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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 148 (1996), S. 583-589 
    ISSN: 1420-9136
    Keywords: Anisotropy ; dynamic ray tracing ; interfaces ; ray-centred coordinates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A 4×4-propagator matrix formalism is presented for anisotropic dynamic ray tracing, including the propagation across curved interfaces. The computations are organised in the same way as in Červený's well-known isotropic propagator matrix formalism. Attention is paid to cases where double eigenvalues of the Christoffel matrix result in unstable expressions in the dynamic ray tracing system, but where geometrical spreading is well-behaved.
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Phytopathology 25 (1987), S. 339-358 
    ISSN: 0066-4286
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Biology
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  • 3
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Phytopathology 36 (1998), S. 453-483 
    ISSN: 0066-4286
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Biology
    Notes: Abstract Nonpathogenic rhizobacteria can induce a systemic resistance in plants that is phenotypically similar to pathogen-induced systemic acquired resistance (SAR). Rhizobacteria-mediated induced systemic resistance (ISR) has been demonstrated against fungi, bacteria, and viruses in Arabidopsis, bean, carnation, cucumber, radish, tobacco, and tomato under conditions in which the inducing bacteria and the challenging pathogen remained spatially separated. Bacterial strains differ in their ability to induce resistance in different plant species, and plants show variation in the expression of ISR upon induction by specific bacterial strains. Bacterial determinants of ISR include lipopolysaccharides, siderophores, and salicylic acid (SA). Whereas some of the rhizobacteria induce resistance through the SA-dependent SAR pathway, others do not and require jasmonic acid and ethylene perception by the plant for ISR to develop. No consistent host plant alterations are associated with the induced state, but upon challenge inoculation, resistance responses are accelerated and enhanced. ISR is effective under field conditions and offers a natural mechanism for biological control of plant disease.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 102 (1990), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: If a sharp edge occurs in a reflector, the wavefield predicted by geometric ray theory shows shadow boundaries between illuminated zones and shadow zones. One may correct for these discontinuities in the wavefield by adding edge waves as introduced by Klem-Musatov. In this paper the edge wave is analysed as a solution of a parabolic differential equation that describes transverse diffusion between the illuminated zone and the shadow zone across the shadow boundary. Here, the edge wave is described constructively in terms of dynamic ray tracing, thereby indicating how it can be implemented in a ray tracing program when the latter is equipped with the facility of dynamic ray tracing.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5067-5072 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ti and TiN layers implanted with 57Fe ions were studied by conversion electron Mössbauer spectroscopy at 295 and 80 K. In as-implanted Ti samples the local states of iron implants were assigned to α-Ti(Fe) and β-Ti(Fe). In TiN, about 68% of iron implants replace Ti atoms forming Fe2N and nonstoichiometric Fe–N complexes. The remaining Fe ions replace N atoms exhibiting α-Ti(Fe) and β-Ti(Fe) states. The protective properties of the TiN cover layer are discussed in terms of changes of the these states after subsequent annealing in air. © 1995 American Institute of Physics.
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  • 6
    ISSN: 1573-8469
    Keywords: Tn5 transposon mutants ; root colonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting De invloed van een behandeling van aardappelpootgoed metPseudomonas putida isolaat WCS358 op de knolopbrengst werd onderzocht in verschillende gewasrotaties on een proefveld van proefboerderij ‘De Schreef’, Flevopolder. In de controlebehandelingen werd in een nauwe aardappelrotatie (1:3) een reductie van 11% in opbrengst van pootaardappelen (86 dagen na het poten) geconstateerd ten opzichte van een ruime aardappelrotatie (1:6); 130 dagen na het poten werd een vermindering met 14% gevonden in de opbrengst van consumptieaardappelen. Pootgoedbehandeling met het siderofoorproducerende isolaat WCS358 verhoogde de opbrengst van pootaardappelen in de 1:3-rotatie met 13%. Een Tn5-transposonmutant van dit isolaat die het vermogen sideroforen te produceren had verloren, had geen effect op de opbrengst. In de 1:6-rotatie had behandeling van pootgoed met WCS358 geen effect op de opbrengst van pootaardappelen. Zowel in de nauwe (1:3) als in de ruimte (1:6) rotatie werd (130 dagen na het poten), geen effect van behandeling van pootgoed met WCS358 op de opbrengst van consumptieaardappelen gevonden. Wortelkolonisatie door siderofoorproducerende Tn5-transposonmutanten van WCS358 nam aan het eind van het seizoen af. Er werd, 130 dagen na het poten, geen verschil in wortelkolonisatie geconstateerd tussen siderofoorproducerende en siderofoornegatieve Tn5-transposonmutanten. Siderofoorproduktie blijkt een voorwaarde te zijn voor verhoging van de knolopbrengst door WCS358 onder veldomstandigheden. De verhoging van de knolopbrengst treedt alleen op in de nauwe aardappelrotatie. Dit is de eerste keer dat de betrokkenheid van sideroforen bij groeistimulatie onder veldomstandigheden is aangetoond.
    Notes: Abstract The effect of treatment of potato seed tubers withPseudomonas putida isolate WCS358 on tuber yield was studied in different crop rotations at the Experimental Farm ‘De Schreef’, near Lelystad. With untreated, tuber yield in a 1:3 (short) rotation compared to yield in a 1:6 (long) rotation of potato was decreased by 11% at 86 days (seed tuber harvest) and by 14% at 130 days (ware potato harvest) after seeding. Seed tuber treatment with the wild-type isolate WCS358 increased tuber yield with 13% in a short rotation of potato 86 days after seeding, whereas a siderophore-negative Tn5 transposon mutant of this isolate had no effect on tuber yield. Seed tuber treatment with the wild-type isolate or the siderophore-negative mutant in a long rotation of potato had no effect on tuber yield. At 130 days after seeding no effect of any of the seed tuber treatments was found in both short and long rotations of potato. Root colonization by siderophore-producing Tn5 transposon mutants of WCS358 was decreased at the end of the growing season. No difference in root colonization between siderophore-producing and siderophore-negative Tn5 transposon mutants was found at 130 days after seeding. Siderophore production seems to be a prerequisite in potato tuber yield increase by WCS358 under field conditions. This is the first time that the involvement of siderophores in growth stimulation has been demonstrated in the field.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 13 (1992), S. 56-62 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A dual reference beam, plane wave, digital holographic interferometric system has been developed. It has also been applied as a non-intrusive optical diagnostic tool to a high speed flow. Quantitative density data has been extracted automatically by first generating phase-stepped interferograms. These were then digitized via a charge coupled device (CCD) camera and digitally post-processed within the memory of a computer. The results obtained have mapped an instantaneous 3-D density distribution of an unsteady flow field onto a 2-D projection plane. They show quantitatively the interaction between a shock wave and a turbulent boundary layer. A description has also been made showing how the dual reference beam technique can be extended to provide a quantitative density measurement of turbulent and unsteady flow structures.
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  • 8
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Synthetic aluminum-substituted maghemite samples, γ-(Al y Fe1-y )2O3 with y=0, 0.032, 0.058, 0.084, 0.106 and 0.151 have been studied by Mössbauer spectroscopy at 8 K and in the range 80 K to 475 K at steps of 25 K. The spectra have been analysed as a superposition of two sextets composed of asymmetrical Lorentzians. The A- and B-site isomer shifts were constrained as: δA=δB-0.12 mm/s. From the temperature dependence of δB it was possible to determine the characteristic Mössbauer temperature and the intrinsic shift. Both quantities clearly increase with increasing Al content, at least up to 10 mole%. The temperature dependence of the A-and B-sites hyperfine fields could be satisfactorily reproduced using the molecular-field theory assuming an antiparallel spin configuration. The exchange integrals were found as: J AB =-25 K; J AA =-18 K and J BB = -3 K. The hyperfine fields show a crossing in the vicinity of 300 K as a result of the relatively strong A-A interaction. The Curie temperature for the non-substituted sample was calculated to be 930 K and decreases to 765 K for the sample with 15 mol% Al. The gradual decrease of the saturation value of the A-site hyperfine field with increasing Al substitution and the constancy of this quantity for the B sites, suggest that the Al cations occupy the B sites.
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  • 9
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This report describes the results of the comparison of three different methods and three monoclonal antibodies to stain cells in suspension for incorporated bromodeoxyuridine and total DNA content. The procedures were tested in three different experimental tumour cell lines. The sensitivity of the different procedures was expressed as the ratio of the anti-BrdUrd fluorescence intensities of the S and G1 phase cells (FS/FG1 ratio). There were remarkable differences in sensitivity between the different procedures. With the heat denaturation the most favourable FS/FG1 ratio's were obtained but substantial cell loss occurred during this procedure which is a disadvantage for clinical application. With the pepsin digestion + acid denaturation procedure cell loss was negligible. The standard acid denaturation procedure was inferior to the other two methods. Using the pepsin digestion + acid denaturation procedure we examined the variations in sensitivity for the different monoclonal antibodies and cell lines and the influence of BrdUrd concentration, labelingtime and cell concentration. The binding characteristics for the various antibodies differed considerably in our hands. Only with the IU4 antibody we obtained FS/FG1 ratio's comparable with those desenbed in the literature. No difference was observed between the cell lines. Variation in cell concentration between 1 × 104 to 1 × 106 ml nor BrdUrd concentration appeared to influence the sensitivity of the procedure. A labelingtime of 1 h or even 30 min seems to be more than sufficient for an optimal FS/FG1 ratio. Our results indicate that using the appropriate antibody and immunofluorescence BrdUrd can be detected by flow cytometry, after incorporation into the DNA of tumour cells under a wide range of culture conditions. For clinical application, the pepsin digestion + acid dena uration method in combination with IU4 antibody seems to be the procedure of choice due to its good reproducibility, sensitivity and its low cell loss.
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  • 10
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The lepidocrocite (γ-FeOOH) to maghemite (γ-Fe2O3), and the maghemite to hematite (α-Fe2O3) transition temperatures have been monitored by TGA and DSC measurements for four initial γ-FeOOH samples with different particle sizes. The transition temperature of γ-FeOOH to γ-Fe2O3 and the size of the resulting particles were not affected by the particle size of the parent lepidocrocite. In contrast, the γ-Fe2O3 to γ-Fe2O3 transition temperature seems to depend on the amount of excess water molecules present in the parent lepidocrocite. Thirteen products obtained by heating for one hour at selected temperatures, were considered. Powder X-ray diffraction was used to qualify their composition and to determine their mean crystallite diameters. Transmission electron micrographs revealed the particle morphology. The Mössbauer spectra at 80 K and room temperature of the mixed and pure decomposition products generally had to be analyzed with a distribution of hyperfine fields and, where appropriate, with an additional quadrupole-splitting distribution. The Mössbauer spectra at variable temperature between 4.2 and 400 K of two single-phase γ-Fe2O3 samples with extremely small particles show the effect of superparamagnetism over a very broad temperature range. Only at the lowest temperatures (T⩽55 K), two distributed components were resolved from the magnetically split spectra. In the external-field spectra the ΔmI=0 transitions have not vanished. This effect is an intrinsic property of the maghemite particles, indicating a strong spin canting with respect to the applied-field direction. The spectra are successfully reproduced using a bidimensional-distribution approach in which both the canting angle and the magnetic hyperfine field vary within certain intervals. The observed distributions are ascribed to the defect structure of the maghemites (unordered vacancy distribution on B-sites, large surface-to-bulk ratio, presence of OH- groups). An important new finding is the correlation between the magnitude of the hyperfine field and the average canting angle for A-site ferric ions, whereas the B-site spins show a more uniform canting. The Mössbauer parameters of the two hematite samples with MCD104 values of respectively 61.0 and 26.5 nm display a temperature variation which is very similar to that of small-particle hematites obtained from thermal decomposition of goethite. However, for a given MCD the Morin transition temperature for the latter samples is about 30 K lower. This has tentatively been ascribed to the different mechanisms of formation, presumably resulting in slightly larger lattice parameters for the hematite particles formed from goethite, thus shifting the Morin transition to lower temperatures.
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