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  • 1
    Call number: MOP Per 843/B(65)
    In: Technische rapporten
    Type of Medium: Monograph available for loan
    Pages: 5 S.
    Series Statement: Technische rapporten 65
    Location: MOP - must be ordered
    Branch Library: GFZ Library
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  • 2
    Publication Date: 2005
    Keywords: Stress ; Physical properties of rocks ; Modelling ; Review article ; density ; elastic ; constants ; Gravimetry, Gravitation ; Seismics (controlled source seismology) ; Inversion
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  • 3
    ISSN: 1573-9708
    Keywords: field surveys ; GPR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Characterization of the shallow subsurface (0.25 to 10 m) is of growing importance for engineering activities, solutions of environmental problems, and archaeological investigations. Ground-penetrating radar (GPR) is an appropriate technique considering the depth range of interest, the strength of electric and magnetic contrasts between different subsurface layers and buried objects, and the required resolution. GPR surveys can detect subsurface structures by recording electromagnetic reflections from discontinuities. The detectability of objects and the delineation of subsurface structures increases with increasing wave velocity and conductivity differences between the object and its surroundings or between adjacent layers. However, unwanted reflections from objects above the surface influence the images. Shielded antennas can be used to avoid strong reflections from these objects. The data thus obtained are, however, more difficult to interpret. The fundamentals of GPR and two different acquisition setups for a GPR system are discussed. Basic interpretation tools for travel-time and velocity estimation are described, and finally, case studies are presented, followed by conclusions.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1570-7458
    Keywords: prey traces ; predator hunger ; search activity ; predation ; Carabidae ; Collembola
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Cet article décrit l'influence de trois paramètres liés à la densité des proies sur le comportement locomoteur de N. biguttatus. Les trois paramètres testés expérimentalement ont été: les traces laissées dans l'habitat par une proie invisible, le contenu de l'estomac, et la ration alimentaire quotidienne du carabe. Les résultats indiquent que le conditionnement de l'habitat par les traces augmente le nombre de périodes d'activité, mais diminue en même temps leur durée, si bien que la durée totale reste constante. La réplétion de l'estomac réduit l'effet des traces (ou conditionnement) de l'habitat. L'analyse de la probabilité maximale a montré que le modèle éthologique peut être décrit au mieux comme un mélange de deux types d'activités, l'une d'entre elles correspondant vraisemblablement au comportement de prospection. Il est ainsi possible de quantifier les résultats expérimentaux en termes de fréquence du comportement de prospection.
    Notes: Abstract The locomotory behaviour of the predatory beetle Notiophilus biguttatus F. was examined as a function of three experimental factors: prey traces left in the environment, gut contents and daily food ration. Prey traces led to an increase in the frequency of runs and stops. The size of this effect depended on gut contents. Maximum-likelihood analysis showed that the activity pattern could be described as a mixture of two kinds of activity, one of them presumably reflecting search behaviour. This enabled a quantification of the experimental results in terms of the frequency with which the beetle exibited search behaviour.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1536
    Keywords: Dispersion polymerization in non-aqueous media ; polymethylmethacrylate latex ; poly(12-hydroxy stearic acid)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The dispersion polymerization of methylmethacrylate stabilized by poly(12-hydroxy-stearic acid) in hydrocarbon media has been investigated. Unlike earlier results [7] it was found that stable latex particles can be prepared in the initial monomer concentration range 8.5 % to 34 %. To obtain stable particles varying amounts of stabilizer were used.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1539-6924
    Keywords: RfD ; uncertainty distributions ; extrapolation factors ; benchmark dose ; critical effect size ; critical effect dose ; human health risks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The use of uncertainty factors in the standard method for deriving acceptable intake or exposure limits for humans, such as the Reference Dose (RfD), may be viewed as a conservative method of taking various uncertainties into account. As an obvious alternative, the use of uncertainty distributions instead of uncertainty factors is gaining attention. This paper presents a comprehensive discussion of a general framework that quantifies both the uncertainties in the no-adverse-effect level in the animal (using a benchmark-like approach) and the uncertainties in the various extrapolation steps involved (using uncertainty distributions). This approach results in an uncertainty distribution for the no-adverse-effect level in the sensitive human subpopulation, reflecting the overall scientific uncertainty associated with that level. A lower percentile of this distribution may be regarded as an acceptable exposure limit (e.g., RfD) that takes account of the various uncertainties in a nonconservative fashion. The same methodology may also be used as a tool to derive a distribution for possible human health effects at a given exposure level. We argue that in a probabilistic approach the uncertainty in the estimated no-adverse-effect-level in the animal should be explicitly taken into account. Not only is this source of uncertainty too large to be ignored, it also has repercussions for the quantification of the other uncertainty distributions.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-9923
    Keywords: binomial fractions ; microbial counts ; variability ; uncertainty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In microbiological studies various methods are employed to estimate fractions from paired counts of organisms. When the fraction (second count divided by first count) is constant among the paired counts, the maximum likelihood estimate is the ratio of the arithmetic means. In many practical applications this fraction may however not be constant, but vary substantially between pairs of counts. We discuss a statistical method that estimates the distribution of the fraction from pairs of counts, to allow for this variation. Four real data sets (concerning viability for growth and infection, recovery of a detection method, and removal in a treatment process) are analyzed by this method. Often, pairs of counts are not determined in the same physical sample, but the first count is made in one sample, and the second count in a second sample. We provide parametric models to deal with such a situation: the desired fraction is still estimated as a binomial probability, but the model includes sampling effects. This approach also allows for analysis of two distinct cases: paired observations, where the counts “before” and “after” are related in some way to each other, and unpaired observations, where they are not. The four models for separate samples: paired or unpaired observations, and binomial probability fixed or variable, are used to analyze the removal data. It is concluded that this approach of statistical analysis of fractions is more appropriate than often used calculations based on the ratio between the (geometric) means “before” and “after”. The implications for risk analysis are briefly discussed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using a deep submicron structuring process for oxide superconducting films, we have fabricated planar YBa2Cu3O7−δ-Ag-YBa2Cu3O7–δ proximity junctions operating in the liquid nitrogen temperature region. Under microwave radiation Shapiro steps are generated in the current-voltage characteristic, in accordance with the resistively shunted junction model.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Zusammenfassung Messungen der Konzentration von Aitken-Kernen mit einem photoelektrischen Zähler auf dem Jungfraujoch ergeben ein Maximum bei meist neutraler Stabilität der Luft in der Schicht bis 3500 m. Parallelmessungen mit einer thermischen Diffusionskammer und einem Aitken-Kern-Zähler zeigen, daß bei Schönwetterlagen ein hoher Prozentanteil von Aitken-Kernen (im Mittel 69%) auch als Wolkenkerne (Übersättigung 〈1%) wirksam ist. Bei Schneefall ist dagegen der Prozentanteil von Aitken-Kernen, die auf diese Art wirksam sind, nur normal oder sehr klein (im Mittel 20%). Messungen der Gefrierkerne im Schnee ergeben im allgemeinen eine Zunahme der Anzahl aktiver Gefrierkerne nach einer Exponentialfunktion bei abnehmender Temperatur. Bei einigen Beobachtungen fiel eine hohe Gefrierkernkonzentration im Schnee mit kleinen Aitken-Kern-Konzentrationen zusammen. Auch bei relativ hohen Temperaturen waren die Wolken auf dem Jungfraujoch vollständig vereist, wahrscheinlich, weil Eiskristalle von den Schneefeldern aufgeweht werden.
    Notes: Summary Aitken nucleus concentration measurements with a photo-electric counter at the Jungfraujoch show a maximum at almost neutral stability of the air in the layer up to ≈3500 m. Simultaneous measurements with a thermal diffusion chamber and an Aitken nucleus counter show that in fine weather situations a high percentage of the Aitken nuclei (average 69%) is also active as cloud nuclei (supersaturation 〈1%). In snowfall situations, however, the percentage of Aitken nuclei that can act in this way is normal or very low (average 20%). Ice nucleus measurements in snow normally show an exponential increase of the number of active ice nuclei with decreasing temperature. In some observations a high ice nucleus concentration in the snow coincides with low Aitken nucleus concentrations. Even at rather high temperatures the clouds at the Joch were completely glaciated, probably because of ice crystals blown up from the snow-fields.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1539-6924
    Keywords: Cancer model ; cell proliferation ; two-stage model ; approximate solution ; MVK model ; hazard rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The approximate solution of the two-stage clonal expansion model of cancer may substantially deviate from the exact solution, and may therefore lead to erroneous conclusions in particular applications. However, for time-varying parameters the exact solution (method of characteristics) is not easy to implement, hampering the accessibility of the model to nonmathematicians. Based on intuitive reasoning, Clewell et al. (1995) proposed an improved approximate solution that is easy to implement whatever time-varying behavior the parameters may have. Here we provide the mathematical foundation for the approximation suggested by Clewell et al. (1995) and show that, after a slight modification, it is in fact an exact solution for the case of time-constant parameters. We were not able to prove that it is an exact solution for time-varying parameters as well. However, several computer simulations showed that the numerical results do not differ from the exact solution as proposed by Moolgavkar and Luebeck (1990). The advantage of this alternative solution is that the hazard rate of the first malignant cell can be evaluated by numerically integrating a single differential equation.
    Type of Medium: Electronic Resource
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