17,040 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

    The Superconducting Proximity Effect as a Tool to Investigate Metal Films and Interfaces

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    052The superconducting proximity effect is measured in sandwiches of thin Pb films and the alkali metals Cs, Rb, K and Na. The TcT_{c}-dependence provides information about the interface barriers between Pb and the alkalis. Such a barrier is particularly large in Pb/Cs sandwiches. It is not due to impurities or oxydation. In the presence of a sufficiently strong barrier a special form of the Cooper limit can be applied to calculate the transition temperature of the sandwich

    Black hole singularities: a new critical phenomenon

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    The singularitiy inside a spherical charged black hole, coupled to a spherical, massless scalar field is studied numerically. The profile of the characteristic scalar field was taken to be a power of advanced time with an exponent α>0\alpha>0. A critical exponent αcrit\alpha_{\rm crit} exists. For exponents below the critical one (α<αcrit\alpha<\alpha_{\rm crit}) the singularity is a union of spacelike and null sectors, as is also the case for data with compact support. For exponents greater than the critical one (α>αcrit\alpha>\alpha_{\rm crit}) an all-encompassing, spacelike singularity evolves, which completely blocks the ``tunnel'' inside the black hole, preventing the use of the black hole as a portal for hyperspace travel.Comment: 4 pages, 5 eps figures; An Erratum is added. The main conclusions of the original Letter are unchange

    Longitudinal Atomic Beam Spin Echo Experiments: A possible way to study Parity Violation in Hydrogen

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    We discuss the propagation of hydrogen atoms in static electric and magnetic fields in a longitudinal atomic beam spin echo (lABSE) apparatus. Depending on the choice of the external fields the atoms may acquire both dynamical and geometrical quantum mechanical phases. As an example of the former, we show first in-beam spin rotation measurements on atomic hydrogen, which are in excellent agreement with theory. Additional calculations of the behaviour of the metastable 2S states of hydrogen reveal that the geometrical phases may exhibit the signature of parity-(P-)violation. This invites for possible future lABSE experiments, focusing on P-violating geometrical phases in the lightest of all atoms.Comment: 6 pages, 4 figure

    TinkerCell: Modular CAD Tool for Synthetic Biology

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    Synthetic biology brings together concepts and techniques from engineering and biology. In this field, computer-aided design (CAD) is necessary in order to bridge the gap between computational modeling and biological data. An application named TinkerCell has been created in order to serve as a CAD tool for synthetic biology. TinkerCell is a visual modeling tool that supports a hierarchy of biological parts. Each part in this hierarchy consists of a set of attributes that define the part, such as sequence or rate constants. Models that are constructed using these parts can be analyzed using various C and Python programs that are hosted by TinkerCell via an extensive C and Python API. TinkerCell supports the notion of a module, which are networks with interfaces. Such modules can be connected to each other, forming larger modular networks. Because TinkerCell associates parameters and equations in a model with their respective part, parts can be loaded from databases along with their parameters and rate equations. The modular network design can be used to exchange modules as well as test the concept of modularity in biological systems. The flexible modeling framework along with the C and Python API allows TinkerCell to serve as a host to numerous third-party algorithms. TinkerCell is a free and open-source project under the Berkeley Software Distribution license. Downloads, documentation, and tutorials are available at www.tinkercell.com.Comment: 23 pages, 20 figure

    Chromogranin A in neurons of the rat cerebellum and spinal cord: quantification and sites of expression

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    Chromogranin A (CGA) is an abundant protein of dense-cored secretory vesicles in endocrine and neuronal cells. The present study, for the first time, compares CGA of neurons of the central nervous system with the CGA of adrenal origin. By S1 nucleus protection assay, we found that the 3' part of the CGA mRNA between exons 5-8 of the cerebellum and the spinal cord of the rat is homologous to that of the adrenal. In situ hybridization histochemistry revealed that CGA mRNA in the cerebellar cortex is present in cell bodies of Purkinje cells and in neurons of the deep cerebellar nuclei. The perikarya of these cells also exhibit CGA-like immunoreactivity. CGA mRNA and CGA-like immunoreactivity are also present in the motoneurons of the ventral, lateral, and dorsal horns of the rat spinal cord. The amounts of CGA, as determined by radioimmunoassay in cerebellum and spinal cord, were about one tenth of the amounts detected in the adrenal, adenohypophysis, or the olfactory bulb. The sites of CGA expression suggest that CGA may be involved in signal transduction in the motor system

    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
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