbitals.

Controlling the energy flow in nonlinear lattices: a model for a thermal rectifier.

We address the problem of heat conduction in 1D nonlinear chains; we show that, acting on the parameter which controls the strength of the on-site potential inside a segment of the chain, we induce a transition from conducting to insulating behavior in the whole system. Quite remarkably, the same transition can be observed by increasing the temperatures of the thermal baths at both ends of the chain by the same amount. The control of heat conduction by nonlinearity opens the possibility to propose new devices such as a thermal rectifier.

Efficient quantum computing of complex dynamics.

We propose a quantum algorithm which uses the number of qubits in an optimal way and efficiently simulates a physical model with rich and complex dynamics described by the quantum sawtooth map. The numerical study of the effect of static imperfections in the quantum computer hardware shows that the main elements of the phase space structures are accurately reproduced up to a time scale which is polynomial in the number of qubits. The errors generated by these imperfections are more significant than the errors of random noise in gate operations.

Quantum fractal fluctuations.

We numerically analyze quantum survival probability fluctuations in an open, classically chaotic system. In a quasiclassical regime and in the presence of classical mixed phase space, such fluctuations are believed to exhibit a fractal pattern, on the grounds of semiclassical arguments. In contrast, we work in a classical regime of complete chaoticity and in a deep quantum regime of strong localization. We provide evidence that fluctuations are still fractal, due to the slow, purely quantum algebraic decay in time produced by dynamical localization. Such findings considerably enlarge the scope of the existing theory.

Regular and anomalous quantum diffusion in the Fibonacci kicked rotator.

We study the dynamics of a quantum rotator, impulsively kicked according to the almost-periodic Fibonacci sequence. A special numerical technique allows us to carry on this investigation for as many as 10(12) kicks. It is shown that above a critical kick strength, the excitation of the system is well described by regular diffusion, while below this border it becomes anomalous and subdiffusive. A law for the dependence of the exponent of anomalous subdiffusion on the kick strength is established numerically. The analogy between these results and quantum diffusion in models of quasicrystals and in the kicked Harper system is discussed.

Synthesis and LC characterization of clenbuterol molecularly imprinted polymers.

Highly selective non-covalent clenbuterol (CL) imprinted polymers were prepared using methacrylic acid as monomer and ethylene glycol dimethacrylate as cross-linking agent. HPLC experiments with columns packed with this material showed that CL are selectively recognised with respect to all other adrenergic substances studied using a phosphate buffer/acetonitrile eluent. The separation was strongly dependent on pH and the organic/aqueous phase ratio. An important contribution to the recognition mechanism from hydrophobic interactions was found at higher water content. These results demonstrate that a novel family of absorbents with high selectivity for CL was obtained which can be exploited in solid phase extractions or as recognition elements for selective sensors.

Triangle map: A model of quantum chaos

We study an area preserving parabolic map which emerges from the Poincare map of a billiard particle inside an elongated triangle. We provide numerical evidence that the motion is ergodic and mixing. Moreover, when considered on the cylinder, the motion appears to follow a Gaussian diffusive process.

Quantum resonances of the kicked rotor and the SU(q) group

The quantum kicked rotor map is embedded into a continuous unitary transformation generated by a time-independent quasi Hamiltonian. In some vicinity of a quantum resonance of order q, we relate the problem to the regular motion along a circle in a (q(2)-1) component inhomogeneous "magnetic" field of a quantum particle with q intrinsic degrees of freedom described by the SU(q) group. This motion is in parallel with the classical phase oscillations near a nonlinear resonance.

Quantum resonances and regularity islands in quantum maps

We study analytically as well as numerically the dynamics of a quantum map near a quantum resonance of an order q. The map is embedded into a continuous unitary transformation generated by a time-independent quasi-Hamiltonian. Such a Hamiltonian generates at the very point of the resonance a local gauge transformation described by the unitary unimodular group SU(q). The resonant energy growth is attributed to the zero Liouville eigenmodes of the generator in the adjoint representation of the group while the nonzero modes yield saturating with time contribution. In a vicinity of a given resonance, the quasi-Hamiltonian is then found in the form of power expansion with respect to the detuning from the resonance. The problem is related in this way to the motion along a circle in a (q2 - 1)-component inhomogeneous "magnetic" field of a quantum particle with q intrinsic degrees of freedom described by the SU(q) group. This motion is in parallel with the classical phase oscillations near a nonlinear resonance. The most important role is played by the resonances with the orders much smaller than the typical localization length q << l. Such resonances master for exponentially long though finite times the motion in some domains around them. Explicit analytical solution is possible for a few lowest and strongest resonances.

Fractal survival probability fluctuations

We study fluctuations of survival probability in an open quantum system classically described by a map with a mixed phase space. Our results provide the first numerical support to theoretical predictions that such fluctuations have a fractal structure, quantitatively related to the algebraic decay of the classical survival probability.

Quantum Poincare recurrences for a hydrogen atom in a microwave field

We study the time dependence of the ionization probability of Rydberg atoms driven by a microwave field, both in classical and in quantum mechanics. The quantum survival probability follows the classical one up to the Heisenberg time and then decays algebraically as P(t) approximately 1/t. This decay law derives from the exponentially long times required to escape from some region of the phase space, due to tunneling and localization effects. We also provide parameter values which should allow one to observe such decay in laboratory experiments.