Analysis and dissipation of the antiparasitic agent ivermectin in cattle dung under different field conditions.

Cattle treated with the veterinary parasiticide ivermectin fecally excrete residues. The authors report the exposition and dissipation characteristics of these residues in dung of ivermectin-treated cattle and in soil beneath this dung on pastures in Canada, France, Switzerland, and The Netherlands. Residues were quantified for dung collected from cattle after 3 d, 7 d, 14 d, and 28 d posttreatment and subsequently exposed in the field for up to 13 mo.

A four-country ring test of nontarget effects of ivermectin residues on the function of coprophilous communities of arthropods in breaking down livestock dung.

By degrading the dung of livestock that graze on pastures, coprophilous arthropods accelerate the cycling of nutrients to maintain pasture quality. Many veterinary medicinal products, such as ivermectin, are excreted unchanged in the dung of treated livestock. These residues can be insecticidal and may reduce the function (i.

Validation of a standard field test method in four countries to assess the toxicity of residues in dung of cattle treated with veterinary medical products.

Registration of veterinary medical products includes the provision that field tests may be required to assess potential nontarget effects associated with the excretion of product residues in dung of treated livestock (phase II, tier B testing). However, regulatory agencies provide no guidance on the format of these tests. In the present study, the authors report on the development of a standardized field test method designed to serve as a tier B test.

Field hydration state varies among tropical frog species with different habitat use.

We have previously shown that ecological habit (e.g., arboreal, terrestrial, amphibious) correlates with thermoregulatory behaviors and water balance physiology among species of hylid frogs in northern Australia.

Critical viscoelastic behavior of polydimethylsiloxane networks around the sol-gel threshold.

Seven model polydimethylsiloxane (PDMS) networks were obtained by hydrosilation of a difunctional vinyl-terminated PDMS prepolymer with a SiH-containing cross-linker. Viscoelastic experiments, completed by size exclusion chromatography and static light scattering experiments, were performed in order to study the influence of molecular parameters on the dynamic properties around the sol-gel threshold. The dynamic critical parameter u was determined from experiments close to and above the sol-gel threshold.