11,328 research outputs found

    Chronic lymphocytic leukaemia: Up-dated recommendations on diagnosis and treatment

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    Diagnosis and treatment of chronic lymphatic leukaemia (CLL) are currently undergoing great change. New knowledge of prognosis factors and the numerous new therapeutic procedures now available, such as purine analogues, high-dose treatment and monoclonal antibodies are making major contributions to this progress. As a consequence, the options for treatment of CLL are considerably more diverse now than a few years ago, and now include procedures that take into account age and risk. At the same time, it should be emphasized that many important questions regarding the treatment of CLL remain unresolved. It is anticipated that these questions will be answered over the coming few years by including patients in multicentre studies like those being carried out by the German CLL study group

    Coherent population transfer beyond the adiabatic limit: generalized matched pulses and higher-order trapping states

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    We show that the physical mechanism of population transfer in a 3-level system with a closed loop of coherent couplings (loop-STIRAP) is not equivalent to an adiabatic rotation of the dark-state of the Hamiltonian but coresponds to a rotation of a higher-order trapping state in a generalized adiabatic basis. The concept of generalized adiabatic basis sets is used as a constructive tool to design pulse sequences for stimulated Raman adiabatic passage (STIRAP) which give maximum population transfer also under conditions when the usual condition of adiabaticty is only poorly fulfilled. Under certain conditions for the pulses (generalized matched pulses) there exists a higher-order trapping state, which is an exact constant of motion and analytic solutions for the atomic dynamics can be derived.Comment: 15 pages, 9 figure

    Photoionization Suppression by Continuum Coherence: Experiment and Theory

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    We present experimental and theoretical results of a detailed study of laser-induced continuum structures (LICS) in the photoionization continuum of helium out of the metastable state 2s 1S0^1S_0. The continuum dressing with a 1064 nm laser, couples the same region of the continuum to the {4s 1S0^1S_0} state. The experimental data, presented for a range of intensities, show pronounced ionization suppression (by as much as 70% with respect to the far-from-resonance value) as well as enhancement, in a Beutler-Fano resonance profile. This ionization suppression is a clear indication of population trapping mediated by coupling to a contiuum. We present experimental results demonstrating the effect of pulse delay upon the LICS, and for the behavior of LICS for both weak and strong probe pulses. Simulations based upon numerical solution of the Schr\"{o}dinger equation model the experimental results. The atomic parameters (Rabi frequencies and Stark shifts) are calculated using a simple model-potential method for the computation of the needed wavefunctions. The simulations of the LICS profiles are in excellent agreement with experiment. We also present an analytic formulation of pulsed LICS. We show that in the case of a probe pulse shorter than the dressing one the LICS profile is the convolution of the power spectra of the probe pulse with the usual Fano profile of stationary LICS. We discuss some consequences of deviation from steady-state theory.Comment: 29 pages, 17 figures, accepted to PR

    Non-destructive testing of carbon reinforced plastics by means of phase retrieval

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    In this work, the SLM-based phase retrieval system will be used to inspect carbon reinforced plastics samples (CFRP) under applying a thermal load. For this purpose, the system is used to capture a sequence of 8 spatially separated recording planes, where the distance between subsequent planes equals 2 mm. For detecting the hidden failures two sets of intensity observations are recorded. The first set for the initial state and the second set is captured after applying the load. To recover the phase information associated with the two states, the captured intensities have been subjected to an iterative algorithm based on the method of generalized projection.Comment: Conf. Speckle 201

    Measuring a coherent superposition

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    We propose a simple method for measuring the populations and the relative phase in a coherent superposition of two atomic states. The method is based on coupling the two states to a third common (excited) state by means of two laser pulses, and measuring the total fluorescence from the third state for several choices of the excitation pulses.Comment: 7 pages, 1 figure, twocolumn REVTe