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  • 2000-2004  (10)
  • 1985-1989  (10)
  • 1980-1984  (15)
  • 1935-1939  (1)
  • 1
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 756-763 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We report angle-resolved measurements of vi=0 → vf=1 vibrational transitions in Na2–He collisions at an energy of 90 meV. The agreement with calculated cross sections using an ab initio surface is good, both in the angular variation of the cross section as well as with respect to its magnitude relative to the vibrationally elastic process. The calculated (vi=0, ji=0) → (vf=1, jf ) differential cross sections are discussed in some more detail. They show structure, in addition to the rainbow oscillations, related to the fact that the vibrational transition probability vanishes for a specific approach angle.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 2680-2684 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: Differential cross sections for rotational transitions in Na2–Ne, Ar collisions are measured up to very large Δj. It is shown that the energy dependent anisotropy ΔR(E) of the interaction potential can be determined from these data using simple classical relations of ΔR and the rainbow angle θR. Excellent agreement with ab initio data is demonstrated and underlines the usefulness of this concept.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 2685-2688 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We report the resolution of supernumerary rotational rainbows for rotationally inelastic ji → jf=0 transitions in Na2–He, Ne, Ar scattering. The relation of the angular position of the supernumerary maxima and the anisotropy ΔR of the interaction potential is established. The analysis yields the energy dependent anisotropy ΔR(E) in very good agreement with data from other sources.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 286-302 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We describe a technique for preparation of molecules in single ||m|| levels involving saturated laser optical pumping on molecular P, R, and Q transitions. This technique is not limited to small rotational quantum numbers j. It allows the determination of the populations of ||m|| levels for arbitrary distribution functions f ( j,m) or alternatively, the determination of all moments of f ( j,m). In principle, this method is able to completely determine the angular distribution of j vectors. Experimental verification of the high ||m||-state purity achieved in Na2 supersonic beams, as well as of inherent limitations due to hyperfine interaction is provided. For illustration, experimental data on laser-induced alignment, the dependence of the flow induced molecular alignment, and on Δm-propensity rules in differential rotationally inelastic scattering are presented.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 2583-2584 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: A significant increase in the total integral cross section in (Na)2−Ne collisions with the vibrational level v'' of the sodium molecule in the electronic ground state, at a collision energy of the order of 1 mev is reported. (AIP)
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 534-546 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: 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.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 5064-5076 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We report the successful application of an optically pumped molecular beam laser for efficient and selective population transfer from v″=0 to high lying vibrational levels of Na2 in the electronic ground state. More than 50% of the molecules in a thermally populated rotational level of v″=0 can be transferred to a state v″(very-much-greater-than)1 with typically ≥75% of the molecules excited out of the initial state found in the predetermined end vibrational level and approximately ≤25% distributed over other levels according to the Franck–Condon factors. The applicability of this technique to the study of collision processes involving vibrationally highly excited levels is discussed. This work also contributes in general to a better understanding of optically pumped dimer lasers.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 13 (1983), S. 0 
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Precipitins against avian antigens in sera from patients with extrinsic allergic alveolitis, asymptomatic pigeon and chicken breeders and from control individuals were tested with different antigen extracts in six laboratories by a variety of different methods. Eighty percent of the results coincided in identifying the positive sera from patients and 90% in identifying the controls. It seems possible therefore to exchange results among experienced laboratories with fair confidence.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science, Ltd
    Clinical & experimental allergy 32 (2002), S. 0 
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Background The results of numerous studies on the influence of breastfeeding in the prevention of atopic disorders are often contradictory. One of the most important problems is confounding by other lifestyle factors.Objective The aim of the present study was to analyse the effect of any breastfeeding duration on the prevalence of atopic eczema in the first seven years of life taking into account other risk factors.Methods In an observational birth cohort study 1314 infants born in 1990 were followed-up for seven years. At 3, 6, 12, 18, 24 months and every year thereafter, parents were interviewed and filled in questionnaires, children were examined and blood was taken for in vitro allergy tests. Generalized Estimation Equations (GEE)-models were used to model risk factors for the prevalence of atopic eczema and for confounder adjustmentResults Breastfeeding was carried out for longer if at least one parent had eczema, the mother was older, did not smoke in pregnancy, and the family had a high social status. The prevalence of atopic eczema in the first seven years increased with each year of age (OR 1.05; 95% CI 1.01–1.09 for each year), with each additional month of breastfeeding (1.03; 1.00–1.06 for each additional month), with a history of parental atopic eczema (2.06; 1.38–3.08), and if other atopic signs and symptoms appeared, especially specific sensitization (1.53; 1.25–1.88), and asthma (1.41; 1.07–1.85). Although breastfeeding should be recommended for all infants, it does not prevent eczema in children with a genetic risk.Conclusion Parental eczema is the major risk factor for eczema. But in this study, each month of breastfeeding also increased the risk
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford BSL : Blackwell Science Ltd
    Clinical & experimental allergy 30 (2000), S. 0 
    ISSN: 1365-2222
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
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