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  • 11
    Electronic Resource
    Electronic Resource
    Toxin γ of the scorpionTityus serrulatus modifies both activation and inactivation of sodium permeability of nerve membrane (1986)
    Springer
    Pflügers Archiv 407 (1986), S. 92-99 
    Details
    ISSN: 1432-2013
    Keywords: Nerve membrane ; Na channel ; Activation ; Inactivation ; Scorpion toxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 1. The effects of the major neurotoxic fraction isolated from scorpion venom ofTityus serrulatus, TiTxγ, on peripheral nerve membrane ofXenopus laevis were studied under current- and voltage-clamp conditions. 2. 700 nmol/l TiTxγ depolarized the membrane and induced spontaneous activity (150s−1, maximum value), which ceased within a few minutes. It reduced the amplitude of the action potentials from 109 mV to 52 mV and increased their duration from 1.25 ms to 4.5 ms. 3. 440 nmol/l TiTxγ induced inward Na current flow at resting potential. The descending branch of the Na current-voltage curve was flattened and shifted approximately 10 mV to more negative potentials. Maximum Na permeability was reduced to about 20%. 4. Both development of and recovery from inactivation of Na permeability were slowed. The steepness of the steady-state inactivation curve was decreased, but the mid-potential changed only insignificantly. 5. No prepulse was necessary to elicit either a shift of activation or an inward current at resting potential. 6. Expressing the toxin effect either in terms of the decrease of Na peak current or of the slowing of inactivation, half-maximum effects were found with 0.3±0.1 and 3.7±0.7 μmol/l TiTxγ, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580727
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  • 12
    Electronic Resource
    Electronic Resource
    Meteorology: European collaboration on dynamic atmospheric fronts (1986)
    [s.l.] : Nature Publishing Group
    Nature 322 (1986), S. 114-115 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] METEOROLOGY is a science that depends on the collaborative links between those involved in developing basic theories and in data collection, analysis and forecasting. The European Mesoscale Frontal Dynamics Project, an intensive programme for observing and modelling active cold fronts passing over ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/322114a0
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  • 13
    Electronic Resource
    Electronic Resource
    A model for π-selfadjoint operators in π1 and a special linear pencil (1985)
    Springer
    Integral equations and operator theory 8 (1985), S. 13-35 
    Details
    ISSN: 1420-8989
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The eigenvalue of nonpositive type of a π-selfadjoint operator A in a Pontrjagin space of index one is characterized in a model of A. Similar questions are studied for an eigen-value problem λG-T in a Hilbert space with a selfadjoint operator T and a special operator G.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01199980
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  • 14
    Electronic Resource
    Electronic Resource
    On the application of the classic Kessler and Berry schemes in Large Eddy Simulation models with a particular emphasis on cloud autoconversion, the onset time of precipitation and droplet evaporation (1998)
    Springer
    Annales geophysicae 16 (1998), S. 628-637 
    Details
    ISSN: 0992-7689
    Keywords: Atmospheric composition and structure ; Cloud physics and chemistry ; Pollution ; Meteorology and atmospheric dynamics ; Precipitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Many Large Eddy Simulation (LES) models use the classic Kessler parameterisation either as it is or in a modified form to model the process of cloud water autoconversion into precipitation. The Kessler scheme, being linear, is particularly useful and is computationally straightforward to implement. However, a major limitation with this scheme lies in its inability to predict different autoconversion rates for maritime and continental clouds. In contrast, the Berry formulation overcomes this difficulty, although it is cubic. Due to their different forms, it is difficult to match the two solutions to each other. In this paper we single out the processes of cloud conversion and accretion operating in a deep model cloud and neglect the advection terms for simplicity. This facilitates exact analytical integration and we are able to derive new expressions for the time of onset of precipitation using both the Kessler and Berry formulations. We then discuss the conditions when the two schemes are equivalent. Finally, we also critically examine the process of droplet evaporation within the framework of the classic Kessler scheme. We improve the existing parameterisation with an accurate estimation of the diffusional mass transport of water vapour. We then demonstrate the overall robustness of our calculations by comparing our results with the experimental observations of Beard and Pruppacher, and find excellent agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-998-0628-2
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  • 15
    Electronic Resource
    Electronic Resource
    The influence of cloud structure and droplet concentration on the reflectance of shortwave radiation (1996)
    Springer
    Annales geophysicae 14 (1996), S. 845-852 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The effects of cloud shadowing, channelling, cloud side illumination and droplet concentration are investigated with regard to the reflection of shortwave solar radiation. Using simple geometric clouds, coupled with a Monte Carlo model the transmission properties of idealized cloud layers are found. The clouds are illuminated with direct solar radiation from above. The main conclusion reached is that the distribution of the cloud has a very large influence on the reflectivity of a cloud layer. In particular, if the cloud contains vertical gaps through the cloud layer in which the liquid water content is zero, then, smaller more numerous gaps are more influential on the radiation than fewer, larger gaps with equal cloud fraction. At very low solar zenith angles channelling of the radiation reduces the reflection expected on the basis of the percentage cloud cover. At high solar zenith angles the illumination of the cloud edges significantly increases the reflection despite the shadowing of one cloud by another when the width of the gaps is small. The impact of droplet concentration upon the reflection of cloud layers is also investigated. It is found that at low solar zenith angles where channelling is important, the lower concentrations increase the transmission. Conversely, when cloud edge illumination is dominant the cloud distribution is found to be more important for the higher concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-0845-5
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  • 16
    Electronic Resource
    Electronic Resource
    Pyramidal ice crystal scattering phase functions and concentric halos (1997)
    Springer
    Annales geophysicae 14 (1997), S. 1192-1197 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Phase functions have been calculated using the Monte Carlo/geometric ray tracing method for single hexagonal pyramidal ice crystals (such as solid and hollow bullets) randomly oriented in space and horizontal plane, in order to study the concentric halo formations. Results from three dimensional model calculations show that 9° halo can be as bright as the common 22° halo for pyramidal angle of 28°, and the 18°, 20°, 24° and 35° halos cannot be seen due to the strong 22° halo domination in the scattering phase function between 18° and 35°. For solid pyramidal ice crystals randomly oriented horizontally, the 35° arc can be produced and its intensity depends on the incident ray solar angle and the particle aspect ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-996-1192-2
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  • 17
    Electronic Resource
    Electronic Resource
    Wavelet analysis of turbulence in cirrus clouds (1997)
    Springer
    Annales geophysicae 15 (1997), S. 1447-1456 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Two flights of the UK Meteorological Office’s Hercules aircraft through daytime frontal cirrus around Scotland have been analysed using wavelet analysis on the vertical velocity time-series from the horizontal runs. It is shown that wavelet analysis is a useful tool for analysing the turbulence data in cirrus clouds. It finds the largest scales involved in producing turbulence, as does Fourier analysis, such as the 2-km spectral peaks corresponding to convective activity during flight A283. Wavelet spectra have the added advantage that the position is shown, and so they identify smaller-scale, highly localised processes such as the production of turbulent kinetic energy by the breaking of Kelvin-Helmholtz waves due to the vertical shear in the horizontal wind. These may be lost in Fourier spectra obtained for long time-series, though they contribute something to the average spectral density at the appropriate scale. The main disadvantage of this technique is that only octave frequency bands are resolved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-997-1447-6
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  • 18
    Electronic Resource
    Electronic Resource
    Preliminary laboratory studies of the optical scattering properties of the crystal clouds (1998)
    Springer
    Annales geophysicae 16 (1998), S. 618-627 
    Details
    ISSN: 0992-7689
    Keywords: Meteorology and atmosphere dynamics ; Climatology ; Radiative process ; Atmospheric composition and structure ; Cloud physics and chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Ice crystal clouds have an influence on the radiative budget of the earth; however, the exact size and nature of this influence has yet to be determined. A laboratory cloud chamber experiment has been set up to provide data on the optical scattering behaviour of ice crystals at a visible wavelength in order to gain information which can be used in climate models concerning the radiative characteristics of cirrus clouds. A PMS grey-scale probe is used to monitor simultaneously the cloud microphysical properties in order to correlate these closely with the observed radiative properties. Preliminary results show that ice crystals scatter considerably more at 90° than do water droplets, and that the halo effects are visible in a laboratorygenerated cloud when the ice crystal concentration is sufficiently small to prevent masking from multiple scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-998-0618-4
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  • 19
    Electronic Resource
    Electronic Resource
    Die Integralbeziehungen bei der stationären laminaren Strömung mit geschlossenen Stromlinien in annähernd kreisförmigen Gebieten (1960)
    Springer
    Czechoslovak journal of physics 10 (1960), S. 737-741 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Abstract Для стационарного ла минарного плоского т ечения с замкнутыми л иниями тока при большом числе Рей нольдса в областях бл изких круговым вывед ено два интегральных соотношения (5) и (9). Согла сно первому из них инт еграл силы трения вдо ль границы области течения прям о пропорционален дли не этой границы и вели чине вихра скорости в ядре течен ия. Из другого соотнош ения вытекает: объем ж идкости, протекающей за единицу времени че рез сечение рециркул яционного пограничн ого слоя, прямо пропорционале н интегралу вдоль гра ницы области от разно сти квадратов скорос ти течения на границе яд ра и скорости на грани це области и обратно п ропорционален величине вихра скоро сти в ядре и длине гран ицы области.
    Notes: Zusammenfassung Für die statioäre lineare ebene Strömung mit geschlossenen Stromlinien bei einer großen Reynoldsschen Zahl in annähernd kreisförmigen Gebieten werden zwei Integralbeziehungen (5) und (9) abgeleitet. Nach der ersten von diesen ist das Integral der Reibungskraft entlang der Grenze des Strömungsgebiets direkt proportional der Länge dieser Grenze und der Größe der Rotation der Geschwindigkeit im Kern der Strömung. Aus der zweiten Beziehung geht hervor: Das Volumen der in der Zeiteinheit den Schnitt der Rezirkulationsgrenzschicht durchfließenden Flüssigkeit ist direkt proportional dem Integral entlang der Gebietsgrenze aus der Differenz der Quadrate der Strömungsgeschwindigkeit an der Grenze des Kerns und der Geschwindigkeit an der Gebietsgrenze und umgekehrt proportional der Größe der Geschwindigkeitsrotation im Kern und der Länge der Gebietsgrenze.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01558103
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  • 20
    Electronic Resource
    Electronic Resource
    Winter Host Plant Specialization in a Host-Alternating Aphid (2000)
    Springer
    Journal of insect behavior 13 (2000), S. 815-825 
    Details
    ISSN: 1572-8889
    Keywords: aphids ; host alternation ; host plant specialization ; Rhopalosiphum padi ; Prunus spinosa ; Prunus padus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The host alternating aphid, Rhopalosiphum padi (L.), feeds in summer on several different species of grasses but is monophagous on its winter host, Prunus padus L. The monophagy on P. padus could be a result of the restricted host range of the several different generations colonizing, or feeding, on this host during autumn–winter–spring. This study shows that the winter host plant specificity of R. padi is controlled mainly by the preference of the females remigrating (gynoparae) to the winter host, P. padus, in autumn. The other generations living on the winter host, i.e., sexual females, males, and spring generations, all accept a broader range of winter hosts. One alternative host plant, Prunus spinosa L., could be utilized by all generations associated with the winter host, except for the females remigrating at autumn.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007806416332
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