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Head-space sampling (HS) has been combined with enantioselective gas chromatography (GC) for the analysis of chiral and non-chiral monoterpenes present in the cortical tissues of five different Norway spruce clones. (1S)-(-)-alpha-Pinene, (1S,5S)-(-)sabinene, (1S)-(-)-beta-pinene, and (4S)-(-)limonene dominated over (1R)-(+)-alpha-pinene, (1R,5R)-(+)-sabinene, (1R)-(+)-beta-pinene, and (4R)-(+)-limonene. Results showed a large variation in the enantiomeric composition of cortical tissues between different clones. The development of HS-GC greatly increased the speed of precise analyses of chiral monoterpenes in small samples and therefore offer excellent opportunities in studies on the ecophysiological and chemotaxomic roles of these chiral components.  相似文献   
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We measured isotope shifts and hyperfine structure of visible transitions of stable strontium isotopes by means of Doppler-free saturated absorption spectroscopy. In particular, we investigated transitions between excited states where the upper level involves two excited electrons. We report hyperfine coupling constants for the levels 5p4d1D2, 5p4d3F2, 5s4d3D1, 5s6s3S1, 5s5p3P1 and, for some of the studied transitions, we separate the specific mass and volume contribution to the isotope shifts.  相似文献   
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Summary In an important experiment performed on a SQUID system, Rouse, Han and Lukens report the first observation of resonant tunnelling between macroscopically distinct quantum levels. We support the experiment with the first theoretical approach for the phenomenon.  相似文献   
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Summary We study the effect of temperature on the lifetime of the resonant macroscopic quantum tunnelling voltage state. In view of experiments we consider a merit factor in order to balance between measuring extremely small signals of longer duration or larger signals of shorter duration.  相似文献   
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Summary The effect of dissipation in experiments on macroscopic quantum tunnelling in Josephson tunnel junctions are discussed. The frequency-dependent, nonlinear dynamic resistance of the junction makes it difficult to understand which effective linear resistance has to be chosen to compare the experimental results with the theory developed in the framework of the RSJ model. Various experiments reported in the literature lead to different conclusions and are presently discussed. Recently obtained experimental results on the thermal regime allow us to propose a new experimental strategy which ultimately should remove any ambiguity on the possibility to observe MQT process in the presence of dissipation in Josephson structures. To speed up publication, the authors have agreed not to receive proofs which have been supervised by the Scientific Committee.  相似文献   
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The status of the unitary triangle beyond the standard model including the most recent results on Deltam[s] on dilepton asymmetries and on width differences is presented. Even allowing for general new physics loop contributions the unitarity triangle must be very close to the standard model result. With the new measurements from the Fermilab Tevatron, we obtain for the first time a significant constraint on new physics in the Bs sector. We present the allowed ranges of new physics contributions to DeltaF=2 processes and of the time-dependent CP asymmetry in Bs-->J/psivarphi decays.  相似文献   
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