12,303 research outputs found
Chronic lymphocytic leukaemia: Up-dated recommendations on diagnosis and treatment
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
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
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 . The continuum dressing with a
1064 nm laser, couples the same region of the continuum to the {4s }
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
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
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
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