We present a dynamical model that successfully explains the observed time evolution of the magnetization in diluted magnetic semiconductor quantum wells after weak laser excitation. Based on the ...pseudo-fermion formalism and a second-order many-particle expansion of the exact p-d exchange interaction, our approach goes beyond the usual mean-field approximation. It includes both the sub-picosecond demagnetization dynamics and the slower relaxation processes that restore the initial ferromagnetic order in a nanosecond timescale. In agreement with experimental results, our numerical simulations show that, depending on the value of the initial lattice temperature, a subsequent enhancement of the total magnetization may be observed within the timescale of a few hundred picoseconds.
We present a dynamical model that reproduces the observed time evolution of the magnetization in diluted magnetic semiconductor films after weak laser excitation. Based on a many-particle expansion ...of the exact p–d exchange interaction, our approach goes beyond the usual mean-field approximation. Numerical results demonstrate that the hole spin relaxation plays a crucial role for explaining the ultrafast demagnetization processes observed experimentally. The influence of the laser power on the magnetization dynamics is also investigated.
The need for a collaborative approach to complex inherited diseases collectively referred to as laminopathies, encouraged Italian researchers, geneticists, physicians and patients to join in the ...Italian Network for Laminopathies, in 2009. Here, we highlight the advantages and added value of such a multidisciplinary effort to understand pathogenesis, clinical aspects and try to find a cure for Emery-Dreifuss muscular dystrophy, Mandibuloacral dysplasia, Hutchinson-Gilford Progeria and forms of lamin-linked cardiomyopathy, neuropathy and lipodystrophy.
Patients with muscle pathology are a challenge for anaesthesiologists because of possible life-threatening general anaesthesia complications. A review of the current medical literature on the issue ...clearly indicates that increasing awareness by anaesthesiologists in recent years has led to a reduction in the occurrence of adverse events in patients with diagnostically well-defined muscle disease. On the other hand, the current emerging aspect is that the great majority of complications concern subjects with clinically non-overt (silent to mildly symptomatic) and thus undiagnosed myopathy. With a view to improving prevention of possible critical anaesthesia complications in such patients, we present a "Safe Anaesthesia Table", listing both the anaesthetic drugs to be avoided and those considered harmless for myopathic patients, irrespective of age and type of pathology. In addition, a brief outline about the clinical aspects suggestive of a possible muscle pathology is also provided. Using "safe drugs" during routine surgical procedures in subjects with suspected undiagnosed myopathy will enable the anaesthesiologist to avoid delaying surgery, while protecting them from anaesthesia complications. By following this approach the presumed myopathy can be properly investigated after surgery.
Ultrafast magnetization dynamics in diluted magnetic semiconductors is investigated using a model based on the pseudofermion formalism and a third-order many-particle expansion of the exact pd ...exchange interaction. Dynamical RKKY-like interactions and double-exchange mechanism based on the Kondo interaction emerge naturally from our approach. Our analysis reveals that the many-particle expansion is not generally well defined and an infrared Kondo-like divergence can occur. In particular, the bare polarization propagator fails to converge in the presence of a highly confined hole gas and an enhancement of the ion-hole spin correlation is found for low-dimensional systems. Finally, numerical simulations have been performed on GaMnAs and show that dynamical many-particle correlations play a significant role in the time evolution of the total magnetization.
We develop a numerical model that reproduces the thermal equilibrium and the spin transfer mechanisms in magnetic nanomaterials. We analyze the coherent two-particle spin exchange interaction and the ...electron-electron collisions. Our study is based on a quantum atomistic approach and the particle dynamics is performed by using a Monte Carlo technique. The coherent quantum evolution of the atoms is interrupted by instantaneous collisions with itinerant electrons. The collision processes are associated to the quantum collapse of the local atomic wave function. We show that particle-particle interactions beyond the molecular field approximation can be included in this framework. Our model is able to reproduce the thermal equilibrium and strongly out-of-equilibrium phenomena such as the ultrafast dynamics of the magnetization in nanomatrials.
With the ever increasing amount of traffic, scalability is probably the most important factor that differentiates several existing approaches to traffic classification. This paper focuses on ...payload-based classification and compares the results obtained through a "lightweight" traffic classification approach with the ones obtained with a "completely stateful" approach, demonstrating that the first approach, albeit less precise, is still appropriate for a large class of applications.
A quantum model based on a Euler-Lagrange variational approach is proposed. In analogy with the classical transport, our approach maintain the description of the particle motion in terms of ...trajectories in a configuration space. Our method is designed to describe correction to the motion of nearly localized particles due to quantum phenomena. We focus on the simulation of the motion of light nuclei in ab initio calculations. Similarly to the Gaussian beam method, our approach is based on a ansatz for the particle wave function. We discuss the completeness of our ansatz and the connection of our results with the Bohm trajectories approach.
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