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Implications of weed composition and thrips species for the epidemiology of tomato spotted wilt in chrysanthemum (Dendranthema grandiflora) (1999)

Martinez, D. L. Ochoa ; Zavaleta-Mejía, E. ; Mora-Aguilera, G. ; [et al.]

Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd

Plant pathology 48 (1999), S. 0

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ISSN: 1365-3059

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The effects of 21 weeds acting as hosts of tomato spotted wilt virus (TSWV), temperature, thrips population and diversity on disease progress in chrysanthemum cv. Polaris were studied. Under greenhouse conditions, only Taraxacum officinale, Bidens sp., Resedaluteola and Mirabilis jalapa were hosts for TSWV. Of 38 weeds species in the area surrounding a chrysanthemum field, Tithonia tubaeformis and R. luteola had the highest populations of adult and immature thrips. These weeds, as well as M. jalapa, had an extensive seasonal distribution and may play a key role in the disease progress. Seventeen thrips species belonging to the genera Bravothrips, Thrips and Frankliniella were identified on weed flowers, with Frankliniella occidentalis (FOC) representing 9.5% of all thrips identified. Of 123 thrips collected from chrysanthemum inflorescences, 9.75% were FOC, and only 2.5% of them transmitted TSWV. Of all the thrips species collected from chrysanthemum flowers in the field, only FOC was capable of transmitting TSWV. On 120 experimental plots established at two sites, with three transplanting dates (June, July and August), it was estimated that 1.25% of the chrysanthemum cuttings were already infected with TSWV when transplanted. Secondary spread, vectored by FOC, occurred only for the earliest transplanting date and resulted in a further 2.36% disease incidence.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-3059.1999.00397.x

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White noise excited non-ideal elasto-plastic oscillator (1997)

Ditlevsen, O. ; Tarp-Johansen, N. J.

Springer

Acta mechanica 125 (1997), S. 31-48

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ISSN: 1619-6937

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: Summary Two sets of 50 samples of the displacement response of the top traverse relative to the second traverse of an experimental shear frame with three traverses subject to white noise base shaking of two different intensities have been recorded at Institut für Allgemeine Mechanik in 1995, and are in file available for analysis. The column connection between the two top traverses were made of aluminum with a linear-elastic non-ideal plastic behavior, and the columns were therefore renewed after each experiment. The two other connections were made of steel with a purely linear-elastic behavior. By use of the measured displacement-retaining force relation for the aluminum connection the plastic displacement responses were isolated from the sample records. From the obtained samples of plastic displacement records various distributions were estimated as well as the time development of the variance of the plastic displacement process. This paper presents a determination of the experimentally estimated statistical properties of the plastic response by use of Slepian model process theory as the basis for a numerical simulation algorithm. Solely the given defining parameters of the experimental frame are used in the calculations, i.e. the given displacement-retaining force relations, the traverse masses, the modal damping ratios for the vibrations within the elastic domain, and the two white noise excitation intensities, all as measured. First the Slepian model process method is applied to a single degree of freedom oscillator with linear-elastic non-ideal plastic displacement restoring force relation. The method is based on a direct generalization of the Slepian model process method that quite successfully has been developed for the linear-elastic ideal-plastic oscillator. Next the method is modified to be applicable on an oscillator of more than one degree of freedom. Applied to the experimental frame the calculations give excellent predictions of the main distributional properties of the plastic displacement process.