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  • Articles  (47)
  • Springer  (47)
  • 1975-1979  (47)
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  • Articles  (47)
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  • 1
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Der Äquivalenzsatz von Lax über die Konvergenz der Lösung des diskretisierten Problems gegen die des gegebenen sachgemäß gestellten Anfangswertproblems zeigt, daß Stabilität notwendig und hinreichend für die Konvergenz ist, falls das Differenzenschema konsistent ist. In einer früheren Arbeit von Butzer-Weis wurde dieser Satz im Rahmen allgemeiner Banachräume mit Ordnungen versehen, im Sinne, daß Konsistenz, Stabilität und Konvergenz mit Ordnungen betrachtet werden. Nach geeigneter Abänderung der benutzten Definitionen besagt nun eine alternative Form des Äquivalenzsatzes von Lax, daß Konsistenz und Stabilität äquivalent zur Konvergenz sind. Dieses Ergebnis wird ebenfalls auf den Fall mit Ordnungen verallgemeinert. In der Tat sind beide Formen des Satzes von Lax gültig unter den gleichen Definitionen von Konsistenz, Stabilität und Konvergenz mit Ordnungen. Ein Beispiel zeigt, daß der letztere Satz in einem gewissen Sinne bestmöglich ist.
    Notes: Abstract The Lax equivalence theorem on the convergence of the solution of the discrete problem to that of the given properly posed initial-value problem states that if the difference scheme is consistent, then stability is necessary and sufficient for convergence. In a recent paper by Butzer-Weis this theorem was equipped with orders in the setting of arbitrary Banach spaces in the sense that consistency, stability and convergence were considered with orders. By modifying the concepts involved suitably, an alternative form of the Lax theorem reads that consistency and stability is equivalent to convergence. This result is also generalized to one containing orders, in fact, both forms of the Lax theorem are valid under the same definitions of consistency, stability, and convergence with orders. An example is given showing that the latter theorem is in a certain sense best possible.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta biotheoretica 28 (1979), S. 98-122 
    ISSN: 1572-8358
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A model for the trapping of animals with a circular pitfall is formulated. The model's assumptions are: (1) The animals move independently according to the same Brownian motions. (2) The boundary of the pitfall acts as an absorbing or elastic barrier. (3) Initially a fixed number of animals is independently homogeneously distributed over a finite study area (a), or the initial positions follow a homogeneous planar Poisson process (b). The model depends on three free parameters: (i) the motility of the animals, (ii) their reaction to the pitfall, (iii) the initial density. It appears that the catches in disjoint time intervals are multinomially (a) or independently Poisson (b) distributed. The parameters of these distributions are obtained by solving certain partial differential equations. Estimation and testing problems are considered, and the data of some laboratory and field experiments are analyzed. It appears that it is possible to estimate both the animals' motility and density from a pitfall experiment. However, the accuracy is very low. To solve this problem at least partially, experiments for the separate estimation of parameters other than the density are discussed.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 62 (1975), S. 236-237 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 63 (1976), S. 386-386 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    De economist 127 (1979), S. 599-599 
    ISSN: 1572-9982
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
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  • 6
    ISSN: 1432-0630
    Keywords: Magneto-optics ; Bi garnets ; Liquid phase epitaxy ; Crystal growth ; Radio active tracer analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Thulium iron garnet thin films substituted with bismuth and gallium were prepared by LPE from a PbO.B2O3 flux. Radioactive isotope tracers were added to the melt as the chemical analysis technique. The deviation from the ratio (Pb+Bi+Tm)/(Fe+Ga)=0.6 of the layers was large and a proportion of the thulium ions possibly lie on the octahedral crystallographic sites. The concentration of Bi, Pb, and Ga as a function of the growth temperature was studied. The magneto-optic properties show that the layers are well suited for use in a magneto-optic device. A figure of merit of 2.5 degree per decibel at λ=560 nm was obtained and some magnetic bubble parameters are also presented.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 32 (1976), S. 380-381 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During early embryogenesis ofTriturus vulgaris, RNA and nonhistone protein contents of neuroectoderm nuclei change with stage specifically. Maximum values were found in the late gastrula after embryonic induction, and in the late neurula with the formation of the neural tube. The stage-specific increases of RNA and nonhistone protein are correlated with a preceding increase of Feulgen-DNA content.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 48 (1976), S. 293-306 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson, the activity of various enzymes (transferase, lyases, oxidoreductases, hydrolases) have been studied in detail. The results of this enzyme-cytochemical study firmly demonstrate that the organ is metabolically highly active. The epithelial cells have a strong energy metabolism. Energy production can take place under aerobic as well as under anaerobic conditions. Evidence is presented that glucose from blood is directly utilized for energy demands. The epithelial cells show also high synthetic activities. The moderate amino acid metabolism may participate in the synthesis of an acid mucopolysaccharide-protein complex, especially in the so-called dark cells. Lipid metabolism appears to be restricted to the mitochondria, indicating a high turnover of lipid moieties in the membranes. In contrast to the normal looking mitochondria, the macromitochondria — besides shape and localization — have an extremely high lipid and monoamine metabolism, which may point to a special function in the cellular economy. The high activity of enzymes involved in the degradation of monoamines and in the hydration of CO2 is of particular physiological interest. The significance of the observations is discussed in relation to formerly obtained indications on the involvement of the saccus dorsalis in fluid secretion, extrusion of organic substances of low molecular weight into the ventricular system and uptake of organic substances from the cerebrospinal fluid. The hypothesis of the saccus dorsalis being an analogue of the choroid plexus is supported by several relevant data.
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  • 9
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During summer season and winter season of 1971 and 1972, the acoustic properties, defined as the acoustic climate, of 8 semi-natural plant communities in the Netherlands were investigated. It appeared that each plant community has its own acoustic climate as a consequence of the specific species composition and the specific acoustic properties of the soil. Seasonal changes influenced the acoustic climate to some extent, since during summer there is a better attenuation of low frequencies and in winter of mid frequencies. Comparing all plant communities the total variation in attenuation differed from 29.6 dB/100 m at 1250 Hz (cps) in winter to 74.6 dB/100 m at 10,000 Hz in summer, as is shown in Table 3. In general best attenuation occurred at low and high frequencies in both seasons, which has to be attributed to soil and foliage characteristics.
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  • 10
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Observations on predation by the diurnally active predator Notiophilus biguttatus F., show that locomotory activity of the prey favours capture. Of the two prey species studied, Orchesella cincta and Tomocerus minor, the former is by far the most active one during the day. Since the moulting rhythm causes only part of a group of O. cincta to be active, predation towards this species is selective: active specimens are “preferred”. Tomocerus minor is almost inactive during the day (but may be activated by disturbance from the predator), which inhibits such a selection. Orchesella cincta also shows, when attacked, a greater escape ability than T. minor. So, inactive O. cincta are captured less easily than T. minor. Thus, locomotory activity and escape ability both cause a variable preference of the predator. When a sufficiently high number of active O. cincta specimens is present, this species will be preferred; when the number of active O. cincta specimens is low, e.g. as a consequence of predation, T. minor might be preferred.
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