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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 534-546 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We demonstrate and analyze a novel scheme for complete transfer of atomic or molecular population between two bound states, by means of Stark-chirped rapid adiabatic passage (SCRAP). In this two-laser technique a delayed-pulse laser-induced Stark shift sweeps the transition frequency between two coupled states twice through resonance with the frequency of the population-transferring coupling laser. The delay of the Stark-shifting pulse with respect to the pulse of the coupling-laser Rabi frequency guarantees adiabatic passage of population at one of the two resonances while the evolution is diabatic at the other. The SCRAP method can give a population-transfer efficiency approaching unity. We discuss the general requirements on the intensity and timing of the pulses that produce the Rabi frequency and, independently, the Stark shift. We particularly stress extension to a double-SCRAP technique, a coherent variant of stimulated emission pumping in the limit of strong saturation. We demonstrate the success of the SCRAP method with experiments in metastable helium, where a two-photon transition provides the Rabi frequency. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford BSL : Blackwell Science Ltd
    Clinical & experimental allergy 30 (2000), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Allergic diseases are more prevalent in affluent countries, which has been attributed to life-style factors. Life-style habits may also differ between socioeconomic (SES) classes. The objective of this paper therefore was to evaluate if SES had an impact on the development of atopic disorders.〈section xml:id="abs1-2"〉〈title type="main"〉MethodsA total of 1314 German children were followed-up in an observational birth cohort study to 6 years of age. Parents filled in questionnaires, and had multi-allergen screening tests for sensitization. Indoor allergen concentrations were determined by ELISA. Children were examined regularly up to 6 years, specific serum IgE values were determined by CAP-Rast-Feia.〈section xml:id="abs1-3"〉〈title type="main"〉ResultsThe risk of aeroallergen sensitization (odds ratio 1.76; 95% CI 1.30–2.37), and the lifetime prevalence of hay fever (2.36; 1.76–3.17), and asthma (1.74; 1.08–2.80), but not of atopic dermatitis (AD: 0.90; 0.54–1.51) was elevated in parents of high compared to low SES. With high SES the risk of smoking in pregnancy (0.35; 0.23–0.51), in the home (0.31; 0.21–0.46), pet ownership (0.37; 0.26–0.55), high mite (0.42; 0.25–0.74), and high cat (0.38; 0.18–0.82) allergen concentration in house dust was reduced, but elevated for breastfeeding over more than 6 months (4.67; 2.9–7.48). In children, even after controlling for other risk factors, only the risk of AD from 3 to 6 years (2.42; 1.42–4.14) was elevated in families with high SES, but not of AD in infancy or of any other atopic disorder.〈section xml:id="abs1-4"〉〈title type="main"〉ConclusionsWhile parents of high SES have a higher prevalence of inhalative allergies, their favourable life-style prevents the development of atopic disorders in their children, except for AD beyond infancy.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Copenhagen : Munksgaard International Publishers
    Allergy 55 (2000), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 10 (2000), S. 247-257 
    ISSN: 1434-6079
    Keywords: PACS. 33.15.Mt Rotation, vibration, and vibration-rotation constants - 33.20.Kf Visible spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Improved molecular constants for the and states of the NaH molecule are presented. NaH molecules are produced by reactive scattering of H and Na2 in a crossed beam experiment. High vibrational levels (6 9) of the NaH molecules are predominantly populated. Their excitation spectrum in the range has been measured using a new variant of Doppler spectroscopy. The transition frequencies involving the vibrational levels 2 8 in the and 6 9 in the state have been determined with an accuracy of better than . Using also previously published data a new set of molecular constants for the and state is derived. In particular, the vibrational dependence of the rotational constants B, D and H as well as some of v”-v' band origins for and is determined. The transition frequencies measured here or published previously are reproduced by these new coefficients with an accuracy of 0.1 cm-1 [rms value] with a maximum deviation of 0.4 cm-1. New RKR potential energy curves have been calculated up to the turning points of the levels v” = 9 in the state and v' = 25 in the state.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 8 (2000), S. 443-449 
    ISSN: 1434-6079
    Keywords: PACS. 42.50.Hz Strong-field excitation of optical transitions in quantum systems; multi-photon processes; dynamic Stark shift - 32.80.Wr Other multiphoton processes - 32.80.Bx Level crossing and optical pumping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: In traditional schemes of multilevel multilaser excitation, each laser pulse interacts with only one pair of states, and the rotating wave approximation (RWA) is applicable. Here we study the population transfer process in a three-state system when each of the two lasers interacts with each of the pair of states and when the Rabi frequencies characterizing the interaction strengths of the system are comparable to or larger than the difference of the transition frequencies. We show that complete and robust population transfer is possible under conditions more general than those hitherto considered necessary for stimulated Raman adiabatic passage (STIRAP) or for successive pulses. Using adiabatic Floquet theory we show that successful population transfer can be interpreted as adiabatic passage by means of a transfer state which connects the initial and final states. The Floquet picture offers a convenient interpretation of the population transfer as accompanied by multiple absorption of photons from or emission into the laser fields.
    Type of Medium: Electronic Resource
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