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  • 1
    ISSN: 1570-7458
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'examen a porté sur l'influence de différentes températures constantes sur le développement et la biologie imaginale de trois espèces prédatrices (Chrysopa sp., peut-être C. signata, Micromus tasmaniae et Nabis capsiformis) récoltées dans des champs de coton du sud-est du Queensland en Australie. C. sp. et N. capsiformis ont besoin respectivement de 335° au dessus d'un seuil de 10.5° et de 325° au dessus d'un seuil de 11.3°, pour se développer de l'oeuf à l'adulte. Les larves de M. tasmaniae pouvant effectuer la totalité de leur dévelopment a 5°.-A 23° les longévités des femelles adultes et les taux de ponte de C. sp. et N. capsiformis sout en moyenne de 52 j. (maximum 83) et 30 j. (maximum 43) d'une part et 18.1 et 10.4 œufs par jour d'autre part. Le taux de ponte de M. tasmaniae est de 19,1 œufs par jour pendant 5 semaines à 23°. La longévité réduite et le taux de ponte accru aux températures supérieures sont interprétés en basant la biologie imaginale sur le temps physiologique au dessus des seuils de développement. Les taux d'accroissement intrinsèque (rm) sont plus élevés aux températures élevées, principalement à la suite du taux de développement accru. M. tasmaniae possède le rm le plus élevé à toutes les températures par suite d'un développement rapide et de seuils thermiques bas, d'une brève période précédant la ponte et d'une date de ponte maximum précoce. Le rm de C. sp. est plus élevé que celui de N. capsiformis à la suite de son taux de ponte plus élevé. Les valeurs de rm fixées à partir du temps physiologique sont respectivement: 9,820, 6.868 et 8,366 œufs femelles/103 d° au dessus des seuils de 10,5°, -2,9° et 11,3° pour C. sp., M. tasmaniae et N. capsiformis.
    Notes: Abstract Immature Chrysopa sp. and Nabis capsiformis required 335 and 325 d°, respectively, for development from egg to adult, while larvae of Micromus tasmaniae were able to complete development at 5°. Mean adult female longevity and oviposition rate at 23° were 52 d (max. 83 d) and 18.1 eggs/d, and 30 d (max. 43 d) and 10.4 eggs/d for C. sp. and N. capsiformis respectively, and oviposition rate of M. tasmaniae averaged 19.1 eggs/d during 5 weeks. Reduced longevity and increased oviposition rate at higher temperatures were accounted for by basing adult biology on physiological time above the immature developmental thresholds. Intrinsic rates of increase were thus calculated as 9.820, 6.868, and 8.366 ♀ eggs/103 d° above thresholds of 10.5°, -2.9°, and 11.3° for C. sp., M. tasmaniae, and N. capsiformis, respectively.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 18 (1986), S. 5-22 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The characterization of single-mode fibres is important not only for determining the system parameters for a particular fibre, but also for the specification of fibres for manufacturing purposes. We present a detailed analysis of two new methods of characterizing single-mode fibres. The ‘strip integrated far-field method’ involves measuring the light power passed by a thin slit scanned across the far-field pattern and the ‘area integrated far-field method’ involves measuring the light power passed by a knife edge scanned across the far-field pattern. It is shown that, for either method, the measured data is related to the transverse offset transmission coefficient by the Fourier-cosine transform and hence that the far-field r.m.s. spot-size can be directly calculated. Noise analysis shows that the area integrated far-field method is superior to the strip integrated far-field method and similar to the ‘far-field mask method’ when a broadband light source is used to measure the far-field r.m.s. spot-size. It is also shown that the area integrated far-field method has smaller systematic errors than the far-field mask method.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 4714-4722 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Initial sticking probabilities for D2 dissociative chemisorption at a Ag(111) surface have been measured for translational energies in the range Ei=220–500 meV, as a function of incident angle θi and gas temperature, using seeded molecular beams. Sticking probabilities are dependent on the D2 internal state distribution and scale with the normal component of the translational energy. The data has been fit by assuming that dissociation is independent of molecular rotation, being the sum of contributions from molecules in different vibrational states v with a sticking function S0(Ei,θi,v)=A/2{1+tanh[Ei cos2 θi−E0(v)]/w(v)}, in a manner similar to the behavior on copper. Sticking parameters E0, the translational energy required for S0 to reach half of its maximum value, are determined with good precision (±25 meV) for levels v=3 (328 meV) and v=4 (170 meV) with width parameters w=54 and 63 meV, respectively, while the barriers for levels v=1 and 2 are close to the upper limit of the sticking data and E0 is estimated as 700±100 and 510±70 meV, respectively. Parameters for the vibrational ground state (v=0) could not be obtained, since sticking of this state is negligible at translational energies less than 500 meV. No dissociation could be observed at thermal energies Ei≤70 meV either on a flat or a defective surface. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-904X
    Keywords: lipoprotein distribution ; ultracentrifugation ; liposomes ; nystatin ; and cyclosporine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 3255-3264 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have explored the effect of alloying an unreactive metal, Sn, on the dynamics of D2 dissociative chemisorption at Pt(111). By comparing D2 sticking and recombinative desorption on Pt(111) with that on the ordered p(2×2) Sn/Pt(111) and ((square root of 3)×(square root of 3))R30° Sn/Pt(111) surface alloys, we examine the influence of the local surface composition on reactivity. The energy dependence of D2 sticking S(E) has been measured for all three surfaces using a hyperthermal beam. We find that the activation barrier for dissociative chemisorption is low on the p(2×2) alloy, but the sticking probability is reduced, compared to Pt(111), by an increase in the steric constraint on the dissociation site. Sticking on the ((square root of 3)×(square root of 3))R30° alloy is inefficient at thermal energies with a threshold of ∼280 meV, below which the sticking probability falls exponentially. The increase in the barrier to D2 dissociation occurs as the stable, high coordination Pt3–D binding sites are lost by formation of the ((square root of 3)×(square root of 3))R30° alloy. Despite the large activation barrier, sticking is dominated by the vibrational ground state with the barrier occurring in the entrance channel, before the D2 bond has stretched. Departures from a normal energy scaling indicate that the dissociation site is localized in the unit cell and we suggest favorable dissociation sites on the alloy surfaces. Estimates for the heats of adsorption, obtained by comparing activation energies to adsorption and desorption, indicate an abrupt decrease in the D binding energy as the Pt3 sites are lost. We show that sticking and desorption parameters are consistent with an increasing steric constraint for adsorption/desorption on the alloy surfaces as the Sn content is increased and an increase in the barrier to dissociation as the stable Pt3 sites are lost by alloying. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
  • 7
    Publication Date: 2018-03-28
    Description: Objectives There is growing evidence of an association between low-dose external -radiation and circulatory system diseases (CSDs), yet sparse data exist about an association with chronic internal uranium exposure and the role of non-radiation risk factors. We conducted a nested case–control study of French AREVA NC Pierrelatte nuclear workers employed between 1960 and 2005 to estimate CSD risks adjusting for major CSD risk factors (smoking, blood pressure, body mass index, total cholesterol and glycaemia) and external -radiation dose. Methods The study included 102 cases of death from CSD and 416 controls individually matched on age, gender, birth cohort and socio-professional status. Information on CSD risk factors was collected from occupational medical records. Organ-specific absorbed doses were estimated using biomonitoring data, taking into account exposure regime and uranium physicochemical properties. External -radiation was measured by individual dosimeter badges. Analysis was conducted with conditional logistic regression. Results Workers were exposed to very low radiation doses (mean -radiation dose 2 and lung uranium dose 1 mGy). A positive but imprecise association was observed (excess OR per mGy 0.2, 95% CI 0.004 to 0.5). Results obtained after adjustment suggest that uranium exposure might be an independent CSD risk factor. Conclusions Our results suggest that a positive association might exist between internal uranium exposure and CSD mortality, not confounded by CSD risk factors. Future work should focus on numerous uncertainties associated with internal uranium dose estimation and on understanding biological pathway of CSD after protracted low-dose internal radiation exposure.
    Keywords: Epidemiology
    Print ISSN: 1351-0711
    Electronic ISSN: 1470-7926
    Topics: Medicine
    Published by BMJ Publishing Group
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