112 research outputs found

    Policy and model analysis : the case of soviet immigrant teacher re-training in Israel

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    This paper presents an evaluation study of the re-training programme for immigrant science teachers from former USSR (FSU) that took place in Israeli universities and teacher-training colleges for the first time during 1990-1991 following the mass immigration from FSU. The main criterion for this evaluation was the degree to which the re-training programmes catered to professional, social and cultural inherent affecting factors and met the aims of the re-training policy. On the basis of this study, a list of policy recommendations is offered. The re-training considerations and the models identified in this study might be applied in countries where major social changes, such as immigration or recession, occur.peer-reviewe

    The gap between intention and attainment in policy implementation : a syndrome revisited : the case of the reform in technological studies in Israel

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    This study analyses the syndrome inherent in the gap between policy setting and policy implementation, as exemplified by the case of the reform in the high-school system initiated by the Israeli Ministry of Education's Technological Division. The reform policy in the Technological trend prompted by the great advances in this field in recent years is explored, and the degree of its expected versus de facto implementation is analysed. The measurement tool for degree of implementation is the comparative requirements of the final matriculation exams before and after the beginning of the reform. The analysis focuses on the electronics and electricity trends. It challenges the validity of the proposed reform implementation and disputes the· validity of the matriculation exams as a tool meant to assess reform implementation. The gap between the initial intention of the policy makers and actual policy implementation will be analysed and discussed.peer-reviewe

    Infrared Laser Driven Double Proton Transfer. An Optimal Control Theory Study

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    Laser control of ultrafast double proton transfer is investigated for a two-dimensional model system describing stepwise and concerted transfer pathways. The pulse design has been done by employing optimal control theory in combination with the multiconfiguration time-dependent Hartree wave packet propagation. The obtained laser fields correspond to multiple pump-dump pulse sequences. Special emphasis is paid to the relative importance of stepwise and concerted transfer pathways for the driven wave packet and its dependence on the parameters of the model Hamiltonian as well as on the propagation time. While stepwise transfer is dominating in all cases considered, for high barrier systems concerted transfer proceeding via tunneling can make a contribution.Comment: 9 figure

    Electronic Coherence Dephasing in Excitonic Molecular Complexes: Role of Markov and Secular Approximations

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    We compare four different types of equations of motion for reduced density matrix of a system of molecular excitons interacting with thermodynamic bath. All four equations are of second order in the linear system-bath interaction Hamiltonian, with different approximations applied in their derivation. In particular we compare time-nonlocal equations obtained from so-called Nakajima-Zwanzig identity and the time-local equations resulting from the partial ordering prescription of the cummulant expansion. In each of these equations we alternatively apply secular approximation to decouple population and coherence dynamics from each other. We focus on the dynamics of intraband electronic coherences of the excitonic system which can be traced by coherent two-dimensional spectroscopy. We discuss the applicability of the four relaxation theories to simulations of population and coherence dynamics, and identify features of the two-dimensional coherent spectrum that allow us to distinguish time-nonlocal effects.Comment: 14 pages, 8 figure

    Quantum Two-State Dynamics Driven by Stationary Non-Markovian Discrete Noise: Exact Results

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    We consider the problem of stochastic averaging of a quantum two-state dynamics driven by non-Markovian, discrete noises of the continuous time random walk type (multistate renewal processes). The emphasis is put on the proper averaging over the stationary noise realizations corresponding, e.g., to a stationary environment. A two state non-Markovian process with an arbitrary non-exponential distribution of residence times (RTDs) in its states with a finite mean residence time provides a paradigm. For the case of a two-state quantum relaxation caused by such a classical stochastic field we obtain the explicit exact, analytical expression for the averaged Laplace-transformed relaxation dynamics. In the limit of Markovian noise (implying an exponential RTD), all previously known results are recovered. We exemplify new more general results for the case of non-Markovian noise with a biexponential RTD. The averaged, real-time relaxation dynamics is obtained in this case by numerically exact solving of a resulting algebraic polynomial problem. Moreover, the case of manifest non-Markovian noise with an infinite range of temporal autocorrelation (which in principle is not accessible to any kind of perturbative treatment) is studied, both analytically (asymptotic long-time dynamics) and numerically (by a precise numerical inversion of the Laplace-transformed averaged quantum relaxation).Comment: Chemical Physics, in pres

    Quantum dynamics in strong fluctuating fields

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    A large number of multifaceted quantum transport processes in molecular systems and physical nanosystems can be treated in terms of quantum relaxation processes which couple to one or several fluctuating environments. A thermal equilibrium environment can conveniently be modelled by a thermal bath of harmonic oscillators. An archetype situation provides a two-state dissipative quantum dynamics, commonly known under the label of a spin-boson dynamics. An interesting and nontrivial physical situation emerges, however, when the quantum dynamics evolves far away from thermal equilibrium. This occurs, for example, when a charge transferring medium possesses nonequilibrium degrees of freedom, or when a strong time-dependent control field is applied externally. Accordingly, certain parameters of underlying quantum subsystem acquire stochastic character. Herein, we review the general theoretical framework which is based on the method of projector operators, yielding the quantum master equations for systems that are exposed to strong external fields. This allows one to investigate on a common basis the influence of nonequilibrium fluctuations and periodic electrical fields on quantum transport processes. Most importantly, such strong fluctuating fields induce a whole variety of nonlinear and nonequilibrium phenomena. A characteristic feature of such dynamics is the absence of thermal (quantum) detailed balance.Comment: review article, Advances in Physics (2005), in pres

    Re-visiting Meltsner: Policy Advice Systems and the Multi-Dimensional Nature of Professional Policy Analysis

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    10.2139/ssrn.15462511-2
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