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  • 1990-1994  (33)
  • 1975-1979  (3)
  • 11
    ISSN: 1434-6052
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract We have measured theR value in non-resonante + e − annihilation using the ARGUS detector at the storage ring DORIS II. At a centre-of-mass energy $$\sqrt s = 9.36$$ GeV the ratio of the hadronic cross-section to the μ-pair cross section in lowest order QED has been determined to beR=3.46±0.03±0.13. In addition, we have measured the charged-particle multiplicities in non-resonant hadron production at $$\sqrt s = 10.47$$ GeV just below theB $$\bar B$$ threshold and in ϒ (4S) resonance decays. For the average charged-particle multiplicities in continuum events and ϒ(4S)→B $$\bar B$$ decays we obtain 〈n〉cont=8.35±0.02±0.20 and 〈n〉ϒ(4s)=10.81±0.05±0.23.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 51 (1990), S. 91-93 
    ISSN: 1432-0649
    Schlagwort(e): 42.55.Gp ; 42.60.Da
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A KrF excimer laser was operated on two independently tunable lines. This was achieved by a double-resonator configuration with two gratings. Tuning range and gain competition were investigated. The narrow line width (〈1 cm−1) and the independent tunability make this laser ideal for simultaneous spectroscopic detection of two species and temperature measurements in combustion processes.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 54 (1992), S. 109-112 
    ISSN: 1432-0649
    Schlagwort(e): 82.50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Three schemes for imaging OH with tunable excimer lasers are compared: Excitation and detection at 308 nm (0–0 band, XeCl laser), excitation with a KrF laser at 248 nm (3–0 band) and a new scheme using excitation at 308 nm and detection at 343 nm (0–1 band). Each scheme has certain advantages: The first scheme gives by far the highest signal, the second is less sensitive to collisional quenching and the third is suited to dirty environments because of the long excitation wavelength and off-resonance detection.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 52 (1991), S. 341-346 
    ISSN: 1432-0649
    Schlagwort(e): 42.60 ; 34.50
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Saturation of two-dimensional laser-induced fluorescence is demonstrated using the coincidence between the strong 0–0 vibrational transition of OH around 308 nm and the emission of a tunable XeCl excimer laser. The 2D images were insensitive to variations in the laser power, implying reduced sensitivity to quenching processes. The ratio of the 2D images in the linear and saturated regimes show two-dimensional variations in the saturation intensity. Since saturation intensity is proportional to the quenching rate, this novel method allows one to check for variations in collisional lifetimes across the flame.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Archive of applied mechanics 60 (1990), S. 507-517 
    ISSN: 1432-0681
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Beschreibung / Inhaltsverzeichnis: Summary The plane stress and displacement field around the elliptical hole of an anisotropic linear elastic plate under arbitary orientation of tension force and fibres is analytically determined by the method of stress functions of a complex variable. For this purpose the infinite plate under uniaxial tension is used as mathematical model. For the example of glass fibre reinforced plastics with orthotropic properties it is shown that the data gathered from isotropic materials on the behaviour of stress and displacement around elliptical and circular holes are not applicable to anisotropic materials. This is especially true when load and orthotropic principal directions (off-axis-load) diverge. For several particular cases, the hole stress concentration factors which are decisive for the design are depicted in polar diagrams. The position of the maximum stress is also given which — in contrast to isotropic materials — generally no longer coincides with the notch base.
    Notizen: Übersicht Für die anisotrope linear-elastische Scheibe unter beliebiger Zugkraft- und Faserorientierung wird analytisch das ebene Spannungs- und Verschiebungsfeld um die elliptische Innenkerbe mittels komplex-wertiger Spannungsfunktionen ermittelt. Dabei dient als mathematisches Modell der (gezogene) Scheibenstreifen unendlicher Breite. Am Beispiel orthotrop glasfaserverstärkter Werkstoffe wird gezeigt, daß die vom isotropen Werkstoff her bekannten Aussagen über das Spannungs- und Verschiebungsverhalten an elliptischen und kreisförmigen Kerben auf anisotrope Werkstoffe nicht übertragbar sind. Insbesondere gilt dies bei Auseinanderklaffen von Last- und Orthotropiehauptrichtung (off-axis-Belastung). Für einige ausgezeichnete Fälle werden die für die Dimensionierung maßgebenden Spannungsüberhöhungsfaktoren in Polardiagrammen dargestellt sowie der Ort der maximalen Spannungsüberhöhung angegeben, der — im Unterschied zum isotropen Werkstoff — i. allg. nicht mehr mit dem Kerbgrund zusammenfällt.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 16
    ISSN: 1432-1114
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract A new method for the determination of the velocity field with all three velocity components in a light sheet was demonstrated that combines conventional particle tracking anemometry (PTA) with an intensity analysis of the particle flecks. The correlation between intensity and the dimension perpendicular to the light sheet was obtained from the monotonous variation of the laser light intensity across the width of the light sheet.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 98 (1994), S. 234-234 
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Biology and fertility of soils 15 (1993), S. 301-307 
    ISSN: 1432-0789
    Schlagwort(e): Mesofauna ; Amino sugar ; Soil micro-flora ; Beech forest ; Moder ; Lime
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary In December 1988, litter bags (mesh size: 45 and 1000 μm) were exposed in the organic layer of unlimed and limed moder soil under beech forest in the Solling area of Germany. Bags were retrieved on three sampling dates (May, September, and November 1989) and amounts (g m-2) of glucosamine and galactosamine were determined. Horizon-specific differences generally explained by far the largest part of the treatment variance. In the substrate sampled in December 1988 from the unlimed area glucosamine increased by a factor of 11.8 from the L 1 layer to the H layer and galactosamine by a factor of 15.9. With the exception of the F2 layer, the hexosamine amounts found in the limed substrate sampled in December 1988 were higher in all horizons than in the corresponding horizons sampled from the unlimed area. Exclusion of mesofauna from the 45-μm litter bags generally reduced the level of amino sugars at both sites. The difference between the two mesh sizes was most pronounced in the lowermost horizons (F2 and H) and quite small in the upper horizons. The exclusion of mesofauna significantly increased the glucosamine: galactosamine ratio in the two L layers of the unlimed soil on all sampling dates. Seasonal fluctuations suggested that the actual amino sugar content of the organic layer was essentially the function of two components, the first reflecting long-term accumulation of microbial metabo-lites, and the second reflecting short term fluctuations in the microbial colonization of various C sources together with spatial and temporal differences in the ability of the microflora to produce and to decompose hexosamines. The results of this study show that the mesofauna in the beech forest soils investigated significantly affected both the amino sugar components measured, and thus stimulated the accumulation of one of the most important N pools in forest soils.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 167 (1990), S. 771-784 
    ISSN: 1432-1351
    Schlagwort(e): Ontogeny ; Audition ; Vocalisation ; Sensorimotor interaction ; Rhinolophus rouxi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Horseshoe bats (Rhinolophus rouxi) were deafened in their 3rd–5th postnatal week. Subsequently their vocalisations were monitored to evaluate the impact of audition on the development of echolocation pulses. Hearing impairment affected the echolocation pulses as follows: the frequency of the constant frequency (CF) component was altered by between + 4 kHz and − 14 kHz, and the dominance of the second harmonic of the pulses was neutralised by a relative increase in intensity of the first and third harmonics. A second experiment focused on possible influences of acoustical self-stimulation with echolocation pulses on the establishment of auditory fovea representation in the inferior colliculus (IC). Frequency control of echolocation pulses was disrupted by larynx denervation. Thereafter, the bats produced multiharmonic echolocation signals (4–11 harmonics) varying in frequency. IC tonotopy, however, as monitored by stereotaxic electrophysiology, showed the same developmental dynamics as seen in control specimens (Fig. 10). Both experiments indicate that throughout postnatal development echolocation pulses are under auditory feedback control, whereas maturation of the auditory fovea and shifts in its frequency tuning represent an innate process. The significance of this postnatal development might be the adjustment of the vocal motor system of each bat to the frequency of its ‘personal’ auditory fovea.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 167 (1990), S. 757-769 
    ISSN: 1432-1351
    Schlagwort(e): Ontogeny ; Auditory fovea ; Tonotopy ; Sexual dimorphism ; Rhinolophus rouxi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary This report describes the ontogenesis of tonotopy in the inferior colliculus (IC) of the rufous horseshoe bat (Rhinolophus rouxi). Horseshoe bats are deaf at birth, but consistent tonotopy with a low-to-high frequency gradient from dorsolateral to ventromedial develops from the 2nd up to the 5th week. The representation of the auditory fovea is established in ventro-mediocaudal parts of the IC during the 3rd postnatal week (Fig. 3). Then, a narrow frequency band 5 kHz in width, comprising 16% of the bat's auditory range, captures 50–60 vol% of the IC (Fig. 3c). However, foveal tuning is 10–12 kHz (1/3 octave) lower than in adults; foveal tuning in females (65–68 kHz) is 2–3 kHz higher than in males (62–65 kHz). Thereafter, foveal tuning increases by 1–1.5 kHz per day up to the 5th postnatal week, when the adult hearing range is established (Figs. 4, 5). The increase of sensitivity and of tuning sharpness of single units also follows a low-to-high frequency gradient (Fig. 6). Throughout this development the foveal tuning matches the second harmonic of the echolocation pulses vocalised by these young bats. The results confirm the hypothesis of developmental shifts in the frequency-place code for the foveal high frequency representation in the IC.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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