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  • 33.40.Hp  (3)
  • seasonality  (2)
  • 3320K  (1)
  • 1
    ISSN: 1570-7458
    Keywords: Bruchidius uberatus ; Acacia nilotica ; egg-hatching ; development ; seasonality ; seed predation ; seed storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Der Lebenszyklus des Samenkäfers Bruchidius uberatus in Samen von Acacia nilotica wurde unter Feld- und Laborbedingungen untersucht. Im Gegensatz zu multivoltinen Populationen im Sudan (Peake, 1982) sind die Populationen von B. uberatus in Botswana vor allem univoltin. Adulte Käfer verlassen die Samen von A. nilotica während des Süd-Frühlings (Oktober/November). Im Spätsommer (Februar/März) geschlüpfte Käfer entstammen multivoltinen Genotypen, wie Züchtungsexperimente gezeigt haben. Die reproduktive Aktivität der Weibchen wird nicht durch die Zufuhr von Pollen oder Zucker stimuliert. Die Entwicklungsdauer vom Ei bis zum 1. Larvenstadium beträgt 15 Tage bis 52 und 3 bis 11 Monate bis zum adulten Käfer, deren Lebenserwartung unter Laboratoriumbedingungen 4 bis 40 Tage beträgt. Hierbei besteht kein Unterschied zwischen uni- und multivoltinen Käfern. Der lange Lebenszyklus in Botswana steht im Gegensatz zu dem 40-tägigen Lebenszyklus von B. uberatus im Sudan, der offensichtlich durch die Jahrhunderte andauernde Sammlung von Früchten verursacht ist. Samenvorräte, die zu Forstzwecken längere Zeit aufbewahrt werden, können innerhalb von 5 bis 8 Jahren völlig zerstört werden. Dabei ist die Wirtsspezifität gering. Die Infektion betrifft auch andere Acacia-Arten, z.B. A. burkei, A. erioloba, A. hebeclada, A. mellifera, A. robusta und A. tortilis. Durch die rasche Zerstörung der Embryoachse haben die Käfer keinen positiven Einfluss auf die Keimung dieser hartschaligen Acacia-Samen.
    Notes: Abstract The life cycle of the bruchid beetle Bruchidius uberatus in seeds of Acacia nilotica has been investigated under field and laboratory condition. In contrast to the multivoltine populations in the Sudan, in Botswana most beetles of B. uberatus are univoltine. They emerge from the seed and pod in early spring (October to November). Only a small part of the population, which emerge in late summer (February to March) is multivoltine, as confirmed by rearing experiments. The reproductive activity of females is not stimulated by pollen, as found in feeding experiments. Minimum life-span of adult beetles varies between 4 and 40 days, but it did not differ between univoltine and multivoltine beetles. Other data on life-history are 22 days for hatching of the fist-instar larva at a temperature regime of 20/15 °C (day/night) and 15 days at a temperature regime of 32/15 °C and 3 to 11 months for development from larvae to beetle. During dry storage of seeds B. uberatus can destroy the total amount of stored seeds within a few years. In stored seed pool, host-specificity of larva is low. The life cycles of the Botswana population have been discussed in relation to that of the species in the Sudan.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 30 (1983), S. 105-108 
    ISSN: 1432-0649
    Keywords: 33.40.Hp ; 35.80.+s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hyperfine components in theN=1←0 rotational transition of theX 2Σ state of SrF have been studied with microwave-optical polarization spectroscopy. Of particular interest was the examination of the line shape under the influence of various microwave intensities, cell pressures and small magnetic fields below 1 G. Compensation of the earth's magnetic field with external Helmholtz coils resulted in line widths as small as 600 kHz.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0649
    Keywords: 35.80.+s ; 33.40.Hp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A laser-microwave double-resonance experiment has been developped basing on the principle of the known laser-rf double-resonance technique. This novel beam experiment allows high-resolution measurements of rotational transitions in a molecular ground state. The method was applied to the high-temperature radical CaCl to study the hyperfine structure of transitions between low-lying rotational states. Microwave scans yielded linewidths of 15–20 kHz limited only by time-of-flight broadening and residual Zeeman splitting.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 48 (1989), S. 463-466 
    ISSN: 1432-0649
    Keywords: 3320K ; 4272
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The hyperfine structure of various absorption lines of molecular iodine with wavenumbers between 12980 and 13890 cm−1 has been resolved using Doppler-free polarization spectroscopy. The wavenumbers of theo-component of 17 rovibrational lines of I2 due to the transitionB 3Π ou + −X1∑ g + with even rotational quantum numbers have been determined with an accuracy of 0.001 cm−1. A comparison of the centers of gravity of these 17 lines with the values of the iodine atlas of Gerstenkorn et al. yields a difference of $$\delta \tilde v = \tilde v_{c.g} - \tilde v_{atl} = - (1.8 \pm 1.2)x 10 - 3 cm^{ - 3}$$ thus corroborating the data of the iodine atlas in the red region within limits of error.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5036
    Keywords: Agrostis capillaris ; heavy metals ; macro- and micro-nutrients ; natural populations ; seasonality ; VAM-infection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three populations of the perennial grass Agrostis capillaris, growing on limestone derived clay with and without natural enrichment of the heavy metals cadmium, lead, and zinc, and on a sandy soil polluted by a metal smelter have been investigated with regard to the percentage and seasonality of infection with vesicular-arbuscular mycorrhizal (VAM) fungi and its impact on mineral nutrition. In all populations VAM infection was lowest during winter, and highest during late summer and autumn. The population at the metal smelter site was less infected by VAM fungi than both other populations. The concentration of mineral nutrients for the three populations was clearly related to the soil concentration, but hardly modified by the degree of VAM infection.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 1 (1986), S. 103-112 
    ISSN: 1434-6079
    Keywords: 33.40.Hp ; 33.20.Kf ; 35.20.Sd
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Microwave optical polarization spectroscopy has been used to measure the hyperfine structure in theX 2 Σ + (v=0) electronic ground state of Sr79Br and Sr81Br. Optical hyperfine structure in theB 2 Σ +−X 2 Σ + (0,0) system was resolved by Doppler-free laser polarization spectroscopy. The magnetic hyperfine parametersb andc and the electricquadrupole hfs parametereqQ were determined for theX 2 Σ + andB 2 Σ + states of both molecules. The magnetic hfs has been interpreted as an effect of halide electron spin polarization. The electric quadrupole coupling constants are compared with the alkali halides and discussed in terms of Sternheimer antishielding in polar molecules.
    Type of Medium: Electronic Resource
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