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  • 1995-1999  (3)
  • Unsealed roads  (1)
  • biochemical test  (1)
  • tick  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of engineering geology and the environment 57 (1999), S. 215-223 
    ISSN: 1435-9537
    Keywords: Key words Grading ; Particle size distribution ; Grading coefficient ; Unsealed roads
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Résumé L'importance de la granulométrie d'un matériau graveleux à utiliser sur des routes non-revêtues est connue depuis longtemps. Plusieurs paramètres ont eté developpés pour permettre l'interprétation des courbes granulométriques en fonction d'un seul paramètre pour faciliter les applications, contrôles et comparaisons. On montre qu'il existe des corrélations importantes entre beaucoup de paramètres bien connus, bien qu'il soit évident aussi que la dispersion des données indique qu'il se peut que ces paramètres sont indicatifs de propriétés qui diffèrent légèrement l'une de l'autre. L'étude a montré qu'un paramètre nouveau, le coefficient de granularité, est un bon indicateur de la granulométrie et qu'on peut l'utiliser de façon interchangeable avec beaucoup d'autres paramètres. En termes généraux, le coefficient de granularitééquivaut à peu près à la moitié du pourcentage du matériau graveleux dans un matériau donné, et les coefficients de granularité de 16 et 34 équivalent à peu près aux modules de granularité de 1.5 et 1.6 respectivement.
    Notes: Abstract  The importance of the particle size distribution (grading) of a gravel material for unsealed roads has long been recognized. Various parameters have been devised to allow interpretation of grading curves in terms of a single parameter for ease of application, control and comparison. It is shown that there are significant correlations between many of the better known parameters, although it is also clear from the scatter of the data that the parameters probably indicate slightly different properties. The investigation has shown that a new parameter, the grading coefficient, is a good indicator of the grading and can be used interchangeably with many other parameters. In general terms the grading coefficient is approximately half the percentage gravel in a material and grading coefficients of 16 and 34 are roughly equivalent to grading moduli of 1.5 and 2.6, respectively.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-9702
    Keywords: Boophilus microplus ; cattle tick ; pesticide resistance ; organophosphate ; biochemical test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rapid and sensitive detection of resistance to insecticides in arthropods is needed. In the cattle tick, Boophilus microplus, resistance to a variety of acaricides is widespread. The most commonly used assay for resistance, the larval packet test, takes at least two, but generally six weeks for a one-host tick like B. microplus to complete and may take up to three months to complete for three-host ticks. Here we describe a test for resistance to organophosphate acaricides that can be used on larvae and adult ticks which takes less than 24 hours. The test measures the difference in acetylcholinesterase (AChE) activity in homogenates of ticks in the presence and absence of propoxur, a carbamate acaricide. We found clear discrimination of organophosphate-susceptible and organophosphate-resistant adults with 100 μM propoxur. AChE from susceptible ticks had almost no activity at this concentration of propoxur whereas AChE from resistant ticks had 67% of its potential activity. AChE from heterozygote ticks could also be distinguished from AChE from homozygous-susceptible and homozygous-resistant ticks. This is the first biochemical test for resistance to an acaricide. Rapid, sensitive tests like ours will allow resistance to organophosphates to be detected soon after it develops in the field, thus, the spread of resistance might be slowed and the useful life of acaricides extended.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-9702
    Keywords: Boophilus microplus ; tick ; Ixodida ; resistance ; synthetic pyrethroid ; monooxygenases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We investigated the role of monooxygenases in resistance to synthetic pyrethroids (SPs) in the cattle tick, Boophilus microplus. We found that monooxygenases play only a minor role in resistance to SPs in both resistant and susceptible strains of B. microplus. We blocked the monooxygenases with piperonyl butoxide (PBO) and simultaneously applied the SPs, flumethrin and cypermethrin to larval B. microplus. PBO increased the effect of flumethrin (synergism ratios 2.7–8.9) more than it increased the effect of cypermethrin (synergism ratios 1.9–3.1). Of the four strains tested, Parkhurst, which is resistant to SPs, was the least affected by the addition of PBO (synergism ratios after cypermethrin was applied 1.9; after flumethrin 2.7) whereas N.R.F.S., the strain susceptible to SPs, was the most affected by synergism between PBO and SPs (synergism ratio after cypermethrin was applied 3.1; after flumethrin 8.9). We hypothesize that B. microplus lacks monooxygenases capable of conferring resistance to SPs because it and its recent ancestors were blood-feeders rather than herbivores.
    Type of Medium: Electronic Resource
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