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  • Articles: DFG German National Licenses  (27)
  • 1995-1999  (16)
  • 1990-1994  (5)
  • 1985-1989  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Electron capture processes in optically excited In0.53Ga0.47As/InP quantum wells (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 933-935 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed picosecond time-resolved measurements on In0.53Ga0.47As/InP quantum wells with varying barrier thicknesses using 10 ps Nd:YAG excitation. For this excitation, holes and electrons are created in the In0.53Ga0.47As layers. Due to momentum conservation the Nd:YAG excitation accelerates the electrons above the InP barrier where they can diffuse but cannot recombine. By examining the rise time of the quantum well emission, we can show that for samples with thick barriers, the barrier geometry largely controls the dynamic properties of the carriers after Nd:YAG excitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101728
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Neuroactive steroids induce GABAA receptor-mediated depolarizing postsynaptic potentials in hippocampal CA1 pyramidal cells of the rat (1998)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 10 (1998), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Intracellular recordings were performed in area CA1 pyramidal cells of rat hippocampal slices to determine the effects of certain steroids on inhibitory postsynaptic potentials/currents (IPSP/Cs) mediated by GABAA receptors. Following application of the steroids 5α-pregnan-3α,21-diol-20-one (5α-THDOC), alphaxalone and 5β-pregnan-3α-ol-20-one (pregnanolone) hyperpolarizing PSPs developed into biphasic responses consisting of an early hyperpolarizing and a late depolarizing PSP sequence. Steroid-induced depolarizing PSPs could be elicited in the presence of antagonists to non-NMDA, NMDA, and GABAB receptors, indicating that these receptor types do not contribute significantly to the initiation of these responses. Depolarizing PSPs were completely blocked by both GABAA receptor antagonists bicuculline and t-butylbicyclophosphorothionat (TBPS) providing evidence for their mediation by GABAA receptors. The reversal potential of steroid-induced late inward PSCs, measured in single-electrode voltage clamp, was –29.9 ± 5.3 mV, whereas the early outward current, which corresponded to the early hyperpolarizing component of PSPs, reversed at –68.2 ± 1.5 mV. Depolarizing PSPs and late inward PSCs were sensitive to reduction of extracellular [HCO3–] and block of carbonic anhydrase by application of acetazolamide. The results suggest that certain neuroactive steroids can induce GABAA receptor-mediated depolarizing PSPs, which are dependent on HCO3–.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1998.00297.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Electrical coupling underlies high-frequency oscillations in the hippocampus in vitro (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 394 (1998), S. 189-192 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Coherent oscillations, in which ensembles of neurons fire in a repeated and synchronous manner, are thought to be important in higher brain functions. In the hippocampus, these discharges are categorized according to their frequency as theta (4–10 Hz), gamma (20–80 Hz) ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/28184
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  • 4
    Electronic Resource
    Electronic Resource
    Wafer and epilayer improvement for integrated optics devices on InP: the ESPRIT project 2518 (1991)
    Springer
    Optical and quantum electronics 23 (1991), S. 391-404 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Ga x In1−x As y P1−y alloys lattice matched to InP substrates are currently used to fabricate optoelectronic and integrated optics devices. To achieve devices with high performances and high fabrication yield, the uniformity and reproducibility of the Ga x In1−x As y P1−y epitaxial layers (composition, thickness, doping, etc.) have become key parameters. These problems have been addressed in the frame of ESPRIT project 2518 and are presented in this paper. Several aspects have been considered starting from the optimization of InP substrates, the MOVPE growth of uniform GalnAsP layers, the material characterization to the validation of material uniformity on passive optical waveguides. Both scanning photoluminescence analysis and waveguide losses measurements performed on 2 inch wafers with a high lateral resolution have shown that high quality uniform GalnAsP layers can be obtained reproducibly on 2″ InP substrates using a commercially available LP-MOCVD growth process. In particular, more than 60% of 36 mm long, 3μm wide and 100μm spaced rib waveguides exhibit losses below 0.8dBcm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619612
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    A study of 3-jet events ine + e − annihilation into hadrons at 34.6 GeV c.m. energy (1985)
    Springer
    The European physical journal 29 (1985), S. 29-40 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Three-jet events produced bye + e − annihilation into hadrons at 34.6 GeV c.m. energy were studied by comparing them with 2nd order QCD and two different models of fragmentation. The distribution of low energy particles in the 3-jet plane is found to be better described by the LUND color string model than by the independent jet model. The opposite is true for more energetic particles flowing between the 3 jets. The average transverse momenta in jets can be described with values of σ q between 350 and 500 MeV/c for the gluon jet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01571375
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    Paper (German National Licenses)
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  • 6
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    Unknown
    Diane B. Kunz, ed. "American Foreign Relations During the 1960s" (Book Review) (1995)
    Kingston, R.I., etc. : Periodicals Archive Online (PAO)
    The Historian. 57:4 (1995:Summer) 803 
    Details
    ISSN: 0018-2370
    Topics: History
    Description / Table of Contents: THE AMERICAS
    Notes: Book Reviews
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:3109-1995-057-04-000038
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  • 7
    Electronic Resource
    Electronic Resource
    The coupling of Cr to Fe studied by circular magnetic X-ray dichroism (1995)
    Springer
    Applied physics 61 (1995), S. 119-122 
    Details
    ISSN: 1432-0630
    Keywords: 78.70 ; 73.40 ; 75.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The coupling of Cr to Fe in stacked Cr/Fe/Cr trilayers is studied by circular magnetic X-ray dichroism using fluorescence yield to monitor the absorption. From the dichroic spectra, we determine the thickness dependent average magnetic coupling of Cr to Fe for Cr layer thicknesses of 1, 2 and 3 ML. We compare our results to new calculated spectra. Additionally, all Cr spectra show significant contributions due to photon scattering processes at theL 2, 3 absorption edges depending on the degree of circular polarization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01538376
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  • 8
    Electronic Resource
    Electronic Resource
    The coupling of Cr to Fe studied by circular magnetic X-ray dichroism (1995)
    Springer
    Applied physics 61 (1995), S. 119-122 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 78.70; 73.40; 75.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract.  The coupling of Cr to Fe in stacked Cr/Fe/Cr trilayers is studied by circular magnetic X-ray dichroism using fluorescence yield to monitor the absorption. From the dichroic spectra, we determine the thickness dependent average magnetic coupling of Cr to Fe for Cr layer thicknesses of 1, 2 and 3 ML. We compare our results to new calculated spectra. Additionally, all Cr spectra show significant contributions due to photon scattering processes at the L 2,3 absorption edges, depending on the degree of circular polarization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050177
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of methysticin on three different models of seizure like events studied in rat hippocampal and entorhinal cortex slices (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 348-355 
    Details
    ISSN: 1432-1912
    Keywords: Key words High potassium ; Ictaform events ; Low calcium ; Low magnesium ; Methysticin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Methysticin is one of the constituents of Piper methysticum which possesses anticonvulsant and neuroprotective properties. Its effects on different in vitro seizure models were tested using extracellular recordings in rat temporal cortex slices containing the hippocampus and the entorhinal cortex. Elevating [K+]0 induced seizure-like events with tonic and clonic electrographic phases in area CA1. Lowering [Ca2+]0 caused recurrent seizure like episodes with large negative field potential shifts. Lowering Mg2+ induced short recurrent discharges in area CA3 and CA1 while ictaform events lasting for many seconds were induced in the subiculum, entorhinal and temporal neocortex. In the hippocampus the activity stayed stable over a number of hours. In contrast, the ictaform events in the subiculum, entorhinal and temporal cortex changed their characteristics after one to two hours to late recurrent discharges. In a concentration-range from 10 to 100 μM methysticin reversibly blocked all these types of epileptiform activity. Decreases in [Ca2+]0 and associated slow field potentials evoked by repetitive stimulation of the stratum radiatum or the alveus remained almost unaffected by methysticin. A paired pulse stimulus paradigm used to test for effects of methysticin on synaptically evoked transient field potentials in normal medium revealed interference with mechanisms involved in frequency potentiation. While responses to alvear stimulation were largely unaffected, the responses to a paired pulse stimulus to stratum radiatum were depressed over the whole range of tested stimulus intervals. The findings suggest that methysticin has effects on different patterns of epileptiform activity possibly by interfering with processes responsible for frequency potentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169074
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of methysticin on three different models of seizure like events studied in rat hippocampal and entorhinal cortex slices (1995)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 351 (1995), S. 348-355 
    Details
    ISSN: 1432-1912
    Keywords: High potassium ; Ictaform events ; Low calcium ; Low magnesium ; Methysticin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methysticin is one of the constituents of Piper methysticum which possesses anticonvulsant and neuroprotective properties. Its effects on different in vitro seizure models were tested using extracellular recordings in rat temporal cortex slices containing the hippocampus and the entorhinal cortex. Elevating [K+]o0 induced seizure-like events with tonic and clonic electrographic phases in area CA1. Lowering [Ca2+]0 caused recurrent seizure like episodes with large negative field potential shifts. Lowering Mg2+ induced short recurrent discharges in area CA3 and CA1 while ictaform events lasting for many seconds were induced in the subiculum, entorhinal and temporal neocortex. In the hippocampus the activity stayed stable over a number of hours. In contrast, the ictaform events in the subiculum, entorhinal and temporal cortex changed their characteristics after one to two hours to late recurrent discharges. In a concentration-range from 10 to 100 μM methysticin reversibly blocked all these types of epileptiform activity. Decreases in [Ca2+]0 and associated slow field potentials evoked by repetitive stimulation of the stratum radiatum or the alveus remained almost unaffected by methysticin. A paired pulse stimulus paradigm used to test for effects of methysticin on synaptically evoked transient field potentials in normal medium revealed interference with mechanisms involved in frequency potentiation. While responses to alvear stimulation were largely unaffected, the responses to a paired pulse stimulus to stratum radiatum were depressed over the whole range of tested stimulus intervals. The findings suggest that methysticin has effects on different patterns of epileptiform activity possibly by interfering with processes responsible for frequency potentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169074
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    Paper (German National Licenses)
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