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  • 1
    Electronic Resource
    Electronic Resource
    Photoemission of spinpolarized electrons from strained GaAsP (1996)
    Springer
    Applied physics 63 (1996), S. 203-206 
    Details
    ISSN: 1432-0630
    Keywords: 79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10−3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01567651
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  • 2
    Electronic Resource
    Electronic Resource
    Lack of interaction between meloxicam and warfarin in healthy volunteers (1997)
    Springer
    European journal of clinical pharmacology 51 (1997), S. 421-425 
    Details
    ISSN: 1432-1041
    Keywords: Key words Warfarin ; Meloxicam ; interaction ; pharmacokinetics ; protein binding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The effect of multiple oral doses of meloxicam 15 mg on the pharmacodynamics and pharmacokinetics of warfarin was investigated in healthy male volunteers. Warfarin was administered in an individualized dose to achieve a stable reduction in prothrombin times calculated as International Normalized Ratio (INR) values. Then INR- and a drug concentration-time profile was determined. For the interaction phase, meloxicam was added for 7 days and then INR measurements and the warfarin drug profiles were repeated for comparison. Overall, warfarin treatment lasted for 30 days. Results: Warfarin and meloxicam were well tolerated by healthy volunteers in this study. Thirteen healthy volunteers with stable INR values entered the interaction phase. Prothrombin times, expressed as mean INR values, were not significantly altered by concomitant meloxicam treatment, being 1.20 for warfarin alone and 1.27 for warfarin with meloxicam cotreatment. R- and S-warfarin pharmacokinetics were similar for both treatments. Geometric mean (% gCV) AUCSS values for the more potent S-enantiomer were 5.07 mg · h · l−1 (27.5%) for warfarin alone and 5.64 mg · h · l−1 (28.1%) during the interaction phase. Respective AUCSS values for R-warfarin were 7.31 mg · h · l−1 (43.8%) and 7.58 mg · h · l−1 (39.1%). Conclusion: The concomitant administration of the new non-steroidal anti-inflammatory drug (NSAID) meloxicam affected neither the pharmacodynamics nor the pharmacokinetics of a titrated warfarin dose. A combination of both drugs should nevertheless be avoided and, if necessary, INR monitoring is considered mandatory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050224
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  • 3
    Electronic Resource
    Electronic Resource
    Measurements of the absolute external luminescence quantum efficiency in ZnSe/ZnMgSSe multiple quantum wells as a function of temperature (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6871-6876 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on a novel experimental setup using a miniature integrating sphere fitted into a cryostat to measure spectrally resolved the absolute external photoluminescence quantum efficiency ηlum in the temperature range from 6 K to beyond room temperature. Direct access to ηlum is achieved by an uncomplicated method to calibrate the spatially integrated emission spectra absolutely. The fraction of light coupled out of the sphere into the detection system is in good approximation independent of the emitted wavelength and the emission characteristics of the investigated samples, due to their smallness compared with the total sphere area. This fact is proved by theoretical calculations for the sphere throughput and the irradiance within the sphere. To demonstrate the capabilities of this setup, we investigate in high quality ZnSe/ZnMgSSe 10× multiple quantum wells, the temperature dependence of the quantum efficiency, simultaneously for the quantum well and the barrier luminescence. Within a thermal activation model, three processes are found to contribute to the thermal quenching of ηlum of the quantum well luminescence. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368982
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  • 4
    Electronic Resource
    Electronic Resource
    Pre-release assessment ofNanaia sp. [Lepidoptera: Phycitidae] fromOpuntia pascoensis for biological control ofOpuntia aurantiaca [Cactaceae] (1988)
    Springer
    BioControl 33 (1988), S. 81-86 
    Details
    ISSN: 1573-8248
    Keywords: Nanaia ; Opuntia ; biocontrol ; evaluation ; host-specificity ; Nanaia ; Opuntia ; lutte biologique ; évaluation ; spécificité vis-à-vis de l'hôte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Nanaia sp. a été récolté surOpuntia pascoensis Britton & Rose au Pérou et introduit en Afrique du Sud pour lutter biologiquement contreOpuntia aurantiaca Lindley. Depuis l'existence de cette nouvelle association Insecte-Plante, les chances d'une lutte biologique efficace pourraient être théoriquement augmentées. Cependant, les études de laboratoire avant lâcher montraient les effets adverses de l'élevage de laboratoire, le développement larvaire était plus lent, la survie larvaire était diminuée, des adultes plus petits apparaissaient et la reproduction était supprimée surO. aurantiaca par rapport àO. pascoensis. La nouvelle associationNanaia sp./O. aurantiaca ne sera probablement pas vouée au succès, bien que des essais de plein champ devraient être développés pour le confirmer, un vaste programme d'élevage et de lâcher serait une perte de temps et un gaspillage d'argent et d'effort.
    Notes: Abstract Nanaia sp. was collected onOpuntia pascoensis Britton & Rose in Peru and introduced into South Africa for biological control ofOpuntia aurantiaca Lindley. Since this is a new insect-plant association the chances of successful biological control could theoretically be enhanced. However, pre-release insectary studies showed that apart from the adverse affects of insectary rearing, larval development was slower, less larvae survived, smaller adults emerged and reproduction was suppressed onO. aurantiaca compareded toO. pascoensis. The new association ofNanaia sp. onO. aurantiaca will probably not succeed and, although field trials should be conducted to confirm this, an extensive mass-rearing and release programme would be a waste of time, finances and effort.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02372316
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence for stratospheric nitric acid condensation from balloon and rocket measurements in the Arctic (1989)
    [s.l.] : Nature Publishing Group
    Nature 342 (1989), S. 493-497 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Strong evidence for nitric acid condensation at altitudes of about 18–23 km is provided by balloon-and rocket-borne measurements made near Kiruna, northern Sweden, in January 1989. Nitric acid con-densation is believed to be a necessary step in the chemical pre-conditioning required for ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/342493a0
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  • 6
    Electronic Resource
    Electronic Resource
    The population dynamics of an introduced tree, Sesbania punicea, in South Africa, in response to long-term damage caused by different combinations of three species of biological control agents (1998)
    Springer
    Oecologia 114 (1998), S. 343-348 
    Details
    ISSN: 1432-1939
    Keywords: Key words Insect herbivory ; Host-plant density ; Perennial weed ; Biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper contributes to the relatively sparse literature on the effects of insect herbivory on the population dynamics of plants and is probably unique in that it reports the long-term effects of combinations of three insect herbivore species on the population densities of a moderately long-lived tree species. The tree is Sesbania punicea, a leguminous perennial from South America that has been the target of a biological control programme in South Africa for almost 20 years. Sixteen infestations of the weed have been monitored for periods of up to 10 years to determine changes in the density of the mature, reproductive plants under the influence of different combinations of three biological control agents (i.e. with one, two or three of the agent species present in the weed infestation). The three biological control agents, all weevil species, include Trichapion lativentre, which primarily destroys the flower-buds, Rhyssomatus marginatus, which destroys the developing seeds, and Neodiplogrammus quadrivittatus, whose larvae bore into the trunk and stems of the plants. While T. lativentre occurs throughout the range of the weed in South Africa, the other two species are less mobile, more recent introductions and are largely confined to the vicinity of selected release sites. There has been a significant decline in the density of mature S. punicea in areas where two or more of the agents are established. The decline of the weed has been most evident where N. quadrivittatus is active and particularly so where both of the other two weevil species are also present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050456
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  • 7
    Electronic Resource
    Electronic Resource
    First measurement of the polarisation transfer on the proton in the reactions $$H(\vec e,e'\vec p)$$ and $$D(\vec e,e'\vec p)$$ (1995)
    Springer
    The European physical journal 352 (1995), S. 211-214 
    Details
    ISSN: 1434-601X
    Keywords: 13.40.Fn ; 25.30.Bf
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The measurement of the polarisation transfer to the proton in the reactions $$H(\vec e,e'\vec p)$$ and $$D(\vec e,e'\vec p)$$ performed with longitudinally polarised electrons in quasi-free kinematics is presented. The coincidence measurement was executed atQ 2≈8fm −2 using the 855 MeV, c.w. beam of the Mainz Microtron MAMI. The recoil polarisation was determined by means of a carbon analyser. The experiment shows that the binding of the nucleon does not modify the polarisationP x of the recoil proton within an error ofΔ P x/Px≈10%. The measured polarisation agrees with recent theoretical predictions. Implications for the measurement of the electric form factor of the neutron using the $$D(\vec e,e'\vec n)$$ reaction are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01298910
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  • 8
    Electronic Resource
    Electronic Resource
    Rapid communication Photoemission of spinpolarized electrons from strained GaAsP (1996)
    Springer
    Applied physics 63 (1996), S. 203-206 
    Details
    ISSN: 1432-0630
    Keywords: PACS79.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Strained layer GaAs $_{.95}$ P $_{.05}$ photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P $^2 \times $ QE = 2.3 $\times 10^{-3}$ is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around $830\;{\rm nm}$ is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. AaAs $_{.55}$ P $_{.45}$ –GaAs $_{.85}$ P $_{.15}$ superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by anarsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01567651
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of the neutron electric form factor in the D(e,e′n)p reaction and the influence of nuclear binding (1999)
    Springer
    The European physical journal 5 (1999), S. 131-135 
    Details
    ISSN: 1434-601X
    Keywords: PACS: 25.30.Fj Nuclear Reactions: Inelastic electron scattering to continuum – 14.20.Dh Properties of Specific Particles: Protons and neutrons – 13.40.Gp Electromagnetic form factors – 25.10.+s Nuclear reactions involving few–nucleon systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The electric form factor of the neutron G E,n has been determined at the Mainz Microtron MAMI at the low momentum transfer Q 2= 0.15 (GeV/c)2 in a measurement of the recoil polarisation ratio P x/Pz in the quasifree reaction D(e,e′n)p. At this Q 2 the influence of the nuclear binding is strong. A purely kinematical model is used to get some insight into the effect of the initial Fermi momentum distribution of the neutron. The influence of the final state interaction is determined quantitatively by a model of Arenhövel et al.. After the corresponding corrections a value of G E,n(0.15 (GeV/c)2) = 0.0481±0.0065stat±0.0053syst is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050268
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of the neutron electric form factor from the reaction 3 He(e,e'n) at medium momentum transfer (1999)
    Springer
    The European physical journal 6 (1999), S. 329-344 
    Details
    ISSN: 1434-601X
    Keywords: PACS: 14.20.Dh Properties of specific particles: Protons and neutrons – 24.70.+s Nuclear reactions: Polarization phenomena in reactions – 13.40.Gp Specific reactions and phenomenology: Electromagnetic form factors – 25.10.+s Nuclear reactions involving few–nucleon systems – 25.30.Fj Nuclear reactions: Inelastic electron scattering to continuum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The electric form factor of the neutron GEn has been determined in double polarized exclusive 3 He(e,e'n) scattering in quasi–elastic kinematics by measuring asymmetries A ⊥, A ∥ of the cross section with respect to helicity reversal of the electron, with the nuclear spin being oriented perpendicular to the momentum transfer q in case of A⊥ and parallel in case of A∥. The experiment was performed at the 855 MeV c. w. microtron MAMI at Mainz. The degree of polarization of the electron beam and of the gaseous 3 He target were each about 50%. Scattered electrons and neutrons were detected in coincidence by detector arrays covering large solid angles. Quasi–elastic scattering events were reconstructed from the measured electron scattering angles ϑe, φe and the neutron momentum vector p n ′ in the plane wave impulse approximation. We obtain the result 〈G En〉(0.27 〈 Q2c2/GeV2 〈 0.5)= 0.0334 ± 0.0033stat± 0.0028syst which is averaged over the indicated range of Q 2, the squared momentum transfer. This G En value is significantly smaller than measured from the D(e,e'n) reaction under similar kinematical conditions. To what extent final state interactions in 3He quench the G En result is subject of calculations currently in progress elsewhere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050351
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